JP2002235683A - Scroll compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine an optimal lap thickness in a scroll compressor wherein a fixing scroll and a turning scroll made of aluminum compress CO2 coolant. SOLUTION: In this scroll compressor for CO2 coolant wherein spiral protrusions (laps) 11, 18 standingly mounted on the fixing scroll and the turning scroll made of aluminum form three compressing chambers P for compressing the CO2 coolant, the lap thickness (t) at a position inside by one roll with the outermost circumferential lap as an origin at a position shifted from a lap roll end on the outer circumferential side by 90 deg. is 5 mm or larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a scroll compressor used in an air conditioning system for vehicles, etc., in particular, carbon dioxide (CO ₂₎ or the like of the scroll which is suitable for vapor compression refrigeration cycle using a refrigerant in a supercritical range It relates to a compressor.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of environmental protection, carbon dioxide (CO ₂ ) has been used as a working gas (refrigerant gas) in a vapor compression refrigeration cycle as one of measures against defluorocarbon refrigerant.
(Hereinafter referred to as CO ₂ cycle) has been proposed (for example, Japanese Patent Publication No. Hei 7-18602). The operation of this CO ₂ cycle is similar to that of a conventional vapor compression refrigeration cycle using Freon. That is, ABCDA in the CO ₂ Mollier diagram of FIG.
As shown in (1), CO ₂ in the gas phase is compressed by the compressor (A-B), and the CO ₂ in the gas phase in the high-temperature compression is cooled by a radiator (gas cooler) (BC). Then, the pressure was reduced by a pressure reducer (C-D), and CO in a gas-liquid phase state was obtained.
₂ is evaporated (DA), and latent heat of evaporation is taken from an external fluid such as air to cool the external fluid.

Since the critical temperature of CO ₂ is about 31 °, which is lower than the critical point temperature of Freon, which is a conventional refrigerant, when the outside temperature is high such as in summer, the CO ₂ on the radiator side is high.
Is higher than the critical point temperature of CO ₂ .
That is, CO ₂ does not condense on the radiator outlet side (the line segment BC does not cross the saturated liquid line SL). The state of the radiator outlet side (C point), the discharge pressure of the compressor is determined by the CO ₂ temperature at the radiator outlet side, CO ₂ temperature at the radiator outlet side is a heat radiation capacity of the radiator outside air Temperature (uncontrollable)
And the temperature at the radiator outlet cannot be substantially controlled. Therefore, the state of the radiator outlet side (point C) can be controlled by controlling the compressor discharge pressure (radiator outlet side pressure). In other words, when the outside air temperature is high, such as in summer, in order to secure a sufficient cooling capacity (enthalpy difference), EFGHHE is required.
It is necessary to set the pressure on the radiator outlet side high as shown by. Therefore, the operating pressure of the compressor needs to be higher than that of a conventional refrigeration cycle using chlorofluorocarbon. Taking a vehicle air conditioner as an example, the operating pressure of the compressor is about 3 kg / cm ^{2 for} conventional R134 (Freon), about 40 kg / cm ² for CO ₂ , and the operation stop pressure is about 15k for R134 (Freon)
g / cm ² , whereas CO ₂ is 100 kg
/ Cm ² .

[0004]

SUMMARY OF THE INVENTION As described above, CO 2
_Since the operating pressure of the compressor used in the _two cycles is considerably higher than that of the conventional compressor that compresses CFCs, the spiral projections (wraps) provided on the fixed scroll and the orbiting scroll are sufficient. Countermeasures that can be tolerated are needed. In particular, scroll compressors used in vehicle air conditioners are also required to be smaller and lighter in weight, because the installation space is limited and the demand for weight reduction is severe. Against this background, in the case of aluminum fixed scrolls and orbiting scrolls, which are especially suitable for miniaturization and weight reduction, which are important in vehicle air conditioners, sufficient strength and durability to prevent damage even when operated using a CO ₂ cycle It is necessary to find an optimum value of the wrap thickness with the property.

The present invention has been made in view of the above circumstances, and an object of the present invention is to specify an optimum value of a wrap thickness in a scroll compressor in which a fixed scroll and an orbiting scroll made of aluminum compress a CO ₂ refrigerant. And

[0006]

The present invention employs the following means in order to solve the above-mentioned problems. Scroll compressor according to claim 1, for the CO ₂ refrigerant that is configured to wrap erected on aluminum fixed scroll and the orbiting scroll to form three compression chambers compresses the CO ₂ refrigerant The scroll compressor is characterized in that the wrap at a position which is one turn inside from the outermost wrap at a position shifted by 90 degrees from the end of the wrap winding on the outer circumferential side has a thickness of 5 mm or more.

According to such a scroll compressor of the present invention, even in the high pressure operation for compressing the CO ₂ refrigerant, the thickness is 5 mm or more at the position where the pressure condition is the strictest in the wrap, so that sufficient pressure resistance and durability can be obtained. It is possible to provide a scroll compressor which has a property and is not damaged.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the scroll compressor according to the present invention will be described below with reference to the drawings. First,
A CO ₂ cycle equipped with the scroll compressor of the present invention will be described with reference to FIG. This CO ₂ cycle S
Is applied to, for example, a vehicle air conditioner, and 1 is a scroll compressor that compresses CO _{2 in a} gaseous state. The scroll compressor 1 is driven by obtaining a driving force from a drive source (not shown) such as an engine. 1a is a radiator (gas cooler) for exchanging heat between the CO ₂ compressed by the scroll compressor 1 and the outside air or the like to cool the CO ₂ , and 1c is a radiator 1c
This is a pressure control valve that controls the pressure on the outlet side of the radiator 1a in accordance with the CO ₂ temperature on the outlet side. CO ₂ refrigerant is a CO ₂ for low-temperature low-pressure gas-liquid two-phase state is depressurized by the pressure control valve 1b and the diaphragm 1c. Reference numeral 1d denotes an evaporator (heat absorber) serving as an air cooling means in the vehicle compartment, which is a gas-liquid two-phase C
When O ₂ is vaporized (evaporated) in the evaporator 1d, the O ₂ removes latent heat of evaporation from the vehicle interior air to cool the vehicle interior air. 1e
Is an accumulator for temporarily storing CO ₂ in a gaseous state. The scroll compressor 1, the radiator 1a, the pressure control valve 1b, the throttle 1c, the evaporator 1d, and the accumulator 1e are respectively connected by a pipe 1f to form a closed circuit.

Next, an embodiment of the scroll compressor 1 will be described with reference to FIG. Scroll compressor 1
1A (casing) comprises a cup-shaped case main body 2 and a front case 4 (crankcase) fastened to the main body 2 by bolts 3. The crankshaft 5 penetrates the front case 4 and is rotatably supported by the front case 4 via a main bearing 6 and a sub-bearing 7. The rotation of the vehicle engine (not shown) is transmitted to the crankshaft 5 via a known electromagnetic clutch 32. Note that reference numeral 32
Reference numerals a and 32b denote a coil and a pulley of the electromagnetic clutch 32, respectively.

A fixed scroll 8 and an orbiting scroll 9 made of aluminum are disposed inside the housing 1A. Here, the term "made of aluminum" includes an aluminum alloy containing aluminum as a main component. The fixed scroll 8 includes an end plate 10 and a spiral projection 11 (wrap) provided upright on an inner surface thereof.
3 is detachably fixed by bolts 12. O-rings 14 are provided on the inner and outer peripheral surfaces of the back pressure block 13.
The O-rings 14a and 14b are closely buried in the inner peripheral surface of the case main body 2, and are connected to a low-pressure chamber 15 (suction chamber) in the case main body 2 from a high-pressure chamber (described later). The discharge chamber 16 is isolated. The high pressure chamber 16 includes an inner space 13 a of the back pressure block 13 and a concave portion 10 a formed on the back surface of the end plate 10 of the fixed scroll 8. The orbiting scroll 9 includes an end plate 17 and a spiral projection 18 (wrap) provided upright on the inner surface thereof. The spiral projection 18 has substantially the same shape as the spiral projection 11 of the fixed scroll 8. Have.

A ring-shaped leaf spring 20a is arranged between the fixed scroll 8 and the case body 2, and the leaf spring 20a is alternately arranged in the circumferential direction by a plurality of bolts 21b in the circumferential direction. Fastened to the body. Thereby, the fixed scroll 8 is allowed to move only in the axial direction by the maximum amount of deflection of the leaf spring 20a (float structure). The ring-shaped leaf spring 20
a and the bolt 20b for the fixed scroll support device 2
0 is configured. Since a gap c is provided between the back projection of the back pressure block 13 and the housing 1A, the back pressure block 13 is movable in the axial direction. The fixed scroll 8 and the orbiting scroll 9 are eccentric to each other by the orbital radius of rotation, and are engaged with each other with a phase shift of 180 ° as shown in the drawing, and a tip seal (not shown) embedded at the tip of the spiral projection 11. ) Is in close contact with the inner surface of the end plate 17, the tip seal (not shown) embedded at the tip of the spiral projection 18 is in close contact with the inner surface of the end plate 10, and Close contact at multiple locations. This limits the plurality of closed spaces 21a and 21b that are substantially point-symmetric with respect to the spiral center. An Oldham coupling 27 is provided between the fixed scroll 8 and the orbiting scroll 9 to prevent rotation of the orbiting scroll 9 and allow revolving. The Oldham coupling 27 is a mechanism for preventing the orbiting scroll 9 from rotating (a mechanism for preventing the relative rotation of the orbiting scroll 9 and the fixed scroll 8).

A drive bush 23 is rotatably housed inside a cylindrical boss 22 formed at the center of the outer surface of the end plate 17 via a swivel bearing 24 (drive bearing) also serving as a radial bearing. An eccentric shaft 26 projecting from the inner end of the crankshaft 5 is rotatably fitted into a through hole 25 formed in the drive bush 23. A thrust ball bearing 19 for supporting the orbiting scroll 9 is arranged between the outer peripheral edge of the outer surface of the end plate 17 and the front case 4.

A known mechanical seal 28 (shaft seal) is disposed on the outer periphery of the crankshaft 5. The mechanical seal 28 includes a seat ring 28 a fixed to the front case 4 and a crankshaft 5.
And a driven ring 28b that rotates together with the seat ring 2b by an urging member 28c.
8a, the crankshaft 5
Slides with respect to the seat ring 28a with the rotation of.

Next, the operation of the scroll compressor 1 will be described. When the coil 32a of the electromagnetic clutch 32 is energized and the rotation of the vehicle engine is transmitted to the crankshaft 5, the rotation of the crankshaft 5 is transmitted from the eccentric shaft 26, the through hole 25, the drive bush 23, the slewing bearing 24, and the boss 22. The orbiting scroll 9 is driven via the orbiting drive mechanism, and the orbiting scroll 9 orbits in a circular orbit having a radius equal to the eccentric amount of the eccentric shaft 26 while its rotation is prevented by the anti-rotation ring 17.

When the orbiting scroll 9 revolves orbits,
The line contact portions of the two spiral projections 11, 18 gradually move toward the center of the spiral, and as a result, the closed spaces 21a, 21
b (compression chamber) moves toward the center of the spiral while reducing the volume. As a result, the working gas (see arrow A) flowing into the suction chamber 15 through the suction port (not shown) flows from the outer terminal openings of the spiral projections 11 and 18 into the closed space 2.
1a, 21b while being compressed
1c, from here, passes through a discharge port 34 formed in the end plate 10 of the fixed scroll 8, pushes and opens the discharge valve 35, discharges into the high-pressure chamber 16, and further flows out from the discharge port 38. In this manner, the fluid introduced from the suction chamber 15 due to the rotation of the orbiting scroll 9 allows the closed spaces 21a, 21b
Compressed gas is discharged inside. Electromagnetic clutch 3
When the power supply to the second coil 32a is released and the transmission of the rotational force to the crankshaft 5 is stopped, the operation of the open-type compressor 1 is stopped.

The spiral projections 11 and 18 of the above-described scroll compressor 1 are located near the center of the inner periphery of the spiral where compression is the final stage (near the discharge port 34).
Have been considered to be in the most severe pressure conditions. However, the present inventors conducted various trial productions and tests to develop a scroll compressor for CO ₂ cycle. As shown in FIG. 1, the spiral projection 11 of the fixed scroll 8 and the spiral In the case where the three projections 18 form the three compression chambers P, the scroll wrap at the position one turn inside from the position shifted by 90 degrees from the end of the wrap winding on the outer peripheral side is under the most severe pressure condition. I found it. This is because the discharge port 34 is provided near the center of the inner peripheral side of the spiral and the upper limit of the pressure is limited because the discharge valve 35 is pushed and opened at a predetermined pressure. It is presumed that the pressure before P reaches the discharge port 34 may receive a higher pressure.

In view of the above, when the fixed scroll 8 and the orbiting scroll 9 made of aluminum suitable for weight reduction are adopted as the scroll compressor 1 for the CO ₂ cycle, the wrap thickness at the position where the above-mentioned pressure condition is strictest is considered. Examination of the optimum value of the thickness t revealed that if the wrap thickness t at the above-mentioned position is 5 mm or more, there is no practical problem, good pressure resistance and durability can be obtained, and no breakage occurs. That is, in the aluminum scroll compressor 1 that compresses the CO ₂ refrigerant, the spiral projections 11 and 18 are 3
In the case of forming one compression chamber P, the optimum value of the wrap thickness t at a position that is one turn inside from the position shifted by 90 degrees from the end of the wrap winding on the outer peripheral side is 5 mm or more. The wrap thickness t described above is applied to both the fixed scroll 8 and the orbiting scroll 9.

The spiral projections 11 and 18 described above are often made to have the same wrap thickness as a whole because they are easy to manufacture. Therefore, in such a case, the inner peripheral side starts from the outer peripheral side sowing. Until the end, the wrap thickness t mentioned above is 5m
There is no problem even if an optimum value of m or more is applied. Of course, the wrap thickness t at the position where the above-mentioned pressure condition is strict is set to an optimum value of 5 mm or more, and the weight can be further reduced by sequentially reducing the thickness on the inner circumferential side and the outer circumferential side.

In each of the above embodiments, the structure of the scroll compressor 1 is not limited to the above-described embodiment such as the housing structure, the float structure, and the Oldham joint. Any configuration may be employed as long as it does not deviate from the gist of the present invention.

[0020]

According to the scroll compressor of the present invention, the wrap thickness t at the position where the pressure acting on the wrap during compression is the strictest condition, that is, the wrap thickness t at the position shifted by 90 degrees from the end of the wrap winding on the outer peripheral side. The scroll wrap, which is positioned one turn inside from the outermost wrap, has a thickness of 5 mm or more, so that the aluminum fixed scroll and the orbiting scroll, which are used in the CO ₂ cycle and act on high pressure, are prevented from being damaged, Durability and reliability can be improved. In addition, since the optimum value of the aluminum wrap thickness used for the CO ₂ cycle was determined and specified, the wrap thickness was unnecessarily increased, so that miniaturization and weight reduction were not hindered. It is effective in a scroll compressor for use.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining an embodiment of a spiral projection (wrap) according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration example of a scroll compressor employing the spiral projection shown in FIG.

FIG. 3 is a diagram showing a configuration example of a CO ₂ cycle.

FIG. 4 is a Mollier diagram of CO ₂ .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scroll compressor 8 Fixed scroll 9 Orbiting scroll 11, 18 Spiral protrusion (wrap)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takahiro Ichiyanagi 1 Nagoya Research Laboratories, Mitsubishi Heavy Industries, Ltd. Nagoya Research Laboratories, Nagoya City, Aichi Prefecture 3-chome No.1 F-term in Mitsubishi Heavy Industries, Ltd. Cooling and Refrigerating Business Division 3H039 AA02 AA12 BB05 CC07 CC35

Claims (1)

[Claims] 1. A fixed scroll and orbiting scroll made of aluminum.
The wrap erected on the crawl forms three compression chambers
CO_Two CO configured to compress the refrigerant _Two For refrigerant
In the scroll compressor, the outermost side of the wrap around the end of the wrap is shifted by 90 degrees.
Wrap at a position that is one turn inside from the outer wrap
Characterized by having a thickness of 5 mm or more
Compressor.