JP2780233B2 - Scroll compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improvement in the shape of the central portion of a movable scroll in a variable displacement scroll compressor that enables a partial load operation with a small capacity for full load operation. About.

(Prior Art) Conventionally, as known in Japanese Patent Application Laid-Open No. 61-291792, this type of compressor has a discharge valve attached to a discharge hole and opens a compression chamber in the middle of compression to a suction side. Thus, a partial load operation having a lower capacity than that of the full load operation can be performed.

Also disclosed in JP-A-62-118082 and the fifth
As shown in the figure, when the movable scroll (OS) is turned, the innermost peripheral contact point (Q) between the inner surface (Fa) of the fixed spiral and the outer surface (Ob) of the movable spiral starts the winding of the fixed scroll (FS). Corner (U1)
When it reaches an angle (θs = U1 + π) that is extended by about half a circle from, the compression operation to the design pressure ratio is completed, and the tip (X) of the movable scroll moves from the inner surface (Fa) of the fixed spiral to the movable spiral. The inner surface (Oa) is apart from the tip (Y) of the fixed scroll, and the outer surface (Ob) of the movable scroll and the inner surface (F
a) and the compression chamber (B) defined by the inner surface (Oa) of the movable vortex and the outer surface (Fb) of the fixed vortex. It communicates with the discharge hole (H) via Y). As described above, the shape of the central portion of each of the spiral inner surfaces (Fa) and (Oa) at which the tip portions (X) and (Y) are separated from each other and the discharge starts, ensures that each of the compression chambers (A And (b) approximating it with a large arc that sufficiently secures the gas flow area from (B).

In FIG. 5, (G) is the base circle of the involute constituting the movable spiral, and (G ') is the same base circle constituting the fixed spiral.

(Problems to be Solved by the Invention) By the way, in the above configuration, the outer surface (O
As soon as the compression chamber (A) defined by b) and the inner surface (Fa) of the fixed spiral is communicated with the discharge hole (H) through the tip (X) of the orbiting scroll (OS), the movable chamber becomes movable. The outer surface (Ob) of the spiral reaches the edge (e) of the discharge hole (H), and most of the gas in the compression chamber (A) flows directly into the discharge hole (H). For this reason, the gas flow passing through the gap between the tip (X) of the orbiting scroll and the inner surface (Fa) of the fixed spiral has a small effect on the throttle effect received from the gap. On the other hand, almost all of the gas in the compression chamber (B) defined by the inner surface (Oa) of the movable scroll and the outer surface (Fb) of the fixed spiral is substantially equal to the tip (Y) of the fixed scroll and the movable scroll. Since the gas flow from the compression chamber (B) passes through the gap with the inner surface (Oa), the effect of the throttle effect on the gas flow when passing through the gap is large. Thus, in the above conventional example,
From the viewpoint of ensuring a gas flow with low resistance, the central portion of the inner surface (Oa) of the movable spiral is formed in a shape that ensures a large gas flow area.

However, the above configuration is not advantageous for a compressor capable of partial load operation, and has a problem that a loud seating sound is generated by a discharge valve during partial load operation, which causes noise, as described in detail below. .

FIG. 6 shows the pressure change of the compression chamber with respect to the rotation angle of the orbiting scroll (OS). The solid line shows the full load operation, the dotted line shows the partial load operation, and the chain line shows the discharge pressure. . Thus, when the movable scroll (OS) passes through the angle (θs) shown in FIG. 5, each of the compression chambers (A) and (B) communicates with the discharge hole (H). Compression chamber (B) as well as chamber (A)
Also, since the space between the inner surface (Oa) of the movable scroll and the tip (Y) of the fixed scroll is widely secured, the pressure on the push-up side of the discharge valve immediately becomes equal to the pressure of each compression chamber (A) (B). As a result, the pressure difference (ΔP1) (ΔP2) occurs before and after the discharge valve in each of the full load and partial load operations. At this time, especially during the partial load operation, each compression chamber (A)
Since the pressure of (B) is low, a large pressure difference (ΔP1) is generated. Therefore, the discharge valve which has been opened until the angle (θs) is reached, after the angle (θs), the large pressure difference (ΔP1) When the discharge valve is seated on the valve seat portion surrounding the discharge hole (H), a loud noise is generated, and the impact force at the time of the seating reduces the reliability of the valve. It happens.

In the present invention, attention is paid to the gas flowing portion from the compression chamber side defined by the inner surface of the movable spiral and the outer surface of the fixed spiral through which almost all of the gas passes, and the shape of the flowing portion is devised. Accordingly, it is an object of the present invention to provide a scroll compressor which can reduce the seating noise of the discharge valve mainly at the time of partial load.

(Means for Solving the Problems) Therefore, in the present invention, in order to achieve the above object, the fixed spiral and the movable spiral (22) (32) along the involute curve from the center to the outer periphery of the end plates (21) and (31). ) Are provided with fixed and movable scrolls (2) and (3), respectively, and a discharge valve (12) is attached to a discharge hole (11) provided at the center of the fixed scroll (2), and a compression chamber being compressed. In the scroll type compressor in which the partial load operation is performed by opening the suction to the suction side, the inner surface (3
In (a), the center of the involute (T) passing through the innermost contact point (P) between the inner surface (3a) of the movable spiral and the outer surface (2b) of the fixed spiral in the state of being compressed to the design pressure ratio is centered ( O), the movable scroll (3) in a state in which the radius (Rtrim) is larger than the base circular diameter (2Rg) of the involute, and the movable scroll (3) is advanced by 120 ° from a state compressed to a design pressure ratio. The communication area secured in the gap with the tip of the fixed scroll (2) is about the maximum communication area.
The innermost side of the arc (S) smaller than the diameter (Re) at which the aperture ratio becomes 30%, and the outer surface (3b) of the movable vortex and the inner surface (2a) of the fixed vortex when compressed to the design pressure ratio A compression chamber (B) having an inner contour consisting of a tangent (L) drawn from the contact point (Q) to the arc (S), and defined by an inner surface (3a) of a movable spiral and an outer surface (2b) of a fixed spiral. ), A built-up portion (30) for giving a predetermined resistance to the flow of the gas flowing from the discharge hole (11) side was formed.

(Function) The discharge hole (1) is formed in the compression chamber (B) by the overlay portion (30).
1) Resistance to the flow of gas flowing from the side can be given, the pressure drop speed on the push-up side of the discharge valve (12) can be slowed, and the valve speed when the discharge valve (12) is seated can be reduced. In particular, since the radius (Rtrim) of the arc (S) of the built-up portion (30) is smaller than the diameter (Re), a large differential pressure before and after the discharge valve (12) during partial load operation. When the discharge valve (12) is about to close suddenly, sufficient resistance is given to the flow of gas flowing backward from the discharge valve (12) side, and the valve closing speed can be sufficiently reduced. As described above, the radius (Rtrim) of the arc (S) is made larger than the base circular diameter (2Rg) of the involute, although the opening ratio of the passage is reduced in order to reduce the valve closing speed. Can be prevented from significantly lowering.

(Example) FIG. 2 shows a fixed spiral and a movable spiral (22) (32) on an upper part of a closed casing (1) along an involute curve from the center to the outer periphery of the end plates (21, 31).
The fixed and movable scrolls (2) and (3), each of which protrudes, are supported via a frame (4), and a discharge valve (12) is attached to a discharge hole (11) provided at the center of the fixed scroll (2). Then, the orbiting of the movable scroll (3) causes the low-pressure gas sucked from the suction chambers (13) and (13) to flow into each of the spirals (22) and (3).
2) Compression in two systems of compression chambers (A) and (B) formed between them, and high-pressure gas is discharged from discharge hole (11) to discharge chamber (14).
Through the discharge pipe (15).

The fixed scroll (2) has a pair of unloader cylinders (2) corresponding to the two systems of compression chambers (A) and (B).
3) (only one is shown) is protruding and the cylinder (2
An unloader piston (5), which is urged to the open side by a spring (24), is mounted on 3), and the compression chambers (A) and (B) open to the piston advance side of the piston (5) during the compression stroke. A bypass hole (26) is formed. Then, the operating pressure introducing pipe joint (71) is inserted into the back pressure chamber (25) of the cylinder (23).
By introducing a high operating pressure through a passage means (10) consisting of a connection joint (7), a straight pipe (9) and a distribution joint (8), the bypass hole (26) is closed and full load operation is performed. or,
By introducing a low operating pressure through the passage means (10), the bypass hole (26) is opened to the suction chamber (13) through the communication path (27) to perform a partial load operation. .

In FIG. 2, (167) is a valve retainer, and (18) is an oil separator.

In the above configuration, as shown in FIG. 1, the inner surface (3a) of the movable vortex and the outer surface of the fixed vortex in the illustrated state compressed to the design pressure ratio are formed on the inner surface (3a) at the center of the movable vortex (32). An arc (S) having a center (O) on the normal (T) of the involute passing through the innermost peripheral contact point (P) with (2b);
In the state shown in the drawing, the outer surface (3b) of the movable spiral and the inner surface (2a) of the fixed spiral have an inner contour consisting of a contact (L) drawn from the innermost peripheral contact (Q) to the arc (S). ,
A built-up portion (10) for providing a predetermined resistance to the flow of gas flowing from the discharge hole (11) into the compression chamber (B) defined by the inner surface (3a) of the movable spiral and the outer surface (2b) of the fixed spiral. Form 30).

Specifically, the radius (Rtrim) of the arc (S), which determines the size of the build-up portion (30) and thus the gas flow resistance from the discharge hole (11) side to the compression chamber (B). Range
As shown in FIG. 3, the valve speed is set in a range where the valve speed at the time of sitting can be reduced without lowering the performance (EER ratio). That is,
This radius (Rtrim) is necessary to reduce the valve speed.
The movable scroll (3) is displaced from the state shown in FIG.
During the advance of about 120 ° shown in FIG. 2B through FIG. 2A, the tip (Y) of the overlay (30) and the fixed scroll (2).
Fig. 4 (c) shows the communication area secured in the gap (δ) between
The diameter is set to be smaller than the diameter (Re) that provides an opening ratio of about 30% with respect to the communication area when the gap (δmax) is widened by about 180 ° as shown in the figure. It is set to be larger than the diameter (2Rg) of (G).
That is, the radius (Rtrim) is set in the range of 2Rg <Rtrim <Re. In FIG. 3, (π
Rg-t / 2t; spiral width) is a diameter when the shape is approximately similar to an involute curve shown by a two-dot chain line in FIG.

According to the above configuration, a predetermined resistance can be given to the flow of the gas flowing into the compression chamber (B) from the discharge hole (11) side, and the pressure of the discharge valve (12) can be increased without lowering the performance. Can be slowed down, and the valve speed when the discharge valve (12) is seated can be reduced.

The inner surface of the center of the spiral is defined by the arc (S) and the tangent (L).
Thus, since the corners are eliminated, the stress concentration can be reduced and the strength can be improved.

In the embodiment shown in FIG. 1, the fixed scroll (2) also has the same inner contour consisting of the arc (S ') and the tangent (L') as described above, and the radius of the arc (Rtrim ')
Are provided in the same manner as described above, and the spiral shape of the two scrolls is the same. But,
In the present invention, the overlay portion (30) may be provided at least only in the movable scroll (3).

(Effects of the Invention) As described above, in the present invention, since the built-up portion (30) is provided, the discharge hole is formed in the compression chamber (B) defined by the inner surface (3a) of the movable spiral and the outer surface (2b) of the fixed spiral. Resistance can be given to the flow of gas flowing in from the (11) side, the pressure drop on the push-up side of the discharge valve (12) can be slowed, and the valve speed when the discharge valve (12) is seated can be reduced. In addition to suppressing the sound when the discharge valve is seated during the partial load operation, the reliability of the discharge valve (12) can be improved by reducing the impact force, and thus, the valve closing speed can be reduced. Even though the opening ratio of the passage is narrowed, the EER can be prevented from being greatly reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of a scroll type compressor of the present invention, and FIG.
Fig. 3 is a vertical cross-sectional view of the compressor, partly omitted. Fig. 3 is a view for explaining a setting range of a radius of an arc. Figs. FIG. 5 is a plan view showing the displacement of the scroll in order, FIG.
The figure shows the state of the compression chamber when performing full load and partial load. (2) ... fixed scroll (3) ... movable scroll (21) (31) ... mirror plate (22) ... fixed spiral (32) ... movable spiral (2a) (3a) ... inner surface (2b) ( 3b) Outer surface (11) Discharge hole (12) Discharge valve

────────────────────────────────────────────────── ─── Continuing on the front page Judge Masatoshi Koike, Judge, Judge Eiaki Kiyota Judge, Nobuyuki Shimizu (56) References JP-A-61-291792 (JP, A) JP-A-64-56981 (JP, A) 59-58187 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F04C 18/02 311 V

Claims (1)

(57) [Claims] 1. A fixed spiral and a movable spiral (2) extending along the involute curve from the center to the outer periphery of the end plates (21) and (31).
2) A fixed and movable scroll (2) and (3), each of which protrudes (32), is provided with a discharge valve (12) at a discharge hole (11) provided at the center of the fixed scroll (2),
In the scroll type compressor in which the compression chamber in the middle of compression is opened to the suction side to perform the partial load operation, the inner surface (3a) at the center of the movable spiral has the inner surface of the movable spiral compressed to a design pressure ratio. The center (O) is located on the normal (T) of the involute passing through the innermost contact point (P) between the (3a) and the outer surface (2b) of the fixed spiral, and the radius (Rtrim) is the base circle diameter of the involute (Rtrim). 2Rg) and the movable scroll (3) from the state compressed to the design pressure ratio
The communication area secured in the gap between the orbiting scroll (3) and the distal end of the fixed scroll (2) in the state advanced by 120 ° is larger than the diameter (Re) at which the opening ratio is about 30% of the maximum communication area. Smaller arc (S), outer surface of movable vortex (3b) and inner surface of fixed vortex (2a) when compressed to design pressure ratio
And a tangent line (L) drawn from the innermost peripheral contact point (Q) to the arc (S), and is defined by an inner surface (3a) of the movable spiral and an outer surface (2b) of the fixed spiral. A scroll type compressor having a built-up portion (30) for giving a predetermined resistance to the flow of gas flowing from the discharge hole (11) side into the compression chamber (B) to be formed.