JPH03249386A - Method and device for reducing bearing load in scroll compressor - Google Patents

Abstract

PURPOSE: To minimized the supporting bearing load by providing a support, a fixed scroll element fixedly installed in the support, and a track-revolving scroll element which revolutes in a track in relation to the fixed scroll element which limits at least one compression space. CONSTITUTION: A main fixed component of a scroll compressor 10 is made up of a support, or a housing 11 and a fixed scroll 12, and a moving component of the compressor 10 comprises a track-revolving scroll element 13, and a crankshaft 14 having a main part 15 aligned with the axis and an eccentric crank 17. The eccentric crank 17 is aligned with an eccentric shaft 18, and acts on the element 13 supported by the shaft 18. Further, the moving component comprises the upper-and lower part counter weights 20, 21 in the positions indicated on the drawing, and a drive shaft 14 is supported by supporting bearings 22, 23 to be rotated around the axis 16. Furthermore, the drive shaft 14 is rotated-driven by a motor-rotor making interface with a motor stator 25.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates generally to compressors, and more particularly to scroll compressors.

[Prior Art] There are already known compressors of various configurations, among which the so-called scroll or scroll type vapor compressor is particularly used for air conditioning equipment, especially in the range of 1 to 10 tons of cooling capacity. compressors are becoming increasingly popular. Among the characteristics that make such scroll compressors more attractive for many applications than reciprocating compressors are their high efficiency, reduced number of moving parts, low noise and low vibration. . An example of a scroll compressor of the type in question is disclosed, for example, in U.S. Pat. No. 4,715,796.

The main components of a typical scroll vapor compressor include a sump housing and a normally configured support, a fixed scroll element and an orbiting scroll element, an eccentric crank section, and are attached to a rotating support by respective support bearings. and a drive motor for rotating the drive shaft about an axis such that the orbiting scroll element performs an orbiting motion relative to the fixed scroll element by means of a crank portion, the orbiting element being any known. By means of a suitable coupling device of construction, rotation with the drive shaft is prevented, while still allowing the desired orbiting movement to take place. Vapor compression is arranged in at least one compression space bounded by the stationary and orbiting scroll elements, when the orbiting scroll elements are driven by an eccentric crankshaft section, and the pressure of the medium to be compressed is It acts on both the element and the orbiting scroll element. As a result of the rotation, and in particular the eccentric and orbital movements of the various structural 55 elements, and also the forces associated with the compression process, loads are transmitted to the drive roller and reacted by the support bearings. In an attempt to reduce vibration and bearing loads, it has been proposed to provide each drive shaft with a counterweight for co-rotation with the drive shaft.

SUMMARY OF THE INVENTION In previously proposed scroll compressors where the drive shaft axis is typically vertically oriented and the scroll element is mounted on top during operation, this mounting The upper counterweight as described above is located axially close to the crank position and circumferentially one inch away from the crank position.
They are mounted 80 degrees apart, while the lower counterweight is much smaller than the upper counterweight and is circumferentially aligned with the crank section.

Therefore, balancing of existing scroll compressors appears to follow the practices typically used for reciprocating compressors where only inertia forces are considered when sizing and positioning. This approach is effective for reciprocating compressors because the pressure component of the resultant force vector used for the crank varies greatly in magnitude and also varies somewhat in the direction relative to the crank, so it is not dynamically balanced. Experience has shown that this approach results in unnecessarily much higher support shaft loads.

The general problem of the invention is therefore to avoid the disadvantages of the prior art.

More particularly, it is an object of the invention to provide a scroll compressor which does not have the disadvantages of the various known compressors.

Yet another object of the invention is to develop a Kaflor compressor of the type in question in such a way that the support bearing loads of the rotary drive shaft are reduced under operating conditions.

Still another object of the invention is to design a scroll compressor of the above type in such a way that it is relatively simple to construct, inexpensive to manufacture, easy to use and yet reliable in operation. That's true.

A companion object of the present invention is to devise a method for balancing a compressor of the type described above from a crankshaft-mounted collar in such a way as to minimize support bearing loads.

Means for Solving the Problems According to these problems and the problems that will become apparent from the following description, one feature of the present invention is to include a support, a fixed scroll element fixedly attached to the support, and a fixed scroll element fixedly attached to the support. A scroll compressor comprising an orbiting scroll element orbiting relative to the scroll element and confining therewith at least one compression space. a drive shaft having a main portion centered on the axis, an eccentric crank portion laterally offset from the axis, and a crank portion comprising an orbiting scroll; bearing means for supporting the annular portion on the support for rotation about the axis to act on the element; and means for rotating the drive shaft about the axis to effect an orbiting movement by the orbiting scroll element. and a resultant pressure is concomitantly applied to the orbiting scroll element by the medium. According to the invention,
Further, the bearing means is mounted on a drive shaft that rotates together about an axis, and at least when the drive shaft rotates at a predetermined speed, substantially eliminates the combined effect of other eccentric masses and the resultant pressure force on the bearing means. Balancing means are provided having respective masses and angular distributions about the axis such as to compensate for this.

According to another aspect of the invention, a fixed scroll element is fixedly mounted on the support and an orbiting scroll element is supported in respective bearings on the support for rotation about an axis. The eccentric crank portion of the drive shaft provides an orbiting movement relative to the fixed scroll element, the fixed scroll element and the orbiting element delimiting at least one compression space, so that the medium to be compressed in the compression space is A method is provided for balancing a scroll compressor in which a scroll compressor applies a pressure resultant force to an orbiting scroll element. The method of the invention includes at least one of the drive shafts.
measuring the magnitude and direction of the pressure resultant force and all inertia forces of the eccentric mass at one rotational speed, and determining the combined effect of the resultant pressure and inertia force on the bearing during rotation of at least the drive shaft at one speed; calculating the masses and positions of at least two counterweights to be mounted on the co-rotating drive shafts together about their axes so as to substantially compensate, and so on at the calculated positions on the co-rotating drive shafts; The method includes the step of installing a counterweight having a mass calculated as follows.

The invention is based on the recognition of the fact that the above-described approaches to counterweights, which are suitable for reciprocating compressors, are not suitable for use with scroll compressors. This is because a detailed analysis of the pressure generated in a scroll compressor shows that the pressure component of the resultant force vector acting on the crank part of the drive shaft is relatively constant in magnitude and direction with respect to the crank part (the direction of the vector is (rotating with the crank angle at an almost constant relative angle to the crank). Therefore, the pressure component acts in a similar manner to the inertial force. Therefore, consideration and should be taken when sizing and positioning the counterweight during compressor dynamic balancing in accordance with the present invention.

[Example] Refer to the drawings in detail. Referring first to FIG. 1 thereof, it will be seen that the reference numeral 10 is used to indicate a typical construction of a scroll compressor suitable for use in the present invention. Scroll compressor 10 is illustrated in a substantially simplified manner, however, without omitting all features necessary for understanding the invention. The support or housing 11 and the fixed scroll 12 form the main fixed structure 55 of the scroll compressor 10.
．． constitutes an element. On the other hand, the motion mechanism 55 element of the scroll compressor 10 is
g) scroll element 13 and main part 1 aligned with the axis;
5 and a flank shaft 14 having an eccentric flank 17, said eccentric flank 17 being laterally offset with respect to the main portion 15, aligned with an eccentric shaft 18, and supported by a scroll bearing 18. This acts on the orbiting scroll element 13. Such a main movement mechanism 1i32 element furthermore has the upper counterweight 20 in question in the position shown, which is the continuous position of the scroll compressor 1o.
and a lower counterweight 21.

The drive shaft 14 is supported for rotation about an axis 16 by an upper shaft or support bearing 22 and a lower shaft or support bearing 23, and, in the illustrated exemplary configuration of the scroll compressor 10, a support or housing. 11 and is rotationally driven by a motor rotor interfacing to a motor stator 25, which is shown fixed thereto.

The orbiting movement of the orbiting scroll 13 results in various forces to be generated. The vectors of these forces are shown in the top plan view of FIG. 2a, and correspondingly also in the second brl.
! Shown in side elevation of J. The radial, tangential and axial pressure forces Fpr, Fpt and Fpa are generated by the steam pressure on the orbiting rolls 13. The radial and tangential pressure loads Fpr and Fpt can be calculated for all angles θ by the following formulas: Fpr (θ) −2ha CP, −Psc) (
1) 4 [Pi-Pi+1] + (2πN-〇) [PN-
Psc] (2) In this case, the above symbols have the following meanings.

Fpr Pressure force in the radial direction due to the orbiting scroll Fpt Pressure force in the tangential direction due to the orbiting scroll h Scroll wrap height a Base circle radius P1 of the scroll involute...
PN Pressure in the scroll compression pocket Psc Pressure in the suction chamber surrounding the orbiting scroll N Number of paired compression pockets at the start of sealed compression) θ Crank angle i Exponential radial and tangential inertia of the paired scroll compression pockets The forces F isc and Fit are due to the angular acceleration and centripetal acceleration of the orbital turn 13, respectively;
These are calculated using the following formula.

Fisc=msc yse w2 (3)Fi
t=msc yse w In this case the above symbols have the following meanings: Fis
c Radial inertia (centrifugal) force of the orbiting scroll Fit Radial inertia force of the orbiting scroll msc
Mass of the orbiting scroll ysc Radius from the axis of the crankshaft to the axis of the orbiting scroll W Angular velocity of the crankshaft W Angular acceleration of the crankshaft In general, the vapor compressor is and the speed of the scroll compressor varies slightly in its operating conditions;
Angular acceleration is typically very low. Therefore, Fit can be ignored.

During the operation of the scroll compression 8!10, the reaction force to the above-mentioned overcurrent is as shown in Figs. 2a and 2bfm by the resultant force vector Fsbc, which is shown in more detail by monitoring the angular position in 3aQU. is generated in the orbiting scroll element bearing 19. Figure 3b shows that the magnitude of the resultant force Fsbc generated by the orbiting scroll 13 of a typical scroll compressor lO is only 25% of the average force.
It has a peak-to-peak variation of , indicating that it is relatively constant. More importantly, the crank part 17
The relative angle between the resultant force Fsbc and the resultant force Fsbc is almost constant. This resultant force Fsbc generated by the motion of the orbiting roll 13 therefore acts in a similar manner to an inertial force in that it is of almost constant magnitude and rotates with the crank part 17.

In FIG. 4, the resultant force Fsbc generated by the orbiting scroll motion sustains the motion components described above in connection with FIG. It is shown diagrammatically to affect the The schematic diagram in FIG. 4 shows the crank part 1
7. A small center of mass circle is used to indicate the relative positions of the upper counterweight 20, lower counterweight 21, and motor rotor 24. The centers of bearings 22 and 23 are also indicated by small circles.

In order to arrive at the required inertia force and counterbalance 20 and 21 positions with zero reaction in the bearings 22 and 23, force and moment balancing can be performed on the crankshaft 14 using FIG.

For this reason, the forces in bearings 22 and 23 are not shown in FIG. Any inertial force due to motor rotor eccentricity is ignored as it is very small.

The above force and moment balance (compensating for both pressure and inertia forces) required for correct sizing and positioning of the counterweights 2° and 21 using the method of the invention is obtained from the equations below.

Σpz=Q=Ficrcosθ+F sbc cos
(θ−φ)+F cwv cos (θ+ψcwv)
+F cwl cos(θ+ψcwl) ΣFy=O=-Ficr sinθ-F 5sbc 5
in(θ−φ) −Fcwv sin (θ+ψcwv
)Fcwl sin (θ+ψcwl) ΣMx=O= [Ficr sinθ+Fsbcsi
n(θ-φ)] (Z + 10 Z2+ Z3+ Z4) + FCWV 5
in(θ+φcwv) (Z2+Z3+Z4)Emy
=O= [Ficr cosθ+F sbc c
osφ(θ−φ)] (Z, + Z2+ Z3+ Z,) +Fcwv c
os(θ0φcwv) (Z 2+ Z s0Z <
) If this is transformed, S1 mouth φ Fcwv = Fsbc sin ψcwv φcwl-ψc w v + R Zl + Z2 + Z3 + Z4 Length W shown in Figure 1
eyl Lower counterweight phase angle Wcwv
Upper Counterweight Phase Angle An example of the results obtained when using the method of the invention is shown in FIG.

In this case, the position and inertia of the counterweights 20 and 21 are plotted against the crank angle. Fifth
The figure shows that the magnitude of the inertial force is particularly large for the lower counterweight 2.
1 and clearly shows that the angular position relative to the crank is almost constant. Therefore, if the average values of inertial force and angular position are
The counterweights 20 and 21 of the present invention are ideal for dual-basis fishing without the need for additional complexity when these designs are superior to conventional counterweights. , replace conventional counterweights, i.e., these counterweights are located in the same axial region of the drive shaft 14 as conventional counterweights, and only their size and angular position differ from that of the upper counterweights. As shown in FIG. 6 of the drawings for 20, it differs from conventional counterweights.

Accordingly, as noted above, the present invention relates to an improved approach to balancing the radial and tangential loads generated on scroll vapor compressor 10. This technique is
A counterweight 2 is placed on the drive shaft 14 so that the resultant loads imparted by both the compression stroke and the moving scroll element 13 are largely offset by the drive shaft support bearings 22 and 23.
Including sizing and positioning 0 and 21.

The combination is a counterweight 20, which is larger than a conventional counterweight (designated 20');
and is positioned at a crank angle of 180 degrees or less.

On the one hand, the bearing loads calculated using the conventional balancing method and the balancing method proposed by the present invention are shown in FIG. 7 for a compressor speed of 3600 RPM. As shown, the method of the present invention results in much lower bearing loads than prior art approaches. Lower bearing loads also translate directly into increased reliability and longevity of existing scroll compressors. As a result, expensive bearings (roller bearings) used in existing scroll compressors can be replaced by lower cost bearings (such as journal bearings) while maintaining or improving compressor reliability and lifespan. I can do it.

For constant speed compressors, the counterweights used according to the invention are less complex than those currently used. (i.e. fixed weight and position) - However, the size and position of the counterweight are different as shown in FIG.

On the other hand, for a variable speed compressor, the force and position of the respective counterweight 20 and/or 21 as the speed is varied to achieve the characteristics shown in Figures 8a and 8b. Contains mechanisms for effective change. Such a mechanism is a relatively simple passive device, as conceptually shown in FIG. It is shown as having a recess 30 for slidingly receiving the .

It will be appreciated that as the rotation of the shaft 14 increases, the counterweight 31 is increasingly displaced out of the recess 30 by the centrifugal force acting against the force of the tension spring 33, and the inertial force exerted thereby increases accordingly. There will be.

Another method of implementing the above mechanism is shown in FIG. In this case, the counterweight element 33 is mounted on the counterweight 20 in such a way that it can pivot about a pivot axis 34 as acted by a clockwise twisting spring, as shown in the figure. This again,
As the rotational speed increases, the counterweight member 33 displaces the counterweight member 33 outwardly, but this time in a counterclockwise direction, around the pivot 34 against the biasing action of the spring 35. The spring 35 and the counterweight 20 are displaced by the counterweight 33, and the accompanying increase in inertia force is caused by the rotation of the spring 35 and the counterweight 20.
It is finally applied to the shaft 14 via the upper pivot 34. Obviously, the mass, circumferential position and trajectory of movement of the speed-sensitive counterweight members 30 and 31 will depend on the compressor, such as the weight of the orbiting scroll element 13, the arrangement of the counterweights 20 and 21, and the operating speed range. Very dependent on design parameters.

Regardless, once the other parameters of the variable speed scroll compression 8!10 are known, the parameters of the counterweight member are easily calculated. This variable shape (ge
The additional complexity of the counterweight 30 is easily justified for low bearing loads over a wide speed range.

Although the invention has been illustrated and described as being implemented in a particular configuration of a scroll compressor, the invention is not limited to this particular embodiment; rather, the scope of protection of the invention is limited solely to the accompanying It should be determined by the claims.

[Brief explanation of drawings]

1 is a somewhat simplified axial cross-sectional view of a type of scroll compressor suitable for use in the present invention, FIGS. 2a and 2.
Figure b is a schematic plan view and side elevation view, respectively, of the scroll element of the pressing force of Figure 1, showing in vector form the various forces acting on the scroll element; Figure 3a is a reference; A graphical representation of one vector of tlE2arllJ showing the spatial relationship with respect to the frame; Figure 3b is the angular position of the crank position of Figure 1 and Figure 3a
4 is a graphical representation of the magnitude of the vector shown in the figure and its relationship to the angle; FIG. FIG. 5 is a graph of the relationship between the crank angle and the ideal counterweight force and angular position. FIG. 6 is a graph of the relationship between the crank angle and the ideal counterweight force and angular position. 7 is a graphical representation of support bearing loads obtained using the present invention as compared to loads encountered by the prior art; FIGS. 8a and 8b are drive A graphical representation of the relationship between the rotational speed of the shaft and the desired angle and force of each counterweight, Figure 9 is a diagram similar to Figure 6, but Figures 8a and 8.
Figure 10 is a diagram similar to Figure 8, but showing a modified configuration of the adjustable counterweight; be. 3 ((Tani C FIG, 8α FIC lower 2?.

Claims (9)

[Claims] (1) a support; a fixed scroll element fixedly attached to the support; attached for orbital movement relative to the fixed scroll element, and defining at least one compression space together with the fixed scroll element; a confining orbiting scroll element; means for admitting a medium to be compressed into said compressor space and for discharging said medium from said compression space; a main portion centered on an axis; and means for discharging said medium from said compression space; a drive shaft having an eccentric crank portion offset to; supporting the main portion of the shaft on the support for rotation about the axis so that the crank portion acts on the orbiting scroll member; bearing means for rotating said drive shaft about said axis and causing said orbiting scroll element to effect said orbital motion, provided that said medium is compressed in said compression space before discharge thereof; and at least two counterweights, each mounted to the drive shaft for rotation therewith about the axis, wherein a resultant pressure is incidentally applied to the orbiting scroll element by the medium. and each such that at least when said drive shaft is rotating at a predetermined speed, substantially compensates for the combined effects of all other eccentric masses and said resultant pressure force on said bearing means. Scroll compressor characterized in that it comprises a balancing means having a mass and an angular position about said axis. (2) the bearing means includes at least two bearings spaced axially along the main portion of the drive shaft, and each of the two counterweights is positioned at a different bearing point of the bearing; The scroll compressor according to claim 1, wherein: (3) the balancing means: at least one counterweight member mounted to rotate with the drive shaft about the axis and also move along a predetermined path relative to the drive shaft; a counterweight member is displaceable along the path from one position to another position by the rotational speed of the drive shaft by centrifugal force applied to the counterweight member during rotation of the drive shaft; means for elastically pushing the counterweight member into a predetermined position along the path; a force applied to the counterweight member by the pushing means;
A scroll compressor according to claim 1, wherein the mass of the counterweight member and the course of the path are such that the balancing effect of the balancing means is effective over a wide range of rotational speeds of the drive shaft. (4) The fixed scroll element is fixedly mounted on the support, and the orbiting scroll element is fixed for rotation about its axis by an eccentric crank portion of the drive shaft supported by respective bearings on the support. The fixed scroll element and the orbiting scroll element define at least one compression space, so that the medium compressed in the compression space is combined with the orbiting scroll element. A method of balancing a scroll compressor applying a pressure force, comprising: measuring the magnitude and direction of the resultant pressure force and an eccentric mass at at least one rotational speed of the drive shaft; at least one speed of the drive shaft; at least two motors to be mounted on said drive shaft for co-rotation with said drive shaft about said axis so as to each substantially compensate for the combined effect of said resultant pressure and inertial forces on a bearing during rotation at Calculate the mass and position of the counterweight. A method comprising the step of mounting a counterweight having said mass at said location on a drive shaft for co-rotation with the drive shaft. (5) a drive shaft having a support, a main portion aligned with the axis, and an eccentric crank portion laterally offset from the axis; bearing means supporting the main portion; fixed scroll means mounted to said support so as to be fixed thereto with respect to rotation at least about said axis; and fixed scroll means mounted for orbital movement relative to said fixed scroll element. and at least one
an orbiting scroll element confining a compression space and actuated by the crank portion of the drive shaft; means for admitting the medium to be compressed into the compression space and for discharging the medium from the compression space; means for rotating the drive shaft about the axis relative to the crank portion and causing the driven orbiting scroll element to effect the orbital orbit, provided that the medium is compressed in a compression space before ejection; at least two counterweights mounted on mutually opposite sides of the bearing means to the drive shaft for co-rotating with the drive shaft about the axis; , whereby the reaction inertia force applied to the drive shaft takes into account not only all inertia forces acting on the drive shaft, but also the force of the pressure on the counterweight, so that at least the drive shaft is Each of said counterweights has a mass and angular position about said axis so as to substantially compensate for the combined effects of all other eccentric masses and said resultant pressure forces on said bearing when rotating at speed. A scroll compressor, characterized in that it comprises a balancing means having: (6) Each of the counterweights is attached to the main counterweight member so as to move along a predetermined path with respect to the main counterweight member attached to rotate together with the drive about the axis. the auxiliary counterweight and the auxiliary counterweight member,
a predetermined position along said path such that centrifugal force acting on said drive shaft during rotation causes said drive shaft to be displaceable from said predetermined position to another position along said path depending on the rotational speed of said drive shaft; means for elastically pushing the auxiliary counterweight member, the force applied to the auxiliary counterweight member by the pushing means, the mass of the auxiliary counterweight member, and the course of the path, the balancing effect of the balancing means 6. The scroll compressor according to claim 5, wherein the scroll compressor is effective over a wide range of rotational speeds of the drive shaft. (7) a fixed scroll element is mounted to the support so as to be fixed relative to the support at least with respect to rotation about an axis of rotation; and an orbiting scroll element:
The fixed scroll element and the orbiting scroll element are arranged in orbiting motion relative to the fixed scroll element by an eccentric crank portion of the drive shaft supported by respective bearings on the support for rotation about an axis of rotation, and the fixed scroll element and the orbiting scroll element are arranged in at least one Scroll compressor balancing method in which the medium compressed in the compression space imposes a resultant pressure force on an orbiting scroll element, in which the resultant pressure force and at least one of the drive shafts measuring the magnitude and direction of the resultant pressure force of the orbiting scroll and the drive shaft and all the inertia forces of the eccentric mass at the rotational speed; the reaction inertia force exerted by the counterweight on the drive shaft is the of said combined pressure and inertial forces on the bearing during rotation of the drive shaft at at least said one speed, taking into account all inertial forces acting on the shaft as well as said pressure forces on said counterweight. Calculate the masses and positions of at least two counterweights to be mounted on the drive shaft, in axially opposite bearings, for co-rotation with the drive shaft about the axis of rotation, so as to substantially compensate for coupling effects. A method of balancing a scroll compressor, which includes: (8) the balancing means includes at least one counterweight member mounted to move along a predetermined path relative to the drive shaft around the axis; said counterweight member in a predetermined position along said path such that said counterweight member is displaceable from said one position to said other position along said path by the rotational speed of said drive shaft due to centrifugal force acting thereon during rotation; means for elastically pushing the counterweight, the force applied by the pushing means to the counterweight, the mass of the counterweight member and the course of the path, such that the balancing effect of the balancing means covers a wide range of rotational speeds of the entire drive shaft. 6. The scroll compressor according to claim 5, wherein a counterweight having the mass is provided at the position on the drive shaft so as to rotate together with the drive shaft. (9) at least one of said courses of said path in a peripheral direction;
9. A scroll compressor according to claim 8, wherein the portion deviates from the radial direction of the drive shaft.