Air conditioning system

An air conditioning system includes an evaporator, a compressor, a condenser, a valve an energy recovery device and at least one bypass passage. The compressor is fluidly connected to the evaporator. The condenser is fluidly connected to the compressor. The valve is configured to control flow of high-pressure refrigerant exiting the condenser. The energy recovery device has an inlet and an outlet. The inlet is fluidly connected to the valve to receive high-pressure refrigerant and the outlet is fluidly connected to the evaporator to deliver low-pressure refrigerant thereto. The energy recovery device is configured to extract work from flow of refrigerant therethrough. When the valve is closed and refrigerant flow cutoff, suction power loss is reduced by introduction of one or both of high-pressure refrigerant or low pressure refrigerant via one or more bypass passages.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air conditioning system. More specifically, the present invention relates to an air conditioning system with an energy recovery device that extracts work from expanding refrigerant moving from a high-pressure zone to a lower pressure zone of the air conditioning system.

2. Background Information

Air conditioning systems and heat pump systems are continuously being re-designed and modified in order to improve energy efficiency of such systems.

One such improvement is described in U.S. Pat. No. 6,272,871 wherein an air conditioning system is provided with an energy recovery device. The energy recovery device is basically a vane-type expander that is located downstream from a compressor (a high pressure zone) and downstream from an expansion valve. The energy recovery device is further located upstream from an evaporator (a low pressure zone) of the air conditioning system. High-pressure refrigerant from the compressor is released by the expansion valve and flows through the expander prior to reaching the evaporator. The expansion of the high-pressure refrigerant within the expander causes the expander to rotate, thereby producing rotary motion (work). The rotation of the expander can be used, for example, to provide supplemental rotary power to the compressor. Alternatively, the expander can be connected to a generator to produce electrical current.

The expander extracts work from the expanding refrigerant in a simple manner. The expander basically includes a housing having a chamber with an inner surface, a shaft mounted rotor within the chamber and a plurality of sliding vanes supported within slots in the rotor. The inner surface of the chamber is offset from the shaft that supports the rotor. The vanes can be biased by springs within the slot of the rotor to press against the inner surface of the housing chamber. As the rotor rotates, the vanes slide radially outward but are confined by the inner surface of the chamber. Since the shaft and rotor are axially offset from the center of the chamber, the volume of the space between any two adjacent vanes changes (increases or decreases) as the rotor rotates. The volume of the space between adjacent vanes proximate an inlet side of the chamber is smaller. The volume of the space between adjacent vanes proximate an outlet side of the chamber is larger. The expanding refrigerant migrates toward the outlet side rotating the rotor thus producing work.

In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved air conditioning system that further improves the operation and efficiency of air conditioning systems. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.

SUMMARY OF THE INVENTION

It has been discovered that in an air conditioning systems that employs an expander as an energy recovery device, the rotor of the expander slows down or stops rotating under certain conditions, thereby loosing momentum. Specifically, when the flow of high-pressure refrigerant the expander is stopped, vacuum or suction is produced between adjacent vanes moving from a lower volume area of the expander to a larger volume area of the expander. This suction effects the rotation of the expander and can act as a brake, slowing or stopping rotation of the expander, resulting in a phenomenon referred to as suction loss (energy loss resulting from suction). As a result, rotary momentum of the rotor of the expander is retarded causing a loss of energy and a loss of potential work produced from the energy recovery device.

One object of the invention is to reduce and/or eliminate the suction loss that occurs in energy recovery devices such as an expander in an air conditioning system.

In accordance with one aspect of the present invention, an air conditioning system is provided with an evaporator, a compressor, a condenser, a valve (expansion valve or throttling valve) an energy recovery device and a bypass passage. The compressor is fluidly connected to the evaporator to compress low-pressure refrigerant exiting the evaporator to high-pressure refrigerant. The condenser is fluidly connected to the compressor to receive the high-pressure refrigerant and dissipate heat therefrom. The valve is configured to control flow of high-pressure refrigerant exiting the condenser. The energy recovery device has an inlet fluidly connected to the valve to receive high-pressure refrigerant and an outlet fluidly connected to the evaporator to deliver low-pressure refrigerant thereto. The energy recovery device is also configured to extract work from flow of refrigerant therethrough. The bypass passage is located downstream from the inlet of the energy recovery device and upstream from the outlet of the energy recovery device. The bypass passage is also configured to deliver an auxiliary flow of refrigerant to the energy recovery device to reduce suction power loss.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially toFIG. 1, an air conditioning system10is illustrated in accordance with a first embodiment of the present invention. The air conditioning system10is suitable for use in a motor powered vehicle or a stationary heat pump/air conditioning system. The air conditioning system10includes an energy recovery device12that extracts energy (work) from expansion of refrigerant as the refrigerant moves from a high-pressure zone of the air conditioning system10to a low-pressure zone of the air conditioning system10. The energy recovery device12includes a lock-up prevention feature, described in greater detail below.

As shown schematically inFIG. 1, the air conditioning system10basically includes an evaporator14, a compressor16, a condenser18, a valve20, low-pressure lines22and24, high-pressure lines26and28, a bypass line30, a control unit32and the energy recovery device12. The compressor16, the high-pressure line26, the condenser18and the high-pressure line28generally define the high-pressure zone of the air conditioning system10. The outlet side of the energy recovery device12, the low pressure line22, the evaporator14and the low-pressure line24generally define the low-pressure zone of the air conditioning system10.

The evaporator14is a conventional element of the air conditioning system10and serves to absorb heat outside the evaporator14. The evaporator14can include a blower or fan which forces air past the evaporator14for improved heat transfer. Heat in the moving air is in turn absorbed by low-pressure refrigerant within the evaporator14. Optimally, the refrigerant within the evaporator14is a vapor state, or a liquid-vapor state. The low-pressure line24fluidly connects the evaporator14to the compressor16.

Refrigerant exiting the evaporator14is directed to the compressor16via the low-pressure line24. The compressor16preferably compresses the refrigerant in a conventional manner into high-pressure refrigerant in the vapor state. The high-pressure refrigerant compressed by the compressor16exits the compressor16via the high-pressure line26. The high-pressure line26is further fluidly connected to the condenser18in a conventional manner.

The condenser18can include a blower or fan that forces air past the condenser18for improved heat transfer. Hence, the high-pressure refrigerant within the condenser18is cooled by airflow in a conventional manner. The cooled high-pressure refrigerant is then directed to the valve20via the high-pressure line28, in a conventional manner. As indicated inFIG. 2, the high-pressure line28has an internal diameter D1.

Returning again toFIG. 1, the valve20is operable to selectively release the high-pressure refrigerant into the energy recovery device12. The valve20acts as a throttling device to promote cavitation of the high-pressure refrigerant as it enters a low volume space within the energy recovery device12. The valve20is preferably configured to operate with little pressure drop. In other words, when open, the valve20allows for a significant flow of high pressure refrigerant into the energy recovery device12in order to maximize the amount of work extracted from the expanding refrigerant moving from the high pressure line28toward the low pressure line22. However, it should be understood from the drawings and the description herein that the actual operation of the valve20and the level of flow of refrigerant therethrough are design considerations that depend upon such factors as the configuration of the air conditioning system10, the cooling/heating loads placed upon the air conditioning system10and the work desired or required from the energy recovery device12. It should also be understood that the expansion of refrigerant within the energy recovery device12causes a corresponding drop in refrigerant pressure as the refrigerant moves to the low pressure zone of the air conditioning system10.

The valve20is preferably connected to the control unit32. The control unit32preferably includes a microprocessor that is connected to a pressure sensor34, a temperature sensor36and a user input panel38. The pressure sensor34is preferably mounted to the low-pressure line24and detects refrigerant pressure within the low-pressure line24. The temperature sensor36is preferably located proximate the evaporator14in or on the low-pressure line24. Signals from the pressure sensor34and the temperature sensor36are processed by the control unit32. In response to measured pressure and/or temperature conditions, the control unit32opens and closes the valve20to maintain a desired pressure condition within the low-pressure line24and/or desired temperature proximate the evaporator14.

It should be understood that the temperature sensor36can be omitted and the control unit32can be connected to only the pressure sensor34in order to control the opening and closing of the valve20. In such a case, a conventional accumulator (not shown) can be added to low-pressure line24.

A primary purpose of the control unit32is to provide a cold evaporator temperature that is above the freezing point of water, while ensuring that the refrigerant entering the compressor is in the vapor phase. This facilitates good compression behavior at the compressor16and A/C cooling performance.

Hence, the valve20is connected to the control unit32(a microcomputer) that is further connected to at least one of the pressure sensor34and the temperature sensor36of the air conditioning system10and is configured to control the flow of high pressure refrigerant exiting the condenser18and entering the energy recovery device12.

The valve20selectively releases the high pressure refrigerant into the energy recovery device12allowing cavitation and expansion of the high pressure refrigerant as the refrigerant moves from the high pressure zone into the low pressure zone. Specifically, the refrigerant changes phase from a generally liquid phase to a part vapor/part liquid phase. The expansion of the refrigerant to a gaseous phase releases energy that is at least partially captured by the energy recovery device12to produce work, as described in greater detail below.

The bypass line30extends from the high-pressure line28to the energy recovery device12, thereby bypassing the valve20as described in greater detail below. The bypass line30preferably has an internal diameter D2, as shown inFIG. 2. The ratio of the internal diameter D1of the high-pressure line28to the internal diameter D2of the bypass line30is preferably approximately 100:1. Put another way, the ratio of the internal diameter D2of the bypass line30to the internal diameter D1of the high-pressure line28is preferably approximately 1:100.

It should be understood from the drawings and description herein that the actual ratio of the internal diameter D1to the internal diameter D2is a variable dimension dependent upon a variety of engineering factors, such as the cooling or heat transference capacity of the air conditioning system10, the amount of work anticipated or required from the energy recovery device12and/or the application of the air conditioning system10. For example, the air conditioning system10can be used in a vehicle (not shown), a heat pump system or air conditioning system in commercial building or household applications. In a vehicle, the energy recovery considerations and uses of work extracted by the energy recovery device12can be significantly different than those of an energy recovery device in an air conditioning system installed in a commercial building.

With specific reference toFIG. 2, a description of the energy recovery device12is now provided. The energy recovery device12is preferably a vane-type expander that uses the movement of high-pressure gas from the high-pressure zone of the air conditioning system10to the low-pressure zone and extracts energy in order to produce work. The energy recovery device12can be any of a variety of conventional expander devices, a specially made expander or conventional air motor that have been modified to accommodate the features of the present invention as described in greater detail below. Specifically, the energy recovery device12is configured to produce rotational movement from the flow of refrigerant therethrough.

As shown inFIG. 1, the energy recovery device12can be connected via a shaft S to a work utilizing device W which is an electricity generator in the depicted embodiment. However, it should be understood that the work-utilizing device W could be a fan (not shown) or a one-way clutch and gear assembly connected to the compressor16in order to take advantage of the rotational energy produced by the energy recovery device12.

As shown inFIG. 2, the energy recovery device12basically includes a housing40, an expansion chamber42, a rotor44, vanes46, an inlet48, an outlet50and a bypass port52. The expansion chamber42is formed within the housing40. The rotor44is rotatably supported within the expansion chamber42. The expansion chamber42includes an inner surface54. The expansion chamber42also includes a notch54athat extends along a portion of the inner surface54.

Typically, the rotor44rotates about an axis A that is off-center with respect to the expansion chamber42, as indicated inFIG. 2. The vanes46are slidably supported by the rotor44such that the vanes46can extend and retract relative to the inner surface54of the rotor44. For example, the rotor44can include recesses, one recess for each of the vanes46. Biasing springs (not shown) are disposed within each recess urging the vanes46radially outward such that the vanes46contact and press against the inner surface54of the expansion chamber42. The vanes46are spaced apart from one another by a prescribed or predetermined angular distance. In the energy recovery device12depicted inFIG. 2, there are six vanes angularly spaced apart by an angle of 60 degrees. It should be understood from the drawings and description herein that the number of vanes46is variable depending a variety of design considerations, such as air conditioning capacity, work to be extracted by the energy recovery device12and/or application of the air conditioning system10. For example, the energy recovery device12can have as few as four vanes or a larger number, if design requirements dictate an increased number. For instance, the energy recovery device12can include 30 or more vanes, if appropriate for the air conditioning system application.

The inlet48is open to the expansion chamber42and is further fluidly connected to the valve20such that when the valve20is open, high-pressure refrigerant passes from the valve20to the expansion chamber42of the energy recovery device12. The outlet50also is open to the expansion chamber42and is further fluidly connected to the low-pressure line22such that refrigerant expanding within the expansion chamber42exhausts to the low-pressure line22. Since the low-pressure line22is fluidly connected to the evaporator14, expanding refrigerant in the expansion chamber42passes through the outlet50, through the low-pressure line22and to the evaporator14.

Adjacent to the inlet48, the configuration and shape of the expansion chamber42is such that the volume of the space between adjacent pairs of vanes46is small. However, as the rotor44rotates, the volume between those same adjacent pairs of vanes46increases as the vanes46approach the outlet50. The volume of refrigerant between the moving vanes46similarly increases and pressure of the refrigerant decreases. The moving refrigerant pushes the vanes46from the portion of the expansion chamber42adjacent to the inlet48toward the outlet50. The movement of the refrigerant causes the rotor44to rotate and work is produced. When the valve20is shut, the flow of refrigerant is stopped and the rotor44stops in the absence of an auxiliary flow of refrigerant, due to suction generated between adjacent vanes46rotating toward the outlet50(where volume between adjacent vanes46is increasing). However, with an auxiliary flow of refrigerant entering the expansion chamber42via the bypass port52, rotation of the rotor44can continue, as explained in greater detail below.

The bypass port52(a bypass passage) extends through the housing40to the expansion chamber42. The bypass line30is fluidly connected to the bypass port52. The bypass port52and the bypass line30define a passage that extends from the high-pressure line28to the expansion chamber42. The dimensions of the bypass line30and the bypass port52are preferably the same, but depending upon design criteria, can have different internal dimensions. However, in the depicted embodiment, the bypass line30and bypass port52have internal diameters D2.

The bypass port52(the bypass passage) is located downstream from the inlet48and upstream from the outlet50of the energy recovery device12, as indicated inFIG. 2. The bypass port52and bypass line30are configured to deliver a continuous auxiliary flow of refrigerant to the energy recovery device12to reduce suction related power loss when the valve20is closed. Specifically, when the valve20shuts and the normal flow of refrigerant to the energy recovery device12stops, the rotor44does not come to a complete stop because of the auxiliary flow refrigerant from the bypass port52.

The auxiliary flow of refrigerant through the bypass port52and the bypass line30allows the rotor44to continue rotating. Specifically, the bypass line30and the bypass port52(the bypass passage) are configured to receive a restricted flow of high-pressure refrigerant from the high-pressure line28at a location downstream from the compressor16and upstream from the valve20. The bypass passage basically serves a rotor lock-up prevention feature.

An explanation of operation of the energy recovery device12when the valve20is shut is now provided with specific reference toFIGS. 2,3and4. As shown schematically inFIG. 2, a restricted flow of high-pressure refrigerant is provided to the space between an adjacent pair of the vanes46adjacent to a reference mark C on the rotor44. The high-pressure refrigerant expands causing (or allowing) the rotor44to continue rotating. With the rotor44in the position shown inFIG. 3, the volume of the space between the adjacent pair of the vanes46at the reference mark C has increased. As shown inFIG. 4, continued expansion of the refrigerant between the vanes46at the reference mark C exhaust to the outlet50and the low-pressure line22. With the auxiliary flow of refrigerant to the expansion chamber42, no suction is generated as the pair of vanes46at the reference mark C as the rotor44rotates. Hence, rotational momentum in the rotor44present at the time the valve20shuts is not lost and the rotor44can continue to rotate. Further, since the bypass port52is continuously supplied with a limited flow of high pressure refrigerant, the rotor44can continue to rotate as each adjacent pair of vanes46passes from a low volume side of the expansion chamber42adjacent to the inlet48to a high volume side of the expansion chamber42adjacent to the outlet50even though the valve20is shut.

It should be understood that the flow of high-pressure refrigerant through the bypass line30and the bypass port52into the expansion chamber42is generally small. As mentioned above, the internal diameter D2of the bypass line30and the bypass port52is preferably approximately one hundredth ( 1/100th) of the internal diameter D1the high pressure line28. Therefore, the flow of high-pressure refrigerant through the bypass port52is preferably limited.

Preferably, the flow through the bypass port52is sufficient to allow the rotor44to continue rotating, but insufficient to extract an appreciable amount of work. The primary purpose of the flow of high pressure refrigerant through the bypass port52into the expansion chamber42is to prevent significant braking forces due to suction from eliminating the rotational momentum present in the rotor44when the valve20is closed. In other words, the present invention is directed to a configuration, which allows for maintaining rotation of the rotor44when the valve20is closed.

The notch54athat extends along a portion of the inner-surface54is located on the volume decreasing side of the expansion chamber42. The notch54aprovides a gap between the vanes46and the inner surface54during volume reduction between adjacent vanes46thereby reducing or eliminating energy losses due to compression of gas or vapor located between adjacent vanes46as the volume therein decreases.

Second Embodiment

Referring now toFIG. 5, an energy recovery device212of an air conditioning system210shown in accordance with a second embodiment will now be explained. In view of the similarity between the first and second embodiments, the parts of the second embodiment that are identical to the parts of the first embodiment will be given the same reference numerals as the parts of the first embodiment. Moreover, the descriptions of the parts of the second embodiment that are identical to the parts of the first embodiment may be omitted for the sake of brevity. The parts of the second embodiment that differ from the parts of the first embodiment will be indicated with a single prime (′) or be given a new reference numeral.

In the second embodiment, the energy recovery device212includes many of the same features as in the first embodiment, such as the housing40, the expansion chamber42, the rotor44, the vanes46, the inlet48, the outlet50and the bypass port52. The energy recovery device212differs from the first embodiment in that a second bypass port60is added. The second bypass port60defines a second bypass passage. Further, a bypass line30′ replaces the bypass line30of the first embodiment. The bypass line30′ extends from the high-pressure line28and includes first and second tube branches62and64. The first tube branch62is fluidly connected to the bypass port52and the second tube branch64is fluidly connected to the second bypass port60.

The second bypass port60(second bypass passage) is located between the bypass port52(the first bypass passage) and the outlet50. The second bypass port60is configured to receive an auxiliary flow of high-pressure refrigerant to reduce suction power loss within the energy recovery device212. The second bypass port60and the bypass port52are angularly offset from one another by an angle that approximately corresponds to the angular offset between adjacent pairs of the vanes46, as indicated inFIG. 5. However, it should be understood from the description and the drawings herein that the separation or distance between the second bypass port60and the bypass port52is an engineering consideration that can depend upon a variety of factors, such as the number of vanes46provided in the energy recovery device212, the relative speeds of rotation of the rotor44with the valve20on and off and the optimal pressures at the inlet48and the outlet50, among other considerations.

Third Embodiment

Referring now toFIG. 6, an energy recovery device312of an air conditioning system310shown in accordance with a third embodiment will now be explained. In view of the similarity between the first, second and third embodiments, the parts of the third embodiment that are identical to the parts of the first and/or second embodiments will be given the same reference numerals as the parts of the first and/or second embodiments. Moreover, the descriptions of the parts of the third embodiment that are identical to the parts of the first and/or second embodiment may be omitted for the sake of brevity. The parts of the third embodiment that differ from the parts of the first embodiment will be indicated with a double prime (″) or be given a new reference numeral.

In the third embodiment, the energy recovery device312includes many of the same features as in the first and second embodiments, such as the housing40, the expansion chamber42, the inlet48, the outlet50and the bypass port52. The energy recovery device312differs from the first and second embodiments in that the energy recovery device312includes a plurality of bypass passages between the inlet48and the outlet50that are configured to receive corresponding auxiliary flows of refrigerant to reduce suction power loss within the energy recovery device312. The energy recovery device312also includes eight vanes46″ supported by a rotor44″, whereas in the first and second embodiments only six of the vanes46are depicted (seeFIGS. 2-4). An increase in the number of vanes requires a corresponding increase in the number of bypass passages.

Specifically, the energy recovery device312includes the bypass port52, a second bypass port70and a third bypass port72, defining three bypass passages. Further, a bypass line30″ replaces the bypass line30of the first embodiment. The bypass line30″ extends from the high-pressure line28and includes first, second and third tube branches74,76and78. The first tube branch74is fluidly connected to the bypass port52, the second tube branch76is fluidly connected to the second bypass port70and the third tube branch78is fluidly connected to the third bypass port72.

The bypass passages are offset from one another within the energy recovery device312by distances approximately corresponding to the angular offset between the adjacent ones of the vanes46″ of the energy recovery device312.

Fourth Embodiment

Referring now toFIG. 7, a portion of an air conditioning system410shown in accordance with a fourth embodiment will now be explained. In view of the similarity between the first and fourth embodiments, the parts of the fourth embodiment that are identical to the parts of the first embodiment will be given the same reference numerals as the parts of the first embodiment. Moreover, the descriptions of the parts of the fourth embodiment that are identical to the parts of the first embodiment may be omitted for the sake of brevity. The parts of the fourth embodiment that differ from the parts of the first embodiment will be indicated a new reference numeral.

In the fourth embodiment, the control unit32of the first embodiment has been replaced with a simple relay80for controlling opening and closing of the valve20. The relay80is connected to a pressure sensor82that is installed in either the low-pressure line22or the low-pressure line24(not shown inFIG. 7). When the pressure in the low-pressure line22falls below a prescribed level, the pressure sensor82provides a current or a voltage to the relay80allowing it to open the valve20. Once the pressure within the low-pressure line22has reached another prescribed level, the relay80shuts the valve20. Hence, the valve20is connected to the relay80that is configured to open the valve20in response to prescribed pressure conditions sensed by the pressure sensor82.

In accordance with the fourth embodiment, the energy recovery device12having the bypass passage defined by the bypass line30and the bypass port52is utilized in a simplified air conditioning system such as the air conditioning system410.

Fifth Embodiment

Referring now toFIGS. 8 and 9, a portion of an air conditioning system510shown in accordance with a fifth embodiment will now be explained. In view of the similarity between the first and fifth embodiments, the parts of the fifth embodiment that are identical to the parts of the first embodiment will be given the same reference numerals as the parts of the first embodiment. Moreover, the descriptions of the parts of the fifth embodiment that are identical to the parts of the first embodiment may be omitted for the sake of brevity. The parts of the fifth embodiment that differ from the parts of the first embodiment will be indicated a new reference numeral.

In the fifth embodiment, the energy recovery device512is the same as the energy recovery device12in the first embodiment except a bypass port152replaces the bypass port52of the first embodiment. The bypass port152of the fifth embodiment is significantly larger than the bypass port52of the first embodiment. Further, the bypass line30of the first embodiment has been eliminated in the air conditioning system510.

Instead, the air conditioning system510is provided with a bypass pipe130, a check valve132and a bypass line134. The bypass port152, the bypass pipe130, the check valve132and the bypass line134are configured to receive low pressure refrigerant from a section of the air conditioning system510downstream from the energy recovery device512. Specifically, in the air conditioning system510, the bypass pipe130is fluidly connected to the low-pressure line22. The bypass pipe130is further fluidly connected to the check valve132. The check valve132is fluidly connected to the bypass line134, which is fluidly connected to the bypass port152.

The bypass port152, the bypass pipe130, the check valve132and the bypass line134serve as a bypass passage that delivers low pressure refrigerant from the low pressure line22downstream from the energy recovery device512to the bypass port152.

The bypass port152, the bypass pipe130and the bypass line134preferably have an internal diameter D3and the low-pressure line22has an internal diameter D4. Preferably, the internal diameter D3is approximately half the size or less than that of the internal diameter D4. In other words, the ratio of the internal diameter D4to the internal diameter D3is approximately two to one (2:1).

In the air conditioning system510, suction power loss is eliminated or reduced by providing low-pressure refrigerant into the expansion chamber42. The check valve132is preferably a spring-biased valve that is biased to open when the vapor pressure within the bypass line134(and the bypass port152) is less than the vapor pressure within the bypass pipe130. Therefore, when suction develops within the space between adjacent vanes46that are exposed to the bypass port152, the check valve132opens and allows entry of low-pressure refrigerant. Hence, suction power loss is reduced or eliminated and the rotor44can continue to rotate when the valve20is closed.

Sixth Embodiment

Referring now toFIG. 10, a portion of an air conditioning system610shown in accordance with a sixth embodiment will now be explained. In view of the similarity between the fifth and sixth embodiments, the parts of the sixth embodiment that are identical to the parts of the fifth embodiment will be given the same reference numerals as the parts of the fifth embodiment. Moreover, the descriptions of the parts of the sixth embodiment that are identical to the parts of the fifth embodiment may be omitted for the sake of brevity. The parts of the sixth embodiment that differ from the parts of the fifth embodiment will be indicated a new reference numeral.

In the sixth embodiment, an energy recovery device612replaces the energy recovery device512of the fifth embodiment. The energy recovery device612of the air conditioning system610is identical to the energy recovery device512of the fifth embodiment except that a second bypass port154has been introduced that extends to the expansion chamber42. Further, a second check valve133is provided. The second check valve133is fluidly connected to a second bypass line136that extends from the second check valve133to the second bypass port154. The check valve132and the second check valve133operate in the same manner as described above with respect to the fifth embodiment, except that the second check valve133provides low pressure refrigerant to the second bypass port154.

Seventh Embodiment

Referring now toFIGS. 11 and 12, an air conditioning system710shown in accordance with a sixth embodiment will now be explained. In view of the similarity between the various embodiments, the parts of the seventh embodiment that are identical to the parts of the earlier embodiments will be given the same reference numerals as the parts of the earlier embodiments. Moreover, the descriptions of the parts of the seventh embodiment that are identical to the parts of the earlier embodiments may be omitted for the sake of brevity. The parts of the seventh embodiment that differ from the parts of the earlier embodiments will be indicated a new reference numeral.

In the seventh embodiment as shown inFIG. 12, the air conditioning system710is identical to the air conditioning system10of the first embodiment except that the air conditioning system710includes a bypass line730that replaces the bypass line30of the first embodiment and the air conditioning system710is configured to reduce or eliminate suction losses by providing both high pressure refrigerant and low pressure refrigerant to an energy recovery device712, as described below.

In the seventh embodiment, the energy recovery device12of the first embodiment is replaced with the energy recovery device712. The energy recovery device712is identical to the energy recovery device12, except for two changes. First, a first bypass port752replaces the bypass port52. Second, a second bypass port760has been added to the energy recovery device712. The second bypass port760is angularly displaced from the first bypass port752by a distance approximately corresponding to the angular distance between adjacent vanes46.

The first bypass port752is fluidly connected to the bypass line730and functions generally the same way that the bypass port52functions when the valve20is closed (as described above in the first embodiment). In the seventh embodiment, the bypass line730and the bypass port752both have an internal diameter D5that is preferably the same or smaller than the internal diameter D2of the bypass line30of the first embodiment. More specifically, the ratio of the internal diameter D1of the high-pressure line28to the internal diameter D5of the bypass line730is preferably greater than 1:100. In other words, the ratio of the internal diameter D5of the bypass line730to the internal diameter the high-pressure line28is preferably less than 1:100.

The air conditioning system710also includes from the fifth embodiment the bypass pipe130, the check valve132and the bypass line134. The second bypass port760is fluidly connected to the bypass line130which feeds low pressure refrigerant from the low-pressure line22to the expansion chamber42of the energy recovery device712. More specifically, adjacent spaces between adjacent pairs of vanes46of the expansion chamber of the energy recovery device712receive both high pressure and low pressure refrigerant when the valve20is closed in order to reduce or eliminate suction losses. The bypass line730can provide high pressure refrigerant to the energy recovery device712in the same manner as described above with respect to the first, second, third or fourth embodiments, only with a reduced volume due to the reduced internal diameter D5. The bypass pipe130, the check valve132and the bypass line134can provide low pressure refrigerant the bypass passage760in the same manner as described above with respect to the fifth and sixth embodiments.

In this manner, the space between a first pair of adjacent vanes46is provided with high pressure refrigerant and an adjacent space between another pair of adjacent vanes46is provided with low pressure refrigerant to reduce or eliminate suction losses. It should be understood from the description and drawings that an internal diameter D6of the bypass line134is larger than the internal diameter D5of the bypass line730.

It should be understood from the drawings and description herein that the configuration of the air conditioning system710and the energy recovery device712can be easily modified to include multiple bypass ports that provide high pressure refrigerant to a plurality of spaces between adjacent pairs of the vanes46in a manner similar to that described above in the second and third embodiments. Such increases in the number of bypass ports can be made depending upon the requirements of the overall air conditioning system and/or the overall design of the modified energy recovery device and the number of vanes provided in the modified energy recovery device. Similarly, the number of bypass ports providing low pressure refrigerant to the expansion chamber of the modified energy recovery device can likewise be increased, depending on the requirement of the system and modified energy recovery device, as mentioned above.

In each of the embodiments above that include a control unit, the control unit32preferably includes a microcomputer with an air conditioning system control program that controls the various embodiments of the air conditioning systems as discussed below. The control unit32can also include other conventional components such as an input interface circuit, an output interface circuit, and storage devices such as a ROM (Read Only Memory) device and a RAM (Random Access Memory) device. The memory circuit stores pressure and temperature parameters necessary for operation of air conditioning systems. The control unit32is operatively coupled to the air conditioning system components such as the valve20and/or the compressor16in a conventional manner.

It will be apparent to those skilled in the art from this disclosure that the precise structure and algorithms for the control unit32can be any combination of hardware and software that will carry out the functions of the present invention. In other words, “means plus function” clauses as utilized in the specification and claims should include any structure or hardware and/or algorithm or software that can be utilized to carry out the function of the “means plus function” clause.

The evaporator14, the compressor16, the condenser18, the valve20and the low and high pressure lines22,24,26and28are conventional components that are well known in the art. Since these air conditioning components are well known in the art, these structures will not be discussed or illustrated in detail herein. Rather, it will be apparent to those skilled in the art from this disclosure that the components can be any type of structure and/or programming that can be used to carry out the present invention.

GENERAL INTERPRETATION OF TERMS

The term “detect” as used herein to describe an operation or function carried out by a component, a section, a device or the like includes a component, a section, a device or the like that does not require physical detection, but rather includes determining, measuring, modeling, predicting or computing or the like to carry out the operation or function.