Patent Description:
A climate control system, a transport climate control system (TCCS) for a transport unit (e.g., a truck, a container (such as a container on a flat car, an intermodal container, marine container, etc.), a box car, a semi-tractor, a bus, or other similar transport unit), etc. may be included on the transport unit to condition air of a climate controlled space (e.g., internal space, cargo space, etc.) of the transport unit. In some transport units, the climate control system can be installed externally (e.g., on a rooftop of the transport unit, on a front wall of the transport unit, etc.). The climate control system can provide a desired environment for cargo stored in the transport unit.

<CIT> describes a method of operating a refrigeration system including initiating a compressor shutdown operation, determining a difference in a saturation temperature at a port of a compressor of the refrigeration system and an ambient temperature and comparing the difference in the saturation temperature and ambient temperature with a threshold. If the difference in the saturation temperature and the ambient temperature is less than or equal to the threshold, a pump down operation is performed and if the difference in the saturation temperature and the ambient temperature exceeds the threshold, a compressor shutdown operation is completed.

This invention relates to a method according to claim <NUM> and a climate control system according to claim <NUM> for a transport unit. More specifically, the embodiments relate to methods and systems for supplemental flow control of working fluid through a transport climate control circuit.

In particular, the embodiments described herein stage operation of various valves in the transport climate control circuit relative to the starting and stopping of a compressor of the transport climate control circuit to provide increased flow control of working fluid within the transport climate control circuit. Accordingly, the embodiments described herein can provide tighter temperature control within a climate controlled space of the transport unit. That is, the embodiments described herein can reduce temperature swing fluctuations within the climate controlled space of the transport unit.

The embodiments described herein can provide supplemental flow control for a transport climate control circuit that includes a compressor with an auxiliary or intermediate suction port (also referred to as an economizer port, a vapor injection port, etc.) in combination with a main suction port and a discharge port.

The embodiments described herein can be used with a fixed speed (e.g., two-speed compressor) or a variable speed compressor. The embodiments described herein can reduce the flow of working fluid through the transport climate control circuit beyond what can be accomplished with a variable speed compressor.

The embodiments described herein can increase the amount of time the compressor is ON and/or the amount of time the compressor is OFF during a start-stop cooling cycle relative to a conventional start-stop cooling operation mode. Accordingly, the number of cycles that the compressor is turned ON and OFF during a set period of time can be reduced and the amount of time for a single cycle in which the compressor is turned ON and then OFF can be increased.

An advantage of the embodiments described herein is that increased capacity control of a compressor of the transport climate control circuit can be provided in order to improve temperature control in a climate controlled space of the transport unit. The embodiments described herein can also minimize relative power consumption of the compressor and thereby the power consumption of the climate control system. Also, the embodiments, described herein can improve startup conditions of the transport climate control circuit and thereby avoid, for example, hydraulic locking of the compressor due to too much liquid working fluid and/or wet working fluid foam entering the compressor. Further, the embodiments described herein can reduce a discharge pressure at the discharge port of the compressor.

In one embodiment, a method for providing supplemental flow control of working fluid through a transport climate control circuit during a start-stop cooling operation mode is provided. The climate control circuit is part of a climate control system that provides climate control within a climate controlled space of a transport unit. The transport climate control circuit includes a condenser, an expansion device, an evaporator, and a compressor with a main suction port, an auxiliary port and a discharge port. The method includes closing a main liquid suction solenoid valve disposed between a condenser and an evaporator of the transport climate control circuit when the compressor is OFF. The method also includes monitoring a climate controlled space temperature within the climate controlled space. When the monitored climate controlled space temperature is greater than or equal to a predetermined setpoint temperature, the method includes turning the compressor ON, and opening the main liquid suction solenoid valve when a suction pressure at a suction port of the compressor is less than or equal to a predetermined suction pressure threshold. When the monitored climate controlled space temperature is less than or equal to the predetermined setpoint temperature, the method includes turning the compressor OFF, and closing the main liquid suction solenoid valve.

In another embodiment, a climate control system for providing climate control within a climate controlled space of a transport unit is provided. The climate control system includes a controller and a transport climate control circuit. The transport climate control circuit includes a condenser, an expansion device, an evaporator, and a compressor that includes a main suction port, an auxiliary port, and a discharge port. The controller is configured to: close a main liquid suction solenoid valve disposed between the condenser and the evaporator of the transport climate control circuit when the compressor is OFF, and monitor a climate controlled space temperature within the climate controlled space. When the monitored climate controlled space temperature is greater than or equal to a predetermined setpoint temperature, the controller is configured to turn the compressor ON, and open the main liquid suction solenoid valve when a suction pressure at the suction port of the compressor is less than or equal to a predetermined suction pressure threshold. When the monitored climate controlled space temperature is less than or equal to the predetermined setpoint temperature, the controller is configured to turn the compressor OFF, and close the main liquid suction solenoid valve.

References are made to the accompanying drawings that form a part of this invention and which illustrate embodiments in which the systems and methods described in this specification can be practiced.

This invention relates generally to a climate control system for a transport unit. More specifically, the embodiments relate to methods and systems for supplemental flow control of working fluid through a transport climate control circuit.

In particular, the embodiments described herein stage operation of various valves in the transport climate control circuit relative to the starting and stopping of a compressor of the transport climate control circuit to provide increased flow control of working fluid within the transport climate control circuit.

An advantage of the embodiments described herein is that increased capacity control of a compressor of the transport climate control circuit can be provided in order to improve temperature control in a climate controlled space of the transport unit. The embodiments described herein can also minimize relative power consumption of the compressor and thereby the power consumption of the climate control system. Also, the embodiments, described herein can improve startup conditions of the transport climate control circuit and thereby avoid, for example, hydraulic locking of the compressor due to too much liquid working fluid and/or wet working fluid foam entering the compressor. Further, the embodiments described herein can reduce a discharge pressure at the discharge port of the compressor. Moreover, the embodiments described herein can minimize the amount of time the compressor is OFF in a start-stop cooling mode and increase the amount of time the compressor is ON in the start-stop cooling mode.

A climate control system may be generally configured to control one or more environmental conditions (e.g., temperature, humidity, atmosphere, air quality, etc.) in a climate controlled space (e.g., internal space, cargo space, etc.) of a transport unit (e.g., a truck, a container (such as a container on a flat car, an intermodal container, a marine container, etc.), a box car, a semi-tractor, etc.). Generally, the internal space of a transport vehicle can be supplied with fresh air (e.g., outside air) and/or conditioned air (e.g., air conditioned by a transport climate control circuit of the climate control system) by the climate control system.

<FIG> illustrates one embodiment of a climate controlled transport unit <NUM> attached to a tractor <NUM>. The climate controlled transport unit <NUM> includes a climate control system <NUM> for a transport unit <NUM>. The tractor <NUM> is attached to and is configured to tow the transport unit <NUM>. The transport unit <NUM> shown in <FIG> is a trailer. It will be appreciated that the embodiments described herein are not limited to tractor and trailer units, but can apply to any type of transport unit (e.g., a truck, a container (such as a container on a flat car, an intermodal container, a marine container, etc.), a box car, a semi-tractor, a bus, or other similar transport unit), etc..

The climate control system <NUM> includes a climate control unit (CCU) <NUM> that provides environmental control (e.g. temperature, humidity, air quality, etc.) within a climate controlled space <NUM> of the transport unit <NUM>. The climate control system <NUM> also includes a programmable climate controller <NUM> and one or more sensors (not shown) that are configured to measure one or more parameters of the climate control system <NUM> (e.g., an ambient temperature outside of the transport unit <NUM>, a space temperature within the climate controlled space <NUM>, an ambient humidity outside of the transport unit <NUM>, a space humidity within the climate controlled space <NUM>, etc.) and communicate parameter data to the climate controller <NUM>.

The CCU <NUM> is disposed on a front wall <NUM> of the transport unit <NUM>. In other embodiments, it will be appreciated that the CCU <NUM> can be disposed, for example, on a rooftop or another wall of the transport unit <NUM>. The CCU <NUM> includes a transport climate control circuit (see <FIG>) that connects, for example, a compressor, a condenser, an evaporator and an expansion valve to provide conditioned air within the climate controlled space <NUM>.

The climate controller <NUM> may comprise a single integrated control unit <NUM> or may comprise a distributed network of climate controller elements <NUM>, <NUM>. The number of distributed control elements in a given network can depend upon the particular application of the principles described herein. The climate controller <NUM> is configured to control operation of the climate control system <NUM> including the transport climate control circuit.

<FIG> illustrates a container <NUM> that includes a climate controlled space <NUM> that is conditioned by a climate control system <NUM>. The climate control system <NUM> includes a CCU <NUM> provided on a front wall <NUM> of the container <NUM>. The CCU <NUM> provides environmental control (e.g. temperature, humidity, air quality, etc.) within the climate controlled space <NUM>. In some embodiments, the CCU <NUM> can control a supply air temperature of supply air that is brought into the climate controlled space <NUM>. The CCU <NUM> includes a transport climate control circuit (see <FIG>) that connects, for example, a compressor, a condenser, an evaporator and an expansion valve to provide conditioned air within the climate controlled space <NUM>.

The climate control system <NUM> also includes a programmable climate controller <NUM> and one or more sensors (not shown) that are configured to measure one or more parameters of the climate control system <NUM> (e.g., an ambient temperature outside of the container <NUM>, a space temperature within the climate controlled space <NUM>, an ambient humidity outside of the container <NUM>, a space humidity within the climate controlled space <NUM>, etc.) and communicate parameter data to the climate controller <NUM>. The climate controller <NUM> is configured to control operation of the climate control system <NUM> including the transport climate control circuit.

<FIG> depicts a temperature-controlled straight truck <NUM> that includes a climate controlled space <NUM> for carrying cargo and a climate control system <NUM>. The climate control system <NUM> includes a CCU <NUM> that is mounted to a front wall <NUM> of the load space <NUM>. The CCU <NUM> is controlled via a climate controller <NUM> to provide climate control within the climate controlled space <NUM>. The CCU <NUM> can include, amongst other components, a transport climate control circuit (see <FIG>) that connects, for example, a compressor, a condenser, an evaporator and an expansion valve to provide climate control within the climate controlled space <NUM>.

The climate control system <NUM> also includes a programmable climate controller <NUM> and one or more sensors (not shown) that are configured to measure one or more parameters of the climate control system <NUM> (e.g., an ambient temperature outside of the truck <NUM>, a space temperature within the climate controlled space <NUM>, an ambient humidity outside of the truck <NUM>, a space humidity within the climate controlled space <NUM>, etc.) and communicate parameter data to the climate controller <NUM>. The climate controller <NUM> is configured to control operation of the climate control system <NUM> including the transport climate control circuit.

<FIG> depicts a temperature-controlled van <NUM> that includes a climate controlled space <NUM> for carrying cargo and a climate control system <NUM> for providing climate control within the climate controlled space <NUM>. The climate control system <NUM> includes a CCU <NUM> that is mounted to a rooftop <NUM> of the climate controlled space <NUM>. The climate control system <NUM> can include, amongst other components, a transport climate control circuit (see <FIG>) that connects, for example, a compressor, a condenser, an evaporator and an expansion valve to provide climate control within the climate controlled space <NUM>.

The climate control system <NUM> also includes a programmable climate controller <NUM> and one or more sensors (not shown) that are configured to measure one or more parameters of the climate control system <NUM> (e.g., an ambient temperature outside of the van <NUM>, a space temperature within the climate controlled space <NUM>, an ambient humidity outside of the van <NUM>, a space humidity within the climate controlled space <NUM>, etc.) and communicate parameter data to the climate controller <NUM>. The climate controller <NUM> is configured to control operation of the climate control system <NUM> including the transport climate control circuit.

<FIG> illustrates a schematic of a transport climate control circuit <NUM> for a climate control system, according to one embodiment. The transport climate control circuit <NUM> can be used, for example, with the climate control units <NUM>, <NUM>, <NUM> and <NUM> shown in <FIG>. The transport climate control circuit <NUM> can be controlled by a controller (e.g., the climate controllers <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG>).

The transport climate control circuit <NUM> includes a compressor <NUM>, a condenser <NUM>, a main thermal expansion device <NUM>, and an evaporator <NUM>. The transport climate control circuit <NUM> also includes a receiver <NUM>, an economizer heat exchanger <NUM>, a plurality of valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and an economizer expansion device <NUM>. As will be discussed in more detail below, in some embodiments the valve <NUM> and the expansion device <NUM> can be replaced with optional valve <NUM>' and optional expansion device <NUM>'.

The compressor <NUM> is configured to direct a working fluid (e.g., refrigerant) within the circuit <NUM>. The compressor <NUM> includes a main suction port <NUM>, an auxiliary suction port <NUM> and a discharge port <NUM>. It will be appreciated that the auxiliary port <NUM> can also be referred to as an economizer port, a vapor injection port, an intermediate suction port, etc..

In the embodiments described herein, the compressor <NUM> is configured to not operate or is incapable of operating as a digital compressor that can modulate (e.g., load and unload) the amount of working fluid being compressed at any given time. Accordingly, when the circuit <NUM> is instructed to operate at less than a full capacity, the compressor <NUM> operates in a start-stop cooling operation mode in which the compressor <NUM> cycles between being ON and OFF to control the amount of working fluid being compressed and directed through the circuit <NUM>. In some embodiments, the start-stop cooling operation mode can cause the compressor <NUM> to rapidly cycle between being ON and OFF.

The compressor <NUM> can be, for example, a screw compressor, a scroll compressor, a centrifugal compressor, etc. In some embodiments, the compressor <NUM> can be a two stage compressor in which the auxiliary suction port <NUM> is connected to the middle of the two stage compressor.

In some embodiments, the compressor <NUM> can be a fixed speed (e.g., two-speed) compressor. In other embodiments, the compressor <NUM> can be a variable speed compressor.

In operation, working fluid compressed by the compressor <NUM> is directed from the discharge port <NUM> to the condenser <NUM> via discharge line <NUM>. Working fluid passing through the condenser <NUM> is directed to the receiver <NUM> via a liquid line <NUM>. A first portion of the working fluid passing through the receiver <NUM> is directed through the economizer heat exchanger <NUM> to a main liquid solenoid valve <NUM> via a sub-cooled liquid line <NUM>. The working fluid then passes through the main liquid solenoid valve <NUM> and the main expansion device <NUM> to the evaporator <NUM>. The working fluid passing through the evaporator <NUM> is then directed to the main suction port <NUM> via a main suction line <NUM>. The circuit <NUM> also includes an expansion device bypass valve <NUM> that allows working fluid directed from the main liquid solenoid valve <NUM> to bypass the expansion device <NUM> and go to the evaporator <NUM>. In some embodiments, the expansion device bypass valve <NUM> can be sized to roughly match the mass flow of working fluid through the expansion device <NUM> when the compressor <NUM> is ON.

A second portion of the working fluid passing through the receiver <NUM> is directed via an economizer liquid line <NUM> through an economizer liquid solenoid valve <NUM> and an economizer expansion device <NUM> to the economizer heat exchanger <NUM> to provide heat exchange with the first portion of the working fluid. The second portion of the working fluid is then directed through an economizer suction line <NUM> to the auxiliary suction port <NUM>. The second portion of the working fluid can also be directed through an economizer bypass valve <NUM> to the main suction port <NUM> instead of the auxiliary suction port <NUM>.

A third portion of the working fluid passing through the receiver <NUM> is directed to a liquid injection valve <NUM> via a liquid injection line <NUM> and then to the auxiliary suction port <NUM>. In some embodiments, the liquid injection valve <NUM> can be a pulsing valve.

The circuit <NUM> also includes a hot gas bypass line <NUM> that directs working fluid from the discharge port <NUM> of the compressor <NUM> to a hot gas bypass valve <NUM> before being combined with the second portion of the working fluid directed to the economizer heat exchanger <NUM>.

In some embodiments, the main liquid solenoid valve <NUM> and the main expansion device <NUM> can be replaced with an electronic expansion valve with, for example, a stepper motor, a fast pulsing valve, etc..

In some embodiments, the circuit <NUM> can include a downstream economizer configuration in which the economizer liquid solenoid valve <NUM>, the economizer expansion device <NUM> and the economizer liquid line <NUM> are replaced with an optional downstream economizer liquid solenoid valve <NUM>', an optional downstream economizer expansion device <NUM>', and an optional downstream economizer liquid line <NUM>'. In operation, a portion of working fluid passing from the receiver <NUM> through the economizer heat exchanger <NUM> to the main liquid solenoid valve <NUM> can be redirected through the optional downstream economizer liquid line <NUM>' to the optional downstream economizer liquid solenoid valve <NUM>' and the optional downstream expansion device <NUM>' to the economizer heat exchanger <NUM> to provide heat exchange with the working fluid passing through the economizer heat exchanger <NUM> to the main liquid solenoid valve <NUM>.

In some embodiments, the economizer liquid solenoid valve <NUM>, the economizer expansion device <NUM> can be replaced with an electronic expansion valve with, for example, a stepper motor, a fast pulsing valve, etc. Similarly, the optional downstream economizer liquid solenoid valve <NUM>' and the optional downstream expansion device <NUM>' can be replaced with an electronic expansion valve with, for example, a stepper motor, a fast pulsing valve, etc. In these embodiments, the electronic expansion valve can be run with liquid working fluid over-feed thereby potentially rendering the liquid injection line <NUM> and the liquid injection valve <NUM> unnecessary.

The circuit <NUM> can also include one or more sensors to monitor, for example, a temperature or pressure at various points within the circuit <NUM>. According to the invention, the circuit <NUM> includes a pressure sensor that is configured to monitor a suction pressure of working fluid at the main suction port <NUM> of the compressor <NUM>.

It will also be appreciated that one or more fans (not shown) may be associated with each of the condenser <NUM> and the evaporator <NUM>. The condenser fan(s) can be configured to provide a heat exchange between the working fluid passing through the condenser <NUM> and ambient air from outside of the transport unit. The evaporator fan(s) can be configured to provide a heat exchange between the working fluid passing through the evaporator <NUM> and air within the climate controlled space. Operation of the circuit <NUM> is discussed below with respect to <FIG>.

<FIG> illustrates a flowchart of a method <NUM> for providing supplemental flow control of working fluid through the transport climate control circuit <NUM> during a start-stop cooling operation mode, according to a first embodiment.

The method <NUM> begins at <NUM> prior to initial startup of the compressor <NUM> whereby a controller (e.g., the climate controllers <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG>) closes the main liquid suction solenoid valve <NUM>. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller monitors a space temperature Tc within the climate controlled space (e.g., the climate controlled space <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG>). In some embodiments, the controller receives space temperature data from one or more temperature sensors provided within the climate controlled space. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller determines whether the monitored space temperature Tc is greater than or equal to a desired setpoint temperature Ts for the climate controlled space plus a tolerance value tol. The desired setpoint temperature Ts can be a predetermined temperature value that is inputted into the climate control system to maintain the cargo being stored within the climate controlled space. The tolerance value tol can be set to a value that provides stability during constant minor fluctuations in the space temperature Tc. In some embodiments, the tolerance value can be, for example, a value between <NUM> to <NUM>. When the monitored space temperature Tc is greater than or equal to the desired setpoint temperature Ts plus the tolerance value tol, the method <NUM> proceeds to <NUM>. When the monitored space temperature Tc is not greater than or equal to the desired setpoint temperature Ts plus the tolerance value tol, the method <NUM> proceeds to <NUM>.

At <NUM>, the controller instructs the compressor <NUM> to turn ON or remain ON depending on how the compressor <NUM> is operating. The method <NUM> then proceeds to <NUM>. Optionally, in some embodiments, where the economizer bypass valve <NUM> is being used to assist in supplemental flow control, the method <NUM> can proceed to <NUM>.

At <NUM>, the controller monitors a suction pressure PSUCT at the main suction port <NUM> of the compressor <NUM>. According to the invention, the controller receives suction pressure data from a pressure sensor configured to monitor pressure data at the main suction port <NUM>. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller determines whether the monitored suction pressure PSUCT is less than or equal to a pressure threshold PThresh. The pressure threshold PThresh is set to a value that determines whether the circuit <NUM> is close to a vacuum condition at the main suction port <NUM> of the compressor <NUM>. In some embodiments, the pressure threshold PThresh can be set to a value of <NUM> psig. When the monitored suction pressure PSUCT is less than or equal to a pressure threshold PThresh, the method <NUM> proceeds to <NUM>. When the monitored suction pressure PSUCT is not less than or equal to a pressure threshold PThresh, the method <NUM> proceeds back to <NUM>.

At <NUM>, the controller opens the main liquid suction solenoid valve <NUM> to allow working fluid exiting the receiver <NUM> to be directed to the main expansion device <NUM>. The method <NUM> then proceeds back to <NUM>.

At <NUM>, the controller determines whether the monitored space temperature TC is less than or equal to the desired setpoint temperature TS for the climate controlled space minus the tolerance value tol. In some embodiments, the tolerance value tol can be different from the tolerance value tol used at <NUM>. When the monitored space temperature Tc is less than or equal to the desired setpoint temperature TS minus the tolerance value tol, the method <NUM> proceeds to <NUM>. When the monitored space temperature Tc is not less than or equal to the desired setpoint temperature Ts minus the tolerance value tol, the method <NUM> proceeds to <NUM>.

At <NUM>, the controller determines whether the main liquid suction solenoid valve <NUM> is closed. When the controller determines that the main liquid suction solenoid valve <NUM> is closed, the method <NUM> proceeds to <NUM>. When the controller determines that the main liquid suction solenoid valve <NUM> is open, the method <NUM> proceeds to <NUM>. Optionally, in some embodiments, where the economizer bypass valve <NUM> is being used to assist in supplemental flow control, the method <NUM> can proceed to <NUM>.

At <NUM>, the controller ensures that the compressor is OFF or stops operation of (e.g., turns OFF) the compressor <NUM>. The method <NUM> then proceeds back to <NUM>. At <NUM>, the controller closes the main liquid suction solenoid valve <NUM> and then proceeds to <NUM>.

At <NUM>, the controller maintains the current operation of the compressor <NUM>. For example, if the compressor <NUM> is currently operating (e.g., the compressor <NUM> is ON), the controller maintains operation of the compressor <NUM>. On the other hand, if the compressor <NUM> is currently not operating (e.g., the compressor <NUM> is OFF), the controller maintains the compressor from operating. The method <NUM> then proceeds to <NUM>.

At optional <NUM>, the controller opens the economizer bypass valve <NUM>. In some embodiments, the controller also closes the economizer liquid solenoid valve <NUM> (or the optional downstream economizer liquid solenoid valve <NUM>'). Accordingly, the gaseous working fluid can escape the auxiliary port <NUM> and can be directed through the economizer bypass line <NUM> back to the main suction port <NUM>. In some embodiments, the economizer bypass valve <NUM> can be opened and closed based on how close the climate controlled space temperature Tc is to the desired setpoint temperature TS. That is, the economizer bypass valve <NUM> can be closed to increase the capacity of the compressor to bring the climate controlled space temperature TC closer to the desired setpoint temperature TS. In some embodiments, the controller can pulse the economizer bypass valve <NUM> instead of simply opening the economizer bypass valve at optional <NUM>. For example, the controller can pulse the economizer bypass valve <NUM> to approach a stepless climate control. In some embodiments, the amount of time that the economizer bypass valve <NUM> is closed during a pulse cycle can be proportional to the difference between the climate controlled space temperature TC and the desired setpoint temperature TS. The method <NUM> then proceeds to <NUM>.

At optional <NUM>, the controller determines whether the economizer bypass valve <NUM> is closed. When the controller determines that the economizer bypass valve <NUM> is closed, the method <NUM> can proceed to <NUM>. When the controller determines that the economizer bypass valve <NUM> is open, the method <NUM> can proceed to optional <NUM>. At <NUM>, the controller closes the economizer bypass valve <NUM> and then can proceed to <NUM>.

The method <NUM> allows for a delayed startup of the circuit <NUM> by starting the compressor <NUM> for a period of time before the main liquid suction solenoid valve <NUM> is opened. This can cause condensation buildup in the receiver <NUM> and the condenser <NUM> and cause liquid refrigerant to be emptied from the evaporator <NUM>. The circuit <NUM> can continue to buildup condensation in the receiver <NUM> and the condenser <NUM> and empty liquid refrigerant from the evaporator <NUM> until the main suction port <NUM> reaches a near vacuum condition. At that point, the main liquid suction solenoid valve <NUM> can be opened such that working fluid can be directed through the expansion device <NUM> and the evaporator <NUM>.

Accordingly, the method <NUM> can increase the amount of time the compressor <NUM> is ON and the amount of time that the compressor <NUM> is OFF during a start-stop cooling cycle relative to a conventional start-stop cooling operation mode. It will be appreciated that a conventional start-stop cooling operation mode merely provides that the compressor <NUM> be turned ON and OFF based on a monitored space temperature within the climate controlled space with the circuit <NUM> and either does not include the main liquid suction solenoid valve <NUM> or keeps the main liquid suction solenoid valve <NUM> open at all times during start-stop cooling operation. By increasing the amount of time the compressor <NUM> is ON and the amount of time that the compressor <NUM> is OFF during a start-stop cooling cycle, the number of cycles that the compressor <NUM> is turned ON and OFF during a set period of time can be reduced and the amount of time for a single cycle in which the compressor <NUM> is turned ON and then OFF can be increased.

When the method <NUM> also includes the optional economizer bypass option via <NUM>, <NUM> and <NUM>, the amount of time that the compressor <NUM> is ON can be further increased, thereby further reducing the number of cycles that the compressor is turned ON and OFF during a set period of time and further increasing the amount of time for a single cycle in which the compressor <NUM> is turned ON and then OFF.

<FIG> illustrates a flowchart of a method <NUM> for providing supplemental flow control of working fluid through the transport climate control circuit <NUM> during a start-stop cooling operation mode, according to a second embodiment.

The method <NUM> begins at <NUM> prior to initial startup of the compressor <NUM> whereby a controller (e.g., the climate controllers <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG>) instructs the compressor <NUM> to turn ON. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller monitors a space temperature TC within the climate controlled space (e.g., the climate controlled space <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG>). In some embodiments, the controller receives space temperature data from one or more temperature sensors provided within the climate controlled space. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller determines whether the monitored space temperature TC is less than or equal to the desired setpoint temperature TS for the climate controlled space minus the tolerance value tol. The desired setpoint temperature TS can be a predetermined temperature value that is inputted into the climate control system to maintain the cargo being stored within the climate controlled space. The tolerance value tol can be set to a value that provides stability during constant minor fluctuations in the space temperature TC. In some embodiments, the tolerance value can be, for example, a value between <NUM> to <NUM>. When the monitored space temperature TC is less than or equal to the desired setpoint temperature TS minus the tolerance value tol, the method <NUM> proceeds to <NUM>. When the monitored space temperature Tc is not less than or equal to the desired setpoint temperature Ts minus the tolerance value tol, the method <NUM> returns to <NUM>.

At <NUM>, the controller closes the main liquid suction solenoid valve <NUM>. The method <NUM> then proceeds to <NUM>. At <NUM>, the controller monitors a suction pressure PSUCT at the main suction port <NUM> of the compressor <NUM>. According to the invention, the controller receives suction pressure data from a pressure sensor configured to monitor pressure data at the main suction port <NUM>. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller stops operation of (e.g., turns OFF) the compressor <NUM>. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller monitors the space temperature TC within the climate controlled space. In some embodiments, the controller receives space temperature data from one or more temperature sensors provided within the climate controlled space. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller determines whether the monitored space temperature TC is greater than or equal to the desired setpoint temperature TS for the climate controlled space plus a tolerance value tol. In some embodiments, the tolerance value tol can be different from the tolerance value tol used at <NUM>. When the monitored space temperature TC is greater than or equal to the desired setpoint temperature TS plus the tolerance value tol, the method <NUM> proceeds to <NUM>. When the monitored space temperature TC is not greater than or equal to the desired setpoint temperature TS plus the tolerance value tol, the method <NUM> proceeds back to <NUM>.

The method <NUM> allows for a delayed shutdown of the circuit <NUM> by keeping the compressor <NUM> ON for a period of time with the main liquid suction solenoid valve <NUM> closed before the compressor <NUM> is turned OFF. This can cause condensation buildup in the receiver <NUM> and the condenser <NUM> and cause liquid refrigerant to be emptied from the evaporator <NUM>. The circuit <NUM> can continue to buildup condensation in the receiver <NUM> and the condenser <NUM> and empty liquid refrigerant from the evaporator <NUM> until the main suction port <NUM> reaches a near vacuum condition. At that point, the compressor <NUM> can be turned OFF.

Accordingly, the method <NUM> can increase the amount of time the compressor <NUM> is ON during a start-stop cooling cycle relative to a conventional start-stop cooling operation mode. A conventional start-stop cooling operation mode, as referred to herein, merely provides that the compressor <NUM> be turned ON and OFF based on a monitored space temperature within the climate controlled space with the circuit <NUM> either not including the main liquid suction solenoid valve <NUM> or keeping the main liquid suction solenoid valve <NUM> open at all times during a start-stop cooling operation.

<FIG> illustrates a flowchart of a method <NUM> for providing supplemental flow control of working fluid through the transport climate control circuit <NUM> during a start-stop cooling operation mode, according to a third embodiment.

The method <NUM> begins at <NUM> prior to initial startup of the compressor <NUM> whereby a controller (e.g., the climate controllers <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG>) monitors a space temperature Tc within the climate controlled space (e.g., the climate controlled space <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG>). In some embodiments, the controller receives space temperature data from one or more temperature sensors provided within the climate controlled space. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller determines whether the monitored space temperature TC is greater than or equal to a desired setpoint temperature TS for the climate controlled space plus a tolerance value tol. The desired setpoint temperature Ts can be a predetermined temperature value that is inputted into the climate control system to maintain the cargo being stored within the climate controlled space. The tolerance value tol can be set to a value that provides stability during constant minor fluctuations in the space temperature TC. In some embodiments, the tolerance value can be, for example, a value between <NUM> to <NUM>. When the monitored space temperature TC is greater than or equal to the desired setpoint temperature TS plus the tolerance value tol, the method <NUM> proceeds to <NUM>. When the monitored space temperature TC is not greater than or equal to the desired setpoint temperature Ts plus the tolerance value tol, the method <NUM> proceeds back to <NUM>.

At <NUM>, the controller instructs the compressor <NUM> to turn ON. The method <NUM> then proceeds to <NUM>. At <NUM>, the controller closes the expansion device bypass valve <NUM>. This prevents the working fluid from bypassing the expansion device <NUM> when being directed from the economizer heat exchanger <NUM> to the evaporator <NUM>. It will be appreciated that in some embodiments the controller can instruct the compressor <NUM> to turn ON and close the expansion device <NUM> at the same time.

In some embodiments, instead of the controller closing the expansion device bypass valve <NUM> at <NUM>, the controller can instruct the valve <NUM> to pulse open and closed. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller monitors the space temperature TC within the climate controlled space. The method then proceeds to <NUM>. At <NUM>, the controller determines whether the monitored space temperature TC is less than or equal to the desired setpoint temperature TS for the climate controlled space minus the tolerance value tol. In some embodiments, the tolerance value tol can be different from the tolerance value tol used at <NUM>. When the monitored space temperature TC is less than or equal to the desired setpoint temperature TS minus the tolerance value tol, the method <NUM> proceeds to <NUM>. When the monitored space temperature TC is not less than or equal to the desired setpoint temperature TS minus the tolerance value tol, the method <NUM> proceeds back to <NUM>.

At <NUM>, the controller stops operation of (e.g., turns OFF) the compressor <NUM>. The method <NUM> then proceeds to <NUM>. At <NUM>, the controller opens the expansion device bypass valve <NUM>. This allows working fluid to bypass the expansion device <NUM> when being directed from the economizer heat exchanger <NUM> to the evaporator <NUM>. The method <NUM> then proceeds to <NUM>.

At <NUM>, the controller instructs one or more evaporator fan(s) and/or one or more condenser fan(s) to continue operation while the compressor <NUM> is OFF.

The method <NUM> allows for working fluid in the form of hot liquid that is not throttled by the bypass the expansion device <NUM> to enter the evaporator <NUM>. This can supply heat to the evaporator <NUM>. Accordingly, the method <NUM> can increase the amount of time the compressor <NUM> is ON and decrease the amount of time the compressor is OFF during a start-stop cooling cycle relative to a conventional start-stop cooling operation mode. A conventional start-stop cooling operation mode merely provides that the compressor <NUM> be turned ON and OFF based on a monitored space temperature within the climate controlled space with the circuit <NUM> not including the expansion device bypass valve <NUM> or keeping the expansion device bypass valve <NUM> open at all times during start-stop cooling operation.

It will be appreciated that the features of the methods <NUM>, <NUM>, <NUM> can be combined to provide improved flow control of working fluid during a start-stop cooling operation mode of the transport climate control circuit <NUM>. That is, in some embodiments, delayed startup of the of the circuit <NUM> as provided in the method <NUM> can be combined with the delayed shutdown of the circuit <NUM> as provided in the method <NUM> and/or with expansion device bypass as provided in the method <NUM>. Also in some embodiments, the delayed shutdown of the circuit <NUM> as provided in the method <NUM> can be combined with expansion device bypass as provided in the method <NUM>. Further, in some embodiments, the delayed shutdown of the circuit <NUM> as provided in the method <NUM> and/or the expansion device bypass as provided in the method <NUM> can include an economizer bypass as provided at <NUM> in the method <NUM>.

The terminology used in this specification is intended to describe particular embodiments and is not intended to be limiting. The terms "a," "an," and "the" include the plural forms as well, unless clearly indicated otherwise. The terms "comprises" and/or "comprising," when used in this specification, indicate the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components.

Claim 1:
A method for providing supplemental flow control of working fluid through a transport climate control circuit (<NUM>) during a start-stop cooling operation mode, the climate control circuit (<NUM>) being part of a climate control system providing climate control within a climate controlled space (<NUM>, <NUM>, <NUM>, <NUM>) of a transport unit (<NUM>), the transport climate control circuit (<NUM>) including a condenser (<NUM>), an expansion device (<NUM>), an evaporator (<NUM>), and a compressor (<NUM>) with a main suction port (<NUM>), an auxiliary port (<NUM>) and a discharge port (<NUM>), the method comprising:
closing (<NUM>) a main liquid suction solenoid valve (<NUM>) disposed between a condenser (<NUM>) and an evaporator (<NUM>) of the transport climate control circuit (<NUM>) when the compressor (<NUM>) is OFF;
monitoring (<NUM>) a climate controlled space temperature (Tc) within the climate controlled space (<NUM>, <NUM>, <NUM>, <NUM>);
when (<NUM>) the monitored climate controlled space temperature (Tc) is greater than or equal to a predetermined setpoint temperature (Ts):
turning (<NUM>) the compressor (<NUM>) ON, and
opening (<NUM>) the main liquid suction solenoid valve (<NUM>) when (<NUM>) a suction pressure (Psuct) at the suction port (<NUM>) of the compressor (<NUM>) is less than or equal to a predetermined suction pressure threshold (Pthresh); and
when (<NUM>) the monitored climate controlled space temperature (Tc) is less than or equal to the predetermined setpoint temperature (Ts):
turning (<NUM>) the compressor (<NUM>) OFF, and
closing (<NUM>) the main liquid suction solenoid valve (<NUM>).