Patent Description:
For centrifugal compressors, they are often used in large refrigerating units and typically use bearings that do not require lubrication oil (oil-free bearings). When high-speed small centrifugal compressors are desired, the cost of high-speed oil-free bearings is too high. It is therefore desirable to provide bearings that require the use of lubrication oil and to design simplified lubrication oil passages. On the other hand, it is desirable to simplify the structure of the centrifugal compressor, so that a compact and small centrifugal compressor can be provided.

<CIT>, <CIT>, <CIT>, and <CIT> each disclose a centrifugal compressor driven by a motor, wherein the pressurized fluid outputted by the centrifugal compressor is used to cool the motor.

An object of the present invention is to solve or at least alleviate the problems existing in the related art.

In an aspect, a centrifugal compressor, especially a centrifugal compressor adapted to be vertically arranged, is provided, which includes:.

Optionally, the guide member is partially located outside the shell.

Optionally, the rotor shaft is supported by a first bearing at a lower part and a second bearing at an upper part, a bottom part of the shell has an oil tank, and the lower end of the rotor shaft is located in the oil tank; the rotor shaft defines an axial or oblique oil passage therein, and has radial perforations at positions corresponding to the first bearing and the second bearing.

Optionally, the bottom of the motor housing is connected to the shell through a support bracket, the top of the motor housing is connected to the second bearing bracket, and the second bearing bracket is supported by the shell; the oil cup includes an oil guide pipe that is arranged obliquely to guide oil in the oil cup to an inner wall of the shell so that the oil is returned to the oil tank.

Optionally, the centrifugal compression mechanism includes one or more compression stages.

Optionally, the centrifugal compression mechanism includes a first-stage impeller, a partition, a volute, and a second-stage impeller, wherein an outlet of the volute communicates with the fluid outlet of the shell, the fluid passes between an upper surface of the volute and the partition after being compressed by the first-stage impeller, is then compressed by the second-stage impeller, and then exits via the output port of the volute.

In another aspect, a refrigerating device is provided, which includes the centrifugal compressor according to various embodiments.

The contents of the present invention will become easier to understand with reference to the accompanying drawings. It can be easily understood by those skilled in the art that the drawings are merely used for illustration, and are not intended to limit the scope of protection of the present invention. In addition, like parts are denoted by like numerals in the drawings, wherein:.

The scope of protection of the present invention is solely defined by the appended claims. Therefore, the following specific embodiments and the accompanying drawings are merely exemplary illustrations of the technical solutions of the present invention, and should not be regarded as the entirety of the present invention or as definitions or limitations to the technical solutions of the present invention.

The orientational terms that have been mentioned or might be mentioned in this specification, such as "upper", "lower", "left", "right", "front", "rear", "front side", "back side", "top", "bottom", etc., are defined relative to the configurations shown in the drawings. They are relative concepts, so they may change accordingly according to their different locations and different states of use. Therefore, these or other orientational terms should not be interpreted as restrictive terms.

Referring to <FIG> and <FIG>, a centrifugal compressor is shown, which includes: a shell <NUM>, which has a fluid inlet <NUM> and a fluid outlet <NUM>, the fluid inlet <NUM> being located at a top of the shell; a motor assembly <NUM>, which is arranged in the shell <NUM> and includes a stator <NUM> and a rotor, wherein the rotor includes a rotor shaft <NUM>, and the rotor shaft <NUM> includes a lower end <NUM> and an upper end <NUM>; a centrifugal compression mechanism <NUM>, impellers <NUM>, <NUM> of which are connected with the rotor shaft <NUM> (such as its upper end <NUM>) so as to be driven by the motor assembly <NUM>, wherein the centrifugal compression mechanism is arranged downstream of the fluid inlet <NUM> (such as directly below the fluid inlet <NUM>) to receive fluid, compress and pressurize the fluid, and output the pressurized fluid in a direction away from the motor assembly <NUM>; and a guide member <NUM>, which receives the pressurized fluid from the centrifugal compression mechanism <NUM>, and which defines a flow passage alone or together with a part of the shell, wherein the flow passage is configured such that the pressurized fluid from the centrifugal compression mechanism <NUM> passes through the motor assembly <NUM> and is discharged from the fluid outlet <NUM>, substantially as indicated by the hollow arrows.

In the centrifugal compressor according to the embodiment of the present invention, after entering the shell through a suction chamber, the fluid can immediately enter the centrifugal compression mechanism <NUM>, and is compressed and pressurized by the centrifugal compression mechanism <NUM>. For example, after a two-stage compression and pressurization, the fluid is then guided and diverted by the guide member <NUM> to return to the shell <NUM>, thereby cooling the motor assembly <NUM>, including passing through a gap G2 between the rotor and the stator and an outer side of a motor housing <NUM>; then, the fluid is discharged from the fluid outlet <NUM>. A feature of the centrifugal compressor according to the embodiments of the present invention is that the compressed gas is guided to pass through the motor assembly, thereby cooling the motor assembly. Since the fluid according to the embodiment of the present invention passes through the centrifugal compression mechanism <NUM> from top to bottom, when the centrifugal compression mechanism <NUM> is working, the impellers thereof will exert an upward force on the rotor shaft <NUM>, which counteracts the gravity of the rotor shaft <NUM> itself, thereby reducing axial stress of bearings <NUM> and <NUM> that support the rotor shaft <NUM>. In addition, the device according to this embodiment provides a centrifugal compressor with a compact design so as to be applied to low-power operating conditions.

The guide member <NUM> is formed as a pipe, for example as shown in <FIG>. In the embodiment shown in <FIG>, the guide member <NUM> is partially located outside the shell <NUM>; in other words, it has a part extending outside the shell <NUM>. The guide member <NUM> has a first end <NUM> connected to an output port <NUM> of the centrifugal compression mechanism, a second end <NUM> connected to a side wall of the shell, such as a lower part of the side wall of the shell <NUM>, and a pipe body <NUM> connected between the first end <NUM> and the second end <NUM> and including curved parts <NUM> and <NUM>. In some embodiments, the guide member <NUM> diverts the fluid flowing out of the centrifugal compression mechanism <NUM> by about <NUM> degrees for example, such as <NUM> degrees to <NUM> degrees. For example, from a direction substantially away from the motor assembly <NUM>, the fluid is diverted into a direction approaching the motor assembly <NUM>, and then returns to the interior of the shell <NUM> and cools the motor assembly <NUM>. As shown in <FIG>, the second end <NUM> of the guide member <NUM> extends into the shell <NUM> and is aligned with an opening <NUM> at the bottom of the motor housing <NUM>. There is a gap G1 between the second end <NUM> and the opening <NUM>, so that the airflow from the guide member <NUM> partially passes through the gap G2 between the motor stator and the rotor, and partially passes through the space between the motor assembly and the shell <NUM>. The top of the motor housing <NUM> may also have an opening <NUM> to allow the airflow that have passed through the gap G2 to exit, and an oil guide pipe <NUM> may extend out of the opening <NUM>. In some embodiments, the fluid outlet <NUM> of the shell <NUM> may be aligned with or adjacent to the opening <NUM> so that the airflow can be easily discharged. In some embodiments, the fluid outlet <NUM> may be arranged at other positions, for example, a position higher than a connection <NUM> between the second end <NUM> of the guide member <NUM> and the shell <NUM>, such as being flush with the opening <NUM> at a higher position of the motor housing <NUM>.

In the illustrated embodiment, the rotor shaft <NUM> is supported by a first bearing <NUM> at a lower part and a second bearing <NUM> at an upper part. The first bearing <NUM> is disposed in a first bearing seat <NUM> at the bottom of the motor assembly <NUM>, and the second bearing <NUM> is disposed in a second bearing bracket <NUM> at the top of the motor assembly. The shell <NUM> substantially includes a bottom part <NUM>, a middle part <NUM> and a top part <NUM>, and may have an overall substantially cylindrical shape. The fluid inlet <NUM> may be formed as a pipe, which may extend in an axial direction or vertical direction, and may be aligned with an inlet of the centrifugal compression mechanism <NUM>. The bottom part <NUM> of the shell <NUM> has an oil tank. Oil for the first bearing <NUM>, the second bearing <NUM> and other optional members may be contained in the oil tank. The lower end <NUM> of the rotor shaft <NUM> may be located in the oil tank; specifically, it may be inserted into a limiting member <NUM> in the oil tank. The rotor shaft <NUM> defines an axial or slightly oblique oil passage <NUM> therein. For example, as shown, the rotor shaft may be formed as a hollow member with an oil passage <NUM> therein. The oil passage <NUM> may be straight (in the axial direction of the rotor shaft <NUM>) or oblique. The rotor shaft <NUM> has radial perforations <NUM> and <NUM> at positions corresponding to the first bearing <NUM> and the second bearing <NUM>, respectively. When the centrifugal compressor is working, the rotation of the rotor shaft <NUM> will generate negative pressure in the oil passage <NUM>, so that the oil in the oil tank is drawn through the oil passage <NUM> in the direction of the arrows, and the oil will flow radially out of the perforations <NUM>, <NUM> under centrifugal force, thereby lubricating the first bearing <NUM> and the second bearing <NUM>. The oil that has passed through and lubricated the first bearing <NUM> directly returns to the oil tank under gravity. An oil cup <NUM> is arranged below the second bearing <NUM>. The oil that has passed through and lubricated the second bearing <NUM> falls into the oil cup <NUM>, is guided to an inner side of a side wall of the shell through the obliquely arranged oil guide pipe <NUM>, and returns to the oil tank along the inner side of the side wall of the shell. The arrangement of the oil cup <NUM> and the oil guide pipe <NUM> prevents the lubrication oil from entering the interior of the motor assembly. In some embodiments, a diameter of the perforation <NUM> corresponding to the first bearing <NUM> may be smaller than a diameter of the perforation <NUM> corresponding to the second bearing <NUM> to prevent the oil from flowing out of the perforation <NUM> too much to reach the perforation <NUM>.

With reference to <FIG> and <FIG>, in the illustrated embodiment, in the motor assembly: the stator <NUM> may be fixed on an inner side of the motor housing <NUM>; and the rotor may be located radially inwardly of the stator. In some embodiments, the rotor may include a permanent magnet <NUM>, and the stator <NUM> may have a winding. When the stator <NUM> is energized, the rotor is capable of rotating relative to the stator <NUM>. The motor assembly may further include: a first bearing seat <NUM> at a bottom of the motor housing <NUM> and a first bearing <NUM> therein; an oil cup <NUM> at a top of the motor housing <NUM>; and a second bearing bracket <NUM> located above the oil cup <NUM> and a second bearing <NUM> therein. In an alternative embodiment, the motor assembly may have other suitable structures and components. In the illustrated embodiment, the bottom of the motor housing <NUM> is connected to the shell <NUM> through several support brackets <NUM>. For example, the bottom is connected to the inner side of the side wall of the shell <NUM>. The top of the motor housing <NUM> is connected to the second bearing bracket <NUM>, and the second bearing bracket <NUM> is mounted on the shell <NUM>, such as being directly supported on the middle part <NUM> of the shell <NUM> or connected to the inner wall of the shell <NUM>.

The centrifugal compression mechanism <NUM> is arranged on the second bearing bracket <NUM>. For example, in some embodiments, a volute <NUM> of the centrifugal compression mechanism may be directly arranged on the second bearing bracket <NUM>. Although shown in the drawings, the centrifugal compression mechanism <NUM> includes two stages consisting of a first-stage impeller <NUM> and a second-stage impeller <NUM>. In an alternative embodiment, the centrifugal compression mechanism <NUM> may only include one stage or more than two stages. In the illustrated embodiment, the centrifugal compression mechanism <NUM> includes the first-stage impeller <NUM>, a partition <NUM>, the volute <NUM>, and the second-stage impeller <NUM>, through which the rotor shaft <NUM> passes. The first-stage impeller <NUM> and the second-stage impeller <NUM> are connected to the rotor shaft <NUM> and rotate with the rotor shaft, whereas the partition <NUM> and the volute <NUM> are relatively fixed. A first sleeve <NUM> is arranged between the first-stage impeller <NUM> and the second-stage impeller <NUM>, and a second sleeve <NUM> is arranged between the second-stage impeller <NUM> and the second bearing <NUM>. In the illustrated embodiment, the output port <NUM> of the volute <NUM> is in communication with the first end <NUM> of the guide member <NUM>. The fluid entering the centrifugal compression mechanism <NUM> through the fluid inlet <NUM> is compressed by the first-stage impeller <NUM> and then passes between an upper surface of the volute <NUM> and the partition <NUM>. Then, the fluid is compressed by the second-stage impeller <NUM>, exits from the output port <NUM> of the volute, and enters the flow passage defined by the guide member <NUM>. In an alternative embodiment, the volute <NUM> may include a second fluid inlet for connection with an economizer.

Claim 1:
A centrifugal compressor, comprising:
a shell (<NUM>), which has a fluid inlet (<NUM>) and a fluid outlet (<NUM>), the fluid inlet (<NUM>) being located at a top of the shell (<NUM>);
a motor assembly (<NUM>), which is arranged in the shell (<NUM>) and comprises a stator (<NUM>) and a rotor, the rotor comprising a vertically arranged rotor shaft (<NUM>), and the rotor shaft (<NUM>) comprising a lower end (<NUM>) and an upper end (<NUM>);
a centrifugal compression mechanism (<NUM>), an impeller (<NUM>, <NUM>) of which is connected with the rotor shaft (<NUM>) so as to be driven by the motor assembly (<NUM>), wherein the centrifugal compression mechanism (<NUM>) is arranged downstream of the fluid inlet (<NUM>) to receive a fluid, compress and pressurize the fluid, and output the pressurized fluid in a direction away from the motor assembly (<NUM>); and
a guide member (<NUM>), which receives the pressurized fluid from the centrifugal compression mechanism (<NUM>), and which defines a flow passage alone or together with a part of the shell (<NUM>), wherein the flow passage is configured such that all of the pressurized fluid from the centrifugal compression mechanism (<NUM>) passes through and cools the motor assembly (<NUM>) and is discharged from the fluid outlet (<NUM>);
wherein the guide member (<NUM>) is a pipe and wherein the guide member (<NUM>) has a first end (<NUM>) connected to an output port (<NUM>) of the centrifugal compression mechanism (<NUM>), a second end (<NUM>) connected to a side wall of the shell (<NUM>), such as a lower part of the side wall of the shell (<NUM>), and a pipe body (<NUM>) connected between the first end (<NUM>) and the second end (<NUM>) and comprising a curved part (<NUM>, <NUM>);
characterised in that:
the second end (<NUM>) extends into the shell (<NUM>) and is aligned with an opening (<NUM>) at a bottom of a motor housing (<NUM>) of the motor assembly (<NUM>) such that a gap (G1) is defined between the second end (<NUM>) and the opening (<NUM>);
a first portion of the pressurized fluid passes from the second end into the opening and through a first pathway (G2) within the motor housing (<NUM>); and
a second portion of the pressurized fluid passes from the second end through the gap and through a second pathway (G1) between the motor housing (<NUM>) and the shell (<NUM>).