JP2009133319A - Displacement type expansion machine and fluid machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the deterioration of the efficiency of recovering power under a condition in which an actual expansion ratio is smaller than a design expansion ratio, when a displacement type expansion machine 60 is used for a vapor compressing type refrigerating cycle and the like. <P>SOLUTION: A communicating passage 72 is provided, which branches off from an inflow port 37 to an expansion chamber 62 and communicates with a suction/expansion process position of the expansion chamber 62. A part of high-pressure fluid on an inflow side to the expansion chamber 62 can be introduced to the expansion chamber 62. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a positive displacement expander including an expansion mechanism that generates power when a high-pressure fluid expands, and a fluid machine including the expander.

  Conventionally, as an expander that generates power by expanding a high-pressure fluid, a positive displacement expander such as a rotary expander is known (see, for example, Patent Document 1). This expander can be used to perform an expansion stroke of a vapor compression refrigeration cycle (see, for example, Patent Document 2).

  The expander includes a cylinder and a piston that revolves along the inner peripheral surface of the cylinder, and an expansion chamber formed between the cylinder and the piston is partitioned into a suction / expansion side and a discharge side. . As the piston revolves, the portion of the expansion chamber that is on the suction / expansion side is switched to the discharge side, and the portion that is on the discharge side is switched to the suction / expansion side in turn. The discharging action is performed simultaneously in parallel.

In the expander, the angle range of the suction process in which the high-pressure fluid is supplied into the cylinder during one rotation of the piston and the angle range of the expansion process in which the fluid is expanded are determined in advance. That is, in this type of expander, the expansion ratio (density ratio between the intake refrigerant and the exhaust refrigerant) is generally constant. The high pressure fluid is introduced into the cylinder in the angular range of the suction process, while the fluid is expanded at a predetermined expansion ratio in the remaining angular range of the expansion process, and the rotational power is recovered.
JP-A-8-338356 JP 2001-116371 A

  Thus, the positive displacement expander has a specific expansion ratio. On the other hand, in the vapor compression refrigeration cycle in which the above expander is used, the high pressure and low pressure of the refrigeration cycle change due to the temperature change of the object to be cooled and the temperature change of the object of heat dissipation (heating). Accordingly, the density of the refrigerant sucked and discharged from the expander also varies. Therefore, in this case, the refrigeration cycle is operated at an expansion ratio different from that of the expander, and as a result, the operation efficiency is lowered.

  For example, under the condition where the pressure ratio of the vapor compression refrigeration cycle is reduced, in other words, when the expansion ratio is reduced, the amount of refrigerant discharged from the compressor increases at the same rotational speed. However, in the expander, almost the same amount of refrigerant flows at the same rotation speed regardless of the expansion ratio. Therefore, under the condition that the actual expansion ratio is smaller than the design expansion ratio, the amount of refrigerant that can be passed through the expander is smaller than the amount of refrigerant from the compressor.

  On the other hand, in the device disclosed in Patent Document 2, a bypass passage is provided in parallel with the expander, and a flow rate control valve is provided in the bypass passage. Therefore, in this apparatus, it is possible to match the refrigerant flow rates on the compression stroke side and the expansion stroke side of the refrigeration cycle by flowing a part of the refrigerant through the bypass passage under the condition that the expansion ratio is small. However, if it does in this way, since the refrigerant | coolant which does not pass through an expander does not carry out an expansion | swelling work, the collection | recovery motive power by an expander will reduce and operating efficiency will fall.

  Further, under the condition of a lower expansion ratio than the design expansion ratio, there is a problem that overexpansion occurs in the expansion chamber, thereby reducing efficiency. Therefore, this point will be described.

  Generally, an expander is configured to obtain the maximum power recovery efficiency when an operation is performed at a design expansion ratio. FIG. 12 is a graph showing the relationship between the volume change of the expansion chamber and the pressure change under ideal operating conditions in the case of a carbon dioxide refrigerant whose high pressure becomes supercritical pressure. As shown in the figure, a high-pressure fluid having characteristics close to that of an incompressible fluid is supplied into the expansion chamber between points a and b, and starts expanding from point b. When the point b is passed, the supply of the high-pressure fluid stops, so that the pressure once drops rapidly to the point c, and then gradually decreases to the point d while expanding. Then, after the cylinder volume of the expansion chamber becomes maximum at the point d, when the volume is reduced on the discharge side, it is discharged to the point e. Thereafter, the process returns to point a, and the inhalation process of the next cycle is started. In the state of this figure, the pressure at the point d coincides with the low pressure of the refrigeration cycle.

  On the other hand, when the expander is used in an air conditioner, as described above, the actual expansion ratio of the refrigeration cycle is changed due to fluctuations in operating conditions such as switching between cooling operation and heating operation and changes in outside air temperature. The design expansion ratio of the cycle or the inherent expansion ratio of the expander may be exceeded. In particular, if the actual expansion ratio of the refrigeration cycle is smaller than the design expansion ratio, the internal pressure of the expansion chamber becomes lower than the low pressure of the refrigeration cycle, and overexpansion may occur in the expander. is there.

  FIG. 13 is a graph showing the relationship between the volume change of the expansion chamber and the pressure change at this time, and shows a state where the low-pressure pressure in the refrigeration cycle is higher than in the example of FIG. In this case, after the fluid is supplied into the cylinder between the points a and b, the pressure is reduced to the point d according to the natural expansion ratio of the expander. On the other hand, the low pressure of the refrigeration cycle is at a point d 'higher than the point d. Therefore, after the expansion process is completed, the refrigerant is pressurized from the point d to the point d 'in the discharge process, and further discharged to the point e', so that the suction process of the next cycle is started.

  In such a situation, internal consumption of power is performed in the expander for discharging the refrigerant. That is, at the time of occurrence of overexpansion, the recovered power can be obtained only for (area I) − (area II) shown in FIG. 13, and the recovered power is greatly reduced compared to the operating conditions of FIG.

  The present invention was devised in view of such problems, and an object of the present invention is to enable recovery of power in the expander even under conditions where the expansion ratio is small, and to eliminate overexpansion. This is to prevent the operating efficiency from being lowered.

  The present invention provides a communication passage (72) that branches from the fluid inflow side to the expansion chamber (62) and communicates with the suction / expansion process position of the expansion chamber (62), and from the communication passage (72) to the expansion chamber. In (62), the high-pressure fluid on the inflow side can be introduced.

Specifically, the first invention is premised on a positive displacement expander including an expansion mechanism (60) that generates power when the high-pressure fluid supplied to the expansion chamber (62) expands. The expander includes a communication passage (72) that branches from the fluid inflow side of the expansion chamber (62) and communicates with an initial position in the suction / expansion process of the expansion chamber (62). (72) is provided with a flow control mechanism (73) capable of continuously adjusting the flow rate of the fluid .

In the first aspect of the invention, for example, when the expansion ratio of the refrigeration cycle and the inherent expansion ratio of the expander coincide with each other, the flow control mechanism (73) is not opened and the communication passage (72) is closed. At this time, since the operation is performed at the design expansion ratio, power recovery by the expander is efficiently performed.

On the other hand, when the actual expansion ratio becomes smaller than the design expansion ratio with the change of the operating conditions, the flow control mechanism (73) is opened to operate. In this case, the refrigerant flows through the expander while adjusting the flow rate. Therefore, it is possible to flow all the refrigerant to the expander without changing the rotation speed, and the refrigerant that has bypassed the expander performs expansion work in the expander, so that the power recovery efficiency is improved. .

Further, in the present invention, in the state where overexpansion occurs in the expansion chamber (62), the state of overexpansion can be eliminated by opening the flow control mechanism (73) . That is, when overexpansion occurs, the pressure in the expansion chamber (62) is lower than the fluid outflow side, but by introducing a high-pressure fluid from the fluid inflow side to the expansion chamber (62) as an auxiliary, The pressure in the expansion chamber (62) can be increased to the pressure on the fluid outflow side. Therefore, in the present invention, the power consumption shown in the area II of FIG. 13 is not performed, and as shown in FIG. 14 and FIG. 15, the operation state is reached in which the refrigerant gradually expands to the point d ′ in the expansion process. This can also prevent the power recovery efficiency from being reduced during overexpansion .

In the first invention, when the expansion ratio of the refrigeration cycle and the expansion ratio of the expander coincide with each other, the flow control mechanism (73) is closed and the operation is performed. On the other hand, under the condition that the expansion ratio of the vapor compression refrigeration cycle is small, even if the refrigerant is bypassed by an expander conventionally, the flow rate of the refrigerant is adjusted by adjusting the opening of the flow control mechanism (73), It becomes possible to introduce the refrigerant into the expander. Thereby, the expansion | swelling work of a refrigerant | coolant is performed with an expander. Even in the state where overexpansion occurs in the expansion chamber (62), the fluid on the high pressure side can be introduced into the expansion chamber (62) by opening the flow control mechanism (73), and the pressure can be increased. The state of overexpansion can be eliminated.

According to a second aspect of the present invention, in the positive displacement expander of the first aspect, the expansion mechanism (60) is configured to perform an expansion stroke of a vapor compression refrigeration cycle.

  In the vapor compression refrigeration cycle, as described above, the high pressure and the low pressure vary depending on the operating conditions, and the actual expansion ratio changes accordingly. Therefore, under the condition that the expansion ratio is small, in the conventional expander, the power recovery efficiency is reduced by bypassing the refrigerant, whereas when the expander of the present invention is used, the efficiency decrease can be effectively suppressed.

Assuming an example in which an expansion ratio is approximately 4 during heating and approximately 3 during cooling for a refrigerant that is currently commonly used (for example, R410A), when an appropriate expansion ratio is selected during heating, overexpansion occurs during cooling. Occurs. In addition, overexpansion is more likely to occur when the cooling load is small during actual operation. On the other hand, in the second aspect of the present invention, the overexpanded state can be effectively eliminated by supplementarily introducing the fluid on the inflow side from the communication passage (72) into the expansion chamber (62). .

The third invention is the positive displacement expander of the first or second invention , wherein the expansion mechanism (60) performs an expansion stroke of a vapor compression refrigeration cycle in which the high pressure becomes a supercritical pressure. It is characterized by having.

In a supercritical cycle using CO ₂ or the like as a refrigerant, for example, the expansion ratio is about 3 at the time of heating and about 2 at the time of cooling, and the power loss at the time of cooling is lower than that of a refrigeration cycle using a refrigerant that is currently used generally growing. On the other hand, if the fluid on the inflow side is supplementarily introduced from the communication passage (72) into the expansion chamber (62), power loss can be effectively reduced.

According to a fourth aspect of the present invention, in the positive displacement expander of any one of the first to third aspects, the expansion mechanism (60) is a rotary expansion mechanism, and the rotational power is recovered by the expansion of the fluid. It is characterized by being configured. As the rotary expansion mechanism (60), an expansion mechanism (60) such as a swing piston type, a rolling piston type, or a scroll type can be adopted.

Further, the fifth aspect of the invention compresses fluid in the casing (31) by being driven by the positive displacement expander (60), the electric motor (40), and the positive displacement expander (60) and the electric motor (40). The positive displacement expander (60) is constituted by the positive displacement expander according to the fourth aspect of the present invention .

  In the present invention, in the fluid machine in which the compressor (50) and the expander (60) are integrated, the compressor (50) and the expander (60) generally rotate at the same rotational speed. In contrast, the efficiency of power recovery tends to be reduced, but the power recovery efficiency can be particularly effectively increased by introducing the refrigerant into the expander (60).

  According to the first invention, since the fluid can be supplementarily introduced into the expansion chamber (62) from the fluid inflow side, conventionally, the high-pressure fluid (refrigerant) bypasses the expansion mechanism (60). The fluid can be introduced into the expansion mechanism (60) under the condition of the low expansion ratio. As a result, the high-pressure fluid can always perform expansion work, and the power recovery efficiency is improved.

  Further, if the refrigerant is introduced into the expansion mechanism (60) under the condition that the overexpansion occurs, the overexpansion can be eliminated. Therefore, the power loss represented by the area II in FIG. 13 can be eliminated, and the power can be reliably recovered as shown in FIGS. In this way, power recovery efficiency can be increased under operating conditions in which overexpansion occurs.

Also, by providing a flow control mechanism (73) capable of continuously adjusting the flow rate of fluid in the communication passage (72), the expansion ratio of the vapor compression refrigeration cycle is reduced. When bypassing without flowing, the refrigerant can flow to the expander, so that the efficiency of power recovery can be reliably increased. Moreover, overexpansion can be reliably prevented.

According to the second invention , the expander of the present invention is used to perform the expansion stroke of the vapor compression refrigeration cycle. Therefore, in the vapor compression refrigeration cycle, the operating conditions are likely to change, and the efficiency of power recovery in the expander tends to decrease when the expansion ratio is low, but the efficiency reduction can be effectively prevented.

According to the third invention , since the expander of the present invention is used for the supercritical cycle, the power loss in the supercritical cycle is particularly large, but the loss is more effectively suppressed. It becomes possible.

According to the fourth aspect of the present invention , in the expander equipped with a rotary expansion mechanism (60) represented by a swing piston type, a rolling piston type, or a scroll type, the rotation is suppressed by suppressing overexpansion. Power recovery efficiency can be increased.

According to the fifth aspect of the present invention , in the fluid machine having the positive displacement expander (60), the electric motor (40), and the compressor (50) in the casing (31), the recovered power of the expander (60) is obtained. Can be used together with the electric motor (40) for the driving power of the compressor (50), the power recovery efficiency of the expander (60) can be increased, so the driving input to the compressor (50) by the electric motor (40) can be suppressed, It becomes possible to operate efficiently.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Embodiment 1>
In the first embodiment, an air conditioner (10) is configured using the fluid machine of the present invention.

<Overall configuration of air conditioner>
As shown in FIG. 1, the air conditioner (10) is of a so-called separate type, and includes an outdoor unit (11) and an indoor unit (13). The outdoor unit (11) includes an outdoor fan (12), an outdoor heat exchanger (23), a first four-way switching valve (21), a second four-way switching valve (22), and a compression / expansion unit (30). Is stored. The indoor unit (13) houses an indoor fan (14) and an indoor heat exchanger (24). The outdoor unit (11) is installed outdoors, and the indoor unit (13) is installed indoors. The outdoor unit (11) and the indoor unit (13) are connected by a pair of connecting pipes (15, 16). Details of the compression / expansion unit (30) will be described later.

The air conditioner (10) is provided with a refrigerant circuit (20). The refrigerant circuit (20) is a closed circuit to which a compression / expansion unit (30), an indoor heat exchanger (24), and the like are connected. The refrigerant circuit (20) is filled with carbon dioxide (CO ₂ ) as a refrigerant.

  Both the outdoor heat exchanger (23) and the indoor heat exchanger (24) are cross fin type fin-and-tube heat exchangers. In the outdoor heat exchanger (23), the refrigerant circulating in the refrigerant circuit (20) exchanges heat with outdoor air. In the indoor heat exchanger (24), the refrigerant circulating in the refrigerant circuit (20) exchanges heat with room air.

  The first four-way selector valve (21) has four ports. The first four-way switching valve (21) has a first port connected to the discharge port (35) of the compression / expansion unit (30) and a second port connected to the interior via the connection pipe (15). One end of the heat exchanger (24) is piped, the third port is piped to one end of the outdoor heat exchanger (23), and the fourth port is the suction port (34) of the compression / expansion unit (30) And piping connected. The first four-way switching valve (21) is in a state where the first port and the second port communicate with each other and the third port and the fourth port communicate with each other (a state indicated by a solid line in FIG. 1). Then, the first port and the third port communicate with each other and the second port and the fourth port communicate with each other (state indicated by a broken line in FIG. 1).

  The second four-way selector valve (22) has four ports. The second four-way selector valve (22) has a first port connected to the outflow port (37) of the compression / expansion unit (30) and a second port other than the outdoor heat exchanger (23). The third port is connected to the other end of the indoor heat exchanger (24) via the connecting pipe (16), and the fourth port is connected to the inlet port (30) of the compression / expansion unit (30). 36) and pipe connected. The second four-way selector valve (22) is in a state where the first port and the second port communicate with each other and the third port and the fourth port communicate with each other (a state indicated by a solid line in FIG. 1). Then, the first port and the third port communicate with each other and the second port and the fourth port communicate with each other (state indicated by a broken line in FIG. 1).

<Configuration of compression / expansion unit>
As shown in FIG. 2, the compression / expansion unit (30) constitutes the fluid machine of the present invention. In this compression / expansion unit (30), a compression mechanism part (50), an expansion mechanism part (60), and an electric motor (40) are housed in a casing (31) which is a horizontally long and cylindrical sealed container. Yes. In the casing (31), the compression mechanism (50), the electric motor (40), and the expansion mechanism (60) are arranged in this order from left to right in FIG. Note that “right” and “left” used in the description with reference to FIG. 2 mean “right” and “left” in FIG.

  The said electric motor (40) is arrange | positioned in the center part of the longitudinal direction of a casing (31). The electric motor (40) includes a stator (41) and a rotor (42). The stator (41) is fixed to the casing (31). The rotor (42) is disposed inside the stator (41). The main shaft portion (48) of the shaft (45) passes through the rotor (42) coaxially with the rotor (42).

  The shaft (45) has a large-diameter eccentric part (46) formed on the right end side thereof and a small-diameter eccentric part (47) formed on the left end side thereof. The large-diameter eccentric part (46) is formed to have a larger diameter than the main shaft part (48), and is eccentric from the axis of the main shaft part (48) by a predetermined amount. On the other hand, the small-diameter eccentric portion (47) is formed with a smaller diameter than the main shaft portion (48), and is eccentric from the shaft center of the main shaft portion (48) by a predetermined amount. And this shaft (45) comprises the rotating shaft.

  Although not shown, an oil pump is connected to the shaft (45). Lubricating oil is stored at the bottom of the casing (31). This lubricating oil is pumped up by an oil pump, supplied to the compression mechanism (50) and the expansion mechanism (60), and used for lubrication.

  The said compression mechanism part (50) comprises what is called a scroll compressor. The compression mechanism (50) includes a fixed scroll (51), a movable scroll (54), and a frame (57). The compression mechanism (50) is provided with a suction port (34) and a discharge port (35).

  In the fixed scroll (51), a spiral fixed-side wrap (53) projects from the end plate (52). The end plate (52) of the fixed scroll (51) is fixed to the casing (31). On the other hand, in the movable scroll (54), a spiral movable side wrap (56) projects from a plate-shaped end plate (55). The fixed scroll (51) and the movable scroll (54) are disposed so as to face each other. The compression chamber (59) is defined by the meshing of the fixed wrap (53) and the movable wrap (56).

  One end of the suction port (34) is connected to the outer peripheral side of the fixed side wrap (53) and the movable side wrap (56). On the other hand, the discharge port (35) is connected to the center of the end plate (52) of the fixed scroll (51), and one end thereof opens to the compression chamber (59).

  The end plate (55) of the movable scroll (54) has a protruding portion formed at the center of the right side surface, and the small diameter eccentric portion (47) of the shaft (45) is inserted into the protruding portion. The movable scroll (54) is supported by the frame (57) via an Oldham ring (58). The Oldham ring (58) is for regulating the rotation of the movable scroll (54). The movable scroll (54) revolves at a predetermined turning radius without rotating. The turning radius of the movable scroll (54) is the same as the amount of eccentricity of the small diameter eccentric portion (47).

  The expansion mechanism section (60) is a so-called oscillating piston type expansion mechanism and constitutes a positive displacement expander of the present invention. The expansion mechanism (60) includes a cylinder (61), a front head (63), a rear head (64), and a piston (65). The expansion mechanism (60) is provided with an inflow port (36) and an outflow port (37).

  The cylinder (61) has its left end face closed by the front head (63) and its right end face closed by the rear head (64). That is, the front head (63) and the rear head (64) each constitute a closing member.

  The piston (65) is housed in a cylinder (61) whose both ends are closed by a front head (63) and a rear head (64). As shown in FIG. 4, the expansion chamber (62) is formed in the cylinder (61), and the outer peripheral surface of the piston (65) is substantially in sliding contact with the inner peripheral surface of the cylinder (61). It has become.

  As shown in FIG. 4A, the piston (65) is formed in an annular shape or a cylindrical shape. The inner diameter of the piston (65) is substantially equal to the outer diameter of the large-diameter eccentric part (46). The large-diameter eccentric portion (46) of the shaft (45) is provided so as to penetrate the piston (65), and the inner peripheral surface of the piston (65) and the outer peripheral surface of the large-diameter eccentric portion (46) are almost the entire surface. Slid over.

  The piston (65) is integrally provided with a blade (66). The blade (66) is formed in a plate shape and protrudes outward from the outer peripheral surface of the piston (65). The expansion chamber (62) sandwiched between the inner peripheral surface of the cylinder (61) and the outer peripheral surface of the piston (65) is divided into a high pressure side (suction / expansion side) and a low pressure side (discharge side) by the blade (66). Partitioned.

  The cylinder (61) is provided with a pair of bushes (67). Each bush (67) is formed in a half-moon shape. The bush (67) is installed with the blade (66) sandwiched therebetween, and slides with the blade (66). The bush (67) is rotatable with respect to the cylinder (61) with the blade (66) interposed therebetween.

  As shown in FIG. 4, the inflow port (36) is formed in the front head (63) and constitutes an introduction passage. The terminal end of the inflow port (36) opens at a position where the inflow port (36) does not directly communicate with the expansion chamber (62) on the inner surface of the front head (63). Specifically, the end of the inflow port (36) is the portion of the inner surface of the front head (63) that is in sliding contact with the end surface of the large-diameter eccentric portion (46), and the main shaft portion (48) in FIG. It opens at a slightly upper left position of the axis.

  A groove-like passage (69) is also formed in the front head (63). As shown in FIG. 4 (b), the groove-like passage (69) is formed in a concave groove shape opened on the inner surface of the front head (63) by digging the front head (63) from the inner surface. Has been.

  The opening portion of the groove-like passageway (69) on the inner side surface of the front head (63) has a rectangular shape that is elongated vertically in FIG. The groove-like passage (69) is located on the left side of the axis of the main shaft portion (48) in FIG. Further, the groove-like passage (69) has an upper end in the same figure (a) located slightly inside the inner peripheral surface of the cylinder (61) and a lower end in the same figure (a) as the front head (63). It is located in the part which slidably contacts with the end surface of a large diameter eccentric part (46) among the inner surfaces. The groove-like passage (69) can communicate with the expansion chamber (62).

  A communication path (70) is formed in the large-diameter eccentric part (46) of the shaft (45). As shown in FIG. 4 (b), the communication path (70) has a large diameter eccentric portion (46) facing the front head (63) by digging the large diameter eccentric portion (46) from the end face side. It is formed in the shape of a concave groove that opens to the end face.

  Moreover, as shown to Fig.4 (a), the communicating path (70) is formed in the circular arc shape extended along the outer periphery of a large diameter eccentric part (46). Furthermore, the center in the circumferential direction of the communication path (70) is a line connecting the axis of the main shaft (48) and the axis of the large-diameter eccentric portion (46), and the large-diameter eccentric portion (46). It is located on the opposite side of the shaft center of the main shaft portion (48) with respect to the shaft center. When the shaft (45) rotates, the communication path (70) of the large-diameter eccentric part (46) also moves accordingly, and the inflow port (36) and the groove-shaped path (69) are moved through this communication path (70). ) Intermittently communicate.

  As shown in FIG. 4A, the outflow port (37) is formed in the cylinder (61). The starting end of the outflow port (37) opens to the inner peripheral surface of the cylinder (61) facing the expansion chamber (62). Further, the starting end of the outflow port (37) is opened near the right side of the blade (66) in FIG.

  As a feature of the present invention, the expansion mechanism section (60) branches from the inflow port (36) on the fluid inflow side of the expansion chamber (62) to the suction / expansion process position of the expansion chamber (62). A communication pipe (72) is provided as a communication passage communicating with the. The communication pipe (72) is provided with a flow control mechanism (73) for switching the flow / stop of the refrigerant flowing through the communication pipe (72) and adjusting the flow rate.

  The connecting pipe (72) is connected to the vicinity of the left side of the blade (66) in FIG. Specifically, the connecting pipe (72) is counterclockwise in FIG. 4 (a) when the position of the rotation center of the bush (67) is 0 ° with respect to the rotation center of the shaft (45). At a position of about 20 ° to 30 °, the cylinder (61) is connected. The opening / closing mechanism (73) is constituted by an electric valve (injection valve) whose opening degree can be adjusted. By adjusting the opening degree of the motor-operated valve (73), it is possible to adjust the flow rate of the refrigerant flowing through the communication pipe (72). Further, when the motor-operated valve (73) is closed, the refrigerant can be prevented from flowing through the communication pipe (72).

  In the air conditioner (10) of the first embodiment, in addition to the high pressure sensor (74a) and the low pressure sensor (74b) that are generally provided in the refrigerant circuit (20), an excess pressure that detects the pressure in the expansion chamber (62) is detected. An expansion pressure sensor (74c) is provided. The control means (74) of the air conditioner (10) can control the motor-operated valve (73) based on the pressure detected by these sensors (74a, 74b, 74c).

-Driving action-
The operation of the air conditioner (10) will be described. Here, the operation during the cooling operation and the heating operation of the air conditioner (10) will be described, and then the operation of the expansion mechanism section (60) will be described.

《Cooling operation》
During the cooling operation, the first four-way switching valve (21) and the second four-way switching valve (22) are switched to the state indicated by the broken line in FIG. When the electric motor (40) of the compression / expansion unit (30) is energized in this state, the refrigerant circulates in the refrigerant circuit (20), and a vapor compression refrigeration cycle is performed.

  The refrigerant compressed by the compression mechanism (50) is discharged from the compression / expansion unit (30) through the discharge port (35). In this state, the refrigerant pressure is higher than the critical pressure. This discharged refrigerant is sent to the outdoor heat exchanger (23) through the first four-way switching valve (21). In the outdoor heat exchanger (23), the refrigerant flowing in exchanges heat with outdoor air sent by the outdoor fan (12). By this heat exchange, the refrigerant dissipates heat to the outdoor air.

  The refrigerant radiated by the outdoor heat exchanger (23) passes through the second four-way switching valve (22) and flows into the expansion mechanism (60) of the compression / expansion unit (30) through the inflow port (36). To do. In the expansion mechanism (60), the high-pressure refrigerant expands, and its internal energy is converted into rotational power of the shaft (45). The low-pressure refrigerant after expansion flows out from the compression / expansion unit (30) through the outflow port (37), passes through the second four-way switching valve (22), and is sent to the indoor heat exchanger (24).

  In the indoor heat exchanger (24), the refrigerant flowing in exchanges heat with the indoor air sent by the indoor fan (14). By this heat exchange, the refrigerant absorbs heat from the room air and evaporates, thereby cooling the room air. The low-pressure gas refrigerant coming out of the indoor heat exchanger (24) passes through the first four-way switching valve (21), passes through the suction port (34), and the compression mechanism (50) of the compression / expansion unit (30). Inhaled. The compression mechanism (50) compresses and discharges the sucked refrigerant.

《Heating operation》
During the heating operation, the first four-way switching valve (21) and the second four-way switching valve (22) are switched to the state shown by the solid line in FIG. When the electric motor (40) of the compression / expansion unit (30) is energized in this state, the refrigerant circulates in the refrigerant circuit (20), and a vapor compression refrigeration cycle is performed.

  The refrigerant compressed by the compression mechanism (50) is discharged from the compression / expansion unit (30) through the discharge port (35). In this state, the refrigerant pressure is higher than the critical pressure. The discharged refrigerant passes through the first four-way switching valve (21) and is sent to the indoor heat exchanger (24). In the indoor heat exchanger (24), the refrigerant flowing in exchanges heat with room air. By this heat exchange, the refrigerant dissipates heat to the room air, and the room air is heated.

  The refrigerant radiated by the indoor heat exchanger (24) passes through the second four-way switching valve (22) and flows into the expansion mechanism (60) of the compression / expansion unit (30) through the inflow port (36). To do. In the expansion mechanism (60), the high-pressure refrigerant expands, and its internal energy is converted into rotational power of the shaft (45). The low-pressure refrigerant after expansion flows out from the compression / expansion unit (30) through the outflow port (37), passes through the second four-way switching valve (22), and is sent to the outdoor heat exchanger (23).

  In the outdoor heat exchanger (23), the refrigerant flowing in exchanges heat with the outdoor air, and the refrigerant absorbs heat from the outdoor air and evaporates. The low-pressure gas refrigerant discharged from the outdoor heat exchanger (23) passes through the first four-way switching valve (21), passes through the suction port (34), and the compression mechanism (50) of the compression / expansion unit (30). Inhaled. The compression mechanism (50) compresses and discharges the sucked refrigerant.

<Operation of expansion mechanism>
The operation of the expansion mechanism section (60) will be described with reference to FIGS. FIG. 3 shows a cross section of the expansion mechanism portion (60) perpendicular to the central axis of the large-diameter eccentric portion (46) at every rotation angle of 45 ° of the shaft (45). 4 to 11, (a) is an enlarged view of the cross section of the expansion mechanism (60) for each rotation angle in FIG. 3, and (b) is a large-diameter eccentric part (46). 2 schematically shows a cross section of the expansion mechanism section (60) along the central axis. 4 to 11, the cross section of the main shaft portion (48) is not shown in (b).

  When high-pressure refrigerant is introduced into the expansion chamber (62), the shaft (45) rotates counterclockwise in each of FIGS.

  When the rotation angle of the shaft (45) is 0 °, the end of the inflow port (36) is covered with the end face of the large-diameter eccentric part (46) as shown in FIGS. That is, the inflow port (36) is closed by the large-diameter eccentric portion (46). The communication path (70) of the large-diameter eccentric part (46) communicates only with the groove-shaped path (69). The groove-like passage (69) is covered with the end face of the piston (65) and the large-diameter eccentric portion (46), and is not in communication with the expansion chamber (62). The expansion chamber (62) is communicated with the outflow port (37), so that the whole is on the low pressure side. At this time, the expansion chamber (62) is in a state of being blocked from the inflow port (36), and the high-pressure refrigerant does not flow into the expansion chamber (62).

  When the rotation angle of the shaft (45) is 45 °, the inflow port (36) communicates with the communication path (70) of the large-diameter eccentric part (46) as shown in FIGS. The communication path (70) also communicates with the groove-shaped path (69). The groove-like passage (69) is in a state in which the upper end portion in FIG. 3 or FIG. At this point, the expansion chamber (62) is in communication with the inflow port (36) via the communication passage (70) and the groove-like passage (69), and the high-pressure refrigerant is in the high pressure of the expansion chamber (62). To the side. In other words, the introduction of the high-pressure refrigerant into the expansion chamber (62) is started when the rotation angle of the shaft (45) reaches 0 ° to 45 °.

  When the rotation angle of the shaft (45) is 90 °, as shown in FIGS. 3 and 6, the expansion chamber (62) still remains in the inflow port (70) and the groove-like passage (69) through the inflow port (70). 36). Therefore, the high-pressure refrigerant continues to flow into the high-pressure side of the expansion chamber (62) until the rotation angle of the shaft (45) reaches 45 ° to 90 °.

  When the rotation angle of the shaft (45) is 135 °, as shown in FIGS. 3 and 7, the communication path (70) of the large-diameter eccentric part (46) becomes the groove-shaped path (69) and the inflow port (36). It will be in a state that is out of both. At this time, the expansion chamber (62) is in a state of being blocked from the inflow port (36), and the high-pressure refrigerant does not flow into the expansion chamber (62). Therefore, the introduction of the high-pressure refrigerant into the expansion chamber (62) is completed until the rotation angle of the shaft (45) reaches 90 ° to 135 °.

  After the introduction of the high-pressure refrigerant into the expansion chamber (62) is completed, the high-pressure side of the expansion chamber (62) becomes a closed space, and the refrigerant flowing into the expansion chamber (62) expands. That is, as shown in FIGS. 3 and 8 to 11, the shaft (45) rotates and the volume on the high pressure side in the expansion chamber (62) increases. Meanwhile, the low-pressure refrigerant after expansion continues to be discharged through the outflow port (37) from the low pressure side of the expansion chamber (62) communicating with the outflow port (37).

  The expansion of the refrigerant in the expansion chamber (62) is such that the contact portion of the piston (65) with the cylinder (61) is in the outflow port (37) during the rotation angle of the shaft (45) from 315 ° to 360 °. Continue until you reach. When the portion of the piston (65) that contacts the cylinder (61) crosses the outflow port (37), the expansion chamber (62) is communicated with the outflow port (37), and the discharge of the expanded refrigerant is started.

  Here, when the ideal operation of the refrigeration cycle is performed and no excessive expansion occurs in the expansion chamber (62), the motor-operated valve (73) is closed. At this time, the relationship between the volume change of the expansion chamber (62) and the pressure change is as shown in the graph of FIG. That is, after the high-pressure fluid is supplied into the expansion chamber (62) from the point a to the point b, the expansion starts from the point b. In the expansion chamber (62), when the introduction of the high-pressure fluid stops, the pressure once suddenly drops to the point c, and the pressure gradually decreases to the point d due to the subsequent expansion. Then, after the discharge process is performed in the expansion chamber (62), the process returns to the point a and the next suction process is started. At this time, the density ratio between the intake refrigerant and the exhaust refrigerant is the design expansion ratio, and operation with good power recovery efficiency is performed.

  On the other hand, in the refrigerant circuit (20), the high pressure and the low pressure may deviate from the design pressure due to switching between the cooling operation and the heating operation or a change in the outside air temperature. In such a case, the control means (74) performs the following operation control based on the pressure detected by the sensors (74a, 74b, 74c).

  For example, the actual expansion ratio may be smaller than the design expansion ratio because the low-pressure pressure increases due to a change in operating conditions. Under such conditions, the amount of refrigerant discharged from the compression mechanism section (50) at the same rotational speed generally increases, while the expansion mechanism section (60) flows at substantially the same amount of refrigerant at the same rotational speed. The refrigerant quantity of the expansion mechanism part (60) is smaller than the refrigerant quantity from the mechanism part (50). In this embodiment, in such a case, if the opening degree of the motor-operated valve (73) is adjusted, an amount of refrigerant necessary for the motor-operated valve (73) can always be introduced into the expansion mechanism section (60). (50) and the expansion mechanism (60) can be adjusted to have the same flow rate. By doing so, the efficiency has been lowered by the refrigerant that does not perform the expansion work by bypassing the expansion mechanism section (60) in the past, but the operation efficiency can be improved.

  FIG. 15 shows an operation state in which the opening degree of the electric valve (73) is adjusted. In this case, the refrigerant gradually expands to the point d ′ after completing the suction process from the point a to the point b ′. The refrigerant is further discharged to the point e ', and then the next suction process is started in the expansion chamber (62). In this operating state, since the expansion work is performed in the area I surrounded by the points a, b ', d', and e ', efficient operation can be performed.

  Further, in the first embodiment, the low pressure is increased so that the actual expansion ratio becomes smaller than the design expansion ratio, and overexpansion is prevented even under the condition that the expansion chamber (62) is at a lower pressure than the outflow port (37). can do. That is, when the condition for causing overexpansion in the expansion chamber (62) is reached, the motor-operated valve (73) is opened to a predetermined opening, and a part of the high-pressure refrigerant is introduced into the expansion chamber (62) from the connecting pipe (72). Thereby, the pressure of an expansion chamber (62) can be raised to the low pressure of a refrigerating cycle, and overexpansion can be eliminated. Therefore, when the motor-operated valve (73) is not provided, the power is consumed in the area II indicating the overexpansion region in FIG. 13, and the power recovery efficiency of the expansion mechanism section (60) is greatly reduced. As shown in FIG. 15, the power consumption shown in the area II of FIG. 13 is not performed. Therefore, it is possible to prevent the recovery efficiency from being reduced by the area II.

-Effect of Embodiment 1-
As described above, according to the first embodiment, the expansion chamber (62) branches from the inflow port (37) on the fluid inflow side and communicates with the position in the suction / expansion process of the expansion chamber (62). A connecting pipe (72) that adjusts the opening of the motorized valve (73) under operating conditions with a small expansion ratio so that the flow rate of the compressor (50) and the flow rate of the expander (60) can be the same. Yes. This makes it possible to recover power in the expander (60) even under conditions where the expander (60) has been bypassed by the refrigerant in the past, and an efficient operation can be performed.

  In the first embodiment, the motor-operated valve (73) can be opened and the connecting pipe (72) can be opened under conditions where overexpansion occurs. Therefore, the state of overexpansion is increased by increasing the pressure in the expansion chamber (62). Can be resolved. Therefore, power is not consumed to discharge the refrigerant under conditions where overexpansion occurs, and power recovery efficiency by the expansion mechanism section (60) is improved. And since power recovery efficiency improves, it becomes possible to suppress useless input to a compression mechanism part (50), and to perform efficient driving | operation.

  Further, in the above configuration, the connecting pipe (72) is connected to the expansion chamber (62), and among the positions in the suction / expansion process, in particular, the initial position of the process (the rotation angle of the shaft (45) is about 20 ° to about 20 °). 30 ° position), in the operating conditions where it is necessary to introduce the high-pressure refrigerant into the expansion chamber (62), a part of the high-pressure refrigerant is put into the expansion chamber (62) during the suction / expansion process. Can be introduced almost always.

Further, in Embodiment 1, in a vapor compression refrigeration cycle that is performed by compressing carbon dioxide (CO ₂ ) that is a refrigerant to a supercritical state, for example, when the cooling operation is performed when the design is based on the heating operation. While over-expansion tends to occur, the occurrence of over-expansion can be effectively prevented.

< Embodiment 2 of the Invention>
Embodiment 2 of the present invention is obtained by changing the configuration of the expansion mechanism (60) in the first embodiment. Specifically, the expansion mechanism part (60) of the first embodiment is configured as a swinging piston type, whereas the expansion mechanism part (60) of the present embodiment is configured as a rolling piston type. . Here, the difference from the first embodiment will be described regarding the expansion mechanism section (60) of the present embodiment.

As shown in FIG. 16 , in this embodiment, the blade (66) is formed separately from the piston (65). That is, the piston (65) of this embodiment is formed in a simple annular shape or a cylindrical shape. Further, a blade groove (68) is formed in the cylinder (61) of the present embodiment.

The blade (66) is provided in the blade groove (68) of the cylinder (61) so as to freely advance and retract. The blade (66) is urged by a spring (not shown), and the tip (lower end in FIG. 16 ) is pressed against the outer peripheral surface of the piston (65). As shown in FIG. 17 , even if the piston (65) moves in the cylinder (61), the blade (66) moves up and down in the figure along the blade groove (68). It is kept in contact with the piston (65). The expansion chamber (62) is partitioned into a high pressure side and a low pressure side by pressing the tip of the blade (66) against the peripheral side surface of the piston (65).

Also in the second embodiment , the inflow port (36) and the position of the expansion chamber (62) in the suction / expansion process are connected by the connecting pipe (72), and the motor-operated valve (73) is connected to the connecting pipe (72). Is provided. Therefore, a part of the refrigerant on the inflow port (36) side can be supplementarily introduced into the expansion chamber (62) under the low expansion ratio condition, so that the power recovery efficiency can be improved and the overexpansion can be performed as in the above embodiments. Can also be eliminated.

<Other Embodiments of Invention>
The present invention may be configured as follows with respect to the above embodiment.

For example, in the first embodiment , the example in which the inflow port (36) is formed on the front head (63) side of the expansion mechanism (60) has been described. However, the inflow port (36) is provided on the rear head (64) side. Also good. In this embodiment, in order to introduce the high-pressure refrigerant into the expansion chamber (62), the communication path (70) on the end surface of the large-diameter eccentric part (46) provided in the shaft (45), and the front head (63) The inflow port (36) and the expansion chamber (62) are communicated with each other via a groove-like passage (69) provided on the inner surface, but such a configuration may be changed as appropriate.

  In each of the above-described embodiments, the example in which the present invention is applied to the swing piston type expansion mechanism and the rolling piston type expansion mechanism has been described. However, the present invention can also be applied to a scroll type expansion mechanism.

  In the above embodiments, the compression / expansion unit (30) including the expansion mechanism (60), the compression mechanism (50), and the electric motor (40) in one casing (31) has been described. The present invention may be applied to an expander formed separately from the compressor.

  In short, in the present invention, a communication passage (72) branched from the fluid inflow side of the expansion mechanism (60) and communicating with the suction / expansion process position of the expansion chamber (62) is provided. Other configurations may be appropriately changed as long as the configuration can be opened under conditions.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a positive displacement expander including an expansion mechanism that generates power when a high-pressure fluid expands, and a fluid machine including the expander.

It is a piping system diagram of the air conditioner in Embodiment 1. 2 is a schematic cross-sectional view of a compression / expansion unit according to Embodiment 1. FIG. It is a schematic sectional drawing which shows operation | movement of an expansion mechanism part. It is a schematic sectional drawing which shows the principal part of the expansion mechanism part in Embodiment 1 in the rotation angle 0 degree or 360 degrees of a shaft. It is a schematic sectional drawing which shows the principal part of the expansion mechanism part in Embodiment 1 in the rotation angle of 45 degrees of a shaft. It is a schematic sectional drawing which shows the principal part of the expansion mechanism part in Embodiment 1 in the rotation angle of 90 degrees of a shaft. It is a schematic sectional drawing which shows the principal part of the expansion mechanism part in Embodiment 1 in the rotation angle 135 degrees of a shaft. It is a schematic sectional drawing which shows the principal part of the expansion mechanism part in Embodiment 1 in the rotation angle of a shaft of 180 degrees. It is a schematic sectional drawing which shows the principal part of the expansion mechanism part in Embodiment 1 in the rotation angle of 225 degrees of a shaft. It is a schematic sectional drawing which shows the principal part of the expansion mechanism part in Embodiment 1 in the rotation angle of 270 degrees of a shaft. It is a schematic sectional drawing which shows the principal part of the expansion mechanism part in Embodiment 1 in the rotation angle of 315 degrees of a shaft. It is a graph which shows the relationship between the volume of an expansion chamber and the pressure on the driving | running condition at design pressure. It is a graph which shows the relationship between the volume of an expansion chamber and pressure under low expansion ratio conditions. It is a 1st graph which shows the relationship between the volume of an expansion chamber at the time of a low expansion ratio countermeasure, and a pressure. It is a 2nd graph which shows the relationship between the volume of an expansion chamber at the time of a low expansion ratio countermeasure, and a pressure. 6 is a schematic cross-sectional view showing a main part of an expansion mechanism in Embodiment 2. FIG. It is a schematic sectional drawing which shows operation | movement of an expansion mechanism part.

10 Air conditioner
20 Refrigerant circuit
30 Compression / expansion unit (fluid machinery)
31 Casing
40 electric motor
50 compressor
60 Expansion mechanism (positive displacement expander)
61 Cylinder (component)
62 Expansion chamber
72 Connection pipe (communication passage)
73 Motorized valve (distribution control mechanism)

Claims (8)

A positive displacement expander including an expansion mechanism (60) that generates power by expanding a high-pressure fluid supplied to an expansion chamber (62),
A communication passage (72) branched from the fluid inflow side of the expansion chamber (62) and communicating with an initial position of the expansion / expansion process of the expansion chamber (62);
A positive displacement expander characterized in that a flow control mechanism (73, 75, 76) is provided in the communication passage (72). The positive displacement expander according to claim 1,
A positive displacement expander characterized in that the flow control mechanism (73, 75, 76) includes an injection valve (73) whose opening degree can be adjusted. The positive displacement expander according to claim 1,
The positive displacement expander characterized in that the flow control mechanism (73, 75, 76) is configured by an electromagnetic valve (75) that can be opened and closed. The positive displacement expander according to claim 1,
The flow control mechanism (73, 75, 76) is composed of a differential pressure valve (76) that opens when the fluid pressure at the intermediate position of the expansion chamber (62) falls below a predetermined value with respect to the pressure on the fluid outflow side. A positive displacement expander characterized by being made. The positive displacement expander according to any one of claims 1 to 4,
A positive displacement expander characterized in that the expansion mechanism (60) is configured to perform an expansion stroke of a vapor compression refrigeration cycle. The positive displacement expander according to any one of claims 1 to 4,
The expansion mechanism (60) is configured to perform an expansion stroke of a vapor compression refrigeration cycle in which a high pressure becomes a supercritical pressure. The positive displacement expander according to any one of claims 1 to 6,
The expansion mechanism (60) is a rotary expansion mechanism,
A positive displacement expander configured to recover rotational power by expansion of a fluid. In the casing (31), a positive displacement expander (60), an electric motor (40), and a compressor (50) driven by the positive displacement expander (60) and the electric motor (40) to compress fluid. A fluid machine comprising:
8. A fluid machine, wherein the positive displacement expander (60) comprises the positive displacement expander according to claim 7.

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