Patent Publication Number: US-2010107669-A1

Title: Three-way solenoid valve, rotary compressor, and refrigeration cycle equipment

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a Continuation Application of PCT Application No. PCT/JP2008/062831, filed Jul. 16, 2008, which was published under PCT Article 21(2) in Japanese. 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2007-186231, filed Jul. 17, 2007, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a three-way solenoid valve which selects one of fluids flowing in from two directions, and leads the selected fluid to a predetermined direction, a two-cylinder rotary compressor which adopts the three-way solenoid valve, and refrigeration cycle equipment which includes the rotary compressor for constituting a refrigeration cycle. 
     2. Description of the Related Art 
     A document 1 (Japanese Patent No. 2002-181210) discloses a three-way solenoid valve for low-pressure water, which is used for supplying low-pressure water equivalent to tap water to an ice tray of a refrigerator. The valve is configured to hold a diaphragm attached closely to a valve body shaft by a body which contains first and second valve seats, and a guide in which one end of the valve body shaft is inserted, so that controlled fluid is prevented from residing or flowing out from the body into the guide, even if the valve body shaft is moved. 
     A document 2 (Jpn. UM Appln. KOKAI Publication No. 3-19175) discloses a three-way motor valve, which is used as a promotional control valve in a refrigeration cycle of a refrigerator or air conditioner. The valve is configured to energize a coil to rotate a rotor provided in a case, and to move a valve body in upward or downward. The valve body is configured to control a flow rate by changing the aperture areas of a valve seat formed in the lower end portion of a chamber, and a valve seat formed in the upper end portion of another chamber. 
     BRIEF SUMMARY OF THE INVENTION 
     The three-way solenoid valve for low-pressure water disclosed in the document 1 adopts a method of directly sliding a valve body by a magnetic force. Therefore, a holding spring force greater than fluid pressure is required, and greater magnetic force is required for switching a high-pressure fluid. This is unsuitable for switching a high-pressure fluid. 
     The three-way solenoid valve for a high-pressure refrigerant disclosed in the document 2 requires a driving torque greater than fluid pressure, and slides a valve body by rotating a shaft by a pulse motor, to maintain sealing between a valve body and a valve seal. Therefore, the structure is complex, the control is complicated, and the size is inevitably increased. 
     The invention has been made in the above circumstances. Accordingly, it is an object of the invention to provide a three-way solenoid valve, which is configured to slide a valve body by a magnetic force, usable for a high-pressure fluid, simple in structure, and improves reliability; a rotary compressor which adopts the three-way solenoid valve in the refrigerant injection side of a two-cylinder compression mechanism; and refrigeration cycle equipment which includes the rotary compressor for constituting a refrigeration cycle. 
     In order to achieve the above object, a three-way solenoid valve according to the invention is configured to have a cylindrical valve box in which a first valve seat is provided at one end, an outflow port is opened, and a second valve seat is provided at a position apart in an axial direction from the first valve seat; a valve body which is provided movably back and forth in the valve box, and has an internal flow path whose one end is opened in the end face of the outflow port, and the other end is opened on the side; a solenoid unit which is located at the other end of the valve box, and has a plunger provided as a single unit with the valve body, and drives the valve body together with the plunger; a sealing means which seals the space between the valve box and valve body, and divides the internal space of the valve box into a first chamber opposing the first valve seat, and a second chamber opposing the second valve seat; and a first inflow port which is provided in the first chamber, and is opened in the direction substantially orthogonal to the axis line of the valve box, and a second inflow port which is provided in the second chamber, and is opened in the direction substantially orthogonal to the axis line of the valve box, wherein the first inflow port communicates with the outflow port when the valve body contacts the second valve seat, and the second inflow port communicates with the outflow port through the internal flow path of the valve body when the valve body contacts the first valve seat. 
     In order to achieve the above object, a rotary compressor comprises a sealed case which contains an electric motor unit, a first compression mechanism connected to the electric motor unit, and a second compression mechanism configured to apply back pressure to a vane by internal pressure of the case; and a switching means which is provided in a gas suction path connected to a cylinder chamber of the second compression mechanism, and is configured to switch connection of the cylinder chamber to a low-pressure side of a refrigeration cycle or a high-pressure side of a refrigeration cycle including a space inside the sealed case, and to lead a low-pressure refrigerant into the cylinder chamber to perform normal compression, or to lead a high-pressure refrigerant into the cylinder chamber to perform idle operation, wherein the switching means comprises the three-way solenoid valve according to aforementioned description, connects an outflow port of the three-way solenoid valve to the downstream of the gas suction path connected to the cylinder chamber of the second compression mechanism, connects one of the first inflow port and second inflow port to the upstream of the gas suction path, and connects the other ends of the first inflow port and second inflow port to the high-pressure side of the refrigeration cycle. 
     In order to achieve the above object, refrigeration cycle equipment according to the invention comprises the rotary compressor, a condenser, an expansion unit, and an evaporator. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  is a schematic sectional view of a three-way solenoid valve according to an embodiment of the invention, in normal operation mode; 
         FIG. 2  is a schematic longitudinal sectional view of a three-way solenoid valve according to the embodiment, in special operation mode; 
         FIG. 3  is an explanatory diagram explaining the flow of magnetic flux in a solenoid unit in a three-way solenoid valve according to an embodiment of the invention; 
         FIG. 4  shows a configuration of a refrigeration cycle which adopts a three-way solenoid valve according to the embodiment in a rotary compressor; and 
         FIG. 5  is an explanatory diagram explaining a configuration structure of a three-way solenoid valve according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the invention will be explained hereinafter based on the accompanying drawings. 
       FIG. 1  is a longitudinal sectional view of a three-way solenoid valve V in normal operation mode to be described later.  FIG. 2  is a longitudinal sectional view of the three-way solenoid valve V in special operation mode to be described later. 
     A reference number  1  in the drawings denotes a cylindrical valve box. In the lower end portion of the valve box in the drawings, an outflow port  2  is opened, and connected to an outflow tube  2 P. A first valve seat  3  is provided along the outflow port  2  inside the valve box  1 . An insertion hole  4  is provided in the upper end portion of the valve box  1 . A second valve seat  5  is provided along the insertion hole  4  inside the valve box  1 . Therefore, the second valve seat  5  is provided in the upper position apart from the first valve seat  3  in the axial direction. The valve box  1  may be molded in a single piece, or formed as a single piece from two or more members. 
     In the upper part where the insertion hole  4  of the valve box  1  is provided, a guide unit  7  is extended as one body through a step portion  6  having a reduced diameter. The guide unit  7  is formed cylindrical with a diameter reduced to smaller than the part where the first and second valve seats  3  and  5  are provided, and its upper end is closed. A solenoid unit  8  to be described later is provided along the outer circumference of the guide unit  7 . The solenoid unit  8  is located above the valve box  1 . 
     In the valve box  1 , a valve body  10  is housed movably back and forth along the axial direction. The valve body  10  is shaped in the form of a deformed cylinder, in which a first opening  11   a  is provided in the end portion of the outflow port  2  that is the lower end, and a second opening  11   b  is provided on the side of the upper end. Therefore, the valve body  10  has an internal flow path  11  which communicates a first opening  11   a  with a second opening  11   b.    
     The internal flow path  11  is L-shaped in  FIG. 1 . It may be T-shaped, or may be a hole inclined along the axis line of the valve body  10 , as long as one end is opened to the end portion of the outflow port  2 , and the other end is opened to the side. 
     In the valve body  10 , a first valve unit  12  is provided along the peripheral edge of the first opening  11   a , and a second valve unit  13  is provided along the lower peripheral edge of the second opening  11   b . In  FIG. 1 , the first and second valve units  12  and  13  are made in the form of a circular ring projecting to the outer circumference of the valve body  10 , but they are not limited to a projected circular ring. 
     The valve body  10  A is provided with a columnar plunger  10 A as a single unit. The plunger  10 A is extended upward from the second opening  11   b  provided in the upper part of the valve body  10 . The extended part includes a flange-shaped backup plate  14  with a diameter slightly smaller than the internal diameter of the guide unit  7 . 
     Therefore, the plunger  10 A including the backup plate  14  is housed movably in the guide unit  7 . The part of the plunger  10 A under the backup plate  14  can be inserted into the valve box  1  through the insertion hole  4 . 
     The solenoid unit  8  located on the outer periphery of the valve box  1  is configured to move up and down the valve  10  and plunger  10 A, and constitutes a self-holding coil. 
     Further, an outer yoke  15  is fitted to the outer periphery downward from the upper end of the upper guide unit  7 , with a predetermined clearance to the guide unit  7 . A coil  16  is wound around the periphery of the outer yoke  15 , and is held by a holding member  17 . 
     A washer  18  is fitted in the step portion  6  that forms a boundary between the valve box  1  and guide unit  7 , and a permanent magnet  19  is inserted between the washer  18  and outer yoke  15 . The washer  18  side of the permanent magnet  19  is the north pole, and the outer yoke  15  side is the south pole. 
     A tube cap  20  is fitted inside the upper closed end part of the guide unit  7 . A columnar part that tightly contacts the upper closed end part of the tube cap  20  is formed as one body with a cylinder unit in which a part of the upper end of the plunger  10 A is movably fitted, forming a reversed-concave cross section. 
     A compression spring  22  is inserted between the lower end of the tube cap  20  and the backup plate  14  of the guide unit. In other words, a clearance is provided between the lower end of the tube cap  20  and the backup plate  14  of the guide unit, even if the valve body  10  is positioned at the uppermost part of the valve box  1  as shown in  FIG. 1 . The compression spring  22  inserted into the clearance always elastically presses and energizes the valve body  10  that is movable to the fixed tube cap  20 , in the direction of the outflow port  2  that is a lower part. 
     Explaining again the valve box  1 , an intermediate part between the first valve seat  3  and second valve seat  5  provided in the valve box  1  is opened, and a circular sealing projection (a sealing means)  23  is provided inside the opening. The circular sealing projection  23  is projected to the axis line of the valve box  1 , forming a sealing surface on the upper surface, lower surface, and inside surface. 
     The distance between the circular sealing projection  23  and first valve seat  3  in the valve box  1  coincides with the distance between the first valve unit  12  and second valve unit  13  in the valve body  10 . The distance between the circular sealing projection  23  and second valve seat  5  is designed to coincide with the distance between the first valve unit  12  and second valve unit  13 . 
     As described later, in the state in which the solenoid unit  8  is energized or not energized, the valve body  10  is moved up and down, and one of the first valve seat  12  and second valve seat  13  contacts the circular sealing projection  23 . In other words, the first valve seat  12  or second valve seat  13  of the valve body  10  contacts the circular sealing projection  23 , and completely seals the space between the inside surface of the valve box  1  and the outside surface of the valve body  10 . 
     As the valve units  12  and  13  of the valve body  10  contact the circular sealing projection  23 , the inside space of the valve box  1  forms a first chamber M 1  by opposing the first valve seat  3 , and forms a second chamber M 2  by opposing the second valve seat  5 . In other words, the first and second chambers M 1  and M 2  are divided to upper and lower parts by the circular sealing projection  23 . 
     In the first chamber M 1 , the outflow port  2  that is connected to the outflow tube  2 P is provided along the axial direction of the valve box  1 . In the first chamber M 1 , a first inflow port  25  is opened in the direction orthogonal to the direction of axis, and is connected to a first inflow tube  25 P. In the second chamber M 2 , a second inflow port  26  is opened in the direction orthogonal to the direction of axis of the valve box  1 , and is connected to a second inflow tube  26 P. 
     A means of sealing the inside space of the valve box  1  is not limited to the circular sealing projection  23  inside the valve box. It is permitted to forma circular projection, which forms a surface to seal the inner circumference of the valve body  10 , or to provide a separately-formed sealing member between the outer surface of the valve body and the inner surface of the valve box. 
     Next, the function of the three-way solenoid valve V will be explained. 
       FIG. 1  shows normal operation mode of the three-way solenoid valve, in which a magnetic force is generated by energizing the solenoid unit  8 , and the plunger  10 A and valve body  10  are raised against the electric force of the compression spring  22 .  FIG. 2  shows special operation mode, in which the solenoid unit  8  is not energized, the solenoid unit  8  does not generate a magnetic force, and the elastic force of the compression spring  22  acts on the plunger  10 A, and moves down the valve body  10 . In either state, a magnetic flux is always generated in a permanent magnet  19  provided in the solenoid unit  8 . 
     First, the state of  FIG. 1  is explained in detail. Magnetic force is generated by energizing the solenoid unit  8 . As a result, the valve body  10  is raised against the elastic force of the compression spring, and positioned in the second chamber M 2 . The valve unit  13  of the valve body  10  contacts the valve seat  5  of the valve box  1 , the first valve unit  12  contacts the circular sealing projection  23 , and seals the space between them. Therefore, the second inflow port  26  is closed by the valve body  10 . 
     In other words, the valve body  10  does not present in the first chamber M 1 , and the first inflow port  25  and outflow port  2  are kept open. Even if high-pressure fluid is led from both first inflow tube  25 P connected to the first inflow port  25  and the second inflow tube  26 P connected to the second inflow port  26 , as the second inflow port  26  is closed by the valve body  10 , the high pressure of the fluid flowing from the second inflow tube  26 P to the three-way solenoid valve V is cancelled. 
     The high-pressure fluid flowing from the first inflow tube  25 P is led into the three-way solenoid valve V through the first inflow port  25 , and then led to the inflow tube  2 P through the inflow port  2 . In this manner, the three-way solenoid valve V selects the high-pressure fluid led from the inflow tube  25 P, leads it to the inflow tube  2 P, and cancels against the second inflow tube  26 P. 
     The pressure of the high-pressure fluid flowing in the three-way solenoid valve V is received by the valve body  10 , and pressed and energized upward in the drawing. The second valve unit  13  of the valve body  10  contacts more closely the second valve seat  5  of the valve box  1 , and the first valve unit  12  of the valve body  10  contacts more closely the circular sealing projection  23 . The above function makes sealing of the valve body  10  to the valve box  1  more complete. 
     Further, as described later, the magnetic force of the permanent magnet  19  in the solenoid unit  8  has an influence in the direction of raising the plunger  10 A. Thus, similar to the high-pressure fluid led into the valve box, the second valve unit  13  contacts more closely the second valve  5 , and the first valve unit  12  contacts more closely the circular sealing projection  23 , thereby making the sealing of the valve body  10  to the valve box  1  more complete. 
     As shown in  FIG. 2 , in special operation mode, the solenoid unit  8  is not energized, and magnetic force is not generated. The elastic force of the compression spring  22  is restored, and acts on the plunger  10 A, whereby the valve body  10  is moved down, and shifted from the second chamber M 2  to the first Chamber M 1 . 
     The first valve unit  12  at the lower end of the valve body  10  contacts the first valve seat  3  of the valve box  1 , and the upper second valve  13  contacts the circular sealing projection  23 , making respective sealing. Therefore, the first inflow port  25  is completely closed by the valve body  10 . 
     The first opening  11   a  of the valve body  10  is located at the same position as the outflow port  2 , and communicates with the outflow port. The second opening  11   b  of the valve body  10  opposes the second inflow port  26 , and communicates with the second inflow port. Therefore, the internal flow path  11  of the valve body  10  communicates with the second inflow port  26  and outflow port  2 . 
     In the above state, high-pressure fluid is led from both first inflow tube  25 P connected to the first inflow port  25  and the second inflow tube  26 P connected to the second inflow port  26 . As the first inflow port  25  is being closed by the valve body  10 , the high pressure of the fluid flowing from the first inflow tube  25 P to the three-way solenoid valve V is cancelled. 
     The high-pressure fluid flowing from the second inflow tube  26 P is led to the inside of the three-way solenoid valve V through the second inflow port  26 , and is further led to the first opening  11   a  from the second opening  11   b  of the valve body  10  through the internal fluid path  11 . As the first opening  11   a  communicates with the outflow port  2 , the high-pressure fluid flowing out of the internal fluid path  11  is led to the outflow tube  2 P through the outflow port  2 . 
     The pressure of the high-pressure fluid led from the second inflow port  26  into the valve box is received by the valve body  10 , and pressed and energized downward in the drawing. The first valve unit  12  of the valve body  10  contacts more closely the first valve seat  3  of the valve box  1 , and the second valve unit  13  contacts more closely the circular sealing projection  23 . The above function makes the sealing of the valve body  10  to the valve box  1  more complete. 
     The permanent magnet  19  in the solenoid unit  8  has an influence on the magnetic force in the direction of raising the plunger  10 A, contrarily to the compression spring  22 , but the permanent magnet force is smaller than the elastic energizing force of the compression spring  22 , and does not affect the function of the compression spring  22 . 
     Next, an explanation will be given of the flow of magnetic flux in the solenoid unit  8 , based on modes A to D shown in  FIG. 3 .  FIG. 3  is a schematic explanatory diagram showing the flow of magnetic flux in the solenoid unit. 
     In the solenoid unit  8 , the plunger  10 A and tube cap  20  are located along the axis line as described above. A coil  16 , an outer yoke  15 , a permanent magnet  19 , and a washer  18  are provided around the outer periphery of the plunger. 
     When the coil  16  is energized, a magnetic circuit that flows a magnetic flux is sequentially generated in the outer yoke  15 , permanent magnet  19 , washer  18 , plunger  10 A, tube cap  20 , and outer yoke  15 . 
     In mode A in  FIG. 3 , the coil  16  is being not energized, and a magnetic flux Za of the permanent magnet  19  is being generated, but not so strong to move (actuate) the plunger  10 A. This is the normal OFF state. 
     At this time, the elastic force of the compression spring  22  is being applied to the plunger  10 A, one end of the plunger  10 A is separated from the tube cap  20 , and the other end the plunger  10 A is projected from the washer  18 . In other words, this state corresponds to the special operation explained in  FIG. 2 , in which the valve body  10  formed as one body with the plunger  10 A closes the first inflow port  25  in the first chamber M 1 , and the second inflow port  26  communicates with the outflow port  2  through the internal flow path  11  of the valve body  10 . 
     Next, in mode B in  FIG. 3 , the coil  16  is energized, and a magnetic flux Zb is generated in the outer yoke  15 . At this time, the coil  16  is set to positive (+) and negative (−), so that the magnetic flux Zb, which is the same direction as the magnetic flux Za that is always generated by the permanent magnet  19  in the direction (counterclockwise) indicated in the drawing, is generated in the outer yoke  15 . 
     An ON operation is performed by the above, and the magnetic flux Za that is usually generated by the permanent magnet  19  is combined with the magnetic flux Zb that is generated in the outer yoke  15  by energizing, in the same direction (counterclockwise). As a result, the combined magnetic fluxes Za and Zb act on the plunger  10 A as a magnetic force larger than the elastic energizing force of the compression spring  22 . 
     The plunger  10 A is moved to the right in the drawing against the elastic force of the compression spring  22 , and is finally absorbed by the tube cap  20 . As in the normal operation mode explained in  FIG. 1 , the valve body closes the second chamber M 2  by the movement of the plunger  10 A, and the first inflow port  25  communicates with the outflow port  2 . 
     After the plunger  10 A is moved, power supply to the coil  22  is stopped in mode C in  FIG. 3 . The operation goes into the OFF state, in which the magnetic flux Zb of the outer yoke  15  is lost, and only the magnetic flux Za of the permanent magnet  19  is kept. 
     By the magnetic flux Za of the permanent magnet  19 , the attractive forces of the magnetic poles formed in the end faces of the plunger  10 A and tube cap  20  (north pole in the plunger  10 A, and south pole in the tube cap  20 ) maintain the absorbed state (ON state) against the elastic force of the compression spring  22 . In other words, even if the solenoid unit  8  is deenergized after once energized, the magnetic flux Za of the permanent magnet  19  maintains the positions of the plunger  10 A and valve body  10 , and the normal operation state shown in  FIG. 1  is continued. 
     To stop normal operation, an OFF operation is executed for the solenoid unit  8 . At this time, the coil  16  is energized, but the polarities (+) and (−) are reversed to the state explained in mode B. The direction of the magnetic flow Za in the permanent magnet  19  is unchanged, but the direction of the magnetic flux Zb generated in the outer yoke  15  is reversed. 
     The permanent magnet  19  cancels the magnetic poles formed in the end faces of the plunger  10 A and tube cap  20 , and the magnetic attractive force is lost. Receiving the elastic force of the compression spring  22 , the plunger  10 A is moved and energized in the direction of separating from the tube cap  20 . In this state, power supply to the solenoid unit  8  is stopped. 
     Finally, the operation returns to the normal OFF state, mode A in  FIG. 3 . In this OFF state, the spring load and permanent magnet strength are set to the degree at which the plunger  10 A is not moved by the magnetic attractive force. 
     When the coil  16  is energized to execute the ON operation in mode B, a momentarily large current (magnetomotive force) is required to magnetically absorb the plunger  10 A. Thus, though indicated by a thick line, the OFF operation in mode D is executed for the purpose of canceling the magnetic force of the permanent magnet  19 , a required current is small, and this operation is indicated by a thin line. 
       FIG. 4  shows a schematic block diagram of a rotary compressor R which constitutes refrigeration cycle equipment X by using the three-way solenoid valve V in a two-cylinder rotary compressor R, and a configuration of a refrigeration cycle of the refrigeration cycle equipment X. (To simplify the drawing, some parts are not shown, or not given reference numbers, though they are explained.) 
     First, an explanation will be given of a configuration of a refrigeration cycle of the refrigeration cycle equipment X. R denotes a rotary compressor. A refrigerant discharge tube  30  is connected to the upper surface of the rotary compressor. The refrigerant discharge tube  30  is sequentially connected to a condenser  31 , an expansion unit  32 , an evaporator  33 , and an accumulator  34 . 
     A first refrigerant suction tube  30 P and a second refrigerant suction tube  25 Pa to be described are extended from the bottom of the accumulator  34 . Particularly, the second refrigerant suction tube  25 Pa is provided with the three-way solenoid valve V, and is connected to the rotary compressor R through a suction tube  2 Pa. 
     In the rotary compressor R, K denotes a sealed case. The sealed case K contains an electric motor unit  35 , and a first compressor mechanism  37  and a second compressor mechanism  38 , which are connected to the electric motor unit  35  through an axis of rotation  36 . 
     In addition to the first and second compression mechanisms  37  and  38 , rollers  41   a  and  41   b  are housed concentrically and rotatably in cylinder chambers  40   a  and  40   b  provided in cylinders  39   a  and  39   b . The inner surfaces of the rollers  41   a  and  41   b  are fitted to an eccentric part provided eccentrically in the axis of rotation  36 , and the outer surfaces receive back pressure and contact the distal end portions of vanes  42   a  and  42   b  (or may not contact as described later). 
     In the state in which, the distal end portions of the vanes  42   a  and  42   b  contact the rollers  41   a  and  41   b , the vanes  42   a  and  42   b  divide the cylinder chambers  40   a  and  40   b  into two chambers. A suction port is provided in one of the chambers, and a discharge port is provided in the other chamber. The first refrigerant suction tube  302  communicates with the suction port provided in the cylinder  39   a  of the first compression mechanism  37 . 
     The suction tube  2 Pa communicates with the suction port provided in the cylinder  39   b  of the second compression mechanism  38 . The discharge port communicates with the inside of the sealed case K directly or through guide paths provided in the cylinders  39   a  and  39   b.    
     The vane  42   a  used in the first compression mechanism  37  is housed in the vane chamber  43   a , and is configured to receive back pressure by a spring  44  provided between the rear end portion of the vane  42   a  and the rear wall of the vane chamber  43   a . The vane  42   b  used in the second compression mechanism  38  is housed in the vane chamber  43   b , but the vane chamber  43   b  is exposed to the inside of the sealed case K, and nothing directly contacts the rear end portion of the vane  42   b.    
     Concerning the vane  42   b  used in the second compression mechanism  38 , as the vane chamber  43   b  is exposed to the inside of the sealed case K, the pressure in the sealed case K influences the vane chamber  43   b , and acts as back pressure to the rear end portion of the vane  42   b.    
     The first refrigerant suction tube  30 P extended from the bottom of the accumulator  34  is connected to the cylinder  39   a  that constitutes the first compression mechanism  37 , penetrating through the sealed case K, and communicates with the suction port provided there. 
     The suction tube  2 Pa, which is communicating with the second refrigerant suction tube  25 Pa and three-way solenoid valve V, is connected to the cylinder  39   b  that constitutes the second compression mechanism  38 , penetrating through the sealed case K, and communicates with the suction port provided there. 
     A branch refrigerant discharge tube  26 Pa is connected to a mid-portion of the refrigerant discharge tube  30  which connects the sealed case K to the condenser  31 . The branch refrigerant discharge tube  26 Pa is connected to the three-way solenoid valve V. In such a configuration, the three-way solenoid valve V constitutes a switching means as described later. 
     Further, in the three-way solenoid valve V explained in  FIGS. 1 and 2 , instead of the first inflow tube  25 P connected to the first inflow port  25  provided in the valve box  1 , the second refrigerant suction tube  25 Pa extended from the bottom of the accumulator  34  is connected. 
     Instead of the second inflow tube  26 P connected to the second inflow port  26 , the branch refrigerant discharge tube  26 Pa branched from the refrigerant discharge tube  30  is connected. Instead of the outflow tube  2 P connected to the outflow port  2 , the suction tube  2 Pa that is communicating with the suction port of the cylinder  39   b  in the second compression mechanism  38  is connected. 
     In the normal operation state as explained in  FIG. 1 , the first inflow Sport  25  communicates with the outflow port  2  in the three-way solenoid valve V. Thus, in the configuration shown  FIG. 4 , the second refrigerant suction tube  25 Pa from the accumulator  34  communicates with the suction tube  2 Pa connected to the suction port of the cylinder  39   b  of the second compression mechanism  38 , through the three-way solenoid valve V. 
     In the special operation state as explained in  FIG. 2 , the second inflow port  26  communicates with the outflow port  2  in the three-way solenoid valve V. Thus, in the configuration shown  FIG. 4 , the branch refrigerant discharge tube  26 Pa branched from the refrigerant discharge tube  30  of the sealed case K communicates with the suction tube  2 Pa connected to the suction port of the cylinder  39   b  of the second compression mechanism  38 , through the three-way solenoid valve V. 
     In particular, applying the normal operation explained in  FIG. 1  to the configuration of  FIG. 4 , a low-pressure refrigerant is led from the accumulator  34  to the cylinder chamber  40   b  of the second compression mechanism  38 , through the three-way solenoid valve V. Applying the special operation explained in  FIG. 2  to the configuration of  FIG. 4 , a high-pressure refrigerant immediately after being discharged is led from the sealed case K to the cylinder chamber  40   b  of the second compression mechanism  38 , through the three-way solenoid valve V. 
     Next, an explanation will be given of the functions of the rotary compressor R and refrigeration cycle equipment X. 
     In normal operation, the electric motor unit  35  eccentrically rotates and drives the roller  41   a  of the first compression mechanism  37 , and eccentrically rotates and drives the roller  41   b  of the second compression mechanism  38 . In the first compression mechanism  37 , the vane  42   a  receives back pressure by the spring  44 , and divides the cylinder chamber  40   a  into a suction chamber and a compression chamber. 
     A low-pressure refrigerant is led from the accumulator  34  to the suction chamber through the first refrigerant suction tube  30 P, and compressed by the eccentric rotation of the roller  41   a . When the compressed refrigerant reaches a predetermined high pressure, it is discharged from the cylinder chamber  40   a  into the sealed case K, and filled in the sealed case K, making the inside of the case K high-pressure atmosphere. 
     On the other hand, a low-pressure refrigerant is led from the accumulator  34  to the cylinder chamber  40   b  of the second compression mechanism  38  through the second refrigerant suction tube  25 Pa, three-way solenoid valve V, and suction tube  2 Pa. The vane chamber  43   b  is exposed to the inside of the sealed case K, and is influenced by the pressure in the sealed case K. 
     In other words, in the second compression mechanism  38 , a low-pressure refrigerant is led to the cylinder chamber  40   b , and the distal end of the vane  42   b  is under low-pressure environment. On the other hand, the vane chamber  43   b  in which the rear end portion of the vane  42   b  is positioned is under high-pressure environment that is the pressure atmosphere of the sealed case K. A pressure difference is generated between the distal end portion and rear end portion of the vane  42   b , and the vane  42   b  receives back pressure equivalent to the pressure difference. 
     The vane  42   b  of the second compression mechanism  38  receives back pressure equivalent to a pressure difference between the inside of the sealed case K and the cylinder chamber  40   b , instead of the spring  44  which applies back pressure to the vane  42   a  of the first compression mechanism  37 . 
     The distal end of the vane  42   b  follows the eccentric rotation of the roller  41   b , always contacts the peripheral surface of the roller, and divides the cylinder chamber  40   b  into a suction chamber and a compression chamber. Finally, the second compression mechanism  38  performs the same compression as the first compression mechanism  37  does, and full-capacity operation is performed, in which a refrigerant is simultaneously compressed in two cylinder chambers  40   a  and  40   b.    
     Further, by using full-capacity operation at startup of operation, a stable operation is achieved in a short time. At this time, the three-way solenoid valve V is switched as described above, so that the branch refrigerant discharge tube  26 Pa communicates with the suction tube  2 Pa that is communicating with the cylinder chamber  40   b  in the second compression mechanism  38 . 
     As the spring  44  continuously applies back pressure to the vane  42   a  in the first compression mechanism  37 , a normal compression operation is performed, and a high-pressure refrigerant gas is discharged to the inside of the sealed case K. By switching the three-way solenoid valve V, the high-pressure refrigerant gas discharged from the sealed case K is directly led to the cylinder chamber  40   b  of the second compression mechanism  38  through the branch refrigerant discharge tube  26 Pa. 
     The cylinder chamber  40   b  of the second compression mechanism  38  becomes high-pressure atmosphere, as in the sealed case K and vane chamber  43   b . The distal end portion and rear end portion of the vane  42   be  become the same high-pressure state, and no pressure difference is generated. Thus, once the vane  42   b  is pushed back by the eccentric rotation of the roller  41   b , and it maintains the position. 
     Since the distal end of the vane  42   b  does not contact the peripheral surface of the roller  41   b , the cylinder chamber  40   b  is not divided into a suction chamber and a compression chamber, and the roller  41   b  simply continues an idle operation. In the rotary compressor R, the first compression mechanism  37  compresses a refrigerant, but the second compression mechanism  38  does not compress a refrigerant (a non-compression operation), and a compression capacity is reduced by half, that is special operation. 
     By using the three-way solenoid valve V as a switching means as described above, the operation can be easily and securely switched from full-capacity normal operation to half-capacity special operation. 
     The applicant discloses a rotary compressor and refrigeration cycle equipment, which are designed based on the same spirit and characteristics, in a document 3 (Japanese Patent No. 2004-301114). 
     As a means of switching from full-capacity operation to half-capacity operation, the document explains use of one of combination of a two-way valve and check valve, a three-way switching valve, and a four-way switching valve used in ordinary heat pump refrigeration cycle equipment. 
     However, the number of parts is increased in the combination of a two-way valve and check valve. A four-way switching valve cannot be used without modification, and needs to close one piping connection port, requiring time and labor. 
     Therefore, the three-way solenoid valve V explained hereinbefore is used as a three-way switching valve. This prevents increase in the number of parts, saves time and labor, and improves the workability in manufacturing and assembling. 
     As long as the setting of the suction tube  2 Pa, which communicates with the suction port of the cylinder chamber  40   b  of the second compression mechanism  38 , as a connecting destination of the outflow port  2  in the three-way solenoid valve V is not changed, the connecting destinations of the first inflow port  25  and second inflow port  26  may be reversed. 
       FIG. 5  is a schematic diagram explaining the configuration structure of the three-way solenoid valve V for the rotary compressor R and accumulator  34 . 
     Two refrigerant suction tubes  30 P and  25 Pa are extended from the accumulator  34 . One refrigerant suction tube  30 P is directly connected to the rotary compressor R. The other refrigerant suction tube  25 Pa is connected to the three-way solenoid valve V, and the suction tube  2 Pa connected to the three-way solenoid valve V is connected to the rotary compressor R. 
     The first inflow port  25  of the three-way solenoid valve V is connected to the refrigerant suction tube  25 Pa that is communicating with the accumulator  34 , and the second inflow port  26  is connected to the branch refrigerant discharge tube  26 Pa that is branched from the refrigerant discharge tube  30  of the rotary compressor R. The outflow port  2  is connected to the suction tube  2 Pa. 
     The most necessary thing is to locate the three-way solenoid valve V below the accumulator  34 , so that at least a part of it is positioned within a projection area of the accumulator  34 . In other words, the three-way solenoid valve V is located, so that at least a part of it is overlapped with the position of the accumulator  34  in its axial direction. Therefore, the installation space of the three-way solenoid valve V can be reduced. 
     Further, as the second inflow port  26  is connected to the branch refrigerant discharge tube  26 Pa, a switching mechanism can be incorporated in the compressor R as a single unit, piping and connecting work is unnecessary in manufacturing the refrigeration cycle equipment, and the manufacturability of the refrigeration cycle equipment can be improved. 
     As the three-way solenoid valve V is located immediately under the accumulator  34 , refrigerant piping of refrigeration cycle equipment having no switching means can be used without modification, and productivity is improved. 
     The invention is not limited to the embodiments described hereinbefore. The invention may be embodied by modifying the constituent elements in practical phases without departing from it spirit and characteristics. The invention may be embodied in various forms by appropriately combining the constituent elements disclosed in the embodiments described hereinbefore. 
     According to the invention, there is provided a three-way solenoid valve which is simplified in structure and improved in reliability, a rotary compressor which is provided with the three-way solenoid valve in the inflow side of a two-cylinder compression mechanism, and refrigeration cycle equipment which is provided with the rotary compressor for constituting a refrigeration cycle.