Patent Description:
Some compressors provide cooling to the motor and/or associated power electronics by conveying refrigerant from the main loop to the motor or other power electronics.

<CIT> teaches a multi-stage compressing refrigeration device for multi-stage compression of a refrigerant using a plurality of compressing means. In the multi-stage compression refrigeration device, low-stage compressing means and high-stage compressing means, a condenser, first expanding means, an intermediate evaporator, second expanding means and a main evaporator constitute the refrigeration cycle. The refrigerant flowing out of the condenser is branched into the intermediate evaporator via the first expanding means and the main evaporator via the second expanding means. Heat exchange is performed between the refrigerant flowing into the second expanding means and the intermediate evaporator. Additionally, the refrigerant flowing out of the main evaporator is sucked by the low-stage compressing means, and the refrigerant flowing out of the intermediate evaporator is sucked by the high-stage compressing means together with the refrigerant discharged from the low-stage compressing means.

A refrigerant compressor according to an exemplary aspect of the present disclosure comprises a first stage and a second stage downstream of the first stage, and a cooling line configured to cool power electronics. The cooling line is configured to be switched between a first mode and a second mode. The first mode is configured to dump refrigerant between the first stage and the second stage, and the second mode is configured to dump refrigerant upstream of the first stage. The cooling line is configured to draw refrigerant from a main refrigerant loop.

In a further non-limiting embodiment of the foregoing refrigerant compressor, the compressor is a centrifugal compressor and the first stage comprises a first impeller and the second stage comprises a second impeller.

In a further non-limiting embodiment of the foregoing refrigerant compressor, a controller is configured to switch between the first and second modes automatically in response to an input from a sensor.

In a further non-limiting embodiment of the foregoing refrigerant compressor, the controller is configured to monitor a suction pressure of the compressor, and the controller is configured to automatically switch to the second mode when the suction pressure is above a predetermined threshold.

In a further non-limiting embodiment of the foregoing refrigerant compressor, the controller is configured to automatically direct the return of the cooling flow in a real time manner based on operating conditions.

In a further non-limiting embodiment of the foregoing refrigerant compressor, the cooling line is configured to be switched between the first mode and the second mode by inserting a plug along the cooling line.

In a further non-limiting embodiment of the foregoing refrigerant compressor, the compressor comprises a housing, and the plug is accessible external to the housing.

In a further non-limiting embodiment of the foregoing refrigerant compressor, the plug is a threaded plug.

In a further non-limiting embodiment of the foregoing refrigerant compressor, a directional flow control valve is configured to switch between the first mode and the second mode.

In a further non-limiting embodiment of the foregoing refrigerant compressor, the second mode is used for high saturated suction temperature (SST), or low pressure difference cooling applications.

A refrigerant system according to an exemplary aspect of the present disclosure comprises a main refrigerant loop in communication with a condenser, an evaporator, and a compressor according to the exemplary aspect of the present disclosure.

In a further non-limiting embodiment of the foregoing refrigerant system, the power electronics comprises a silicon controlled rectifier, and the cooling line comprises a heat exchanger arranged to cool the silicon controlled rectifier.

In a further non-limiting embodiment of the foregoing refrigerant system, a first plug is arranged in the heat exchanger.

In a further non-limiting embodiment of the foregoing refrigerant system, the cooling line is configured to be switched between the first mode and the second mode by inserting a plug along the cooling line.

In a further non-limiting embodiment of the foregoing refrigerant system, the compressor is arranged in a housing, and the plug is accessible external to the housing.

In a further non-limiting embodiment of the foregoing refrigerant system, a controller is configured to switch between the first and second modes automatically in response to an input from a sensor.

In a further non-limiting embodiment of the foregoing refrigerant system, the controller is set to direct the return of the cooling flow based on applications of normal comfort cooling or high SST cooling.

In a further non-limiting embodiment of the foregoing refrigerant system, the controller is configured to direct the return of the cooling flow in a real time manner based on operating conditions.

In a further non-limiting embodiment of the foregoing refrigerant system, the controller is configured to monitor a suction pressure of the compressor, and the controller is configured to automatically switch to the second mode when the suction pressure is above a predetermined threshold.

<FIG> schematically illustrates a refrigerant cooling system <NUM>. The refrigerant system <NUM> includes a main refrigerant loop, or circuit, <NUM> in communication with a compressor or multiple compressors <NUM>, a condenser <NUM>, an evaporator <NUM>, and an expansion device <NUM>. This refrigerant system <NUM> may be used in a chiller or heat pump, for example. Notably, while a particular example of the refrigerant system <NUM> is shown, this application extends to other refrigerant system configurations. For instance, the main refrigerant loop <NUM> can include an economizer downstream of the condenser <NUM> and upstream of the expansion device <NUM>. The refrigerant cooling system <NUM> may be an air condition system, for example.

<FIG> schematically illustrates an example compressor <NUM>. The example compressor <NUM> is a two-stage compressor. A first impeller <NUM> is upstream of a second impeller <NUM>. The example compressor <NUM> is a two stage centrifugal compressor. Other multiple-stage compressors may be utilized in other examples. In some examples, one stage includes an impeller and shroud arrangement, and another stage includes an alternative arrangement. The impellers <NUM>, <NUM> are driven by a motor <NUM>.

The compressor <NUM> may be a split cooling compressor. A first cooling line <NUM> draws refrigerant from the main refrigerant loop <NUM> (shown in <FIG>) for the power electronics, such as an insulated-gate bipolar transistor (IGBT) and a silicon controlled rectifier (SCR), for example. In the illustrated example, the cooling line <NUM> has a first heat exchanging portion <NUM> for cooling an IGBT and a second heat exchanging portion <NUM> for cooling an SCR. A second cooling line <NUM> from the main refrigerant loop <NUM> cools the motor <NUM>, for example. A first solenoid <NUM> may be in communication with a first controller <NUM> to control the fluid entering the first cooling line <NUM>. A second solenoid <NUM> may be in communication with a second controller <NUM> to control the fluid entering the second cooling line <NUM>. Although illustrated as two controllers <NUM>, <NUM>, it should be understood that a single controller may be used for both cooling lines <NUM>, <NUM>. The controller <NUM>, <NUM> may be a Bearing Motor compressor controller (BMCC). The controller <NUM> may be in communication with sensors <NUM>, <NUM> arranged along the cooling line <NUM>, for example. In the illustrated example, a first temperature sensor <NUM> provides a temperature at the motor windings and a second temperature sensor <NUM> provides a temperature at the motor cavity.

The cooling line <NUM> returns the refrigerant to the main refrigerant loop <NUM> near the compressor <NUM>. In this example, the cooling line <NUM> is selectable to return the refrigerant to one of at least two places at a juncture <NUM>. The cooling line <NUM> is configured in a first mode or a second mode. In the first mode, the cooling line <NUM> is configured to return refrigerant via a first line <NUM> that dumps refrigerant between the first and second impellers <NUM>, <NUM>. This is known as an inter-stage return, in some examples. In the second mode, the cooling line <NUM> is configured to return refrigerant via a second line <NUM> upstream of the first impeller <NUM>. The spot <NUM> may be the evaporator <NUM> or suction side of the compressor <NUM>.

The first and second modes may be selected manually or automatically. The first mode may be used for regular comfort cooling applications, while the second mode may be used for high SST cooling applications, such as data centers. In some examples, the controller <NUM> is used to switch between the first and second modes. The controller <NUM> may be in communication with sensors <NUM>, <NUM> arranged along the cooling line <NUM>, for example. In the illustrated example, a first temperature sensor <NUM> provides a temperature at the IGBT and a second temperature sensor <NUM> provides a temperature at the SCR. A directional flow control valve <NUM> is used to switch between the first mode and the second mode.

The controller <NUM> may monitor the suction pressure of the compressor <NUM>, in some examples. In some examples, the controller <NUM> will direct the valve <NUM> to return the refrigerant via the second line <NUM> if the suction pressure of the compressor <NUM> is above a preset value. This is the second mode with a suction return. If the suction pressure is below the preset value, the valve <NUM> will return the refrigerant via the first line <NUM>. This is the first mode inter-stage return. The first mode may be the default mode, for example.

The controller <NUM> may monitor the pressure difference in the cooling line and the temperature sensors <NUM> and <NUM> in real time. In case of low-pressure difference and the temperature sensor readings continuously above the set points, the controller <NUM> can direct the valve <NUM> to return to the second line <NUM>. If the pressure difference is enough to keep the temperature set points, it can direct the return to <NUM> to increase the total system efficiency.

<FIG> schematically illustrates another example compressor <NUM>. To the extent not otherwise described or shown, the compressor <NUM> corresponds to the compressor <NUM> of <FIG>, with like parts having reference numerals preappended with a "<NUM>.

In this example, the first line <NUM> may be blocked off by a threaded plug <NUM>, for example. The threaded plug <NUM> may be arranged in a silicon controlled rectifier (SCR) heat sink <NUM>. In this example, the second line <NUM> is an internal channel <NUM> with a customer connection plug <NUM>. A customer connection plug <NUM> may be used to control flow through the second line <NUM>. In one example, the customer connection plug <NUM> may be accessed external to a compressor housing, such that the customer may manually change between the first and second modes. The customer connection plug <NUM> may be used in combination with a separate threaded plug <NUM>, or without a separate plug.

In high SST applications, such as data centers cooling, the cooling line pressure difference may be lower than normal comfort cooling. Known cooling lines return refrigerant between the first and second compressor stages. However, for high SST applications, this known arrangement may not provide even cooling due to low pressure difference. The disclosed arrangement of returning refrigerant to the suction side may improve cooling for high SST applications, since the suction side has a lower temperature and pressure. The disclosed arrangement may also permit the cooling return to be selected based on a particular application or operating condition. Thus, the pressure difference and saturated temperature of the refrigerant are selectable. The disclosed arrangement may be used for data center cooling, for example. This arrangement may help prevent overheating and/or too much liquid in high SST applications.

<FIG> illustrate one example of manually switching between the first and second modes. <FIG> shows a view of an example compressor <NUM> in the first mode. In this example, a short plug <NUM> is used to block off the second line <NUM> (shown in <FIG>). The short plug <NUM> is thus used in the first mode, so the refrigerant is returned between the first and second stages via the first line <NUM>. The short plug <NUM> may be a threaded plug, for example.

<FIG> shows a view of an example compressor <NUM> in the second mode. In this example, a long plug <NUM> is used to block off the first line <NUM> (shown in <FIG>). The long plug <NUM> is thus used in the second mode, so the refrigerant is returned to the suction upstream of the first stage. The long plug <NUM> may be a threaded plug, for example.

In some examples, the compressor <NUM> may be shipped to a customer with both a short plug <NUM> and a long plug <NUM>. The customer can then decide whether to use the compressor <NUM> with the short or long plug <NUM>, <NUM>, depending on the application. In other examples, one of the first and second plugs <NUM>, <NUM> may be sold as a separate accessory to the compressor <NUM>. The plugs <NUM>, <NUM> provide a very simple, low cost way to have a single compressor <NUM> operable in two modes. In some examples, the customer decides which mode to use based on the application, and does not change between the first and second modes after the compressor <NUM> is installed.

Claim 1:
A refrigerant compressor (<NUM>), comprising:
a first stage (<NUM>) and a second stage (<NUM>) downstream of the first stage (<NUM>); characterized by
a cooling line (<NUM>) configured to cool power electronics, the cooling line (<NUM>) configured to be switched between a first mode and a second mode, wherein the first mode is configured to dump refrigerant between the first stage (<NUM>) and the second stage (<NUM>), and the second mode is configured to dump refrigerant upstream of the first stage (<NUM>),
wherein the cooling line (<NUM>) is configured to draw refrigerant from a main refrigerant loop (<NUM>).