Transport refrigeration unit with cooling and chilling circuit and commercial vehicle with transport refrigeration unit

Description

[0001] The invention relates to a transport refrigeration unit for cooling the body of a commercial vehicle, in particular a truck, trailer or semi-trailer, comprising a refrigeration circuit for circulating a refrigerant, an electronic unit for operating the refrigeration circuit and a cooling circuit for cooling the electronic unit, wherein the refrigeration circuit comprises an evaporator for evaporating the refrigerant, a compressor for compressing the refrigerant evaporated in the evaporator, a condenser for condensing the refrigerant compressed in the compressor and an expansion valve for the refrigerant condensed in the condenser, wherein the cooling circuit comprises a coolant, a pump for circulating the coolant in the cooling circuit and a cooler for cooling the coolant and wherein the condenser and the cooler are arranged in a direction of flow for cooling air.Furthermore, the invention relates to a commercial vehicle, in particular a truck, trailer or semi-trailer, with a box body and a transport refrigeration machine provided on an end wall of the box body for cooling at least one cargo space provided in the box body.

[0002] Commercial vehicles, such as trucks, trailers, and semi-trailers, are primarily designed for transporting goods, preferably general cargo, on public roads. For this purpose, commercial vehicles have various types of superstructures that serve to accommodate the goods being transported in a cargo space.

[0003] For example, there are tarpaulin-covered bodies where the side walls and roof are closed by at least one tarpaulin section. The front wall of tarpaulin-covered bodies is usually a solid wall, while the rear wall is typically formed by two hinged doors to allow loading from the rear when needed. If a tarpaulin section can be moved along the side wall, these are also called curtain-sided vehicles.

[0004] In addition to tarpaulin-covered bodies, box bodies with fixed side walls, a fixed front wall, and a fixed roof, which enclose the cargo space, are also common. Because box bodies are enclosed, they are particularly suitable for transporting moisture-sensitive and / or temperature-sensitive goods, for example, for so-called dry transport and / or refrigerated transport. The rear wall of box bodies is usually closed by two hinged doors or a roller door.

[0005] Box bodies often feature double-walled panels on the front, roof, and / or side walls. These panels comprise an outer and an inner structural layer, as well as a core layer in between, typically made of foamed plastic. The inner and / or outer layers themselves can be multi-layered as needed. Due to the high thermal insulation provided by the foamed plastic core, these box bodies are suitable for transporting cargo requiring refrigeration. For this purpose, refrigeration units are mounted on the front walls of the box bodies. These units draw air from the cargo area, cool it, and then blow the cooled air back into the cargo area.In order to cool several zones of the cargo space independently of each other as required, so-called ceiling evaporators can be provided on the ceiling in corresponding zones of the cargo spaces, which are supplied with refrigerant by the transport refrigeration machine.

[0006] Transport refrigeration units are typically enclosed by a housing on the front wall, both at the front and to the sides. These units also incorporate a refrigeration circuit with an evaporator. In the evaporator, a refrigerant, previously expanded through a throttle, is evaporated, absorbing heat from the air in the cargo space via a heat exchanger surface. The refrigerant is then compressed and condensed in a condenser, which also features a heat exchanger surface to dissipate the heat released during condensation to the surrounding environment.

[0007] The cooling circuit, on the other hand, comprises a pump for circulating a coolant within the circuit and a radiator for dissipating the heat absorbed by the electronics from the coolant to the surroundings. To dissipate heat via the condenser and radiator, the condenser and radiator are positioned within the transport refrigeration unit in such a way that they are exposed to a flow of cooling air. This airflow can be forced by the vehicle's movement or by at least one fan.

[0008] An example of a transport refrigeration machine is shown in document WO 2014 / 047401 A1.

[0009] Positioning the condenser in the direction of the cooling airflow, upstream of the cooler, is intended to ensure both high cooling capacity from the transport refrigeration unit and adequate cooling of the electronics unit. However, further improvements are needed in this regard, especially as transport refrigeration units are increasingly electrically powered and therefore subject to different requirements.

[0010] Therefore, the present invention is based on the objective of designing and further developing the transport refrigeration machine and the commercial vehicle of the type mentioned above and explained in more detail above in such a way that improved heat management can be achieved.

[0011] This problem is solved in a transport refrigeration machine according to the preamble of claim 1 by the fact that the cooler is provided at least sectionally in front of at least one section of the condenser when viewed in the direction of flow of the cooling air.

[0012] The aforementioned problem is further solved in a commercial vehicle according to the preamble of claim 10 by the fact that the transport refrigeration unit is designed according to one of claims 1 to 9.

[0013] By positioning the cooler in the direction of the cooling airflow, at least partially upstream of at least part of the condenser, a higher cooling capacity is provided for the electronic unit without unduly impairing the cooling capacity of the condenser. This represents a departure from the previous design of transport refrigeration units, and it has been shown that this innovation leads to improved cooling of the transport refrigeration unit overall. Such transport refrigeration units also have the advantage of a very compact design compared to transport refrigeration units in which the condenser and cooler are arranged side-by-side in the airflow to improve overall cooling capacity.

[0014] The air used for cooling is preferably the ambient air surrounding the transport refrigeration unit. During transport, the airflow from the vehicle is therefore suitable as cooling air, which can be directed to the radiator and condenser by a suitable design of the transport refrigeration unit. For this purpose, the housing of the transport refrigeration unit, for example, has suitable cooling air inlets.

[0015] Regarding the electronic unit, it should be noted that the term "electronics" used here is not necessarily intended to imply a distinction from the term "electrical." Rather, the electronic unit is understood to be, in particular, a unit that comprises at least one electronic assembly and / or at least one electrical assembly. According to the invention, it is therefore not essential whether the electronic unit actually comprises electronic or electrical assemblies. More generally, the electronic unit can be housed in an electronic enclosure, which may, in fact, be at least partially an electrical enclosure.For the sake of clarity and to avoid unnecessary repetition, the following text will consistently refer to an electronic unit and an electronic housing, even though the term "electronics" here does not necessarily have to be understood in the classical sense. Furthermore, the electronic housing can also be considered a type of control cabinet, in which the corresponding assemblies are grouped and connected to assemblies outside the electronic housing and, if necessary, also outside the transport refrigeration unit.

[0016] In a first particularly preferred embodiment of the transport refrigeration unit, the electronic unit comprises at least one charger and / or at least one frequency converter. These components are of particular importance in the design of electrically operated transport refrigeration units, since electric transport refrigeration units are powered by a battery, and the operation of the transport refrigeration unit requires an alternating voltage, even though the battery provides a direct voltage. It has also been found that chargers and / or frequency converters heat up considerably during operation of the transport refrigeration units and therefore require reliable and intensive cooling to remain efficient. Consequently, the advantages achievable according to the invention are particularly evident in a corresponding transport refrigeration unit.

[0017] The same applies to transport refrigeration units, whose chargers include a charge controller and a power supply. The charge controller ensures that the battery is charged in a predetermined manner, while the power supply converts and stabilizes the voltage to a different level than that used for charging. For example, the battery can be charged using a voltage drawn from an external power grid or a voltage generated by the vehicle itself while driving.

[0018] Regarding the frequency converter, it is advantageous, either as an alternative or in addition, if the frequency converter is bidirectional. In this case, the frequency converter can, for example, convert the DC voltage from the battery into an AC voltage for operating the transport refrigeration unit, and also convert the AC voltage back into a DC voltage for charging the battery.

[0019] To increase the cooling capacity of the radiator and condenser, it is advantageous to arrange them on the intake side of at least one fan. The fan, preferably an axial fan that provides a high volume flow rate while requiring little space, ensures a sufficient flow of cooling air through the radiator and condenser at all times. Since the radiator and condenser are arranged on the intake side of the at least one fan, the cooling air is drawn through them. However, this principle could also be reversed by arranging the radiator and condenser on the pressure side of the at least one fan. The at least one fan can be part of a fan unit, particularly when more than one fan is used.

[0020] For cooling with air, a simple and particularly effective design is achieved when the cooler and / or condenser is formed primarily from interconnected, parallel, and spaced-apart tubes. Tube bundle heat exchangers are especially suitable for this purpose. To increase the heat exchange surface area while maintaining a compact design, the parallel tubes of the cooler and / or condenser can be arranged in several planes, one behind the other, in the direction of airflow.

[0021] It has also proven particularly practical and space-saving if the planes of the cooler and condenser formed by the parallel pipes are arranged parallel to each other. Thus, the cooler and condenser have parallel planes of cooling pipes as needed. For efficiency reasons, the planes of cooling pipes are additionally or alternatively aligned at least substantially perpendicular to the direction of flow.

[0022] For a compact yet efficient design of the transport refrigeration unit, it is advantageous if the cooler and condenser are arranged, at least substantially, overlapping each other in the direction of airflow. If, additionally or alternatively, the condenser is positioned only partially behind the cooler in the direction of airflow, the remaining part of the condenser can be directly cooled by the airflow without the air first passing through the cooler and thus being heated. This ensures sufficient cooling of the condenser.

[0023] To provide a transportable refrigeration unit with compact dimensions, it is advantageous for the cooler and condenser to have at least essentially the same width. The cooler can then simply be positioned partially overlapping the condenser. However, to ensure at least a partially direct airflow to the condenser in the direction of airflow, it may be beneficial for the cooler and condenser to have different heights.

[0024] From a fundamental efficiency and cost perspective, it is generally advisable for the coolant in the cooling circuit to be at least essentially water, and for the refrigerant in the refrigeration circuit to preferably be a synthetic refrigerant.

[0025] In a first, particularly preferred embodiment of the commercial vehicle, a battery is provided, especially beneath the box body, to supply power to the transport refrigeration unit and / or to store electrical energy. In this case, it is not necessary to operate an internal combustion engine to drive a generator. The internal combustion engine and generator can be dispensed with. Instead, the transport refrigeration unit can be operated purely electrically. With such transport refrigeration units, the advantages described above are particularly pronounced.

[0026] If a three-phase power outlet, such as a CEE32 socket, or a three-phase power plug, such as a CEE32 plug, is provided on the transport refrigeration unit or on the commercial vehicle, the three-phase power outlet can be used to operate the transport refrigeration unit while the commercial vehicle is stationary. Simultaneously or alternatively, the power supply can be used via an external power grid to store electrical energy in the battery.

[0027] If the commercial vehicle has an axle coupled to a generator to drive the generator and produce electricity while the vehicle is in motion, the electricity generated can be fed into the transport refrigeration unit via the frequency converter. The frequency converter then generates either alternating current at a predetermined voltage and frequency to operate the refrigeration unit, or direct current to charge the vehicle's battery.

[0028] For efficiency reasons, it is preferred if the voltage between the battery, the charger and / or the frequency converter is between 500 V and 900 V, preferably between 600 V and 800 V, and in particular between 650 V and 750 V.

[0029] The invention will now be explained in more detail with reference to a drawing that illustrates only one embodiment. The drawing shows Fig. 1 shows a commercial vehicle according to the invention, towed by a tractor unit and equipped with a transport refrigeration unit according to the invention, in a perspective view; Fig. 2 shows a front view of the front wall of the commercial vehicle. Fig, 1 with the transport refrigeration machine, Fig. 3, detail III of the transport refrigeration machine according to Fig. 2 in a perspective view and Fig. 4 a flow diagram concerning the transport refrigeration machine from Fig. 2 and the commercial vehicle from Fig. 1 .

[0030] In the Fig. 1 Figure 1 depicts a commercial vehicle 1 in the form of a semi-trailer, towed by a tractor unit Z. The commercial vehicle 1 comprises a chassis 2 and a running gear 3 attached to it, comprising three separate axles 4. A box body 5 with a fixed front wall 6, a fixed roof 7, fixed rear doors 8 on a rear wall 9, and fixed side walls 10 is also supported by the chassis 2. The front wall 6, the side walls 10, and the roof 7 are formed by panels (not shown in detail) which have an outer and an inner layer, between which a core layer made of foamed plastic is provided. The inner and outer layers are structural layers, which may also each be multi-layered. The core layer primarily serves as thermal insulation for a cargo space 11 provided in the box body 5.

[0031] In order to cool down the cargo space 11 of the box body 5, a vent is installed on the front wall 6, particularly in the Fig. 2 The transport refrigeration unit 12, as shown, is mounted and enclosed in a housing 13. Air is drawn in from the cargo space 11 by the transport refrigeration unit 12, cooled, and blown back into the cargo space 11. For this purpose, the transport refrigeration unit 12 has a refrigeration circuit 14 (not shown in detail), which is generally known and is also provided in principle in other transport refrigeration units 12. A refrigerant circulates in the refrigeration circuit 14, from which heat can be absorbed and released elsewhere. The refrigeration circuit comprises an evaporator for evaporating the refrigerant, a compressor for compressing the refrigerant evaporated in the evaporator, a condenser 15 for condensing the refrigerant compressed in the compressor, and an expansion valve upstream of the evaporator for expanding the refrigerant condensed in the condenser 15.As the refrigerant evaporates, it absorbs heat from the air in the cargo space 11, which is then released back into the environment in the condenser 15 when the refrigerant condenses. A compressor is provided to drive the refrigeration cycle 14 and to increase the refrigerant's pressure. To reduce the refrigerant's pressure and allow it to evaporate again, a throttle valve is provided, which in this specific case may be an expansion valve.

[0032] The transport refrigeration unit 12 comprises, in addition to the refrigeration circuit 14, a cooling circuit 16 which serves not to cool the cargo space 11, but to cool the transport refrigeration unit 12 itself, specifically an electronic unit 17 of the transport refrigeration unit 12. The electronic unit 17 is housed in an electronics enclosure 18 of the transport refrigeration unit 12 and comprises a charger consisting of a power supply and a charge controller, as well as a frequency converter, in particular a bidirectional one. These components heat up during operation of the transport refrigeration unit 12, and their heat can therefore be dissipated from the electronics enclosure 18 via the cooling circuit 16. In the illustrated and thus preferred transport refrigeration unit 12, the cooling circuit 16 runs partly within the electronics enclosure 18 and partly outside of it.Outside the electronics housing 18, a pump is arranged in the cooling circuit 16, although the pump could also be located inside the electronics housing 18. The pump ensures that the coolant circulates in the cooling circuit 16 and flows through the radiator 19 located outside the electronics housing 18. The radiator 19, like the condenser 15 of the refrigeration circuit 14, is cooled by ambient air.

[0033] In the Fig. 3 The radiator 19, the condenser 15, and a blower unit 20 of the transport refrigeration unit 12 are shown in detail. In the illustrated and thus preferred transport refrigeration unit 12, the blower unit 20 is located downstream of the radiator 19 and the condenser 15 in the direction of airflow A of the cooling air K. The radiator 19 and the condenser 15 are therefore arranged on the suction side of the blower unit 20, which draws cooling air K through the radiator 19 and the condenser 15 in the direction of airflow A. Even while the commercial vehicle 1 is in motion, the radiator 19 and the condenser 15 can still be supplied with cooling air K through cooling air inlets 21 in the housing 13 of the transport refrigeration unit 12 in the direction of airflow A, provided the blower unit 20 is switched off.The illustrated and thus preferred fan unit 20 will, however, assist the airflow to the cooler 19 and the condenser 15 as needed, in order to dissipate more heat via the cooler 19 and the condenser 15 to the cooling air K. The illustrated fan unit 20 comprises two axial fans 22 positioned side by side behind the condenser 15. However, a different number and type of fans could also be provided, although axial fans are generally considered particularly preferred.

[0034] The cooler 19 and the condenser 15 each comprise a supply channel 23, 24 and a discharge channel 25, 26, which are connected to each other via a plurality of parallel pipes 27, 28. In the supply channel 23, 24, refrigerant and coolant are supplied separately and distributed via manifolds 35, 36 to the corresponding plurality of pipes 27, 28. The refrigerant and coolant then flow separately through the respective pipes 27, 28, where they are cooled by cooling air K in an oncoming direction A. The heat released is absorbed and carried away by the cooling air K. After cooling, the refrigerant and coolant are collected separately in the respective manifolds 37, 38 and discharged via discharge channels 25, 26. The refrigerant and coolant then continue to flow in the direction of flow through the refrigeration circuit 14 and the cooling circuit 16.

[0035] In the illustrated and thus preferred transport refrigeration machine 12, the individual tubes 27, 28 of the cooler 19 and the condenser 15 are arranged parallel to each other, i.e., within the cooler 19 as well as within the condenser 15. The respective tubes 27, 28 thus form a plane of the cooler 19 and a plane of the condenser 15, wherein the plane of the cooler 19 and the plane of the condenser 15 are arranged parallel to each other in the illustrated and thus preferred transport refrigeration machine 12.

[0036] Viewed in the direction of airflow A of the cooling air K, the cooler 19 is positioned upstream of the condenser 15. Furthermore, the cooler 19 covers the condenser 15 in the direction of airflow A without projecting above, below, or laterally beyond the condenser 15. This is preferred, but not essential. However, the illustrated condenser 15 is taller than the cooler 19, so that in the illustrated and thus preferred transport refrigeration unit 12, the condenser 15 projects transversely to the direction of airflow A and downwards beyond the cooler 19. The width of the cooler 19, however, corresponds at least substantially to the width of the condenser 15 in this case.

[0037] In the Fig. 4 A schematic flow diagram of the commercial vehicle 1 and the transport refrigeration unit 12 is shown. In the middle of the Fig. 4 An electronics housing 18 is shown with an electronics unit 17 comprising a charger 29 and a frequency converter 30. In principle, further components or other assemblies may be provided in the electronics housing 18, which may also be part of the electronics unit 17. The charger 29 and the frequency converter 30 are connected to a battery 31 located outside the electronics housing 18, specifically below the box body 5, on the commercial vehicle 1. The frequency converter 30 is also connected to a generator 32, which is coupled to an axle 4 of the commercial vehicle 1. Electricity can be generated via the axle 4 and the generator 32 while the commercial vehicle 1 is in motion, which can be used to drive the transport refrigeration unit 12.For this purpose, an alternating current with a constant frequency is first generated by the frequency converter 30, since the frequency of the current generated by the generator 32 depends on the rotational speed of the axis 4 or the generator 32. When the commercial vehicle 1 is stationary, the transport refrigeration unit 12 can be connected to an external power supply via a three-phase socket 33 to provide it with voltage. The three-phase socket 33 is connected to the charger 29, which can be used to charge the battery 31 of the commercial vehicle 1. In addition, the current generated by the generator 32 can be converted into direct current via the frequency converter 30 to charge the battery 31. The generator 32 and the three-phase socket 33, like the battery 31, are located outside the electronics housing 18. The refrigeration circuit 14 is also located outside the electronics housing 18.

[0038] The electronics housing 18 incorporates a portion of the cooling circuit 16, which is thermally coupled to the frequency converter 30 and the charger 29 to extract heat from these components. The coolant, heated in this way, then flows into the cooler 19 located outside the electronics housing 18, where heat is transferred to the cooling air K before the cooled coolant is pumped back into the electronics housing 18 by a pump 34. Despite its rather separate representation in the Fig. 4 Preferably, the electronic housing 18 is also part of the transport refrigeration unit 12. The cooling circuit 16 is therefore partly located inside the electronic housing 18 and partly located outside the electronic housing 18. Reference symbol list

[0039] 1Commercial vehicle 2Chassis 3Chassis 4Axles 5Trunk body 6Front wall 7Roof 8Rear wall door 9Rear wall 10Side wall 11Load space 12Transport refrigeration unit 13Housing 14Refrigeration circuit 15Condenser 16Refrigeration circuit 17Electronic unit 18Electronic housing 19Cooler 20Blower unit 21Cooling air inlets 22Axial fan 23,24Supply duct 25,26Exhaust duct 27,28Tubes 29Charger 30Frequency converter 31Battery 32Generator 33Three-phase socket 34Pump 35,36Collector pipe 37,38Collector pipe ADirection of flow KCooling air ZVacuum machine

Claims

1. Transport refrigeration unit (12) for cooling a box body (5) of a utility vehicle (1), in particular a truck, a trailer or a semi-trailer, with a refrigeration circuit (14) for circulating a refrigerant, with an electronics unit (17) for operating the refrigeration circuit (14) and with a cooling circuit (16) for cooling the electronics unit (17), wherein the refrigeration circuit (14) comprises an evaporator for evaporating the refrigerant, a compressor for compressing the refrigerant evaporated in the evaporator, a condenser (15) for condensing the refrigerant compressed in the compressor and an expansion valve for expanding the refrigerant condensed in the condenser (15), wherein the cooling circuit (16) comprises a coolant, a pump (34) for circulating the coolant in the cooling circuit (16) and a cooler (19) for cooling the coolant and wherein the condenser (15) and the cooler (19) are arranged for flow of cooling air (K) in a flow direction (A), characterized in that the cooler (19), viewed in the flow direction of the cooling air (K), is provided at least in sections in front of at least one section of the condenser (15).

2. Transport refrigeration unit according to claim 1, characterized in that the electronics unit (17) comprises at least one charger (29) and / or one frequency inverter (30).

3. Transport refrigeration unit according to claim 2, characterized in that the charger (29) has a charge controller and a power supply unit and / or that the frequency inverter (30) is a bidirectional frequency inverter (30).

4. Transport refrigeration unit according to one of claims 1 to 3, characterized in that the cooler (19) and the condenser (15) are provided on the suction side of at least one blower, axial fan (22), for drawing in cooling air (K) respectively at least partially through the cooler (19) and the condenser (15) .

5. Transport refrigeration unit according to one of claims 1 to 4, characterized in that the cooler (19) and / or the condenser (15) is formed at least substantially from mutually connected, parallel and mutually spaced tubes (27,28) and that, preferably, the parallel tubes (27,28) of the cooler (19) and / or of the condenser (15) are arranged in a plurality of planes arranged one behind the other in the flow direction (A) of the cooling air (K).

6. Transport refrigeration unit according to claim 5, characterized in that the planes of the cooler (19) and of the condenser (15) formed by the parallel tubes (27,28) are arranged parallel to one another.

7. Transport refrigeration unit according to one of claims 1 to 6, characterized in that the cooler (19) and the condenser (15), viewed in the flow direction (A), are provided so as to at least substantially overlap and / or the condenser (15) is arranged only in sections behind the cooler (19) in the flow direction (A).

8. Transport refrigeration unit according to one of claims 1 to 7, characterized in that the cooler (19) and the condenser (15) have at least substantially the same width and / or that the cooler (19) and the condenser (15) have a different height.

9. Transport refrigeration unit according to one of claims 1 to 8, characterized in that the coolant of the cooling circuit (16) is at least substantially water and / or that the refrigerant of the refrigeration circuit (14) is a synthetic refrigerant.

10. Utility vehicle (1), in particular truck, trailer or semi-trailer, with a box body (5) and a transport refrigeration unit (12) provided on a front wall (6) of the box body (5) for cooling at least one cargo space (11) provided in the box body (5), characterized in that the transport refrigeration unit (12) is configured according to one of claims 1 to 9.

11. Utility vehicle according to claim 10, characterized in that a battery (31) for supplying power to the transport refrigeration unit (12) and / or for storing electrical energy is provided below the box body (5).

12. Utility vehicle according to claim 10 or 11, characterized in that a three-phase socket (33) for operating the transport refrigeration unit (12) and / or for storing electrical energy in the battery (31) is provided.

13. Utility vehicle according to one of claims 10 to 12, characterized in that an axle (4) of the utility vehicle (1) coupled to a generator (32) is provided for generating electrical current during travel of the utility vehicle (1) and that, preferably, the frequency inverter (30) is provided for converting the generated alternating voltage of the generator (32) assigned to the axle (4) into an alternating voltage with constant frequency and / or into a direct voltage.

14. Utility vehicle according to one of claims 10 to 13, characterized in that the voltage between the battery (31), the charger (29) and / or the frequency inverter (30) is between 500 V and 900 V, preferably between 600 V and 800 V, in particular between 650 V and 750 V.