Patent Description:
Power electronic devices such as motor drives can generate waste heat during operation based on the efficiency of the device. Additionally, when the power electronic devices heat up beyond some upper temperature limit, their efficiency can degrade. When configured into a refrigeration system, effective thermal integration of these devices can be an important aspect to the system's overall efficiency and reliability. Accordingly, there is a need to provide effective cooling to these power electronic devices.

<CIT> discloses a system, compressor, and method that cools an electronics module with a low-pressure refrigerant. The system, compressor, and method utilize a temperature sensor that detects a temperature of the low-pressure refrigerant and communicates with the electronics module. Based on the temperature detected by the temperature sensor, the electronics module controls a liquid dry out point of the refrigerant that is used to cool the electronics module.

According to a first aspect of the invention, a refrigeration unit according to claim <NUM> is provided.

According to a second aspect of the invention, a transport refrigeration system having a refrigeration unit according to any of claims <NUM> to <NUM> is provided.

According to a third aspect of the invention, a method of cooling a power electronic device during operation of a refrigeration unit according to claim <NUM> is provided.

The following descriptions as provided by way of example only, and should not be considered limiting in any way.

With reference now to <FIG> and <FIG>, an exemplary transport refrigeration system <NUM> is illustrated. In the illustrated, non-limiting embodiment, the transport refrigeration system <NUM> is shown as a trailer system. As shown, the transport refrigeration system <NUM> includes a trailer or container <NUM> being towed or otherwise transported by a tractor <NUM> including an operator's compartment or cab <NUM> and also including prime mover (not shown), such as an engine or HVDC battery pack, which acts as the drivetrain system of the transport refrigeration system <NUM>. A refrigeration unit <NUM> is configured to maintain cargo located within the container <NUM> at a selected temperature by cooling the cargo space of the container <NUM>. As shown, the refrigeration unit <NUM> may be mounted at the front wall <NUM> of the container <NUM>. Together, the refrigeration unit <NUM> and the cargo container <NUM> may form a refrigerated container system. It should be appreciated by those of skill in the art that embodiments described herein may be applied to any transport refrigeration system such as, for example shipping containers that are shipped by rail, sea (via a watercraft), or any other suitable container, without use of a tractor <NUM>.

With reference to <FIG>, a basic refrigeration circuit of the refrigeration unit <NUM> is shown. The refrigeration unit <NUM> is divided into two sections, a condenser section 30a and an evaporator section 30b. The condenser section 30a may be disposed generally forward of a front wall of the container <NUM> and is arranged in fluid communication with the ambient atmosphere external to the container <NUM> and the refrigeration unit <NUM> to exchange air and heat therewith. The evaporator section 30b is not in fluid communication with the ambient atmosphere to control temperature within the container <NUM>. The refrigeration unit <NUM> includes a compressor <NUM>, a condenser coil <NUM>, an expansion device <NUM>, and an evaporator coil <NUM> fluidly connected to one another to form a closed loop system. A fluid R, such as a refrigerant, for example, is configured to flow from the compressor <NUM> to the condenser coil <NUM>, expansion device <NUM>, and evaporator coil <NUM> in series. A condenser fan <NUM>, such as driven by a condenser motor (not shown) is configured to move a flow of air across an exterior of the condenser coil <NUM>, and an evaporator fan <NUM>, such as driven by an evaporator motor (not shown), may be used to drive a flow of fluid (air) across an exterior of the evaporator coil <NUM> and into the portion of the container <NUM> in which the cargo is located.

At least one power electronic device <NUM> (see <FIG>) associated with the compressor <NUM> may be mounted within the condenser section 30a, such as near or adjacent to the compressor <NUM>, for example. It should be understood that the term "power electronic device" as used herein can refer to any electronic component which can provide a controlled output power by modulating and/or converting a supplied input power (e.g., a variable frequency drive, power rectifier, power converter, and the like). Such a power electronic device <NUM> can be used to control the speed of a compressor and/or the speed of the fan of a refrigeration system based on various predetermined system conditions. As shown, at least one power electronic device <NUM> may be mounted to a vertically oriented first surface <NUM> of a mounting plate <NUM>. However, embodiments where a power electronic device <NUM> is mounted to a surface having a non-vertical orientation, such as a horizontal surface for example, are also within the scope of the disclosure.

The reliability and life of the one or more power electronic devices <NUM> can depend upon precluding such electrical components from operating at high temperatures and/or precluding their exposure to thermal shock. During operation of the refrigeration unit <NUM>, the electrical components inside the power electronic devices <NUM> generate a waste heat. In an embodiment, to maintain the power electronic devices <NUM> at a suitable temperature, the refrigeration unit <NUM> includes a heat sink <NUM> configured to remove heat from the power electronic devices <NUM>. The heat sink <NUM> may be formed from any suitable thermally conductive material, such as aluminum or copper for example. In an embodiment, the heat sink <NUM> is formed via an extrusion process. Further, the heat sink <NUM> may include an insulative material (not shown) arranged over all or at least a portion of an exterior surface thereof.

As shown, a first end <NUM> of the heat sink <NUM> is mechanically and thermally coupled to a second, opposite surface <NUM> of the mounting plate <NUM>, such as the surface opposite the surface <NUM> to which the power electronic devices <NUM> are connected. Although the heat sink <NUM> is illustrated as extending substantially orthogonal to the surface <NUM> of the mounting plate <NUM>, embodiments where all or a portion of the heat sink <NUM> extends at another angle are also contemplated herein.

In an embodiment, the first end <NUM> of the heat sink <NUM> is mounted in overlapping arrangement with the surface <NUM> of the mounting plate <NUM>. However, in other embodiments, at least a portion of the first end <NUM> of the heat sink <NUM> is receivable within at least one recess or groove (not shown) formed in the surface <NUM> of the mounting plate <NUM>. Further, a material, such as thermal grease for example, may be arranged at the interface between the heat sink <NUM> and the mounting plate <NUM> to facilitate heat transfer away from the mounting plate <NUM> to the heat sink <NUM>, and therefore away from the power electronic devices <NUM>. Although the mounting plate <NUM> is described as a plate, it should be understood that in an embodiment, the mounting plate may be a housing having an internal flow path for a cooling fluid such that the mounting plate functions as a heat exchanger.

In an embodiment, the heat sink <NUM> is configured to transfer heat from the power electronic devices <NUM> via the mounting plate <NUM> to another component within the condenser section 30a. As best shown in <FIG>, a clearance <NUM> is defined between the compressor <NUM> and the surface <NUM> of the mounting plate <NUM>. A conduit <NUM>, also referred to herein as the "suction tube", fluidly connecting the suction inlet <NUM> of the compressor <NUM> with an upstream component, such as an outlet of the evaporator coil <NUM> for example, is arranged at least partially within the clearance <NUM>. In the illustrated, non-limiting embodiment, the heat sink <NUM> is mechanically and thermally coupled to a portion of the suction tube <NUM>. During operation of the refrigeration unit <NUM>, the temperature of the suction tube <NUM> (which may be considered equivalent to the temperature of the refrigerant within the suction tube <NUM>) is much lower than the operating temperature of the one or more power electronic devices <NUM>. Accordingly, a heat sink <NUM> arranged in thermal communication with both the mounting plate <NUM> and the suction tube <NUM> will facilitate enhanced cooling of the power electronic devices <NUM>.

In the illustrated, non-limiting embodiment, the heat sink <NUM> is coupled to a linear section <NUM> of the suction tube <NUM>. The linear section <NUM> of the suction tube <NUM> may be vertically oriented (as shown), or alternatively, may arranged parallel to or at an angle to the surface <NUM> of the mounting plate <NUM>. A height of the heat sink <NUM>, measured parallel to the axis of the linear section <NUM> of the suction tube <NUM> to which the heat sink <NUM> is coupled, may be substantially equal to, or may be less than the length of the corresponding linear section <NUM> of the suction tube <NUM>. As shown, the suction tube <NUM> includes a single linear section <NUM> arranged within the clearance <NUM>. However, it should be understood that a suction tube <NUM> having a tortuous path including a plurality of linear sections arranged within the clearance <NUM> is also contemplated herein. In such embodiments, the heat sink <NUM> may be configured to couple to at least one linear section of the plurality of linear sections <NUM> of the suction tube <NUM> depending on the desired heat dissipation. Accordingly, the configuration of the suction tube <NUM> within the clearance <NUM> and/or the total surface area over which the heat sink <NUM> is arranged in contact with the suction tube <NUM> may be selected based on the temperature demands of the power electronic devices <NUM> of a specific application.

As shown, the second end <NUM> of the heat sink <NUM> is connected to the suction tube <NUM>. In an embodiment, the second end <NUM> of the heat sink <NUM> includes a flange <NUM> having a recess or groove <NUM> complementary to a contour of a portion of the suction tube <NUM>. A mounting bracket <NUM> having a similar flange <NUM> and a recess <NUM> for receiving a portion of the suction tube <NUM> therein may be connectable with the flange <NUM> of the heat sink <NUM>, such as via a plurality of fasteners for example, to affix the heat sink <NUM> to the suction tube <NUM>. Although the second end <NUM> of the heat sink <NUM> is shown in the illustrated, non-limiting embodiments as being coupled to the suction tube <NUM>, it should be understood that embodiments where the suction tube <NUM> is arranged at another location relative to the heat sink <NUM>, such as at a central portion of the heat sink <NUM> for example, are also contemplated herein.

In an embodiment, a width of the heat sink <NUM> at the first end <NUM>, measured in plane perpendicular to the length of the heat sink <NUM>, is substantially larger than a width of the heat sink <NUM> at the second end <NUM> thereof. The heat sink <NUM> may be formed having a generally solid body, as shown in <FIG> and <FIG>. However, in other embodiments, the heat sink <NUM> may have one or more openings <NUM> formed therein to reduce the total material and weight of the heat sink <NUM>, while maintaining the necessary heat transfer from the mounting plate to the suction tube <NUM>. The openings <NUM> formed in the heat sink <NUM> may extend along one or more of the length and width of the heat sink <NUM>. As a result of the openings <NUM>, the body of the heat sink <NUM> may have a finned configuration. For example, in the illustrated, non-limiting embodiment of <FIG> and <FIG>, the first end <NUM> of the heat sink <NUM> is not a continuous surface, but rather is defined by the ends of a plurality of fins, at least one of which is in contact with the mounting plate <NUM>.

Inclusion of a heat sink <NUM> as described herein will enhance the cooling of the power electronic devices of the refrigeration unit, thereby improving component performance, reliability, and life. In addition, transferring the waste heat from the power electronics devices to the refrigerant in the suction tube <NUM> may also extend the range of ambient operation of the refrigeration unit <NUM>.

Claim 1:
A refrigeration unit (<NUM>) comprising:
a refrigeration circuit including a compressor and a suction tube (<NUM>) connected to an inlet of the compressor;
a mounting plate (<NUM>) having a first surface (<NUM>) and a second, opposite surface (<NUM>), a clearance being defined between the compressor and the second surface, wherein a portion of the suction tube is arranged within the clearance;
a power electronics device (<NUM>) thermally coupled to the first surface (<NUM>) of the mounting plate;
a heat sink (<NUM>) having a first end (<NUM>) thermally and mechanically coupled to the second surface (<NUM>) of the mounting plate and having a second end (<NUM>) thermally and mechanically coupled to the portion of the suction tube (<NUM>) arranged within the clearance, wherein the heat sink is configured to transfer waste heat from the mounting plate to the suction tube.