KR20060044336A - Scroll compressor - Google Patents

Abstract

An object of the present invention is to reduce the loss associated with the back pressure adjustment for adjusting the pulling force of the fixed scroll and the revolving scroll.

Of the back pressure chamber 18 which is provided on the back of the swing scroll 8 which is rotatably opposed to the fixed scroll 7 and introduces an intermediate pressure between the discharge pressure and the suction pressure, and the outermost wrap 7e of the fixed scroll. Back pressure regulating valve which relieves fluid in the back pressure chamber to the suction chamber or the compression initial compression chamber via the communication path according to the difference between the suction pressure or the compression initial pressure introduced through the communication path 2f formed at the end and the pressure in the back pressure chamber. (2), the through-hole 1 which communicates the compression chamber 13 which does not communicate with the communication path 2f, and the back pressure chamber 18 is provided in the turning scroll 8, and the back pressure chamber 18 Relieving a part of the excess pressure of) into the compression chamber 13 reduces the compression loss due to re-expansion.

Fixed Scroll, Back Pressure Chamber, Wrap, Back Pressure Adjustment Valve, Slewing Scroll

Description

Scroll Compressor {SCROLL COMPRESSOR}

1 is a longitudinal sectional view of an entire scroll compressor of one embodiment of the present invention;

Fig. 2 (a) is a plan view of the turning scroll of one embodiment of the present invention, and (b) is a sectional view taken along the line B-B of (a).

FIG. 3 is a plan view showing a compression chamber constituted by the swing scroll and the fixed scroll in the embodiment of FIG. 2; FIG.

4 is a plan view of a fixed scroll of one embodiment of the present invention;

Fig. 5 is a longitudinal sectional view of a back pressure regulating valve of one embodiment of the present invention.

FIG. 6 is a graph showing the relationship between the back pressure and the suction pressure in the embodiment of FIG. 1; FIG.

<Explanation of symbols for the main parts of the drawings>

1: through hole

2: back pressure regulating valve

7: fixed scroll

7a, 8a: hard board

7b, 8b: wrap

7c, 8c: root

7e: outermost lap

8: turning scroll

13: compression chamber

14: suction port

15: discharge port

18: back pressure chamber

[Document 1] Japanese Unexamined Patent Publication No. 10-110688

The present invention relates to a scroll compressor.

The scroll compressor arranges the fixed scroll and the rotating scroll which are formed by setting up spiral wraps on the hard board, respectively, by engaging the wraps with each other, and turning the rotating scrolls to sequentially rotate the volumes of the plurality of compression chambers formed between the wraps. By shrinking, the fluid is compressed. This compression action generates an axial force (hereinafter referred to as pushing force) to push the fixed scroll and the swing scroll. When both scrolls are pushed out, a gap is created between the end of the wrap and the hard plate, and the sealability of the compression chamber is deteriorated and the efficiency of the compressor is lowered. Therefore, a back pressure chamber is formed on the back surface of the rotating plate of the swing scroll, and the back pressure chamber is introduced with the intermediate pressure between the discharge pressure and the suction pressure of the compressor as the back pressure to press the swing scroll to the fixed scroll side by the back pressure, and to push out the pushing force. At the same time, a pulling force is generated between the fixed scroll and the swing scroll.

However, when the pulling force is too large, the thrust force between the turning scroll and the fixed scroll increases, and the sliding friction between the tip of each lap and the tooth root is increased, which lowers the efficiency of the compressor. Therefore, since it is necessary to adjust the pulling force to an appropriate magnitude, in the scroll compressor described in Patent Document 1, the back pressure chamber and the suction chamber communicate with each other via the back pressure regulating valve, and the fluid in the back pressure chamber is sucked in accordance with the pressure difference between the back pressure chamber and the suction chamber. It is relief by thread and adjusts the magnitude of back pressure.

However, according to the back pressure adjusting method described in Patent Document 1, since the fluid of the intermediate pressure obtained by compressing once is expanded and returned to the suction chamber, a compression loss occurs from the entire scroll compressor, and the efficiency of the compressor is deteriorated. There is.

Moreover, according to the back pressure adjustment method of patent document 1, although it adjusts automatically to back pressure = suction pressure + alpha (constant value), depending on the operating conditions of a compressor, the optimal back pressure value may greatly shift | deviate from suction pressure + alpha. As a result, when the back pressure is excessive, the sliding loss is increased. When the back pressure is excessive, the leakage is increased and the loss is increased. Therefore, there is a problem that the efficiency of the compressor is lowered in any way.

An object of this invention is to reduce the loss accompanying back pressure adjustment which adjusts the pulling force of a fixed scroll and a revolving scroll.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a plurality of compression chambers between a fixed scroll in which a spiral wrap is installed on a hard plate, and rotatably opposite to the fixed scroll, to form a plurality of compression chambers. It is introduced through a spiral scroll in which a spiral wrap is placed upright, a back pressure chamber provided at the rear of the swing scroll, and an intermediate pressure of discharge pressure and suction pressure is introduced, and a communication path formed at the end of the outermost wrap of the fixed scroll. A scroll compressor comprising a back pressure regulating valve for relieving a fluid in the back pressure chamber through the communication path to the suction chamber or the compression chamber at the beginning of compression in accordance with a difference between a suction pressure or a compression initial pressure and a pressure in the back pressure chamber. A through hole communicating the compression chamber and the back pressure chamber that is not in communication with the communication path is covered by the turning scroll. And that the feature.

Thus, since the through-hole which communicates a back pressure chamber and a compression chamber was provided in the revolving scroll, when the pressure of a back pressure chamber becomes excessive, the fluid in a back pressure chamber will flow out into a suction chamber or a compression chamber of a compression initial stage through a back pressure control valve and a communication path. At the same time, some flow out through the through hole into the compression chamber higher than the pressure of the suction chamber or the compression chamber at the beginning of compression. As a result, in order to adjust the back pressure, part of the pressure in the back pressure chamber obtained by compressing once is released to the compression chamber higher than the pressure in the suction chamber as compared with the expansion loss in the case of total relief of the total amount of the fluid in the suction chamber or the compression chamber at the initial stage of compression. The loss seen from the whole of the compressor can be reduced.

In this case, it is preferable that the through hole penetrates from the hard plate of the revolving scroll facing the back pressure chamber to the end of the wrap. Moreover, it can form in the hard board of the revolving scroll facing a back pressure chamber. In any case, it is preferable that the hole diameter of the through hole on the side communicating with the compression chamber is smaller than the hole diameter on the side communicating with the back pressure chamber.

In particular, in the case where the through-hole is penetrated from the hard disk of the swinging scroll to the tip of the wrap, the minute end of the lap slides with the flat plate of the fixed scroll, where the tip of the lap slides when the fluid in the back pressure chamber enters the compression chamber through the through-hole. Through a gap. Since this gap becomes a flow path resistance, free flow of fluid can be suppressed compared with the case where a back pressure chamber and a compression chamber directly communicate, and the pressure fluctuation in a back pressure chamber can be suppressed small. In addition, the direction of flow changes from the back pressure chamber to the compression chamber and from the back pressure chamber to the back pressure chamber each time the swing scroll is rotated, but the compression loss (so-called breathing loss) due to this can be reduced.

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of this invention is described with reference to drawings. Fig. 1 is a sectional view showing the whole of the scroll compressor of the present embodiment. FIG. 2 (a) is a plan view seen from the lap side of the swing scroll according to the feature of the present embodiment, and FIG. 1 (b) is a sectional view taken along the line B-B of FIG.

As shown in Fig. 1, the fixed scroll 7 includes a hard plate 7a formed in a disk shape, a wrap 7b provided in a spiral shape on the hard plate 7a, and an outer circumferential side of the hard plate 7a. It is comprised by the support part 7d formed in the cylinder shape so that it may be located and surround the wrap 7b. The surface of the hard plate 7a in which the wrap 7b is standing up is made of the root 7c. In addition, the fixed scroll 7 is fixed to the frame 17 by bolts or the like at the support 7d, and the frame 17 integrated with the fixed scroll 7 has a casing 9 by fixing means such as welding. It is fixed to).

On the other hand, the revolving scroll 8 is disposed opposite to the fixed scroll 7 and is rotatably provided in the frame 17. Swivel scroll 8 is a spiral wrap 8b which stands up from the root plate 8a of the disk shape and the tooth root 8c which is the surface of the hard board 8a similarly to the wrap 7b of the fixed scroll 7. And the boss part 8d provided in the center of the back surface of the hard board 8a.

The casing 9 is formed in a sealed structure by accommodating a scroll portion consisting of the fixed scroll 7 and the revolving scroll 8, the motor 16, and the lubricant oil therein. The shaft 10 provided with the rotor 16a of the motor 16 is rotatably attached to the frame 17 and coaxial with the axis of the fixed scroll 7. The crank 10a is provided in the front-end | tip part of the shaft 10, and the boss | hub part 8d of the revolving scroll 8 is rotatably attached to the crank 10a via the revolving bearing 11. The swinging scroll 8 is attached with the axis eccentric with respect to the axis of the fixed scroll 7 by a predetermined distance δ. Moreover, the lap 8b of the revolving scroll 8 is shifted and overlapped with the lap 7b of the fixed scroll 7 by a predetermined angle in the circumferential direction. The Oldham ring 12 is attached as a mechanism for relatively swinging the swinging scroll 8 while restraining the swinging scroll 8 from rotating relative to the fixed scroll 7. When the swing scroll 8 is pivoted in this state, a plurality of crescent-shaped compression chambers 13 are formed in which the volume is continuously reduced as the center portion moves between the wraps 7b and 8b. For example, in the case of an asymmetric wrap, as shown in Fig. 3, the swinging inner compression chamber 13a and the swinging outer compression chamber 13b are formed on the inner and outer sides of the swing scroll 8, respectively.

The suction port 14 is formed in the fixed scroll 7, which is drilled on the outer circumferential side of the plate 7a so as to communicate with the compression chamber 13 on the outermost circumferential side, and the suction chamber is formed. have. Further, the discharge port 15 is drilled in the center of the hard plate 7a of the fixed scroll 7 so as to communicate with the compression chamber 13 on the innermost circumferential side, and the discharge chamber is formed.

Here, the characteristic structure of this embodiment is demonstrated. As shown in Figs. 2A, 2B, and 1, a through hole 1 is provided in the wrap 8b of the swinging scroll 8 to communicate the back pressure chamber 18 and the compression chamber 13 with each other. have. That is, the through hole 1 penetrates from the hard plate 8a of the revolving scroll facing the back pressure chamber 18 to the upper end of the lap 8b as shown in Fig. 2B. The position on the wrap 8b of the through hole 1 is set to a position at which the pressure on the compression chamber 13 side of the through hole 1 is close to a suitable back pressure value. For example, as shown in Fig. 3, the pressure on the compression chamber 13 side of the through hole 1 is a value in the middle of the pressure between the swinging inner compression chamber 13a and the swinging outer compression chamber 13b. do. In addition, since the pressure in the turning inner compression chamber 13a and the turning outer compression chamber 13b fluctuates during the turning scroll 8 in one turn, the value in the middle of each average pressure in the turning turn is the through hole ( It becomes the pressure on the compression chamber 13 side of 1).

Moreover, as shown in FIG.2 (b), the through hole 1 has the hole diameter d1 of the side which communicates with the compression chamber 13 more than the hole diameter d2 of the side which communicates with the back pressure chamber 18. As shown in FIG. It is formed small. That is, the tooth width of the fixed scroll 7 and the tooth width of the sliding wrap 8b are restrained from being reduced by the through hole 1 as much as possible.

The operation of the scroll compressor of the present embodiment configured as described above will be described. First, when the shaft 10 is driven to rotate by the motor 16, this rotation is transmitted from the crank 10a of the shaft 10 to the swing scroll 8 via the swing bearing 11. As a result, the swinging scroll 8 pivots with a turning radius of a predetermined distance 6 about the axis of the fixed scroll 7. During this swing movement, the swing scroll 8 is constrained by the Oldham ring 12 so as not to rotate. And the compression chamber 13 which arises between each wrap 7b, 8b by the turning movement of the turning scroll 8 continuously moves to the center, and the volume of the compression chamber 13 continuously shrinks according to the movement. do. As a result, the fluid sucked from the suction port 14 is sequentially compressed in each compression chamber 13, and the compressed fluid is discharged from the discharge port 15. The discharged fluid is supplied from the discharge pipe 6 through the case 9 to, for example, a refrigeration cycle.

On the other hand, the lubricating oil is stored and held at the bottom of the case 9, and the pressure around it is discharge pressure. Since the pressure in the back pressure chamber 18 is lower than the discharge pressure, the lubricating oil stored and held at the bottom of the case 9 flows into the back pressure chamber 18 through the through hole 3 provided in the shaft 10. Specifically, part of the lubricating oil reaches the back pressure chamber 18 while lubricating the main bearing 5 via the lateral hole 4 provided in the shaft 10. Further, the other lubricating oil reaches the upper part of the crank 10a of the shaft 10 through the through hole 3, lubricates the swivel bearing 11 and enters the back pressure chamber 18. Here, when the lubricating oil passes through the main bearing 5 and the slewing bearing 11, since the bearing clearance is small, it is throttled and enters the back pressure chamber 18 at a pressure lower than the discharge pressure. When the back pressure rises, the lubricating oil entering the back pressure chamber 18 opens the back pressure regulating valve 2 provided in the communication path to the suction chamber and enters the suction chamber. Then, it is discharged from the discharge port 15 through the compression chamber 13, part is discharged from the discharge pipe 6 in the refrigeration cycle, the remainder is separated from the refrigerant in the case 9 and stored in the bottom.

4 and 5, the configuration and operation of the back pressure regulating valve 2 will be described. The back pressure regulating valve 2 is a suction chamber (or a space 2d communicating with the back pressure chamber 18 and a communication path 2f provided at this end of the outermost wrap 7e of the fixed scroll 7). The valve main body 2a is arrange | positioned so that the space 2e which communicates with the compression chamber 13 of an initial stage of compression may be divided. The valve main body 2a is pressed by the opening part which communicates with the space 2d by the spring 2b. The valve body 2a has a pressure corresponding to the pressure of the suction chamber in the space 2e where the pressure in the space 2d is introduced via the communication path 2f or the compression chamber at the initial stage of compression, and the pressure corresponding to the pressing force of the spring 2b. When it becomes higher than the sum, it moves upward and makes the space 2d and the space 2e communicate. As a result, the pressure (back pressure) Pb of the back pressure chamber is referred to as the pressure (suction pressure) of the suction chamber or the pressure of the compression chamber at the initial stage of compression as Ps, and the pressure corresponding to the pressing force of the spring 2b is α (constant value). ), It is controlled as in Equation 1 below.

(Wed 1)

Pb = Ps + α

Next, the effect | action of the characteristic structure of this embodiment is demonstrated. First, when the back pressure is increased by the lubricating oil constantly flowing into the back pressure chamber 18 and the refrigerant dissolved therein, part of the fluid in the back pressure chamber 18 flows into the compression chamber 13 through the through hole 1. . At the same time, the fluid in the back pressure chamber 18 flows into the suction chamber or the compression chamber 13 in the initial compressed state where the pressure is slightly higher than the suction pressure through the back pressure regulating valve 2. Here, when the back pressure rises and the back pressure regulating valve 2 is opened, since the fluid once compressed re-expands to the suction pressure or the pressure in the compression chamber close thereto, compression loss occurs. In this regard, in this embodiment, not all of the fluid in the back pressure chamber 18 re-expands to the suction pressure or the pressure in the compression chamber close thereto through the back pressure regulating valve 2, and part of the fluid is in the through hole 1. By entering the compression chamber 13 which has risen to a pressure close to the back pressure through, the re-expansion loss can be reduced, and a scroll compressor having a high compression efficiency can be realized. In addition, since only the through hole 1 is provided in the revolving scroll 8, a significant increase in cost does not occur.

In addition, in this embodiment, since the through-hole 1 is provided in the wrap 8b of the turning scroll 8, when the fluid in the back pressure chamber 18 enters the compression chamber 13 through the through-hole 1, A small gap between the tip of the wrap 8b of the swing scroll 8 and the tooth root 7c of the fixed scroll 7 is passed. Since this gap becomes a flow path resistance and can freely flow in and out of fluid compared with the case where the back pressure chamber 18 and the compression chamber 13 directly communicate, the pressure fluctuations in the back pressure chamber 18 can be suppressed small. In addition, the direction of flow changes from the back pressure chamber 18 to the compression chamber 13 and from the compression chamber 13 to the back pressure chamber 18 every time the swing scroll 8 is rotated one by one. So-called respiratory loss) can be suppressed small.

6, the operation of the back pressure adjustment of the present invention will be described. 6 is a graph schematically showing the relationship between the back pressure Pb and the suction pressure Ps, the horizontal axis represents the suction pressure Ps, and the vertical axis represents the back pressure Pb. In the operating conditions with the compressor, the sliding loss is increased when the back pressure Pb is excessive, and the leakage is increased when the back pressure Pb is excessive, so that an optimum back pressure value exists. The optimum back pressure value takes different values depending on the various operating conditions of the compressor. Points 19a to 19d in the drawing schematically plot the optimum back pressure value for representative operating conditions of the compressor.

Now, when back pressure is adjusted using the back pressure regulating valve 2 which communicates a back pressure chamber and a suction chamber, it becomes Pb = Ps + alpha, as shown in said Formula 1, and is represented by the line C-E-D in a figure. In addition, when the back pressure regulating valve 2 is communicated with the compression chamber in the initial compressed state where the pressure slightly higher than the suction pressure, Pb = k · Ps + α, which is not shown, is a straight line that moves upward from the line CED. Is displayed. Where k is the compression coefficient of the initial compression state.

Here, in the case where the back pressure is adjusted by the back pressure regulating valve 2 which communicates the back pressure chamber and the suction chamber, the points 19a and 19b almost coincide with the optimum back pressure values. At the point 19d, the back pressure Pb is larger than the optimum value. On the other hand, when back pressure is adjusted by the through-hole 1 provided in the turning scroll 8, since back pressure Pb becomes the average pressure of the compression chamber 13 which communicates with the through-hole 1, suction pressure Ps Is multiplied by a constant compression coefficient β corresponding to the average pressure of the compression chamber 13, and can be expressed by the following expression (2).

(Wed 2)

Pb = Ps × β

Back pressure Pb at this time is represented by the straight line of the line A-E-B in a figure. This line A-E-B is almost identical at the points 19b, 19c, and 19d of the optimum back pressure value, but becomes larger than the optimum value at the point 19a.

On the contrary, according to this embodiment, since back pressure is adjusted in both the back pressure regulating valve 2 and the through-hole 1 provided in the turning scroll 8, when back pressure Pb becomes high, a back pressure chamber The fluid in 18 is intended to flow much into the space of the lower pressure. That is, the back pressure adjustment by the through-hole 1 shown by the dotted line becomes dominant in the operating condition which becomes the suction pressure lower than the suction pressure in the point E, ie, the area on the left side than the point E. In addition, the back pressure adjustment by the back pressure regulating valve 2 becomes dominant in the operating condition that the suction pressure becomes higher than the suction pressure at the point E, that is, the region on the right side from the point E. In other words, the characteristic of FIG. 6 is that the suction pressure of the back pressure regulating valve 2 and the operating straight line CED of the back pressure, the suction pressure of the through hole 1 and the operating straight line AEB of the back pressure intersect on the way, and also the back pressure. It is a characteristic that the gradient of the operating straight line of the adjustment valve 2 is formed smaller than the gradient of the operating straight line of the through hole 1.

Therefore, when back pressure is adjusted by both the back pressure regulating valve 2 and the through-hole 1 provided in the turning scroll 8, it operates according to the line A-E-D in a figure. At this time, by adjusting the constant of the spring 2b of the back pressure regulating valve 2 and the position of the through hole 1, it is possible to almost match the optimum back pressure value under typical operating conditions up to the points 19a to 19d. . That is, the degree of freedom of back pressure adjustment increases, and a scroll compressor with high compression efficiency can be realized in a wider operating range.

Incidentally, in the region on the right side of the point E in FIG. 6, the average pressure in the compression chamber 13 through which the through hole 1 is passed is higher than the pressure in the back pressure chamber 18. Therefore, in the through hole 1, the flow from the compression chamber 13 to the back pressure chamber 18 becomes the mainstream, and the effect of reducing the re-expansion loss is small. However, the lubricating oil stored in the bottom of the case 9 which is an atmosphere of discharge pressure and the refrigerant melted in the lubricating oil flows into the back pressure chamber 18 by the portion of the fluid flowing back from the compression chamber 13 into the back pressure chamber 18. Since the amount is reduced, the compression efficiency does not decrease.

As explained above, according to this embodiment, the loss by the re-expansion of the compressed fluid accompanying back pressure adjustment which adjusts the pulling force of a fixed scroll and a revolving scroll can be reduced. In particular, it is possible to realize a scroll compressor having a high compression efficiency in a wide operating range.

In the above embodiment, an example in which the through hole 1 is drilled in the wrap of the swinging scroll has been described. However, the present invention is not limited thereto, and the through hole may be provided so as to communicate the compression chamber and the back pressure chamber. For example, a through hole may be provided in the portion of the hard plate of the revolving scroll to communicate the back pressure chamber with the compression chamber. In this case, it is preferable to make the hole diameter of the through hole as small as possible to give the flow path resistance.

According to this invention, the loss accompanying back pressure adjustment which adjusts the pulling force of a fixed scroll and a revolving scroll can be reduced.

Claims (6)

A fixed scroll having a spiral wrap erected on the hard board, and a spiral wrap provided on the hard board so as to be pivotable to face the fixed scroll, and which form a plurality of compression chambers between the fixed scroll wrap Suction pressure or compression initial pressure and the back pressure introduced through a swing scroll, a back pressure chamber provided on a rear surface of the swing scroll and introducing an intermediate pressure between a discharge pressure and a suction pressure, and a communication path provided in an outermost wrap of the fixed scroll. A scroll compressor having a back pressure regulating valve for relieving a fluid in the back pressure chamber through the communication path to the suction chamber or the compression chamber in accordance with a difference between the pressure of the chamber, the compression chamber and the back pressure not communicating with the communication path. A scroll compressor comprising a through hole communicating with a thread in the pivoting scroll. The scroll compressor according to claim 1, wherein the through hole penetrates from the hard plate of the swinging scroll facing the back pressure chamber to the end of the wrap. The scroll compressor according to claim 1, wherein the through hole is provided in a hard plate of the swinging scroll facing the back pressure chamber. The scroll compressor according to claim 2, wherein the through hole has a smaller hole diameter on the side communicating with the compression chamber than a hole diameter on the side communicating with the back pressure chamber. The scroll compressor of claim 1, wherein the fluid is a refrigerant gas. The suction pressure of the through-holes and the back pressure of the back pressure are controlled by the back pressure adjusted by the back pressure adjustment valve with respect to the suction pressure of the suction pressure and the back pressure of the back pressure adjusting valve. And a change in the back pressure adjusted by the through hole relative to the scroll compressor.

Images