JPH0587679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a scroll vacuum pump, and in particular to an improvement in an orbiting scroll.

(Prior Art) In recent years, various scroll-type vacuum pumps have been developed. This scroll-type vacuum pump includes a fixed scroll, an orbiting scroll, a rotating shaft with a crankshaft, and a casing, and the orbiting scroll is meshed with the fixed scroll. However, the orbiting scroll is made to revolve around the fixed scroll without rotating. And this orbiting scroll is
While the lap is erected on the front side of the head plate, the slewing bearing boss portion into which the slewing bearing fits is made of the same material and is shifted in the axial direction from the lap, that is, it is integrally formed on the back side of the head plate. .

(Problem to be Solved by the Invention) In the orbiting scroll of the conventional scroll type vacuum pump as described above, regardless of the material, the eccentricity of the crankshaft is A proportional centrifugal force and a force due to the gas pressure act as a moment, and the point of action is located at a certain distance in the axial direction from the swivel bearing. Therefore, this moment causes the orbiting scroll to flutter. Especially in vacuum pumps, the gas force that presses down the orbiting scroll in the axial direction is extremely small, so unless the overturning moment of the orbiting scroll due to centrifugal force is reduced, stable pump performance and reliability of the slat bearing cannot be obtained. There was the problem of inviting people.

In addition, as a measure to reduce the above-mentioned moment, some systems use light alloys with low specific gravity for the material of the orbiting scroll, but in this case, for example, if light alloys such as aluminum are used, the temperature rise during operation will cause the orbiting bearing boss to There was a problem in that the material expanded thermally to a large extent, making it difficult to fit into the outer ring of the slewing bearing, causing a creep phenomenon in the bearing.

The present invention has been made in view of the above points, and
The purpose is to prevent the orbiting scroll from flapping by bringing the center of gravity of the orbiting scroll close to the center of the orbiting bearing, and at the same time to prevent the occurrence of creep in the orbiting bearing.

(Means for Solving the Problems) In order to achieve the above object, the means taken by the present invention is to form at least the scroll main body from a non-ferrous metal material, and to make the entire or part of the swing bearing boss part from a ferrous metal material. It is made of metal material.

Specifically, the measures taken by the present invention include, first, a spiral wrap is erected on the front surface of the end plate, a fixed scroll fixed to the casing, and a spiral wrap is erected on the front surface of the end plate. A scroll main body is formed, and an orbiting bearing boss having a bearing retainer is formed on the back surface of the end plate, and the orbiting scroll is housed in the casing and is disposed by engaging the lap with the lap of the fixed scroll. and a rotating shaft with a crankshaft that has a crankshaft that fits into the orbiting bearing boss portion of the orbiting scroll, so that the orbiting scroll revolves around the fixed scroll without rotating on its own axis. It is a premise.

In the orbiting scroll, at least the scroll body is made of a non-ferrous metal material with low specific gravity. In addition, the entire or part of the swing bearing boss portion is formed of a divided boss made of a ferrous metal material with a high specific gravity and having a bottomless cylindrical portion. Further, the divided boss is fixed to the scroll body of the orbiting scroll or the main body of an orbiting bearing boss portion continuous to the scroll body by a fastening means, and the crankshaft is connected to the orbiting bearing boss portion. It has a structure in which a rolling type swivel bearing is fitted.

(Function) With the above configuration, in the present invention, when the rotating shaft is rotated, the orbiting scroll revolves around the fixed scroll without rotating on its own axis, thereby performing a pump operation.

During this operation, at least the scroll body of the orbiting scroll is made of a non-ferrous metal material with low specific gravity, so centrifugal force, etc. is small, and at least a part of the orbiting bearing boss is made of a ferrous metal material with high specific gravity. Since the center of gravity of the entire orbiting scroll in the axial direction is close to the axial center of the orbiting bearing, the length of the moment arm becomes small and the moment is reduced. As a result, the orbiting scroll is stable without flapping, and the thrust bearing is not adversely affected. Furthermore, since at least a portion of the pivot shaft boss is made of iron-based metal material, there is little adverse effect from thermal expansion, and the creep phenomenon of the pivot bearing does not occur.Moreover, the heat generated by the pivot bearing is transferred to both scrolls. The heat is transmitted and radiated into the atmosphere.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

As shown in FIGS. 1 and 2, reference numeral 1 denotes a fixed scroll in a scroll-type vacuum pump, and the wrap 1a is erected on the front (lower surface) of an end plate 1d which also serves as a lid of a casing 2. 1d
It is fixed to the casing 2 at the outer peripheral edge of. 3
1 is a rotating shaft with a crankshaft supported by the casing 2 via bearings 4 and 5, and a crankshaft 3a is integrally formed eccentrically at the upper end.

6 is a rolling type swing bearing 7 on the crankshaft 3a.
The divided boss fitted through the shaft constitutes the orbiting bearing boss portion of the orbiting scroll, which will be described later. The split boss 6 is composed of a thick-walled, substantially cylindrical bottomless cylindrical portion 6a, and a bearing retainer 6b formed with an inward flange at the lower end of the bottomless cylindrical portion 6a. .

8 is an orbiting scroll housed in the casing 2, and a wrap 8 is provided on the front (upper surface) of the mirror plate 8b.
a is erected to form a scroll main body 8c, and the divided boss 6 is attached to a thick back (lower surface) portion 8d of the end plate 8b by bolts 9 serving as fastening means. The orbiting scroll 8 is arranged such that the lap 8a meshes with the lap 1a of the fixed scroll 1.

Further, as a feature of the present invention, the scroll main body 8c is made of a non-ferrous metal material with a low specific gravity, such as an aluminum light alloy material, while the split boss 6 is made of a ferrous metal material with a high specific gravity.

10 and 11 are upper and lower sliding receiving members, 12 and 13
are upper and lower sliding members, and the upper sliding receiving member 10 and the upper sliding member 12 are engaged with each other, and the lower sliding receiving member 11 and the lower sliding member 13 are engaged with each other, so that the shaft of the orbiting scroll 8 They serve to regulate directional movement, that is, act as thrust bearings, and are arranged at multiple locations around the circumference, each of which is made of a lubricating member.

14 refers to a plurality of equally divided circumferential positions on the lower surface around the end plate 8b of the orbiting scroll 8 as a rotation prevention structure of the orbiting scroll 8, and the casing 2 as a fixed part.
A pink rank placed between the inner wall surface of the upper and
The lower pin portions are supported using ball bearings 15 and 16, respectively, and rubber O-rings 17 and 18 are used to prevent the bearings from slipping.

In addition, 1b is a suction port, 1c is a discharge port, 19 is a balance weight, 20 is a bearing retainer, and 21 is a seal.

Next, the operation of this scroll type vacuum pump will be explained.

First, due to the rotation of the rotating shaft 3 with a crankshaft, the orbiting scroll 8 performs a rotating movement around the rotating shaft 3, and as a result, the lamps 1a and 8a are engaged.
The fluid sucked through the suction port 1b is sequentially compressed and discharged from the discharge port 1c to perform a pumping action.

In this case, since the scroll body 8c of the orbiting scroll 8 is made of a light aluminum alloy material having a small material, the centrifugal force acting on the rotating shaft 3 is compared to the case of a normally used iron-based metal material with a large specific gravity. and decrease. In addition, since the split boss 6 is made of iron-based metal material with a high specific gravity, the axial center of gravity of the entire orbiting scroll 8 approaches the axial center of the orbiting bearing 7, and the arm of the moment acting on the bearing 7 Reduce the moment by shortening the length of
As a result, the orbiting scroll 8 is stable without flapping, and the thrust bearings 10, 12, 11, and 13 are not adversely affected. Moreover, since the orbiting scroll main body 8c is made of aluminum light alloy material, its thermal expansion coefficient is large, but since the split boss 6 is made of iron-based metal material, its thermal expansion coefficient is considerably smaller than that of aluminum light alloy material. Therefore, there is no fear that the outer side of the orbiting bearing 7 will cause a creep phenomenon when the temperature rises, which occurs when the entire orbiting scroll including the boss portion is made of light aluminum alloy. Further, the heat generated by the orbiting bearing 7 is transmitted from the center of the lower surface of the scroll body 8c, which is the bottom surface of the bottomless cylindrical portion 6a, to both scrolls 8,
1 and is radiated to the atmosphere.

In the above-mentioned embodiment, the orbiting scroll body 8 is made of an aluminum light alloy material with a low specific gravity, but the present invention is not limited to this.

Further, as a means for fastening the divided boss 6 and the orbiting scroll main body 8c, the bearing retainer 6b is further divided and bolted as separate parts, and the bottomless cylindrical part 6a corresponding to the bearing box part is attached to the orbiting scroll main body 8c. Alternatively, the divided boss 6 may be shrunk-fitted, or the split boss 6 may be appropriately stopped and cast into the scroll body 8c.

Next, a description will be given based on a second embodiment shown in FIG.

In this FIG. 3, 108 is an orbiting scroll, and a wrap 108a is attached to the front surface of an end plate 108b.
is erected to form the scroll main body 108c, and a swing bearing boss portion 106 is formed on the back surface of the end plate 108b. The pivot bearing boss portion 106 includes a divided boss 106 in a cylindrical main body portion 106c integrally formed with the end plate 108b.
d is attached, and the corresponding divided boss 106d
is divided into a ring 106a, which is a bottomless cylindrical portion, and a donut disk-shaped bearing retainer 106b. And the scroll body 108
c and the main body part 106c of the swing bearing boss part 106 are formed of aluminum light alloy material, while the ring 106a of the swing bearing boss part 106 and the bearing retainer 106b are made of aluminum light alloy material.
is made of iron-based metal materials.

Furthermore, the ring 106a is fitted onto the outer peripheral surface of the main body 106c, and the bearing retainer 106b is attached to the main body 106c with bolts 109.

In this case, during the orbiting movement of the orbiting scroll 108, the flapping phenomenon of the orbiting scroll 108 is prevented due to the difference in specific gravity of the ring 106a and the bearing retainer 106b with respect to the scroll body 108c, as in the case of the first embodiment described above. In Although,
Even if the main body part 106c of the swing bearing boss part 106 is made of aluminum light alloy material, the ring 106 fitted on the outer periphery
a prevents the inner diameter of the boss portion 106 from expanding due to thermal expansion, and as a result, the creep phenomenon of the swing bearing 7 does not occur as in the first embodiment.

(Effects of the Invention) As described above, in the scroll type vacuum pump according to the present invention, at least the scroll body of the orbiting scroll is made of a non-ferrous metal material with a low specific gravity, and at least a portion of the orbiting bearing boss portion has a low specific gravity. Since it is made of a large iron-based metal material, for example, if the scroll body is made of aluminum light alloy and all or part of the orbiting bearing boss is made of iron-based material, centrifugal force will be reduced by reducing the weight of the entire orbiting scroll. In addition, the overall axial center of gravity position almost coincides with the axial center of the slewing bearing, and the arm length of the moment of force due to centrifugal force and gas pressure, which is proportional to the eccentricity of the crankshaft acting on the rotating shaft. This is particularly effective in vacuum pumps because it shortens the length and reduces the moment, thereby preventing flapping and stabilizing the orbiting scroll when it orbits. Therefore, the pump performance can be improved and stabilized, and the reliability and life of the thrust bearing can be extended without adversely affecting the thrust bearing. Furthermore, even if a material with a large coefficient of thermal expansion, such as an aluminum light alloy, is used for the scroll body, there is no risk of creep occurring in the orbiting bearing.

Furthermore, since the divided boss has a bottomless cylindrical portion, the heat of the orbiting bearing is reliably radiated to the atmosphere through both scrolls, and the reliability of the bearing can be improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention, and FIG. 2 is an enlarged detailed view of the main part in FIG. 1. FIG. 3 is an enlarged detailed view of a main part similar to FIG. 2, showing a second embodiment. 1...Fixed scroll, 1a, 8a, 108a
...Lap, 1d, 8b, 108b... Mirror plate, 3
...Rotating shaft with crankshaft, 3a...Crankshaft, 6,106d...Divided boss, 6a...Bottomless cylindrical part, 6b, 10b...Bearing retainer, 7...Orbiting bearing, 8...Orbiting scroll , 106...Swivel bearing boss part, 106a...Ring, 106c... Main body part.

Claims (1)

[Scope of Claims] 1. A scroll main body is formed by a spiral wrap erected on the front surface of the end plate, a fixed scroll fixed to the casing, and a spiral wrap erected on the front surface of the end plate. In addition, an orbiting bearing boss portion having a bearing retainer is formed on the back surface of the end plate, and the orbiting scroll is housed in the casing and is disposed with its lap meshing with the lap of the fixed scroll; A scroll-type vacuum pump comprising a rotating shaft with a crankshaft that has a crankshaft that fits into an orbiting bearing boss portion, and wherein the orbiting scroll revolves around the fixed scroll without rotating, the orbiting scroll having at least While the scroll body is made of a non-ferrous metal material with a low specific gravity, the entire or part of the swing bearing boss part is made of a ferrous metal material with a high specific gravity and is composed of a divided boss having a bottomless cylindrical part. , the divided boss is fixed by a fastening means to the scroll body of the orbiting scroll or the main body of an orbiting bearing boss portion continuous to the scroll body, and the orbiting bearing boss portion is a rolling type orbiter that connects the crankshaft. A scroll-type vacuum pump characterized by a fitted bearing. 2. The bottomless cylindrical portion of the split boss in the swing bearing boss is comprised of a ring that is made of a ferrous metal material with a high specific gravity and is fitted onto the outer peripheral surface of the main body of the swing bearing boss. A scroll type vacuum pump according to claim 1. 3. The split boss is composed of a ring made of a ferrous metal material with high specific gravity and fitted onto the outer peripheral surface of the main body of the swing bearing boss, and a bearing retainer made of a ferrous metal material with a high specific gravity. A scroll type vacuum pump according to claim 1, characterized in that: