JP4709076B2 - Positive displacement fluid machine - Google Patents

Description

  The present invention relates to a positive displacement fluid machine, and more particularly, to a fluid machine having a function of expanding and compressing a refrigerant in a refrigeration cycle.

  2. Description of the Related Art Conventionally, for example, a fluid machine including an expander unit and a compressor unit is known as a fluid machine used by being connected to a refrigeration cycle.

  For example, a rolling piston type expander unit and a compressor unit are housed in the same container, and the main shafts of the expander unit and the compressor unit are connected coaxially so that the expansion energy of the refrigerant flowing into the expander unit A technique is disclosed in which the main shaft is rotationally driven by using this to drive the compressor unit (see Patent Document 1).

  Thus, COP of a refrigerating cycle can be improved by collect | recovering motive power in the expansion | swelling process of a refrigerating cycle, and utilizing for a compression process.

JP-A-8-82296

  By the way, the fluid machine of Patent Document 1 is configured such that an auxiliary motor is installed between the expander unit and the compressor unit, and the main shafts of the auxiliary motor, the expander unit, and the compressor unit are connected to each other. These main shafts are provided with a phase difference so that the rotational position of the expander unit when the maximum torque is generated coincides with the rotational position of the compressor unit when the maximum load torque is generated.

  As described above, in Patent Document 1, since the rotational torque is applied from the auxiliary motor to the main shaft when the fluid machine is activated, the activation torque of the fluid machine can be sufficiently ensured.

  However, in the case where the auxiliary motor is housed in the container in this way, there is a problem that the structure of the fluid machine becomes complicated, for example, the manufacturing cost becomes expensive and the apparatus itself becomes large.

  On the other hand, in the case of a fluid machine that does not include a power source such as an auxiliary motor, a starting torque larger than the load torque (static friction force) of the expander unit and the compressor unit may be generated from the expander unit. If not, the fluid machine cannot be started.

  An object of the present invention is to realize stable start-up without using an auxiliary motor in a fluid machine having an expander section and a compressor section.

  In the fluid machine of the present invention, the expander unit and the compressor unit are housed in a container, the fluid flowing into the expander unit is expanded to drive the expander unit, and the compressor unit is driven by the driving force. Is.

  Here, each of the expander sections is formed by a spiral blade formed upright on a plate material, and meshes with each other to form a plurality of working chambers, a fixed scroll and a turning scroll, and a fluid flow opening at a central portion of the fixed scroll. The scroll expander unit includes an inlet, a fluid discharge port that opens to the outer periphery of the fixed scroll, and a first eccentric shaft unit that is connected to the orbiting scroll. The compressor unit includes a cylinder, A closing plate that closes both ends of the cylinder, a cylindrical roller that rotates eccentrically inside the cylinder, and a vane portion that is in contact with the outer peripheral surface of the roller and partitions the space formed by the cylinder, the roller, and the closing plate, It is assumed that this is a rolling piston type compressor portion that includes a spring that urges the vane portion and presses it against the roller, and a second eccentric shaft portion that is connected to the roller.

  For example, when the compressor is started by connecting the expander portion of the fluid machine to the downstream side of the compressor of the refrigeration cycle, the high-pressure refrigerant passes through the central inlet of the fixed scroll and is located at the innermost periphery. Flows into the working chamber. At this time, since the working chamber on the discharge port side of the expander section is at a lower pressure than the working chamber on the inlet side, the orbiting scroll acts as a radial force from the center of rotation of the main shaft due to this pressure difference, and generates rotational torque. appear.

  Here, in the working chamber communicating with the inflow port, the radial force due to the refrigerant works most effectively when the volume is maximum. However, the volume of the working chamber changes with the revolution of the orbiting scroll, and decreases rapidly immediately after the volume reaches the maximum. For this reason, the rotational position of the orbiting scroll is set to a rotational position where the volume of the working chamber communicating with the inflow port is maximized. In this case, a maximum or near rotational torque can be generated.

  On the other hand, the compressor unit is connected, for example, between the discharge port side of the expander unit and the suction port side of the compressor. For this reason, in the compressor section, the working chamber on the discharge port side has a lower pressure than the working chamber on the suction port side partitioned by the vanes in the cylinder. That is, the refrigerant that has flowed into the cylinder from the suction port moves the roller to a position where the working chamber on the suction port side has the maximum volume due to the pressure difference between the working chambers, and at this time, generates rotational torque on the main shaft. The starting torque generated from the expander unit and the compressor unit has the same rotational direction.

  Therefore, by providing a predetermined phase difference between the first eccentric shaft portion of the expander portion and the second eccentric shaft portion of the compressor portion, it is possible to simultaneously extract the starting torque from the expander portion and the compressor portion. However, in order to rotate the main shaft by this starting torque, it is necessary that the orbiting scroll and the roller be stationary at a position where these starting torques always exceed the load torque (static frictional force) of the expander unit and the compressor unit. .

  Therefore, in the present invention, attention is paid to the fact that the roller in the compressor portion is always stationary at the rotational position where the total length of the spring is maximized by the pressing force of the vane portion, and the rotational position of the roller when the spring is extended to the maximum. The rotation position of the orbiting scroll is limited to the rotation position where the volume of the working chamber communicating with the inlet is maximized, and the first eccentric shaft portion and the second rotation portion are in a range of −45 degrees from this rotation position. It is characterized by providing a phase difference with the eccentric shaft portion.

  According to this, since the rotational positions of the first eccentric shaft portion and the second eccentric shaft portion can be made substantially the same when the fluid machine is stopped, it is generated from the expander portion and the compressor portion at the time of startup. The starting torque to be obtained can be taken out almost as a maximum, and stable starting can be realized without using an auxiliary motor.

  In addition, the fluid machine of the present invention can realize a significant improvement in COP by, for example, recovering the power of the expansion process when the working refrigerant of the refrigeration cycle is carbon dioxide.

  ADVANTAGE OF THE INVENTION According to this invention, the stable starting can be implement | achieved without using an auxiliary motor in the fluid machine which has an expander part and a compressor part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a fluid machine to which the present invention is applied. FIG. 2 is a schematic diagram of a refrigeration cycle provided with a fluid machine to which the present invention is applied. FIG. 3 is a Mollier diagram of a refrigeration cycle provided with a fluid machine to which the present invention is applied. FIG. 4 is a cross-sectional view of an expander unit and a compressor unit of a fluid machine to which the present invention is applied. FIG. 5 is an operation diagram of the expander unit and the compressor unit for each crank angle of the fluid machine to which the present invention is applied.

  The refrigeration cycle of the present embodiment uses carbon dioxide (R744) as a working fluid (hereinafter abbreviated as a refrigerant as appropriate). Carbon dioxide (R744) as a refrigerant has a global warming potential (GWP) as small as one thousandth of that of CFC refrigerants, and is excellent in terms of global environmental conservation. On the other hand, although the theoretical COP (coefficient of performance) on the Mollier diagram of the high-pressure refrigerant is low, R744 recovers the power of the expansion process because the energy loss of the expansion process is larger than that of the chlorofluorocarbon refrigerant. By doing so, the COP can be greatly improved.

  The fluid machine of the present embodiment houses a scroll type expander unit 1 and a rolling piston type compressor unit 3 in the same sealed container 9, and the expander unit 1 and the compressor unit 3 are driven by each. By connecting the shafts (main shafts) coaxially, the power generated when the refrigerant expands in the expander unit 1 is recovered to drive the compressor unit 3 so that the compressor / compressor performs compression work. Yes.

  The expander unit 1 has a fixed scroll 5 and a orbiting scroll 7 that are each formed by allowing a spiral wrap to stand upright on a disc-shaped end plate, and is arranged in a posture facing each other, and bites the fixed scroll 5 and the orbiting scroll 7. By combining them, a plurality of working chambers are formed between them. The fixed scroll 5 is fixed to a frame 11 fixed to the sealed container 9.

  An inflow pipe 15 is formed in the suction port 13 that opens in the center of the fixed scroll 5, while an outflow pipe 19 is formed in the discharge port 17 that opens in the outer periphery of the fixed scroll 5. The orbiting scroll 7 is formed with a bearing 23 at the center of the surface opposite to the wrap. An expander eccentric shaft 21a connected to one end of a crankshaft 21 rotatable about the central axis L1 is slidably fitted to the bearing 23, and the orbiting scroll 7 is supported by the expander eccentric shaft 21a. As a result, the orbiting scroll 7 revolves with a predetermined eccentric amount about the central axis L1 with respect to the fixed scroll 5, moves the working chamber to the outer peripheral side, and expands the volume of the working chamber. The orbiting scroll 7 is restricted from revolving motion by the Oldham ring 25.

  The compressor unit 3 includes a cylinder 31 having a cylindrical inner peripheral surface, end plates 27 and frames 11 that close both end surfaces of the cylinder 31, a cylindrical roller 33 that performs eccentric rotational movement in the cylinder 31, and a roller 33. A plate-like vane 35 that reciprocates in a groove 37 formed in the cylinder 31 while contacting an end face with the outer peripheral surface of the cylinder, and divides a space formed by the cylinder 31 and the roller 33 into a suction chamber 39 and a compression chamber 41. And a spring 43 that is installed at the rear end of the vane 35 and presses the vane 35 against the outer peripheral surface of the roller 33. Further, a compressor eccentric shaft 21b connected to the other end of the crankshaft 21 is rotatably fitted to the roller 33.

  A suction port 45 and a discharge port 47 for the refrigerant are formed in the cylinder 31, and a suction pipe 49 is formed in the suction port 45, while a discharge valve 51 and a discharge pipe 53 are connected to the discharge port 47. .

  As described above, the orbiting scroll 7 of the expander unit 1 and the roller 33 of the compressor unit 3 are connected at a predetermined rotation angle by the expander eccentric shaft 21a, the compressor eccentric shaft 21b, and the crankshaft 21.

  Next, the operation when the working fluid flows into the fluid machine will be described.

  First, when a high-pressure working fluid flows into the working chamber formed in the innermost periphery through the inflow pipe 15 of the expander unit 1, the orbiting scroll 7 revolves around the central axis L1 due to the decompression and expansion of the working fluid. The revolving motion of the orbiting scroll 7 moves the working chamber to the outer peripheral side while expanding the volume, and flows out from the outflow pipe 19 in a decompressed state. Further, when the orbiting scroll 7 revolves, the crankshaft 21 having the expander eccentric shaft 21a as one end rotates.

  On the other hand, in the compressor section 3 arranged on the other end side of the crankshaft 21, when the crankshaft 21 is rotated by the expander section 1, the roller 33 rotates eccentrically in the cylinder 31 via the compressor eccentric shaft 21b. . With the eccentric rotation of the roller 33, the vane 35 reciprocates in the groove 37 while being pressed against the outer peripheral surface of the roller 33 by the spring 43.

  The volumes of the two working chambers partitioned by the vanes 35 in the cylinder 31, that is, the suction chamber 39 and the compression chamber 41 change with the eccentric rotation of the roller 33. When a low-pressure working fluid is sucked into the suction chamber 39 through the suction pipe 49, the suction chamber 39 is compressed to a predetermined pressure as the volume decreases. The compressed working fluid is discharged from the discharge pipe 53 to the outside through the discharge valve 51.

  The fluid machine according to the present embodiment drives the compressor unit 3 using expansion energy generated when the working fluid expands in the expander unit 1, and compresses the working fluid in the driven compressor unit 3. The working fluid can be expanded and compressed without using the above.

  Next, the configuration and operation of the refrigeration cycle including the fluid machine will be described with reference to FIGS.

  The refrigeration cycle of the present embodiment is configured by connecting a compressor 61, a radiator (gas cooler) 63, a fluid machine 65, an evaporator 67, and an expansion valve 69 with refrigerant pipes. The compression device 61 is configured by housing a main compressor 71 and an electric motor 73 in a sealed container. In the fluid machine 65, an evaporator 67 is connected between the expander unit 1 and the compressor unit 3 (also referred to as a sub-compressor). The expansion valve 69 is disposed in a bypass path that bypasses a path connecting the expander unit 1 and the evaporator 67. The expansion valve 69 is closed except for adjusting the flow rate (pressure) when the operating conditions of the cycle change.

  The high-temperature / high-pressure refrigerant compressed in the main compressor 71 (the state at point C in FIG. 3) is discharged from the discharge port of the compressor 61, passes through the radiator 63, and is reduced in temperature by heat dissipation (FIG. 3). Point D) and enters the expander section 1 of the fluid machine 65 through the inflow pipe 15. The refrigerant that has flowed into the expander unit 1 converts expansion energy into mechanical energy during the expansion process to drive the compressor unit 3, and the low-temperature and low-pressure gas-liquid two-phase refrigerant (point E in FIG. 3) from the outflow pipe 19. And discharged.

  The refrigerant discharged from the expander unit 1 enters the evaporator 67 and is gasified by heat absorption, and is then sucked into the compressor unit 3 of the fluid machine 65 through the suction pipe 49 (point A in FIG. 3). The refrigerant flowing into the compressor unit 3 is slightly pressurized and discharged through the discharge pipe 53 (point B in FIG. 3). The gas refrigerant discharged from the compressor unit 3 is returned to the main compressor 71 and compressed again to become a high-temperature and high-pressure gas refrigerant. The above cycle is repeated to produce a freezing action.

  As described above, when the fluid machine 65 of the present embodiment is used in a refrigeration cycle, the expansion energy of the expander unit 1 is recovered as power, and the recovered power is used as a drive source of the compressor unit 3 in the compression process. Therefore, the amount of work in the main compressor 71 can be reduced and the COP of the refrigeration cycle can be improved.

  In the present embodiment, carbon dioxide is used as the refrigerant in the refrigeration cycle. However, even in the case of the fluorocarbon refrigerant, the COP can be improved, although not as much as the improvement ratio of carbon dioxide.

  Next, the operation at the start of the refrigeration cycle will be described in detail.

  Immediately before the start of the refrigeration cycle, the pressure in the cycle is a substantially constant balance pressure, and the operation of the main compressor 71 is started from this pressure balanced state to start the refrigeration cycle.

  First, the expansion valve 69 is closed simultaneously with the start of operation of the main compressor 71. As a result, the suction side pressure of the main compressor 71 decreases and the discharge side pressure increases as the rotational speed of the main compressor 71 increases. Then, the high-pressure refrigerant whose pressure has increased passes through the radiator 63 and reaches the innermost working chamber (71 in FIG. 4) of the expander unit 1 through the inflow pipe 15. At this time, since the working chamber around the innermost working chamber is maintained at the balance pressure at the time of stopping, the radial force with respect to the central axis L1 of the crankshaft 21 is exerted on the orbiting scroll 7 by the pressure difference between the working chambers. Occurs and rotational torque is generated.

  When the rotational torque at the time of starting (starting torque) exceeds the static frictional force at the sliding portions of the expander unit 1 and the compressor unit 3 of the fluid machine 65, the crankshaft 21 starts to rotate. Here, the size of the working chamber is determined according to the rotational position of the orbiting scroll 7 at rest, and in particular, the innermost working chamber 71 communicating with the suction port 13 is applied in the radial direction of the refrigerant as its volume increases. The force increases and as a result, the starting torque increases. For this reason, the innermost working chamber 71 communicates with the suction port 13 and generates a starting torque sufficient to exceed the static frictional force of each sliding portion, so that a predetermined volume is ensured when stationary. Need to be.

  On the other hand, when the suction side pressure of the main compressor 71 decreases, the pressure in the compression chamber 41 of the compressor unit 3 of the fluid machine 65 and the space communicating with the compression chamber 41 decreases. At this time, since the suction chamber 39 of the compressor unit 3 is maintained at the balance pressure at the time of stop, a pressure difference is generated between the working chambers of the suction chamber 39 and the compression chamber 41. Due to this pressure difference, the roller 33 moves to the rotational position where the volume of the suction chamber 39 is maximized, and at the same time, rotational torque is generated in the crankshaft 21. Since the direction in which this rotational torque is applied is the same as the rotational direction of the expander unit 1, the rotational torque when the fluid machine 65 is started increases.

  Thus, the fluid machine 65 of the present refrigeration cycle generates start-up torque from each of the expander unit 1 and the compressor unit 3 if the orbiting scroll 7 and the roller 33 are stopped at a predetermined rotational position at the time of start-up. To do. That is, when the fluid machine 65 is stopped, it is necessary to always keep the orbiting scroll 7 and the roller 33 stationary at a position where the starting torque exceeds the static frictional force in preparation for the next starting. Therefore, in this embodiment, in order to define the rotation angle between the expander unit 1 and the compressor unit 3, the rotation of the expander eccentric shaft 21 a and the compressor eccentric shaft 21 b with respect to the central axis L 1 of the crankshaft 21. Specifies the phase.

  Here, paying attention to the compressor unit 3 when the fluid machine 65 is stopped, the roller 33 of the compressor unit 3 always receives the pressing force of the spring 43 via the vane 35. For this reason, when the fluid machine 65 stops, the roller 33 moves to a rotational position (vane bottom dead center) where the total length of the spring is maximum by the pressing of the spring 43 and stops. That is, the roller 33 stops at a position where the suction chamber 39 and the compression chamber 41 have substantially the same volume. For this reason, when the roller 33 starts the refrigeration cycle from the position of the vane bottom dead center, the pressure on the discharge side of the compressor unit 3 is reduced, creating a pressure difference between the suction chamber 39 and the compression chamber 41, and the roller 33. Since the suction chamber 39 moves to the rotational position where the volume of the suction chamber 39 is maximized, the starting torque can be obtained when the roller 33 moves.

  From the above, in this embodiment, when the compressor unit 3 is at the rotational position of the roller 33 at the vane bottom dead center, the rotation of the orbiting scroll 7 so that the rotational torque generated by the expander unit 1 is maximized. Specifically, the rotational position of the expander eccentric shaft 21a is determined so that the volume of the innermost working chamber 71 communicating with the inlet of the expander unit 1 is maximized. .

  FIG. 5 shows an example of the relationship between the orbiting scroll 7 for each crank angle, the vane position, and the starting torque. In the expander unit 1, the starting torque increases as the volume of the innermost working chamber 71 communicating with the suction port 13 increases. Is larger and the fluid machine is easier to start. Therefore, in the fluid machine of the present embodiment, the crank angle when the volume of the innermost working chamber 71 communicating with the suction port 13 of the expander unit 1 is maximized and the vane bottom dead center of the compressor unit 3 are obtained. The expander eccentric shaft 21a and the compressor eccentric shaft 21b are arranged at a predetermined phase with respect to the central axis L1 of the crankshaft 21 so that the crank angle at the same time coincides. As a result, the orbiting scroll 7 always stops at the rotational position where the volume of the innermost working chamber 71 communicating with the suction port 13 is maximized when the fluid machine 65 is stopped, and after the main compressor 71 is started, the suction port 13 is stopped. Thus, the high-pressure refrigerant flows into the innermost working chamber that communicates with each other, and the maximum starting torque that can be generated by the expander unit 1 can be obtained.

  In general, the innermost working chamber 71 of the scroll expander section continuously increases in volume from the start of communicating with the suction port 13 until the working chamber is completely closed, but the working chamber is completely closed. Immediately after that, the innermost working chamber is further moved to the working chamber formed on the inner circumferential side, so that the volume is rapidly reduced. For this reason, if the rotational position of the orbiting scroll 7 at the time of stopping deviates from the position where the spring length is maximum due to the pressing of the roller 33, there is a possibility that the operating chamber is in a state immediately after it is closed. In this case, the starting torque generated by the expander unit 1 is the smallest, and there is a possibility that the fluid machine cannot be driven.

  In order to prevent this, the rotational position (crank angle) when the orbiting scroll 7 is stopped should be shifted slightly forward from the rotational position at which the working chamber is closed. For example, with respect to the vane bottom dead center, The expander eccentric shaft 21a is preferably arranged in an angle range from this rotation position to -45 degrees, with the rotation position where the volume of the working chamber communicating with the suction port 13 of the expander unit 1 is maximized as a limit. Thereby, even if the rotation position of the crankshaft 21 at the time of a stop shift | deviates from a vane bottom dead center, the fall of starting torque can be prevented and stable starting can be performed.

  As described above, according to the fluid machine of the present embodiment, the expander unit 1 includes the scroll type expander, the compressor unit 3 includes the rolling piston type rotary compressor, and the roller 33 of the rolling piston type compressor unit. Is urged by the spring 43 via the vane 35 so that the rotational position of the crankshaft 21 at the time of stopping can be made substantially the same, and the starting torque generated by the expander unit 1 at the rotational position. Therefore, for example, stable start-up can be realized without installing an auxiliary motor, reliability of the refrigeration cycle can be improved, and efficient expansion energy recovery can be realized. Moreover, since it is not necessary to provide a starting means such as an auxiliary motor in the fluid machine, it is possible to contribute to the cost reduction of the equipment.

It is sectional drawing of the fluid machine formed by applying this invention. It is a schematic diagram of the refrigerating cycle provided with the fluid machine to which this invention is applied. It is a Mollier diagram of a refrigeration cycle provided with a fluid machine to which the present invention is applied. It is a cross-sectional view of an expander part and a compressor part of a fluid machine to which the present invention is applied. It is an operation | movement diagram of the expander part and compressor part for every crank angle of the fluid machine to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Expander part 3 Compressor part 5 Fixed scroll 7 Orbiting scroll 13 Suction port 21 Crankshaft 21a Expander eccentric shaft 21a
21b Compressor eccentric shaft 21b
31 Cylinder 33 Roller 35 Vane 43 Spring

Claims (3)

An expander unit and a compressor unit are accommodated in a container, a fluid is expanded by the expander unit to drive the expander unit, and the compressor unit is driven by a driving force of the expander unit. In fluid machinery,
The expander section includes a fixed scroll and an orbiting scroll, each of which has a spiral blade formed upright on a plate material and meshes with each other to form a plurality of working chambers. A scroll-type expander unit including an inlet, a discharge port of the fluid that opens to an outer peripheral portion of the fixed scroll, and a first eccentric shaft unit that is connected to the orbiting scroll;
The compressor section includes a cylinder, a closing plate that closes both ends of the cylinder, a cylindrical roller that rotates eccentrically inside the cylinder, and the cylinder, the roller, and the blocking that are in contact with the outer peripheral surface of the roller. A rolling piston type compressor section comprising a vane section that partitions a space formed by a plate, a spring that urges the vane section to press it against the roller, and a second eccentric shaft section that is coupled to the roller. Yes,
The first eccentric shaft portion and the second eccentric shaft portion are connected to a main shaft, and the rotational position of the orbiting scroll communicates with the inflow port with respect to the rotational position of the roller when the spring is most extended. Between the first eccentric shaft portion and the second eccentric shaft portion so that the rotational position where the volume of the working chamber is maximized is within a range of −45 degrees from the rotational position. A positive displacement fluid machine characterized by providing a phase difference. The phase difference between the first eccentric shaft portion and the second eccentric shaft portion is such that the rotational position of the orbiting scroll communicates with the inflow port with respect to the rotational position of the roller when the spring is most extended. The positive displacement fluid machine according to claim 1, wherein the displacement chamber is set so as to be a rotational position where the volume of the working chamber is maximized. The positive displacement fluid machine according to claim 1, wherein the fluid is carbon dioxide.

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