Patent Description:
Typically, cold chain distribution systems are used to transport and distribute cargo, or more specifically perishable goods and environmentally sensitive goods (herein referred to as perishable goods) that may be susceptible to temperature, humidity, and other environmental factors. Perishable goods may include but are not limited to fruits, vegetables, grains, beans, nuts, eggs, dairy, seed, flowers, meat, poultry, fish, ice, and pharmaceuticals. Advantageously, cold chain distribution systems allow perishable goods to be effectively transported and distributed without damage or other undesirable effects.

Refrigerated vehicles and trailers are commonly used to transport perishable goods in a cold chain distribution system.

Conventionally, transport refrigeration systems (such as refrigerated vehicles and refrigerated trailers) include a transportation 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. The transport refrigeration unit is mounted to the vehicles or to the trailer in operative association with a cargo space defined within the vehicles or trailer for maintaining a controlled temperature environment within the cargo space. 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 such as refrigerated vehicles and refrigerated trailers, the compressor, and typically other components of the transportation refrigeration unit, must be powered during transit by an electric motor. In an electrically driven transport refrigeration system, a prime mover of the transport refrigeration system (e.g. a wheel and/or a wheel axle) drives an AC synchronous or AC asynchronous generator that generates AC power. The generated AC power is used to power the electric motor for driving the refrigerant compressor of the transportation refrigeration unit and also powering electric AC fan motors for driving the condenser and evaporator motors and electric heaters associated with the evaporator. <CIT>, <CIT>, <CIT> and <CIT> disclose examples of known transport refrigeration systems.

Safer and more efficient methods of generating electrical power from a prime mover of the transport refrigeration system are envisaged.

According to a first aspect of the present invention, there is provided a transport refrigeration system comprising: a transportation refrigeration unit; an energy storage device configured to provide electrical power to the transportation refrigeration unit; and an electric generation device operably connected through a mechanical interface to at least one of a wheel of the transport refrigeration system and a wheel axle of the transport refrigeration system; wherein the mechanical interface comprises: a first clutch mechanism operable to selectively engage the electric generation device with at least one of the wheel and the wheel axle to generate electrical power to charge the energy storage device; and a second clutch mechanism, wherein the second clutch mechanism is an overrunning clutch configured to disengage the electric generation device from the wheel and/or the wheel axle when a rotational velocity of the electric generation device is greater than a rotational velocity of the wheel and/or wheel axle.

This configuration has advantages over conventional arrangements of electric generation devices as there is provided two distinct mechanisms to control when the electric generation device is engaged with the wheel and/or the wheel axle. The inventors have identified that if an electric generation device is rotatably engaged with a wheel and/or wheel axle of a transport refrigeration system such as a refrigerated vehicle during an emergency stopping manoeuvre, the electric generation device can act to drive the wheel and/or wheel axle if the wheel and/or wheel axle decelerates faster than the electric generation device.

Clutch mechanisms which are externally controlled can include a delay in the control response - for example, the additional reaction time of a human operator and/or the delay for the actuation of controllable elements. However, in an emergency stop of a transport refrigeration system, it is desirable to provide immediate/instantaneous disengagement of the electric generation device from the wheel and/or wheel axle of the transport refrigeration system to prevent these components being inadvertently driven by the electric generation device and reducing the stopping effectiveness of the transport refrigeration system.

In the present invention, the first clutch mechanism can be operated to selectively engage the electric generation device when it is desired to charge the energy storage device. For example, it may be desired to recover rotational energy from the wheel and/or the wheel axle during deceleration of the vehicle (e.g. when braking is applied), and/or during downhill travel of the vehicle, and/or during controlled stopping manoeuvres when the vehicle is brought to a complete rest. However, during an emergency stopping manoeuvre the rotational velocity of the wheel and/or the wheel axle will attempt to decelerate faster than the electric generation device as a result of the rotational inertia of the rotor of the electric generation device. Additionally, generator motoring and other undesirable effects can occur in the electric generation device. As such, during an emergency stopping manoeuvre, the electric generation device can act to drive the wheel and/or the wheel axle, reducing the effectiveness of the braking and putting mechanical stress on the mechanical interface and the electric generation device.

In order to address this issue, the second clutch mechanism provides a second mechanism of control in the form of an overrunning clutch. The overrunning clutch is configured to disengage the electric generation device from the wheel and/or the wheel axle when a rotational velocity of the electric generation device is greater than a rotational velocity of the wheel and/or axle. The overrunning clutch (or freewheel clutch) can advantageously give an immediate mechanical disengagement, with no delay for actuation of controllable elements or other types of control. Accordingly, particularly during an emergency stopping manoeuvre, if the electric generation device is engaged with the wheel and/or the wheel axle and the rotational velocity of the electric generation device becomes greater than the rotational velocity of the wheel and/or the wheel axle, then the overrunning clutch will disengage the electric generation device from the wheel and/or the wheel axle. Transmission of driving force from the electric generation device to the wheel and/or wheel axle is therefore avoided and the system is safer and less likely to break down due to undesired mechanical stresses exerted on the mechanical interface.

The mechanical interface is configured to control the transfer of rotational energy of the wheel and/or the wheel axle to the electric generation device. In other words, when the wheel and/or wheel axle is engaged with the electric generation device through the mechanical interface, rotational motion is transferred from the wheel and/or wheel axle to an input shaft of the electric generation device. When the mechanical interface has disengaged the electric generation device from the wheel and/or the wheel axle, rotational motion is not transferred to the electric generation device.

Accordingly, the mechanical interface may comprise one or more components configured to transfer rotational motion. The one or more components may change the speed, torque or direction of the rotation. The mechanical interface may comprise at least one of a belt system, one or more drive shafts, a gear box and a drive train.

One or more components of the mechanical interface may be externally controllable. For example, the mechanical interface may be controlled to select a different gear ratio to change the torque transmitted from the wheel and/or wheel axle to the electric generation device. Each controllable component of the mechanical interface may be controlled by a separate electronic, pneumatic or hydraulic control system, or a single electronic, pneumatic or hydraulic control system may control all controllable components of the mechanical interface.

The second clutch mechanism may be positioned to directly connect the mechanical interface to the electric generation device.

As such, the remaining components of the mechanical interface are automatically mechanically disconnected from the electric generation device if the rotational velocity of the mechanical interface falls below the rotational velocity of the electric generation device. Thus, if a fault develops in the mechanical interface to slow/stop its rotation, e.g. a gear jamming, the action of the second clutch mechanism will prevent the electric generation device from attempting to drive the mechanical interface and cause inadvertently damage to the components of the mechanical interface.

At least part of the mechanical interface may be integrated within the electric generation device.

The second clutch mechanism may be integrated with the electric generation device. Advantageously the configuration of the electric generation device can be made more compact.

The second clutch mechanism may be directly connected to a drive (input) shaft of the electrical generation device.

The second clutch mechanism may be positioned to directly connect the mechanical interface to at least one of the wheel and the wheel axle.

As such, during an emergency stopping manoeuvre, the wheel and/or the wheel axle is also not inadvertently driven by the rotational inertia of the mechanical interface.

The first clutch mechanism may be integrated with the electric generation device. The first clutch mechanism may be controlled by a controller of the electric generation device. Where the first clutch mechanism is electronically controlled, all of the electrical components of the energy management system can thus be located together and protected from external conditions by a housing or such like.

The overrunning clutch may automatically and/or immediately mechanically disengage the electric generation device from the wheel and/or the wheel axle when a rotational velocity of the electric generation device is greater than a rotational velocity of the wheel and/or axle.

If the response of the overrunning clutch is automatic, this allows the system to respond instantaneously, or at least at timescales that are relevant during an emergency stopping manoeuvre.

The overrunning clutch may be a solely mechanical device. The overrunning clutch may not comprise any controllable components. Thus the response of the device is mechanical and immediate, not comprising any delays from the software or hardware operation of the controllable components.

By using a simple mechanical overrunning clutch the cost of the system can be kept low while still optimising its safety. The mechanical overrunning clutch can also provide clutch mechanism control even in the event of a failure of the first clutch mechanism or a failure of a controller of the transport refrigeration system.

The overrunning clutch may be one of a sprag clutch, a roller ramp clutch, a wrap spring clutch or a wedge ramp clutch.

The electric generation device may be a hub generator operably connected through the mechanical interface to a wheel of the transport refrigeration system.

The electric generation device may be an axle generator operably connected through the mechanical interface to a wheel axle of the transport refrigeration system.

The electric generation device may be a permanent magnet AC generator, reluctance AC generator, asynchronous AC generator, or a synchronous AC generator.

The overrunning clutch may be retrofitted into an existing mechanical interface of a transport refrigeration system.

The first clutch mechanism may comprise one or more controllable components. The first clutch mechanism may be an electric clutch mechanism. The first clutch mechanism may comprise one or more actuators.

By providing a clutch mechanism that can be externally controlled (by an operator and/or a control system), the efficiency of the application of the electric generation device is improved. For example, the electric generation device can be selectively engaged by the first clutch mechanism at an optimal time to recover rotational energy from the wheel and/or wheel axle (e.g. when the transport refrigeration system is travelling downhill), and selectively disengaged at a non-optimal time (e.g. when the transport refrigeration system is accelerating).

The transport refrigeration system may comprise a power management module in electrical communication with the energy storage device, the electric generation device and the first clutch mechanism; wherein the power management module is configured to operate the first clutch mechanism based on data from one or more sensors.

The power management module may be an electronic controller including a processor and an associated memory comprising computer-executable instructions that, when executed by the processor, cause the processor to perform various operations. The processor may be but is not limited to a single-processor or multi-processor system of any of a wide array of possible architectures, including field programmable gate array (FPGA), central processing unit (CPU), application specific integrated circuits (ASIC), digital signal processor (DSP) or graphics processing unit (GPU) hardware arranged homogenously or heterogeneously. The memory may be a storage device such as, for example, a random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic or any other computer readable medium.

By controlling the first clutch mechanism based on data from one or more sensors the system can select the optimal time to harvest electrical energy from the rotational energy of the wheel and/or the wheel axle. For example, it may be desired to recover rotational energy from the wheel and/or the wheel axle during deceleration of the vehicle when braking is applied, and/or during downhill travel of the vehicle, and/or during controlled stopping manoeuvres when the vehicle is brought to a complete rest. This improved selectivity and/or control increases both the efficiency and safety of the system.

However, during an emergency stopping manoeuvre, the response time of an electronic control module may not be fast enough in order to avoid inadvertently driving the wheel and/or wheel axle via the rotational inertia of the rotor of the electric generation device. Thus, the action of the first and a second clutch mechanism, one providing selective control during normal operation of the electric generation system and the other providing a mechanical failsafe during emergency stopping, combine synergistically to improve overall safety and efficiency of the system.

The transport refrigeration system may further comprise a rotational velocity sensor configured to detect a rotational velocity of the wheel and/or wheel axle and in electrical communication with the power management module; wherein the first clutch mechanism is operable to engage the electric generation device with the wheel and/or the wheel axle to generate electrical power responsive to a deceleration of the wheel and/or wheel axle being greater than a predetermined deceleration.

The transport refrigeration system may further comprise a pitch sensor configured to detect a pitch angle of the transport refrigeration system and in electrical communication with the power management module; wherein the first clutch mechanism is operable to engage the electric generation device with the wheel and/or the wheel axle to generate electrical power responsive to the pitch angle being less than a predetermined pitch angle.

The transport refrigeration system may further comprise a rotational velocity sensor configured to detect a rotational velocity of the electric generation device and in electrical communication with the power management module; wherein, when the electric generation device is operably engaged with the wheel and/or the wheel axle, the power management module is configured to decrease a torque limit of the electric generation device responsive to a deceleration of the electric generation device being greater than a predetermined deceleration.

The torque limit may be decreased for a selected period of time.

The torque limit may be decreased until the rotational velocity of the electric generation device increases to a predetermined rotational velocity.

According to a second aspect of the invention there is provided a method of operating a transport refrigeration system, the method comprising: powering a transportation refrigeration unit using an energy storage device; charging the energy storage device using an electric generation device operably connected through a mechanical interface to at least one of a wheel of the transport refrigeration system and a wheel axle of the transport refrigeration system, wherein the mechanical interface comprises a first clutch mechanism and a second clutch mechanism, and wherein charging the energy storage device using the electric generation device comprises: operating the first clutch mechanism to engage the electric generation device with the wheel and/or the wheel axle to generate electrical power; and when a rotational velocity of the electric generation device is greater than a rotational velocity of the wheel and/or the wheel axle, disengaging the electric generation device from the wheel and/or the wheel axle by the second clutch mechanism, wherein the second clutch mechanism is an overrunning clutch.

The method may further comprise operating the first clutch mechanism to disengage the electric generation device from the wheel and/or the wheel axle.

The method may further comprise operating the first clutch mechanism using a power management module; wherein the power management module is in electrical communication with the energy storage device, the electric generation device and the first clutch mechanism; and wherein the power management module operates the first clutch mechanism based on data from one or more sensors.

The method may further comprise: detecting a rotational velocity of the wheel and/or wheel axle using a rotational velocity sensor; and operating the first clutch mechanism, using the power management module, to engage the electric generation device with the wheel and/or the wheel axle to generate electrical power responsive to a deceleration of the wheel and/or wheel axle being greater than a predetermined deceleration.

The method may further comprise: detecting a pitch angle of the transport refrigeration system using a pitch sensor; and operating the first clutch mechanism, using the power management module, to engage the electric generation device with the wheel and/or the wheel axle to generate electrical power responsive to the pitch angle being less than a predetermined pitch angle.

The method may further comprise: detecting a rotational velocity of the electric generation device using a rotational velocity sensor; and when the electric generation device is operably engaged with the wheel and/or the wheel axle, decreasing, using the power management module, a torque limit of the electric generation device.

The method may further comprise increasing the torque limit after a selected period of time.

The method may further comprise increasing the torque limit when the rotational velocity increases to a selected rotational velocity.

A preferred embodiment of the present invention will now be described in greater detail, by way of example only and with reference to the drawings, in which:.

<FIG> shows a transport refrigeration system <NUM>. <FIG> shows an enlarged schematic illustration of a transport refrigeration unit <NUM> suitable for use in the transport refrigeration system <NUM>. <FIG> shows an enlarged schematic illustration of an electric generation device <NUM> suitable for use in the transport refrigeration system <NUM>.

The transport refrigeration system <NUM> is illustrated as a trailer system <NUM>, as seen in <FIG>. The trailer system <NUM> includes a vehicle <NUM> including an operator's compartment or cab <NUM> and a propulsion motor <NUM> which acts as the drive system of the trailer system <NUM>. The propulsion motor <NUM> is configured to power the vehicle <NUM>. The energy source that powers the propulsion motor <NUM> may be at least one of compressed natural gas, liquefied natural gas, gasoline, electricity, diesel, or a combination thereof. The propulsion motor <NUM> may be an electric motor or a hybrid motor (e.g., a combustion engine and an electric motor).

The trailer system <NUM> includes a transport container <NUM> coupled to the vehicle <NUM>. The transport container <NUM> may be integrated with the vehicle <NUM> (e.g. a non-trailer refrigeration such as, for example a rigid truck, a truck having refrigerated compartment) or removably coupled to the vehicle <NUM> (e.g. a tractor-trailer refrigerated system). In <FIG>, the transport container <NUM> is a refrigerated trailer and includes a top wall <NUM>, a directly opposed bottom wall <NUM>, opposed side walls <NUM>, and a front wall <NUM>, with the front wall <NUM> being closest to the vehicle <NUM>. The transport container <NUM> further includes a door or doors <NUM> at a rear wall <NUM>, opposite the front wall <NUM>. The walls of the transport container <NUM> define a refrigerated cargo space <NUM>.

Typically, transport refrigeration systems <NUM> are used to transport and distribute perishable goods and environmentally sensitive goods (herein referred to as perishable goods <NUM>). The perishable goods <NUM> may include but are not limited to fruits, vegetables, grains, beans, nuts, eggs, dairy, seed, flowers, meat, poultry, fish, ice, blood, pharmaceuticals, or any other suitable cargo requiring temperature controlled transport. The transport refrigeration system <NUM> includes a transportation refrigeration unit <NUM>, a refrigerant compression device <NUM>, an electric motor <NUM> for driving the refrigerant compression device <NUM>, and a controller <NUM>. The transportation refrigeration unit <NUM> is in operative association with the refrigerated cargo space <NUM> and is configured to provide conditioned air to the transport container <NUM>. The transportation refrigeration unit <NUM> functions, under the control of the controller <NUM>, to establish and regulate one or more desired environmental parameters, such as, for example temperature, pressure, humidity, carbon dioxide, ethylene, ozone, light exposure, vibration exposure, and other conditions in the interior compartment <NUM>, as known to one of ordinary skill in the art. In an embodiment, the transportation refrigeration unit <NUM> is capable of providing a desired temperature and humidity range.

The transportation refrigeration unit <NUM> includes a refrigerant compression device <NUM>, a refrigerant heat rejection heat exchanger <NUM>, an expansion device <NUM>, and a refrigerant heat absorption heat exchanger <NUM> connected in refrigerant flow communication in a closed loop refrigerant circuit and arranged in a conventional refrigeration cycle. The transportation refrigeration unit <NUM> also includes one or more fans <NUM> associated with the refrigerant heat rejection heat exchanger <NUM> and driven by fan motor(s) <NUM> and one or more fans <NUM> associated with the refrigerant heat absorption heat exchanger <NUM> and driven by fan motor(s) <NUM>. The transportation refrigeration unit <NUM> may also include a heater <NUM> associated with the refrigerant heat absorption heat exchanger <NUM>. In an embodiment, the heater <NUM> may be an electric resistance heater. It is to be understood that 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 <NUM> 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 across flow path to the heat outlet <NUM>. The fan(s) <NUM> are operative to pass air, typically ambient air, across the tubes of the refrigerant heat rejection heat exchanger <NUM> to cool refrigerant vapor passing through the tubes. The refrigerant heat rejection heat exchanger <NUM> may operate either as a refrigerant condenser, such as if the transportation refrigeration unit <NUM> is operating in a subcritical refrigerant cycle or as a refrigerant gas cooler, such as if the transportation refrigeration unit <NUM> is operating in a transcritical cycle.

The refrigerant heat absorption heat exchanger <NUM> 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 across flow path from a return air inlet <NUM>. The fan(s) <NUM> are operative to pass air drawn from the refrigerated cargo space <NUM> across the tubes of the refrigerant heat absorption heat exchanger <NUM> 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 <NUM> is supplied back to the refrigerated cargo space <NUM> through a refrigeration unit outlet <NUM>. 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.

Airflow is circulated into and through the refrigerate cargo space <NUM> of the transport container <NUM> by means of the transportation refrigeration unit <NUM>. A return airflow <NUM> flows into the transportation refrigeration unit <NUM> from the refrigerated cargo space <NUM> through the refrigeration unit return air intake <NUM>, and across the refrigerant heat absorption heat exchanger <NUM> via the fan <NUM>, thus conditioning the return airflow <NUM> to a selected or predetermined temperature. The conditioned return airflow <NUM>, now referred to as supply airflow <NUM>, is supplied into the refrigerated cargo space <NUM> of the transport container <NUM> through the refrigeration unit outlet <NUM>. Heat <NUM> is removed from the refrigerant heat rejection heat exchanger <NUM> through the heat outlet <NUM>. The transportation refrigeration unit <NUM> may contain an external air inlet <NUM>, as shown in <FIG>, to aid in the removal of heat <NUM> from the refrigerant heat rejection heat exchanger <NUM> by pulling in external air <NUM>. The supply airflow <NUM> may cool the perishable goods <NUM> in the refrigerated cargo space <NUM> of the transport container <NUM>. It is to be appreciated that the transportation refrigeration unit <NUM> can further be operated in reverse to warm the container system <NUM> when, for example, the outside temperature is very low. In the illustrated embodiment, the return air intake <NUM>, the refrigeration unit outlet <NUM>, the heat outlet <NUM>, and the external air inlet <NUM> are configured as grilles to help prevent foreign objects from entering the transportation refrigeration unit <NUM>.

The transport refrigeration system <NUM> also includes a controller <NUM> configured for controlling the operation of the transport refrigeration system <NUM> including, but not limited to, the operation of various components of the refrigerant unit <NUM> to provide and maintain a desired thermal environment within the refrigerated cargo space <NUM>. The controller <NUM> may also be able to selectively operate the electric motor <NUM>. The controller <NUM> may be an electronic controller including a processor and an associated memory comprising computer-executable instructions that, when executed by the processor, cause the processor to perform various operations. The processor may be but is not limited to a single-processor or multi-processor system of any of a wide array of possible architectures, including field programmable gate array (FPGA), central processing unit (CPU), application specific integrated circuits (ASIC), digital signal processor (DSP) or graphics processing unit (GPU) hardware arranged homogenously or heterogeneously. The memory may be a storage device such as, for example, a random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic or any other computer readable medium.

The transportation refrigeration unit <NUM> is powered by the energy storage device <NUM>, which provides electrical power to the transportation refrigeration unit <NUM> and will be discussed further below. Examples of the energy storage device <NUM> may include a battery system (e.g., a battery or bank of batteries), fuel cells, flow battery, and others devices capable of storing and outputting electric energy that may be DC. The energy storage device <NUM> may include a battery system, which may employ multiple batteries organized into battery banks.

The energy storage device <NUM> may be charged by a stationary charging station <NUM> such as, for example a wall 48V power outlet. The charging station <NUM> may provide single phase (e.g., level <NUM> charging capability) or three phase AC power to the energy storage device <NUM>. It is understood that the charging station <NUM> may have any phase charging and embodiments disclosed herein are not limited to single phase or three phase AC power. In an embodiment, the single phase AC power may be a high voltage DC power, such as, for example, 500VDC.

The energy storage device <NUM> may be located outside of the transportation refrigeration unit <NUM>, as shown in <FIG>, or the energy storage device <NUM> may be located within the transportation refrigeration unit <NUM>. The transportation refrigeration unit <NUM> has a plurality of electrical power demand loads on the energy storage device <NUM>, including, but not limited to, the drive motor <NUM> for the fan <NUM> associated with the refrigerant heat rejection heat exchanger <NUM>, and the drive motor <NUM> for the fan <NUM> associated with the refrigerant heat absorption heat exchanger <NUM>. As each of the fan motors <NUM>, <NUM> and the electric motor <NUM> may be an AC motor or a DC motor, it is to be understood that various power converters <NUM>, such as AC to DC rectifiers, DC to AC inverters, AC to AC voltage/frequency converters, and DC to DC voltage converters, may be employed in connection with the energy storage device <NUM> as appropriate. In the depicted embodiment, the heater <NUM> also constitutes an electrical power demand load. The electric resistance heater <NUM> may be selectively operated by the controller <NUM> whenever a control temperature within the temperature controlled cargo box drops below a preset lower temperature limit, which may occur in a cold ambient environment. In such an event the controller <NUM> would activate the heater <NUM> to heat air circulated over the heater <NUM> by the fan(s) <NUM> associated with the refrigerant heat absorption heat exchanger <NUM>. The heater <NUM> may also be used to de-ice the return air intake <NUM>. Additionally, the electric motor <NUM> being used to power the refrigerant compression device <NUM> also constitutes a demand load. The refrigerant compression device <NUM> may comprise a single-stage or multiple-stage compressor such as, for example, a reciprocating compressor or a scroll compressor. The transport refrigeration system <NUM> may also include a voltage sensor <NUM> to sense the voltage from the energy storage device <NUM>.

As described above the energy storage device <NUM> is used to electrically power the transportation refrigeration unit <NUM>. The energy storage device <NUM> is integrated within an energy management system <NUM>. The energy management system <NUM> comprises an electric generation device <NUM>, the energy storage device <NUM> configured to provide electrical power to electric motor <NUM>, the electric motor <NUM> configured to power the transportation refrigeration unit <NUM>, a power management module <NUM>, and one or more sensors <NUM>.

The electric generation device <NUM>, as shown in <FIG>, is configured to harvest electrical power from kinetic energy of the trailer system <NUM>. The electric generation device <NUM> as shown comprises an axle generator (the electric generation device <NUM> is mounted on or operably connected to a wheel axle 365a of the trailer system <NUM>) configured to recover rotational energy when the transport refrigeration system <NUM> is in motion and convert that rotational energy to electrical energy, such as, for example, when the axle <NUM> of the trailer system <NUM> is rotating during acceleration, cruising, or braking. However, the electric generation device <NUM> may alternatively or additionally comprise a hub generator (mounted on or operably connected to a wheel <NUM> of the trailer system <NUM>). The electric generation device <NUM> supplies the generated electrical power to the energy storage device <NUM>.

It is understood that the electric generation device <NUM> may be mounted on any wheel <NUM> or axle <NUM> of the trailer system <NUM> and the mounting location of the electric generation device <NUM> illustrated in <FIG> is one example of a mounting location.

The electric generation device <NUM> is operably connected to the wheel axle 365a through a mechanical interface <NUM>. The mechanical interface <NUM> operably engages the wheel axle 365a with the electric generation device <NUM> to enable the transmission of rotational movement from the wheel axle 365a to a drive/input shaft of the electric generation device <NUM>. For example, the mechanical interface <NUM> may comprise a gear box and/or a drive train.

The mechanical interface <NUM> comprises a first (e.g. primary) clutch mechanism <NUM>. The first clutch mechanism <NUM> is operable to selectively engage the electric generation device <NUM> with the wheel axle 365a (and/or wheel 364a). In other words, the first clutch mechanism <NUM> controls when rotational movement is transmitted to the electric generation device <NUM> and when the electric generation device <NUM> is able to generate electrical power to charge the energy storage device <NUM>.

The mechanical interface <NUM> also comprises a second (e.g. secondary) clutch mechanism <NUM>. The second clutch mechanism <NUM> is an overrunning clutch (sometimes referred to as a freewheel). The overrunning clutch <NUM> is configured to disengage the electric generation device <NUM> from the wheel axle 365a (and/or wheel 364a) when a rotational velocity of the input shaft of the electric generation device <NUM> is greater than a rotational velocity of the wheel axle 365a (and/or wheel 364a).

During normal operation of the electric generation device <NUM>, the first clutch mechanism <NUM> is controlled to engage the electric generation device <NUM> with the wheel axle 365a (and/or wheel 364a) when it is desired to extract rotational kinetic energy from the wheel axle 365a. The first clutch mechanism <NUM> may be manually controlled by an operator of the transport refrigeration system <NUM>, e.g. a driver. However, preferably, the first clutch mechanism <NUM> is controlled by the power management module <NUM>.

The power management module <NUM> is in electrical communication with the energy storage device <NUM>, the electric generation device <NUM>, the first clutch mechanism <NUM>, and one or more sensors <NUM>. The power management module <NUM> controls the first clutch mechanism <NUM> to engage the electric generation device <NUM> with the wheel axle 365a (and/or wheel 364a) based on data received from at least one of the energy storage device <NUM>, the electric generation device <NUM> and the one or more sensors <NUM>.

The power management module <NUM> uses the data received from at least one of the energy storage device <NUM>, the electric generation device <NUM> and the one or more sensors <NUM> to determine when it is a good time to extract rotational kinetic energy from the wheel axle 365a (and/or wheel 364a).

For example, the one or more sensors <NUM> comprise a rotational velocity sensor configured to detect a rotational velocity of the wheel 364a and/or the wheel axle 365a. The rotational velocity sensor is configured to identify a deceleration of the vehicle <NUM>. The rotational velocity sensor is in operative association with the vehicle <NUM> and may detect when a brake <NUM> of the vehicle <NUM> is being applied to slow the vehicle <NUM> and/or the vehicle <NUM> is decelerating without the brakes <NUM> being applied (i.e., driver lets foot off accelerator pedal). The power management module <NUM> is configured to control the first clutch mechanism <NUM> to engage the electric generation device <NUM> when the deceleration is greater than a selected deceleration, which may indicate that some propulsion motor <NUM> rotation is no longer needed to drive the vehicle <NUM>, and it is a good time to bleed off some rotational energy of the wheels <NUM> and/or axles <NUM> of the trailer system <NUM> using the electric generation device <NUM>. Bleeding off rotational energy of the wheels <NUM> or axles <NUM> when the vehicle <NUM> is decelerating helps reduce any performance impact to the ability of the propulsion motor <NUM> to power the vehicle <NUM>.

The one or more sensors <NUM> may comprise an inertial pitch sensor configured to detect a pitch angle of the vehicle <NUM>. The power management module <NUM> is configured to control the first clutch mechanism <NUM> to engage the electric generation device <NUM> when the when the pitch angle is less than a selected pitch angle, which may indicate that some propulsion motor <NUM> rotation is no longer needed to drive the vehicle <NUM> and it is a good time to bleed off some rotational energy of the wheels <NUM> and/or axles <NUM> of the trailer system <NUM> using the electric generation device <NUM>. For example, when the vehicle <NUM> is descending downhill with a negative pitch angle, gravity assists in driving the vehicle <NUM> downhill and the full capacity of the rotational energy of the wheels <NUM> and/or axles <NUM> may no longer be needed to drive the vehicle <NUM>. Bleeding off rotational energy of the wheels <NUM> and/or axles <NUM> when the vehicle <NUM> is descending downhill helps reduce any performance impact to the ability of the propulsion motor <NUM> to power the vehicle <NUM>.

The power management module <NUM> may detect a state of charge of the energy storage device <NUM> and determine whether the energy storage device <NUM> may take additional charge (i.e. electrical power). For example, the power management module <NUM> may detect that the state of charge of the energy storage device <NUM> is less than a selected state of charge (e.g., <NUM>% charged). If the power management module <NUM> detects that the state of charge of the energy storage device <NUM> is less than a selected state of charge then the power management module <NUM> may increase the torque limit of the electric generation device <NUM> for a selected period of time if the transport refrigeration system <NUM> is also detected to be decelerating and/or going downhill (i.e. free energy). The selected period of time may be short enough, such that the electric generation device <NUM> does not overheat. Advantageously, temporarily raising the torque limit of the electric generation device <NUM> for a selected period of time allows the electric generation device <NUM> to generate as much electric power as possibly when the energy is "free" and there is space in the energy storage device <NUM>. As discussed above, energy may be considered "free" when the vehicle <NUM> is moving downhill or decelerating.

The one or more sensors may comprise a rotational velocity sensor configured to detect a rotational velocity of (the rotor of) the electric generation device <NUM>. The power management module <NUM> is configured to monitor the rotational velocity of the electric generation device <NUM> to detect wheel <NUM> slippage using the rotational velocity sensor. The rotational velocity sensor of the electric generation device <NUM> may be a sensor mechanically connected to the electric generation device <NUM> to detect rotational velocity of the electric generation device <NUM>, or may be an electronic sensor electrically connected to the electric generation device <NUM> to detect rotational velocity of the electric generation device <NUM> by measuring the electrical frequency output of the electric generation device <NUM>. In another embodiment, the rotational velocity sensor may be an inverter connected to the electric generation device <NUM> to detect rotational velocity of the electric generation device <NUM> by measuring the electrical frequency output of the electric generation device <NUM>. In yet another embodiment, the rotational velocity sensor may be a wireless sensor capable of detecting rotational velocity of the electric generation device <NUM> wirelessly, such as, for example, RFID tracking, wireless capacitive sensor, wireless electromagnetic induction sensor, or any other wireless detection method known to one of skill in the art.

The power management module <NUM> is configured to detect and monitor the accelerations and decelerations of the electric generation device <NUM> in order to detect wheel <NUM> slippage. Sudden or rapid deceleration of the electric generation device <NUM> may indicate that the wheel 364a of the trailer system <NUM> has lost grip with the road surface below and the wheel 364a (e.g., tire) has started slipping. The power management module <NUM> is configured to decrease the torque limit of the electric generation device <NUM> when the rotational velocity of the electric generation device <NUM> decelerates greater than a selected deceleration. If the electric generation device <NUM> decelerates too fast, this may be indicative of wheel 364a slippage, thus the torque limit of the electric generation devices <NUM> may be temporarily lowered until the wheel 364a is able to regain traction with the road surface. Decreasing the torque limit of the electric generation device <NUM> will cap the rotational velocity of the wheel 364a, thus allowing the wheel 364a to slow down and regain traction.

While the above control is suitable for normal operation of the transport refrigeration system <NUM> (e.g. controlled deceleration of the vehicle <NUM> and/or downhill travel of the vehicle <NUM>), a situation may arise where the vehicle <NUM> of the transport refrigeration system <NUM> must carry out an emergency stop. During an emergency stopping manoeuvre of the vehicle <NUM> the wheels <NUM> and wheel axles <NUM> must be brought to a complete rest as soon as possible. However, if the electric generation device <NUM> is engaged with a wheel axle 365a and/or a wheel 364a by the first clutch mechanism <NUM> when an emergency stopping manoeuvre is initiated, the electric generation device <NUM> can inadvertently drive the wheel axle 365a and/or the wheel 364a (as a result of at least one of the rotational inertia of the electric generation device <NUM>, generator motoring of the electric generation device <NUM>, and/or other undesirable effects) even while the brake <NUM> of the vehicle <NUM> is being applied. This can result in reduced effectiveness of the braking in an emergency stopping situation (which is unsafe) and can also put unnecessary stress on the mechanical interface <NUM> and the brake <NUM>.

Thus, when the rotational velocity of the electric generation device <NUM> is greater than a rotational velocity of the wheel axle 365a and/or wheel 364a, as may be the case during an emergency stopping manoeuvre, the second clutch mechanism <NUM> automatically disengages the electric generation device <NUM> from the wheel axle 365a (and/or wheel 364a).

The second clutch mechanism <NUM>, as an overrunning clutch, is able to instantaneously and automatically disconnect the electric generation device <NUM> from the wheel axle 365a. The overrunning clutch <NUM> is a simple mechanical device that does comprise any externally controllable components. For example, the overrunning clutch <NUM> may be a sprag clutch, a roller ramp clutch, a wrap spring clutch or a wedge ramp clutch.

The overrunning clutch <NUM> may be positioned to automatically disengage the mechanical interface <NUM> from the wheel axle 365a and/or wheel 364a, or may be positioned to automatically disengage the mechanical interface <NUM> from the electric generation device <NUM>.

Claim 1:
A transport refrigeration system (<NUM>, <NUM>) comprising:
a transportation refrigeration unit (<NUM>);
an energy storage device (<NUM>) configured to provide electrical power to the transportation refrigeration unit (<NUM>); and
an electric generation device (<NUM>) operably connected through a mechanical interface (<NUM>) to at least one of a wheel (<NUM>) of the transport refrigeration system (<NUM>, <NUM>) and a wheel axle (<NUM>) of the transport refrigeration system (<NUM>, <NUM>);
wherein the mechanical interface (<NUM>) comprises:
a first clutch mechanism (<NUM>) operable to selectively engage the electric generation device (<NUM>) with at least one of the wheel (<NUM>) and the wheel axle (<NUM>) to generate electrical power to charge the energy storage device (<NUM>); and characterised in that the mechanical interface (<NUM>) comprises:
a second clutch mechanism (<NUM>), wherein the second clutch mechanism is an overrunning clutch configured to disengage the electric generation device (<NUM>) from the wheel (<NUM>) and/or the wheel axle (<NUM>) when a rotational velocity of the electric generation device (<NUM>) is greater than a rotational velocity of the wheel (<NUM>) and/or the wheel axle (<NUM>).