Patent Application
20180111441
This invention relates generally to transport refrigeration systems and, more particularly, to supplying electrical power to all the power demand loads of the transport refrigeration unit while reducing engine fuel consumption.
Refrigerated trucks and trailers are commonly used to transport perishable cargo, such as, for example, produce, meat, poultry, fish, dairy products, cut flowers, and other fresh or frozen perishable products. A transport refrigeration system is mounted to the truck or to the trailer in operative association with a cargo space defined within the truck or trailer for maintaining a controlled temperature environment within the cargo space.
Conventionally, transport refrigeration systems used in connection with refrigerated trucks and refrigerated trailers include a transport refrigeration unit having a refrigerant compressor, a condenser with one or more associated condenser fans, an expansion device, and an evaporator with one or more associated evaporator fans, which are connected via appropriate refrigerant lines in a closed refrigerant flow circuit. Air or an air/gas mixture is drawn from the interior volume of the cargo space by means of the evaporator fan(s) associated with the evaporator, passed through the airside of the evaporator in heat exchange relationship with refrigerant whereby the refrigerant absorbs heat from the air, thereby cooling the air. The cooled air is then supplied back to the cargo space.
On commercially available transport refrigeration systems used in connection with refrigerated trucks and refrigerated trailers, the compressor, and typically other components of the transport refrigeration unit, must be powered during transit by a prime mover. In the case of refrigerated trailers, the prime mover typically comprises a diesel engine carried on and considered part of the transport refrigeration system. In mechanically driven transport refrigeration systems the compressor is driven by the diesel engine, either through a direct mechanical coupling or a belt drive, and other components, such as the condenser and evaporator fans are belt driven.
In conventional transport refrigeration system, the components of the refrigeration unit, such as the compressor for example, are mounted on a platform attached to the frame of the system by shock absorbers to limit the vibration transmitted to the components. The resulting system architecture is complex and includes a plurality of serviceable components that affect the reliability of the system.
According to an embodiment of the invention, a transport refrigeration unit configured to refrigerate a cargo space of a vehicle in which a perishable product is stored during transport is provided including a compressor having an electric compressor drive motor disposed therein for operating the compressor. A heat rejection heat exchanger and a heat absorption heat exchanger are fluidly coupled to the compressor. At least one fan assembly has at least one fan that is configured to provide an air flow over at least one of the heat rejection heat exchanger and the heat absorption heat exchanger. The transport refrigeration unit is configured to operate in a first mode and a second mode. At least one onboard power source is configured to produce sufficient power to operate the compressor drive motor and the at least one fan in the first mode. An external power source is configured to produce sufficient power to operate the compressor drive motor and the at least one fan in the second mode.
In addition to one or more of the features described above, or as an alternative, in further embodiments the first onboard power source includes a generator assembly coupled to a prime mover of the vehicle.
In addition to one or more of the features described above, or as an alternative, in further embodiments the prime mover is a diesel engine.
In addition to one or more of the features described above, or as an alternative, in further embodiments the generator assembly is directly coupled to the prime mover.
In addition to one or more of the features described above, or as an alternative, in further embodiments the generator assembly is indirectly coupled to the prime mover.
In addition to one or more of the features described above, or as an alternative, in further embodiments the generator assembly is indirectly coupled to the prime mover via at least one belt.
In addition to one or more of the features described above, or as an alternative, in further embodiments the generator assembly is indirectly coupled to the prime mover via a gearbox.
In addition to one or more of the features described above, or as an alternative, in further embodiments the generator assembly is configured to generate an alternating current.
In addition to one or more of the features described above, or as an alternative, in further embodiments an inverter operably is coupled to the generator assembly. The inverter is configured to convert the alternating current to a direct current.
In addition to one or more of the features described above, or as an alternative, in further embodiments a second onboard power source includes a battery system including one or more batteries.
In addition to one or more of the features described above, or as an alternative, in further embodiments when the transportation unit is operated in the second mode, the external power supply is configured to produce sufficient power to charge the battery system.
According to another embodiment of the invention, a method for operating a transport refrigeration system having a refrigeration unit configured to provide temperature conditioned air to a temperature controlled space, a prime mover, and an electricity generating device is provided including providing at least one onboard power source configured to provide sufficient power to operate the refrigeration unit. An external power source is determined to be operably coupled to the system. The system is operated in a first mode or a second mode. The at least one onboard power source is configured to operate the refrigeration unit in the first mode. The external power source is configured to operate the refrigeration unit in the second mode.
In addition to one or more of the features described above, or as an alternative, in further embodiments the at least one onboard power source includes electricity generating device driven by the prime mover.
In addition to one or more of the features described above, or as an alternative, in further embodiments at least one onboard power source includes a battery system including one or more batteries.
In addition to one or more of the features described above, or as an alternative, in further embodiments the external power source includes an external power grid coupled to an adapter of the transport refrigeration system.
In addition to one or more of the features described above, or as an alternative, in further embodiments the prime mover is a diesel engine and the electricity generating device is a generator.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
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:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
Referring now to the
A schematic diagram of a transport refrigeration system 20 according to an embodiment of the invention is illustrated in more detail in
The transport refrigerant unit 30 includes a refrigerant compression device 42, a refrigerant heat rejection heat exchanger 44, an expansion device 46, and a refrigerant heat absorption heat exchanger 48 connected in refrigerant flow communication in a closed loop refrigerant circuit and arranged in a conventional refrigeration cycle. The refrigeration unit 30 also includes one or more fans 50 associated with the refrigerant heat rejection heat exchanger 44 and driven by fan motor(s) 52 and one or more fans 54 associated with the refrigerant heat absorption heat exchanger 48 and driven by fan motor(s) 56. It is to be understood that a basic refrigeration unit is illustrated and described herein and other components (not shown) may be incorporated into the refrigerant circuit as desired, including for example, but not limited to, a suction modulation valve, a receiver, a filter/dryer, an economizer circuit.
The refrigerant heat rejection heat exchanger 44 may, for example, comprise one or more refrigerant conveying coiled tubes or one or more tube banks formed of a plurality of refrigerant conveying tubes extending between respective inlet and outlet manifolds. The fan(s) 50 are operative to pass air, typically ambient air, across the tubes of the refrigerant heat rejection heat exchanger 44 to cool refrigerant vapor passing through the tubes. The refrigerant heat rejection heat exchanger 44 may operate either as a refrigerant condenser, such as if the refrigeration unit 30 is operating in a subcritical refrigerant cycle, or as a refrigerant gas cooler, such as if the refrigeration unit 30 is operating in a transcritical cycle.
The refrigerant heat absorption heat exchanger 48 may, for example, also comprise one or more refrigerant conveying coiled tubes or one or more tube banks formed of a plurality of refrigerant conveying tubes extending between respective inlet and outlet manifolds. The fan(s) 54 are operative to pass air drawn from the temperature controlled cargo box across the tubes of the refrigerant heat absorption heat exchanger 48 to heat and evaporate refrigerant liquid passing through the tubes and cool the air. The air cooled in traversing the refrigerant heat rejection heat exchanger 44 is supplied back to the temperature controlled cargo box. It is to be understood that the term “air” when used herein with reference to the atmosphere within the cargo box includes mixtures of air with other gases, such as for example, but not limited to, nitrogen or carbon dioxide, sometimes introduced into a refrigerated cargo box for transport of perishable produce.
The refrigerant compression device 42 may comprise a single-stage or multiple-stage compressor such as, for example, a semi-hermetic compressor. The compression device 42 has a compression mechanism (not shown) driven by an electric motor 58. In one embodiment, the motor 58 is disposed internally within the compressor with a drive shaft interconnected with a shaft of the compression mechanism, all sealed within a common housing of the compression device 42.
A controller 60 is configured to control operation of the refrigeration system 20 including, but not limited to, operation of various components of the refrigerant unit 30 to provide and maintain a desired thermal environment within the cargo box of a truck or trailer, such as trailer 22 for example, that is within the temperature controlled space in which a perishable product is stowed. The controller 60 may be an electronic controller including a microprocessor and an associated memory bank. The controller 60 controls operation of various components of the refrigerant unit 30, such as the refrigerant compression device 42 and its associated drive motor 58, as well as the fan motors 50, 54, The controller 60 may also be configured to selectively operate the prime mover 70, typically through an electronic engine controller (not shown) operatively associated with the prime mover 70.
The refrigeration unit 30 has a plurality power demand loads, including, but not limited to, the compression device drive motor 58, the drive motor 52 for the fan 50 associated with the refrigerant heat rejection heat exchanger 44, and the drive motor 56 for the fan 54 associated with the refrigerant heat absorption heat exchanger 48. The power load demands of the transport refrigeration unit 30 may be powered exclusively by electric power from one or more onboard power source. The electricity generating device 74 driven by the prime mover 70 is the primary onboard power source for operating the transport refrigeration system 20. In some embodiments, as shown in
The prime mover 70, which typically comprises an on-board fossil-fuel engine, such as a diesel engine for example, drives the electricity generating device 74 that generates electrical power. In one embodiment, the electricity generating device 74 is directly coupled to the prime mover 70, such as the drive shaft of the engine for example. In other embodiments, the electricity generating device 74 is indirectly coupled to the prime mover 70, such as via one or more drive belts or a gearbox for example. The electricity generating device 74 may be an engine driven generator, configured to generate one of an alternating current (
The transport refrigeration system 20 is configured to operate in two different modes of operation: a first mode, also referred to as “road mode” and a second mode, also referred to as “standby mode.” The controller 60 is configured to control which power source is used to power the refrigeration unit 30 based on the selected mode of operation.
When the refrigeration system operates in the first “road mode”, the controller 60 is configured to select at least one of the prime mover 70 coupled to the electricity generating device 74 and the battery system 80 to supply power to meet the plurality of power demand loads of the transport refrigeration unit 30. The adapter 84 is only used to power the refrigeration unit 30 when the truck or trailer is parked at a truck stop, warehouse, or other facility, and the refrigeration system is operated in a “standby mode.” In such instances, the adapter 84 is connected to an external electrical power grid to supply grid power to the refrigeration unit 30, thereby permitting the controller 60 to shut down operation of the prime mover 70 and save fuel and any stored battery power. In addition, the power supplied from the electrical power grid may be used to recharge the battery system 80.
In some embodiments, additional systems that consume electrical power, such as a milk pump for example, are embedded into the transport refrigeration system 20. It is not always possible to connect these systems to the supply grid. Therefore, the refrigeration system 20 may additionally be configured to operate in a third mode where the electrical power grid is configured to supply power to the refrigeration unit 30, and the prime mover 70 is configured to operate the electricity generating device 74 to power an additional power connection 85 to energize these one or more external systems.
A transport refrigeration system 20 as described herein has various advantages. Fuel-savings are increased or maximized through a power management system that seamlessly transitions between available energy sources as required by the load. In addition, the overall system complexity is reduced and reliability is increased by eliminating serviceable mechanical components found in conventional systems, such as vibrasorbers for example.
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.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2015/000540 | 3/19/2015 | WO | 00 |
