JP2020007928A - Scroll compressor - Google Patents

Abstract

To suppress the generation of excessive pressing force of a movable scroll on a fixed scroll.SOLUTION: The scroll compressor includes the fixed scroll fixed into a casing, the movable scroll to be turned in engagement with the fixed scroll, a rotary shaft for turning the movable scroll while supporting it at its eccentric shaft eccentric from a main shaft, and a slide bush mechanism provided between a bearing and the eccentric shaft of the movable scroll for changing its sliding direction at the time a gas load is applied thereto according to the rotation speed of the rotary shaft to change the pressing force of the movable scroll on the fixed scroll.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a scroll compressor.

  It has a fixed scroll and an orbiting scroll that orbits with respect to the fixed scroll. A plurality of spiral wraps are formed on mutually facing surfaces of the end plates of the fixed scroll and the orbiting scroll. The compression chamber is formed, and a slide bush having a slide surface that forms a predetermined angle with respect to the load direction of the gas in the compression chamber is interposed on the eccentric shaft of the rotating shaft that drives the orbiting scroll, and the gas in the compression chamber is A scroll compressor configured to increase the amount of eccentricity of an eccentric shaft when a load is applied is known (for example, see Patent Document 1).

Japanese Patent No. 5384017

  Here, if a configuration is adopted in which the amount of eccentricity of the movable scroll becomes large regardless of the rotational speed of the rotating shaft of the movable scroll when a load of gas in the compression chamber is applied, for example, the rotating shaft of the movable scroll When the rotation speed of the scroll becomes high, an excessive pressing force of the movable scroll against the fixed scroll is generated.

  An object of the present invention is to suppress the generation of an excessive pressing force of a movable scroll against a fixed scroll.

  With this object in mind, the present invention provides a fixed scroll fixed in a housing, a movable scroll that meshes with the fixed scroll and turns, and a rotary shaft that supports and turns the movable scroll with an eccentric shaft eccentric from the main shaft. Between the bearing of the movable scroll and the eccentric shaft, and by changing the sliding direction when a gas load is applied according to the rotation speed of the rotating shaft, the pressing force of the movable scroll against the fixed scroll is changed. The present invention provides a scroll compressor having a slide bush mechanism for causing a scroll.

  Here, the slide bush mechanism may suppress the pressing force of the movable scroll against the fixed scroll when the rotation speed of the rotation shaft increases.

  In that case, the slide bush mechanism may be configured to suppress the pressing force by suppressing the amount of eccentricity of the movable scroll from the main shaft.

  Further, the slide bush mechanism may be configured to suppress the amount of eccentricity by using the first bush fitted to the bearing of the movable scroll and the second bush fitted to the eccentric shaft.

  Further, the first bush is slidable along a slide surface between the first bush and the second bush, and the slide bush mechanism is configured to move the first bush so that the amount of eccentricity is reduced by a load on the movable scroll. The eccentricity may be suppressed by turning the bush in a predetermined slidable direction.

  In this case, the first bush rotates in accordance with the rotation of the second bush, and the second bush rotates in a predetermined state around the eccentric shaft to a predetermined angle, so that the slide surface is formed in a predetermined state. In the direction of.

  The predetermined state is at least two states of the second bush, and each state is one of at least two states rotated around the eccentric shaft to an angle corresponding to each state. Good.

  Further, the second bush may switch from a state other than the predetermined state of the at least two states to the predetermined state when the rotation speed of the rotating shaft exceeds the predetermined rotation speed.

  In addition, the predetermined rotation speed is the rotation when the magnitude relationship between the first torque generated by the rotation of the bearing of the orbiting scroll and the second torque generated by the centrifugal force on the first bush and the second bush is reversed. It may be speed.

  Further, the first torque may change as a linear function of the rotation speed of the rotation shaft, and the second torque may change as a quadratic function of the rotation speed of the rotation shaft.

  On the other hand, the center of gravity of the first bush and the second bush may be located at a position delayed in the rotation direction of the rotation shaft from a straight line connecting the center of the main shaft and the center of the eccentric shaft.

  In addition, the present invention may further include a protrusion connected to at least one of the first bush and the second bush for adjusting the center of gravity.

  Further, in the present invention, at least one of the first bush and the second bush may be provided with a concave portion for adjusting the center of gravity.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the excessive pressing force with respect to a fixed scroll of a movable scroll can be suppressed.

It is an axial sectional view of the scroll compressor concerning this embodiment. It is a top view of a slide bush mechanism. (A) is a diagram showing a state of the slide bush mechanism when the rotation speed of the rotating shaft is low, and (b) is a state of the slide bush mechanism when the rotation speed of the rotation shaft is high. FIG. 4 is a graph showing changes in the bearing torque _Tsh and the centrifugal force torque _Tc when the rotation speed of the rotating shaft changes. It is a top view of the 1st modification of a slide bush mechanism. It is a top view of the 2nd modification of a slide bush mechanism.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an axial sectional view of a scroll compressor 1 according to the present embodiment.
The scroll compressor 1 is a compressor widely used for an air conditioner, a refrigerator, and a heat pump. FIG. 1 is a longitudinal sectional view of a hermetic scroll compressor used in a refrigerant circuit of an air conditioner.

  The scroll compressor 1 includes a compression unit 10 that compresses a refrigerant, a drive motor 20 that drives the compression unit 10, and a casing 30 that is an example of a housing that houses the compression unit 10 and the drive motor 20. I have. The scroll compressor 1 according to the present embodiment is a vertical scroll compressor that is disposed such that an axial direction of a rotating shaft 23 of the drive motor 20 described later is the direction of gravity. Hereinafter, the axial direction of the rotating shaft 23 may be referred to as “up and down direction”, the upper side as viewed in FIG. 1 may be referred to as “upper side”, and the lower side may be referred to as “lower side”. Here, a vertical scroll compressor will be described as an example, but the present invention is also applicable to a horizontal scroll compressor.

First, the compression unit 10 will be described.
The compression unit 10 includes a fixed scroll 11 fixed in the casing 30, a movable scroll 12 that turns while being engaged with the fixed scroll 11, a frame 13 fixed to the casing 30 and holding the fixed scroll 11, And an Oldham key 14 for turning the movable scroll 12 without rotating.

  The fixed scroll 11 includes a cylindrical portion 111, an end plate 112 that covers an upper opening of the cylindrical portion 111, and a protruding portion that protrudes radially outward from a lower end of the cylindrical portion 111. 113. Further, the fixed scroll 11 has a fixed-side spiral body 114 projecting downward from a lower end portion of the end plate 112 and formed in a spiral shape when viewed from below. The material of the fixed scroll 11 can be exemplified to be a cast iron material, for example, gray cast iron of FC250.

The cylindrical portion 111 has a radial through-hole 111a formed therein. The through hole 111a functions as a suction port for sucking refrigerant into a space surrounded by the cylindrical portion 111, the end plate 112, and the movable scroll 12.
A vertical through-hole 112a is formed at the center of the end plate 112. The through hole 112a functions as a discharge port for discharging the refrigerant from a space surrounded by the end plate 112, the fixed scroll 114, and the movable scroll 12.
The fixed scroll 11 configured as described above is fixed to the frame 13 by a positioning means such as a bolt or a positioning pin which is passed through a vertical through hole formed in the protrusion 113.

  The orbiting scroll 12 includes a disk-shaped end plate 121, a movable-side scroll 122 projecting upward from an upper end of the end plate 121 and formed in a spiral shape when viewed from above, and an end plate. 121, a cylindrical portion 123 protruding downward from a lower end portion. The material of the movable scroll 12 can be exemplified by an FC material or an FCD material.

The movable scroll 122 is a spiral having a shape that meshes with the fixed scroll 114 of the fixed scroll 11. The movable scroll 122 and the fixed scroll 114 of the fixed scroll 11 are arranged in a space formed between the cylindrical portion 111 and the end plate 112 of the fixed scroll 11 and the end plate 121 and compressed. A chamber 15 is defined. Then, the volume of the compression chamber 15 is reduced by circularly moving the movable-side spiral 122 with respect to the fixed stationary-side spiral 114, thereby compressing the refrigerant. In other words, the internal space between the fixed-side spiral 114 and the movable-side spiral 122 contracts toward the center of rotation and compresses the refrigerant.
An eccentric shaft 232 of the rotary shaft 23 described below is fitted into the cylindrical portion 123 via a slide bearing. Thus, the cylindrical portion 123 functions as a bearing for the eccentric shaft 232.

  The frame 13 includes a first cylindrical portion 131 having a cylindrical shape, and a second cylindrical portion 132 having a cylindrical shape protruding downward from a lower end of the first cylindrical portion 131. The outer peripheral surface of the first cylindrical portion 131 of the frame 13 is fixed to a later-described central casing 31 of the casing 30. A rotating shaft 23 of the drive motor 20 described below is fitted inside the first cylindrical portion 131 and the second cylindrical portion 132 via a journal bearing. As described above, the frame 13 also functions as a bearing that rotatably supports the rotating shaft 23.

  The outer peripheral portion of the first cylindrical portion 131 is provided with a protruding portion 131a protruding upward from the upper end surface. A female screw is formed in the projecting portion 131a, and a bolt passed through a through hole formed in the projecting portion 113 of the fixed scroll 11 is fastened to the female screw, whereby the fixed scroll 11 is attached to the frame 13. Can be

The first cylindrical portion 131 has a first recess 131b and a second recess 131c that are recessed downward from the upper end surface. In the radial direction, the first concave portion 131b is formed at the center, and the second concave portion 131c is formed between the first concave portion 131b and the protruding portion 131a. Then, the cylindrical portion 123 of the movable scroll 12 is inserted into the first recess 131b. An Oldham key 14 that is disposed between the frame 13 and the movable scroll 12 and that prevents the movable scroll 12 from rotating is disposed in the second recess 131c.
Further, the first cylindrical portion 131 is formed with a groove 131d extending vertically from the center to the lower portion of the outer peripheral portion. The first cylindrical portion 131 has a radial communication hole 131e communicating the inside of the first recess 131b with the groove 131d.
The rotating shaft 23 is fitted on the inner periphery of the second cylindrical portion 132 via a journal bearing, and the second cylindrical portion 132 functions as a bearing that rotatably supports the rotating shaft 23.

  Note that a discharge passage (not shown) for discharging the refrigerant compressed by the fixed scroll 11 and the movable scroll 12 is formed in the above-described compression unit 10. One end of the discharge passage is connected to the through hole 112a of the end plate 112 that discharges the refrigerant from the space surrounded by the fixed scroll 11 and the movable scroll 12, and the other end is a space below the frame 13 in the casing 30. It is connected with.

Next, the drive motor 20 will be described.
The drive motor 20 is fixed to the casing 30 below the compression unit 10.
The drive motor 20 includes a stator 21 that forms a stator, a rotor 22 that forms a rotor, a rotation shaft 23 that supports the rotor 22 and rotates with respect to a casing 30, and rotatably supports the rotation shaft 23. And a support member 24.

The stator 21 has a stator main body 211 and a coil 212 wound around the stator main body 211.
The stator main body 211 is a laminated body in which many electromagnetic steel sheets are laminated, and has a substantially cylindrical shape. The diameter of the outer peripheral surface of the stator main body 211 is formed larger than the diameter of the inner peripheral surface of a later-described central casing 31 of the casing 30, and the stator main body 211 (stator 21) is fitted into the central casing 31 by fitting. It is fitted. Examples of a method of fitting the stator main body 211 to the center casing 31 include shrink fitting and press fitting.

  In addition, the stator body 211 has a plurality of teeth (not shown) in a circumferential direction at an inner portion facing the outer periphery of the rotor 22. The coil 212 is arranged in a notch (not shown) existing between adjacent teeth. In the stator 21 according to the present embodiment, it can be illustrated that the coil 212 is a concentrated winding inserted in a notch existing between a plurality of adjacent teeth.

The rotor 22 is a laminate in which a number of ring-shaped electromagnetic steel sheets are laminated, and has a cylindrical shape as a whole. The diameter of the inner peripheral surface of the rotor 22 is formed smaller than the diameter of the outer peripheral surface of the rotating shaft 23, and the rotor 22 is fitted into the rotating shaft 23 with an interference fit. The method of fitting the rotating shaft 23 into the rotor 22 can be exemplified by press fitting. Then, the rotor 22 is fixed to the rotating shaft 23 and rotates together with the rotating shaft 23. In addition, the rotor 22 can be exemplified as having a permanent magnet embedded therein.
The diameter of the outer peripheral surface of the rotor 22 is formed smaller than the diameter of the inner peripheral surface of the stator main body 211 of the stator 21, and there is a gap between the rotor 22 and the stator 21.

The rotation shaft 23 has a main shaft 231 to which the rotor 22 is fitted, and an eccentric shaft 232 provided on the main shaft 231 and having an axis eccentric from the axis of the main shaft 231.
The lower part of the main shaft 231 is rotatably supported by the support member 24, and the upper part is rotatably supported by the frame 13 of the compression unit 10. The eccentric shaft 232 is rotatably supported by the cylindrical portion 123 of the orbiting scroll 12.

  The rotary shaft 23 has a through hole 233 that passes through the rotary shaft 23 in the axial direction. The rotary shaft 23 has a first communication hole 234 that communicates the through hole 233 with the bearing of the support member 24, a second communication hole 235 that communicates the through hole 233 with the bearing of the frame 13, A third communication hole 236 that connects the hole 233 and the bearing of the cylindrical portion 123 is formed in the radial direction.

The support member 24 includes a first cylindrical portion 241 having a cylindrical shape, and a second cylindrical portion 242 having a cylindrical shape projecting downward from a lower end of the first cylindrical portion 241. The support member 24 is fixed to the central casing 31 such that an outer peripheral surface of the first cylindrical portion 241 faces an inner peripheral surface of a later-described central casing 31 of the casing 30. The rotating shaft 23 is fitted inside the first cylindrical portion 241 and the second cylindrical portion 242 via a journal bearing. As described above, the support member 24 functions as a bearing that rotatably supports the rotation shaft 23.
Further, the first cylindrical portion 241 is formed with a hole (not shown) or a groove (not shown) for communicating a space above and below the first cylindrical portion 241.
At the lower end of the second cylindrical portion 242 of the support member 24, a pump 243 for pumping lubricating oil is mounted.

Next, the casing 30 will be described.
The casing 30 includes a cylindrical central casing 31 arranged at the center in the vertical direction, an upper casing 32 covering an upper opening in the central casing 31, and a lower casing 33 covering a lower opening in the central casing 31. And The casing 30 includes a discharge unit 34 that discharges the high-pressure refrigerant compressed by the compression unit 10 to the outside of the casing 30 and a suction unit 35 that suctions the refrigerant from outside the casing 30.

As described above, the frame 13 of the compression unit 10, the stator 21 of the drive motor 20, and the support member 24 are fixed to the central casing 31. Further, the discharge part 34 and the suction part 35 are configured by inserting tubes into through holes formed in the central casing 31. The suction portion 35 is provided at a position corresponding to the through-hole 111 a formed in the cylindrical portion 111 of the fixed scroll 11, and is surrounded by the fixed scroll 11 and the movable scroll 12 from outside the casing 30. A refrigerant is sucked into the space.
The lower casing 33 is formed in a bowl shape, and can store lubricating oil.

Next, the operation of the scroll compressor 1 will be described.
When the drive motor 20 of the scroll compressor 1 is driven, the rotating shaft 23 rotates, and the movable scroll 12 fitted on the eccentric shaft 232 of the rotating shaft 23 turns with respect to the fixed scroll 11. When the orbiting scroll 12 orbits with respect to the fixed scroll 11, low-pressure refrigerant is sucked from the outside of the casing 30 into the space surrounded by the fixed scroll 11 and the movable scroll 12 via the suction portion 35. Then, the refrigerant is compressed as the volume of the compression chamber 15 changes. The high-pressure refrigerant compressed in the compression chamber 15 flows out below the compression unit 10.

  The high-pressure refrigerant that has flowed below the compression unit 10 is discharged to the outside of the casing 30 via a discharge unit 34 provided in the casing 30. In the process of being discharged to the outside of the casing 30, the gas flows through a gap between the rotor 22 and the stator 21 and a gap between the stator 21 and the central casing 31. Then, the high-pressure refrigerant discharged to the outside of the casing 30 is sucked again from the suction portion 35 after the respective steps of condensation, expansion, and evaporation in the refrigerant circuit.

  On the other hand, the lubricating oil accumulated in the lower casing 33 of the casing 30 is pumped up by the pump 243 and rises through the through hole 233 formed in the rotating shaft 23. The raised lubricating oil is supplied to each bearing of the rotating shaft 23 through the first communication hole 234, the second communication hole 235, and the third communication hole 236 formed in the rotating shaft 23, Or 10 sliding parts. The lubricating oil supplied to the sliding portion of the compression section 10 and the lubricating oil supplied to the bearing of the rotating shaft 23 through the second communication hole 235 and the third communication hole 236 are formed on the frame 13. It returns to the lower casing 33 through the communication holes 131e and the grooves 131d, the gap between the rotor 22 and the stator 21, and the axial hole formed in the support member 24, and accumulates in the lower portion of the casing 30. . In this process and in the process in which the high-pressure refrigerant flows through the gap between the rotor 22 and the stator 21 before being discharged to the outside of the casing 30, the lubricating oil and the refrigerant cool the drive motor 20 while cooling the drive motor 20. Flows to The lubricating oil circulated with the high-pressure refrigerant is then separated from the refrigerant and accumulates in a lower portion of the casing 30.

Incidentally, such a scroll compressor 1 may be equipped with a slide bush mechanism. The slide bush mechanism is a mechanism that improves the sealing effect (adhesion effect) by pressing the movable scroll 12 against the fixed scroll 11 using the compression load of the gas that is the refrigerant sucked from the through hole 111a.
On the other hand, in recent years, as a wide range is required, it is required that the rotation speed of the rotating shaft 23 can be set widely from a low speed to a high speed.
However, in the existing slide bush mechanism, when the rotation speed of the rotating shaft 23 increases, an excessive pressing force of the movable scroll 12 against the fixed scroll 11 is generated due to the influence of the centrifugal force. Therefore, the existing slide bush mechanism cannot be mounted on the scroll compressor 1 in which the rotation speed of the rotating shaft 23 is variable.
Therefore, in the present embodiment, a new slide bush mechanism that operates the slide bush mechanism when the rotation speed of the rotation shaft 23 is low, and prevents an excessive pressing force from being generated when the rotation speed of the rotation shaft 23 is high. 40 realizes the scroll compressor 1 that can exert the sealing effect only when the rotation speed of the rotating shaft 23 is low.

FIG. 2 is a top view of the slide bush mechanism 40. FIG. 2 shows the inside of the casing 30 of the scroll compressor 1 of FIG. 1 when the compression unit 10 is removed and viewed from above.
As illustrated, the slide bush mechanism 40 includes a slide bush 41 and an inner bush 42 on a main shaft 231 of the rotating shaft 23. The slide bush 41 is provided on the outermost periphery of the eccentric shaft 232 of the rotating shaft 23 and is an example of a first bush fitted to a bearing of the movable scroll 12. The inner bush 42 is provided between the slide bush 41 and the eccentric shaft 232, and is an example of a second bush in which the eccentric shaft 232 is fitted.

  The slide bush 41 has a slide surface 411, and the inner bush 42 has a slide surface 421. The slide bush 41 rotates according to the rotation of the inner bush 42 when the slide surfaces 411 and 421 come into contact with each other on a vertical plane. For example, the slide bush 41 and the inner bush 42 rotate around the eccentric shaft 232 without shifting in the circumferential direction. However, the inner bush 42 has a protrusion 422, and the rotation thereof is restricted by hitting the stoppers 232 a and 232 b of the eccentric shaft 232. On the other hand, by providing a gap between the slide bush 41 and the inner bush 42, the slide bush 41 can slide along the slide surfaces 411, 421 with respect to the inner bush 42. For example, the slide bush 41 and the inner bush 42 can be shifted in the direction of the gap along the slide surfaces 411 and 421. In the following, when simply referred to as “bush”, it means a member in which the slide bush 41 and the inner bush 42 are combined.

Here, as illustrated, in the top view of the slide bush mechanism 40, the center of the main shaft 231 is set to a point O, the center of the eccentric shaft 232 is set to a point E, and the center of gravity of the bush is set to a point G. It is assumed that the point G is at a position delayed in the rotation direction of the rotation shaft 23 from the straight line connecting the points O and E. Further, a length of a line OG and r, the length of the line segment EG and G _r, the angle formed by the line segment OG and φ the point O with respect to the horizontal left direction of the line segment of the street view, the point E And the angle formed by the line segment EG with the line segment in the horizontal left direction in the figure is θ (φ, θ are positive clockwise).

In addition, a torque load is applied to the bush by two types of torques other than the compression load and the centrifugal load. One of the two types of torque is a first torque (hereinafter, referred to as “bearing torque T _sh ”) generated by rotation of the cylindrical portion 123 (see FIG. 1) of the orbiting scroll 12. The other of the two types of torque is a second torque (hereinafter, referred to as “centrifugal force torque T _c ”) generated by a centrifugal force (indicated by a white arrow in the drawing) acting on the center of gravity of the bush. is there.

Next, switching of the state of the slide bush mechanism 40 when the rotation speed of the rotating shaft 23 changes from low to high will be described.
FIG. 3A shows the state of the slide bush mechanism 40 when the rotation speed of the rotating shaft 23 is low. In this case, since the bearing torque _Tsh is larger than the centrifugal force torque _Tc , the protrusion 422 of the inner bush 42 stabilizes in a state in which it contacts the stopper 232a of the eccentric shaft 232. That is, it is stabilized at θ = −45 °. In this state, the load of the movable scroll 12 due to the gas pressure and the centrifugal force (hereinafter referred to as “movable scroll load F _Total ”) causes the slide bush 41 to move in the direction in which the amount of eccentricity increases along the slide surface 411 (indicated by a broken arrow). The movable scroll 12 is pressed against the fixed scroll 11. Hereinafter, the position of the inner bush 42 in this state is referred to as “position 1”. This position 1 is a position where the slide bush mechanism 40 has the same structure as the existing slide bush mechanism. The state of FIG. 3A is an example of a state other than the predetermined state in which the inner bush 42 has rotated around the eccentric shaft 232 to a predetermined angle.

FIG. 3B shows a state of the slide bush mechanism 40 when the rotation speed of the rotation shaft 23 is increased. In this case, since the centrifugal force torque _Tc becomes larger than the bearing torque _Tsh , the bush rotates along the eccentric shaft 232 until the protrusion 422 of the inner bush 42 contacts the stopper 232b of the eccentric shaft 232. Thereby, the amount of eccentricity of the slide bush 41 is fixed, and the slide bush 41 is not affected by the centrifugal force on the bush or the movable scroll load. Here, the direction indicated by the dashed arrow is an example of a predetermined direction in which the slide bush 41 can slide so that the amount of eccentricity is reduced by the load on the movable scroll 12. Hereinafter, the position of the inner bush 42 in this state is referred to as “position 2”. This position 2 is a position where the slide bush mechanism 40 has the same structure as the fixed crank structure. The state in FIG. 3B is an example of a predetermined state in which the inner bush 42 has rotated around the eccentric shaft 232 to a predetermined angle, and 90 ° is used as an example of the predetermined angle.

  Also, here, the two states of FIGS. 3A and 3B are shown as the states of the slide bush mechanism 40, but the present invention is not limited to this. For example, the state of the slide bush mechanism 40 may be three or more states. That is, as the state of the slide bush mechanism 40, at least two states in which each state rotates around the eccentric shaft 232 to an angle corresponding to each state may be used.

Next, switching of the state of the slide bush mechanism 40 will be described in more detail.
First, the bearing torque _Tsh and the centrifugal force torque _Tc are represented by the following equations (1) and (2), respectively.

Here, m indicates the mass of the bush, D indicates the diameter of the slide bush mechanism 40, L indicates the height of the slide bush mechanism 40, and η indicates the viscosity of the lubricating oil supplied to the bearing of the eccentric shaft 232. C indicates the bearing radial gap (the length obtained by subtracting the radius of the slide bush 41 from the radius of the bearing of the eccentric shaft 232), and ω indicates the rotation speed of the rotary shaft 23. Further, as shown in FIG. 2, r is the length from the center O of the spindle 231 to the center of gravity G of the bush, G _r is the length from the center E of the eccentric shaft 232 to the center of gravity G of the bush, phi Is an angle indicating the direction from the center O of the main shaft 231 to the center of gravity G of the bush, and θ is the angle indicating the direction from the center E of the eccentric shaft 232 to the center of gravity G of the bush.

As can be seen from the above equations (1) and (2), the bearing torque T _sh and the centrifugal force torque T _c both increase as the rotation speed of the rotating shaft 23 increases, but the former is a linear function of the rotation speed. And the latter has the characteristic difference that it varies with a quadratic function of the rotational speed.

FIG. 4 is a graph showing changes in the bearing torque _Tsh and the centrifugal force torque _Tc when the rotation speed of the rotating shaft 23 changes. The thin line indicates a change in the bearing torque _Tsh , and the thick line indicates a change in the centrifugal torque _Tc . Here, the center of gravity G when theta is changed in FIG. 2 since rotates about the E while maintaining a constant G _r, r and φ is a value that depends on theta. Since there is no θ, r, or φ on the right side of equation (1), the bearing torque _Tsh is constant regardless of θ, but since there are both θ, r, and φ on the right side of equation (2), the centrifugal force is The torque _Tc differs depending on θ. Therefore, FIG. 4 shows the change in the centrifugal force torque _Tc with respect to −45 ° which is the lower limit value of θ and 45 ° which is the upper limit value of θ. The solid line is the centrifugal torque _Tc when θ = −45 °, and the broken line is the centrifugal torque _Tc when θ = 45 °. As can be seen from the graph shown by the thick solid line in FIG. 4, when the rotation speed becomes higher than about 60 (rps), the centrifugal force torque _Tc becomes larger than the bearing torque _Tsh , and the bush moves along the eccentric shaft 232. When rotated, the position is switched from position 1 to position 2. Here, about 60 (rps) is an example of a predetermined rotation speed or a rotation speed when the magnitude relationship between the bearing torque _Tsh and the centrifugal force torque _Tc is reversed. Conversely, as can be seen from the graph shown by the thick broken line in FIG. 4, when the rotation speed becomes lower than about 45 (rps) from the high speed state, the centrifugal force torque _Tc becomes smaller than the bearing torque _Tsh , and Switches from position 2 to position 1. In this case, the upper limit value and the lower limit value of θ and the number of rotations when the position 1 and the position 2 are switched are design items and may be changed as designed.

Next, a modified example of the slide bush mechanism 40 according to the present embodiment will be described.
From the above equation (2), the centrifugal force torque T _c is seen to be dependent on the length G _r from the center E of the eccentric shaft 232 to the center of gravity G of the bush. Therefore, by adjusting the position of the center of gravity G of the bush, the magnitude of the centrifugal force torque _Tc can be adjusted.

FIG. 5 is a top view of a first modification of the slide bush mechanism 40. FIG. FIG. 5 also shows the inside of the casing 30 of the scroll compressor 1 of FIG. 1 when the compression unit 10 is removed and viewed from above.
The first modified example of the slide bush mechanism 40 includes a slide bush 41 and an inner bush 42, and further includes a switching weight 423 connected to the inner bush 42. In the first modification, the position of the center of gravity G of the bush is adjusted by providing the switching weight 423. Although the switching weight 423 is connected to the inner bush 42 as described above, a through hole is provided in a portion near the upper surface of the main shaft 231 below the slide bush 41 and extends to the outside of the slide bush 41 through the through hole. It is good to arrange. This through-hole may be shaped so as not to hinder sliding along the slide surface 421 of the slide bush 41. Further, it is preferable that the height of the cylindrical portion 123 of the movable scroll 12 is shortened by the height of the switching weight 423 so that the rotation of the movable scroll 12 is not hindered by the switching weight 423. Alternatively, the switching weight 423 may be connected to the slide bush 41. In this sense, it can be said that the switching weight 423 is an example of a protrusion connected to at least one of the slide bush 41 and the inner bush 42 for adjusting the center of gravity.

FIG. 6 is a top view of a second modification of the slide bush mechanism 40. FIG. FIG. 6 also shows the inside of the casing 30 of the scroll compressor 1 of FIG. 1 when the compression unit 10 is removed and viewed from above.
The second modification of the slide bush mechanism 40 includes a slide bush 41 and an inner bush 42, and the slide bush 41 is provided with a switching hole 413. In the second modification, the position of the center of gravity G of the bush is adjusted by providing the switching hole 413. Alternatively, the switching hole 413 may be provided in the inner bush 42. In this sense, it can be said that the switching hole 413 is an example of a concave portion provided on at least one of the slide bush 41 and the inner bush 42 for adjusting the center of gravity.

  As described above, in the present embodiment, when the rotation speed of the rotation shaft 23 increases, the slide surface between the slide bush 41 and the inner bush 42 is slid so that the eccentric amount is reduced by the load on the movable scroll 12. By arranging the bush 41 in a predetermined slidable direction, the amount of eccentricity of the movable scroll 12 from the main shaft 231 is suppressed. As a result, it is possible to suppress the generation of an excessive pressing force of the movable scroll 12 against the fixed scroll 11 when the rotation speed of the rotating shaft 23 becomes high.

  In the present embodiment, when the rotation speed of the rotating shaft 23 increases, the amount of eccentricity of the movable scroll 12 from the main shaft 231 is suppressed. However, this is broader, and it may be considered that when the rotation speed of the rotating shaft 23 increases, the pressing force of the movable scroll 12 against the fixed scroll 11 is suppressed. Furthermore, it may be considered that the pressing force of the movable scroll 12 against the fixed scroll 11 is changed according to the rotation speed of the rotating shaft 23.

  Here, when the rotation speed of the rotary shaft 23 becomes high, the amount of eccentricity of the orbiting scroll 12 from the main shaft 231 is suppressed, as described in the present embodiment when the rotation speed of the rotary shaft 23 is low. Includes an aspect of increasing the amount of eccentricity of the movable scroll 12 from the main shaft 231 and fixing the amount of eccentricity of the movable scroll 12 from the main shaft 231 when the rotation speed of the rotating shaft 23 is high. . In addition, when the rotation speed of the rotating shaft 23 becomes high, the pressing force of the orbiting scroll 12 against the fixed scroll 11 is suppressed, as described in the present embodiment when the rotation speed of the rotating shaft 23 is low. Means that the movable scroll 12 is pressed against the fixed scroll 11 and the movable scroll 12 is not pressed against the fixed scroll 11 when the rotation speed of the rotating shaft 23 is high.

DESCRIPTION OF SYMBOLS 1 ... Scroll compressor, 11 ... Fixed scroll, 12 ... Movable scroll, 23 ... Rotating axis, 231 ... Main axis, 232 ... Eccentric axis, 232a, 232b ... Stopper, 40 ... Slide bush mechanism, 41 ... Slide bush, 411,421 ... Sliding surface, 413 ... Switching hole, 42 ... Inner bush, 422 ... Protrusion, 423 ... Switching weight

Claims (13)

A fixed scroll fixed in the housing,
A movable scroll that rotates while being engaged with the fixed scroll;
A rotating shaft for turning the movable scroll, supported by an eccentric shaft eccentric from the main shaft,
Pressing the movable scroll against the fixed scroll is provided between the bearing of the movable scroll and the eccentric shaft, and by changing the sliding direction when a gas load is applied according to the rotation speed of the rotating shaft. A scroll compressor comprising a slide bush mechanism for changing a force.   The scroll compressor according to claim 1, wherein the slide bush mechanism suppresses a pressing force of the movable scroll against the fixed scroll when a rotation speed of the rotation shaft increases.   The scroll compressor according to claim 2, wherein the slide bush mechanism suppresses the pressing force by suppressing an eccentric amount of the movable scroll from the main shaft.   The slide bush mechanism suppresses the amount of eccentricity by using a first bush fitted to the bearing of the movable scroll and a second bush fitted to the eccentric shaft. The scroll compressor according to claim 3, wherein The first bush is slidable along a slide surface between the first bush and the second bush,
The slide bush mechanism suppresses the amount of eccentricity by directing the slide surface in a predetermined direction in which the first bush can slide so that the amount of eccentricity is reduced by a load on the movable scroll. The scroll compressor according to claim 4, wherein: The first bush rotates according to the rotation of the second bush,
The scroll compression according to claim 5, wherein the second bush turns the slide surface in the predetermined direction when the second bush rotates to a predetermined angle around the eccentric shaft. Machine.   The predetermined state is at least two states of the second bush, and each state is one of at least two states rotated around the eccentric shaft to an angle corresponding to each state. The scroll compressor according to claim 6, wherein:   The second bush switches from a state other than the predetermined state of the at least two states to the predetermined state when a rotation speed of the rotation shaft exceeds a predetermined rotation speed. Item 8. A scroll compressor according to Item 7.   In the predetermined rotation speed, the magnitude relationship between the first torque generated by rotation of the bearing of the orbiting scroll and the second torque generated by centrifugal force on the first bush and the second bush is reversed. The scroll compressor according to claim 8, wherein the rotation speed is at that time. The first torque changes as a linear function of the rotation speed of the rotation shaft,
The scroll compressor according to claim 9, wherein the second torque changes as a quadratic function of a rotation speed of the rotation shaft.   The center of gravity of the first bush and the second bush is located at a position delayed in a rotation direction of the rotary shaft from a straight line connecting a center of the main shaft and a center of the eccentric shaft. 6. The scroll compressor according to 5.   The scroll compressor according to claim 11, further comprising a protrusion connected to at least one of the first bush and the second bush for adjusting the center of gravity.   The scroll compressor according to claim 11, wherein a recess for adjusting the center of gravity is provided in at least one of the first bush and the second bush.