JPH0452875B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a scroll compressor.

[Prior Art] A scroll compressor has an orbiting scroll and a fixed scroll each having a mirror sail and a wrap that stands upright on the mirror plate and is formed with an involute or a curve close to an involute, and meshes with each other toward the inside of the wrap. This is housed inside a housing that has a suction port, and an Oldham ring that prevents rotation of the orbiting scroll is interposed between the orbiting scroll and the frame or fixed scroll, and the crankshaft is engaged with the orbiting scroll, and the crankshaft is connected to the orbiting scroll. Therefore, the orbiting scroll is rotated so as not to rotate on its own axis, and the sucked gas is compressed in a closed space (compression chamber) formed by both scrolls, and then discharged from the discharge port in the center of the fixed scroll.

In a scroll compressor, the orbiting scroll tends to be pulled away from the fixed scroll in the axial direction by the action of compressed gas, so in order to ensure axial sealing between both scrolls, the orbiting scroll is pulled away from the fixed scroll in the axial direction. Conventionally, applying an axial pressing force to the orbiting scroll to press the
It is being done.

As an example, U.S. Pat. No. 3,884,599 discloses applying discharge gas pressure to the back side of an orbiting scroll;
As described in Japanese Patent No. 119412, there is a system in which gas pressure in a compression chamber is applied to a rear chamber on the back surface of an orbiting scroll through small holes to apply an axial pressing force to the orbiting scroll.

In addition, Japanese Patent Application Laid-open No. 55-107093 discloses that the rear chamber on the rear side of the orbiting scroll and the inside of the compressor housing are maintained at an intermediate pressure between the suction pressure and the discharge pressure, and the orbiting scroll is pressed at the intermediate pressure in the rear chamber. A scroll compressor is disclosed that is configured to obtain power and supply oil from an oil reservoir in the housing to an oil chamber in a connecting portion between the crankshaft and the orbiting scroll via an eccentric oil supply path in the crankshaft.

[Problems to be Solved by the Invention] In the scroll compressor disclosed in U.S. Pat. The crank portion is engaged with a sliding bearing provided on the orbiting scroll. In order to maintain sealing between the orbiting scroll and the fixed scroll in the axial direction, discharge pressure is introduced into a space located on the back side of the orbiting scroll. Since only the discharge pressure is introduced into the space on the back side of the orbiting scroll in this way, the axial pressing force acting on the orbiting scroll depends only on the discharge pressure.

By the way, if the discharge pressure is constant and the suction pressure changes, the pressure in the compression chamber during the compression stroke will also change accordingly, so the force that attempts to separate the orbiting scroll from the fixed scroll will also change in approximately proportion to the suction pressure. Therefore, for example, when the suction pressure decreases, the pulling force becomes smaller, but in this case, in the case of the above-mentioned US patent disclosure,
The axial pressing force becomes excessive. Conversely, if the suction pressure becomes high, the pressing force will be insufficient and proper axial sealing will not be maintained.

As described above, the configuration disclosed in the above-mentioned US patent has a drawback in that it is not possible to maintain an appropriate axial pressing force in response to changes in suction pressure.

Japanese Patent Application Laid-Open No. 53-119412 discloses a basic invention in which a pressure intermediate between suction pressure and discharge pressure is used to press the orbiting scroll in the axial direction.

Further, although JP-A-55-107093 discloses a scroll compressor having the above configuration, since the centrifugal pump action of the eccentric oil supply path in the crankshaft is small, the scroll compressor described in the publication is In this case, the pressure in the oil chamber in the connection between the crankshaft and the orbiting scroll is substantially equal to the intermediate pressure filled in the housing acting on the oil sump,
Therefore, the entire pressing force against the orbiting scroll due to the pressure in the back chamber and the oil chamber becomes a pressing force due only to the intermediate pressure.

By the way, the force that tries to pull the orbiting scroll away from the fixed scroll in the axial direction is expressed as the sum of the products of the area and the pressure in each compression chamber between both scrolls.On the other hand, the pressing force by the back chamber is It is expressed as the product of the area of and the pressure of the back chamber. Therefore, JP-A-55-107093
As disclosed in the publication, if pressing force is obtained only by applying intermediate pressure to the back side of the orbiting scroll, if the discharge pressure changes during operation, the pressure in the compression chamber communicating with the discharge port will change. Therefore, the force trying to pull it apart changes accordingly (increases or decreases), while the pressure on the back side remains the same unless the position of the small hole is changed, so the pressing force does not change.

In this way, if you try to obtain a pushing force by applying intermediate pressure to the back side of the orbiting scroll, if the discharge pressure fluctuates, the ratio of the pulling force to the pushing force will change, and the pushing force will change. In other words, it becomes impossible to maintain a stable axial pressing force within a predetermined ratio range than the force that tries to pull it apart.

An object of the present invention is to make the axial pressing force change in accordance with fluctuations in suction pressure, and to change the axial pressing force in accordance with fluctuations in discharge pressure, thereby achieving stable axial direction. An object of the present invention is to provide a scroll compressor that can apply pressing force to an orbiting scroll.

[Means for Solving the Problems] The present invention provides a fixed scroll having an upright lap on an end plate having a discharge port in the center thereof;
an orbiting scroll having an upright lap on its end plate and combined with a fixed scroll so that the laps mesh with each other; a crankshaft connected to the side of the end plate of the orbiting scroll opposite to the lap via a bearing;
A bearing that is attached to the frame and rotatably supports the crankshaft, an anti-rotation member that prevents the orbiting scroll from rotating, an electric motor that rotationally drives the crankshaft, and a housing that houses all of the above elements. The discharged gas from the discharge port in the center of the end plate of the fixed scroll is discharged into the housing and then flows out of the housing, and the discharged gas pressure acts on the oil surface of the oil reservoir inside the housing. In the scroll compressor, there are a first back chamber defined on the outer peripheral side and a second back chamber defined in the center on the opposite wrap side of the end plate of the orbiting scroll. The chamber is maintained at a pressure intermediate between the suction gas pressure and the discharge gas pressure by communicating with a closed space formed between the fixed and rotating scrolls during compression,
The second back chamber is maintained at a pressure substantially equal to the discharge gas pressure by being connected to the oil reservoir, and the pressure in the first and second back chambers causes the orbiting scroll to move relative to the fixed scroll. It is characterized in that it obtains pressing force.

[Function] With the above configuration, the first back chamber on the back side of the orbiting scroll communicates with the compression chamber formed between both scrolls during compression, so that the suction pressure and the discharge pressure can be adjusted. An intermediate pressure (referred to as intermediate pressure) acts on the second back chamber, and a pressure substantially equal to the discharge pressure acts on the second back chamber. When the discharge pressure fluctuates, the pressure in the second back chamber changes in proportion to the variation in the discharge pressure. On the other hand, since the intermediate pressure acts on the first back chamber as described above, the pressure in the first back chamber does not follow fluctuations in the discharge pressure.
Changes according to fluctuations in suction pressure.

As a result, the axial pressing force applied to the orbiting scroll changes to follow not only changes in suction pressure but also changes in the force that tries to separate both scrolls from each other caused by fluctuations in discharge pressure.
A stable and appropriate axial pressing force can be maintained even when the discharge pressure fluctuates.

[Example] The following is a first example of the scroll compressor of the present invention.
This will be explained with reference to FIGS.

1 is a housing, 2 is a fixed scroll, and 3 is an orbiting scroll. The fixed scroll 2 and the orbiting scroll 3 each include disk-shaped end plates 4 and 5 and spiral wraps 6 and 7 formed upright thereon, and are engaged with each other with these wraps 6 and 7 facing inward. ing. A sliding bearing 8 is mounted on a boss portion of the orbiting scroll 3 that protrudes from the lower surface of the end plate. A crank portion 9b that is eccentric with respect to the center of a shaft portion 9a of a crankshaft 9 engages with this slide bearing 8. A shaft portion 9a of the crankshaft 9 is supported by an upper sliding bearing 11 and a lower sliding bearing 12 mounted on a frame 10. The crankshaft 9 is rotated by an electric motor 13. As the crankshaft 9 rotates, the orbiting scroll 3 rotates while being prevented from rotating by the Oldham ring 14 and the Oldham key 15. Due to this movement, the gas sucked from the suction pipe 16 is compressed inside the closed space (compression chamber) formed by the orbiting scroll 3 and the fixed scroll 2, and the gas is compressed inside the closed space (compression chamber) formed by the orbiting scroll 3 and the fixed scroll 2. is released into the housing 1 from the fixed scroll 2
and the electric motor 1 through a passage in the side of the frame 10.
3 and is discharged from the discharge pipe 18 to the outside of the housing 1. Therefore, housing 1
The inside is maintained at a discharge pressure atmosphere. Due to the compression reaction force of the gas confined in the compression chamber, it passes through the orbiting scroll 3, the plain bearing 8, and the crank part 9b of the crankshaft 9 to the shaft part 9a.
All loads acting on the bearings 11 and 12 are received by the bearings 11 and 12. An eccentric oil supply passage 19 is provided in the crankshaft 9, and the eccentricity of the passage 19 increases with respect to the center of the shaft portion 9a toward the top thereof. This eccentric oil supply path 19 is connected to the crankshaft 9
The oil in the oil pool at the bottom of the housing 1 is sucked up by the centrifugal pump action, and
1 and 12.

The oil supply structure for each bearing 8, 11, 12 will be explained with reference to FIGS. 2 and 3.

Lubricating the sliding bearing 8 of the orbiting scroll 3 is performed as follows. That is, the oil in the oil reservoir at the bottom of the housing 1 is transferred to the crank part of the crankshaft 9 by the discharge gas pressure acting on the oil level in the oil reservoir at the bottom of the housing 1 and the centrifugal pump action of the eccentric oil supply path 19. The upper end of 9b and the sliding bearing 8
and the upper bottom surface of the end plate boss portion of the orbiting scroll 3. The oil chamber 20 located at the connection between the orbiting scroll 3 and the crankshaft 9 has an intermediate pressure chamber 25, which will be described later, forming a first rear chamber on the outer peripheral side of the rear surface of the orbiting scroll 3. A second back chamber is formed in the center of the back surface of the orbiting scroll, and a pressure substantially equal to the discharge pressure acts on the oil chamber 20 to press the orbiting scroll 3 against the fixed scroll 2 . That is,
Acts as part of the force that maintains the axial seal between the orbiting and fixed scrolls. The oil led to the oil chamber 20 is transferred to the crank portion 9b of the crankshaft 9.
The sliding bearing 8 of the orbiting scroll 3 and the crank part 9b pass through the oil supply groove 21 provided in the axial direction on the outer peripheral surface of
and lubricate. The oil that has lubricated the slide bearing 8 passes through an annular groove 23 provided at the connection between the crank part 9b of the crankshaft 9 and the balance weight 22, and lubricates the thrust bearing 24 integrally formed at the bottom of the slide bearing 8, and then lubricates the thrust bearing 24 integrally formed at the bottom of the slide bearing 8. 10 and the orbiting scroll 3 is discharged into an intermediate pressure chamber 25 (first back chamber).

As shown in FIG. 2, this intermediate pressure chamber 25 is formed by a small hole 32 provided in the end plate 5 of the orbiting scroll, which is formed between the scrolls 2 and 3 by the meshing of the scrolls 2 and 3. Communicates with a closed space.

To supply oil to the upper plain bearing 11 that supports the shaft portion 9a of the crankshaft 9, the oil that has gone up in the eccentric oil supply path 19 is passed through the oil supply hole 26 that communicates with the eccentric oil supply path 19 and the oil supply hole 26 that communicates with this and is connected to the shaft portion 9.
This is done by supplying oil to the oil supply groove 27 provided in the axial direction on the outer circumferential surface of a. The oil that has lubricated the slide bearing 11 flows through the annular groove 28 provided at the connection between the shaft portion 9a and the balance weight 22 into the thrust bearing 29 integrally formed on the top of the slide bearing 11, and then lubricates the thrust bearing 29. It is discharged into the intermediate pressure chamber 25. A portion of the oil supplied to the upper sliding bearing 11 from the oil supply hole 26 flows from the lower part of the sliding bearing 11 to an oil drain chamber 30 defined by the shaft 9a, the frame 10, the sliding bearing 11, and the bearing 12. After the oil is discharged from the housing 1 through the oil drain hole 31 provided in the frame 10,
discharged inside.

The oil discharged into the intermediate pressure chamber 25 mentioned above passes through the pores 32 provided in the orbiting scroll 3 and is discharged into the closed space between the scrolls 2 and 3 during compression. Therefore, the pressure in the intermediate pressure chamber 25 becomes an intermediate pressure between the discharge pressure and the suction pressure. The pressure within this intermediate pressure chamber 25 provides part of the force that presses the orbiting scroll against the fixed scroll and maintains the axial seal between both scrolls.

Oil is supplied to the lower sliding bearing 12 that supports the shaft portion 9a of the crankshaft 9 by using oil sucked up by the centrifugal pump action of the eccentric oil supply path 19.
This is done by supplying oil to the oil supply hole 33 communicating with the eccentric oil supply path 19 and the oil supply groove 34 provided in the axial direction through the oil supply hole 33 on the outer peripheral surface of the shaft portion 9a. The oil that lubricates this sliding bearing 12 is
A portion is discharged into the housing 1 from the upper end of the slide bearing 12 through the oil drain chamber 30 and the oil drain hole 31, and the other portion is discharged into the housing 1 from the lower end of the slide bearing 12.

Lubricating the above-mentioned upper sliding bearing 11 and the sliding bearing 8 of the orbiting scroll 3 is performed by the differential pressure between the discharge pressure and the intermediate pressure and the centrifugal pump action of the eccentric oiling passage 19, whereas The bearing 12 is supplied with oil only by the action of the centrifugal pump in the oil supply passages 19 and 33. That is, discharge pressure is acting on the oil surface of the oil reservoir at the bottom of the housing, and on the other hand, the oil chamber 20 above the crank pin 9b in the boss on the back of the orbiting scroll is connected to the slide bearing 8 and the thrust bearing 24.
It is connected to the intermediate pressure chamber 25 through a large flow resistance provided by the oil reservoir, and also communicates with the oil reservoir through an oil supply path 19 having a small flow resistance. Therefore, the differential pressure between the discharge pressure acting on the oil reservoir and the intermediate pressure within the intermediate pressure chamber 25 acts as an oil supply force to the bearing 8. Upper bearing 11 of crankshaft 9
The same applies to On the other hand, lower bearing 1
Since the differential pressure mentioned above does not act on 2, oil supply to it is carried out only by the action of the centrifugal pump. Although the centrifugal pump action of the oil supply path 19 also adds to the oil supply force to the bearing 8, this centrifugal pump action is small;
Moreover, since there is a pressure loss due to the oil head from the oil reservoir to the oil chamber 20, the pressure within the oil chamber (second rear chamber) 20 becomes substantially equal to the discharge gas pressure.

As described above, since this embodiment has the above configuration, a discharge pressure acts inside the closed container (housing) 1, and this discharge pressure is applied to the oil reservoir in the housing 1 and the oil supply path 19 in the crankshaft. A second section provided on the back side of the orbiting scroll at the connection part between the orbiting scroll and the crankshaft
It acts on the oil chamber 20 which is the rear chamber of the engine. When the discharge pressure fluctuates, the pressure in this portion changes in proportion to the variation in the discharge pressure.

On the other hand, the above-mentioned intermediate pressure acts on the first back chamber (intermediate pressure chamber) 25 provided outside the second back chamber 20, and this intermediate pressure does not depend on the discharge pressure, but is dependent on the suction pressure. Changes according to fluctuations.

As a result, the axial pressing force applied to the orbiting scroll changes in accordance with the change in the force that attempts to separate both scrolls from each other caused by fluctuations in discharge pressure and fluctuations in suction pressure, respectively. It is possible to maintain a stable required axial pressing force even when the pressure changes.

This matter will be explained in detail below. A scroll compressor takes suction gas into a closed space (compression chamber) formed between a fixed scroll and an orbiting scroll, and compresses it by reducing the volume of the compression chamber that moves toward the center as the orbiting scroll rotates. However, at the end of this compression stroke, the compression chamber communicates with the discharge port in the center of the fixed scroll, thereby discharging compressed gas. Therefore, the pressure inside the compression chamber during the compression stroke depends only on the suction pressure; the higher the suction pressure, the higher the pressure; it does not depend on the discharge pressure (external pressure acting on the discharge port).
On the other hand, the pressure in the compression chamber during the discharge stroke after communicating with the discharge port is equal to the discharge pressure. The force that tries to pull apart both the fixed and orbiting scrolls in the axial direction is due to the fact that the suction gas before being taken into the compression chamber, the gas in the compression chamber during the compression stroke, and the gas in the compression chamber during the discharge stroke are applied to the end plate of the orbiting scroll. It is the sum of the forces pushing the area of action of each gas. As described above, among these forces, the first two depend only on the suction pressure, and the latter depend only on the discharge pressure.

In this embodiment, the pressing force that pushes the orbiting scroll in the axial direction against the separating force of both scrolls as described above is communicated with the compression chamber during the compression stroke, so that the suction pressure and the discharge pressure are The respective pressures of the first back chamber, on which an intermediate pressure acts, and the second back chamber, on which discharge pressure acts by communicating with an oil reservoir in the housing that receives discharge pressure, are applied to the back surface of the orbiting scroll end plate. It is the sum of the forces pushing in the direction. As a result, the above-mentioned excellent effects regarding the pressing force can be obtained.

The effects will be described below, taking as an example the case where the scroll compressor of this embodiment is used as a refrigerant compressor of an air conditioner. In general, the suction pressure and discharge pressure change depending on the operating conditions of the air conditioner. For example, during a transient period when the compressor reaches a steady state of operation after startup, the discharge pressure is lower than its steady state value and the suction pressure is higher than its steady state value. For example, these pressures also change depending on the air conditioning load. Such changes in suction and discharge pressures generally occur in opposite directions (i.e.
When the discharge pressure increases, the suction pressure decreases, and conversely,
When the discharge pressure decreases, the suction pressure increases). As a result, even if the suction pressure and the discharge pressure change, the above-mentioned total separation force remains approximately constant.

By the way, since the above-mentioned intermediate pressure in the first back chamber is the pressure led from the compression chamber during the compression stroke, when the suction pressure increases, the pressure in the first back chamber increases, and therefore, The pressing force exerted on the orbiting scroll by the first back chamber increases. On the other hand, since the discharge pressure decreases at this time, the pressing force exerted by the second rear chamber on which this discharge pressure acts becomes smaller.
As a result, the overall pressing force, which is the sum of the pressing forces from these two rear chambers, remains at an approximately constant appropriate value commensurate with the aforementioned approximately constant pulling force, even when the suction pressure increases and the discharge pressure decreases. become.
Conversely, even when the suction pressure decreases and the discharge pressure increases, the overall pressing force remains at a generally constant appropriate value commensurate with the pulling force for the same reason.

If, instead of using the above-mentioned configuration for applying pressing force according to the present invention, it is attempted to obtain pressing force only from the back chamber where intermediate pressure acts, it is necessary to obtain appropriate pressing force when the suction pressure is high. If the suction pressure is designed to be low, the pressing force will be insufficient, and if the suction pressure is low, the pressing force will be insufficient, and if the suction pressure is low, the pressing force will be excessive. This has the disadvantage that a stable and appropriate pressing force cannot be obtained.

Also, if you try to obtain pressing force only from the back chamber where the discharge pressure acts, if you design it so that the appropriate pressing force is obtained when the discharge pressure is high, then when the discharge pressure becomes low, the pressing force will be increased. On the other hand, if the design is designed to provide an appropriate pressing force when the discharge pressure is low, there is a drawback that an excessive pressing force will occur when the discharge pressure becomes high.

In the present invention, since the pressing force is obtained by the pressure of the two rear chambers, there is an excellent effect that a generally constant, stable and appropriate pressing force can be obtained even if the discharge pressure or suction pressure changes.

[Effects of the Invention] According to the present invention, the first pressure is maintained at an intermediate pressure between the suction pressure and the discharge pressure on the back surface of the orbiting scroll.
and a second back chamber maintained at a pressure substantially equal to the discharge pressure are provided on the outer circumferential side and in the center, respectively, thereby obtaining an axial pressing force of the orbiting scroll against the fixed scroll. This has the effect that the orbiting scroll can be appropriately and stably pressed against the fixed scroll not only in response to fluctuations in suction pressure but also in discharge pressure.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a scroll compressor that is an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view showing an enlarged crankshaft portion of the same embodiment, and Fig. 3 is an oil supply groove in the same embodiment. FIG. 3 is a plan view of the crankshaft. DESCRIPTION OF SYMBOLS 1... Housing, 2... Fixed scroll, 3... Orbiting scroll, 4, 5... End plate, 6, 7... Wrap,
8...Sliding bearing, 9...Crankshaft, 9a...
Shaft portion of crankshaft 9, 9b... Crank portion of crankshaft, 11, 12... Sliding bearing, 19... Eccentric oil supply path, 21, 27, 34... Oil supply groove, 31... Oil drain hole.

Claims (1)

[Scope of Claims] 1. A fixed scroll having a lap that stands upright on an end plate with a discharge port open in the center, and an orbiting scroll that has a lap that stands upright on an end plate and is combined with the fixed scroll so that the laps mesh with each other. , a crankshaft connected to the opposite lap side of the end plate of the orbiting scroll via a bearing, a bearing attached to the frame and rotatably supporting the crankshaft, an anti-rotation member for preventing rotation of the orbiting scroll, and the crank. Equipped with an electric motor that rotates the shaft and a housing that houses all of the above elements, the discharged gas from the discharge port in the center of the end plate of the fixed scroll is discharged into the housing and then flows out of the housing. However, in a scroll compressor configured such that the discharge gas pressure acts on the oil level of the oil reservoir in the housing, a first rear chamber defined on the outer circumferential side is located on the opposite wrap side of the end plate of the orbiting scroll. and a second back chamber defined in the center, and the first back chamber is in communication with the closed space in the middle of compression formed between the fixed and rotating scrolls, thereby adjusting the suction gas pressure. the second back chamber is maintained at a pressure substantially equal to the discharge gas pressure by being in communication with the oil reservoir; A scroll compressor characterized in that the pressing force of the orbiting scroll against the fixed scroll is obtained by the pressure in the back chamber of the scroll compressor. 2. Claim 1, characterized in that a connection hole is provided in the end plate of the orbiting scroll to communicate the closed space in the middle of compression formed between the two scrolls and the first back chamber. Scroll compressor as described. 3. The scroll compressor according to claim 1 or 2, wherein the second back chamber is provided at a connecting portion between the orbiting scroll and the crankshaft.