The present invention relates to a scroll fluid machine by which a high volume of gases are produced under relatively low pressure.
In a scroll fluid machine including a scroll compressor and a scroll decompressor, volume of a sealed chamber is gradually reduced from the beginning end of a wrap winding at the circumference to the terminating end near the center, so that a gas sucked from the circumference is compressed and discharged near the center or a gas sucked from the center is decompressed and discharged from the circumference.
Such a known scroll fluid machine is used for middle or high pressure to make relatively high-pressure compressed gas or achieve effective decompressing.
However, in the scroll fluid machine, to transport powders such as flour, it is impossible to obtain a high volume of compressed gases under low pressure such as about 0.2 to 0.3 MPa. To obtain a high volume of compressed gases under such low pressure, it is necessary to expand spaces between wraps and to reduce the number of windings.
Expanded spaces between the wraps make a radius of a revolving orbiting scroll larger to increase an external diameter of the orbiting scroll. So it is necessary for the heavy orbiting scroll to revolve with a larger diameter. Load adapted to a support for an orbiting shaft of the orbiting scroll increases to make it necessary to provide a high load-resistant bearing thereby resulting in increase in weight and size requiring high manufacturing cost.
To avoid such problems, the wraps must be made as close as possible to the center of the orbiting scroll not to increase a diameter of the orbiting scroll. But it involves high discharge pressure to make it impossible to obtain a desired low-pressure compressed gas.
Thus, conventionally, in a scroll compressor for low pressure, an orbiting wrap is partially removed near the center of an orbiting scroll and large-spaced wraps are provided only in parts remote from the center. However, the center of the orbiting scroll does not play a role of output, which is inefficient and uneconomical.
In view of the disadvantages in the prior art, it is an object of the present invention to provide a scroll fluid machine in which a space between wraps is the same as a known middle or high pressure machine, wraps—being provided to produce a low-pressure compressed gas almost equal to a compressed gas in the circumference to make it possible to obtain a high volume of low-pressure gases without change in the whole size or the number of revolutions of the scroll.
The features and advantages of the invention will become more apparent from the following description with respect to embodiments as shown in accompanying drawings wherein:
The scroll compressor in
In the front or left side in
A spiral stationary wrap 5 is provided on the rear surface of the stationary end plate 2. On the front surface, there are a plurality of horizontal equal-height gently-corrugated cooling fins 6 equally spaced. An orbiting scroll 7 behind the stationary scroll 1 has a spiral orbiting wrap 9 on the front surface of a circular orbiting end plate 3 or opposing surface to the stationary scroll 1, and a plurality of horizontal equal-height corrugated cooling fins 10 equally spaced on the rear surface.
On the rear surface of the orbiting scroll 7, a bearing plate 11 is mounted. At the center of the rear surface of the bearing plate 11, there is a tubular boss 15 pivotally supporting an eccentric axial portion 13 of a driving shaft 12 via a bearing 14.
At three points of the circumference on the rear surface of the bearing plate 11, there is a known crank-pin-type self-rotation preventing device 16, so that the orbiting scroll 7 is eccentrically revolved around the driving shaft 12 with respect to a housing 17.
A cover plate 18 is fixed to the front surface of the stationary scroll 1 with a screw 19. The orbiting scroll 7 is fixed to the bearing plate 11 with a screw 20. A rear portion 21 of the stationary scroll 1 is fixed to the housing 17 with a bolt 22 and a nut 23.
Engagement grooves 24,25 are formed on the tip ends of the stationary and orbiting wraps 5,9 respectively. Sealing members “S” are fitted in the engagement grooves 24,25 in sliding contact between the orbiting end plate 8 of the orbiting scroll 7 and the stationary end plate 4 of the stationary scroll 1.
As shown in
A gap between the outer volume-variable chamber stationary wrap 5a and the outer volume-variable chamber orbiting wrap 9a is large, and a gap between the inner volume-variable chamber stationary wrap 5b and the inner volume-variable chamber orbiting wrap 9b is somewhat small.
A volume ratio of an outer beginning-end volume-variable chamber “B” communicating with the outer discharger port 4a to an outer terminating-end volume-variable chamber “A” communicating with the outer intake port 3a is substantially the same as a volume ratio of an inner terminating-end volume-variable chamber “D” communicating with the inner discharge port 4b to an inner beginning-end volume-variable chamber “C” communicating with the inner intake port 3b.
Accordingly, compressed gases having almost equal pressure are produced in the outer and inner volume-variable chambers, so that a large quantity of low-pressure compressed gas is obtained compared with a conventional device in which a central wrap is removed in a scroll.
In
The foregoing merely relates to embodiments of the present invention. Various changes and modifications may be made by a person skilled in the art without departing from the scope of claims wherein.
Number | Date | Country | Kind |
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2005-25766 | Feb 2005 | JP | national |
2006-1669 | Jan 2006 | JP | national |