BACKGROUND OF THE INVENTION

[0001] In today's world, a wide variety of goods are transported via trucks, trailers and other mobile containers. Often, it is necessary to control the environment within such mobile containers. For example, it is often desirable to control the temperature and or humidity within a container. It may also be advantageous to provide for circulation the air within a container, to exchange air within a container with ambient air from outside, or to introduce other gases such as ozone, carbon dioxide, or nitrogen into a shipping container so as to maintain a desired environment within the container.

[0002] To meet these desires, mobile containers typically make use of a transport refrigeration unit, which may be attached to a mobile container. Typically transport refrigeration units include a power source, such as a diesel engine. They also include a refrigerant loop that includes a compressor for circulating refrigerant through an evaporator and a condenser and one or more blowers for circulating air into and within the container and for facilitating exchange of heat with the refrigerant loop. A generator is often included to produce electricity to power the fans, and in some cases, a battery is also included for storing energy to enable the fans to operate when the diesel engine is not operating.

[0003] There is a need for a transport refrigeration unit with reduced fuel consumption, reduced ownership cost, and decreased size.

BRIEF DESCRIPTION OF THE INVENTION

[0004] An integrated transport refrigeration unit comprises an engine providing power to drive a shaft. The shaft drives a refrigerant compressor and a generator, both of which are encased within a housing, and the generator is immersed in refrigerant. In an exemplary embodiment, an integrated transport refrigeration unit also includes an auxiliary generator driven by the shaft and disposed externally from the housing. In this embodiment, the auxiliary generator produces current for charging a battery and for operating a fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0006] FIG. 1 is a perspective drawing of an integrated transport refrigeration unit with an immersed generator disposed between the engine and the compressor;

[0007] FIG. 2 is a perspective drawing of an integrated transport refrigeration unit with a compressor disposed between the engine and the immersed generator;

[0008] FIG. 3 is a schematic diagram showing an exemplary integrated transport refrigeration unit with a high-voltage, alternating-current fan;

[0009] FIG. 4 is a schematic diagram showing an exemplary integrated transport refrigeration unit with a combination of direct-current and alternating-current fans; and

[0010] FIG. 5 is a schematic diagram showing an exemplary integrated transport refrigeration unit with a combination of direct-current and alternating-current fans and an integrated, high-voltage battery pack.

DETAILED DESCRIPTION OF THE INVENTION

[0011] With reference to the drawings, FIG. 1 is a perspective drawing of an integrated transport refrigeration unit 100 with an immersed generator 110 disposed between an engine 120 and a compressor 130. In accordance with this embodiment, engine 120 is an internal combustion engine, such as a diesel or gasoline engine, and drives an output shaft (not shown), to which immersed generator 110 and compressor 130 are directly coupled. The drive shaft may be open to the atmosphere or it may be magnetically driven. Housing 140 encases both compressor 130 and immersed generator 110 and seals a volume of refrigerant within housing 140. Refrigerant inlet 150 carries refrigerant to housing 140 for uptake and re-compression by compressor 130, and refrigerant outlet 160 delivers re-compressed refrigerant to a high pressure coolant line for expansion in an evaporator (not shown). [0012] Within housing 140, both compressor 130 and generator 110 are immersed in low-pressure refrigerant that has been returned to housing 140 via refrigerant inlet 150. Being immersed, compressor 130 and generator 110 are cooled by the refrigerant. It should be noted that housing 140 is sealed so as to retain refrigerant, and generator 110 is constructed using magnet wire or another wire suitable for immersion in refrigerant. In a exemplary embodiment, a single shaft is driven by engine 120, and permanent magnets are fixed to the shaft. Windings are disposed within housing 140 and around the permanent magnets. As the shaft is rotated by the engine, current is generated in the windings. In another exemplary embodiment, an induction generator is disposed on the drive shaft wherein an alternating current is induced as a consequence of the rotation of the shaft. In both cases, compressor 130 is also driven by the shaft, and comprises a series of pistons cycled by the rotation of the shaft. As a result of the incorporation of the generator within the housing, the transport refrigeration unit may be made more compact as space is no longer required to position a generator on an auxiliary shaft. In addition, the generator can be made smaller due to decreased need to entrain air to cool the generator.

[0013] FIG. 2 is a perspective drawing of an integrated transport refrigeration unit

200 with a compressor 230 disposed between the engine 220 and the immersed generator 210. Accordingly, generator 210 is outboard of compressor 230. As with the transport refrigeration unit of FIG. 1, generator 210 and compressor 230 are directly coupled to the output of engine 220. Housing 240 surrounds compressor 230 and immersed generator 210 and seals a volume of refrigerant within housing 240. Refrigerant is reserved within housing 240 for uptake and re-compression by compressor 230, and both compressor 230 and generator 210 are immersed in low-pressure refrigerant that has been returned to housing 240. Thus, compressor 230 and generator 210 are cooled by the refrigerant. Also, housing 240 is sealed to retain refrigerant, and generator 210 is constructed for immersion in refrigerant. As with the embodiment shown in FIG. 1, the incorporation of the generator within the housing enables the transport refrigeration unit to be made more compact as space is no longer required to position a generator on an auxiliary shaft. In addition, the generator can be made relatively smaller due to decreased need to entrain air to cool the generator.

[0014] FIG. 3 is a schematic diagram showing an exemplary integrated transport refrigeration unit 300. In this embodiment, engine 320 drives integrated compressor/generator unit 310 with a single shaft 330. Integrated compressor/generator unit 310 is sealed within a single housing (not shown in FIG. 3) that also serves as a low pressure reservoir for refrigerant that is returned to the compressor after the refrigerant has flowed through a typical refrigeration cycle such as having passed through a condenser and an evaporator for extracting heat from a cooled space. In this embodiment, shaft 330 also drives an auxiliary generator 340 using belt 350 or other means for extracting power from shaft 330. The auxiliary generator 340 is disposed externally from the single housing that serves as a low pressure reservoir for refrigerant returned to the compressor. In an exemplary embodiment, auxiliary generator 340 is an alternator coupled with a rectifier (i.e., a DC alternator) so as to produce DC current for charging unit battery 360 and current may also be made directly available to control box 370. Control box 370 may draw electrical current directly from battery 360 when engine 320 is not operating or may draw power from auxiliary generator 340 when engine 320 is operating. Control box 370 includes an inverter (not shown) for converting DC current to alternating current at a voltage suitable for operating at least one fan 380, which provides ventilation, circulation, heat transfer for a transportable container.

[0015] In operation, control box 370 may receive indications from the transportable container to determine whether and how to operate fan 380 and/or compressor 310. When it is desirable to operate fan 380, control box 370 may draw power from battery 360 so long as it retains adequate charge. When a state of charge in battery 360 is insufficient to operate fan 380, control box 370 may command engine 320 to operate so as to provide power via compressor/generator 310 and to re-charge unit battery 360. Similarly, when it is desirable to provided cooling to the transportable container, control box 370 may command engine 320 to operate so as to provide cooling by pumping refrigerant through its refrigeration cycle components. While engine 320 is operating, compressor/generator 310 produces power to operate fan 380, and alternator 340 produces power to charge battery 360.

[0016] FIG. 4 is a schematic diagram showing an exemplary integrated transport refrigeration unit 400 with a combination of direct-current and alternating-current fans. In this embodiment, engine 420 drives integrated compressor/generator unit 410 with a single shaft 430. Integrated compressor/generator unit 410 is sealed within a single housing (not shown) that also serves as a low pressure reservoir for refrigerant that is returned to the compressor after the refrigerant has flowed through a typical refrigeration cycle such as having passed through a condenser and an evaporator for extracting heat from a cooled space. In this embodiment, shaft 430 also drives auxiliary generator 440 using belt 450 or other means for extracting power from shaft 430. Auxiliary generator 440 may include an alternator coupled to a rectifier for producing DC current (i.e., a DC alternator) for charging unit battery 460 and current may also be made directly available to control box 470. Control box 470 may draw electrical current directly from battery 460 when engine 420 is not operating or may draw power from auxiliary generator 440 when engine 420 is operating. Control box 470 includes an inverter (not shown) for converting DC current to alternating current at a voltage suitable for operating condenser fans 480, which provide heat transfer for a transportable container. Control box 470 also provides power to converter 490 for providing DC current at a voltage suitable for operating evaporator fans 495, which provide heat transfer for a transportable container.

[0017] Accordingly, this embodiment enables power to be delivered in various forms to drive different components. This can be useful in mobile refrigeration applications such as where it may be advantageous to employ direct current power to drive evaporator components, while it may be preferable to employ alternating current power to drive condenser components. Alternating current produced by the compressor/generator can be used to drive the condenser fan, while the auxiliary generator may be configured to provide DC power to drive the evaporator fan. Accordingly, this embodiment may be configured so as to eliminate any need for a separate rectifier device, thereby saving unit volume, weight, and cost.

[0018] FIG. 5 is a schematic diagram showing an exemplary integrated transport refrigeration unit 500 with a combination of direct-current and alternating-current fans and an integrated high voltage battery pack. In this embodiment, engine 520 drives integrated compressor/generator unit 510 with a single shaft 530. Integrated compressor/generator unit 510 is sealed within a single housing (not shown) that also serves as a low pressure reservoir for refrigerant that is returned to the compressor following its having flowed through a typical refrigeration cycle such as having passed through a condenser and an evaporator for extracting heat from a cooled space. In this embodiment, shaft 530 also drives auxiliary generator 540 using belt 550 or other means for extracting power from shaft 530. Auxiliary generator 540 produces DC current for charging unit battery 560 and current may also be made directly available to control box 570. In addition, compressor/generator 510 produces high voltage current for use by a battery pack charger 512 to charge high voltage battery pack 514. Power stored in high voltage battery pack 514 can then be used by control box 570.

[0019] Control box 570 may draw electrical current directly from battery 560 or from high voltage battery pack 514 when engine 520 is not operating. In an exemplary embodiment, high voltage battery pack may be a commercial battery pack that generates approximately 600 volts. When engine 520 is driving the system, control box 570 may also draw power from auxiliary generator 540 or from compressor/generator 510, which is configured to produce high voltage current. Control box 570 provides power to AC/DC converter 580, which produces power or current at a sufficiently high voltage to drive high- voltage, direct-current fans 590. When engine 520 is not operating, power from high voltage battery pack 514 may be used to drive compressor 510.

[0020] While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.