JPH03134285A - Sealed type variable speed scroll compressor - Google Patents

Abstract

PURPOSE:To provide a small-sized compressor which is suitable for high speed operation or low speed operation by means of inverter driving by setting times at 2 - 2.5 and installing a check valve mechanism at a discharge port to make a back pressure opening a rationalized mechanism. CONSTITUTION:Lap times of a fixed scroll member 5 and a swivel scroll member 6 are set at approximately 2 - 2.5, the fixed scroll member 5 is provided with a check valve mechanism 4 on the upper part of a discharge port 10 in the center part of an end plate 5a so that the motor part may be variable speed-operated with an inverter 30. Besides, in the end plate of the swivel scroll member 6, a back pressure opening which communicates a compression chamber with a back pressure chamber 20 installed on the rear surface of the end plate is opened inwardly from the end edge part of the lap by one turn, and the innermost chamber in the lap center part formed out of both scroll members 5, 6 and the back pressure opening are so constituted as to have such a positional relation as their communication may be interrupted all the time.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a hermetic scroll compressor used as a refrigerant compressor for, for example, refrigeration and air conditioning. The present invention relates to a suitable hermetic scroll compressor.

[Prior art] In the conventional scroll compressor, Japanese Patent Application Laid-Open No. 59-11909
As described in Publication No. 1, the structure is such that oil drain passages for returning oil from the outer periphery of the end plate of the orbiting scroll to the compression chamber are provided radially within the end plate of the orbiting scroll. In addition, the scroll wrap shape of scroll compressors for air conditioning applications was developed in Japanese Patent Application Laid-open No. 6
As described in Japanese Patent No. 2-13790, there is a structure in which the number of turns of the scroll wrap is around three and a discharge valve (check valve) is attached to the discharge port in the center of the fixed scroll member.

[Problems to be Solved by the Invention] Both of the above-mentioned prior art relate to so-called constant-speed scroll compressors in which the rotational speed of the compressor is constant. By the way, when the compressor is driven by an inverter for condition control that can change the refrigerating capacity and the rotational speed is changed from a low speed to a high speed range, the following problem occurs.

(1) Increase the speed of the compressor (for example, the rotation speed is 900 rpm)
), the large number of wraps causes overcompression to occur, resulting in a large compressor power loss. (
2) Since the above-mentioned oil drainage passage is set to be large, when the rotation speed becomes low, the suction gas flows into the back pressure chamber (provided on the opposite side of the orbiting scroll member to the fixed scroll member,
The oil in the chamber (which has a pressure effect that presses the orbiting scroll member against the fixed scroll member) makes it easier to receive heat.
As a result, the degree of internal heating of the suction gas temperature within the compressor (suction chamber) increases, resulting in a decrease in volumetric efficiency in the low rotational speed range. As described above, the conventional scroll compressor described above has problems in terms of performance when attempting to operate over a wide range from a low speed range to a high speed range.

An object of the present invention is to solve the above-mentioned problems, to be suitable for speeding up or slowing down a scroll compressor by inverter drive, and to make it possible to downsize the compressor.

[Means for Solving the Problems] The hermetic scroll compressor of the present invention is driven at variable speed by an inverter, and the number of wraps N of both the fixed and orbiting scroll members is approximately 2 to 2.5. , a discharge valve (check valve) mechanism 3 is provided above the discharge port in the center of the end plate of the fixed scroll member, and an orbiting scroll is provided to communicate the back pressure chamber and compression chamber located on the back side of the end plate of the orbiting scroll member. The position of the back pressure hole provided in the end plate is set one turn inward from the end of the wrap, and the back pressure hole is located in the innermost chamber formed by the wraps of both scroll members (the compression hole near the discharge port). This is to set the smallest number N of scroll wraps such that the positional relationship does not always communicate with the working chamber.

In order to reduce loss caused by oil in the back pressure chamber formed on the back side of the end plate of the orbiting scroll member, an oil drain hole is provided to return oil accumulated in the side space of the outer periphery of the end plate of the orbiting scroll member to the compression chamber. is provided in the end plate, and the stroke volume V of the compressor, such as the sum S of the area St of the oil drain hole and the area Sb of the back pressure hole,
The diameters of the oil drain hole and the back pressure hole are set so that the dimensionless area ratio S=(St+Sb)/Vtk3, which is the ratio to h, is equalized from 00OO5 to around 0.007.

In addition, in response to higher speed compressors, the material of the orbiting scroll member is made of a light alloy (for example, Aluminum 11 alloy), and the starting end of the wrap is made with a relatively large radius to improve the wrap strength. It has a circular arc shape.

Also, the lap height.

and the wrap thickness t (h5/l) is set to about 6.0 or less.

[Function] The number of wraps is 2 to 2.5, which is smaller than the conventional one, so there is no overcompression in the high-speed range, and a discharge valve (check valve) is installed at the discharge port in the center of the fixed scroll member. There is little leakage even in the low speed range, so the capacity control range can be expanded during the operating range. By optimizing the configuration of the back pressure hole and the oil drain hole, heating of the intake gas by oil is reduced and the volumetric efficiency is improved.

Having a three-arc shape at the starting end of the wrap contributes to improving the wrap strength.

[Embodiment] FIG. 1 is a longitudinal sectional view showing the overall structure of an inverter-driven hermetic variable speed scroll compressor according to an embodiment of the present invention. The drive motor of this compressor is operated at variable speed by an inverter 300, and both are electrically connected by a power cable 301. The entire compressor is housed in a closed container 1. FIG. 2 is a plan view of the fixed scroll member 5, and FIGS. 3 and 4 are a plan view and a vertical sectional view of the orbiting scroll member 6, respectively.

FIG. 5 is a longitudinal sectional view of the vicinity of the center of both the fixed and orbiting scroll members.

In the compressor section, a fixed scroll member 5 and an orbiting scroll member 6 are engaged with each other, and a compression chamber (sealed space) 7 is formed between them. The fixed scroll member 5 is made of cast iron material (hereinafter referred to as FC material) that has relatively excellent self-lubricating properties, and includes a disk-shaped end plate 5a and an involute curve or a curve similar to this that stands upright thereon. Wrap 5b formed on
It has a pointed shape, and has a discharge port 1o at its center and an intake port 1G at its outer periphery.

The orbiting scroll member 6 includes a disc-shaped end plate 6a, a wrap 6b standing upright on the end plate and formed in the same shape as the wrap of the fixed scroll, and a boss 6c formed on the opposite wrap surface of the end plate.
It is pointed. The material of the orbiting scroll member 6 is a light alloy such as an aluminum alloy in order to realize a high speed compressor. This is to prevent the centrifugal force acting on the orbiting scroll from increasing as the speed increases, and this force from increasing the load on the orbiting bearing (excessive bearing surface pressure). In addition, by using the orbiting scroll member made of aluminum alloy, an effect can be obtained in that the end plate behavior (minimal displacement in the axial direction) of the orbiting scroll member is stabilized as the centrifugal force is reduced.

The frame 11 fixed to the closed container 1 has a bearing part 31, 33 in the center, and a rotating shaft (main shaft) 14 is attached to this bearing part.
is supported, and the eccentric shaft portion 14a at the tip of the rotating shaft is inserted into a swing bearing 32 fitted in the boss 6C so as to be able to swing.

A fixed scroll member 5 is fixed to the frame 11 with a plurality of bolts, and the orbiting scroll member 6 is made of Oldham aluminum alloy, which is made of aluminum alloy and subjected to appropriate surface treatment (Kanizen plating treatment, etc.) to ensure sliding properties between the aluminum members. The orbiting scroll member 6 is supported by the frame 11 via an Oldham mechanism 12 consisting of a ring and an Oldham key, and is arranged so as to perform an orbiting movement without rotating relative to the fixed scroll member 5.

The lubricating oil is stored as an oil reservoir 22 at the bottom of the closed container 1. The lower end of the main shaft 14 is immersed in the oil reservoir 22 at the bottom of the container 1, and the eccentric shaft portion 14a at the upper part of the main shaft is engaged with the orbiting scroll member 6 via an orbiting bearing 32. A central vertical hole 13 for supplying oil to each bearing portion is formed in the main shaft 14 from the lower end of the main shaft to the upper end surface of the main shaft. Reference numeral 15 denotes an oil lifting pipe that connects the lower end of the main shaft and the oil reservoir 22 at the bottom of the closed container 1. A balance weight 8 is formed in the lower part of the eccentric shaft part 14a to be integrally engaged with the main shaft 14 at a position above the main bearing 31 facing the orbiting scroll boss part 6c.

An electric motor shaft 14b to which a rotor 3b is fixed is integrally connected to the lower part of the rotating shaft 14, and the electric motor 3 is installed together with the stator 3a fixed to the container 1. A vertical suction pipe 17 is connected to the suction port 16 of the fixed scroll member 5 through the closed container 1 . The upper chamber 1a in which the discharge port 10 is open communicates with the upper motor chamber 1b via passages 18a and 18b. The upper motor chamber 1b communicates with the upper motor chamber IC via a passage 46 between the motor stator 3a and the side wall of the closed container 1.

Further, the upper motor chamber 1b has a discharge pipe 1 passing through the closed container 1.
It is connected to 9.

When the main shaft 14 is rotated by the electric motor section, the eccentric shaft section 14a causes the orbiting scroll member 6 to orbit (revolution) relative to the fixed scroll member 5, and the compression chamber formed between both scroll members 5 and 6 is As the volume of the gas is gradually reduced, the gas inhaled from the suction pipe 17 is compressed and discharged from the central discharge Jlo into the upper chamber la. Upper chamber 1
The gas discharged into the upper motor chamber 1b passes through the passages 18a and 18b, and a part of the gas passes through the passage 46 and enters the lower motor chamber IC, and finally the gas is discharged to the outside from the discharge pipe 19. . In FIG. 1, solid arrows indicate the flow direction of the refrigerant gas.

On the other hand, the dashed arrows in FIG. 1 indicate the direction of oil flow. This will be explained below. The lubricating oil is supplied to each bearing part by differential pressure lubricating by lubricating the L center hole. At the same time, the upper space of the eccentric shaft portion 14a (the bottom surface of the orbiting scroll boss portion 6c and the eccentric shaft portion 1
4a) through the swivel bearing part 32.
will be refueled. The oil supplied to each bearing portion enters a back pressure chamber 20 formed between the back side of the orbiting scroll end plate 6a and the frame 11. The oil flowing into the back pressure chamber 20 mixes with refrigerant gas and flows out into the compression chamber 7 through a back pressure hole 6d and an oil drain hole 6m provided in the orbiting scroll end plate 6a. On the other hand, the oil in the back pressure chamber 20 moves to the side space 11f of the adjacent orbiting scroll end plate, returns to the back pressure chamber again, enters the end plate sliding surfaces of both scroll members, and is then discharged to the suction chamber 5f. do. In this way, the oil in the back pressure chamber moves to the suction chamber 5f and eventually to the compression chamber 7. This oil is pressurized together with the gas, and eventually moves to the discharge chamber 1a above the fixed scroll member 5 and further to the motor chamber 1b. Refrigerant gas and oil are separated in this motor room, and the oil falls into an oil sump 22 at the bottom of the closed container 1, and is again supplied to each bearing and sliding part.

A discharge valve (check valve) mechanism 4 is attached to the upper part of the discharge port 10 of the fixed scroll m removal 5a, thereby ensuring operation in a high operating pressure ratio range and achieving the effect of reducing the compressor power.

As shown in FIG. 5, the discharge valve 4 is composed of a retainer 4a and a reed valve type thin plate 4b, which is the same as the valve 3.

4c is a bolt for fixing the valve to the fixed scroll end plate 5a.

In FIG. 2 showing the fixed scroll member 5, points A and L
The points are the starting points of the involute curves outside the wrap and the involute curves inside the wrap, respectively, while the Q point and the 8 point mark the end points of these involute curves, respectively. Each symbol A in FIG. 3 showing the orbiting scroll member
, L, and SbQ are also defined in the same way as above.

The number of lap turns (the number of turns of the involute curve part) N defined by the present invention is expressed by the following formula.

2π Here, λ2: Involute angle λ4 of point Q, which is the contact point of both the fixed and orbiting scroll wraps on the wrap outer curve when forming the maximum hermetic seal. Involute angle λλ of point A, which is the starting point of the outside curve of the wrap: Fixed at the inside curve of the lap when the maximum sealed space is formed.
Involute angle λr of 8 points that are the contact points of both orbiting scroll wraps = L point involute angle that is the starting point of the inside curve of the wrap The number of turns N of the wrap shown in Figures 2 and 3 is N'': 2
．． It is 3. Practically speaking, N=2.3 or so is optimal.

In this way, by reducing the number of wraps than before, the discharge bypass valve that bypasses gas from the compression chamber side to the discharge pressure side in the middle of the wrap, which is a conventional means to prevent overcompression, has been reduced. No structure may be required.

FIG. 6 shows the detailed structure of the wrap tip (starting end) 6e. Although this figure shows the wrap tip 6e of the orbiting scroll member 6, the same applies to the wrap tip 5e of the fixed scroll member 5. In FIG. 6, a is the basic circle radius of the involute curve, and 0° is its center. As shown in the figure, involume 1 to the starting point of the curve and A are smoothly connected by a concave arc curve LG centered on point C and a convex arc curve AG centered on point OR.

The radii of both arcuate curves are indicated by R1 and Ro, respectively.

The groove width D0 between the laps is set to be twice as large as R, and there is a linear relationship.

D,=2πa-t=2·R,...(3) Here, the wrap thickness is represented by t. On the other hand, the radius R0 is greatly related to the strength of the scroll wrap member, and as shown in FIG. 7, increasing the radius R0 increases the wrap strength (fatigue strength δ
, ) can be seen to improve dramatically. On the contrary,
Even if the radius R6 is increased, the number of wrap turns N is only slightly reduced, and the above-mentioned arcuate shape of the wrap tip functions effectively in terms of reliability. Note that the horizontal axis in Fig. 7 is Ra.
/a, that is, the ratio of the radius R0 to the basic circle radius a. In this embodiment, aluminum alloy is used as the material of the orbiting scroll member 6, and the arc radius ratio (R
0/a) is approximately 0.4.

Conventionally, the wrap tip 6 is extended to the intersection point F between the extension of the inner arcuate curve LG and the extension of the outer involute curve in FIG.
e exists, and the area Δ shown with diagonal lines in FIG.
FAG is a lap portion removed by changing the conventional scroll tooth shape to the circular arc shape of the embodiment of the present invention, and is the volume V of the innermost chamber 7c. This is an area where the number of people has increased by that amount.

The dead volume of this region is expressed as V. This dead volume V
The size of , even if the arc radius R is large, the total dead volume V. (As shown in FIG. 5, the volume Vdd of the innermost chamber 7c and the volume V of the discharge port 10.

(which can be expressed as the sum of Generally, when the dead volume is large, the power tends to increase under high pressure ratio operating conditions, but the arc shape of the wrap tip in this example has a slight effect on performance deterioration, and is rather effective in improving the wrap strength. is large.

Furthermore, since the involute curve starts at a mermaid rather than at point F, there is also the effect of reducing the number of wraps.

3 and 4, back pressure holes 6d (two) and oil drain hole 6m (one) are provided in the end plate 6a of the orbiting scroll member 6 along the scroll wrap side wall. The oil drain hole 6m communicates with the outer periphery of the orbiting scroll end plate through an oil drain path 6g. Note that 6f is an Oldham keyway. The two back pressure holes 6d are located at 8 points and Q, which are the terminal ends of the scroll wraps, respectively.
At a position one turn inward from the point position, the end plate 6
It is provided in a. Depending on the position of the back pressure hole, the pressure in the back pressure chamber 20 can be maintained appropriately and the oil draining action can be made smooth. On the other hand, the oil drain hole 6 rn is located at a position where the pressure is lower than the position of the back pressure hole 6 d, and the lap winding angle is at most Δλ=t/a (here, t thickness, a : base circle radius) is set at a position outward from the position of the back pressure hole 6d. here,
Both the back pressure hole 6d and the oil drain hole 6m have the function of an oil drain passage that moves oil accumulated in the back pressure chamber 20 to the compression chamber 7 side. In this embodiment, the passage area is optimized, and based on experimental results, the passage area S (which is expressed by the following equation (4)) is set as follows.

S = Sb + St (4) Here, Sb is the cross-sectional area that is the minimum constriction part of the back pressure hole 6d,
Sb is the cross-sectional area of the minimum constriction of the oil drain hole 6m. This is determined by the diameter 65 and dt dimensions of the chain hole opening into the fI normal compression chamber, as shown in FIGS. 3 and 4. As a method for optimizing this passage area, the stroke volume of the compressor (
Dimensionless oil drain area ratio S = (S t + S b) / V th' which is the ratio to the maximum sealed chamber volume) V ch
The diameters of the oil drain hole and the back pressure hole are set so that the value is around 0.005 to 0.007. S is practically 0.0
It has been experimentally determined that around 06 is optimal. This will be explained below.

Figure 8 shows the relationship between the dimensionless oil drain area ratio S and compressor performance (expressed as a change in total adiabatic efficiency). This figure shows the compressor motor drive frequency H, = 20tlz and H.

This is an experimental result when = 150Hz. In the conventional machine, the oil drain area ratio S* was around 0.009, and the structure of the compressor was suitable for operation in a high speed range. However, when trying to expand the capacity control range of the compressor,
Requires operation in low speed range. At this time, as shown in FIG.
The performance will be drastically reduced. This is due to the effect of the oil circulating in the compressor overheating the suction gas, as described above. In the present invention, in a scroll compressor with a wide range, in order to obtain the structure for optimizing the oil drainage area, the dimensionless oil drainage area ratio S11 is set as S'=0.005 to 0.007.
Set before and after. As a result, as shown in FIG. 8, the performance of the compressor can be maintained at high efficiency over a wide range even in the low speed range and the high speed range. If you set the value of S4 larger than this,
On the other hand, if the value of S″1 is set smaller than this, the pressing force from the orbiting scroll member 6 to the fixed scroll member 5 due to the pressure increase in the back pressure chamber 20 will be reduced in the high speed range. This causes negative effects in terms of performance, such as an increase in oil agitation loss due to the balance weight 8.

FIGS. 9 and 10 are a plan view and a longitudinal sectional view of the orbiting scroll member 6 showing other embodiments regarding proper setting of the oil drain path 6g. The oil drain passage 6g is characterized in that it is set to be inclined in the advance direction at 45 degrees with respect to the direction of the orbiting movement of the orbiting scroll member. Since the pressure fluctuation in the side space of the outer periphery of the armor plate 6a of the orbiting scroll member 6 has a large pressure value in the 45-degree advancing direction during the orbiting motion of the orbiting scroll member, in this embodiment, the pressure fluctuation is effectively suppressed. It can be kept small.

As a result, it is possible to further reduce hydraulic pressure fluctuations due to the presence of oil in the side space, and to reduce torque loss in this portion. This action and effect becomes more noticeable as the speed of the compressor increases.

Note that in each of the embodiments described above, the orbiting scroll member 6
An aluminum alloy (for example, AHS material) is used, the tooth height ratio (h,/t) is set to 6.0, and the radius R of the circular arc portion AG at the wrap starting end 6e.

An example is shown in which inn is set. The involute base circle radius a at this time is 2.38 mm.

According to the above compressor configuration, it is possible to optimize the number of turns of the scroll wrap and reduce loss due to oil. An example of the operation of the embodiment of the present invention is shown in FIGS. 11 and 12. 11th
As shown in the figure, in the embodiment of the present invention, the number of wraps is set smaller than that of the conventional machine, and the wrap specifications are adapted to high speeds, and a discharge valve mechanism 4 is provided in the center of the fixed scroll member. This reduces leakage between laps at low speeds. In this way, by skillfully combining the installation of the discharge valve 4 and the reduction in the number of wraps, it is possible to expand the operating range and the capacity control width. On the other hand, in order to increase speed, an aluminum alloy is used as the orbiting scroll member, which has the effect of reducing the load acting on the orbiting bearing to about 1/3 compared to the cast material of conventional machines.

At the same time, since the balance weight 8 is made smaller, the effect of reducing oil stirring loss within the back pressure chamber 20 can be obtained.

Furthermore, since the size of the oil drain passage described above is optimized, it is possible to eliminate adverse effects such as the heating effect of oil on the working gas.

In this way, the nine embodiments of the present invention successfully combine the above-mentioned configurations, and in a variable speed scroll compressor operated by an inverter, the number of scroll wraps is 2 to 2.5.
It has a wrap shape with a low number of windings in the front and rear, and in order to expand the operating range, a check valve mechanism part 4 is provided above the discharge port 10 of the fixed scroll member 5, and an aluminum alloy is used as the material of the orbiting scroll member 6. In addition, by forming the start end 3 of the wrap into an arc shape with a relatively large radius R6,
Achieving high speed and miniaturization of scroll compressors, high performance and
The configuration is suitable for a wide range scroll compressor with high reliability.

FIG. 13 is an explanatory diagram showing a comparison between the operating range of the conventional machine and the operating range of the present invention. Since the conventional inverter-driven compressor does not have the discharge valve mechanism 4, the operating range in the low rotational speed region is particularly narrow. On the other hand, in the present invention, since the discharge valve 4 is provided, the operating range in the low speed range and high speed range is expanded. This is due to the effect of the discharge valve 4, which reduces the amount of leakage in the low speed range, contributing to improved performance and, in turn, to an expanded operating range.

Although the embodiment in which the end plate of the orbiting scroll member is provided with back pressure holes and oil drain holes has been described, one feature of the present invention is also applicable to the end plate structure without intermediate pressure holes and the scroll wrap shape. Applicable. In other words, the internal pressure of the closed container is low, the number of wraps is in the range N = 2 to 2.5, and the rotation speed of the scroll compressor is controlled, which is equipped with a discharge valve (check valve) mechanism 3 at the upper part of the discharge port. It is possible to configure a low-pressure type variable speed scroll compressor that controls the air conditioner by controlling the air conditioner.

[Effects of the Invention] According to the present invention, a scroll compressor can be made faster and smaller, and the product cost can be reduced.
The scroll compressor can be made easy to use with a wide range of capacity control using inverter control, and can be operated over a wider range than conventional machines. can get.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a longitudinal sectional view showing the overall structure of a hermetic scroll compressor, FIG. 2 is a plan view of the fixed scroll member, and FIGS. 3 and 4 are the orbiting scroll members. 5 is a vertical sectional view near the center of the fixed/orbiting surface scroll member, FIG. 6 is a plan view showing the shape of the starting end (tip end) of the wrap, FIG. FIG. 8 is an explanatory view of the operation, FIGS. 9 and 10 are plan views and longitudinal sectional views of other orbiting scroll members, and FIGS. 11, 12, and 13.
The figure is an explanatory diagram of the action. 1... Airtight container 4... Discharge valve (check valve) mechanism 5... Fixed scroll member 6... Orbiting scroll member 8... Balance way 1-11... Frame 17... Suction Pipe 20...Back pressure chamber 6m...Drain hole 10...Discharge port 14...Main shaft 19...Discharge pipe 6d...Back pressure hole (1 other person) Figure (λI) (λms) Arc radius ratio Rc/a Figure Dimensionless oil drain area ratio Sea (Sb+Sf) ■thI/2 Figure Figure Kumoyumon Figure 0

Claims (1)

[Scope of Claims] 1. A scroll compressor section and an electric motor section are housed in a closed container and are connected to each other via a main rotating shaft supported by a frame fixed to the closed container, and the inside of the closed container is surrounded by a frame. In the scroll compressor section, a fixed scroll member and an orbiting scroll member are interlocked with each other with the wraps inside, with a spiral wrap standing upright on a disc-shaped end plate, and the orbiting scroll member is engaged with an eccentric shaft connected to the main rotating shaft, so that the orbiting scroll member can be rotated relative to the fixed scroll member without rotating on its own axis. A suction port is provided that opens at the end, gas is sucked in from the suction port, the gas is compressed by reducing the volume while moving around the compression chamber formed by both scroll members, and the compressed gas is sealed from the discharge port. In a closed type variable speed scroll compressor configured to discharge into an upper chamber in a container, lead to a lower chamber in a closed container via a passage, and discharge outside the closed container via a discharge pipe, the wrap of both scroll members The number of turns is approximately 2 to 2.5, a check valve mechanism is provided above the discharge port in the center of the end plate of the fixed scroll member, the electric motor is driven by an inverter, and the end plate of the orbiting scroll member is equipped with a check valve mechanism. A back pressure hole communicating between the compression chamber and a back pressure chamber provided on the back side of the end plate is provided at a position one turn inward from the end of the wrap,
A closed type variable speed scroll compressor characterized in that the innermost chamber in the center of the wrap formed by both scroll members and the back pressure hole are in a positional relationship such that they do not constantly communicate with each other. 2. When the tip of the central portion of the wrap of each scroll member is shaped into an arc, and the radius of the arc is Rc, and the radius of the base circle of the involute curve of the wrap is a, the radius ratio R_o/a is approximately 0.4. 2. The hermetic variable speed scroll compressor according to claim 1, wherein the hermetic variable speed scroll compressor has a wrap shape in which a ratio of a wrap height h_s to a wrap thickness t (h_s/t) is set to 6 or less. 3 A scroll compressor section and an electric motor section are housed in a sealed container, connected to each other via a main rotating shaft supported by a frame fixed to the sealed container, and the inside of the sealed container is divided into upper and lower chambers by the frame. In the scroll compressor section, a spiral wrap is erected on a disc-shaped end plate, and the fixed scroll member and the orbiting scroll member are engaged with each other with the wraps inside, and the orbiting scroll member is connected to the main rotating shaft. The fixed scroll member has a discharge port opening at the center and an intake port opening at the outer periphery. The gas is sucked in from the suction port, compressed by reducing the volume while moving around the compression chamber formed by both scroll members, and the compressed gas is delivered to the upper chamber of the closed container from the discharge port. In a closed type variable speed scroll compressor configured such that discharge is guided to a lower chamber in a closed container via a passage and discharged outside the closed container via a discharge pipe, the side space of the outer periphery of the end plate of the orbiting scroll member. An oil drain hole is provided in the end plate to return the oil accumulated in the compression chamber to the compression chamber, and the area of the oil drain hole is S.
Dimensionless area ratio S^* which is the ratio of the sum of __f and the area S_b of the back pressure hole provided on the back side of the end plate of the orbiting scroll member that communicates the back pressure chamber and the compression chamber, and the stroke volume V_t_k of the compressor. =(S_f+S_b)/V_t_k^3 is 0.0
A hermetic variable speed scroll compressor, characterized in that the diameters of the oil drain hole and the back pressure hole are set to be approximately 0.05 to 0.007. 4 The back pressure hole is provided at a position one turn inward from the end of the wrap, and the oil drain hole is set at an angle Δλ=t/a with respect to the back pressure hole.
A hermetic variable speed scroll compressor characterized in that it is installed at a position closer to the outside of the wrap (where a is the base circle radius of the involute curve of the wrap and t is the wrap thickness). 5. The hermetic variable speed scroll compressor according to claim 3 or 4, wherein the direction of the oil drain hole is set to be inclined in the advance direction at 45 degrees with respect to the direction of the orbiting motion of the orbiting scroll member. 6. Claims 1 to 5, wherein the fixed scroll member is made of iron-based material, and the orbiting scroll member is made of aluminum alloy material.
The hermetic variable speed scroll compressor according to any one of the above.