CN112567136B

CN112567136B - Scroll compressor having a discharge port

Info

Publication number: CN112567136B
Application number: CN202080004563.1A
Authority: CN
Inventors: 中井启晶; 吉田裕文; 作田淳
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2019-02-08
Filing date: 2020-02-03
Publication date: 2023-03-28
Anticipated expiration: 2040-02-03
Also published as: CN112567136A; JPWO2020162394A1; WO2020162394A1; JP7165901B2

Abstract

The invention relates to a scroll compressor, which comprises a fixed scroll, an orbiting scroll, a compression chamber and a back pressure chamber. The compression chamber has an outer compression chamber located outside the 2 nd spiral wrap of the orbiting scroll and an inner compression chamber located inside the 2 nd spiral wrap. In the middle of compression, one of the outer compression chamber and the inner compression chamber communicates with the back pressure chamber. The ratio of the suction closed volume of one compression chamber to the volume of one compression chamber at the end of communication between the one compression chamber and the back pressure chamber is set as the volume ratio of the back pressure chamber at the time of closing. The ratio between the suction closed volume and the volume of the working fluid in which the internal pressure is increased to a discharge pressure or higher and which can be discharged to the discharge path is set as a dischargeable volume ratio between the outer compression chamber and the inner compression chamber. The volume ratio of the back pressure chamber when closed is smaller than the dischargeable volume ratio of one compression chamber.

Description

Scroll compressor having a discharge port

Technical Field

The present invention relates to a scroll compressor for compressing refrigerant gas, which is used in a refrigeration apparatus such as a cooling/heating air conditioner or a refrigerator, or a heat pump type hot water supply apparatus.

Background

In a conventional scroll compressor constituting a refrigeration apparatus, a back pressure chamber is formed to press a back surface of an orbiting scroll or a fixed scroll.

An intermediate pressure hole for communicating the back pressure chamber and the compression chamber is provided in the orbiting scroll or the fixed scroll so that the pressure in the back pressure chamber becomes an intermediate pressure between the suction-side pressure and the discharge-side pressure.

An oil supply mechanism for supplying oil to a back pressure chamber by using a pressure difference between a discharge side pressure in a closed container and an intermediate pressure in the back pressure chamber is formed in a scroll compressor.

The scroll compressor is provided with a relief hole for communicating the compression chamber with the discharge side in the closed casing, and a safety valve for opening and closing the relief hole by utilizing the pressure difference between the compression chamber and the discharge side in the closed casing. The relief valve is provided at a position where the relief hole and the intermediate pressure hole intermittently communicate with each other (patent document 1).

In addition, in a scroll compressor constituting a conventional refrigeration apparatus, a flow path including an opening connected to one of a pair of compression chambers and an opening connected to a back pressure chamber is provided in an orbiting scroll or a fixed scroll.

The volume ratio of the compression chamber on the side of the passage where the opening is connected to the closed space is smaller than the volume ratio of the compression chamber on the side of the passage where the opening is not connected (patent document 2).

In either configuration, the pressure in the back pressure chamber is an intermediate pressure between the suction pressure and the discharge pressure. Since oil is supplied from the back pressure chamber to the compression chamber, the compression chamber pressure is likely to rise.

Therefore, in patent document 1, the intermediate pressure hole and the relief hole are communicated with each other, thereby preventing an over-compression state.

In patent document 2, the increase in required power due to over-compression is suppressed by adjusting the volume ratio of the compression chamber.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3584781

Patent document 2 Japanese patent No. 4693984

Disclosure of Invention

In a conventional scroll compressor, an over-compression state is prevented during operation in a state where a compression ratio (a ratio of a discharge pressure to a suction pressure) is relatively high, that is, during high-compression-ratio operation.

Avoiding the over-compression state is effective for reducing the pressure of the compression chamber, but at the same time, the pressure of the back pressure chamber also decreases, and a stable compression operation cannot be connected. Further, the scroll compressor is operated at a low compression ratio, which is a relatively slow compression ratio, by energy saving of an air conditioner, a refrigerating and oil supply device, and the like, and a rotational speed control technique of the compressor.

However, in the conventional scroll compressor, when the scroll compressor is operated at a low compression ratio, the pressing force between the orbiting scroll and the fixed scroll is lower than the pressing force from the compression chamber. Therefore, there is a problem that the orbiting scroll separates from the fixed scroll, that is, the orbiting scroll topples.

In view of the above, the present invention provides a scroll compressor capable of performing a stable compression operation without a phenomenon in which an orbiting scroll and a fixed scroll separate from each other, i.e., an overturning phenomenon, during a low compression ratio operation.

The scroll compressor of the present invention includes: a fixed scroll having a 1 st end plate and a 1 st spiral wrap; an orbiting scroll having a 2 nd end plate and a 2 nd spiral wrap; the fixed scroll is engaged with the orbiting scroll to form a compression chamber; and a back pressure chamber that holds back pressure that presses the orbiting scroll against the fixed scroll.

The compression chamber has: an outer compression chamber located outside the 2 nd spiral wrap of the orbiting scroll; and an inner compression chamber located inside the 2 nd spiral wrap of the orbiting scroll.

The back pressure chamber communicates with only the outer compression chamber or the inner compression chamber during compression.

The outer compression chamber and the inner compression chamber respectively have a suction closed volume at a time point when the closing of the working fluid is finished.

In the middle of compression, one compression chamber of the outer compression chamber and the inner compression chamber communicates with the back pressure chamber.

And setting the ratio of the suction closed volume of the one compression chamber to the volume of the one compression chamber when the one compression chamber and the back pressure chamber are communicated to each other as the volume ratio of the back pressure chamber when the back pressure chamber is closed.

The ratio between the suction closed volume and the volume of the working fluid that can be discharged to the discharge path when the internal pressure is increased to or above the discharge pressure is set as a dischargeable volume ratio for the outer compression chamber and the inner compression chamber.

The volume ratio of the back pressure chamber when closed is smaller than the dischargeable volume ratio of the one compression chamber.

With this configuration, when the compressor is operated at a low compression ratio in which the compression ratio is smaller than the volume ratio at the time of closing the back pressure chamber, the one compression chamber on the side where the back pressure chamber communicates with is over-compressed, and the back pressure chamber is also brought into an over-compressed state in conjunction with the one compression chamber.

Then, the communication between the back pressure chamber and the compression chamber is closed, and the compression chamber is reduced to the discharge pressure at the time point when the dischargeable volume ratio is reached. On the other hand, since the back pressure chamber is separated from the compression chamber, the over-compression state is maintained.

Therefore, the orbiting scroll presses the fixed scroll at a pressure of the back pressure chamber equal to or higher than the discharge pressure, and the occurrence of the overturning can be suppressed.

According to the present invention, it is possible to provide a scroll compressor which does not separate from a fixed scroll of an orbiting scroll during low compression ratio operation and performs a stable compression operation.

Drawings

Fig. 1 is a sectional view seen from a side of a scroll compressor according to an embodiment of the present invention.

Fig. 2 is an enlarged sectional view of a main portion of the compression mechanism of the scroll compressor.

Fig. 3 is a cross-sectional view of the arrows along line C-C of fig. 2.

Fig. 4 is a diagram showing the opening state of the communication passage and the injection port with the back pressure chamber in accordance with the orbiting motion of the scroll compressor.

Fig. 5 is a diagram illustrating a positional relationship between a communication path with the back pressure chamber and a sealing member, which shows the orbiting motion of the scroll compressor.

Fig. 6 is a refrigeration cycle diagram using a scroll compressor according to an embodiment of the present invention.

Fig. 7 isbase:Sub>A cross-sectional view taken along linebase:Sub>A-base:Sub>A of fig. 2.

Fig. 8 is a view in cross section taken along line B-B of fig. 7.

Detailed Description

The scroll compressor of the present invention includes: a fixed scroll having a 1 st end plate and a 1 st spiral wrap; an orbiting scroll having a 2 nd end plate and a 2 nd spiral wrap; a compression chamber formed by engaging the fixed scroll with the orbiting scroll; and a back pressure chamber that holds back pressure that presses the orbiting scroll against the fixed scroll.

The back pressure chamber is communicated with only the outer compression chamber or the inner compression chamber during compression.

One compression chamber of the outer compression chamber and the inner compression chamber communicates with the back pressure chamber in the middle of compression.

The ratio of the suction closed volume to a volume of the working fluid, the internal pressure of which is increased to a discharge pressure or higher and which can be discharged to a discharge path, is set as a dischargeable volume ratio with respect to the outer compression chamber and the inner compression chamber.

With this configuration, when the compressor is operated at a low compression ratio, in which the compression ratio is smaller than the volume ratio at the time of closing the back pressure chamber, over-compression occurs in one of the compression chambers on the side where the back pressure chamber communicates, and the back pressure chamber is also brought into an over-compression state in conjunction with the one of the compression chambers on the side where the back pressure chamber communicates. Thereafter, the communication between the back pressure chamber and one of the compression chambers is closed, and the one of the compression chambers is reduced to the discharge pressure at a point in time when the dischargeable volume ratio is reached. On the other hand, since the back pressure chamber is separated from the compression chamber, the over-compression state is maintained. Therefore, the orbiting scroll presses the fixed scroll at a pressure equal to or higher than the discharge pressure in the back pressure chamber, and the occurrence of overturning can be suppressed.

Further, the volume ratio of the closed back pressure chamber may be larger than the dischargeable volume ratio of the other compression chamber not communicating with the back pressure chamber, out of the outer compression chamber and the inner compression chamber.

Thus, the other compression chamber not communicating with the back pressure chamber is not in an over-compression state above the back pressure chamber, and the pressing force is generated by the high pressure from the back pressure chamber side, thereby realizing a stable compression operation.

Further, the suction closed volume of the outer compression chamber may be larger than the suction closed volume of the inner compression chamber, and one compression chamber on a side where the back pressure chamber communicates may be the inner compression chamber.

In this way, since the back pressure chamber is made to be in an over-compressed state, the dischargeable volume is relatively large and one compression chamber communicating with the back pressure chamber is made to be an inner compression chamber having a small volume, and the dischargeable volume of the outer compression chamber having a large volume can be ensured to be relatively small.

The pressing force on the orbiting scroll is determined by the product of the area of the compression chamber projected in a view in the pressing direction and the pressure. Thus, the compression chamber in an over-compressed state is less likely to generate a force for canceling the pressing force as the volume is smaller, and a more stable compression operation can be realized.

Further, the method may further include: a discharge chamber that discharges the working fluid that has reached a discharge pressure; a discharge port provided at a central portion of the fixed scroll; and a discharge bypass port provided in the other compression chamber not communicating with the back pressure chamber, the discharge bypass port communicating the other compression chamber with the discharge chamber at a position forward of the discharge port. Further, the dischargeable volume ratio of the other compression chamber that is not in communication with the back pressure chamber may be smaller than the dischargeable volume ratio of the one compression chamber that is in communication with the back pressure chamber by the discharge bypass port.

Thus, one compression chamber on the side communicating with the back pressure chamber communicates with the discharge port or the discharge bypass port after the communication with the back pressure chamber is closed, and is released from the over-compression state and lowered to the discharge pressure. On the other hand, the pressure of the back pressure chamber is higher than the discharge pressure because the pressure is maintained in an over-compressed state due to the absence of the drain pressure. Therefore, a pressing force acts on the orbiting scroll from the back pressure chamber side to the fixed scroll side, and the compression operation can be continued while maintaining the airtightness of the compression chamber.

Further, by including the discharge bypass port, the dischargeable volume ratio of only one of the inner compression chamber and the outer compression chamber can be arbitrarily adjusted regardless of the wrap shape of the orbiting scroll and the wrap shape of the fixed scroll, and therefore the dischargeable volume ratio of each compression chamber that realizes the present invention can be configured with respect to the volume ratio when the back pressure chamber is closed.

The back pressure chamber when the communication between the back pressure chamber and the one compression chamber is completed may be a closed space divided from another space having a pressure difference with the back pressure chamber.

Thus, a pressing force acts on the orbiting scroll from the back pressure chamber side to the fixed scroll side, and the compression operation can be continued while maintaining the airtightness of the compression chamber.

Embodiments of the present invention will be described below with reference to the drawings. In addition, the present disclosure is not limited by these embodiments.

(embodiment mode)

Fig. 1 is a sectional view of a scroll compressor according to an embodiment of the present invention, as viewed from the side, and fig. 2 is an enlarged sectional view of a main portion of a compression mechanism of the scroll compressor.

Hereinafter, the operation and action of the scroll compressor according to the present embodiment will be described.

As shown in fig. 1, a scroll compressor 91 according to the present embodiment includes a closed casing 1, a compression mechanism 2 located inside the closed casing 1, a motor unit 3 for driving the compression mechanism 2, and an oil reservoir 20 provided at the bottom of the closed casing 1.

As shown in fig. 2, the compression mechanism 2 includes, in the closed casing 1: a main bearing member 11 fixed by welding or shrink fitting; a fixed scroll 12 bolted to the main bearing member 11, the spiral wrap (1 st spiral wrap) standing upright on an end plate (1 st end plate); and an orbiting scroll 13 in which a spiral wrap (2 nd spiral wrap) stands on an end plate (2 nd end plate). The compression mechanism 2 includes: a compression chamber 15 that can mesh the fixed scroll 12 with the orbiting scroll 13; and a back pressure chamber 29 that holds pressure that presses the orbiting scroll 13 against the fixed scroll 12.

Between the orbiting scroll 13 and the main bearing member 11, a rotation restricting mechanism 14 including an oldham ring or the like is provided, and the oldham ring prevents rotation of the orbiting scroll 13 and guides the orbiting scroll to perform circular orbit motion.

The rotary shaft 4 is rotationally driven by the motor unit 3. The rotary shaft 4 is supported by a main bearing member 11, and the orbiting scroll 13 is eccentrically driven by an eccentric shaft portion 4a located at an upper end of the rotary shaft 4.

Thereby, the orbiting scroll 13 performs a circular orbit motion. The compression chamber 15 formed between the fixed scroll 12 and the orbiting scroll 13 moves from the outer peripheral side to the center while compressing the volume. By the above movement, the working fluid is sucked from a suction pipe 16 (see fig. 1) leading to the outside of the closed casing 1 and a suction port 17 in the outer peripheral portion of the fixed scroll 12, and the compression chamber 15 is closed and compressed.

The working fluid having reached a predetermined pressure pushes open a discharge reed valve 19 from a discharge port 18 provided at the center of the fixed scroll 12. The working fluid having reached the discharge pressure is discharged into the sealed container 1 through the discharge chamber 31, and is sent out of the sealed container 1 through the discharge pipe 22 (see fig. 1).

As shown in fig. 1, a pump 25 is provided at the lower end of the rotary shaft 4. The pump 25 is disposed so that its suction port is present in the oil reservoir 20. The pump 25 is driven simultaneously with the orbiting scroll 13. Thereby, the pump 25 can reliably suck up the oil 6 in the oil reservoir 20 regardless of the pressure condition and the operation speed. Therefore, no oil shortage will occur.

The oil 6 sucked up by the pump 25 is supplied to the compression mechanism 2 through an oil supply hole 26 that penetrates (penetrates) the rotary shaft 4.

Further, before or after the oil 6 is sucked up by the pump 25, foreign matter is removed from the oil 6 by an oil filter or the like, and then the foreign matter is prevented from entering the compression mechanism 2, thereby further improving the reliability.

The pressure of the oil 6 introduced into the compression mechanism 2 is substantially the same as the discharge pressure of the scroll compressor 91, and serves as a back pressure source for the orbiting scroll 13. Further, a part of the oil 6 enters a fitting portion between the eccentric shaft portion 4a and the orbiting scroll 13 and a bearing portion 66 between the rotary shaft 4 and the main bearing member 11 by the supply pressure and the own weight to seek escape, lubricates the respective portions, and then falls down to return to the oil reservoir 20.

Fig. 3 is a cross-sectional view taken along line C-C in fig. 2.

The compression chamber 15 formed by the fixed scroll 12 and the orbiting scroll 13 includes an outer compression chamber 15a located outside the lap of the orbiting scroll 13 and an inner compression chamber 15b located inside the lap.

The scroll compressor 91 is an asymmetric scroll compressor in which the suction closed volume of the outer compression chamber 15a is different from the suction closed volume of the inner compression chamber 15b.

Here, the suction closing volume is a volume of the compression chamber immediately after closing the working fluid sucked from the suction port 17. The scroll compressor 91 is an asymmetric scroll compressor in which the suction closed volume of the outer compression chamber 15a is larger than that of the inner compression chamber 15b.

By adopting the asymmetric scroll compressor, the suction closed volume of the entire compressor is increased, and therefore, the space inside the compressor can be effectively used.

The working fluid sucked through the suction port 17 can be blocked near the suction port 17 of the outer compression chamber 15a and can be subjected to the compression step. Therefore, the low-pressure and low-temperature working fluid is heated by the compression mechanism 2, and the decrease in the density of the working fluid can be suppressed.

The difference in the suction closed volume between the outer compression chamber 15a and the inner compression chamber 15b is affected by the volume ratio. The volume ratio is a ratio of a suction closed volume to a volume of the compression chamber at a certain time point in the compression process. The volume ratio can be defined for each of the outer compression chamber and the inner compression chamber.

Generally, the volumes of the inner compression chamber and the outer compression chamber are substantially equal when the chambers communicate with a discharge port 18 provided at the center of the fixed scroll 12. When the discharge port 18 is the only discharge path of the working fluid in the compression chamber, the dischargeable volume ratio of each compression chamber is determined by the suction closed volume.

Here, the dischargeable volume ratio refers to a ratio of the suction closing volume to a volume of the compression chamber at a time point when the compression chamber is dischargeable, that is, the compression chamber communicates with the discharge chamber 31. The dischargeable volume ratio can be defined for each of the outer compression chamber and the inner compression chamber.

In the present embodiment, since the suction closed volume of the outer compression chamber 15a is larger than the suction closed volume of the inner compression chamber 15b, the outer compression chamber 15a has a longer compression step and a larger dischargeable volume ratio than the inner compression chamber 15b.

During low compression ratio operation, which is operation in a relatively low compression ratio state, the outer compression chamber 15a is more likely to be in an over-compressed state than the inner compression chamber 15b. Here, the compression ratio is a ratio of the discharge pressure to the suction pressure. In addition, the outer compression chamber 15a has a larger area projected in the direction of pressing the compression chamber than the inner compression chamber 15b. Therefore, the excessive compression of the outer compression chamber 15a easily increases the force pushing the orbiting scroll 13 away from the fixed scroll 12.

Further, a wrap tip 13c (see fig. 2) of the orbiting scroll 13 is provided with a slope shape in which the wrap height gradually increases from a wrap start portion, which is a central portion, to a wrap end portion, which is an outer peripheral portion, based on a result of measuring a temperature distribution during operation. This can absorb dimensional changes due to thermal expansion and prevent local sliding.

As shown in fig. 2, the scroll compressor 91 includes a connection path 55-1 and a supply path 55-2 as an oil supply path 55 for guiding oil from the oil reservoir 20 to the compression chamber 15.

Further, the oil supply path to the compression chamber 15 includes a passage 13a formed inside the orbiting scroll 13 and a recess 12a formed in the lap-side end plate of the fixed scroll 12. The passage 13a includes a supply path 55-2.

One side opening end 55-2b of the passage 13a is formed at the wrap tip end 13c and is periodically opened in the recess 12a in cooperation with the orbiting motion. Further, the other side opening end 55-2a of the passage 13a is always opened in the back pressure chamber 29. Thus, the back pressure chamber 29 is intermittently communicated only with the inner compression chamber 15b, but is not communicated with the outer compression chamber 15a.

Further, by actively supplying the oil to the inner compression chamber 15b having a high pressure increase rate, it is possible to suppress leakage from the inner compression chamber 15b-1 (see fig. 3) formed one after another to the inner compression chamber 15b-2 (see fig. 3) formed next in the compression process.

As shown in fig. 2, a seal member 78, a high-pressure region 30 for holding the working fluid at the discharge pressure, and a back-pressure chamber 29 for holding the working fluid at an intermediate pressure between the discharge pressure and the suction pressure are provided on the back surface 13e of the orbiting scroll 13. The inside of the seal member 78 is divided into the high-pressure region 30 by the seal member 78, and the outside of the seal member 78 is divided into the back-pressure chamber 29.

At least one of the oil supply paths is configured to pass through the back pressure chamber 29. That is, the oil supply path 55 is constituted by a connection path 55-1 from the high pressure region 30 to the back pressure chamber 29 and a supply path 55-2 from the back pressure chamber 29 to the inner compression chamber 15b.

Accordingly, the orbiting scroll 13 stably presses the fixed scroll 12 by the back pressure from the back surface 13e, and the operation can be stably performed while reducing leakage of the working fluid from the back pressure chamber 29 to the compression chamber 15.

Further, by using the seal member 78, the pressure in the high-pressure region 30 and the pressure in the back pressure chamber 29 (hereinafter, back pressure) are completely separated, and the pressure application from the back surface of the orbiting scroll 13 can be stably controlled.

Further, by providing the connection path 55-1 from the high-pressure region 30 to the back pressure chamber 29, the oil 6 can be supplied to the sliding portion of the rotation restricting mechanism 14 and the thrust sliding portions of the fixed scroll 12 and the orbiting scroll 13.

Further, by providing the supply passage 55-2 from the back pressure chamber 29 to the inner compression chamber 15b, the amount of oil supplied to the inner compression chamber 15b can be positively increased, and leakage loss of the inner compression chamber 15b can be suppressed.

Further, one side open end 55-1b of the connecting path 55-1 is formed on the back surface 13e of the orbiting scroll 13, and the other side open end 55-1a is always opened in the high pressure region 30 by moving back and forth on the seal member 78. This enables the intermittent oil supply and the adjustment of the back pressure.

First, the intermittent oil supply is explained.

Fig. 5 is a diagram illustrating a positional relationship between a communication passage with the back pressure chamber and the seal member in accordance with the orbiting motion of the scroll compressor.

Fig. 5 shows the states of (I) 0 to 90 °, (II) 90 to 180 °, (III) 180 to 270 °, and (IV) 270 to 360 °, in which the phases are shifted by 90 degrees at a time.

That is, fig. 5 (II) shows a state rotated 90 degrees from the rotation shaft 4 of fig. 5 (I), fig. 5 (III) shows a state rotated 90 degrees from fig. 5 (II), fig. 5 (IV) shows a state rotated 90 degrees from fig. 5 (III), and fig. 5 (I) shows a state further rotated 90 degrees from fig. 5 (IV).

As shown in fig. 5, one side open end 55-1b of the connecting path 55-1 is located on the back face 13e of the orbiting scroll 13. The back surface 13e of the orbiting scroll 13 is partitioned into an inner high-pressure region 30 and an outer back-pressure chamber 29 by a seal member 78.

In the state of fig. 5 (II), one side opening end 55-1b opens to the outside of the sealing member 78, i.e., the back pressure chamber 29. Therefore, the back pressure chamber 29 communicates with the high pressure region 30. Thereby, the oil 6 is supplied from the high-pressure region 30 to the back pressure chamber 29.

In contrast, in the states of fig. 5 (I), (III), and (IV), the open end 55-1b opens inside the sealing member 78. Therefore, the back pressure chamber 29 does not communicate with the high pressure region 30. Therefore, the oil 6 is not supplied from the high-pressure region 30 to the back pressure chamber 29.

That is, the one-side open end 55-1b of the connection path 55-1 moves back and forth between the high-pressure region 30 and the back-pressure chamber 29, and the oil 6 is supplied to the back-pressure chamber 29 only when a pressure difference is generated between the open ends 55-1a and 55-1b on both sides of the connection path 55-1. Thus, the amount of oil supply is adjusted by the time ratio of the one side open end 55-1b moving back and forth on the sealing member 78. Therefore, the passage of the connection passage 55-1 can be formed in a size 10 times or more as large as the oil filter.

Further, there is no possibility that the passage is engaged with and clogged with a foreign matter, back pressure can be stably applied, and lubrication of the thrust sliding portion and the rotation restricting mechanism 14 can be maintained in a good state, and high efficiency and high reliability can be achieved.

In the above description, the case where the other side open end 55-1a is always located in the high pressure region 30 and the one side open end 55-1b moves back and forth between the high pressure region 30 and the back pressure chamber 29 is described as an example. The present invention is not limited to this example, and for example, even when the other-side open end 55-1a moves back and forth between the high-pressure region 30 and the back pressure chamber 29 and the one-side open end 55-1b is always positioned in the back pressure chamber 29, a pressure difference is generated between the open ends 55-1a and 55-1b, so that intermittent oil supply can be realized and the same effect can be obtained.

Next, the adjustment of the back pressure will be described.

Fig. 4 is a diagram showing the opening state of the communication path with the back pressure chamber and the injection port in accordance with the orbiting motion of the scroll compressor.

Fig. 4 is a diagram in which the fixed scroll 12 and the orbiting scroll 13 are engaged with each other and the phase is shifted by 90 degrees at a time when viewed from the back surface 13e of the orbiting scroll 13. Fig. 4 shows the states of (I) 0 ° to 90 °, (II) 90 ° to 180 °, (III) 180 ° to 270 °, and (IV) 270 ° to 360 °, as in fig. 5.

That is, fig. 4 (II) shows a state rotated 90 degrees from the rotation shaft 4 of fig. 4 (I), fig. 4 (III) shows a state rotated 90 degrees from fig. 4 (II), fig. 4 (IV) shows a state rotated 90 degrees further from fig. 4 (III), and fig. 4 (I) shows a state rotated 90 degrees further from fig. 4 (IV).

The state shown in fig. 4 (I) is where the outer compression chamber 15a is located at a position where the working fluid is closed, and the state shown in fig. 4 (III) is where the inner compression chamber 15b is located at a position where the working fluid is closed.

In the state shown in fig. 4 (I), 2 outer compression chambers 15a are formed. The outer compression chamber 15a located on the outer peripheral side is in a low-pressure state immediately after the working fluid is sealed, and the outer compression chamber 15a located on the inner peripheral side is in an intermediate-pressure state.

In the state shown in fig. 4 (II), the outer compression chamber 15a formed on the inner peripheral side is in a high-pressure state before discharge.

In the state shown in fig. 4 (III), 2 inner compression chambers 15b are formed, the inner compression chamber 15b located on the outer peripheral side is in a low-pressure state immediately after the working fluid is sealed, and the inner compression chamber 15b located on the inner peripheral side is in an intermediate-pressure state.

In the state shown in fig. 4 (IV), the inner compression chamber 15b formed on the inner peripheral side is in a high-pressure state before discharge.

First, a case of the high compression ratio operation will be described.

In the state of fig. 4 (IV), one side opening end 55-2b is opened in the recess 12a. Therefore, the inner compression chamber 15b communicates with the back pressure chamber 29. During high compression ratio operation, the oil 6 is supplied from the back pressure chamber 29 to the inner compression chamber 15b through the supply passage 55-2 and the passage 13a (see fig. 2).

The concave portion 12a is provided at a position where the one open end 55-2b is opened immediately after the working fluid (also referred to as a suction refrigerant) sucked into the inner compression chamber 15b is closed (see fig. 4 (IV)). In other words, the oil supply path is provided at a position opened to the inner compression chamber 15b in the compression process after the refrigerant is sucked in and closed by the one open end 55-2 b. Therefore, the pressure of the back pressure chamber 29 during communication with the inner compression chamber 15b is substantially equal to the pressure of the inner compression chamber 15b.

In contrast, in the states of fig. 4 (I), (II), and (III), the one-side opening end 55-2b is not opened in the recess 12a. Therefore, the oil 6 is not supplied from the back pressure chamber 29 to the inner compression chamber 15b. The pressure of the back pressure chamber 29 is not affected by the inner compression chamber 15b.

As described above, in the state of fig. 5 (II) corresponding to fig. 4 (II), the back pressure chamber 29 communicates with the high pressure region 30. Thus, the pressure of the back pressure chamber 29 is the same as the pressure of the high pressure region 30, that is, the discharge pressure.

That is, during high compression ratio operation, the back pressure chamber 29 is adjusted to a pressure state intermediate between the suction pressure and the discharge pressure, and this pressure acts as a pressing force to the orbiting scroll during low compression ratio operation.

Next, a case of the low compression ratio operation will be described.

In the low compression ratio operation, in the state of fig. 4 (IV), the pressure of the inner compression chamber 15b communicating with the back pressure chamber 29 and located on the outer peripheral side is increased to a pressure equal to or higher than the discharge pressure, and the back pressure chamber 29 is also set to a pressure equal to or higher than the discharge pressure.

In the state of fig. 5 (IV), the back pressure chamber 29 is not communicated with the high pressure region 30, and the space formed by the inner compression chamber 15b and the back pressure chamber 29 is a closed space. Therefore, the back pressure chamber 29 is in a higher pressure state than the high pressure region 30 equal to the discharge pressure.

The compression step is further performed such that when the open end 55-2b of the back pressure chamber 29 communicating with the inner compression chamber 15b is separated from the recess 12a, the back pressure chamber 29 becomes an independent closed space. Therefore, the pressure of the back pressure chamber 29 does not depend on the pressure of the inner compression chamber 15b and the pressure of the high pressure region 30. When the compression is performed to the dischargeable volume ratio or more, the working fluid in the compression chamber is discharged to the discharge chamber 31, and the pressure of the inner compression chamber 15b decreases to the discharge pressure. On the other hand, the pressure in the back pressure chamber 29 is maintained in an over-compression state when the back pressure chamber 29 is separated from the inner compression chamber 15b until the back pressure chamber 29 communicates with the inner compression chamber 15b or the high pressure region 30.

That is, in the low compression ratio operation, in the state of fig. 4 (I) and 5 (I), only the back pressure chamber 29 maintains a pressure state higher than the discharge pressure, and this pressure acts as a pressing force to the orbiting scroll.

In addition to the discharge port 18, the scroll compressor 91 is provided with a discharge bypass port 21 (see fig. 2) as a passage for guiding the working fluid compressed in the compression chamber 15 to the discharge chamber 31.

The discharge bypass port 21 includes a reed valve as in the discharge port 18. When the pressure in the compression chamber 15 reaches the pressure in the discharge chamber 31, the reed valve is pushed open, and the working fluid is discharged to the discharge chamber 31. When the pressure in the compression chamber 15 is lower than the pressure in the discharge chamber 31, the reed valve closes, and the backflow of the working fluid from the discharge chamber 31 to the compression chamber 15 can be suppressed.

However, as a condition that the discharge bypass port 21 fulfills the above function, the discharge bypass port 21 needs to be present at a position communicating with the compression chamber 15. The discharge bypass port 21 is a fixed passage provided in an end plate of the fixed scroll 12.

The compression chamber 15 moves toward the center side while reducing its volume together with the compression operation, and the working fluid in the compression chamber 15 can be discharged to the discharge chamber 31 only when the compression chamber 15 reaches a position communicating with the discharge port 18 or the discharge bypass port 21.

The discharge bypass port 21 is provided to allow the discharge chamber 31 to communicate with the compression chamber 15 before communicating with the discharge chamber 31 in the compression process through the discharge port 18.

As shown in fig. 4, the scroll compressor 91 is provided with a discharge bypass port 21a communicating with the outer compression chamber 15a and a discharge bypass port 21b communicating with the inner compression chamber 15b, respectively, thereby missing timing of communication.

The discharge bypass port 21a is not in communication with the outer compression chamber 15a in the state of fig. 4 (I), and is provided at a position in communication with the outer compression chamber 15a located on the outer peripheral side in the states of fig. 4 (II) to (IV).

The discharge bypass port 21b is not communicated with the inner compression chamber 15b in the state (IV) of fig. 4, and is provided in a position communicated with the inner compression chamber 15b located on the outer peripheral side in the states (I) to (III) of fig. 4.

The outer compression chamber 15a ends the suction process at the time (I) of fig. 4, and the inside of the outer compression chamber 15a is closed. In fig. 4 (II) in which the compression process is performed at 90 °, the outer compression chamber 15a and the discharge bypass port 21a are already in a communicated state. In this case, the dischargeable volume ratio of the outer compression chamber 15a is determined by the ratio of the suction closed volume of the outer compression chamber 15a to the compression chamber volume at the time when the outer compression chamber 15a communicates with the discharge bypass port 21a, and does not substantially depend on the timing of communication with the discharge port 18.

On the other hand, the inner compression chamber 15b ends the suction process at the time (III) of fig. 4, and the inside of the inner compression chamber 15b is closed. In fig. 4 (IV) in which the compression process is performed at 90 °, the inner compression chamber 15b is not communicated with the discharge bypass port 21 b. In fig. 4 (I) further performed by 90 °, the inner compression chamber 15b communicates with the discharge bypass port 21 b. Further, at the time of fig. 4 (IV), the inner compression chamber 15b communicates with the back pressure chamber 29 via the supply path 55-2 and the passage 13 a.

In this case, the dischargeable volume ratio of the inner compression chamber 15b is also determined by the timing of communication with the discharge bypass port 21 b. The dischargeable volume ratio of the inner compression chamber 15b communicating with the back pressure chamber 29 is larger than the dischargeable volume ratio of the outer compression chamber 15a and the volume ratio of the back pressure chamber when closed.

Here, the volume ratio when the back pressure chamber is closed means: in the inner compression chamber 15b, which is the compression chamber on the side where the back pressure chamber 29 communicates, the ratio of the suction closed volume to the volume of the inner compression chamber 15b on the outer peripheral side at the time when the communication between the back pressure chamber 29 and the inner compression chamber 15b in the middle of compression is completed (that is, at the time after (IV) in fig. 4).

With this configuration, even if the pressure in the compression chamber 15 reaches the discharge pressure at an early timing during the low compression ratio operation, the outer compression chamber 15a having a large projected area is not over-compressed, and the working fluid can be discharged into the discharge chamber 31.

On the contrary, the inner compression chamber 15b is over-compressed, and the pressure thereof is also transmitted to the back pressure chamber 29, thereby increasing the pressing force of the orbiting scroll 13. After the communication between the inner compression chamber 15b and the back pressure chamber 29 is completed, the pressure of the back pressure chamber 29 in an over-compression state is maintained.

On the other hand, the overcompression of the inner compression chamber 15b is eliminated by the communication with the discharge bypass port 21 b. This can suppress a force from the compression chamber 15 side acting in a direction of pulling the orbiting scroll 13 away from the fixed scroll 12, and can continue the compression operation while stably pressing the orbiting scroll 13 against the fixed scroll 12 by applying a strong pressing force to the back face 13e of the orbiting scroll.

Next, a refrigeration cycle apparatus using the scroll compressor 91 will be described.

Fig. 6 is a view of a refrigeration cycle using a scroll compressor according to an embodiment of the present invention.

As shown in fig. 6, the refrigeration cycle device includes: a scroll compressor 91, a condenser 92, an evaporator 93, two pressure reducers 94, an injection pipe 95, and a gas-liquid separator 96. The scroll compressor 91, the condenser 92, the upstream decompressor 94a, the gas-liquid separator 96, and the downstream decompressor 94b are annularly connected by pipes. The injection pipe 95 connects the gas-liquid separator 96 with the scroll compressor 91.

The working fluid (hereinafter also referred to as a refrigerant) condensed in the condenser 92 is decompressed to an intermediate pressure by the upstream decompressor 94a, and flows into the gas-liquid separator 96. The gas-liquid separator 96 separates the medium-pressure refrigerant into a gas-phase component (gas refrigerant) and a liquid-phase component (liquid refrigerant). The intermediate-pressure liquid refrigerant passes through the downstream-side decompressor 94 again, becomes a low-pressure refrigerant, and flows into the evaporator 93.

The liquid refrigerant flowing into the evaporator 93 is evaporated by heat exchange, and the gas refrigerant or a part of the gas refrigerant mixed with the liquid refrigerant is discharged. The refrigerant discharged from the evaporator 93 flows into the compression chamber 15 of the scroll compressor 91.

On the other hand, the intermediate-pressure gas refrigerant separated by the gas-liquid separator 96 is injected (injected) into the compression chamber 15 in the scroll compressor 91 through the injection pipe 95. The injection pipe 95 may be provided with a mechanism for adjusting and stopping the pressure for injection, such as a closing valve or a pressure reducer 94.

In the scroll compressor 91, during compression of the low-pressure refrigerant flowing in from the evaporator 93, the intermediate-pressure refrigerant of the gas-liquid separator 96 is injected into the compression chamber 15 to compress the refrigerant, and the high-temperature and high-pressure refrigerant is discharged from the discharge pipe 22 (see fig. 1) to the condenser 92.

The ratio of the gas phase component to the liquid phase component of the refrigerant separated by the gas-liquid separator 96 will be described.

The gas phase component increases as the pressure difference between the inlet-side pressure and the outlet-side pressure of the upstream expansion valve (pressure reducer 94 a) increases. The gas phase component increases as the degree of subcooling or the degree of dryness of the refrigerant at the outlet of the condenser 92 decreases.

On the other hand, the amount of refrigerant sucked by the scroll compressor 91 through the injection pipe 95 is increased as the intermediate pressure is higher. When the refrigerant having a higher gas-phase component ratio than the refrigerant separated in the gas-liquid separator 96 is sucked in from the injection pipe 95, the gas refrigerant in the gas-liquid separator 96 is consumed, and the liquid refrigerant flows into the injection pipe 95.

In order to maximize the capacity of the scroll compressor 91, it is desirable that the gas refrigerant separated in the gas-liquid separator 96 be completely sucked into the scroll compressor 91 from the injection pipe 95. If the refrigerant deviates from the equilibrium state, the liquid refrigerant flows into the scroll compressor 91 from the injection pipe 95. Therefore, even when the liquid refrigerant flows into the injection pipe 95, the scroll compressor 91 needs to be configured to maintain high reliability.

Fig. 7 isbase:Sub>A cross-sectional view taken along linebase:Sub>A-base:Sub>A of fig. 2. Fig. 8 is a cross-sectional view taken along line B-B of fig. 7.

At the intermediate pressure of the inflow from the injection pipe 95, as shown in fig. 1, 2, 7, and 8, the refrigerant flows into the intermediate pressure chamber 41, opens the check valve 42 provided at the injection port 43, and is injected into the closed compression chamber 15. The injected refrigerant is discharged into the sealed container 1 from the discharge port 18 together with the refrigerant sucked in from the suction port 17.

An injection port 43 for injecting the intermediate-pressure refrigerant is provided to penetrate the end plate of the fixed scroll 12. The inlet 43 is opened in the outer compression chamber 15a and the inner compression chamber 15b in this order. The injection port 43 is provided at a position opened in each of the outer compression chambers 15a and the inner compression chambers 15b in the compression process after the closing of the compression chambers.

As shown in fig. 1 and 2, the scroll compressor 91 is provided with an intermediate pressure chamber 41, and the intermediate pressure chamber 41 guides the intermediate pressure working fluid sent from the injection pipe 95 before being injected into the compression chamber 15.

The intermediate pressure chamber 41 is formed by the fixed scroll 12, an intermediate pressure plate 44, and an intermediate pressure cover 45 (see fig. 2) as compression chamber partition members. The intermediate pressure chamber 41 and the compression chamber 15 are opposed to each other across the fixed scroll 12.

The intermediate pressure chamber 41 has: an intermediate pressure chamber inlet 41a into which the intermediate pressure working fluid flows; an inlet port 43a for injecting the intermediate pressure working fluid into the inlet port 43 of the compression chamber 15; and a liquid storage portion 41b formed at a position lower than the intermediate pressure chamber inlet 41 a.

The liquid reservoir 41b is formed by the upper surface of the end plate of the fixed scroll 12.

The intermediate pressure plate 44 is provided with a check valve 42 that prevents the refrigerant from flowing backward from the compression chamber 15 to the intermediate pressure chamber 41. In the section where the compression chamber 15 is open, when the internal pressure of the compression chamber 15 is higher than the intermediate pressure of the injection port 43, the refrigerant flows backward from the compression chamber 15 to the intermediate pressure chamber 41. By providing the check valve 42 in this manner, the backflow of the refrigerant can be prevented.

In the scroll compressor 91 of the present embodiment, the check valve 42 is lifted up to the compression chamber 15 side, and is constituted by the reed valve 42a that communicates the compression chamber 15 with the intermediate pressure chamber 41. Thus, the intermediate pressure chamber 41 can be communicated with the compression chamber 15 only when the internal pressure of the compression chamber 15 is lower than the pressure of the intermediate pressure chamber 41.

By using the reed valve 42a, the number of sliding portions in the movable portion is small, the sealing performance can be maintained in the long term, and the flow path area can be easily enlarged as necessary.

When the check valve 42 is not provided, or when the check valve 42 is provided in the injection pipe 95, the refrigerant in the compression chamber 15 flows back to the injection pipe 95, and useless compression power is consumed. In the present embodiment, the check valve 42 is provided in the intermediate pressure plate 44 near the compression chamber 15, thereby suppressing the reverse flow from the compression chamber 15.

The upper surface of the end plate of the fixed scroll 12 is located lower than the intermediate pressure chamber inlet 41 a. A liquid reservoir 41b for storing a refrigerant of a liquid phase component is provided on the upper surface of the end plate of the fixed scroll 12.

The inlet port 43a is provided at a position higher than the height of the intermediate pressure chamber inlet 41 a. Therefore, the refrigerant of the gas phase component in the intermediate-pressure working fluid is guided to the injection port 43, and the refrigerant of the liquid phase component stored in the liquid storage portion 41b is vaporized on the surface of the fixed scroll 12 in a high-temperature state, so that the refrigerant of the liquid phase component is hard to flow into the compression chamber 15.

The intermediate pressure chamber 41 and the discharge chamber 31 are provided at positions adjacent to each other with the intermediate platen 44 interposed therebetween. This promotes vaporization of the liquid-phase working fluid when it flows into the intermediate pressure chamber 41, and suppresses a temperature increase of the high-pressure refrigerant in the discharge chamber 31. Therefore, only this portion can be operated under the high discharge pressure condition.

The intermediate-pressure refrigerant introduced into the injection port 43 pushes open the reed valve 42a by the pressure difference between the injection port 43 and the compression chamber 15, and merges with the low-pressure refrigerant sucked from the suction port 17 in the compression chamber 15.

The intermediate-pressure refrigerant remaining at the inlet 43 between the check valve 42 and the compression chamber 15 repeats re-expansion and re-compression, and therefore, the efficiency of the scroll compressor 91 is lowered. Therefore, the thickness of the valve stopper 42b that restricts the maximum displacement amount of the reed valve 42a is changed according to the lift restricting portion of the reed valve 42a, and the volume of the inside of the injection port 43 downstream of the reed valve 42a is made smaller.

Further, the reed valve 42a and the valve stopper 42b are fixed to the intermediate pressure plate 44 by bolts 48 as fixing members. The fixing holes of the bolts 48 provided in the valve stop 42b do not pass through the valve stop 42b, and are opened only at the insertion side of the bolts 48. Therefore, as a result, the fixing member 48 is configured to be opened only in the intermediate pressure chamber 41. This can suppress leakage of the working fluid between the intermediate pressure chamber 41 and the compression chamber 15 through the gap between the fixing members 48, thereby improving the injection rate.

The volume of the intermediate pressure chamber 41 is equal to or greater than the suction volume of the compression chamber 15 so that the injection amount into the compression chamber 15 can be sufficiently supplied. The suction volume here refers to the volume of the compression chamber 15 at the time point when the working fluid introduced from the suction port 17 is confined in the compression chamber 15, that is, at the time point when the suction process is completed, and the total volume of the outer compression chamber 15a and the inner compression chamber 15b.

In the scroll compressor 91 of the present embodiment, the intermediate pressure chamber 41 is provided so as to extend on the plane of the end plate of the fixed scroll 12, thereby increasing the capacity.

However, when a part of the oil 6 sealed in the scroll compressor 91 comes out of the scroll compressor 91 together with the discharge refrigerant and returns from the gas-liquid separator 96 to the intermediate pressure chamber 41 through the injection pipe 95, the oil 6 remaining in the liquid storage portion 41b becomes excessive, which causes a problem that the oil 6 in the oil storage portion 20 becomes insufficient. Therefore, the volume of the intermediate pressure chamber 41 is too large. In view of this, it is preferable that the volume of the intermediate pressure chamber 41 is equal to or greater than the suction volume of the compression chamber 15 and equal to or less than 1/2 of the lubricating oil volume of the lubricating oil 6 enclosed therein.

As shown in fig. 4, the injection port 43 is provided at a position that opens into the 1 st compression chamber (outer compression chamber 15 a) and the 2 nd compression chamber (inner compression chamber 15 b) in this order. Further, as shown in fig. 4 (II) and (III), an injection port 43 is provided so as to penetrate through the end plate of the fixed scroll 12 at a position where the outer compression chamber 15a is opened during a compression stroke after closing the suction refrigerant, or at a position where the inner compression chamber 15b is opened during a compression stroke after closing the suction refrigerant, as shown in fig. 4 (I).

In the present embodiment, the oil supply path is used as the communication path between the compression chamber and the back pressure chamber, but the same effect can be obtained by providing an independent path, which is different from the oil supply path. The back pressure chamber is not limited to the back side of the orbiting scroll, and may be provided on the back side of the fixed scroll so that the fixed scroll presses the orbiting scroll. In the present embodiment, the description has been made using a scroll compressor having an injection pipe, but the scroll compressor may be a scroll compressor not provided with an injection pipe.

Industrial applicability of the invention

The scroll compressor of the present invention is used in a cooling apparatus such as a cooling/heating air conditioner or a refrigerator, or a heat pump type hot water supply apparatus.

Description of the reference numerals

1. Closed container

2. Compression mechanism

3. Motor part

4. Shaft

4a eccentric shaft part

6. Oil(s)

11. Main bearing component

12. Fixed scroll

12a recess

13. Orbiting scroll

13a path

13c scroll wrap front end

13e back side

14. Rotation limiting mechanism

15. Compression chamber

15a outer compression chamber

15b, 15b-1, 15b-2 inner side compression chamber

16. Suction pipe

17. Suction inlet

18. Discharge port

19. Discharge reed valve

20. Oil storage part

21. 21a, 21b discharge bypass port

22. Discharge pipe

25. Pump and method of operating the same

26. Oil supply hole

29. Back pressure chamber

30. High pressure region

31. Discharge chamber

41. Intermediate pressure chamber

41a intermediate pressure chamber inlet

41b liquid storage part

42. Check valve

42a reed valve

42b valve stop

43. Injection port

43a inlet of injection port

44. Intermediate pressure plate (intermediate pressure chamber partition wall component)

45. Middle gland (middle pressure chamber partition wall component)

48. Bolt (fixed parts)

55. Oil supply path

55-1 connection path

55-1a other side open end (high pressure area side)

55-1b one side open end (backpressure chamber side)

55-2 supply path

55-2a another side open end (backpressure chamber side)

55-2b one side open end (compression chamber side)

66. Bearing part

78. Sealing member

91. Scroll compressor having a discharge port

92. Condenser

93. Evaporator with a heat exchanger

94. 94a, 94b pressure reducers

95. Injection tube

96. A gas-liquid separator.

Claims

1. A scroll compressor, comprising:

a fixed scroll having a 1 st end plate and a 1 st spiral wrap;

an orbiting scroll having a 2 nd end plate and a 2 nd spiral wrap;

a compression chamber formed by meshing the fixed scroll and the orbiting scroll; and

a back pressure chamber for maintaining back pressure for pressing the orbiting scroll to the fixed scroll,

the compression chamber has: an outer compression chamber located outside the 2 nd spiral wrap of the orbiting scroll; and an inner compression chamber located inside the 2 nd spiral wrap of the orbiting scroll,

the back pressure chamber communicates with only the inner compression chamber in the middle of compression,

the outer compression chamber and the inner compression chamber respectively have a suction closed volume when closing the working fluid is finished,

the suction closed volume of the outer compression chamber is larger than the suction closed volume of the inner compression chamber,

the inner compression chamber communicates with the back pressure chamber in the middle of compression,

setting a ratio of the suction closed volume of the inner compression chamber to the volume of the inner compression chamber at the end of communication between the inner compression chamber and the back pressure chamber as a back pressure chamber closed volume ratio,

when the ratio of the suction closed volume to the volume of the working fluid whose internal pressure is increased to or above a discharge pressure and which can be discharged to a discharge path is set as a dischargeable volume ratio with respect to the outer compression chamber and the inner compression chamber,

the volume ratio of the back pressure chamber when closed is smaller than the dischargeable volume ratio of the inner compression chamber and larger than the dischargeable volume ratio of the outer compression chamber.

2. The scroll compressor of claim 1, comprising:

a discharge chamber that discharges the working fluid that has reached the discharge pressure;

a discharge port provided at a central portion of the fixed scroll; and

a discharge bypass port provided in the outer compression chamber and communicating the outer compression chamber with the discharge chamber prior to the discharge port,

with the discharge bypass port, the dischargeable volume ratio of the outer compression chamber is made smaller than the dischargeable volume of the inner compression chamber.

3. A scroll compressor as set forth in claim 1 or 2, wherein:

the back pressure chamber when the communication between the back pressure chamber and the inner compression chamber is completed is a closed space defined by another space having a pressure difference with the back pressure chamber.