JP2017172504A - Scroll compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scroll compressor capable of improving durability and performance by properly keeping a back pressure load against thrust load of a movable scroll, regardless of an operation range.SOLUTION: A back-pressure control mechanism 12 for controlling a back-pressure load F2 including a back-pressure against a thrust load F1 of a movable scroll 3 has: a high-pressure flow channel 7d connecting a discharge chamber 8a and a back-pressure chamber 10, and supplying a high-pressure fluid on which a discharge pressure of a working fluid acts, to the back-pressure chamber 10; an intermediate-pressure flow channel 7m connecting the discharge chamber 8a and the back-pressure chamber 10, and supplying an intermediate-pressure fluid obtained by decompressing the high-pressure fluid, to the back-pressure chamber 10; a high-pressure chamber Pd in which the high-pressure flow channel 7d is opened; an intermediate-pressure chamber Pm in which the intermediate-pressure flow channel 7m is opened; a connection flow channel 16 connecting the high-pressure flow channel 7d and the intermediate-pressure flow channel 7m, and supplying the high-pressure fluid of the high-pressure flow channel 7d to the intermediate-pressure flow channel 7m; and an adjustment valve 18 opening and closing the connection flow channel 16 to adjust a pressure of the high-pressure flow channel 7d.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a scroll compressor, for example, a scroll compressor suitable for use in a vehicle air conditioner.

  The scroll compressor is provided with a shaft that is rotationally driven, a suction chamber for a working fluid containing lubricating oil, and a discharge chamber in the casing. A series of processes of fluid suction, compression, and discharge is performed. Further, the scroll compressor includes a thrust plate that slides on the back surface of the end plate of the movable scroll, a thrust receiving portion that receives a thrust load of the movable scroll generated by the compression reaction force of the working fluid, a thrust plate, and a thrust receiver. What has the back pressure chamber formed between the parts is known.

The back pressure chamber generates a back pressure that presses and urges the thrust plate, that is, the back of the movable scroll against the fixed scroll against the thrust load, and generates a back pressure load including the back pressure against the thrust load. Control is generally performed.
Patent Document 1 discloses that a back pressure chamber of a turning scroll (movable scroll) is communicated with a drive chamber (suction chamber) by a first and second thrust ring, a first back pressure chamber, Discloses a scroll compressor that is divided into an independent second back pressure chamber and switches the pressure of the second back pressure chamber to the discharge pressure or suction pressure of the working fluid according to the operation mode (heating operation, cooling operation). Yes. Thereby, it is supposed that an appropriate back pressure can be applied to the movable scroll in any operation.

JP 2002-21753 A

  In Patent Document 1, switching of the pressure in the second back pressure chamber according to the operation mode is performed by a four-way valve provided in a refrigeration cycle (refrigerant circuit) in which a scroll compressor is incorporated. This complicates the circuit configuration of the refrigerant circuit. In addition, the pressure in the back pressure chamber is switched by the refrigerant after flowing through the outdoor heat exchanger, the expansion valve, the indoor heat exchanger, etc. that constitute the refrigerant circuit, and the scroll compressor alone controls the back pressure chamber. Cannot be completed. Therefore, when the operating range of the scroll compressor becomes wide, the responsiveness of the back pressure control of the back pressure chamber deteriorates, and there is a possibility that an appropriate back pressure load against the thrust load of the movable scroll cannot be maintained.

  Specifically, when the back pressure load becomes excessive, the mechanical loss of the scroll compressor increases, and as a result, the durability of the scroll compressor deteriorates. On the other hand, if the back pressure load is insufficient, the compression chamber of the working fluid is not properly formed in the scroll compressor, which may cause performance deterioration due to a decrease in the compression efficiency of the scroll compressor.

  The present invention has been made in view of such problems, and the object of the present invention is to appropriately maintain a back pressure load against the thrust load of the movable scroll regardless of the operating range, and to improve durability and An object of the present invention is to provide a scroll compressor capable of realizing an improvement in performance.

  In order to achieve the above object, a scroll compressor according to the present invention includes a shaft that is rotationally driven, a suction chamber for a working fluid containing lubricating oil, and a discharge chamber in a casing, and a movable scroll coupled to the shaft is fixed. A scroll compressor that performs a series of processes of suction, compression, and discharge of working fluid by revolving orbiting with respect to a scroll, the thrust plate being slid on the back surface of the end plate of the movable scroll, and the working fluid Formed between the thrust plate and the thrust receiving portion for receiving the thrust load of the movable scroll generated by the compression reaction force, and presses the thrust plate against the fixed scroll against the thrust load. A back pressure chamber that generates a back pressure and a back pressure control mechanism that controls the back pressure load including the back pressure against the thrust load is provided. The mechanism communicates the discharge chamber and the back pressure chamber, connects the discharge chamber and the back pressure chamber with the high pressure flow path through which the high pressure fluid on which the discharge pressure of the working fluid acts, and the medium pressure reduced from the high pressure fluid. An intermediate pressure channel for supplying fluid to the back pressure chamber, a high pressure chamber partitioned into the back pressure chamber, the high pressure channel being opened, and a shaft side partitioned from the high pressure chamber of the back pressure chamber, and the intermediate pressure channel being opened The intermediate pressure chamber, the high pressure flow path and the intermediate pressure flow path are connected to each other, the high pressure fluid in the high pressure flow path is supplied to the intermediate pressure flow path, the communication flow path is opened and closed, and the pressure of the high pressure flow path is adjusted. And an adjusting valve for adjusting.

Preferably, the regulating valve opens and closes the communication channel according to the differential pressure between the high pressure channel and the intermediate pressure channel.
Preferably, the regulating valve is closed when the differential pressure is equal to or lower than a predetermined set upper limit pressure, and is opened when the differential pressure is greater than the set upper limit pressure, and the high-pressure flow path is at least higher than the pressure of the intermediate pressure flow path. And the open state is maintained until the pressure is equal to or lower than the set upper limit pressure.

  Preferably, the back pressure control mechanism is formed in the thrust receiving portion, and is inserted into the annular high pressure fluid supply groove to which the high pressure flow path is opened and the high pressure fluid is supplied, and in the back pressure chamber. A high pressure chamber to which the high pressure fluid is supplied is defined, and an annular pressing seal member that receives the pressure of the high pressure fluid and presses the thrust plate with a pressing force in a direction against the thrust load is further provided.

  According to the scroll compressor of the present invention, it is possible to provide a scroll compressor capable of appropriately maintaining the back pressure load against the thrust load of the movable scroll and realizing the durability improvement and the performance improvement regardless of the operation range. can do.

It is sectional drawing which shows the whole structure of the scroll compressor which concerns on one Embodiment of this invention. It is the figure which showed typically the back pressure control mechanism in the state in which the back pressure of the back pressure chamber of FIG. 1 is appropriate. It is the figure which showed typically the back pressure control mechanism in which the back pressure of the back pressure chamber of FIG. 2 is an excessive state.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a cross-sectional view of the overall structure of a scroll compressor 1 of the present invention. In the following description, the working fluid suction side and the discharge side (left side and right side in FIG. 1 respectively) of the scroll compressor 1 are defined as the front side and the rear side of the scroll compressor 1, respectively.
The scroll compressor 1 has a structure in which a fixed scroll 2, a movable scroll 3, a shaft 4, and an electric motor 5 as main components are housed in a cylindrical casing.

The fixed scroll 2 and the movable scroll 3 constituting the compression mechanism of the scroll compressor 1 are arranged to face each other in the axial direction of the scroll compressor 1 (the direction of the central axis CL).
The fixed scroll 2 includes a disc-shaped end plate 2a and a spiral wrap 2b integrally formed with the end plate 2a. Similarly, the movable scroll 3 includes a disc-shaped end plate 3a and an end plate 2a. It is comprised from the spiral wrap 3b integrally formed in the board 3a.

  The two scrolls 2 and 3 are engaged with the spiral wraps 2b and 3b, the tip end in the axial direction of the spiral wrap 2b of the fixed scroll 2 contacts the end plate 3a of the movable scroll 3, and the spiral wrap of the movable scroll 3 The tip end portions in the axial direction of 3b are arranged so as to contact the end plate 2a of the fixed scroll 2, respectively. Note that a tip seal is embedded at the axial tip portions of the spiral wraps 2b and 3b (in FIG. 1, only the tip seal 2c embedded at the axial tip portion of the spiral wrap 2b is shown). .

The scrolls 2 and 3 are arranged such that the side surfaces of the spiral wraps 2b and 3b are partially in contact with each other in a state where the phases of the spiral wraps 2b and 3b are shifted from each other by 180 degrees. Thereby, the compression chamber C which is sealed space is formed between both the spiral wraps 2b and 3b.
The movable scroll 3 is connected to the shaft 4 at a cylindrical boss 3c provided on the back surface 3a1 of the end plate 3a (the surface opposite to the surface on which the spiral wrap 3b is formed).

  The movable scroll 3 revolves around the central axis CL in a state where rotation is prevented by the action of the shaft 4 and a rotation prevention mechanism (not shown). As a result, the compression chamber C formed between the spiral wraps 2b and 3b moves from the outer end of the spiral wraps 2b and 3b toward the center, and the volume gradually decreases. As a result, the working fluid (for example, refrigerant gas) taken into the compression chamber C from the outer ends of the spiral wraps 2b and 3b is compressed.

  A discharge hole 2d penetrating through the end plate 2a is provided at a central portion in the radial direction of the end plate 2a of the fixed scroll 2. The working fluid compressed in the compression chamber C is discharged to the back surface 2a1 (surface opposite to the surface on which the spiral wrap 2b is formed) of the end plate 2a of the fixed scroll 2 through the discharge hole 2d. A one-way valve 2e such as a reed valve is provided at the outlet of the discharge hole 2d to prevent the working fluid from flowing back into the compression chamber C.

  The casing of the scroll compressor 1 includes a front casing 6, a center casing 7, and a rear casing 8. The front casing 6 and the center casing 7, and the center casing 7 and the rear casing 8 are fastened by fasteners (bolts, nuts, etc.) not shown on the axial end surfaces of the respective casings.

  The front casing 6 includes an end wall portion 6a formed in a substantially disc shape, a substantially cylindrical outer shell portion 6b extending rearward in the axial direction from an outer peripheral edge portion of the end wall portion 6a, and a radial direction of the end wall portion 6a. It is comprised from the cylindrical bearing support part 6c provided in the center part vicinity. Thus, a suction chamber S having a front end closed by the end wall portion 6a and a rear end opened is formed inside the front casing 6.

  The center casing 7 includes an outer shell portion 7a formed in a substantially cylindrical shape, and a substantially frustoconical bearing support portion 7b extending radially inward and axially forward from the outer shell portion 7a. . A fixed scroll 2 and a movable scroll 3 are accommodated inside the outer shell portion 7a of the center casing 7 and behind the bearing support portion 7b. A rolling bearing 7c that rotatably supports the shaft 4 is fitted in the vicinity of the front end portion of the bearing support portion 7b.

  The rear casing 8 is fastened to the center casing 7 with the outer peripheral edge of the end plate 2 a of the fixed scroll 2 sandwiched between the rear casing 8 and the center casing 7. A concave portion is formed in the central portion of the rear casing 8 in the radial direction, and a discharge chamber 8a defined by the end plate 2a of the fixed scroll 2 is formed in the concave portion.

  The shaft 4 is rotationally driven by the electric motor 5 and thereby has a function of causing the orbiting scroll 3 to revolve around the central axis CL. The shaft 4 includes a shaft body 4a and an eccentric pin portion 4c that protrudes from the rear end surface 4b of the shaft body 4a to the movable scroll 3 side. The shaft main body 4a is rotatably supported at its front end portion by a slide bearing 6d fitted to the inner periphery of the bearing support portion 6c of the front casing 6, and in the vicinity of the rear end surface 4b, the bearing of the center casing 7 is supported. It is rotatably supported by a rolling bearing 7c fitted to the inner periphery of the support portion 7b.

  An eccentric bush 4d is fitted and fixed to the outer periphery of the eccentric pin portion 4c. On the other hand, a sliding bearing 3e is fitted and fixed to the inner periphery of a cylindrical boss 3c provided on the back surface 3a1 of the movable scroll 3. The shaft 4 and the movable scroll 3 are slidably connected to each other by fitting the eccentric bush 4d to the inner periphery of the slide bearing 3e.

  A counterweight 4e is fitted and fixed at a portion between the rear end surface 4b of the shaft body 4a and the rolling bearing 7c. The center of gravity of the counterweight 4e is at a position that is 180 degrees out of phase with the eccentric pin portion 4c. For this reason, when the movable scroll 3 revolves with the rotation of the shaft 4, the counterweight 4 e cancels the unbalanced load generated around the central axis CL, and excessive vibration is generated in the shaft 4. Is preventing.

  The suction chamber S formed inside the front casing 6 accommodates an electric motor 5 for driving the shaft 4 to rotate. The electric motor 5 includes a stator 5a and a rotor 5b. The stator 5 a is formed in a cylindrical shape, and is fitted into the inner periphery of the outer shell portion 6 b of the front casing 6. The rotor 5 b is also formed in a cylindrical shape, and is fitted on the outer periphery of the shaft 4. The stator 5a and the rotor 5b are coaxially arranged with a minute radial gap between them, and by supplying current from the outside to a coil (not shown) provided in the stator 5a, the rotor 5b Rotate.

  A suction hole (not shown) is provided in the vicinity of the opened rear end portion of the outer shell portion 6b of the front casing 6, and the working fluid supplied through the suction port 6s passes through the suction hole to the inside of the front casing 6. Is sucked into the suction chamber S. The sucked working fluid flows into the center casing 7 through the open rear end portion of the outer shell portion 6b, passes through the fluid circulation holes (not shown) provided in the bearing support portion 7b, and the two spiral wraps 2b, It is introduced into the suction chamber 7s at the outer end of 3b, taken into the compression chamber C from the outer end side of the spiral wraps 2b and 3b, and compressed. The compressed working fluid is discharged to the discharge chamber 8a through the discharge hole 2d provided in the center portion in the radial direction of the end plate 2a of the fixed scroll 2, and is led out to the outside through a discharge port (not shown). .

  A flat thrust receiving portion 7e extending in the radial direction is formed on the movable scroll 3 side of the bearing support portion 7b of the center casing 7. An annular thrust plate 9 is disposed between the thrust receiving portion 7 e and the end plate 3 a of the movable scroll 3. The thrust plate 9 is slid on the back surface 3 a 1 of the end plate 3 a of the movable scroll 3, and forms a back pressure chamber 10 described later between the thrust plate 9 and the back surface 3 a 1 of the end plate 3 a of the movable scroll 3.

Between the outer peripheral part of the thrust plate 9, the outer peripheral part of the bearing support part 7b, and the outer peripheral part of the end plate 3a of the movable scroll 3, annular seal members 7f and 3d are interposed, respectively.
An oil separation wall 8 b is provided at the lower portion of the rear casing 8 in the vertical direction. On the other hand, an oil separation wall 2f is also provided on the back side of the end plate 2a of the fixed scroll 2 at a portion substantially facing the oil separation wall 8b in the axial direction. An oil storage chamber 8c is formed in the lower part of the rear casing 8 in the vertical direction of the oil separation walls 8b and 2f.

  The working fluid discharged from the discharge hole 2d provided in the end plate 2a of the fixed scroll 2 to the discharge chamber 8a contains lubricating oil for lubricating the bearings and sliding surfaces of the scroll compressor 1. This lubricating oil collides with the inner wall of the discharge chamber 8a and the oil separation walls 8b and 2f, and is separated from the working fluid by adhering to these walls. The separated lubricating oil flows down to the oil storage chamber 8c by the action of gravity and is stored in the oil storage chamber 8c.

  A high-pressure oil supply passage 8d is formed in the lower part of the rear casing 8 in the vertical direction. One end of the high-pressure oil supply flow path 8d is open at the lowest part in the vertical direction of the oil storage chamber 8c. The other end of the high-pressure oil supply flow path 8d extends to an oil manifold 8e provided at the lower part in the vertical direction on the joint end surface of the rear casing 8 with the center casing 7.

  The lubricating oil separated from the working fluid in the discharge chamber 8a in the rear casing 8 and stored in the oil storage chamber 8c is a high-pressure oil having a high pressure at which the discharge pressure of the scroll compressor 1 acts. This high-pressure oil is introduced into a high-pressure oil supply flow path 8 d formed in the rear casing 8, and reaches an oil manifold 8 e provided on a joint end surface between the rear casing 8 and the center casing 7.

  A high-pressure oil supply flow path (high-pressure flow path) 7d and an intermediate-pressure oil supply flow communicating the oil manifold 8e and the back pressure chamber 10 from the lower part in the vertical direction of the outer shell part 7a of the center casing 7 toward the bearing support part 7b. A passage (intermediate pressure passage) 7m is formed. In FIG. 1, the high-pressure oil supply channel 7d and the intermediate-pressure oil supply channel 7m are illustrated as being drilled at the same position in the circumferential direction, but these are different positions in the circumferential direction. It may be drilled in.

  One end of each of the high-pressure oil supply flow path 7d and the intermediate-pressure oil supply flow path 7m opens to the joint end surface of the center casing 7 with the rear casing 8, and extends axially forward in the outer shell portion 7a. It has a flow path portion and a radial flow path portion extending radially inward from the front end of the axial flow path portion inside the bearing support portion 7b.

  The other end of the high-pressure oil supply flow path 7d opens into the back pressure chamber 10 via another axial flow path portion extending axially rearward from the front end of the radial flow path portion. On the other hand, the other end of the intermediate pressure oil supply flow path 7m opens into the back pressure chamber 10 at the end of the radial flow path portion. Further, in the axial flow path portion of the intermediate pressure oil supply flow path 7m, the pressure of the high pressure oil supplied to the inlet opening is reduced to at least an intermediate pressure oil that is higher than the low pressure at which the suction chamber S acts. An orifice (medium pressure oil pressure reducing mechanism) 7n is embedded.

The high pressure oil supplied to the oil manifold 8e flows into the high pressure oil supply channel 7d and the intermediate pressure oil supply channel 7m. The high-pressure oil supply flow path 8d may be provided in two, one in communication with the high-pressure oil supply flow path 7d and one in communication with the medium-pressure oil supply flow path 7m. There is no need to provide the manifold 8e.
The shaft body 4a has a first oil passage 4h drilled from the rear end face 4b in the axial direction forward and a second oil passage 4j drilled from the front end face in the axial rearward direction. Is provided.

  Since the eccentric pin portion 4c protrudes from the rear end surface 4b of the shaft body 4a, the first oil passage 4h extends not on the central axis CL but at a position eccentric from the central axis CL. On the other hand, the second oil flow path 4j extends on the central axis CL. The first and second oil passages 4h and 4j communicate with each other, and as a whole, an oil passage that communicates with the back pressure chamber 10 at the rear end surface 4b of the shaft body 4a is formed. An orifice 4k is embedded at the front end of the second oil flow path 4j. The orifice 4k maintains the pressure of the oil passage so as to be the same as that of the back pressure chamber 10.

  A seal ring 4f is fitted at a position in front of the rolling bearing 7c in the shaft body 4a. An annular seal member 4g is fitted in a groove provided on the outer peripheral surface of the seal ring 4f. The seal member 4g slides on the inner peripheral surface of the bearing support portion 7b of the center casing 7, whereby the space between the back pressure chamber 10 and the suction chamber S is sealed.

  In the scroll compressor 1 configured as described above, the direction in which the movable scroll 3 is pulled away from the fixed scroll 2 due to the differential pressure between the pressure in the compression chamber C and the back pressure in the back pressure chamber 10 (see FIG. A thrust load of 1) is applied to the left. This thrust load acts from the thrust plate 9 toward the thrust receiving portion 7e. For this reason, in the scroll compressor 1 of the present embodiment, a back pressure load that presses and urges the movable scroll 3 against the fixed scroll 2 against the thrust load in order to guarantee its high-efficiency operation in a wide operating range. A back pressure control mechanism 12 is provided for generating and maintaining this back pressure load appropriately.

Hereinafter, the back pressure control mechanism 12 will be described in detail with reference to FIGS. 2 and 3.
FIG. 2 is a diagram schematically showing the back pressure control mechanism 12 in a state where the back pressure in the back pressure chamber 10 is appropriate.
The thrust receiving portion 7e is provided with a high-pressure oil supply groove (high-pressure fluid supply groove) 7g over the entire circumference in the radial direction. The sealing member 7f described above is fitted into the outer annular groove 7h formed in the thrust receiving portion 7e. The high pressure oil supply groove 7g is formed radially inward from the outer annular groove 7h of the thrust receiving portion 7e.

  An annular pressure seal member 14 made of an elastic material is fitted in the high pressure oil supply groove 7g. The pressing seal member 14 includes a pressing portion 14a formed in a planar shape, and a side wall portion 14b extending in a taper shape from the inner and outer peripheral edges of the pressing portion 14a in the axial direction. The pressure seal member 14 is fitted in the high-pressure oil supply groove 7g in a state where the side wall portions 14b are elastically deformed in a direction in which the both side wall portions 14b approach each other. As a result, the pressure seal member 14 is axially moved in the high pressure oil supply groove 7g while maintaining the state in which both side walls 14b are in fluid-tight contact with the inner and outer groove walls of the high pressure oil supply groove 7g. It is configured to be movable.

  The high-pressure oil supply groove 7g has a high-pressure oil supply flow path 7d opened at one place in the lower part in the vertical direction. The high-pressure oil supplied to the high-pressure oil supply flow path 7d is supplied to the high-pressure oil supply groove 7g, and is introduced into a space surrounded by the pressing portion 14a and the side wall portions 14b formed inside the pressing seal member 14. The This space is defined as a high pressure chamber Pd to which high pressure oil is supplied in the back pressure chamber 10. Further, the back pressure chamber 10 is partitioned with a medium pressure chamber Pm in which a medium pressure oil supply channel 7m is opened on the shaft 4 side of the high pressure chamber Pd of the back pressure chamber 10.

The high-pressure chamber Pd is supplied with high-pressure oil (high-pressure fluid) indicated by a solid line from the high-pressure oil supply flow path 7d, and the medium-pressure chamber Pm is a one-dot chain line reduced in pressure from the medium-pressure oil supply flow path 7m through the orifice 7n. The medium pressure oil (medium pressure fluid) shown by is supplied.
If it demonstrates using FIG. 1, the lubricating oil which flowed into the intermediate pressure chamber Pm will be used for lubrication of the rolling bearing 7c and the sliding bearing 3e.

  The lubricating oil in the intermediate pressure chamber Pm then flows into the first oil passage 4h provided in the shaft body 4a of the shaft 4, and further passes through the second oil passage 4j and the orifice 4k embedded in the downstream end thereof. Then, it flows into the oil discharge chamber 6e. Lubricating oil flows from the oil discharge chamber 6e into the suction chamber S while lubricating the sliding bearing 6d, passes through the space around the stator 5a and the rotor 5b of the electric motor 5, and reaches the rear of the suction chamber S.

  The lubricating oil that has reached the rear of the suction chamber S merges with the working fluid supplied into the suction chamber S through the suction port 6s, and is again introduced into the suction chamber 7s at the outer ends of the spiral wraps 2b and 3b. . Note that the lubricating oil path from the intermediate pressure chamber Pm to the suction chamber S does not pass through the shaft 4 by using, for example, a through hole provided in the bearing support portion 7b of the center casing 7. It may be configured.

In this way, the lubricating oil circulates inside the scroll compressor 1.
Here, the seal member 7f is pressed by the thrust load F1 generated by the compression reaction force of the working fluid accompanying the formation of the compression chamber C. On the other hand, the intermediate pressure chamber Pm presses the movable scroll 3 with the pressing force F2a based on the back pressure, and the high pressure chamber Pd presses the thrust plate 9 with the pressing force F2b based on the back pressure.

  That is, the back pressure load that opposes the thrust load F1 is roughly configured by a resultant force with the pressing forces F2a and F2b (hereinafter collectively referred to as the back pressure load F2). In the above description, it has been described that the lubricating oil separated from the working fluid in the discharge chamber 8a in the rear casing 8 is supplied to the high pressure chamber Pd and the intermediate pressure chamber Pm. Even when the working fluid is supplied from the chamber 8a to the high pressure chamber Pd and the intermediate pressure chamber Pm, the back pressure control can be performed in the same manner.

  In this embodiment, the outer shell portion 7a of the center casing 7 communicates with the high-pressure oil supply channel 7d and the intermediate-pressure oil supply channel 7m, and the high-pressure oil in the high-pressure oil supply channel 7d is used as the intermediate-pressure oil. A communication channel 16 for supplying the supply channel 7m is formed. In addition, an orifice (high pressure oil pressure reducing mechanism) 7i is provided on the upstream side of the communication channel 16 of the high pressure oil supply channel 7d. The communication flow path 16 is provided with a differential pressure valve (regulation valve) 18. The differential pressure valve 18 is built in the outer shell portion 7a of the center casing 7, and has a mechanism for detecting the differential pressure between the high pressure oil supply channel 7d and the intermediate pressure oil supply channel 7m, and according to the detected differential pressure. It is a mechanical automatic valve that automatically opens and closes the communication channel 16.

  The differential pressure valve 18 is closed when a predetermined set upper limit pressure for starting the operation is defined in advance and the detected differential pressure is equal to or lower than the set upper limit pressure. On the other hand, the differential pressure valve 18 opens when the detected differential pressure becomes greater than the set upper limit pressure, and the high pressure oil supply passage 7d is at least larger than the pressure Pm1 of the medium pressure oil at the intermediate pressure oil supply passage 7m. Further, the open state is maintained until the pressure becomes Pm2 (pressure reduced from the high pressure oil Pd) equal to or lower than the set upper limit pressure. The set upper limit pressure of the differential pressure is set within a range in which an appropriate pressure in the high pressure chamber Pd can be secured. Further, the relational expression of at least Ps <Pm1 <Pm2 <Pd is established for the high pressure oil Pd, the medium pressure oil Pm1, the Pm2 decompressed from the high pressure oil Pd, and the suction pressure Ps.

Hereinafter, the operation of the differential pressure valve 18 when the back pressure chamber 10 is in proper back pressure will be described.
As shown in FIG. 2, when the back pressure of the back pressure chamber 10 is appropriate, the differential pressure between the high pressure oil supply passage 7d and the intermediate pressure oil supply passage 7m is equal to or lower than the set upper limit pressure, and the differential pressure valve 18 is closed. It is operating. As a result, the high-pressure oil that has flowed into the high-pressure oil supply flow path 7d flows into the high-pressure chamber Pd at a pressure Pd substantially without a pressure drop at the orifice 7i, as shown by the solid line. On the other hand, the high-pressure oil that has flowed into the medium-pressure oil supply flow path 7m is depressurized by the orifice 7n as indicated by the alternate long and short dash line, and becomes medium-pressure oil at the pressure Pm1 and flows into the medium-pressure chamber Pm. In this state, the pressure in the high pressure chamber Pd is properly maintained, and the back pressure load F2 against the thrust load F1 is properly generated.

FIG. 3 is a diagram schematically showing the back pressure control mechanism 12 in which the back pressure in the back pressure chamber 10 is excessive.
In this case, the operating range used in the scroll compressor 1 is changed from the state shown in FIG. 2, and the pressure in the high-pressure chamber Pd, and hence the pressing force F2b in the high-pressure chamber Pd, is excessive compared to when the back pressure is appropriate. ing. For this reason, the differential pressure between the high pressure oil supply channel 7d and the intermediate pressure oil supply channel 7m is larger than the set upper limit pressure, and the differential pressure valve 18 has at least the pressure Pm1 of the medium pressure oil in the high pressure oil supply channel 7d. And the open state is maintained until a pressure of Pm2 equal to or lower than the set upper limit pressure is reached.

As the differential pressure valve 18 is opened, a part of the high-pressure oil that has flowed into the high-pressure oil supply flow path 7d flows into the intermediate-pressure oil supply flow path 7m via the communication flow path 16, as shown by the solid line. Accordingly, it flows into the high pressure chamber Pd at a pressure Pm2 that is reduced from the pressure Pd of the high pressure oil.
On the other hand, the high pressure oil that has flowed into the intermediate pressure oil supply flow path 7m is depressurized by the orifice 7n, the pressure rises due to the high pressure oil flowing into the intermediate pressure oil supply flow path 7m via the communication flow path 16, The pressure in the intermediate pressure chamber Pm temporarily increases.

  However, when the orifice 4k of the second oil flow path 4j built in the shaft 4 detects an increase in the pressure of the intermediate pressure chamber Pm and is opened, the intermediate pressure chamber Pm communicates with the suction chamber S side. The pressure in the pressure chamber Pm is released. Therefore, the high-pressure oil that has flowed into the medium-pressure oil supply flow path 7m finally becomes the medium-pressure oil at the pressure Pm1 as shown by the one-dot chain line in FIG. Flows into the chamber Pm. In this state, the excessive back pressure in the high pressure chamber Pd is eliminated, and the back pressure load F2 against the thrust load F1 is appropriately generated.

  As described above, in the present embodiment, the communication channel 16 that connects the high-pressure oil supply channel 7d and the intermediate-pressure oil supply channel 7m, the high-pressure oil supply channel 7d, and the intermediate-pressure oil supply channel 7m A differential pressure valve 18 that opens and closes the communication channel 16 according to the differential pressure is provided. As a result, even if the pressure Pd of the high-pressure oil in the high-pressure oil supply channel 7d and thus the back pressure in the high-pressure chamber Pd becomes excessive, the differential pressure between the high-pressure oil supply channel 7d and the intermediate-pressure oil supply channel 7m is reduced. Upon detection, the differential pressure valve 18 is opened, and a part of the high-pressure oil in the high-pressure oil supply channel 7d is supplied to the intermediate-pressure oil supply channel 7m. Accordingly, the excessive back pressure in the high pressure chamber Pd and hence the back pressure chamber 10 is quickly eliminated, and the pressure Pd in the high pressure chamber Pd and thus the back pressure load F2 is quickly optimized.

  Here, when the scroll compressor 1 is incorporated into a refrigeration cycle of a vehicle air conditioner, for example, during the cooling operation of the vehicle air conditioner, the suction pressure of the working fluid in the scroll compressor 1 is large and the discharge pressure tends to be small. is there. For this reason, since the compression reaction force of the working fluid, and hence the thrust load F1, increases, it is necessary to increase the back pressure load F2 against the thrust load F1.

  On the other hand, during heating operation, the suction pressure of the working fluid in the scroll compressor 1 tends to be small and the discharge pressure tends to be large. In this case, since the compression reaction force of the working fluid and the thrust load F1 are reduced, if the same back pressure load F2 as that during the cooling operation is generated, the back pressure load F2 becomes excessive and the mechanical loss of the scroll compressor 1 increases. However, there is a problem that the durability deteriorates.

  However, even when the operation range of the scroll compressor 1 becomes wide due to the application of the present invention, the operation range used in the scroll compressor 1 is expanded during heating operation in the vehicle air conditioner, With a simple configuration in which the communication flow path 16 and the differential pressure valve 18 are provided in the center casing 7 of the scroll compressor 1, the responsiveness of the back pressure control of the back pressure chamber 10 is greatly improved and mechanical loss is reduced. The scroll compressor 1 with improved compression efficiency can be provided.

The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the communication flow channel 16 is provided with the differential pressure valve 18 that opens and closes the communication flow channel 16 according to the differential pressure between the high pressure oil supply flow channel 7d and the intermediate pressure oil supply flow channel 7m. However, the valve provided in the communication flow path 16 is not limited to the differential pressure valve 18 as long as it is an adjustment valve that can be opened and closed to adjust the pressure of the high-pressure oil supply flow path 7d.

  In the above embodiment, the high pressure chamber Pd is formed inside the pressure seal member 14 fitted in the high pressure oil supply groove 7g, and the pressure seal member 14 presses the thrust plate 9 to generate the back pressure load F2. ing. However, the present invention is not limited to this, and the high-pressure chamber Pd in which the high-pressure oil supply channel 7d is opened may be partitioned into the back pressure chamber 10 by a seal member (not shown). Even in this case, by providing the communication flow path 16 and the differential pressure valve 18, it is possible to quickly eliminate the excessive back pressure of the high pressure chamber Pd and thus the back pressure chamber 10.

DESCRIPTION OF SYMBOLS 1 Scroll compressor 2 Fixed scroll 3 Movable scroll 3a End plate 3a1 Back surface 4 Shaft 6, 7, 8 Casing 7d High pressure oil supply flow path (high pressure flow path)
7e Thrust receiving portion 7f Seal member 7g High pressure oil supply groove (high pressure fluid supply groove)
7m Medium pressure oil supply channel (Medium pressure channel)
7n orifice (medium pressure oil pressure reducing mechanism)
7i orifice (high pressure oil pressure reducing mechanism)
8a Discharge chamber 9 Thrust plate 10 Back pressure chamber 12 Back pressure control mechanism 14 Press seal member 16 Communication channel 18 Adjustment valve (differential pressure valve)
F1 Thrust load F2 Back pressure load Pd High pressure chamber Pm Medium pressure chamber S Suction chamber

Claims (4)

The casing is provided with a shaft that is driven to rotate, a suction chamber for a working fluid containing lubricating oil, and a discharge chamber. The movable scroll connected to the shaft revolves with respect to the fixed scroll to suck the working fluid. A scroll compressor that performs a series of processes of compression and discharge,
A thrust plate slid on the back surface of the end plate of the movable scroll;
A thrust receiving portion for receiving a thrust load of the movable scroll generated by a compression reaction force of the working fluid;
A back pressure chamber that is formed between the thrust plate and the thrust receiving portion and generates a back pressure that presses and thrusts the thrust plate against the fixed scroll against the thrust load;
A back pressure control mechanism for controlling a back pressure load including the back pressure against the thrust load,
The back pressure control mechanism is
A high-pressure channel that communicates the discharge chamber and the back pressure chamber, and through which a high-pressure fluid on which the discharge pressure of the working fluid acts;
An intermediate pressure flow path that communicates the discharge chamber and the back pressure chamber, and supplies the back pressure chamber with an intermediate pressure fluid decompressed from the high pressure fluid;
A high-pressure chamber partitioned into the back-pressure chamber and having the high-pressure channel opened;
An intermediate pressure chamber partitioned from the high pressure chamber of the back pressure chamber on the shaft side and having the intermediate pressure flow path opened;
A communication channel that connects the high-pressure channel and the intermediate-pressure channel, and supplies the high-pressure fluid of the high-pressure channel to the intermediate-pressure channel;
A scroll compressor having an adjustment valve that opens and closes the communication channel and adjusts the pressure of the high-pressure channel.   2. The scroll compressor according to claim 1, wherein the adjustment valve opens and closes the communication channel according to a differential pressure between the high pressure channel and the intermediate pressure channel.   The adjusting valve is closed when the differential pressure is equal to or lower than a predetermined set upper limit pressure, and is opened when the differential pressure is greater than the set upper limit pressure, and the high pressure channel is at least the intermediate pressure channel. The scroll compressor according to claim 2, wherein the scroll compressor is maintained in an open state until a pressure that is greater than a predetermined pressure and equal to or less than the set upper limit pressure. The back pressure control mechanism is
An annular high-pressure fluid supply groove that is formed in the thrust receiving portion and in which the high-pressure channel is opened and the high-pressure fluid is supplied;
The high-pressure fluid is inserted into the high-pressure fluid supply groove, defines the high-pressure chamber to which the high-pressure fluid is supplied in the back pressure chamber, and receives a pressure of the high-pressure fluid to exert a pressing force in a direction against the thrust load. The scroll compressor according to any one of claims 1 to 3, further comprising an annular pressure seal member that presses the thrust plate.

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