GB2325705A

GB2325705A - Scroll compressor

Info

Publication number: GB2325705A
Application number: GB9815484A
Authority: GB
Inventors: Shuji Motegi; Fumiaki Sano; Ikeda Kiyoharu; Eiji Watanabe; Toshiyuki Nakamura; Masayuki Kakuda; Yoshihide Ogawa; Shinji Nakashima
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1995-03-22
Filing date: 1995-09-29
Publication date: 1998-12-02
Anticipated expiration: 2015-09-29
Also published as: GB9815484D0; GB2325705B

Abstract

A fixed scroll 2 is provided with a plate-like spiral tooth 6 on a base plate (4, Fig 1) having at its centre a discharge port 5 for high-pressure gas. A spiral tooth 15 on the base plate 13 of an orbiting scroll 12 engages the spiral tooth 6 to form a compression space periodically consisting of a low pressure chamber 30, an intermediate pressure chamber 29, and a high pressure chamber 28. At least one of the base plates (4), 13 has a counterboring or recess 36,37 adjacent the inner end portion of the spiral tooth 6,15. During the motion of the orbiting scroll 12 the counterboring 36,37 communicates with the intermediate pressure chamber 29 after the high pressure chamber 28 and the intermediate pressure chamber 29 communicate with each other via the side surfaces of the spiral teeth 6,15.

Description

SCROLL COMPRESSOR This invention relates to a scroll compressor provided with an orbiting scroll and a fixed scroll for use as a compressor of a refrigerator, an air conditioner, etc.

Figure 4 is a longitudinal sectional view of a conventional scroll compressor, for example, disclosed in Japanese Patent Laid-Open No.Sho 62-265487, wherein numeral 1 is a sealed vessel and numeral 2 is a fixed scroll provided with a base plate 4 fixed to an upper frame 3 having an outer peripheral surface secured to one end face in the sealed vessel 1, a discharge port 5 disposed at the center of the base plate 4, and a plate-like spiral tooth 6 disposed on the side of the upper frame 3 of the base plate 4.

Numeral 7 is a partition plate secured in the sealed vessel 1, placed on the side of the base plate 2 of the fixed scroll 2 opposed to the upper frame 3, and provided with a discharge port 8 at the center. Numeral 9 is a discharge 10 valve having a valve guardlmounted on the side of the partition plate 7 opposed to the fixed scroll 2 with a bolt 11. Numeral 12 is an orbiting scroll disposed between the fixed scroll 2 and the upper frame 3 and having a base plate 13 provided with a plate-like spiral tooth 15 engaging the plate-like spiral tooth 6 of the fixed scroll 2 for forming a compression space 14.

Numeral 16 is an orbiting saft disposed on the side of the base plate 13 of the orbit scroll 12 opposed to the fixed scroll 2. Numeral 17 is a trust face which is formed on the side of the orbiting shaft ': of the base plate 13 of the orbiting scroll 12 and comes in plane contact with a thrust bearing 18 of the upper frame 3 for sliding. Numeral 19 is an Oldham's ring having an upper claw engaged slidably in a linear direction in a pair of Oldham's guide grooves formed on the outer peripheral surface of the base plate 13 of the orbiting scroll 12.

The upper frame 3 is also formed with Oldham's guide grooves having a phase difference of about 90with the Oldham's guide grooves of the orbiting scroll12, in which a lower claw of the Oldham's ring 19 is engaged slidably in a linear direction.

Numeral 20 is a lower frame which has an outer peripheral surface secured in the sealed vessel 1, is placed on the side of the upper frame 3 opposed to the orbiting scroll 12, and is provided with a main bearing radially supporting a main shaft 22 driven by an electric motor 21 at the center.

Numeral 24 is an orbiting bearing which is disposed at an end of the orbiting scroll 12 side of the main shaft 22 and is formed like a circular cylinder eccentric in the same direction as the eccentric direction of the orbiting scroll 12 for pivotally supporting the orbiting shaft 16 of the base plate 13 of the orbiting scroll 12.

Numeral 25 is a suction pipe for guiding a lowpressure refrigerant gas before compressed to the inside of the sealed vessel 1 and numeral 25 is a discharge pipe for discharging a high-pressure refrigerant gas after compressed to the outside of the sealed vessel 1.

Numeral 27 is a high pressure space formed between the end face of the sealed vessel 1 and the partition plate 7. Numerals 28 to 30 are a compression space 14 formed like a pair of crescents with the plate-like spiral tooth 6 of the fixed scroll 2 meshing with the plate-like spiral tooth 15 of the orbiting scroll 12; numeral 28 is a high pressure chamber numeral 29 is an intermediate pressure chamber, and a numeral 30 is a low pressure chamber. Numeral 31 is a compression high pressure section formed by the high pressure chamber 28, the discharge port S of the fixed scroll 2, and the discharge port 8 of the partition plate 7.

The conventional scroll compressor has the structure.

When the electric motor 21 is energized, the orbiting scroll 12 is driven via the main shaft 22 and the orbiting shaft 16.

At this time, rotation of the orbiting scroll 12 with respect to the upper frame 3, namely, the fixed scroll 2 is restrained by the Oldham's ring 19. Thus, the orbiting scroll 12 makes the orbiting motion with respect to the fixed scroll 2.

A refrigerant gas sucked through the suction pipe 25 is taken in the low pressure chamber 30 of the compression space 14 formed like a pair of crescents wit the plate-like spiral tooth 6 of the fixed scroll 2 meshing with the plate like spiral tooth 15 of the orbiting scroll 12.

The compression space 14 decreases in volume in order from the low pressure chamber 30 to the intermediate pressure chamber 29 to the high pressure chamber 28, whereby the refrigerant gas is compressed.

Next, the compressed high-pressure refrigerant gas passes through the discharge port 5 of the fixed scroll 2 and the discharge port 8 of the partition plate 7, pushes and opens the discharge valve 9, is discharged into the high pressure space 27, and is sent outside the sealed vessel 1.

Just after the scroll compressor stops, the discharge valve 9 is closed, preventing the refrigerant gas in the high pressure space 27 from passing through the compression high pressure section 31 and flowing reversely to the refrigerant gas flow at the normal motion time, thereby blocking the reverse orbiting operation of the orbiting scroll 12 to the normal motion time.

The discharge valve 9 opens for discharging highpressure refrigerant gas almost throughout the time from starting to stopping of the scroll compressor operation. The operating scroll compressor has a characteristic wherein the high pressure chamber 28 and the intermediate pressure chamber 29 formed by the plate-like spiral tooth 6 of the fixed scroll 2 and the plat-like spiral tooth 15 of the orbiting scroll 12 are comnunicated with each other at 2 predetermined timing.

Just after the high pressure chamber 28 and the intermediate pressure chamber 29 are communicated with each other, the-pressure in the compression high pressure section 31 becomes lower than the pressure in the high pressure space 27, closing the discharge valve 9. An impulse wave is produced in the compression high pressure section 31 by water hammering of the refrigerant gas in the vicinity of the discharge valve 9 when the discharge valve 9 is closed. A pressure ripple in the discharge port 5 of the fixed scroll 2 caused by the impulse wave becomes a vibration source, increasing noise of the scroll compressor.

Figures 5, 6A, and 6B show another conventional scroll compressor, for example, disclosed in Japanese Patent Laid-Open No.Sho 62-75089. Figure 5 is a longitudinal sectional view of the main part of the conventional scroll compressor and each of Figures 6A and 6B is a plan view explaining the operation of the scroll compressor in Figure 5. Parts not shown in Figure 5 6A,or 6B are the same as those of the scroll compressor in Figure 4. Parts identical with or similar to those previously described with reference to Figure 4 are denoted by the same reference numerals in Figures 5 6A,and ó B. Numeral 32 is an orbiting bearing disposed on the side of a base plate 13 of an orbiting scroll 12 opposed to a fixed scroll 2, in which an orbiting shaft 16 of the base plate 13 of the orbiting scroll 12 is fitted rotatably.

Numeral 33 is a thrust member which is disposed on a surface facing the base plate 13 of the orbiting scroll 12 of an upper frame 3 and comes in plane contact with the base plate 13 for sliding. Numeral 34 is an Oldham's guide groove formed in the upper frame 3 and placed forming a phase difference of about 90 with an Oldham's guide groove of the orbiting scroll 12, in which a lower claw 35 of an Oldham's ring 19 is engaged slidably in a linear direction.

Numeral 36 is a counterboring disposed in a base plate 4 of the fixed scroll 2, comprising a cutaway part (recess) corresponding to the center of a plate-like spiral tooth 6.

Numeral 37 is a counterboring . disposed in the base plate 13 of the orbiting scroll 12, comprising a cutaway part (recers) corresponding to the center of a plate-like spiral tooth 15.

The conventional scroll compressor has the structure.

When an electric motor 21 is energized, the orbiting scroll 12 is driven via a main shaft 22 and the orbiting shaft 16.

At this time, rotation of the orbiting scroll 12 with respect to the upper frame 3, namely, the fixed scroll 2 is restrained by the Oldham's ring 19. Thus, the orbiting scroll 12 make the orbiting motion with respect to the fixed scroll 2.

A refrigerant gas sucked through a suction pipe 25 is taken in a low pressure chamber 30 of a compression space 14 formed like a pair of crescents with the plate-like spiral tooth 6 of the fixed scroll 2 meshing with the plate-like spiral tooth 15 of the orbiting scroll 12.

The compression space 14 decreases in volume in order from the low pressure chamber 30 to-an intermediate pressure chamber 29 to a high pressure chamber 28, whereby the refrigerant gas is compressed.

Next, the compressed high-pressure refrigerant gas is discharged through the counterboring 36 of the fixed scroll 2, the counterboring 37 of the orbiting scroll 12, and a discharge port 5 of the fixed scroll 2. As shown in Figs.GA,6B, the counterboring 36 of the fixed scroll 2 and the counterboring 37 of the orbiting scroll 12 defining a flow passage of high-pressure refrigerant gas at a predetermined timing are communicated with the intermediate pressure chamber 29.

Therefore, the counterboring 36 of the fixed scroll 2 and the counterboring 37 of the orbiting scroll 12 provide a discharge flow passage when the refrigerant gas is discharged, decreasing a discharge pressure loss, thereby decreasing scroll compressor input caused by the discharge pressure loss. However, when the counterborings 35 and 37 are communicated with the intermediate pressure chamber 29, the high-pressure refrigerant gas is returned to the intermediate pressure chamber 29, then again discharged through the discharge port 5 of the fixed scroll 2 by the compression operation of the compression space 14.

In the conventional scroll compressor as described above, if the discharge valve 9 is omitted, the orbiting scroll 12 performs the reverse orbiting operation to the normal motion time just after the scroll compressor stops.

Since it is feared at the time that reverse rotation noise may be produced or that the orbiting bearing 32, etc., may be damaged depending on the situation, the discharge valve 9 is provided.

However, if the discharge valve 9 is closed during the operation of the scroll compressor, an impulse wave is produced in the discharge port 5 of the fixed scroll 2 by water hammering of the refrigerant gas in the vicinity of the discharge valve 9. Noise occurs with the impulse wave as a vibration source, causing noise of the scroll compressor to increase.

The counterboring 36 of the fixed scroll 2 and the counterboring 37 of the orbiting scroll 12 defining a flow passage of high-pressure refrigerant gas at a predetermined timing during the operation of the scroll compressor are communicated with the intermediate pressure chamber 29. Since the pressure in the intermediate pressure chamber 29 of the compression space 14 instantly increases just after they are communicated, the fixed scroll 2 and the orbiting scroll 9 are vibrated, increasing noise of the scrol' compressor.

It would be desirable to be able to provide scroll compressor which has fixed and orbiting scrolls provided with counterborings and is low in noise caused by pressure fluctuation in an intermediate pressure chamber when the counterborings are communicated with the intertediate pressure chamber.

According to the invention, there is provided a scroll compressor comprising a fixed scroll disposed in a sealed vessel and provided with a plate-like spiral tooth on a base plate having a discharge port for a high-pressure refrigerant gas at a center, an orbiting scroll disposed in the sealed vessel and having a base plate provided with a plate-like spiral tooth engaging the plate-like spiral tooth of the fixed scroll for forming a compression space consisting of a high pressure chamber, an intermediate pressure chamber, and a low pressure chamber, and a counterboring made in at least either of the base plates of the fixed and orbiting scrolls, having a cutaway part corresponding to a center of the plate-like spiral tooth of the base plate, and set to a form and position such that when the fixed and orbiting scrolls operate, the counterboring communicates with the intermediate pressure chamber at a later timing than the high pressure chamber and the intermediate pressure chamber communicate with each other on side faces of the plate-like spiral teeth of the fixed and orbiting scrolls.

The scroll compressor comprises a counterboring made in at least either of the base plates of the fixed and orbiting scrolls, having a cutaway part corresponding to a center of the plate- ike spiral tooth of the base plate, and set to a form and position such that when the fixed and orbiting scrolls operate, the counterboring communicates with the intermediate pressure chamber at the same timing as the discharge port of the fixed scroll communicates with the intermediate pressure chamber.

According to the invention, there is provided a scroll compressor comprising a fixed scroll disposed in a sealed vessel and provided with a plate-like spiral tooth on a base plate having a discharge port for a high-pressure refrigerant gas at a center, an orbiting scroll disposed in the sealed vessel and having a base plate provided with a plate-like spiral tooth engaging the plate-like spiral tooth of the fixed scroll for forming a compression space consisting of a high pressure chamber, an intermediate pressure chamber, and a low pressure chamber, and a counterboring made in at least either of the base plates of the fixed and orbiting scrolls and having a cutaway part corresponding to a center of the plate-like spiral tooth of the base plate and 2 part formed along an .:volute curve.

The counterboring is made in at least either of the base plates of the fixed and orbiting scrolls, has a cutaway part corresponding to the center of the plate-like spiral tooth of the base plate, and is set to a form and position such that it communicates with the intermediate pressure chamber at a later timing than the high pressure chamber and the intermediate pressure chamber communicate with each other on side faces of the plate-like spiral teeth of the fixed and orbiting scrolls. Thus, the scroll compressor has the structure wherein the counterboring is made in at least either of the base plates of the fixed and orbiting scrolls, decreasing rapid and large pressure change in the compression space when the counterboring communicates with the intermediate pressure chamber.

The counterboring is made in at least either of the base plates of the fixed and orbiting scrolls, has a cutaway part corresponding to the center of the plate-like spiral tooth of the base plate, and is set to a form and position such that it communicates with the inte=ediate pressure chamber at the same timing as the discharge port of the fixed scroll communicaees with the intermediate pressure chamber. Thus, pressure change in the intermediate pressure chamber when the counterboring communicates with the intermediate pressure chamber occurs once per revolution.

The counterboring is made in at least either of the base plates of the fixed and orbiting scrolls and has a cutaway part corresponding to the center of the plate-like spiral tooth of the base plate and a part formed along an involute curve, whereby just after either of the counterborings of the fixed and orbiting scrolls communicates with the intermediate pressure chamber, a communication area is formed in a wide range along the outer side faces of the opposed plate-like spiral teeth. Thus, a sufficient flow passage area of a high-pressure refrigerant gas is provided, decreasing a pressure loss of the highpressure refrigerant gas.

At least either of the fixed and orbiting scrolls formed with the counterboring is provided with a platelike spiral tooth having a notch at the a tip center of the center, whereby the high-pressure refrigerant gas flow passage is enlarged to the area resulting from adding the notch to the counterboring, furthermore decreasing the pressure loss of the high-pressure refrigerant gas.

In the accompanying drawings.

Figure 1 is a longitudinal sectional view showing the main part of at embodiment of the invention; ac of Figure 2A and 2B is an enlarged perspective view of b respective counterboring part in Figure 13; Each of Figures 3A to 3D is a plan view explaining the operatics of scroll compressor in Figure 1 Figure 4 is a longitudinal sectional view of a conventional scroll compressor; Figure 5 is a longitudinal sectional view of the main part of another conventional scroll compressor; and Each of Figures 6A and 6B is a plan view explaining the operation of scroll compressor in Figure 5.

Figure 1 is a longitudinal sectional view of the main part of a scroll compressor according to the preferred embodiment. Each of Figures 2A and 2B is an enlarged perspective view of a respective counterboring in Figure 1 . Each of Figure 3A to 3D is a plan view explaining the operation of the scroll compressor in Figure 1 . Parts identical with or similar to those previously described with reference to Figures 4 to 6B are denoted by the same reference numerals in Figures 1 - 3D. Numeral 36 is a counterboring disposed in a base plate 4 of a fixed scroll 2, ccPrising a cutaway part corresponding to the center of a plate-like spiral tooth 6.

Numeral 37 is a counterboring disposed in 2 base plate 13 of an orbiting scroll 12,comprising a cutaway part corresponding to the center of a plate-like spiral tooth 15.

Numeral S1 is a notch made at the tip center of the center of the plate-like spiral tooth 15 of the orbiting scroll 12.

Numeral 52 is a counterboring communication part communicated with the counterboring 36 of the fixed scroll 2 and an intermediate pressure chamber 29 and numeral 53 is a counterboring communication part communicated with the counterboring 37 of the orbiting scroll 12 and the intermediate pressure chamber 29.

Numeral 54 is an outer side face of the center of the plate-like spiral tooth 6 of the fixed scroll 2, numeral 55 is an outer side face of the center of the plate-like spiral tooth 15 of the orbiting scroll 12, numeral 56 is a side face communication part between the plate-like spiral teeth 6 and 15.

In the scroll compressor having the structure, when an electric motor is energized, the orbiting scroll 12 is driven via a main shaft 22, a slider 44 revolved by the main shaft 22, and an orbiting bearing 16. At this time, rotation of the orbiting scroll 12 with respect to a frame 3, namely, the fixed scroll 2 is restrained by an Oldham's ring 19.

Thus, the orbiting scroll 12 makes the orbiting motion with respect to the fixed scroll 2.

A low essure re refrigerant gas sucked through n suction pipe 25 is taken ~-. a low pressure chamber 30 of a compression space 14 forme like a pair cf crescents Fth the plate-like spiral tooth 6 =f the fixed scroll 2 meshing with the plate-like spiral toot 15 of the orbiting scroll 2.

The compression space 14 decreases in volume n order from the low pressure carver 30 to the intermediate pressure chamber 29 to a high pressure chamber 28, whereby the refrigerant gas is compressed.

Next, the compressed high-pressure refrigerant gas passes through the notch 5i of the plate-like spiral tooth 15 of the orbiting scroll 12, the counterboring 36 o the fixed scroll 2, the counterboring 37 of the orbiting scroll 12, and the discharge port 5 of the fixed scroll 2, and is discharged into a high pressure space 27 and sent outside a sealed vessel 1 through a discharge pipe 26.

The plane of a pin part 43 of the main shaft 22 and the plane of the inner face of the slider 44 make linear slide motion in the eccentric direction of the orbiting scroll 12.

Thus, a predetermined force such as a centrifugal force acts on the orbiting scroll 12 in the eccentric direction, whereby the orbiting scroll 12 is pressed in the radial direction of the fixed scroll 2, thereby preventing a gap from occurring between the side face of the plate-like spiral tooth 15 of the orbiting scroll 12 and the side face of the plate-like spiral tooth 6 of the fixed scroll 2.

The forms and positions of the counterboring 36 of the fixed scroll 2 and the counterboring 37 of the orbiting scroll 12 are set as shown in Figures 3A to 3D so that the counterboring 36 of the fixed scroll 2 and the counterboring 37 of the orbiting scroll 12 are communicated with the intermediate pressure chamber 29 at the counterboring communication parts 52 and 53 respectively at almost the same timing as the discharge port 5 of the fixed scroll 2 is communicated with the intermediate pressure chamber 29 after the high pressure chamber 28 and the intermediate pressure chamber 29 are communicated with each other at the side face communication part 56 between the plate-like spiral teeth.

Therefore, after the high pressure chamber 28 and the intermediate pressure chamber 29 are gently communicated with each other at the side face communication part 56 between the plate-like spiral teeth and the pressure difference between the high pressure chamber 28 and the intermediate pressure chamber 29 decreases, the counterboring 36 of the fixed scroll 2 and the counterboring 37 of the orbiting scroll 12 are communicated with the intermediate pressure chamber 29. Thus, rapid and large pressure fluctuation in the intermediate pressure chamber 29 just after the communication decreases, so that noise of the scroll compressor with the pressure fluctuation with a vibration source lessens.

Normally, the pressure fluctuation of the intermediate chamber 29 is twice per one revolution since the discharge port 29 of the fixed scroll 2 and the intermediate pressure chamber 29 are communicated with each other after the intermediate chamber 29 is communicated with the counterboring communication parts 52 and 53 of the base plate 4 and 13 of the fixed scroll 2 and the orbiting scroll 12.

However, the forms and positions of the counterboring 36 and 37 are set so that the counterboring communication parts 52 and 53 of the base plates 4 and 13 of the fixed scroll 2 and the orbiting scroll 12 are communicated with the intermediate pressure chamber 29 at almost the same timing as the discharge port S of the fixed scroll 2 is communicated with the intermediate pressure chamber 29. Thus, when the discharge port 5 of the fixed scroll 2, the counterboring 36 of the fixed scroll 2, and the counterboring 37 of the orbiting scroll 12 are communicated with the intermediate pressure chamber 29, pressure fluctuation in the intermediate pressure chamber 29 occurs once per revolution, so that noise of the scroll compressor caused by the pressure fluctuation decreases.

The form of the counterboring 36 of the fixed scroll 2 is almost the same as an involute curve of the outer side face 55 of the plate-like spiral tooth 15 of the orbiting scroll i2 when it is communicated it the inter:ediate pressure chamber 25. Thus, just after the communication, the conterboring communication part 52 of time fixed scroll 2 is foiled in a wide range along the outer side face 5 of the plate-like spiral tooth 15 of te orbiting scroll 12.

The form of the counterboring 37 of the orbiting scrol' 12 is almost the same as an involute curve of the outer side face 54 of the plate-like spiral tooth 6 of the fixed scroll 2 when it is communicated with the intermediate pressure chamber 29. Thus, just after the co=unication, the counterboring communication part 53 of the orbiting scroll 12 is formed in a wide range along the outer side face 54 of the plate-like spiral tooth 6 of the fixed scroll 2.

Thus, the counterboring 36 of the fixed scroll 2 and the counterboring 37 of the orbiting scroll 12 are communicated with the intermediate pressure chamber 29 in a sufficient communication area to such a degree that a refrigerant gas pressure loss does not occur. Therefore, a sufficient flow passage area of high-pressure refrigerant gas can be provided, decreasing the pressure loss, thereby improving performance of the compression scroll.

The notch 51 made at the tip center of the center of the plate-like spiral tooth 6, 15 of at least either of the fixed scroll 2 and the orbiting scroll 12 provides a larger flow passage area of high-pressure refrigerant gas than the case where only the counterborings 3i and 37 are provided. Therefore, the pressure Loss of the high-pressure refrigerant gas can be furthermore decreased, improving performance of the scroll compressor all the cure.

Accordingly, there is provided a scroll compressor comprising a fixed scroll disposed in a sealed vessel and provided with a plate-like spiral tooth on a base plate having a discharge port for a high-pressure refrigerant gas at the center, an orbiting scroll disposed in the sealed vessel and having a base plate provided with a plate-like spiral tooth engaging the plate-like spiral tooth of the fixed scroll for forming a compression space consisting of a high pressure chamber, an intermediate pressure chamber, and a low pressure chamber, and a counterboring made in at least either of the base plates of the fixed and orbiting scrolls, having a cutaway part corresponding to the center of the plate-like spiral tooth of the base plate, and set to a form and position such that when the fixed and orbiting scrolls operate, the counterboring communicates with the intermediate pressure chamber at a later timing than the high pressure chamber and the intermediate pressure chamber communicate with each other on side faces of the plate-like spiral teeth of the fixed and orbiting scrolls.

Thus, the counterboring made in at least either of the base plates of the fixed and orbiting scrolls and having a cutaway part corresponding to the center of the plate-like spiral tooth of the base plate communicates with the intermediate pressure chamber at a later timing than the high pressure chamber and the intermediate pressure chamber communicate with each other on side faces of the plate-like spiral teeth of the fixed and orbiting scrolls. Thus, the scroll compressor has the structure wherein the counterboring is made in at least either of the base plates of the fixed and orbiting scrolls, decreasing rapid and large pressure change in the compression space when the counterboring communicates with the intermediate pressure chamber. Therefore, noise with the pressure ripple as a vibration source can be lessened for quieting the operation of the scroll compressor.

The scroll compressor comprises a counterboring made in at least either of the base plates of the fixed and orbiting scrolls, having a cutaway part corresponding to the center of the plate-like spiral tooth of the base plate, an set to a form and position such tat when the fixed and orbiting scrclls operate, the counterboring communicates with the intermediate pressure chamber at the same -timing as the discharge port of the fixed scroll communicates with the inter=ediate pressure chamber.

Thus, the couterboring made in at least either of the base plates of the fixed and orbiting scrolls and having a cutaway part corresponding of the fixed scroll for forming 2 compression space consisting of a high pressure chamber, an intermediate pressure chamber, and a low pressure chamber, and a counterboring made in at least either of the base plates of the fixed and orbiting scrolls and having a cutaway part corresponding to the center of the plate-like spiral tooth of the base plate and a part formed along an involute curve.

Thus, the counterboring is made in at least either of the base plates of the fixed and orbiting scrolls and has a cutaway part corresponding to the center of the plate-like spiral tooth of the base plate and a part formed along an involute curve, whereby just after either of the counterborings of the fixed and orbiting scrolls communicates with the intermediate pressure chamber, a communication area is formed in a wide range along the outer side faces of the opposed plate-like spiral teeth. Thus, a sufficient flow passage area of a high-pressure refrigerant gas is provided, decreasing a pressure loss of the highpressure refrigerant gas, improving performance of the scroll compressor.

At least either of the fixed and orbiting scrolls formed with the counterboring is provided with a platelike spiral tooth having a notch at the tip center of the center.

Thus, the high-pressure refrigerant gas flow passage is enlarged to the area resulting from adding the notch made at the tip center of the center of the plate-like spiral tooth to the counterboring of at least either of the fixed and orbiting scrolls. Thus, furthermore the pressure loss of the high-pressure refrigerant gas is decreased, improving performance of the scroll compressor.

Claims

Do ument =: 285973

Claims 1. A scroll compressor comprising, in a sealed vessel: a fixed scroll provided with a plate-like spiral tooth on a base plate having at its center a discharge port for high-pressure gas; an orbiting scroll having a base plate provided with a plate-like spiral tooth engaging the spiral tooth of the fixed scroll for forming a compression space periodically consisting of a high pressure chamber, an intermediate pressure chamber, and a low pressure chamber during motion of the orbiting scroll; and a counterboring in at least one of the base plates, the counterboring comprising a recess adjacent the inner end portion of the spiral tool of the said base plate, the counterboring having such a form and position that1 during the motion of the orbiting scroll, the counterboring communicates with the intermediate pressure chamber at a later timing than the high pressure chamber and the intermediate pressure chamber communicate with each other via the side surfaces of the spiral teeth.
2. A scroll compressor as claimed in daim 1, wherein the counterboring communicates with the intermediate pressure chamber at the same timing as the discharge port communicates with the intermediate pressure chamber.
3. A scroll compressor as claimed in daim 1 or 2, wherein a portion of the periphery of the counterboring has the shape d an involute curve.
4. A scroll compressor as claimed in any preceding daim, wherein a notch is formed in the radially inner surface of the inner end portion of at least one of the spiral teeth.
5. A scroll compressor substantially as described with reference to any of the embodiments illustrated in Figures 1 to 3 of the accompanying drawings.