JPH0684753B2 - Scroll type vacuum pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a scroll type vacuum pump, and in particular to a thrust receiver suitable for maintaining a stable motion of an orbiting scroll when used as a non-lubricated vacuum pump. Scroll type vacuum pump.

[Conventional technology]

In the conventional scroll type fluid machine, as described in Japanese Patent Laid-Open No. 58-57002, the thrust receiving structure of the orbiting scroll has the end plate surface of the orbiting scroll coated with a sliding compatible material or the base material is quenched. It was processed and locally hardened. Since the orbiting scroll is pressed against the fixed scroll side by gas pressure from the back portion thereof, the thrust receiver is disposed at a location facing the orbiting scroll and the end plate sliding portion of the fixed scroll.

Further, as described in JP-A-59-58188, there is disclosed an oil-free scroll fluid machine in which a plate member for non-lubrication sliding is provided in a groove of a frame seat surface and a groove provided in a fixed scroll end plate. There is.

[Problems to be Solved by the Invention]

When the scroll type fluid machine is used as a non-lubricated vacuum pump, the pressure ratio of suction and discharge is very large, and the sealed space (working chamber) formed by the scroll wraps has high sealing performance to ensure high performance. More strongly desired. On the other hand, during operation, the centrifugal force of the orbiting scroll itself causes a "miso-sorry motion", but because of the vacuum operation, the "sorry motion" is suppressed at the back of the orbiting scroll to provide a stable motion. The gas pressure force (back pressure) does not work. Therefore, the sandwich clearance of the thrust receiving portion directly affects the axial gap between the scroll wraps. For these reasons, the wear of the thrust receiver causes a significant deterioration in the vacuum exhaust performance. On the other hand, in the known technology, the amount of wear may be large even in the treated thrust receiving portion for a long period of operation or a long-term operation without lubrication. Furthermore, since the thrust portion of the back of the orbiting scroll is not treated, abnormal wear occurs even in a short-term operation, and the operation becomes impossible. In such a case, the known technique has a fatal defect that the main parts such as the orbiting scroll and the fixed scroll cannot be used.

Next, according to Japanese Patent Application Laid-Open No. 59-203893, a pin crankshaft is applied as a rotation preventing component of an orbiting scroll, and a thrust receiving member which is a separate member is arranged on a stationary member to support and move the orbiting scroll. It is disclosed that guides. However, in the present invention, although the orbiting scroll has sufficient positioning ability with respect to vertical translation, the thrust receivers that support the orbiting scroll have different distances from the center. However, it is in a state where it cannot exert its effect against the "misoratory motion" (fluttering) of the orbiting scroll. Then, in this case, this "miso shaving motion" is to be received by the upper pin crankshaft and the lower thrust receiving portion. Therefore, in addition to the rotation preventing force of the orbiting scroll, a force due to flapping acts on the pin crankshaft. The force of this flapping causes the pin crankshaft bearing to
It is difficult for the rolling elements to move on the regular rolling surface, and the bearing life is extremely short. Further, according to the disclosed example, the position adjusting means of the thrust receiving member is provided in the stationary member, but the flatness or the positioning accuracy of the thrust receiving member in practical use is in the range of ten and several μm or less. Due to the need to do so, this requirement has not been fully considered. Further, in order to compensate for the wear of the thrust receiver, in the disclosed structure, the machine must be disassembled once and repositioned, and the orbiting scroll end plate portion that abuts is also worn. It had the drawback of being very difficult.

Further, the one disclosed in Japanese Patent Laid-Open No. 59-58188 has a drawback that the orbiting scroll end plate portion is worn although the frame seat surface and the fixed scroll have thrust receiving portions. Moreover, since the scroll is fitted in the groove, the entire scroll must be replaced, and the pin crank slides.

In short, the above-mentioned conventional technology does not give sufficient consideration to the case of vacuum operation without lubrication, and does not consider the thrust receiving structure of the orbiting scroll and the relative positional relationship with the pin crankshaft. When the scroll or fixed scroll and the thrust receiving part such as the frame are worn, the axial gap between the scroll wraps is increased by that amount, resulting in a significant decrease in performance.Therefore, the problem that these major parts cannot be reused However, there is a problem in that the amount of "fluttering" of the orbiting scroll increases due to the above-mentioned wear, and the moment load acts on the pin crank excessively by that amount, which shortens the life.

It is an object of the present invention to attempt to achieve long-term reuse by compensating for the wear of the thrust parts of main parts such as the frame as well as the orbiting and fixed scrolls, and at the same time providing the thrust receiving part. By specifying the relative positional relationship with the pink rank shaft to reduce the moment load that acts on the pin crank shaft and extend the life of the pin crank shaft, the rubbing motion of the orbiting scroll is suppressed by the thrust receiving part, The aim is to stabilize and maintain an appropriate axial gap between scroll wraps.

[Means for Solving the Problems]

In order to achieve the above object, a scroll type vacuum pump of the present invention forms a closed space by engaging a wrap of a fixed scroll and a wrap of an orbiting scroll, and a plurality of pin cranks provided on an outer peripheral portion of the orbiting scroll. The rotation of the closed space is prevented by the rotation of the fixed scroll, and the closed space is reduced by the orbiting scroll driving main shaft that is pivotally supported by the frame connected to the fixed scroll and engaged with the center of the orbiting scroll. In a scroll-type vacuum pump that sucks fluid from the outer peripheral side, compresses it, and discharges it, a separate first thrust receiving member is detachably disposed on both sides of the orbiting scroll end plate portion, and is opposed thereto. A separate second thrust receiving member can be attached to and detached from the fixed scroll end plate surface and the frame, respectively. The thrust receiving member disposed on the side provided with the bearing for axially supporting the pin crank is formed in a plurality of annular flat plate shapes. And a bearing portion that axially supports the pin crank is a divided portion thereof, and is located within an extension line of the inner and outer edges when the annular inner and outer edges of the thrust receiving member are concentrically extended, respectively. And the width of the first thrust receiving member is Wm,
When the width of the second thrust receiving member is Wf and the turning radius is ε, 2ε + Wm> Wf ≧ Wm> 2ε.

[Action]

Since a separate thrust receiving member is detachably provided on both sides of the outer peripheral portion of the orbiting scroll end plate, and a similar thrust receiving member is detachably provided at a position opposite to this, a scroll vacuum pump is provided. If the thrust receiving member wears after being operated in a non-lubricated state for a long period of time, the main body of the main component can be reused only by replacing the thrust receiving member with a new one. As a result, the axial gap of the scroll wrap can always be maintained in an appropriate state, and a vacuum pump having high exhaust performance can be obtained.

Further, by disposing the pin crank in the concentric circle with the annular thrust receiving portion, it is possible to minimize the influence of the vertical movement due to the flapping of the orbiting scroll, so that the load on the pin crank can be reduced.

Furthermore, since the outer peripheral portion of the orbiting scroll is sandwiched between the thrust receiving members on the same circumference so as to be sandwiched, it is easy to stabilize the operation of the orbiting scroll. In other words, by specifying the relative position of the thrust receiving part and the pin crank bearing part, it is easy to create the flatness of the thrust part in machining for stable support of the orbiting scroll, and the gap between the scroll laps is maintained with high accuracy. can do.

In addition, since the thrust receiving members, which have a small amount of wear and a small friction coefficient, slide in a non-lubricated state, the life and efficiency are improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. As shown in the figure, a fixed scroll 1 which also serves as a casing is connected to a frame 5. The frame 5 has bearings 14a,
A crankshaft-equipped main shaft 7b is supported via 14b, and a eccentric crankshaft portion 7a is integrally formed at the upper end of the main shaft 7b. An orbiting scroll 2 is disposed in a space surrounded by the fixed scroll 1 and the frame 5, and the orbiting scroll 2 is engaged with a crankshaft 7a through a bearing 8 so that the wrap 2a is fixed to the fixed scroll. It meshes with the 1 lap 1b.

The pin crank 9 arranged as a rotation preventing mechanism of the orbiting scroll 2 is arranged on the lower surface of the outer peripheral portion of the end plate of the orbiting scroll 2 and the inner wall surface of the frame 5 as a stationary portion. That is, the upper pin of the pin crank 9 is supported by the bearing 10 provided on the orbiting scroll 2 side, and
The lower pin of is supported by the bearing 11 attached to the frame 5 side.

Thrust receiving portions 6a, 6b, 6c, 6d that act as thrust supporting mechanisms of the orbiting scroll 2 are attached such that 6a, 6b face the upper surface of the outer peripheral portion of the fixed scroll 1 and the orbiting scroll end plate 2a, respectively. At the same time, the thrust receiving portions 6c and 6d are attached so as to face the lower surface of the outer peripheral portion of the orbiting scroll end plate 2a and the frame, respectively.

The spindle 7b is provided with a balance weight 12 near the orbiting scroll 2 and a counterweight below. Furthermore, the bearing retainer 13 engaged with the frame 5
Inside, a shaft sealing means 17 is provided between the shaft and the main shaft.

Next, the detailed structure of the thrust receiving portion will be described with reference to FIGS. FIG. 2 shows the frame 5 in which the orbiting scroll 2, the main shaft 7 and the balance weight 12 are omitted in the AA arrow view of FIG. The thrust receiver 6d provided on the frame 5 is annularly divided into three parts, and the pin cranks 9 are arranged at equal intervals in the divided parts.
The thrust receiving member 6d can be attached / detached with a fixing bolt 20a. The pink rank shaft is arranged so as to be located within an extension line of the outer circumference of the annular thrust receiving member 6d. FIG. 3 shows the lower surface of the orbiting scroll end plate 2 in the BB arrow view of FIG. The thrust receiving member 6c is arranged on the outer peripheral portion of the orbiting scroll 2 in an annular manner and is divided into three parts.
Are arranged at the divisions of the annular thrust receiver 6c and within the extension lines of the inner and outer edges of the thrust receiver. The width of the thrust receiving member 6 is provided in the following relationship. That is, when the eccentric amount of the crankshaft 7a with respect to the main shaft 7b is ε, the width W _{m of the} thrust receiving member provided in the orbiting scroll 2 is
Is the width W _m ≧ 2ε of 6b and 6c, while the thrust receiving member on the fixed side (for example, the frame 5)
For 6d, its width W _f is 2ε + W _m > W _f ≧ W _m . The reason for setting in this way is as follows. First, as shown in FIG. 6, thrust receiving members 6b, 6
Considering the case where the width of c is Wm <2ε, the load distribution acting on the thrust receiving member is as shown in FIG. 6 from the axial center of the pin crank 9 on the frame 5 side with the turning motion of the pin crank. Since they are located apart from each other, the overturning moment acts on the shaft of the pin crank 9 on the frame 5 side. Further, since the width of the thrust receiving member is small, the thrust receiving members 6a and 6d are rubbed by the thrust receiving members 6b and 6c so as to sharpen the blade, and the wear of the thrust receiving members 6a and 6d is accelerated. . As a result, the positioning accuracy (thrust direction) of the orbiting scroll deteriorates, and it becomes difficult to secure the motion stability of the orbiting scroll. When the wear of the thrust surface is further promoted, the pincrank 9 takes on the overturning moment of the orbiting scroll.
Repetitive load is applied, resulting in reduced reliability. The above-mentioned configuration is for solving the drawbacks that have occurred in such an actual machine.

Next, considering the case of Wm = 2ε, the thrust receiving member 6
The load distribution acting on b and 6c is as shown in Fig. 7,
At least the axial center of the pin crank 9 on the frame 5 side and the ends of the thrust receiving members 6b, 6c are always aligned with each other, so that the overturning moment can be received. Since Wm> 2ε, the overturning moment can be always received and the thrust can be received in a wide range, so that the ratio of the unbalanced load to the moment load is small.
In this way, the pin crank 9 can always be arranged in the overlapping plane of the thrust load, and the extent to which the pin crank receives the overturning moment can be reduced.

Next, the reason why Wm + 2ε> Wf is set is that the orbiting scroll only moves 2ε with the orbiting motion.
This is because the overlapping width does not change even if Wf is made larger. FIG. 4 is a view of the orbiting scroll 2 as viewed from above (the side where the scroll wrap is located). The thrust receiving portion 6b is annularly arranged on the outer peripheral portion of the end plate. At this time,
As another embodiment, it is possible to use the thrust receiving member 6c as shown in FIG. 3 and share the member.
As the thrust receiving member 6a, although not shown, 6d shown in FIG. 2 can be used, but the width can be used as W _{f to} form an annular shape as shown in FIG. FIG. 5 is a cross-sectional view of the thrust receiving member 6, and is a typical embodiment in which the fixed component is the frame 5. The thrust receiving member 6 is provided on its sliding surface with a composite polymer material mainly containing tetrafluoroethylene resin and polyimide resin.

At this time, since the thrust receiver is composed of separate parts, this material should be of the same type as each main part, and the amount of thermal expansion should be matched and the surface (sliding surface)
It is even more desirable to provide a coating layer of a composite polymer material mainly composed of tetrafluoroethylene resin and polyimide resin, which is suitable for non-lubrication sliding.

For fixing to the frame 5, a fixing bolt 20 is arranged so as to be embedded in the thrust receiving member 6, and is tightened with a screw.

Next, the operation of the scroll type vacuum pump will be described. In FIG. 1, when the main shaft 7 is rotationally driven, the orbiting scroll 2 makes an orbiting motion around the main shaft 7 while being prevented from rotating by the pin crank 9, and thereby the wrap 1
The contact positions of b and 2b are sequentially moved toward the central portion, and a compression action of sequentially compressing the fluid sucked from the suction port 3 and discharging it from the discharge port 4 is performed. During this compression operation, the orbiting scroll 2 makes an orbiting motion while its axial movement is restricted only by the thrust receiving portion 6. Therefore, at this time, the thrust receiving member 6 can completely receive the "misalignment motion" or "flapping motion" due to the overturning moment of the orbiting scroll 2 itself.

After long-term operation, it was found through experiments that a plurality of local sliding marks were generated on the surface of the thrust receiving portion 6, but if the amount of wear progressed to such an extent that it did not reach the performance, By simply replacing the thrust receiving portion 6 with a new one, the scroll members 1, 2, etc., which are time-consuming to manufacture, can be reused.

Further, since the thrust receiving member 6 is formed in an annular and flat plate shape, the surface accuracy can be improved, and the motion of the orbiting scroll can be guided more smoothly. Further, the thrust receiving member 6 has the same annular shape. Since the pin crank is located on the orbiting scroll 2 that acts on the pin crank
The overturning moment of can be reduced.

Further, the material of the thrust receiving member 6 is the same as the material of the mounting partner (frame 5 in FIG. 5), so that it is excessive in the mounting portion against thermal expansion caused by heat generated during operation. Generation of stress can be prevented. In particular, in the orbiting scroll 2, it is possible to prevent the entire shape from being curved due to the difference in thermal expansion, and prevent the scroll wrap from colliding with or separating from the fixed scroll wrap.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a material having a small amount of wear and a small friction coefficient on the surface of the thrust receiving member in a non-lubricated state, and by making the thrust receiving member detachable, Even if operated as a lubrication type scroll vacuum pump, the thrust receiving members slide, so that it is possible to obtain a highly accurate and highly reliable thrust support mechanism for an orbiting scroll. Further, when the thrust receiving portion 6 is worn to such an extent that the performance is affected by long-term operation, at worst, all the thrust receiving members need to be replaced, and it is easy to obtain a functionally almost reliable initial state. It can be reproduced. By comparison, the cost can be reduced by a factor of about 10 compared to the conventional technique of replacing all major parts with new ones when worn.

Further, in the pin crank bearing 10, the overturning moment can be reduced, and the rolling elements inside the pin crank bearing 10 can move in a normal state, so that the life can be extended.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a scroll type fluid machine showing an embodiment of the present invention. FIG. 2 is a frame viewed from AA in FIG. FIG. 3 is a view on arrow BB in FIG. FIG. 4 is a front view of the orbiting scroll of the present invention.
FIG. 5 is a cross-sectional view showing a mounted state of the thrust receiving member of the present invention, and FIG. 6 shows a width of the thrust receiving member of Wm <2ε.
FIG. 7 is a cross-sectional view showing a case where the width of the thrust receiving member is Wm = 2ε. 1 ... Fixed scroll, 2 ... Orbiting scroll, 5 ...
Frame, 6 ... Thrust receiver, 7 ... Spindle, 9 ... Pin crank, 10, 11, 14 ... Bearing, 12 ... Balance weight, 17 ... Shaft sealing means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shin Uenishi Shin 1-1, Shinmeiwa-cho, Takarazuka-shi, Hyogo Prefecture Industrial Machinery Division, Shinmeiwa Industry Co., Ltd. (72) Inventor Naoki Maeda 502 Kandachicho, Tsuchiura-shi, Ibaraki Prefecture Address In the Institute of Mechanical Research, Hiritsu Seisakusho Co., Ltd. (72) Inventor Kazuaki Miyazaki 1-1, Shinmeiwacho, Takarazuka-shi, Hyogo Shinmeiwa Industry Co., Ltd. (56) Reference JP-A-59-58188 ( JP, A)

Claims (2)

[Claims] A wrap of a fixed scroll and a wrap of an orbiting scroll are engaged with each other to form a closed space, and a plurality of pin cranks provided on the outer peripheral portion of the orbiting scroll prevent rotation of the wrap and the fixed scroll. The closed space is contracted by performing the orbiting movement by the orbiting scroll driving main shaft that is pivotally supported by the frame to be coupled and is engaged with the center of the orbiting scroll, and sucks and compresses the fluid from the outer peripheral side. In the scroll type vacuum pump for discharging by means of the above, a separate first thrust receiving member is detachably disposed on both surfaces of the orbiting scroll end plate portion, and the fixed scroll end plate surface and the frame facing each other are separately provided. A second thrust receiving member of the body is detachably arranged to sandwich the orbiting scroll. The thrust receiving member arranged on the side on which the bearing supporting the pin crank is provided is formed into a plurality of annular flat plates, and the bearing supporting the pin crank is supported. Is a divided portion of the thrust receiving member, and the annular inner and outer edges of the thrust receiving member are arranged so as to be located within the extension lines of the inner and outer edges of the thrust receiving member when they are extended concentrically. Wm, the width of the second thrust receiving member is Wf, and the turning radius is ε. 2ε + Wm> Wf ≧ Wm> 2ε. 2. The thrust receiving member according to claim 1, wherein a base metal is formed of the same kind of material as the respective base materials, and a tetrafluoroethylene resin and a polyimide resin are main components on the surface thereof. A scroll-type vacuum pump characterized by being provided with a composite polymer material.