JP2003301784A - Rotation preventing mechanism of scroll fluid machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation preventing mechanism for a scroll fluid machine as improvement of the conventional technique involving such a problem where an excessive load acts on each bearing to result in its breakage in the case pin crank mechanisms installed at a constant pitch on a circumference for coupling the end plate of a revolving scroll with a frame mechanically have poor positional accuracy relative to one another or owing to prying generated between the bearings with one another originating from a deformation, etc., of the revolving scroll. <P>SOLUTION: The scroll fluid machine is composed of: pin crank shafts each formed of a supporting shaft in columnar shape and an eccentric shaft in prism shape installed eccentrically to the same degree as the revolving axis of a shaft with respect to the axis of the supporting shaft; a pin shaft bushing installed on the eccentric shaft and provided with a rectangular hole in the column; a resilient member installed between the eccentric shaft and the pin shaft bushing; and the pin crank mechanisms formed by inserting the pin shaft pushing and each pin crank shaft in a bearing fixed to the revolving scroll and the frame. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-free scroll fluid machine applied to a compressor for air using a gas as a working fluid, and further to a vacuum pump, and more particularly to a bearing structure including a rotation preventive mechanism of an orbiting scroll. Regarding

[0002]

2. Description of the Related Art Two scroll members each having a spiral wrap provided on one side of an end plate form a set, and the wraps are engaged with each other to form a working chamber and the set of scrolls.
Through a rotation preventing mechanism that mechanically couples the rolling members to each other, the working gas is swung relative to each other to suck the working gas into the working chamber from the outer circumference of the scroll member and compress it to discharge it as high pressure gas in the central portion. Many working examples of the principle of operation of the scroll fluid machine that flows out from the outlet are shown.

In an oil-free scroll fluid machine, which is composed of a fixed scroll having one of the scroll members fixed and a revolving scroll having the other revolving or rotating without rotation, At the same time as mounting the rolling bearing on the slewing bearing for transmitting power installed in the center of the slewing scroll, at the same time, a plurality of pin crank mechanisms supported by the rolling bearing as a rotation preventive mechanism are fixed to the slewing scroll. It is provided between the frame and the fixed scroll. For example, as a publicly known example thereof, JP-A-11-148
There are Japanese Patent No. 467 and Japanese Patent Laid-Open No. 2002-227779.

Further, in a scroll fluid machine based on oil lubrication, a variable crank mechanism is provided by providing a slide bush as a separate body between a slewing bearing integrated with a slewing scroll and an eccentric shaft. Japanese Patent Laid-Open No. 08-247050 is known as a known example. In this case, during operation, due to the centrifugal force of the orbiting scroll, the orbiting scroll is operated.
Are pressed against the fixed scroll side to make a swirling motion in a state where they are in contact with each other between the spiral wrap side walls.

[0005]

In a conventional scroll fluid machine using a pin crank mechanism, a swivel scroll machine is used.
The amount of radial movement of the roller is 3
The radial clearance of the rolling bearings provided in the pin crank mechanism and the mutual positional accuracy are roughly determined by the inclination and deformation of the shafts that support them.

Excessive load due to twisting between bearings due to poor relative positional accuracy of pin crank mechanisms arranged at three equal pitches on approximately the same circumference or deformation of the orbiting scroll. Causes damage to each bearing and it is necessary to support this excessive load, and the bearing becomes large.In order to avoid this excessive load, it is necessary to support the bearing with an elastic body and improve productivity. There was a problem that it greatly reduced.

Moreover, since the radial movement amounts of the slewing bearing and the bearings provided in the three pin crank mechanisms are approximately the same, the bearing that receives the centrifugal force of the slewing scroll is not specified. There were problems such as large size and reduced productivity due to the large bearings that were supposed to be received by the pink rank mechanism.

An object of the present invention is to reduce the load acting on the pin crank mechanism significantly and to reduce the relative positional accuracy between bearings, so that it is small and lightweight, highly reliable, and highly productive. It is an object of the present invention to provide an oil-free scroll fluid machine equipped with a pin crank mechanism which is improved.

[0009]

Power is transmitted from a shaft through a slewing bearing provided in a bearing boss in the center of a slewing scroll, while a rotation moment acts on the slewing scroll. Is received by a pin crank mechanism which is a rotation preventing mechanism provided at three locations on the outside of the end plate at approximately equal pitches.

A rolling bearing having at least one cylindrical or conical rolling element capable of supporting an axial load generated by gas compression or a plurality of rolling bearings including a pair of angular ball bearings. Is mounted in the bearing boss of the orbiting scroll.

On the other hand, a plurality of rolling bearings including at least one cylindrical or conical rolling element for supporting an axial load provided in the frame bearing boss or a plurality of rolling bearings including a pair of angular contact ball bearings. A shaft is composed of a supported main shaft and a swivel shaft which is eccentric from the main shaft and is inserted into the swivel bearing.

A pin crankshaft formed by an elongated columnar support shaft and a prismatic eccentric shaft that is eccentric to the central axis of the shaft about the same as the turning axis of the shaft, and a cylinder mounted on the eccentric shaft. A pin shaft bush 8 having a rectangular hole formed therein, an elastic body 9 formed between a spring and a rubber plate mounted between the eccentric shaft and the pin shaft bush, and the pin shaft bush being turned on the rear side of the end plate. Pin crank element, which is configured to be inserted into a fixed eccentric pin bearing of FIG. 1 and a supporting pin bearing of the pin crank shaft is inserted into a supporting pin bearing fixed to a frame. Is configured.

A step is formed on the end surface of the pin shaft bush rectangular hole into which one end of the elastic body is mounted so that the supporting shaft side becomes higher. The elastic body is hooked on this step and mounted on the eccentric shaft. The pin shaft bush is configured so as not to come off in the axial direction.

Furthermore, the direction in which the pin shaft bush moves within the eccentric shaft during operation is approximately equal to the direction in which the swivel shaft is eccentric with respect to the main shaft of the shaft, that is, the direction in which the centrifugal force of the swirl scroll acts. The direction of eccentricity of the eccentric shaft with respect to the support shaft of.

Therefore, one surface of the prismatic column on the side on which the load of the rotation moment acts is formed as a flat surface so as to be approximately parallel to the eccentric direction of the eccentric shaft with respect to the support shaft of the pin crankshaft. ing.

The direction in which the elastic force of the elastic body 9 which is housed in the eccentric shaft and pushes the pin shaft bush 8 from the inside acts also matches the moving direction of the pin shaft bush. The magnitude of Fk, which indicates the total of approximately the same number of elastic forces as the pink rank element, is given by the following equation. Fk> 2 × R × H × (Pd−Ps) where R is the radius of the basic circle of the involute curve forming the wall surface of the working chamber, H is the height of the wall surface, and Pd and Ps are the discharge pressure, respectively. It represents the suction pressure.

As another invention, the flat surface of the eccentric shaft that determines the moving direction of the pin shaft bush is inclined so that the outer side away from the supporting shaft center of the eccentric shaft escapes. And when inclining, the said elastic body in an eccentric shaft may be abolished.

The inclination angle θ of the eccentric shaft is set so as to satisfy the following equation. Ft × sin θ> Fr × cos θ where Fr is the gas load in the direction opposite to the radial or centrifugal force generated by gas compression, and Ft is the direction perpendicular to the tangential or centrifugal force generated by gas compression. Represents the gas load of.

The value of the tilt angle θ is preferably close to the value obtained by replacing the inequality sign in the above equation with an equal sign. Usually, the value of θ should be set between 5 and 20 °.

The function of the present invention configured as described above is as follows. Before the operation, the elastic body 9 pushes the orbiting scroll in the direction in which the gap between the side walls of the laps is reduced. Therefore, at the same time when the operation is started, the gas is compressed with a small amount of leakage and the efficient operation can be performed. The rising characteristics are improved.

In an operating state in which the operation is further continued and the discharge pressure reaches a predetermined value, the centrifugal force of the orbiting scroll 2 associated with the orbiting motion causes the pin shaft bush 8 to flatten the eccentric shaft of the pin crank shaft. Since it is possible to move in the direction of the centrifugal force along the surface, the centrifugal force is entirely received by the slewing bearing without acting on the pin crank mechanism.

The load due to the gas compression acting on the swirl scroll is a tangential force perpendicular to the lap side wall surface of the working chamber and in a direction for preventing the revolution motion of the swirl scroll, and a centrifugal force in a direction perpendicular to this. Direction radial force and shaft axis direction swivel scroll wrap tip fixed scroll
Can be decomposed into thrust force acting in the direction of separating from

The tangential force is the basis of the shaft torque of the shaft and also causes the rotation moment of the orbiting scroll. The rotation moment is received by the flat surface of the pin crankshaft eccentric shaft 7a from the eccentric pin bearing through the flat surface of the rectangular hole 8b of the pin shaft bush, whereby the rotation of the orbiting scroll is prevented.

On the other hand, the radial force acts against the centrifugal force of the orbiting scroll and the elastic force of the elastic body 9, but since the magnitude thereof is smaller than the centrifugal force or the elastic force, the pin shaft bush can move. Since it acts in the direction, it does not act directly on the pin crank mechanism, and the load is received by the slewing bearing.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the first invention is shown in FIG.
From now on, referring to FIG. FIG. 1 is a sectional view of an oil-free scroll fluid machine used in an air compressor and a vacuum pump according to an embodiment of the present invention.

The working chamber for confining and compressing the working gas in a closed space is provided with a fixed scroll 1 provided with a wrap which is a spiral groove or a projection, and a wrap which is a spiral projection on one surface of the end plate. It is formed by engaging the turning scrolls 2 with each other. Then, a tip seal intended for the seal in the working chamber is provided in a spiral groove provided at the tip of the wraps.
Are installed.

A shaft 4 for transmitting power of an electric motor or the like is supported by two rolling bearings, a main bearing 17 and a sub-bearing 18, which are mounted at approximately the center of the bearing boss 3a of the frame, while one end of the shaft 4 is supported. The eccentric turning shaft 4a to be formed has a bearing boss 2d which is provided approximately in the center of the turning scroll 2.
It is inserted into a first slewing bearing 14 and a second slewing bearing 15 which are rolling bearings fixed to an inner boss hole.

The first slewing bearing 14 and the second slewing bearing 15
Either one of them is provided with a rolling bearing or a pair of angular contact ball bearings having a cylindrical or conical rolling element for supporting a thrust load due to gas compression, and at the same time, a main bearing fixed to the frame. A rolling bearing or a pair of angular contact ball bearings having a cylindrical or conical rolling element for supporting a thrust load is provided on either one of 17 and the sub bearing 18, and oil or oil used for the sub bearing 18 is provided outside thereof. An oil seal 19 is attached to prevent the grease from flowing out.

For the purpose of blocking the space inside the bearing boss 3a and the discharge space provided on the fixed scroll side, a seal cover provided with an O-ring on the outer periphery on the discharge space side inside the swivel scroll bearing boss 2d. -16 is attached.

As shown in FIG. 2, which is an enlarged view of the arrow P of FIG. 1, as a rotation preventing mechanism for preventing rotation about the eccentric axis acting on the turning scroll 2, a turning scroll end plate 2a is provided.
The pin crank element 6 composed of the eccentric pin bearing 12 provided in the pin bearing hole and the pin crank shaft 7 supported by the rolling bearings of the support pin bearing 13 provided on the frame side and the variable crank mechanism are set as one set. Usually, the pin crank mechanism 5 which is configured by arranging it at equal intervals on the circumference of three sets is applied.

2 is a partial enlarged view of the pin crank element 6, FIG. 3 is a sectional view taken along line AA of FIG. 2, and FIG. 4 is an external view of the pin crank shaft 7.
The pin shaft bushing 8 will be described in more detail with reference to FIG.

A pin crankshaft 7 formed of an eccentric shaft 7a formed of a prism and a cylindrical support shaft 7b, a pin shaft bush 8 provided with a rectangular hole 8b in a cylinder attached to the eccentric shaft, the eccentric An elastic body 9 formed of a spring or a rubber plate mounted between the shaft and the pin shaft bush 8, and the pin shaft bush is inserted into an eccentric pin bearing fixed to the back side of the swivel scroll end plate 2a. At the same time, a plurality of pin crank elements 6 formed by inserting the support shaft 7b of the pin crank shaft into the support pin bearing 13 fixed to the frame 3 are provided on approximately the same circumference to form the pin crank mechanism 5. It

Further, during operation, the direction in which the pin shaft bush 8 moves within the eccentric shaft 7a is the direction in which the swivel shaft 4a is eccentric with respect to the main shaft of the shaft 4, that is, the direction in which the centrifugal force of the swivel scroll acts. The direction of the flat surface 7c in the eccentric shaft 7a is formed so as to be approximately the same.

One end of an elastic body 9 such as a spring is inserted and mounted in a hole 7d formed in the support shaft 7b of the pin crankshaft shown in FIG. 4, while the other end of the elastic body 9 is attached to the pin shaft of FIG. As shown in the bush 8, the bush 8 is mounted on the side where the step 8d is low such that the side inserted into the eccentric shaft provided on the wall surface in the rectangular hole 8b projects.

Thus, the eccentric shaft 7a and the pin shaft bush 8 are
Since the elastic body 9 is mounted between the pin shaft bush 8 and the pin 8, the step 8d of the pin shaft bush prevents the pin shaft bush 8 inserted from coming off the eccentric shaft 7a.

The direction in which the elastic force of the elastic body 9 which is housed in the eccentric shaft 7a and presses the pin shaft bush 8 from the inside acts also matches the moving direction of the pin shaft bush. The magnitude of the elastic force Fk is given by the following equation. Fk> 2 × R × H × (Pd−Ps) where R is the radius of the basic circle of the involute curve forming the wall surface of the working chamber, H is the height of the wall surface, and Pd and Ps are the discharge pressure, respectively. It represents the suction pressure.

However, the upper limit of Fk is 2 × R × H × (Pd−P) because it is necessary to suppress the noise and vibration due to the pressing load and to keep the efficiency within the range.
It is suitable to provide it within about 1.5 times the value of s) or less.

As another invention, a state in which the entire prism is inclined so that the outer side away from the center of the supporting shaft of the eccentric shaft escapes with respect to the rotational direction of the shaft relative to the eccentric direction of the turning shaft with respect to the main axis of the shaft. Install the pin shaft bush according to. In this case, the elastic body in the eccentric shaft may be omitted.

The inclination angle θ of the eccentric shaft is set so as to satisfy the following equation. Ft × sin θ> Fr × cos θ where Fr is the gas load in the direction opposite to the radial or centrifugal force generated by gas compression, and Ft is the direction perpendicular to the tangential or centrifugal force generated by gas compression. Represents the gas load of. The value of θ is preferably set between 5 and 20 °.

The positional accuracy of the pin crank elements, which are arranged at three positions on the circumference of each circle at approximately equal pitches, so as to mechanically connect the orbiting scroll end plate side and the frame side, is as follows. Since the degree of freedom in the eccentric direction is large, the bearing clearances and the pin crankshaft movement amounts due to the clearances may be set within the range.

When the present invention is applied to the synchronous rotation type described in Japanese Unexamined Patent Publication No. 2002-364559 in which a pair of scroll members rotate simultaneously with each other, the pin shaft bush of the pin crank mechanism has one or both sides. Provided on the scroll member. However, when it is provided on both sides, in order to ensure the stability of the pin crank shaft, it is necessary to provide the elastic body in the pin shaft bush as in the present invention.

The operation of the oil-free scroll fluid machine of the present invention constructed as described above will be described below.

Since the elastic body 9 provided in the pin crank element 6 presses the swivel scroll in the direction in which the gap between the lap side walls is reduced, the suction port 1 provided in the fixed scroll is provided.
Although the gas flowing in from d flows into the working chamber and is compressed and then flows out from the discharge port 1e, a sufficient amount of the gas is compressed and flows out from the working chamber from the initial state in which there is little leakage from the working chamber. Therefore, the rising characteristics are improved.

In an operating state in which the operation is continued and the discharge pressure reaches a predetermined value, the turning scroll accompanying the turning motion is performed.
Since the pin shaft bushing 8 can move in the centrifugal force direction along the flat surface of the eccentric shaft of the pin crank shaft 7, the centrifugal force of the pin does not act on the pin crank mechanism 5, and all the centrifugal bearing 14 and Receive at 15. Therefore, as the bearing that supports the pin crankshaft 7, a bearing having a small load bearing capacity can be used.

The load due to the gas compression acting on the swirl scroll is perpendicular to the lap wall surface of the working chamber and is a tangential force in the direction of preventing the revolution motion of the swirl scroll, a radial force in the centrifugal force direction, and the swirl scroll. -It can be decomposed into thrust force acting in the direction of separating the tip of the rule from the fixed scroll.

The tangential force is the basis of the shaft torque of the shaft and also causes the rotation moment of the orbiting scroll. The rotation moment receives the flat surface of the pin crankshaft rectangular portion 7a from the eccentric pin bearing 12 through the flat surface of the rectangular hole of the pin shaft bush 8 to prevent the rotation of the orbiting scroll from rotating.

On the other hand, the radial force acts against the centrifugal force of the orbiting scroll and the elastic force of the elastic body 9, but since the magnitude thereof is smaller than the centrifugal force or the elastic force, the pin shaft bush 8 is used.
Of the slewing bearings 14 and 1 because it acts in the movable direction of the pin crank mechanism 5 without directly acting.
You will receive it at 5.

[0048]

In the oil-free scroll fluid machine configured as described above, the pin crank mechanism is not affected by the centrifugal force of the orbiting scroll and supports only the rotation moment of the orbiting scroll. Since this is sufficient, the bearing load can be greatly reduced, and the pin crank mechanism can be made smaller and lighter and its durability can be improved.

Further, even in a region where the centrifugal force of the orbiting scroll is small such as in the low rotation speed region and at the time of starting, the elasticity provided in the pin shaft bush 8 of the pin crank element larger than the radial gas compression load Fr. Since the swivel scroll is pushed by the elastic force of the body 9 to reduce the clearance in the working chamber, there is an effect that the efficiency can be improved.

Further, by increasing the degree of freedom of the pin crank shaft in the direction of the eccentric axis by means of the pin shaft bush provided in the pin crank mechanism, the machining accuracy can be lowered and the productivity can be improved. Since it can escape, it has the effect of increasing reliability.

[Brief description of drawings]

FIG. 1 is a sectional view of a scroll fluid machine of the present invention.

FIG. 2 is a partial cross-sectional view showing an enlarged part of the pin crank mechanism of FIG.

3 is a sectional view taken along line AA of FIG.

[Figure 4] Pink rank shaft external view

[Fig. 5] Cross-sectional view of the pin shaft bush

[Explanation of symbols]

1 Fixed scroll 2 swivel scroll 3 frames 4 shafts 5 pink rank mechanism 6 pink rank elements 7 pink rank axis 7a Eccentric shaft 7b Support shaft 8-pin shaft bush 8b rectangular hole 8d step 9 elastic body 12 Eccentric pin bearing 13 Support pin bearing

Claims (2)

[Claims] 1. A scroll member A in which a spiral groove or protrusion is provided on one surface of an end plate and a spiral member of a scroll member B in which a spiral protrusion is provided on one surface of an end plate are meshed with each other. In a scroll fluid machine using a pin-crank mechanism that forms a working chamber with each other and performs a revolving motion relatively to each other between the scroll members, an eccentric shaft formed of a prism on a cylindrical supporting shaft. A pin crank shaft 7 formed by providing a pin shaft bush, a pin shaft bush 8 having a rectangular hole formed in a cylinder attached to the eccentric shaft, and a swivel scroll end plate on which the pin shaft bush is inserted. Pin crank element 6 composed of an eccentric pin bearing and a supporting pin bearing fixed to a frame into which a supporting shaft of the pin crank shaft is inserted.
2. A scroll fluid machine comprising a pin crank mechanism 5 in which a plurality of orbiting scrolls are provided between the orbiting scroll and the frame. 2. An elastic body 9 such as a spring is provided between the eccentric shaft 7a of the pink rank shaft and the wall surface of the rectangular hole of the pin shaft bush 8.
The scroll fluid machine according to claim 1, wherein a pin crank mechanism constituted by a pin crank element mounted with.