JPH0549830B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scroll compressor that compresses air or refrigerant gas.

First, the basic configuration and operating principle of a scroll compressor will be explained with reference to FIGS. 1 and 2.

The scroll compressor includes a fixed scroll member 1 formed by vertically forming a spiral wrap 1b formed of an involute curve or a curve approximating the involute curve on a disc-shaped end plate 1a, and the fixed scroll member 1.
An orbiting scroll member 2 consisting of an end plate 2a and a lap 2b having the same shape as the scroll member 2 is engaged with each other with the laps 1b and 2b facing inward, and an Oldham ring 3 that prevents the apparent rotation of the orbiting scroll member 2 is attached to the fixed scroll member 1. It is provided between the stationary part (frame) fixed to the orbiting scroll member 2 and the orbiting scroll member 2.

In such a configuration, when the center Om of the orbiting scroll member 2 rotates clockwise around the center O _s of the fixed scroll member 1, both mirror plates 1
The closed spaces 5a, 5b formed between the scroll members 1b, 2a and the wraps 1b, 2b and located at the ends of the wraps 1b, 2b expand in volume while moving toward the center of the scroll members 1, 2. is gradually shrinking.

Therefore, if the port 1d provided at the end of the fixed scroll member 1 is used as a discharge hole and the port 1c is used as a suction hole, and the orbiting scroll member 2 is rotated clockwise by the crankshaft 4, this device can be operated. Works as a compressor.

When this device is in operation, the force that tries to separate the fixed scroll member 1 and the orbiting scroll member 2 is applied to the closed spaces 5a, 5b, 5c, 5d.
The fluid pressure that exists inside acts on both scroll members 1 and 2, and therefore, if this continues, both scroll members 1 and 2 will become separated and normal compression action will no longer be possible.

Therefore, a back chamber is formed between the frame and the mirror plate side of the orbiting scroll member 2 opposite to the lap, and gas pressure or spring pressure is applied to the opposite side of the orbiting scroll member 2 to reduce the force of pulling it apart. A large pressing force is applied to the orbiting scroll member 2 to bring both scroll members 1 and 2 into close contact with each other, and the amount of movement of the orbiting scroll member 2 in the opposite direction from the lap is regulated by a thrust bearing.

A rear chamber of the end plate of the orbiting scroll member 2 is used as a back pressure chamber, and a small hole is provided in the end plate of the orbiting scroll member 2 to communicate between the back pressure chamber and each of the sealed spaces forming a pair of intermediate pressures during compression, Applying a pressing force larger than the pulling force to the orbiting scroll member 2
For example, JP-A-55-
Publication No. 148994, Japanese Unexamined Patent Publication No. 55-107093, Japanese Unexamined Patent Publication No. 1987-107093
It is disclosed in Publication No. 55-46046, etc.

In such a scroll compressor, the closed spaces 5a, 5 formed by both scroll wraps are
After completing the suction accompanying the rotating movement, the closed spaces 5a and 5b move toward the center and communicate with the discharge hole 1d provided in the center of the fixed scroll member 1.
Regardless of the discharge pressure, the pressure always follows a constant pressure history due to the suction pressure and changes in the volumes of the sealed spaces 5a and 5b. That is, the volume of the sealed space at the completion of inhalation is V _s , the volume of the sealed space during the compression process is V _i ,
Assuming that the suction pressure is P _s and the compression process is a polytropic change, the pressure P _i of the compression process is expressed by the following equation.

P _i = P _s [V _s /V _i ] ^nwhere , n: polytropic index Therefore, if the changes in the volume and pressure of the closed space during the compression process are shown in Figure 3, if the discharge pressure P _d is too high A change of 1-2-2'-3' is made, and if the discharge pressure P _d is too low, a change of 1-2-2''-3'' is made.

Therefore, compared to an ideal compression process, if the discharge pressure is too high, the area surrounded by 2-2'-4' will be lost work, and if the discharge pressure is too low, the area surrounded by 4''-2-2'' will be lost. The part surrounded by is the lost work,
This causes a decrease in compressor efficiency.

Even when there is no difference between the suction pressure and the discharge pressure, such as during startup, a 1-2-2-3 compression process is followed and the power required for the 1-2-2 change is consumed even though the pressure does not increase. Particularly when used as a compressor for refrigeration and air conditioning, when the balance pressure at startup is high, a large startup torque is required and the capacity of the drive motor needs to be increased.

In addition, when used as a compressor for refrigeration and air conditioning, and when liquid refrigerant is sucked into a closed space, the liquid refrigerant is compressed until the closed space communicates with the discharge hole.
There are various problems such as an abnormally high pressure in the sealed space, an increase in driving torque, and an increase in bearing load, which may cause damage to the shaft or bearing.

Furthermore, in a scroll compressor in which a pair of small holes are provided in the end plate of the orbiting scroll member to apply back pressure to the sealed back pressure chamber as described above to prevent separation, the pressure in the closed space is As the pressure increases, the pressure within the back pressure chamber also increases accordingly, resulting in a problem in that the pressing force of the orbiting scroll member against the fixed scroll member becomes excessive.

In addition, in a rotary compressor, two compression chambers are provided consecutively in the direction of rotation, and these compression chambers are bypassed by the action of a check valve depending on the pressure on the discharge side, and in a screw compressor, one A technique for preventing overcompression by providing a plurality of bypass holes in the compression chamber, selecting the bypass hole according to the pressure on the discharge side, and bypassing it by the function of a check valve is known, for example, from Japanese Patent Application Laid-Open No. 1972- As disclosed in the 2015 publication, this type of compressor does not have the symmetrically paired compression chambers that are unique to scroll compressors, so there is no problem of having to balance the compression chambers. Further, the problem of having to maintain an appropriate pressing force of the orbiting scroll member against the fixed scroll member does not occur.

The present invention was invented in view of the above problems, and it reduces the power loss that occurs when the pressure ratio during operation is smaller than the ideal pressure ratio determined by the volume ratio, and provides high performance regardless of the pressure ratio. get. Also,
To reduce the starting torque required at startup. Furthermore,
To prevent abnormally high drive torque and bearing load from occurring during liquid compression.

An object of the present invention is to provide a scroll compressor having the functions described below.

To achieve the above object, a scroll compressor according to the present invention includes a fixed scroll member formed by standing a spiral wrap upright on an end plate having a discharge hole opening into a discharge chamber at a central position, and a fixed scroll member on the end plate. The spiral wrap is engaged with an orbiting scroll member formed by standing up a spiral wrap of substantially the same shape, and a suction chamber is formed on the outer periphery of the spiral wrap that is engaged with both the scroll members, and means for preventing rotation of the scroll member; orbiting scroll member driving means for causing the orbiting scroll member to orbit without rotating; and a back chamber formed on the side of the mirror plate opposite to the lap of the orbiting scroll member. and a pair of sealed spaces formed symmetrically between a spiral wrap of the orbiting scroll member and a spiral wrap of the fixed scroll member during the orbiting movement of the orbiting scroll member, the volume of which is successively reduced. In the scroll compressor, the scroll compressor is moved toward the discharge hole so that the suction gas from the suction chamber is discharged as compressed gas from the discharge hole into the discharge chamber or the discharge pipe,
A discharge hole is provided in the end plate of the fixed scroll member to connect each of the sealed spaces forming the pair before the sealed space communicates with the discharge hole with a discharge chamber or a discharge pipe, and a discharge hole or a discharge hole is provided in each of the discharge holes. In addition to providing a check valve that communicates only in the direction to the piping, the back chamber is made into a sealed back pressure chamber, and the back pressure chamber is connected to each of the pair of sealed spaces having an intermediate pressure during compression. A small hole is provided in the end plate of the orbiting scroll member between the discharge hole and the discharge hole.

In the scroll compressor of the present invention having the above-mentioned characteristics, if the pressure in the closed space during the compression is higher than the pressure in the discharge chamber or the discharge pipe, before the closed space communicates with the discharge hole. It is possible to send fluid to the discharge chamber or discharge piping to prevent the pressure in the closed space from rising abnormally. Since a pair of small holes are located between each discharge hole provided in the end plate of the fixed scroll member and the discharge port, when the fluid is sent through the discharge hole before the closed space communicates with the discharge port, it is necessary to The intermediate pressure level in the back pressure chamber decreases accordingly, and the axial pressing force of the orbiting scroll against the fixed scroll also decreases accordingly, so that the pressing force is properly maintained without becoming excessive.

An embodiment in which the present invention is applied to a hermetic scroll compressor will be described below with reference to FIG.

The airtight container 6 is made up of three parts 6a, 6b, and 6c and houses the following equipment. Both scroll members 1 and 2 are engaged with each other with their laps 1b and 2b facing inward. Fixed scroll member 1 is attached to frame 9 with several bolts (not shown). The frame 9 is attached to the airtight container 6,
It is fixed by press-fitting, welding, etc. The crankshaft 4 is rotatably supported by a bearing 13 attached to the frame 9, and one end is supported by a bearing in the boss portion of the orbiting scroll member. The rotation prevention member 3 is connected to the back surface of the orbiting scroll member 2 and the frame 9.
is established between. Orbiting scroll member 2
On the back side, the end plate 2a of the orbiting scroll member, the frame 9, the crankshaft 4, and the bearings 12, 13 are shown.
A back pressure chamber 14 is provided, and communicates with the closed space formed by both laps 1b and 2b through a small hole 2d provided in the orbiting scroll end plate 2a. Thereby, the pressure in the back pressure chamber 14 is maintained at an intermediate pressure between the suction pressure and the discharge pressure, and the axial pressing force necessary to bring the orbiting scroll member 2 into close contact with the fixed scroll member 1 is obtained. The pair of small holes 2d are provided in the end plate 2a of the orbiting scroll member 2 between the discharge hole 19 described later and the discharge hole 1d.

The stator 7a of the motor 7 is attached to the inner wall surface of the closed container 6, and the rotor 7b is attached to the crankshaft 4.
installed on.

The suction hole 1c is provided on the outer periphery of the fixed scroll member 1 and connects the suction pipe 10. Further, the discharge hole 1d is provided at the center of the fixed scroll member 1 and opens into the upper chamber (discharge chamber) of the closed container 6. The discharge pipe 11 is attached to the closed container 6. Lubricating oil 15 is stored in the lower part of the closed container 6, and is supplied to each sliding portion through an oil hole (not shown) provided in the crankshaft 4. The closed container 6 is divided into an upper discharge chamber 16 and a lower motor chamber 17 by the fixed scroll member 1 or the frame 9, and a communication passage 18 connecting these is provided in the fixed scroll member 1 and the frame 9.

The working gas is sucked in through the suction hole 1c, compressed as the crankshaft 4 rotates, becomes a high-temperature, high-pressure gas, and is discharged into the discharge chamber 16 through the discharge hole 1d, then sent to the motor chamber 17, passing around the motor. , and is sent from the discharge pipe 11 to external equipment.

Both laps 1 are attached to the end plate 1a of the fixed scroll.
A discharge hole 1 that connects a closed space during compression formed by b and 2b and a discharge chamber 16 in the upper part of the closed container.
9 is provided, and the outlet wall to the discharge chamber 16 is provided with a check valve 20 consisting of a reed valve 20a and a valve holder 20b. The discharge hole 19 has a symmetrical pressure in the two sealed spaces formed by both wraps.
One each is provided at a position that is not directly connected to either the suction chamber pressure or the discharge chamber pressure at a rotation angle position that is a predetermined rotation angle before the rotation angle of the orbiting scroll where the sealed space has a minimum volume. Of course, the same applies even when a plurality of them are provided.

In a hermetic scroll compressor with such a configuration, when the pressure in the hermetic space becomes higher than the pressure in the discharge chamber, the check valve 20 opens and the gas in the hermetic space is sent out from the discharge hole 19 to the discharge chamber 16. This prevents unnecessary pressure build-up in the enclosed space. Also, if the pressure inside the closed space is lower than the pressure inside the discharge chamber,
Check valve 20 closes and prevents backflow of gas into the compression chamber.

5a and 6b and 6a and 6b show other embodiments of the check valve.

In FIG. 5, the check valve consists of a ball 21 and a frusto-conical valve seat 23a on the lower wall of the valve chamber 23. If the pressure in the closed space is higher than the pressure in the discharge chamber, the bulb 21
is pushed up and hits the stopper 22 in the shape of an occluded circle. The gas in the closed space is discharged from the bulb 2 through the exhaust hole 19'.
1 and around the stopper 22, and the discharge chamber 16
sent to. When the pressure in the discharge chamber 16 is higher than the pressure in the closed space during compression, the ball 21 comes into close contact with the seat 23a to prevent backflow.

In FIG. 6, the check valve has a valve seat 25a formed in the lower wall of the valve chamber 23 communicating with the discharge hole 19'', a truncated conical valve body 24 disposed in the valve chamber 23, and a spring 26. Reference numeral 22 indicates a stopper in the shape of a missing circle.The operation is similar to that shown in Fig. 5, and the operation becomes more reliable when a spring 24 is added. A similar effect can be obtained when a spring is added to what is shown.

In the check valves shown in Figures 5 and 6, since the valve is formed close to the wall of the closed space, the volume of the discharge hole is small, and efficiency decreases due to re-expansion and re-compression in this area. can be suppressed.

FIG. 7 shows an example of an open type compressor, in which a discharge pipe 31 and a discharge hole 32 are connected by a pipe 33, and a check valve 34 is provided in the middle.The other parts are shown in FIG. This is a sectional view taken in the same direction as in the conventional example, and its explanation will be omitted.

As explained above, according to the present invention, a discharge hole is provided that connects a previously sealed space that communicates with the discharge hole and a discharge chamber or a discharge pipe, a check valve is provided in the discharge hole, and the discharge hole in the sealed space is If the pressure is higher than the discharge pressure, pumping out the compressed fluid in the closed space;
Prevents the pressure in the closed space from rising above the pressure in the discharge chamber, reduces loss of movement, and always achieves high performance efficiency. The starting torque at startup is also reduced,
Furthermore, during liquid compression, etc., it is possible to prevent the pressure in the sealed space from increasing abnormally, and prevent the driving torque and bearing load from becoming abnormally high. When the fluid is sent out through the discharge hole, the level of intermediate pressure in the back pressure chamber decreases accordingly,
Since the axial pressing force of the orbiting scroll against the fixed scroll is correspondingly reduced, the pressing force can be properly maintained without becoming excessive.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a conventional scroll compressor.
Fig. 2 is a cross-sectional view taken along the - line in Fig. 1, Fig. 3 is a diagram showing the relationship between the volume and pressure of the compression chamber, and Fig. 4 is a longitudinal cross-section of a scroll compressor showing an embodiment of the present invention. The plan view, FIGS. 5 and 6 are enlarged views showing other embodiments of the check valve portion, and FIG. A shows a sectional view, and FIG. B shows a plan view. FIG. 7 is a longitudinal sectional view of a scroll compressor showing still another embodiment. 1...Fixed scroll member, 1a...End plate, 1b...
Wrap, 2... Orbiting scroll member, 2a... End plate,
2b...Wrap, 19, 19', 19''...Drain hole, 2
0... Reed valve (check valve), 21, 24... Valve body, 2
2... Stopper, 23, 25... Valve chamber, 23a, 25
a...Valve seat, 26...Spring, 31...Discharge piping,
32...Discharge hole, 33...Piping, 34...Check valve.

Claims (1)

[Scope of Claims] 1. A fixed scroll member formed by standing a spiral wrap upright on an end plate having a discharge hole opening into a discharge chamber in the center, and a spiral wrap of the fixed scroll member on the end plate, substantially Means for engaging an orbiting scroll member formed by standing upright spiral wraps of the same shape, forming a suction chamber in the outer periphery of the spiral wrap that is engaged with both scroll members, and preventing rotation of the orbiting scroll member. , an orbiting scroll member driving means for causing the orbiting scroll member to orbit without rotating; and a back chamber formed on a mirror plate surface side opposite to the wrap of the orbiting scroll member, the orbiting scroll member During the orbiting movement of the orbiting scroll member, a pair of sealed spaces formed symmetrically between the spiral wrap of the orbiting scroll member and the spiral wrap of the fixed scroll member is moved toward the discharge hole while gradually decreasing the volume. In the scroll compressor, the suction gas from the suction chamber is discharged as compressed gas from the discharge hole to the discharge chamber or the discharge pipe, wherein the end plate of the fixed scroll member has a state in which the closed space is in communication with the discharge hole. A discharge hole is provided that connects each of the pair of sealed spaces to the discharge chamber or the discharge pipe, and each of the discharge holes is provided with a check valve that communicates only in the direction to the discharge chamber or the discharge pipe. No sealed back pressure chamber,
A small hole is provided in the end plate of the orbiting scroll member between the discharge hole and the discharge hole, which communicates the back pressure chamber with each of the pair of closed spaces having an intermediate pressure during compression. scroll compressor. 2. The scroll compressor according to claim 1, wherein the check valve is a reed valve provided on the mirror plate surface of the fixed scroll member at a portion where the discharge hole opens into the discharge chamber. 3. Claim 1, wherein the check valve comprises a valve seat formed in the discharge hole, and a spherical or conical valve body disposed in the valve seat. Scroll compressor as described. 4. The scroll compressor according to claim 1, wherein the check valve is provided in a discharge pipe connected to the discharge hole.