JPH05296163A - Scroll type fluid machine - Google Patents

Abstract

(57) [Summary] [Purpose] Overcomes the plane load Fxy based on the reaction force of the fluid confined in the working chamber V between the scrolls 1 and 2 to stably support the substrate 21 of the revolution scroll 2 and act on this substrate 21. It reduces the overturning moment and improves the sliding characteristics of each part. [Structure] An orbital groove 25 eccentric to the center O is provided on the back surface of a substrate 21 of an orbiting scroll 2, and a high pressure receiving surface 6 provided on the center side of the back surface of the substrate 21 is provided inside the groove 25 from the outer peripheral portion. While holding the eccentric circular seal ring 7 for partitioning, it is partitioned by a first straight line A passing through the revolution scroll center O and the fixed scroll center S and a second straight line B orthogonal to the straight line A and the revolution scroll center O. Among the four regions of the high pressure receiving surface 6, the first half straight line a drawn from the orbiting scroll center O to the fixed scroll center S and this half straight line a are rotated by 90 ° to the side opposite to the winding angle of the spiral body 22. The first region 61 surrounded by the second half line b is made wider than the other regions, and a pressing force that overcomes the plane load Fxy is applied to the back surface of the substrate 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scroll type fluid machine having a back pressure mechanism for pressing an orbiting scroll against a fixed scroll and used for a compressor, a vacuum pump, an expander or the like.

[0002]

2. Description of the Related Art Conventionally, as a scroll type fluid machine of this type, a scroll type fluid machine disclosed in Japanese Patent Laid-Open No. 60-224987 and shown in FIG. 3 is known.

This scroll type fluid machine is used for a compressor of a refrigerant, and inside the closed casing C,
A fixed scroll F, in which a spiral body L is erected on the front surface of the substrate K and fixed to the housing H, and a revolving scroll in which a spiral body N is erected on the front surface of the substrate M and fitted into the eccentric pin portion E of the drive shaft D. G, and a low pressure region VL in the outer peripheral portion where the suction pipe J is opened, an intermediate pressure region VM in the middle portion, and a high pressure region VH in the central portion where the discharge hole T is opened are provided between the scrolls F and G. It defines a working chamber V. Also, the revolving scroll G
The outer peripheral portion of the back surface of the substrate M is exposed to the low-pressure chamber Q communicating with the low-pressure region VL via the communication passage Z, and the central portion of the back surface of the substrate M is opened with the discharge hole T to form a high-pressure space. A high pressure chamber P communicating with the inside of the casing C via a communication passage W. An annular groove I concentric with the center O of the orbiting scroll G is provided on the rear surface of the substrate M of the orbiting scroll G, and a circular seal ring R is provided inside the groove I. On the back surface of the high pressure chamber P, a high pressure receiving surface p in the central portion facing the high pressure chamber P and a low pressure receiving surface q in the outer peripheral portion facing the low pressure chamber Q are concentrically partitioned, and the pressing force from the high pressure chamber P is revolved. It is provided at the center O of the scroll G so that the airtightness inside the working chamber V can be enhanced.

[0004]

However, in the above configuration, the seal ring R is held by the orbiting scroll G, and therefore, the high pressure chamber P is higher than that by which the seal ring R is held on the housing H side. Although the pressing force applied from the revolving scroll G can always be applied to a constant center of action regardless of the revolving angle of the revolving scroll G, the seal ring R is used for the revolving scroll G
Since it is concentric with the center O of the revolving scroll G, the center of action of the pressing force coincides with the center O of the revolution scroll G, and the pressing force is always applied to the position of this center O. In addition, the reaction force of the fluid trapped inside the working chamber V causes a rollover moment to act on the orbiting scroll G, which causes one-sided contact on the rear surface of the substrate M of the orbiting scroll G, or the drive shaft D falls and the bearing portion. There will be problems such as an increase in the load.

That is, as shown in FIG. 4, in the spiral body N of the revolving scroll G (hereinafter referred to as the revolution side spiral body), the outer surface thereof and the inner surface of the spiral body L of the fixed scroll F (hereinafter referred to as the fixed side spiral body). The first contact point h on the inner circumference where
And a wall portion connecting the inner surface of the revolution-side spiral body N and the outer contact surface of the fixed-side spiral body L to the second contact point i on the inner circumference side, the inner surface is in the high pressure region VH and the outer surface is in the intermediate pressure region VM. Since they are in contact with each other, a pressure difference is generated between these inner and outer surfaces, and the outward force f1 shown in the drawing acts. Further, in the revolution side spiral body N, the third contact point j on the outer peripheral side where the outer surface of the revolution side spiral body N contacts the inner surface of the fixed side spiral body L, and the inner surface of the revolution side spiral body N and the outer surface of the fixed side spiral body L. In the wall portion connecting the outer peripheral side fourth contact point k, the inner surface is in the intermediate pressure region VM and the outer surface is in the low pressure region V.
Since they are respectively in contact with L, a pressure difference is generated between these inner and outer surfaces, and the outward force f2 shown in the drawing acts. In addition, in the wall portion connecting the center side end e of the revolution side spiral body N and the first contact point h, both the inner and outer surfaces are in contact with the high pressure region VH,
Further, in the wall portion connecting the second contact point i and the third contact point j in the revolution side spiral body N, the inner and outer surfaces are in contact with the intermediate pressure regions VM and VM at the same pressure level, and further, the revolution side spiral body. At the wall portion connecting the fourth contact point k and the outer peripheral side end portion g in the body N, since the inner and outer surfaces are both in contact with the low pressure region VL, there is no pressure difference between these portions.

On the other hand, a straight line x1 passing through the first and third contact points h and j and a straight line x2 passing through the second and fourth contact points i and k are the center O of the revolution scroll G and the fixed scroll F. A base circle Bo having the same size that forms the revolution side spiral body N and the fixed side spiral body L with the x axis connecting the centers S of the
It will be displaced by the diameter of Bs. Therefore, at the midpoint o'between the centers O and S of the scrolls F and G, with the y axis orthogonal to the x axis as a boundary, the areas where the outward forces f1 and f2 act are the first and the second. The area on the right side in the drawing where the second and fourth contact points i, k are located is larger than the area on the left side in the drawing where the third contact point h, j is located.

Therefore, the revolving side spiral body N is a component on the y-axis that faces the wall side where a pressure difference is generated on the inner and outer surfaces thereof, and is the tangential direction of the spiral at each contact point h, i, j, k. And a tangential load Fy acting on the x-axis directed from the center O of the orbiting scroll G toward the center S of the fixed scroll F and acting in the spiral normal direction at each contact point h, i, j, k. A planar force based on the fluid reaction force composed of the normal load Fn and

Besides, since the revolution scroll G revolves around the center S of the fixed scroll F in the direction indicated by the revolution direction ω, the revolution side spiral body N revolves from the center S of the fixed scroll F. A centrifugal load Fr, which is a component on the x-axis directed to the center O side of the scroll G and is smaller in size than the normal load Fn but acts in the opposite direction, acts on the substrate M of the revolution scroll G. Means that an axial load Fz perpendicular to the plate surface acts on the basis of the fluid reaction force of the working chamber V.

Therefore, after all, the orbiting scroll G has
A total of four forces of the tangential load Fy, the normal load Fn, the centrifugal load Fr, and the axial load Fz act, and in plan view, the load Fx on the x-axis obtained by subtracting the centrifugal load Fr from the normal load Fn. And a normal load Fy on the y-axis are combined to act as a plane load Fxy, and the axial load Fxy acts in the axial direction.
z will act. The point of action of the plane load Fxy and the axial load Fz is the midpoint o'between the centers O and S of the scrolls F and G in the plane, and the height of the spiral bodies L and N in the axial direction. It is almost in the center in the vertical direction.

Thus, not only the axial load Fz but also the plane load Fxy acts on the orbiting scroll G, so that a seal ring R concentric with the center O of the orbiting scroll G is provided on the back surface of the substrate M. Even if a pressing force is applied with the center O acting as a center of action, the plane load F
The xy cannot be effectively countered, and the overturning moment acts on the substrate M, and one side region of the substrate M to which the plane load Fxy faces is pushed downward on the line of action of the plane load Fxy. A region displaced by 180 ° with respect to this region will float upward. That is, at the revolution angle position shown in FIG. 4, among the four regions divided by the x-axis and the y-axis, the region in the first quadrant on the upper right side in the figure to which the plane load Fxy is directed is the depth direction of the paper. The area in the third quadrant on the lower left side in the figure, which is pushed down by 180 ° and is displaced by 180 ° with respect to this area, floats on the front side of the drawing. As a result,
In the area pushed down, the substrate M of the revolution scroll G is
Is generated between the back surface of the scroll ring and the seal ring R, and in the floating region, a partial contact is generated between the scroll N and the substrate K of the fixed scroll F, and the substrate M is driven by overturning. This causes the problem that the shaft D falls and the load of the bearing portion supporting the shaft D increases.

In particular, this problem remarkably appears under a low differential pressure operation condition in which the high pressure decreases and the difference from the low pressure decreases, and the pressing force from the high pressure chamber P relatively decreases.

In this case, it is conceivable to increase the diameter of the seal ring R to increase the pressing force from the high pressure chamber P. In this case, however, the center O of the orbiting scroll G is too large from the rear surface thereof. Only a pressing force is applied in the axial direction, and a sliding loss unnecessarily increases, which causes a problem of reducing reliability.

The object of the present invention is to overcome the flat load due to the reaction force of the fluid trapped in the working chamber, to stably support the substrate of the revolution scroll, and to reduce the overturning moment acting on the revolution scroll, An object of the present invention is to provide a scroll-type fluid machine that can suppress a one-sided contact and an increase in bearing load in a moving part and can perform a smooth sliding operation.

[0014]

In order to achieve the above object, therefore, a fixed scroll 1 in which a spiral body 12 is erected on the front surface of a substrate 11 and an orbiting scroll 2 in which a spiral body 22 is erected on the front surface of a substrate 21. And the central part of the rear surface of the substrate 21 in the orbiting scroll 2,
In the scroll type fluid machine facing the high pressure chamber 4 which has a high pressure with respect to the base plate 2 in the revolution scroll 2.
A seal ring 7 for partitioning between a low pressure receiving surface 5 facing the low pressure chamber 3 and a high pressure receiving surface 6 facing the high pressure chamber 4 is held on the rear surface of 1, and the center O of the revolution scroll 2 and the fixing First straight line A passing through the center S of the scroll 1
Of the first to fourth regions of the high-pressure pressure receiving surface 6 which are divided into four by the first straight line A and the second straight line B orthogonal to the center O of the orbiting scroll 2.
Of the first half straight line a drawn from the center O to the center S of the fixed scroll 1 and the first half straight line a rotated by 90 ° to the side opposite to the winding angle of the spiral body 22 in the revolution scroll 2. The first region surrounded by the two half-lines b is wider than the other second to fourth regions.

Further, in the above structure, for simplification of the structure, the seal ring 7 is centered in the first region of the high-pressure pressure receiving surface 6 and is a circular ring eccentric to the center O of the revolution scroll 2. 71 is preferable.

[0016]

By widening the first region of the high-pressure pressure receiving surface 6 defined by the seal ring 7 with respect to the other regions, the scroll 1, the scroll 1,
A pressing force that overcomes the plane load based on the reaction force of the fluid trapped between the two can be applied, and the orbiting scroll 2
It is possible to reduce the overturning moment that acts on the base plate 21 and to maintain good parallelism of the base plate 21 of the revolution scroll 2.

The circular ring 71 is used to seal the seal ring 7.
With the above configuration, the first region can be made wider than other regions with a simple configuration, and the configuration can be simplified.

[0018]

EXAMPLE A scroll type fluid machine shown in FIG. 2 is used as a compressor for a refrigerant in a refrigerating machine, and has an upper housing inside a hermetic casing 8 having a body 81, an upper lid 82 and a lower lid 83. 84 and the lower housing 85 are fixed, and these housings 84 and 85 are used as supporting members, and the substrate 1 is placed at a position above the inside of the casing 8.
Spiral body 12 along the involute shape on the lower front part of 1
And a fixed scroll 1 in which the outer peripheral wall 13 is fixed to the upper housing 84, and a spiral body 22 that also follows the involute shape on the upper front surface of the substrate 21, and the drive shaft 9 is attached to the boss cylinder 23 on the rear surface. The eccentric pin portion 91 is fitted and the revolution scroll 2 whose rotation is prevented by the Oldham ring 20 is arranged, and a motor 90 having the drive shaft 9 directly connected to a lower position inside the casing 8. It is arranged.

Then, between the scrolls 1 and 2,
From the low pressure region VL of the outer peripheral portion where the suction pipe 86 for guiding the low pressure fluid is opened to the intermediate pressure region VM of the intermediate portion and the high pressure region VH of the central portion
A discharge hole 1 which defines a working chamber V having a pressure gradient in succession and which opens a high-pressure fluid at the center of the fixed scroll 1.
4 through the internal space 80 of the casing 8 to the discharge pipe 8
I take it out from 7.

Further, the outer peripheral surface of the rear surface of the substrate 21 in the revolution scroll 2 is exposed to the low pressure chamber 3 communicating with the low pressure region VL through the communication passage 15, and the central portion of the rear surface of the substrate 21 is adjusted to the inside. The high-pressure chamber 4 communicated with the space 80 through the communication passage 88 also serving as an oil drain hole is faced, and the revolving scroll 2 is pressed against the fixed scroll 1 by the pressing force applied from the high-pressure chamber 4, so that the working chamber V I try to improve the airtightness.

An oil sump 89 for accumulating lubricating oil is provided at the bottom of the casing 8, and the oil in this oil sump 89 is
Oil pickup 9 attached to the lower end of the drive shaft 9
Through 2 to the oil supply passage 93 provided inside the shaft,
Lower main bearing 94, upper main bearing 95, and pin bearing 9
I am trying to refuel 6th grade.

In the above structure, an annular groove 25 is provided on the rear surface of the base plate 21 in the revolution scroll 2, and the groove 25 has a low pressure receiving surface 5 facing the low pressure chamber 3 and a high pressure receiving surface facing the high pressure chamber 4. The seal ring 7 that separates from the surface 6 is held together with the auxiliary biasing means 70 formed of an O-ring.

In this case, as clearly shown in FIG. 1, the center circle of the revolution scroll 2, that is, the basic circle Bo of the involute constituting the spiral body 22 of the revolution scroll 2.
A first straight line A passing through the center O of the fixed scroll 1 and the center S of the basic circle Bs of the involute that constitutes the spiral body 12 of the fixed scroll 1;
The first region 61 to the high pressure receiving surface 6 divided into four by the straight line A and the second straight line B orthogonal to the center O of the revolution scroll 2
In the fourth region 64, a first half line a drawn from the center O of the orbiting scroll 2 to the center S of the fixed scroll 1 and this first half line a is the anti-progression of the winding angle of the spiral body 22 in the orbiting scroll 2. Side, that is, the revolution direction ω of the revolution scroll 2
The first region 61 surrounded by the second half line b rotated by 90 ° in the same direction as is wider than the other second region 62, the third region 63, and the fourth region 64.

Specifically, the first area 61 is replaced with another area 6
In order to make it wider than 2, 63, 64, the seal ring 7 is a circular ring 71 having a center Op in the first region 61 of the high pressure receiving surface 6 and eccentric to the center O of the revolution scroll 2. Make up.

Thus, with the above structure, a pressing force that overcomes the plane load Fxy based on the reaction force of the fluid trapped in the working chamber V can be applied to the back surface of the substrate 21 in the revolution scroll 2, and the revolution scroll 2 Board 2
It is possible to reduce the overturning moment acting on 1 and maintain the parallelism of the substrate 21 of the revolution scroll 2 in a good condition.

The circular ring 71 is used as the seal ring 7.
By configuring the first region 61 with a simple configuration
Can be made wider than other areas, and the configuration can be simplified.

However, except that the seal ring 7 is composed of such a circular ring 71, the protrusion of the peripheral edge of the high-pressure pressure receiving surface 6 to the first region 61 is made larger than the protrusion of the peripheral edge to other regions, for example. It may be configured by a non-circular ring having an elliptical shape or the like.

Although the above-mentioned embodiment shows an example of application to a compressor, it can be applied to a vacuum pump in exactly the same manner.
It can also be applied to an expander. However, when used in an expander, the flow of fluid is opposite to that in the case of using a compressor or a vacuum pump, so the discharge pipe 87 serves as a high-pressure fluid introduction pipe and the suction pipe 86 discharges low-pressure fluid. In the case of a pipe, and in the compressor or the vacuum pump, the counterclockwise direction in FIG. 1 is the revolution direction, whereas the opposite clockwise direction is the revolution direction.

[0029]

According to the invention as set forth in claim 1, each of the scrolls 1, 2
A pressing force that overcomes the plane load based on the reaction force of the fluid trapped between the two can be applied, and the orbiting scroll 2
It is possible to reduce the overturning moment that acts on the base plate 21 and to maintain good parallelism of the base plate 21 of the orbiting scroll 2, thereby suppressing an uneven contact and an increase in bearing load in the sliding portion. Therefore, a smooth sliding operation can be performed.

According to the second aspect of the present invention, since the seal ring 7 is composed of the circular ring 71, the structure can be simplified.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a meshing state of a fixed scroll and an orbiting scroll according to a scroll type fluid machine of the present invention.

FIG. 2 is a vertical cross-sectional view showing the overall structure of the scroll type fluid machine.

FIG. 3 is a partial vertical sectional view of a conventional scroll type fluid machine.

FIG. 4 is a cross-sectional view showing a meshed state of a first scroll and a second scroll for explaining a conventional problem.

[Explanation of symbols]

1; fixed scroll, 11; substrate, 12; spiral body, 2;
Orbiting scroll, 21; substrate, 22; spiral body, 3; low pressure chamber, 4; high pressure chamber, 5; low pressure receiving surface, 6; high pressure receiving surface, 6
1; first area, 62; second area, 63; third area, 6
4; fourth region, 7; seal ring, 71; circular ring

Claims (2)

[Claims] 1. A fixed scroll 1 in which a spiral body 12 is erected on a front surface of a substrate 11, and an orbiting scroll 2 in which a spiral body 22 is erected on a front surface of a substrate 21.
In the scroll type fluid machine in which the center of the back surface of the substrate 21 in the above is faced to the high pressure chamber 4 which has a higher pressure than the low pressure chamber 3 in the outer periphery of the back surface, the low pressure chamber 3 is provided on the back surface of the substrate 21 in the revolution scroll 2. The seal ring 7 for partitioning the low pressure receiving surface 5 facing the high pressure chamber 4 and the high pressure receiving surface 6 facing the high pressure chamber 4, and passing through the center O of the revolution scroll 2 and the center S of the fixed scroll 1. 1 straight line A, the first straight line A and the center O of the revolution scroll 2
The high-pressure receiving surface 6 divided into four by the second straight line B orthogonal to
Of the first to fourth regions, the first half line a drawn from the center O of the orbiting scroll 2 to the center S of the fixed scroll 1 and the first half line a are the spirals 22 in the orbiting scroll 2. A scroll type fluid machine characterized in that a first region surrounded by a second half line b rotated by 90 ° on the side opposite to the winding angle of is wider than the other second to fourth regions. .. 2. The seal ring 7 comprises the high pressure receiving surface 6
The orbiting scroll 2 having a center in the first region in
The scroll type fluid machine according to claim 1, wherein the scroll type fluid machine comprises a circular ring 71 eccentric with respect to the center O.