EP1674730B1

EP1674730B1 - Double-wrap scroll fluid machine

Info

Publication number: EP1674730B1
Application number: EP05078071A
Authority: EP
Inventors: Kazuaki Sato; Toru Sato
Original assignee: Anest Iwata Corp
Current assignee: Anest Iwata Corp
Priority date: 2004-12-27
Filing date: 2005-12-22
Publication date: 2012-04-11
Anticipated expiration: 2025-12-22
Also published as: EP1674730A3; JP4537846B2; KR20060074897A; KR100751769B1; EP1674730A2; JP2006183561A

Description

BACKGROUND OF THE INVENTION

The present invention relates to a scroll fluid machine such as a scroll compressor, a scroll vacuum pump, a scroll expander or a scroll blower and especially relates to a double-wrap scroll fluid machine in which an orbiting wrap of an orbiting scroll is allowed to engage with a stationary wrap of a stationary scroll to form a spiral sealed chamber between the two wraps, two fluid-pressure variable units being thus formed in a casing.
Such a double-wrap scroll fluid machine is known from DE 3 814 931 A1 , considered to represent the closest prior art. JP 2002-349456A discloses a scroll fluid machine in which an orbiting scroll is driven with the outer circumference, but in three self-rotation preventing devices, a crankshaft integrally formed with a driving shaft driven with a belt is not exactly synchronized with another crankshaft which is not driven.
There is difference in pressure between corresponding parts of spiral sealed chambers of the fluid-pressure variable units to make revolution of an end plate of an orbiting scroll tilted with respect to a surface perpendicular to an axis of a crankshaft or to cause waving.
JP 2004-116471A discloses a scroll fluid machine in which similar disadvantage to the above is involved in orbiting scrolls at both ends of an orbiting shaft which is not driven. An electric motor is disposed as driving source between right and left fluid-pressure variable units to increase its size as a whole. And if malfunction is caused in the fluid-pressure variable unit, it has to be detached with the electric motor for replacement, which is troublesome. Difference in axial load which applies to the orbiting scroll of the two fluid-pressure variable units increases loads acting onto the bearing and orbiting scroll end plate.

SUMMARY OF THE INVENTION

In view of the disadvantages, it is an object of the present invention to provide a double-wrap scroll fluid machine in which right and left fluid-pressure variable units are synchronously driven via a belt to reduce a space between the right and left fluid-pressure variable units as small as possible thereby reducing a whole size and weight, an endless belt being easily removed from a driving shaft without disassembling or detaching the fluid-pressure variable unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention will become more apparent from the following description with respect to embodiments as shown in appended drawings wherein:

Fig. 1 is a vertical sectional front view showing one embodiment of the present invention in which separate driving shafts are connected to each other with a tubular coupling;
Fig. 2 is a vertical sectional front view showing that the tubular coupling is moved from the connecting portion of the driving shafts; and
Fig. 3 is a vertical sectional front view of another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In Figs. 1 and 2, bearing tubes 3,3 projects from the opposite inner surfaces of side walls 2,2 of a housing 1. The outer ends of two coaxial separate driving shafts 5,5 fit in ball bearings 4,4 in the bearing tubes 3,3. An eccentric axial portion 6 is provided at the outer end of each of the separate driving shafts 5,5. The eccentric axial portion 6 is rotatably put in a boss 9 of an orbiting scroll end plate 8 via a roller bearing 7.
A plurality of cooling fins 10 are provided on the inner surface of the orbiting scroll end plate 8 and an orbiting wrap 11 is provided on the outer surface. The orbiting wrap 11 engages with a stationary wrap 13 which projects on a stationary scroll end plate 12 the circumference of which is fixed to the housing 1. A fluid-pressure variable unit 14 is formed on each side of the housing 1.
At three points equally spaced on the circumference of the inner surface of each of the orbiting scroll end plate 8, a receiving tube 15 is formed. In the figure, only one of them is shown. The end of a support shaft is fixed in the receiving tube 15.
A support tube 17 is provided between the side walls 2 and 2 of the housing 1 along a line between the two receiving tubes 15 and 15. In an eccentric tube 20 which is put in a thick portion 18 in the support tube 17, the support shaft 16 is rotatably supported via a bearing 21. Eccentricity of the eccentric tube 20 is equal to that of the eccentric axial portion 6 of the driving shaft 5.
The support shaft 16 plays a role of a crankshaft which can eccentrically revolve in the support shaft 17. An outward flange 22 which projects radially is formed at the opposing end faces. The outward flanges 22,22 are spaced from each other to enable an endless driving belt 23 to pass between them obliquely.
A tubular coupling 24 freely fits on the driving shaft 5 around one of the flanges 22. An annular web 27 is provided on the inner surface of a driven pulley 26 having an outer circumferential surface 25 on which the belt 23 is wound in the tubular coupling 24. The annular web 27 fits on the driving shaft 5 to allow it to contact the outer side surface of the outward flange 22.
A counter weight 28 is provided in the tubular coupling 24. The outward flanges 22, 22 facing each other with a space are connected to the annular web 27 with a screw 29.
An endless belt 23 is driven by external power to allow the orbiting scroll of the fluid-pressure variable unit 14 to revolve eccentrically, so that fluid absorbed through the outer side of the fluid-pressure variable unit 14 is pressurized towards a center.
By detaching the tightening screw 29, the tubular coupling 24 is axially moved and an opening between the facing outward flanges 22 and 22 is exposed to put the endless belt 23 into or take it out of the opening for replacement.
The driven pulley 26 may be separate from the tubular coupling 24 and may be disposed on one of the driving shafts 5.
As shown in Fig. 3, axial splines 30,31 may be provided on the inner circumference of a driven pulley 26 of a tubular coupling 24 and the outer circumference of outward flanges 22 of separate driving shafts 5,5 respectively. The spline 30 meshes with the spline 31 to assure firm coupling of drivinf shafts 5 and 5.
The foregoing merely relates to embodiments of the invention. Various modifications and changes may be made by a person skilled in the art without the scope of claims wherein:

Claims

A double-wrap scroll fluid machine comprising:
a first driving shaft having a first eccentric axial portion at an outer end;

a first orbiting scroll having a first orbiting wrap, said first orbiting scroll being rotatably mounted around the first eccentric axial portion of the first driving shaft;

a first stationary scroll having a first stationary wrap and being coaxial with the driving shaft, said first stationary wrap engaging with said first orbiting wrap to form a first spiral sealed chamber between the first stationary wrap and the first orbiting wrap;

a plurality of first self-rotation preventing devices mounted to the first orbiting scroll to prevent self-rotation of the first orbiting scroll;

a second driving shaft having a second eccentric axial portion at an outer end and being disposed to be coaxial with the first driving shaft;

a second orbiting scroll having a second orbiting wrap, said second orbiting scroll being rotatably mounted around the second eccentric axial portion of the second driving shaft;

a second stationary scroll having a second stationary wrap and being coaxial with the driving shaft, said second stationary wrap engaging with said second orbiting wrap to form a second spiral sealed chamber between the second stationary wrap and the second orbiting wrap;

a plurality of second self-rotation preventing devices mounted to the orbiting scroll to prevent self-rotation of the orbiting scroll; and

characterised in that a driving endless belt is located at the inner ends of the first and second driving shafts so that the two driving shafts can rotate together.
A double-wrap scroll fluid machine as claimed in claim 1 wherein the inner ends of the first and second driving shafts are connected to each other with a space.
A double-wrap scroll fluid machine as claimed in claim 1 wherein the inner ends of the first and second driving shafts are connected to each other with a tubular coupling.
A double-wrap scroll fluid machine as claimed in claim 3 wherein a first outward flange is formed at the inner end of the first driving shaft, a second outward flange being formed at the inner end of the second driving shaft, the first and second flanges being fixed to the tubular coupling with a screw.
A double-wrap scroll fluid machine as claimed 3 wherein the tubular coupling plays a role of a driven pulley on which the endless belt is wound.
A double-wrap scroll fluid machine as claimed in claim 3 wherein a first outward flange is formed at the inner end of the first driving shaft, a second outward flange have the same diameter as that of the first flange being formed at the inner end of the second driving shaft, a spline being formed an outer circumferences of the first and second flanges, another spline being formed on an inner circumference of the tubular coupling to mesh with the spline of the outer circumferences of the first and second flanges.