GB2224108A - Refrigerated vehicle - Google Patents

Abstract

A refrigerated vehicle with two or more compartments 2,4,6 is described. A heat exchanger 8 and associated air circulation means 10 is provided in the forwardmost compartment. A heater is provided in a chamber positioned between two adjacent compartments 4,6, the chamber being connected to the compartments by passages which are controlled by air flow control means e.g. gravity flaps and fans so that air may be passed from one compartment to another either directly or across the heater, or from one compartment across the heater and back to the same compartment. <IMAGE>

Description

IMPROVEMENTS IN AND RELATING TO A TEMPERATURE CONTROL SYSTEM.

This invention relates to the temperature control of a number of enclosed spaces and in particular to the temperature control of the load-carrying compartments of multi-compartment thermally insulated vehicles such as lorries, trailers, semi-trailers, containers and vans.

It is known to control the temperatures in more than one vehicle compartment so that, for example, one compartment can carry frozen foodstuffs and another, goods that require to be kept at ambient temperatures.

One system for achieving this has a refridgeration unit with its heat exchanger located in the compartment which is to be kept at the lowest temperature, normally this is arranged to be the forwardmost compartment so that the unit can be simply connected to the power. The compartments are interconnected by air ducts in the bulkheads fixed or movable, which separate the compartments, fans being provided in the ducts. The temperature in the compartment in which the heat exchanger is located is controlled thermostatically.

The temperature in the other compartments is sensed by thermostatic probes located in the comparment which are operable to control the operation of the fans and ducts between the compartments.

When the temperature sensed by the thermostatic probe in the compartment adjacent the compartment in which the heat exchanger is located is too high, the probe causes the duct between the first and second compartments to open and activates the fan located therein to cause cold air to be transferred into the second compartment until the temperature is sufficiently low. The temperatue in a third compartment can similarly be lowered by transferring cold air from the first or second compartment.

The refridgeration unit normally extracts heat to lower the temperature of the air in the first compartment but it is often arranged to be also capable of heating the air to raise the temperature of the first compartment. Indeed, the unit may be operable to alternately heat and cool to keep the temperature in the compartment at the required level.

However, this system has the disadvantage that the first compartment may be heated or cooled but if it is being cooled then the other compartments, by the transfer of relatively cold air, can also only be cooled. Since for practical reasons the compartment in which the heat exchanger is located is often kept at the lowest temperatue, no heating facility is available in the other compartments. Tile transfer of warm air to other compartments would only be possible if the first compartment was kept at a temperature well above ambient which is unlikely to occur in practice.

One solution to this problem which has been suggested is to locate the refridgeration unit in a separate chamber which is connected to a discharge duct and a return duct, the ducts in turn being selectively connected to each of the compartments whose temperaure is to be controlled. When it is desired to cool (or heat) one of the compartments, the connections between it and the ducts are opened and air from the compartment passes along the return duct, across the heat exchanger where it is cooled (or heated) and back to the compartment via the discharge duct. This system permits individual temperature control of the compartments but has the disadvantage that the vehicle must be provided with the chamber for mounting the refridgeration unit and the system of ducting which increases design difficulty and adds to the cost of the vehicle.

A second solution is to provide separate heaters in the second and subsequent compartments, each heater being connected to the associated compartment by a passage controlled by flaps. When the flaps are open, a fan associated with the heater causes air from the compartment to be sucked out, passed through the heater and returned to the compartment. Thus, the temperature in each compartment can be lowered by the transfer of air from a cooled compartment or raised by operating the flaps, fan and heater associated with the compartment.

The provision of a separate heating arrangement for each compartment adds to the expense of the vehicle and increases the complexity of the design of the bulkheads.

In accordance with the present invention a refridgerated vehicle comprises at least two compartments, a heat exchanger and an associated air circulation means to heat or cool the compartment means for transferring air from one compartment to an adjacent compartment according to the temperature of the compartments, a heater positioned in a chamber between two adjacent compartments, means for activating the heater when it is desired to raise the temperature in either of the adjacent compartments, the chamber being connected to the compartments by passages and associated flow control means, the arrangement being such that air may be passed from and to the same compartment over the heater when the heater is energised.

The advantage of this is that a single heater is employed to raise the temperature of two of the compartments. The arrangement therefore reduces the number of heaters required.

Preferably, the passages and associated air flow control means also act as the means for transferring the air between the two compartments between which the heater is provided. Therefore a single air flow control means not only transfers air between two adjacent compartments, but also co-operates with the heater to raise the temperature of either of the compartments.

Thus each air flow control means can act not only to cool the compartments it interconnects by transfer of air from the cooler of the two to the warmer of the two, but also to heat either compartment in co-operation with the heater. Thus the air flow control means serve a dual purpose with consequently reduced equipment costs and increased design simplicity.

Suitably the air flow control means comprises a plurality of flaps, the operation of each of which can preferably be separately controlled, and at least one fan. Two flaps and a fan are arranged above and below the heater. One of each pair of flaps is positioned between the chamber containing the fans and the heater and one of the compartments. The flaps are preferably gravity flaps and the fans are bidirectional.

The heat exchanger may be located in the forwardmost compartment of the refridgerated vehicle and the air flow control means in the bulkheads between the compartments. The air flow control means serve to pass cold air from the forwardmost compartment to the other compartments . In a vehicle with three compartments the heater is located between the middle and rearward most compartments and co-operates with the associated air control means to raise the temperature of these compartments as required.

The invention will now be further described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic view of the temperature control system of the invention; Figure 2 is a sectionaL view through part of the temperture control system of Figure 1 in a first mode of operation; Figure 3 is a view along II - III of the system of Figure 2; Figure 4 is a similar view to Figure 2 showing a second mode of operation and Figure 5 is a similar view to Figure 2 showing a third mode of operation.

Figure 1 shows three enclosed spaces 2, 4 and 6 whose temperature is to be controlled. The system for controlling the temperatures of these spaces comprises a heat exchanger 8 which has an associated fan 10 located in one of the chambers 2. The chamber 2 containing the heat exchanger is connected to the adjacent chamber 4 by air flow control means 12 . This comprises a passage between the two chambers controlled either by flaps or as shown by two valves 14a and 14b, a fan 16. Generally heat exchanger 8 which is suitably the evaporator of a mechanically driven refridgeration unit cools the temperature of the air in chamber 2 by extracting heat from the chamber. When it is desired to cool chamber 4 a temperature probe (not shown) in that chamber acts to open the valves 14a and 14b and activates the fan 16 to cause cool air to be transferred to chamber 4 .When the desired temperature is reached in that chamber the probe causes the valves to close and the fan to be deactivated.

Chamber 6 also contains a temperature probe (not shown). The probes in both chambers 4 and 6 are connected to the part of the system generally shown by reference numeral 18 and shown in greater detail in Figures 2 to 5. This comprises a casing 19 connected to the chambers 4 and 6 by four sets of gravity fans 20, 22, 24 and 26 and containing two biderectional fans 28 and 30 and a heater 32.

When the temperature in chamber 6 is to be lowered by transfer of cold air from chamber 4, the mode of operation is shown in Figure 2. The temperature probe in chamber 6 causes the flaps 22 and 24 to open and activates the fans 28 and 30 in the same direction, as shown by arrow 34. Air flows from chamber 4 through flap 24 into the casing 19 and into chamber 6 through flap 22 (see arrows 36). The flaps 14a and 14b may also be opened and fan 16 activated by the temperature probe in chamber 4 so that air also flows from the chamber 2 to chamber 6.

When the temperature in the second compartment is to be raised, the mode of operation is as shown in Figure 4. The temperature probe in that chamber opens flaps 20 and 24, activates the fans 28 and 30 in opposite directions (see arrows 38) and activates the heater 32. Air flows into the casing 19 through flap 24, over the heater 32 and back to chamber 4 via flap 20 (see arrows 40). When the desired temperature is reached the fans and heater are deactivated and the flaps closed.

To heat chamber 6, a third mode of operation is employed as shown in Figure 5. The temperature probe opens flaps 22 and 26 activates the heater 32 and activates fans 28 and 30 in opposite directions to each other but in the reverse sense to that in the mode shown in Figure 4 (arrows 42). Air flows into the casing 19 through flap 26 across the heater and back to chamber 6 by way of flap 22 (see arrows 44). The system is shut down as soon as the required temperature is reached.

A fourth mode of operation is possible where air is transferred from chamber 6 to chamber 4 and is the reverse of that shown in Figure 2 but it is unlikely to be required.

The system described above is particularly suitable for controlling the temperature of the compartments of a multicompartment refridgerated vehicle. The valves 14a and 14b and fan 16 or the system 18 are provided in the bulkheads which form the compartments. If the vehicle has three compartments then an arrangement as shown in Figure 1 is preferably employed. Compartment 2 is used for the goods which require the lowest temperatures and cooling of the other compartments 4 and 6 is effected by operation of the valves 14a and 14b and fan 16 and/or the system 18 in the mode shown in Figure 2. Compartment 2 is heated if required bs heat exchanger 8 and compartments 4 and 6 are heated by heater 32 with system 18 operating in the modes shown in Figures 4 and 5 respectively.

If a vehicle has a larger number of compartments a system 18 is provided between alternate pairs of compartments and an air flow control means 12 is provided between the other compartments. For example with five compartments, a system 18 is provided between the second and third and the fourth and fifth compartments considered from the front of the vehicle and an air flow control means 12 connects the first and second and the third and fourth compartments..

When a vehicle has only two compartments then a system 18 is provided between them. The two compartments are cooled by means of the heat exchanger and heated by the heater 32 in the system 18. Therefore the heat exchanger is only required to cool which has the advantage that the need for time delay between heating and cooling (or vice-versa) to allow the heat exchanger to reach the required temperature is avoided.

The temperature control system described above allows a single heater to be employed to heat two compartments rather than the two heaters required in known systems and permits passage of air between the compartments. It therefore allows both heating and cooling of the compartments in an economical and practical design.

Claims (12)

CLAIMS:

1. A refrigerated vehicle comprising at least two compartments, a heat exchanger and an associated air circulation means to heat or cool one of the compartments, means for transferring air from one compartment to an adjacent compartment according to the temperature of the compartments, a heater positioned in a chamber between two adjacent compartments, means for activating the heater when it is desired to raise the temperature in either of the adjacent compartments, the chamber being connected to the compartments by passages and associated flow control means, the arrangement being such that air may be passed from and to the same compartment over the heater.

2. A refrigerated vehicle as claimed in Claim 1 in which the passages and associated air flow control means also act as the means for transferring the air between the two compartments between which the heater is provided.

3. A refrigerated vehicle as claimed in either Claim 1 or Claim 2 wherein the air flow control means comprises a plurality of flaps, each of which is operable to permit passage of air through one of the passages, and at least one fan.

4. A refrigerated vehicle as claimed in Claim 3 wherein the operation of each of the flaps can be individually controlled.

5. A refrigerated vehicle as claimed in either Claim 3 or Claim 4 wherein two flaps and a fan are provided above and below the heater.

6. A refrigerated vehicle as claimed in Claim 5 wherein one of each pair of flaps controls the passage of air between the chamber and one of the compartments while the other of each pair of flaps controls the passage of air between the chamber and the adjacent compartment.

7. A refrigerated vehicle as claimed in any one of Claims 3 to 6 wherein the flaps are gravity flaps.

8. A refrigerated vehicle as claimed in any one of Claims 3 to 7 wherein the fans are bidirectional.

9. A refrigerated vehicle as claimed in any preceding Claim wherein the heat exchanger and associated air circulation means are provided in the forwardmost compartment.

10. A refrigerated vehicle as claimed in any preceding Claim wherein the means for transferring air from one compartment to an adjacent compartment according to the temperature of the compartments is provided in the bulkhead which divides the vehicle into the at least two compartments.

11. A refrigerated vehicle as claimed in any preceding Claim wherein the chamber is provided in the bulkhead(s) which divides the refrigerated vehicle into the compartments.

12. A refrigerated vehicle as hereinbefore described with reference to the accompanying drawings.