Patent Description:
Fruits, vegetables and other perishable items, including meat, poultry and fish, fresh or frozen, are commonly transported in a transport refrigeration system (transport refrigeration system). The transport refrigeration system may include a refrigerated container, for example a cargo box of a truck in the form of a trailer, or in an intermodal container. Accordingly, it is customary to provide a transport refrigeration system in operative association with the refrigerated container for cooling the atmosphere within the refrigerated container. The transport refrigeration system includes a refrigerant vapor compression system, also referred to as a transport refrigeration unit (TRU), and an onboard power unit. The refrigerant vapor compression system typically includes a compressor, a condenser, an expansion device and an evaporator serially connected by refrigerant lines in a closed refrigerant circuit in accord with known refrigerant vapor compression cycles. The power unit includes an engine, typically diesel powered. It is desirable to detect hazards, such as flammable gasses, within compartments of a refrigerated container.

<CIT> discloses a refrigeration system located within a container and at least one sensor located within the container configured to detect the presence of refrigerant.

<CIT> and <CIT> each disclose examples of refrigeration systems for refrigerating transport compartments.

Viewed from a first aspect, the invention provides a transport refrigeration system as defined by claim <NUM>.

Optionally, the plurality of sensors receive power from and communicate with the auxiliary controller.

Optionally, the system includes a primary display that is onboard the transport refrigeration system, and wherein the primary controller is configured to provide the alert on the primary display when the primary controller receives the first communication.

Optionally, the primary controller is configured to communicate over a wireless network, and the primary controller is configured to communicate the alert over the wireless network to one or more of a mobile device, a service station and a central server when one of the plurality of sensors detects refrigerant.

According to a second aspect of the invention a method of monitoring for hazards in a transport refrigeration system is provided as defined by claim <NUM>.

Optionally, the method includes the auxiliary controller providing power to and communicating with the plurality of sensors.

Optionally, the method includes outputting by the primary controller, responsive to receiving the first communication, the alert on a primary display for the transport refrigeration system.

Optionally, the method includes transmitting by the primary controller, responsive to receiving the first communication, the alert over a wireless network to one or more of a mobile device, a service station and a central server.

Referring initially to <FIG> and <FIG>, there are depicted exemplary embodiments of transport refrigeration systems (transport refrigeration system) <NUM> for controlling the temperature of the atmosphere within the refrigerated container <NUM> of the transport refrigeration system <NUM>, which may be hauled by a truck <NUM> (<FIG>). The refrigerated container <NUM> may be for example a trailer (<FIG>), intermodal container or similar cargo transportation unit hauled by a tractor <NUM> (<FIG>) or a rail car. The transport refrigeration system <NUM> includes a transport refrigeration unit (TRU) <NUM> including a compressor <NUM>, a (refrigerant) condenser heat exchanger <NUM>, an expansion device <NUM>, a (refrigerant) evaporator heat exchanger <NUM> and a suction modulation valve <NUM> connected in a closed loop refrigeration circuit including refrigerant lines respectively <NUM>, <NUM> and <NUM> and arranged in a conventional refrigeration cycle.

The transport refrigeration system <NUM> further includes, in addition to the TRU <NUM>, an electronic primary controller (primary controller) <NUM>, a (diesel) engine <NUM> and an engine controller (EC) <NUM>. The transport refrigeration system <NUM> is mounted as in conventional practice to an exterior wall of the truck <NUM> (<FIG>) with the compressor <NUM> and the condenser heat exchanger <NUM> with its associated condenser fan(s) (not illustrated) and engine <NUM> disposed externally of the refrigerated container. The EC <NUM>, also known as powertrain control module (PCM), engine control unit (ECU), or auto engine computer (automotive engine control module) may be considered the brain of the engine <NUM>. A EC <NUM> when malfunctioning may produce an activated check engine light, an engine misfiring, an engine stalling, a decreased engine performance, and/or a non-starting engine.

When the transport refrigeration system <NUM> is operating in a cooling mode, low temperature, low pressure refrigerant vapor is compressed by the compressor <NUM> to a high pressure, high temperature refrigerant vapor and passed from the discharge outlet of the compressor <NUM> into refrigerant line <NUM>. The refrigerant circulates through the refrigerant circuit via refrigerant line <NUM> to and through the heat exchange tube coil or tube bank of the condenser heat exchanger <NUM>, wherein the refrigerant vapor condenses to a liquid, thence through the receiver <NUM>, which provides storage for excess liquid refrigerant, and thence through the subcooler coil <NUM> of the condenser. The subcooled liquid refrigerant then passes through refrigerant line <NUM> through a first refrigerant pass of the refrigerant-to-refrigerant heat exchanger <NUM>, and thence traverses the expansion device <NUM> before passing through the evaporator heat exchanger <NUM>. In traversing the expansion device <NUM>, which may be an electronic expansion valve (EXV) as depicted in <FIG> or a mechanical thermostatic expansion valve (TXV) as depicted in <FIG>, the liquid refrigerant is expanded to a lower temperature and lower pressure prior to passing to the evaporator heat exchanger <NUM>.

In flowing through the heat exchange tube coil or tube bank of the evaporator heat exchanger <NUM>, the refrigerant evaporates, and is typically superheated, as it passes in heat exchange relationship return air drawn from the refrigerated container <NUM> passing through the airside pass of the evaporator heat exchanger <NUM>. The refrigerant vapor thence passes through the refrigerant line <NUM>, the refrigerant vapor traverses a second refrigerant pass of the refrigerant-to-refrigerant heat exchanger <NUM> in heat exchange relationship with the liquid refrigerant passing through the first refrigerant pass thereof. Before entering the suction inlet of the compressor <NUM>, the refrigerant vapor passes through the suction modulation valve <NUM> disposed in refrigerant line <NUM> downstream with respect to refrigerant flow of the refrigerant-to-refrigerant heat exchanger <NUM> and upstream with respect to refrigerant flow of the compressor <NUM>. By selectively reducing the open flow area through the suction modulation valve <NUM> with the primary controller <NUM> (<FIG>) a flow of refrigerant vapor supplied to the compressor <NUM> is selectively restricted, thereby reducing the capacity output of the transport refrigeration system <NUM> and in turn reducing the power demand imposed on the engine <NUM>.

Air drawn from within the refrigerated container <NUM> by the evaporator fan(s) (not shown) associated with the evaporator heat exchanger <NUM>, is passed over the external heat transfer surface of the heat exchange tube coil or tube bank of the evaporator heat exchanger <NUM> and circulated back into the interior space of the refrigerated container <NUM>. The air drawn from the refrigerated container <NUM> is referred to as "return air" and the air circulated back into the refrigerated container <NUM> is referred to as "supply air". It is to be understood that the term "air" as used herein includes mixtures of air and other gases, such as for example, but not limited to nitrogen or carbon dioxide, sometimes introduced into a refrigerated container <NUM> for transport of perishable product such as produce.

Although the particular type of evaporator heat exchanger <NUM> used is not limiting of the disclosed embodiments, the evaporator heat exchanger <NUM> may, for example, comprise one or more heat exchange tube coils, as depicted in the drawing, or one or more tube banks formed of a plurality of tubes extending between respective inlet and outlet manifolds. The tubes may be round tubes or flat tubes and may be finned or un-finned.

The compressor <NUM> may comprise a single-stage or multiple-stage compressor such as, for example, a reciprocating compressor as depicted in <FIG> and <FIG>. However, the compressor <NUM> may be a scroll compressor or other type of compressor as the particular type of compressor used is not germane to or limiting of the disclosed embodiments. In <FIG>, the compressor <NUM> comprises a reciprocating compressor having a compressing mechanism, an internal electric compressor motor and an interconnecting drive shaft that are all sealed within a common housing of the compressor <NUM>. The engine <NUM> drives an electric generator <NUM> that generates electrical power for driving the compressor motor, which in turn drives the compression mechanism of the compressor <NUM>. The drive shaft of the engine <NUM> drives the generator shaft. In the embodiment of <FIG>, the compressor <NUM> is a reciprocating compressor having a compressing mechanism with a shaft driven directly by the drive shaft of the engine <NUM>, either through a direct mechanical coupling or through a belt drive <NUM> as illustrated in <FIG>.

Turning to <FIG>, additional features of the transport refrigeration system <NUM> are illustrated. As indicated, the transport refrigeration system <NUM>, including the TRU <NUM>, the primary controller <NUM>, the engine <NUM> and the EC <NUM>, may be disposed the refrigerated container <NUM> of the truck <NUM>, and hauled by the tractor <NUM>. A thermostat <NUM> may be provided in the truck <NUM> for use by the primary controller <NUM> in controlling the EC <NUM> to operate the TRU <NUM>. A primary display <NUM> for the transport refrigeration system <NUM> may be provided to display faults and other information obtained from the EC <NUM>. The primary controller <NUM> may be linked, for example by a wireless network <NUM>, to one or more of a mobile device <NUM>, e.g., a cellular phone for a driver of the truck <NUM>, a central server <NUM> located in a central hub <NUM>, which may be fleet headquarters, and a service station <NUM> that may be in route. With the configuration, the primary controller <NUM> may communicate the faults and other information obtained by the EC <NUM>, and provide other health and status data, temperature and otherwise, as may be required. The primary controller <NUM> may also be equipped to with a global positioning system (GPS) <NUM>, which can be used to obtain relative distances between the truck <NUM>, the central hub <NUM> and the service station <NUM> that may be in-route.

Turning to <FIG>, the transport refrigeration system <NUM> includes a hazard detection system <NUM>, which is a distributed system as disclosed herein. The hazard detection system <NUM> includes an auxiliary controller <NUM>, which may be a microprocessor. In some embodiments the auxiliary controller <NUM> is integral with the primary controller <NUM> (<FIG>). The hazard detection system <NUM> may also encompass controls for activation of external safety systems, such as exhaust fans in case of a refrigerant or other gas leak, extinguishers in case of a fire, and the like. A plurality of sensors <NUM>, including a first sensor 170a and a second sensor 170b, are disposed in a respective plurality of compartmentalized rooms (compartments) <NUM>, including a first compartment 200a and a second compartment 200b, of the refrigerated container <NUM>. In the illustrated embodiment the plurality of sensors <NUM> are gas detectors and the refrigerated container <NUM> is a trailer cargo box. The sensors <NUM> are configured to detect refrigerant leaks within the compartments <NUM> of the refrigerated container <NUM>. Each of the plurality of sensors <NUM> may communicate with and be controlled by the auxiliary controller <NUM>. In the hazard detection system <NUM> each of the plurality of sensors <NUM> may be located proximate one of a respectively plurality of fans <NUM>, including a first fan 175a proximate the first sensor 170a. The plurality of fans <NUM> draw gasses toward the respective one of the plurality of sensors <NUM> to enable detecting a refrigerant leak.

Turning to <FIG>, the hazard detection system <NUM> includes electrical connections <NUM> to integrate the plurality of sensors <NUM>, including the first sensor 170a and the second sensor 170b disposed in the respective plurality of compartments <NUM>, including the first compartment 200a and the second compartment 200b, of the refrigerated container <NUM>. The electrical connections <NUM> are configured to provide power as well as communications between the plurality of sensors <NUM> and the auxiliary controller <NUM>. Optionally, one sensor 170c (not illustrated in <FIG>) of the plurality of sensors <NUM> may be integrated into the auxiliary controller <NUM>. The hazard detection system <NUM> would remain distributed so long as at least one of the first sensor 170a and the second sensor 170b is remotely controlled by the auxiliary controller <NUM>.

The auxiliary controller <NUM> can translate information from the plurality of sensors <NUM> from the plurality of compartments <NUM> and communicate with the primary controller <NUM>. From this, the primary controller <NUM> may output a response <NUM> which may include communicating an alert and/or to engaging in a safety procedure. Such procedure may include venting using the plurality of fans <NUM> and/or to engage a warning system. In one embodiment the primary controller <NUM> may send an alert to one or more of the primary display <NUM>, the mobile device <NUM> of the driver or other designated person, to the central server <NUM> and the service station <NUM> that may be in-route, that a hazard condition is detected and requires attention.

Turning to <FIG>, a method of monitoring for hazards in a transport refrigeration system <NUM> is illustrated. The method includes block <NUM> of monitoring for hazard conditions in a plurality of compartments <NUM> of a refrigerated container <NUM> of the transport refrigeration system <NUM> by the auxiliary controller <NUM> communicating with a plurality of sensors <NUM> respectively distributed in the plurality of compartments <NUM>. Block <NUM> includes determining at the auxiliary controller <NUM> that a hazard condition is detected by one of the plurality of sensors <NUM>. Block <NUM> includes transmitting a first communication, by the auxiliary controller <NUM> to a primary controller <NUM> of the transport refrigeration system <NUM>, indicative of determining at the auxiliary controller <NUM> that a hazard condition is detected. Block <NUM> includes outputting by the primary controller <NUM>, responsive to receiving the first communication, a response including communicating an alert and/or engaging in a safety procedure.

In one embodiment, block <NUM> includes block <NUM> of providing power to and communicating with the plurality of sensors <NUM>. Block <NUM> may also include block <NUM> of drawing gaseous refrigerant toward the plurality of sensors <NUM> with a plurality of fans <NUM> respectively distributed in the plurality of compartments <NUM>.

In one embodiment, block <NUM> includes block <NUM> of outputting by the primary controller <NUM>, responsive to receiving the first communication, the alert on a primary display <NUM> for the transport refrigeration system <NUM> ("screen alert" output type at block <NUM>). Block <NUM> may include block <NUM> of transmitting by the primary controller <NUM>, responsive to receiving the first communication, the alert over the wireless network <NUM> to one or more of the mobile device <NUM>, the service station <NUM> and the central server <NUM> ("wireless alert" output type at block <NUM>). Block <NUM> may include block <NUM> of engaging the safety procedure by the primary controller <NUM>, responsive to receiving the first communication, including drawing air out of the plurality of compartments <NUM> with the respective plurality of fans <NUM> ("safety procedure" output type at block <NUM>).

Claim 1:
A transport refrigeration system (<NUM>), comprising:
a primary controller (<NUM>);
a refrigerated container (<NUM>) with a plurality of compartments (<NUM>); and
a hazard detection system (<NUM>) comprising:
an auxiliary controller (<NUM>);
a plurality of sensors (<NUM>) respectively distributed in the plurality of compartments (<NUM>) of the refrigerated container (<NUM>) of the transport refrigeration system (<NUM>), each of the plurality of sensors (<NUM>) operationally connected to and controlled by the auxiliary controller (<NUM>); and
a plurality of fans (<NUM>) operationally connected to the plurality of sensors (<NUM>) and configured to draw air toward the plurality of sensors (<NUM>), and wherein the plurality of sensors (<NUM>) detect refrigerant,
wherein:
the auxiliary controller (<NUM>) is operatively connected to the primary controller (<NUM>);
the auxiliary controller (<NUM>) is configured to transmit a first communication, to the primary controller (<NUM>) of the transport refrigeration system (<NUM>), indicative of determining at the auxiliary controller (<NUM>) that a hazard condition is detected;
the primary controller (<NUM>) is configured to output a response including communicating an alert and/or engaging in a safety procedure when the primary controller (<NUM>) receives the first communication; and
the primary controller (<NUM>) is configured to engaging the safety procedure by drawing air out of the plurality of compartments (<NUM>) with the plurality of fans (<NUM>) when the primary controller (<NUM>) receives the first communication.