1. Field of the Invention
The present invention relates to a fluid agitation apparatus for reducing temperature fluctuation, and a thermostatic apparatus using the fluid agitation apparatus.
2. Description of the Related Art
In recent years, there has been required nanometer-order positioning and processing accuracy for semiconductor exposure apparatuses and ultra-precision machining apparatuses, and along with this, there has been required temperature stability of the apparatus at a tolerance of ±0.001° C.
In order to stabilize the temperature of the apparatus at a constant temperature, a thermostatic chamber is generally prepared to circulate air controlled at a constant temperature. However, even when the temperature of the gas (for example, air) introduced into the thermostatic chamber fluctuates, the temperature of the thermostatic chamber fluctuates, which may reduce the temperature stability of the apparatus.
In order to reduce such temperature fluctuation, there has been proposed a fluid agitation apparatus capable of reducing temperature fluctuation of a fluid in a cross section on a downstream side of a fluid passage. Examples of the conventional fluid agitation apparatus include a fluid agitation apparatus for agitating a fluid through use of a movable member such as a propeller, and as exemplified in
In the conventional fluid agitation apparatus using the movable member as described above, there has been a problem that the temperature may still fluctuate due to heat generated in a sliding portion of the movable member. Further, in the conventional fluid agitation apparatus using the fluid passage processed into a spiral shape as exemplified in
It is an object of the present invention to attain a fluid agitation apparatus using a structure which is simple in shape and short in a fluid passage direction without a movable part so as to produce a sufficient effect from the viewpoint of reducing temperature fluctuation, and to propose a thermostatic apparatus capable of reducing temperature fluctuation thereof.
According to an exemplary embodiment of the present invention, there is provided a fluid agitation apparatus for reducing temperature fluctuation, including, in an order from an upstream side thereof: a dividing part for dividing a flow of a fluid into a plurality of flows; a circumvolving part for circumvolving the fluid about an axis in a flow direction of the fluid; and an accelerating part for increasing a flow rate of the fluid.
According to an exemplary embodiment of the present invention, there is provided a thermostatic apparatus, including the above-mentioned fluid agitation apparatus for reducing temperature fluctuation.
According to the present invention, the fluid is divided into a plurality of flows by the dividing part, and the plurality of flows are mixed again by generating circumvolving flows about the axis in the flow direction during a period in which the flows pass through the circumvolving part. The mixed circumvolving flows are accelerated by the accelerating part into stronger circumvolving flows so that the fluid is sufficiently agitated. As a result, the temperature fluctuation of the fluid can be reduced and therefore the temperature fluctuation in the thermostatic chamber can be suppressed.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
A fluid agitation apparatus for reducing temperature fluctuation according to the present invention includes, in an order from an upstream side thereof, a dividing part for dividing a flow of a fluid into a plurality of flows, a circumvolving part for circumvolving the fluid about an axis in a flow direction of the fluid, and an accelerating part for increasing a flow rate of the fluid. Accordingly, it is possible to attain a fluid agitation apparatus which provides a sufficient effect from the viewpoint of reducing temperature fluctuation.
In the following, with reference to the attached drawings, exemplary embodiments of the present invention are described in more detail by way of examples. However, the present invention is not limited to the following embodiments.
A fluid agitation apparatus 11 for reducing temperature fluctuation according to the first embodiment is installed in the fluid passage with its dividing part 12 side set as the upstream side. The dividing part 12 is closed by a closing surface 121 at a part in the vicinity of a center of the fluid passage, and hence the fluid in the fluid passage cannot pass through this region, but instead passes through a region of arcuate opening planes 122 provided at two opposing locations in the vicinity of an outer periphery of the fluid passage.
A circumvolving part 13 connects the dividing part 12 and an accelerating part 14 to each other. As indicated by the cross hatching of
In this embodiment, in order to generate circumvolving flows more effectively in the circumvolving part 13, stationary surfaces 132 having a rectangular plate shape are arranged in the fluid passage of the circumvolving part 13 in a direction parallel to the fluid passage direction. One end of each stationary surface 132 is held in contact with an inner peripheral wall of the circumvolving part 13 so that the circumvolving flow is generated only in one direction (direction indicated by the arrow in
The circumvolving flows generated by the mechanism as described above are accelerated into stronger circumvolving flows by passing through the opening plane 141 of the accelerating part 14, which has an area smaller than a sectional area of the circumvolving part 13 in a direction perpendicular to the fluid passage direction.
In this embodiment, the cross sections of the opening plane 141 of the accelerating part 14 and the fluid passage continuous with the downstream side thereof are formed into a circular shape. Therefore, the circumvolving flows are formed into a spiral shape, and fluid stagnation points are not easily generated on the downstream side of the accelerating part 14. Accordingly, the fluid is sufficiently agitated, with the result that the temperature fluctuation of the fluid can be reduced.
A numerical analysis was conducted to compare an effect of reducing temperature fluctuation of the fluid according to this embodiment with an effect of reducing temperature fluctuation of the fluid according to an example of a conventional fluid agitation apparatus. In the following, conditions and results of the analysis are described.
In the numerical analysis conducted in this case, it is assumed that the fluid flows from the left to the right in
As can be seen from
Further, regarding the status of the temperature fluctuation imparted as an initial condition of the numerical analysis, a temperature difference of 10° C. at maximum is imparted at the temperature fluctuation imparting surface, which is common between the both examples.
In the fluid agitation apparatus according to the example of the present invention illustrated in
Besides the above-mentioned conditions, the types of fluid and the like were changed so that the numerical analysis was conducted under a plurality of conditions. Table 1 shows the conditions and results of the numerical analysis in combination.
As can be seen from the results of the numerical analysis shown in Table 1, the fluid agitation apparatus according to the example of the present invention exhibits a higher degree in the effect of reducing temperature fluctuation of both air and water as compared to the example of the conventional fluid agitation apparatus. Further, as described above, the overall length of the fluid agitation apparatus according to the example of the present invention is 500 mm, whereas the overall length of the fluid agitation apparatus according to the conventional example is 1,200 mm. It can be said from the above that the fluid agitation apparatus according to the example of the present invention is simpler in shape and short in the fluid passage direction, and exhibits a higher degree in the effect of reducing temperature fluctuation of both air and water as compared to the example of the conventional fluid agitation apparatus.
A fluid agitation apparatus 21 for reducing temperature fluctuation according to the second embodiment is different from the fluid agitation apparatus 11 for reducing temperature fluctuation according to the first embodiment in that a circumvolving part 23 has a rectangular outline. Along with this, the shapes of a dividing part 22 (opening planes 222 have a polygonal shape) and stationary surfaces 232 (wedge shape) are different from those of the first embodiment. However, the functions attained by the dividing part 22, the circumvolving part 23, and an accelerating part 24 are the same as those of the corresponding components of the first embodiment. When the main part of the fluid passage is desired to have a rectangular shape in cross section from the viewpoint of installation, the fluid agitation apparatus is formed into the shape as described in this embodiment, with the result that the same performance as that of the fluid agitation apparatus of the first embodiment can be obtained.
The functions of the respective components of the fluid agitation apparatus 21 according to the second embodiment are the same as those of the corresponding components of the first embodiment, and detailed description thereof is therefore omitted herein.
Incidentally, there have herein been described only two embodiments in which the fluid agitation apparatus has a circular or rectangular outline, but the fluid agitation apparatus may have a triangular, pentagonal, or other polygonal outline, and may have a shape obtained by combining curved lines and straight lines instead. Further, there has only been described that the dividing part divides the flow of the fluid into two flows, but the dividing part may divide the flow of the fluid into three or more flows.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2011-267064, filed Dec. 6, 2011 which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
---|---|---|---|
2011-267064 | Dec 2011 | JP | national |