TRANSPORT REFRIGERATION SYSTEM

Abstract

A transport refrigeration system includes a transportation refrigeration unit and a generator (13) coupled to a wheel axle (7A) of the transport refrigeration system via a coupling (11). The generator (13) is configured to be driven to generate electricity by rotation of the wheel axle (7A) and to supply that electricity to the transportation refrigeration unit. The coupling (11) that couples the generator and the wheel axle is a magnetic coupling (11).

Claims

1. A transport refrigeration system (1) comprising: a transportation refrigeration unit; and a generator (13) coupled to a wheel axle (7A) of the transport refrigeration system via a coupling (11, 21), wherein the generator is configured to be driven to generate electricity by rotation of the wheel axle and to supply that electricity to the transportation refrigeration unit; wherein the coupling is a magnetic coupling.

2. A transportation refrigeration system according to claim 1, comprising an electrical energy storage device connected to the generator and to the transportation refrigeration unit, the electrical energy storage device being configured to receive and store electrical energy from the generator and to provide electrical power to the transportation refrigeration unit.

3. A transportation refrigeration system according to claim 1, comprising a gearbox (9) coupled between the wheel axle and the generator.

4. A transportation refrigeration system according to claim 3, wherein the gearbox is provided on the generator side of the magnetic coupling.

5. A transportation refrigeration system according to claim 1, wherein the magnetic coupling is an axial magnetic coupling (11).

6. A transportation refrigeration system according to claim 1, wherein the magnetic coupling is a radial magnetic coupling (21).

7. A transportation refrigeration system according to claim 1, wherein the magnetic coupling is a synchronous magnetic coupling (11).

8. A transportation refrigeration system according to claim 1, wherein the magnetic coupling is an asynchronous magnetic coupling.

9. A transportation refrigeration system according to claim 1, wherein the generator side of the magnetic coupling is situated in a housing (12) and/or the wheel axle side of the magnetic coupling is situated in a housing (10).

10. A transportation refrigeration system according to claim 1, wherein the gap between the two sides of the magnetic coupling is adjustable.

11. A transport refrigeration system according to claim 1, comprising a barrier (10, 11) situated in the gap between the two sides of the magnetic coupling.

12. A transportation refrigeration system according to claim 1, wherein the magnetic coupling is configured to transmit a torque in the range of 35 Nm - 400 Nm.

13. A cold chain distribution system comprising at least one transport refrigeration system (1) in accordance with claim 1.

14. A method of assembling a transportation refrigeration system (1), the method comprising: providing a transportation refrigeration unit; coupling, via a coupling (11), a generator (13) to a wheel axle (7A) of the transport refrigeration system such that the generator is configured to be driven to generate electricity by rotation of the wheel axle; and connecting the generator to the transportation refrigeration unit such that the generator is configured to supply electricity to the transportation refrigeration unit; wherein the coupling is a magnetic coupling.

15. A method of assembling a transportation refrigeration system of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Certain preferred embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0050] FIG. 1 shows a transportation refrigeration system;

[0051] FIG. 2 shows components of a prior art transportation refrigeration system;

[0052] FIG. 3 shows a gearbox, an axial magnetic coupling and generator of a transportation refrigeration system;

[0053] FIG. 4 shows an enlarged view of the axial magnetic coupling of FIG. 3;

[0054] FIG. 5 shows one side of the axial magnetic coupling of FIG. 3;

[0055] FIG. 6 shows a modified version of the gearbox, axial magnetic coupling and generator of FIG. 3;

[0056] FIG. 7 shows a gearbox, a radial magnetic coupling and generator of a transportation refrigeration system;

[0057] FIG. 8 shows an enlarged view of the radial magnetic coupling of FIG. 7;

[0058] FIG. 9 shows a modified version of the gearbox, radial magnetic coupling and generator of FIG. 7;

[0059] FIG. 10 is a graphical representation of the torque performance of a synchronous magnetic coupling; and

[0060] FIG. 11 is a graphical representation of the torque performance of an asynchronous magnetic coupling.

DETAILED DESCRIPTION OF THE INVENTION

[0061] FIG. 1 shows a transportation refrigeration system 1 in the form of a refrigerated trailer 1. The refrigerated trailer 1 is attached to a tractor unit 3 and together they form a heavy goods vehicle (HGV). The trailer 1 comprises a transportation refrigeration unit (not shown) in operative association with a cargo space defined within the trailer 1 and for maintaining a controlled temperature environment within the cargo space of the trailer 1.

[0062] The trailer 1 comprises a plurality of wheels 5, each connected to a respective wheel axle 7, 7A. As described in more detail below with reference to FIGS. 3 to 9, a generator via a gearbox is coupled to the wheel axle 7A of the trailer 1. The generator is magnetically coupled to the wheel axle 7A and generates electricity in response to the rotation of the wheel axle 7A. This electricity is then supplied to the transportation refrigeration unit of the trailer 1 to power its components.

[0063] FIG. 3 shows a gearbox 9 rotationally coupled to the wheel axle 7A. In FIG. 3, the wheel axle 7A has been omitted for reasons of clarity; however connection 9A can be seen, which is where the wheel axle 7A rotationally couples to the gearbox 9.

[0064] On an opposed side, the gearbox 9 is also rotationally coupled to a generator 13. As such, the rotational output of the gearbox 9, which is created as a result of rotation of the wheel axle 7A which in turn is created by rotation of as the wheels 5 of the transport refrigeration unit, drives the generator 13 into rotation to thereby generate electricity. This electricity is then suppled to the transportation refrigeration unit of the trailer 1 to provide power thereto.

[0065] The gearbox 9 is coupled to the generator 13 via a magnetic coupling 11. More detailed views of the magnetic coupling 11 can be seen FIGS. 4 and 5.

[0066] As shown in FIGS. 3 and 4, the magnetic coupling 11 is an axial magnetic coupling 11 comprising two parallel and opposed rotor plates 15 separated by an air gap 17. The rotor plates 15 are formed from iron and each rotor plate 15 has, attached thereto so as to face the opposed rotor plate 15, a plurality of axially magnetised permanent magnets 19 glued thereto.

[0067] The arrangement of the permanent magnets 19 on the face of each of the rotor plates 15 can be seen in more detail in FIG. 5. As shown, the axially magnetised permanent magnets 19 on each plate 15 are arranged on each order to form a north-south alternating polarity on the face of the rotor plate 15. This is achieved by alternating with north polarity permanent magnets 19A and south polarity permanent magnets 19B about the face of the rotor plate.

[0068] The permanent magnets 19 on each of the plates 15 are arranged identically such that each north polarity magnet 19A on one of the rotor plates 15 aligns with a corresponding north polarity magnet 19A on the other of the rotor plates 15. Similarly, each south polarity magnet 19B aligns with a corresponding south polarity magnet 19B on the other of the rotor plates 15. In this way, the magnetic coupling 11 is made synchronous.

[0069] With such a coupling 11, as the rotational output of the wheel axle 7A and thereby the gearbox 9 drives the rotor plate 15 to which the gearbox 9 is attached into rotation, the other of the rotor plates 15 is itself driven into rotation, which in turn drives the generator 13 into rotation to thereby create electricity. This electricity is then supplied to the transport refrigeration unity of the trailer 1 to provide power thereto.

[0070] The rotation in the rotor plate 15 attached to the generator 13 occurs due to a torque created by the misalignment in magnetic fields of each the plurality of magnets 19 on each rotor 15 as the rotor plate 15 attached to the gearbox 15 is rotated.

[0071] Since the coupling 11 is synchronous, the side of the coupling 11 (i.e. rotor plate 15) attached to the generator 13 is driven to rotate at the same speed as the side of the coupling 11 (i. e. the rotor plate 15) attached to the gearbox 9.

[0072] The synchronous coupling 11 only permits the transmission of a maximum rotational speed and torque between each of the plates 15 before the coupling becomes decoupled. This is represented in FIG. 10.

[0073] FIG. 10 is a graphical representation of the torque performance of the synchronous magnetic coupling 11, whereby the y-axis represents the torque of the rotor plate 15 attached to the generator 13 and the x-axis represents the torque of the rotor plate 15 attached to the gearbox 9.

[0074] As shown in the portion 101 of the plot, initially as the speed and thereby the torque of the rotor plate 15 attached to the gearbox 9 increases the speed/torque of the rotor plate 15 attached to the generator 13 correspondingly increases. This trend follows, until a maximum torque 102. At this point, the misalignment (i.e. the angle between the magnetic fields) between the pluralities of magnets 19 becomes too large such that the two sides (i.e. the two rotor plates 15) of the coupling 11 decouple and the rotor plate 15 attached to the gearbox 9 no longer drives rotation of the rotor plate attached to the generator. The torque of the rotor plate 15 attached to the generator 13 thus drops to zero as shown in portion 103 despite the rotor plate 15 attached to the gearbox 9 still outputting a torque.

[0075] To recouple the coupling 11 after such a decoupling, resynchronization has to be carried out when both plates 15 have stopped rotating because the system requires a gradual start.

[0076] The concept of a decoupling at a maximum torque provided by the synchronous coupling 11 is advantageous since it allows the coupling 11 to avoid risk of overload to either side of the system. The coupling 11 will drop out before an overload (i.e. an excess of torque) can be applied to either side of the system, thereby avoiding damage to the system, improving safety and the like.

[0077] FIG. 11 is a graphical representation of the torque performance of an asynchronous magnetic coupling. In such a coupling, the side of the coupling being driven into rotation does not necessarily rotate at the same speed as the side of the coupling driving rotation. In FIG. 11, again the y-axis represents the torque of the side of a coupling being driven into rotation and the x-axis represents the torque of the side of the coupling driving rotation.

[0078] Similar to the synchronous coupling as discussed above, and in portion 111, initially as the speed and thereby the torque of the driving part of the coupling increases the speed/torque of the driven part of the coupling correspondingly increases. This trend follows, until a maximum torque 112 is reached. Beyond this point, the coupling does not decouple as is the case for the synchronous coupling 11 discussed above. Instead the driven part of the coupling begins to slip relative to the driving part of the coupling. This is shown in portion 113, where it is demonstrated that irrespective of the increase in torque of the driving part of the system the driven part of the system remains at the same torque and speed. The slip that occurs cause the creation of heat due to the Eddy current effect.

[0079] Whilst, as is the case for the synchronous coupling 11, the asynchronous coupling does not decouple as a maximum torque is reached, a maximum torque is still set by the asynchronous coupling. As such, overload protection is still provided for by the asynchronous coupling, which in turn provides improved safety and reduced likelihood of damage.

[0080] FIG. 6 shows a modified version of the arrangement shown in FIG. 3. The arrangement of FIG. 6 is almost entirely identical to that of FIG. 3, except that housings 10 and 12 are provided on the gearbox 9 and the generator 13 respectively to house respective sides of the magnetic coupling 11 therein.

[0081] The housings 10, 12 prevent the magnets 19 and rotor plates 15 from coming into contact with one another whilst still permitting the magnetic coupling therebetween.

[0082] FIG. 7 shows an arrangement similar to that shown in FIG. 3; however in this arrangement the axial magnetic coupling 11 between the gearbox 9 and the generator 13 has been replaced by a radial magnetic coupling 21. A more detailed view of the radial magnetic coupling of FIG. 7 can be seen in FIG. 8.

[0083] The radial coupling 21 comprises a first rotor 25a attached to the gearbox 9 and defining a cavity 26 therein. On the surface of the first rotor 25a defining the cavity 26 are situated a plurality of magnets 29a.

[0084] The radial coupling 21 additionally comprises a second rotor 25b attached to the generator 13. The second rotor 25b is positioned within the cavity 26 of the first rotor 25a. A plurality of magnets 29b are situated on the outer surface of the second rotor 25b, facing the plurality of magnets 29a situated on the interior of the cavity 26 of the first rotor 25a but spaced therefrom.

[0085] As the gearbox 9 is driven into rotation by the wheel axle 7A, the gearbox 9 drives the first rotor 25a and the plurality of magnets 29a situated thereon into rotation. The rotation of the magnets 29a induces a torque on the magnets 29b of the second rotor 25b which thereby drives the second rotor 25b. In turn, the generator 13 is driven into rotation to generate electricity for supply to the transportation refrigeration unit of the trailer 1.

[0086] FIG. 9 shows a modified version of the arrangement shown in FIG. 7. The arrangement of FIG. 9 is almost entirely identical to that of FIG. 7, except that a housing 10 is provided on the gearbox 9 to house the first rotor 25a therein.

[0087] The housing 10 prevents the magnets 29a and 29b and rotors 25a and 25b from coming into contact with one another whilst still permitting a magnetic coupling therebetween.