Patent Description:
Evaporators are commonly arranged within a refrigeration loop with an expansion valve upstream of the evaporator. The expansion valve configuration and operation affects the performance, efficiency, and capacity of the evaporator and the refrigeration system. Expansion valves can control the amount of liquid and vapor distributed to the evaporator. <CIT> discloses an electric expansion valve for a car air-conditioner. The opening degree of the electric expansion valve is controlled based on a control signal generated by the information of the detected pressure in a control unit. The flow rate of the cooling medium is controlled by regulating a duty ratio for opening and closing the valve port. <CIT> discloses a valve control system and a valve control method. <CIT> discloses a pulsed controlled solenoid flow control valve suitable for use in a closed vapor cycle air conditioning system. <CIT> discloses a heat exchanger.

One aspect of the present invention provides a method for disrupting a flow of refrigerant through a heat exchanger as defined in claim <NUM>. The method includes receiving, with a controller, a first signal from a first sensor, the first signal indicative of a pressure of the refrigerant flowing through the heat exchanger. The method includes setting, with the controller, an operating frequency of a valve based on the first signal. The valve regulates refrigerant flow through the heat exchanger. The operating frequency includes a rate at which the valve actuates between a first valve position that sets a first refrigerant flow rate through the heat exchanger and a second valve position that sets a second refrigerant flow rate through the heat exchanger. The method includes controlling, with the controller, operation of a solenoid to actuate the valve at the operating frequency. The refrigerant includes refrigerant in the liquid phase and refrigerant in the gaseous phase. Actuating the valve at the operating frequency disrupts the flow of the refrigerant through the heat exchanger such that when the valve is moved from the first valve position to the second valve position, the refrigerant in the liquid phase is more equally distributed through the heat exchanger.

Another aspect of the present invention provides a control system for disrupting a flow of refrigerant through a heat exchanger as defined in claim <NUM>. The control system comprises a valve for regulating the flow of refrigerant through the heat exchanger, a solenoid coupled to the valve that actuates the valve, and a first sensor that provides signals indicative of a pressure of the flow of refrigerant within the heat exchanger. The control system also includes a controller coupled to the solenoid and the sensor, the controller including an electronic processor and a memory. The controller is configured to receive a first signal from the first sensor and a second signal from the second sensor, set an operating frequency of the valve based on the first signal and the second signal, and control operation of the solenoid to actuate the valve at the operating frequency. The operating frequency includes a rate at which the valve actuates between a first valve position that sets a first refrigerant flow through the heat exchanger and a second valve position that sets a second refrigerant flow rate through the heat exchanger. The flow of refrigerant includes refrigerant in the liquid phase and refrigerant in the gaseous phase. Actuating the valve at the operating frequency disrupts the flow of the refrigerant through the heat exchanger such that, when the valve is moved from the first valve position to the second valve position, the refrigerant in the liquid phase is more equally distributed through the heat exchanger.

Another embodiment provides a heat exchanger assembly comprising a heat exchanger core, a valve, a solenoid, a first sensor, and a controller. The heat exchanger core includes a refrigerant channel, an inlet manifold, and an outlet manifold. The valve is configured to regulate refrigerant flow into the heat exchanger core. The solenoid actuates the valve between a first valve position that sets a first refrigerant flow rate through the heat exchanger core and a second valve position that sets a second refrigerant flow rate through the heat exchanger core. The first sensor is configured to provide signals indicative of characteristics of the flow of refrigerant through the heat exchanger core. The controller includes an electronic processor and a memory. The controller is configured to receive a first signal from the first sensor and a second signal from the second sensor, set an operating frequency of the valve based on the first signal and the second signal, and control operation of the solenoid to actuate the valve at the set operating frequency. The operating frequency is the rate at which the valve actuates between the first valve position and the second valve position.

Other features, aspects, and benefits of various embodiments of the present invention will become apparent by consideration of the detailed description and accompanying drawings.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The scope of the present invention is only defined by the appended claims.

A heat exchanger assembly of <FIG> includes a heat exchanger core <NUM> having plates <NUM> stacked to form alternating coolant channels <NUM> and refrigerant channels <NUM>. The coolant channels <NUM> and refrigerant channels <NUM> are in thermal contact with each other. The plates <NUM> extend from a bottom plate to a top plate <NUM>. The core <NUM> includes a coolant inlet and a coolant outlet. A connection block <NUM> extends from the top plate <NUM> of the core <NUM>, the connection block <NUM> being sealed to the core <NUM> by brazing, welding, or other joining methods. The connection block <NUM> includes an inlet <NUM> and an outlet. A connection block inlet channel <NUM> extends from the inlet <NUM> to an inlet manifold <NUM> of the core <NUM>.

A valve assembly <NUM> is provided on or in the connection block <NUM>. The valve assembly <NUM> includes a driving mechanism <NUM>, which may be a solenoid or motor, such as a stepper or servo motor. The driving mechanism <NUM> actuates a valve <NUM> to open and close the valve <NUM> to regulate a flow of refrigerant <NUM> into the core <NUM>. The valve assembly <NUM> has a valve assembly refrigerant channel <NUM> that is aligned with the connection block inlet channel <NUM> at least at one end of the valve assembly refrigerant channel <NUM> to provide refrigerant flow to the core <NUM>.

In some embodiments, the valve <NUM> is actuated in a pulsing manner to reset (e.g., disrupt) the flow of refrigerant and prevent an equilibrium state of the two phases (i.e., the gas and the liquid phase of the refrigerant <NUM>) of the refrigeration within the heat exchanger assembly. This mitigates the dry out of the refrigerant flow channels <NUM> within the core <NUM>. During an equilibrium state refrigerant channels <NUM> with more liquid refrigerant would have less pressure drop and are a path of least resistance for more liquid refrigerant flow. This lessens the flow of liquid (i.e., increases the drying out) of other refrigerant channels <NUM>. Pulsing or cycling the valve <NUM> prevents this condition and provides more equal distribution of liquid refrigerant to all of the refrigerant flow channels <NUM>. Additionally, pulsing or cycling the valve <NUM> improves the performance of the evaporator by providing the more equal distribution of liquid refrigerant to all of the refrigerant flow channels <NUM>.

<FIG> provides another embodiment where a distribution valve assembly <NUM> is located downstream of the valve assembly <NUM>. The distribution valve assembly <NUM> includes a first valve <NUM> that moves independently of an included second valve <NUM>. The first valve <NUM> has a first valve arm <NUM> with an inner channel. A second valve arm <NUM> is situated within the inner channel of the first valve arm <NUM> and translates by the second valve <NUM>. Both the first valve <NUM> and the second valve <NUM> are driven by a second driving mechanism (not shown). Springs <NUM>, <NUM> are included with the distribution valve assembly <NUM> to allow independent travel between the first valve <NUM> and the second valve <NUM>. The first and second valves can be seated against first and second valve seats <NUM>, <NUM>. <FIG> schematically shows the flow of refrigerant through the distribution valve assembly <NUM>. As shown in <FIG>, the flow of refrigerant <NUM> enters the distribution valve assembly <NUM> at both ends. The first and second valves <NUM>, <NUM> may be actuated such that the flow of refrigerant <NUM> is distributed to refrigerant channels <NUM> in a mostly liquid state, again being cycled to prevent an equilibrium of liquid and vaper within the heat exchanger.

<FIG> shows another embodiment of the heat exchanger assembly including an air to liquid heat exchanger core <NUM>. The core <NUM> includes an inlet manifold <NUM> and an outlet manifold <NUM>. Refrigerant flow tubes <NUM> extend between the inlet manifold <NUM> and the outlet manifold <NUM>. The valve assembly <NUM> of <FIG>, as discussed above, is fluidly connected to the inlet manifold <NUM> and is located upstream of the inlet manifold <NUM>. In some embodiments, the distribution valve assembly <NUM> of the alternative embodiment of <FIG> is also be included within this core <NUM>. In embodiments where the distribution valve assembly <NUM> is included, refrigerant connections (not shown) are included between the valve assembly <NUM> and the opposites sides of the inlet manifold <NUM> to provide the flow of refrigerant <NUM> to the opposite sides of the inlet manifold <NUM>. The distribution valve assembly <NUM> is actuated as described above. The flow of refrigerant <NUM> moves from the inlet manifold <NUM> through the tubes <NUM> to the outlet manifold <NUM> to transfer heat between air and the flow of refrigerant <NUM> within the tubes <NUM>. The flow of refrigerant then exits the core <NUM> at an outlet port of the outlet manifold <NUM>.

<FIG> and <FIG> depict another embodiment where the heat exchanger assembly includes a core <NUM> formed from a stack of plates <NUM>. The core <NUM> includes refrigerant inlet manifolds <NUM> and a refrigerant outlet manifold <NUM>. The core <NUM> also includes a coolant inlet manifold <NUM> and a coolant outlet manifold <NUM>. The plates <NUM> are stacked to provide refrigerant channels <NUM> that alternate with coolant channels <NUM> to transfer heat between adjacent refrigerant and coolant channels. This embodiment also includes the valve assembly <NUM> arranged upstream of the inlet manifolds <NUM>. The valve assembly <NUM> is controlled to cycle to reset the refrigerant preventing equilibrium of the liquid and vapor within the core. Thus, liquid flow is reset at the entrance of the inlet manifolds <NUM>. In some embodiments, the core <NUM> includes only a single inlet manifold <NUM>. Such embodiments may include the distribution valve assembly <NUM>, which is shown in <FIG> and operates as described above. Refrigerant lines (not shown) are provided from the valve assembly <NUM> to opposite sides of the distribution valve assembly <NUM>, which is contained within a valve housing or channel. The distribution valve assembly <NUM> selectively directs the flow of refrigerant to one of the inlet manifold <NUM>.

<FIG> provides a control system <NUM> for the heat exchanger assembly of <FIG>. The control system <NUM> includes a controller <NUM>, a compressor sensor <NUM>, a temperature sensor <NUM>, a pressure sensor <NUM>, and the driving mechanism <NUM>. In some embodiments, the control system <NUM> may include only a single one of the compressor sensor <NUM>, the temperature sensor <NUM>, the pressure sensor <NUM>, or otherwise any combination thereof. For example, in some preferred embodiments, the temperature sensor <NUM> and the pressure sensor <NUM> are included in the control system <NUM>. The controller <NUM> includes an electronic processor <NUM> (for example, a programmable microprocessor, a microcontroller, programmable logic controller, or other suitable device) and a memory <NUM>.

The memory <NUM> is a non-transitory computer readable medium that includes, for example, a program storage area and a data storage area. The program storage area and the data storage area can include combinations of different types of memory, for example read-only memory ("ROM"), random access memory ("RAM") (for example, dynamic RAM ["DRAM"], synchronous DRAM ["SDRAM"], etc.), electrically erasable programmable read-only memory ("EEPROM"), flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic memory devices. In one example, the electronic processor <NUM> is connected to the memory <NUM> and executes software instructions that are capable of being stored in a RAM of the memory <NUM> (for example, during execution), a ROM of the memory <NUM> (for example, on a generally permanent basis), or another non-transitory computer-readable medium. Software included in the implementation of the driving mechanism <NUM> can be stored in the memory <NUM>. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The electronic processor <NUM> is configured to retrieve from the memory <NUM> and execute, among other things, instructions related to the control processes and methods described herein.

The compressor sensor <NUM> is configured to provide signals to the controller <NUM> indicative of the rotation speed (e.g., a rate per minute [RPM]) of a compressor (not shown) that drives refrigerant through the heat exchanger assembly of <FIG>. The speed of the compressor impacts the overall pressure of the refrigerant in the heat exchanger assembly, which will impact the ratio of liquid versus gaseous refrigerant within the system. As a result, the compressor speed may indicate a total refrigerant capacity of the heat exchanger assembly even though the volume of the heat exchanger assembly remains fixed.

The temperature sensor <NUM> is configured to provide signals to the controller <NUM> indicative of a temperature of the refrigerant <NUM>. The temperature sensor <NUM> may detect the temperature of the refrigerant <NUM>, for example, at the inlet manifold <NUM>, the outlet manifold <NUM>, the refrigerant inlet manifolds <NUM>, the refrigerant outlet manifold <NUM>, or another location having a flow of the refrigerant <NUM>. The pressure sensor <NUM> is configured to provide signals to the controller <NUM> indicative of a pressure of the refrigerant <NUM>. The pressure sensor <NUM> may detect a pressure of the refrigerant <NUM>, for example, at the inlet manifold <NUM>, the outlet manifold <NUM>, the refrigerant inlet manifolds <NUM>, the refrigerant outlet manifold <NUM>, or another location.

As previously stated, the valve <NUM> may be actuated in a pulsing manner to reset (e.g., disrupt) the flow of refrigerant and prevent an equilibrium state of the two phases of the refrigerant within the heat exchanger assembly. <FIG> provides a method <NUM> performed by the controller <NUM> for resetting the flow of refrigerant. At block <NUM>, the controller <NUM> receives temperature signals from the temperature sensor <NUM>. The controller <NUM> may determine a temperature of the refrigerant <NUM> based on the temperature signals. At block <NUM>, the controller <NUM> receives pressure signals from the pressure sensor <NUM>. The controller <NUM> may determine a pressure of the refrigerant <NUM> based on the pressure signals. At block <NUM>, the controller <NUM> receives speed signals from the compressor sensor <NUM>. The controller <NUM> may determine a speed of the compressor based on the speed signals.

At block <NUM>, the controller <NUM> sets an operating frequency based on at least one of the temperature signals, the pressure signals, and the speed signals. For example, the memory <NUM> may store a control curve used by the controller <NUM> to set the operating frequency. The temperature of the refrigerant <NUM>, the pressure of the refrigerant <NUM>, and the speed of the compressor may be used as inputs to the control curve. The operating frequency may be set to a value between approximately <NUM> and <NUM>. In some embodiments, the operating frequency is set to a value between approximately <NUM> and <NUM>. When the operating frequency is set to <NUM>, the controller <NUM> may be configured to reset the valve <NUM> (and therefore flow of the refrigerant <NUM>) after a predetermined time period has been satisfied. For example, the controller <NUM> resets the valve <NUM> every <NUM> minutes, every <NUM> minutes, or the like.

At block <NUM>, the controller <NUM> controls opening and closing of the valve <NUM> (i.e., actuation of the valve <NUM>) according to the operating frequency. For example, the controller <NUM> may provide a pulse width modulation (PWM) signal having the set operating frequency to the driving mechanism <NUM> (e.g., the solenoid or motor). The valve <NUM> then opens and closes at a frequency equal to the operating frequency. In some embodiments, opening and closing the valve <NUM> includes moving the valve <NUM> from a minimum movement position (e.g., a first valve position) to a maximum movement position (e.g., a second valve position). For example, the valve <NUM> may move from a location that is <NUM>% of possible actuation (which allows no refrigerant flow or minimum refrigerant flow to pass through the valve <NUM>) to a location that is <NUM>% of possible actuation (which allows maximum refrigerant flow through the valve <NUM>). In other embodiments, opening and closing the valve <NUM> includes moving the valve <NUM> from a percentage of possible movement, such as from <NUM>% of possible actuation to <NUM>% of possible actuation. Flow rates through the valve <NUM> correlate to the percentage of possible movement of the valve. The correlation can be linear, exponential, or another correlation. A flow rate of the refrigerant <NUM> may be different at the first valve position than the second valve position. For example, when the first valve position is a closed position, the flow rate of the refrigerant <NUM> is significantly less than when compared to when the first valve position is a fully opened position.

At block <NUM>, the controller <NUM> continues to monitor and/or receive at least one new temperature, pressure, and new speed signals from the temperature sensor <NUM>, the pressure sensor <NUM>, and the compressor sensor <NUM>, respectively. At block <NUM>, the controller <NUM> adjusts the operating frequency based on the new temperature, pressure and speed signals. For example, the new temperature, pressure, and speed signals are compared to the control curve stored in the memory <NUM>. The controller <NUM> then returns to block <NUM> to control opening and closing of the valve <NUM> according to the adjusted operated frequency. In this manner, the controller <NUM> adjusts the operating frequency as conditions of the refrigerant <NUM> change throughout operation of the heat exchanger assembly.

In some embodiments, the controller <NUM> may only use a single one of the temperature signals, the pressure signals, or the speed signals to set the operating frequency of the valve <NUM>. For example, the control curve stored in the memory <NUM> may provide an operating frequency for a given temperature, a given pressure, or a given speed of the compressor. In other embodiments, the controller <NUM> may use any combination of two of the temperature, pressure, and speed signals to set the operating frequency of the valve <NUM>. In yet other embodiments, the controller <NUM> no sensor signal to set the operating frequency of the valve <NUM>, and instead sets and/or adjusts the operating frequency of the valve <NUM> based on a value stored in the memory <NUM>.

In some situations, control of the valve <NUM> to exactly <NUM>% of it's actuation range (e.g., the closed position) may be difficult. Further slamming of the valve <NUM> to the closed position may be detrimental to the system. Additionally, some systems may not be capable of precise actuation of the valve <NUM> to a given position. Accordingly, in some embodiments, the valve <NUM> includes an internal passage <NUM>, shown in <FIG> and <FIG>. <FIG> illustrates the valve <NUM> in an open position. When the valve <NUM> is opened, the internal passage <NUM> is in a closed position. <FIG> illustrates the valve <NUM> in a closed position. When the valve <NUM> is closed, the internal passage <NUM> is in an open position, and allows a metered flow of refrigerant <NUM> to pass through the valve <NUM>. The metered flow is dependent on the size (e.g., diameter) of the internal passage <NUM>. The metered flow functions to avoid the "slamming" full closure of the valve <NUM>, and thus extends the life of the system. Further, in cases where precise actuation of the system is not possible, the valve <NUM> can still operate to actuate the valve between extreme valve positions, which does not require precise actuation. However, the internal passage <NUM> functions such that the flow of refrigerant is subjected to a valve position between <NUM>% (the fully open position) and the metered flow (at the "closed" position). As a result, the valve <NUM> actuates between <NUM>% flow and the metered flow without precise control of the valve <NUM>.

<FIG> provides a pressure-enthalpy ("P-h") graph <NUM> for a given temperature. The pressure-enthalpy graph <NUM> illustrates how actuation of the valve <NUM> influences the cycle of pressure and enthalpy for the refrigerant <NUM>. The three indicated lines on the graph <NUM> represent three different operating positions of the valve <NUM>. The "target condition" represents the fixed position that a non-oscillating valve would be in. The "Valve max" and "Valve min" lines represent the two positions an oscillating valve as described herein would cycle between. The "Valve max" line on the P-h graph yields a minimum pressure drop through the valve <NUM> and the "Valve min" line on the P-h graph yields a maximum pressure drop through the valve <NUM>. By oscillating, the valve <NUM> achieves the "target condition" even though the valve <NUM> is not held in a fixed position.

Claim 1:
A method (<NUM>) for disrupting a flow of refrigerant (<NUM>) through a heat exchanger, the method (<NUM>) comprising:
receiving, with a controller (<NUM>), a first signal from a first sensor (<NUM>), the first signal indicative of a pressure of the refrigerant (<NUM>) flowing through the heat exchanger,
receiving, with the controller (<NUM>), a second signal from a second sensor (<NUM>), the second signal indicative of a temperature of the refrigerant (<NUM>),
setting, with the controller (<NUM>), an operating frequency of a valve (<NUM>) based on the first signal and the second signal, wherein the valve (<NUM>) regulates refrigerant (<NUM>) flow through the heat exchanger, and wherein the operating frequency includes a rate at which the valve (<NUM>) actuates between a first valve position that sets a first refrigerant flow rate through the heat exchanger and a second valve position that sets a second refrigerant flow rate through the heat exchanger, and
controlling, with the controller (<NUM>), operation of a solenoid (<NUM>) to actuate the valve (<NUM>) at the operating frequency,
wherein the refrigerant (<NUM>) includes refrigerant (<NUM>) in the liquid phase and refrigerant in the gaseous phase, and
wherein actuating the valve (<NUM>) at the operating frequency disrupts the flow of the refrigerant (<NUM>) through the heat exchanger such that when the valve (<NUM>) is moved from the first valve position to the second valve position, the refrigerant (<NUM>) in the liquid phase is more equally distributed through the heat exchanger.