JPH0451301Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a constant air volume device, more specifically, to a constant air volume device that maintains a predetermined air volume even if the pressure on the upstream side of an air conditioning duct fluctuates. be.

(Prior Art) Conventionally, as one type of air conditioning system, there is a system called a fan coil unit or a small package system. In both of these systems, a large number of small air conditioning units are distributed in the ceiling and each is operated independently. In order to supply outside air to each air conditioning unit, a method has generally been used in which dust is removed and the outside air is cooled or heated using an outside air conditioner, and then the air is supplied to each air conditioning unit through an outside air duct.

(Problem that the invention aims to solve) However, since the amount of outside air supplied to each air conditioning unit is small compared to the amount of circulating air conditioned air supplied into the room, the outside air duct has a small diameter, and the duct Since it is long in relation to its diameter and has many branches, it is difficult to adjust the amount of outside air supplied to each air conditioning unit.

Conventionally, when adjusting the amount of outside air, a damper for adjusting the air volume is attached to each air conditioning unit, but adjusting the damper opening at one location affects other locations, so the number of air conditioning units is Because of the large number of air conditioners, ensuring the required amount of outside air for each air conditioning unit required a great deal of effort and was problematic.

The present invention was developed in view of the above-mentioned circumstances, and its purpose is to eliminate the need for adjustment after installation in the duct, and to maintain the air volume at the specified air volume even if the upstream pressure fluctuates. The aim is to provide a constant air volume device that closes the air.

(Means for Solving the Problems) In order to achieve the above object, the constant air volume device according to the present invention includes an outer cylinder for forming an outer shell, and an outer cylinder disposed within the outer cylinder with a gap between the outer cylinder and the outer cylinder. Along with being equipped with
an inner cylinder in which a downstream end of the gap is closed and a cylinder wall is formed with a flow passage opening for communication between the upstream side and the downstream side; A wind pressure receiving plate whose outer peripheral edge slides in sliding contact with the inner wall surface of the inner cylinder is movably supported by the wind pressure receiving plate guide rod, and the wind pressure receiving plate is stopped on the downstream side of the wind pressure receiving plate in equilibrium with the wind pressure. A valve body portion is provided with a balancing spring to move a wind pressure receiving plate in response to wind pressure on the upstream side, and to change an area provided for communication between the upstream side and the downstream side of the flow path opening. Become,
The opening forming curve that forms the flow path opening is expressed by the following formula: y=k ₁ (x+k ₂ ) ^-3/2 where x: length of the opening in the axial direction of the inner cylinder y: inner cylinder The length of the opening in the circumferential direction k ₁ , k ₂ : is a hyperbola that satisfies constants.

(Function) Since the constant air volume device according to the present invention is configured as described above, when this constant air volume device is inserted and connected in the middle of an air conditioning duct, the wind pressure receiving plate is moved by the balancing spring before the ventilation starts. The area provided for communication between the upstream side and the downstream side of the channel opening is maximized.

Next, when ventilating the upstream side of the constant air volume device, the ventilated air enters the gap between the outer cylinder and the inner cylinder, and then the upstream side and downstream side of the flow path opening communicate with each other. It enters the inner cylinder through the communicating part and flows out to the downstream side. At this time, when the wind pressure that the wind pressure receiving plate receives becomes larger than the reaction force of the balancing spring, the wind pressure receiving board is moved downstream by the wind pressure and is stopped at a position where the wind pressure and the reaction force of the balancing spring are balanced. . As the pressure on the upstream side increases, the distance the wind pressure receiving plate moves toward the downstream side increases, so the area of the communication portion where the upstream side and the downstream side of the flow path opening communicate with each other becomes smaller. On the contrary, when the pressure on the upstream side decreases, the wind pressure receiving plate is moved upstream by the reaction force of the balancing spring, and the area of the communication portion increases.

As described above, the shape of the flow path opening is formed so that the air volume is equalized to a predetermined air volume even though the area of the communication portion is changed in response to fluctuations in upstream pressure. In this way, the air volume is adjusted to a predetermined air volume.

(Example) Hereinafter, an example of the constant air volume device according to the present invention will be described in detail with reference to the drawings.

In the figures, particularly in FIG. 1, CAV indicates a constant air volume device, and this constant air volume device CAV includes an outer cylinder 10 for forming an outer shell, and a spaced inside the outer cylinder 10, which is concentric with the outer cylinder 10. A channel opening 2 is provided in the cylinder wall and is provided for communication between the upstream side and the downstream side.
2 and 22 are formed, and the inner cylinder 20
and the flow path openings 22, 22
The valve body 30 also serves as a main member for controlling air volume.

The outer cylinder 10 has a large diameter outer cylinder main body 11.
and duct connecting cylinder parts 14 and 15 connected to both ends of the outer cylinder main body 11 via step walls 12 and 13.
and the duct connecting cylinder part 1
4 and 15, support pieces 31 and 32 for fixing the wind pressure receiving plate guide rod in the valve body portion 30, which will be described later, are fixedly attached.

The inner cylinder 20 is shorter and smaller than the outer cylinder 10 and extends upstream from the one duct connecting cylinder part 15 on the downstream side. It is formed by providing flow path openings 22, 22 which will be described in detail later with reference to FIGS. In addition, 23, 23, 2
Reference numerals 4 and 24 denote shape-retaining bridges that are used to maintain the shape of the channel openings 22 and 22.

Similarly, the valve body portion 30 is a wind pressure receiver that is supported and fixed concentrically with the inner cylinder 20 by the support pieces 31 and 32 for fixing the wind pressure receiver plate guide rod and the support pieces 31 and 32. A wind pressure plate is movably supported by the guide rod 33 through a plate guide rod 33 and a guide rod insertion hole 36 formed in the center, and whose outer peripheral edge is brought into sliding contact with the inner wall surface of the inner cylinder 20. It consists of a receiving plate 34 and a balancing spring 35 disposed on the downstream side of the wind pressure receiving plate 34 and wound around the guide rod 33 between the wind pressure receiving plate 34 and the support piece 32. The rod 33 is provided with a stopper 3 that defines both limits of the movement range of the wind pressure receiving plate 34 to match the flow path openings 22, 22.
7 and 38 are provided.

In addition, the support piece 31 for fixing the wind pressure receiving plate guide rod
may be fixed to the inner cylinder 20 instead of being fixed to the duct connecting cylinder part 14. This makes it easier to get concentric lines.

Finally, the design guidelines for the flow path openings 22, 22 will be explained with reference to FIGS. 2 to 4. First, for convenience of explanation, the flow path openings 22, 22
In Figure 2, which shows how to determine the shape of the opening when there is only one, the horizontal axis
and the vertical axis Y are the horizontal axis along the axial direction of the inner cylinder 20 within the wall surface 21 of the inner cylinder 20, and the vertical axis along the circumferential direction of the inner cylinder 20, respectively, and 22 _O is the horizontal axis X and the vertical axis Y and the curve y obtained by equation [4] below
The flow path opening surrounded by Z is the wind pressure receiving plate 3
This is a communication portion where the upstream side and the downstream side of the channel opening 22 _O communicate with each other on the downstream side of the channel opening 22 O.

Therefore, a calculation formula for determining the shape of the channel opening 22 _O is determined as follows.

() Relationship between air volume and area of communicating part Z Q=c・A・√ ...[1] Q: Air volume (m ³ /s) c: Constant (m ² /√Kg・s) A: Communicating part Z Area (m ² ) Δp: Differential pressure (Kg/m ² ) () Force due to wind pressure applied to the wind pressure receiving plate 34 F=B・ΔP ...[2] F: Force due to wind pressure acting on the wind pressure receiving plate 34 (Kg ) B: Area of wind pressure receiving plate 34 (m ² ) () Reaction force of balance spring 35 Fs=ax+b ...[3] Fs: Reaction force of balance spring 35 (Kg) a: Spring constant (Kg/m ) x: Movement distance of the wind pressure receiving plate 34 (m) b: Initial compressive force of the balancing spring 35 (Kg) Then, during ventilation, the wind pressure and the spring reaction force are balanced. In other words, since F=Fs, [1]
[2] [3] Solving for A from equations yields the following equation.

From the above, A is a function of x, so Q
To keep constant, the area A of the communicating part Z is [4]
All you have to do is create a shape that satisfies the formula.

Next, the curve that determines the area A of the communicating part Z is y
(see Figure 2), the equation of the curve y is y=f
(x), where y is a function of x, and to find y, equation [4] can be differentiated with respect to x. In other words, Thus, a flow path opening forming curve y is obtained.
From this, it is also possible to obtain equation (5') of a curve symmetrical with respect to the X axis. In this way, it is possible to theoretically design the shape of the flow path opening _22O that allows the air volume to be equal to a predetermined air volume even if the upstream pressure fluctuates. In this case, the spring constant of the balancing spring 35 is a.
[5] From formula (5' included), the shape of the flow path opening is: y=k ₁ (x+k ₂ ) ^-3/2 ...[6] Where, x: Axial direction of the inner cylinder Length of the opening y: Length of the opening in the circumferential direction of the inner cylinder k ₁ , k ₂ : Can be expressed as a constant.

By the way, as shown in Fig. 2, when x approaches 0, y becomes a considerably large value, and conversely, in order for y to become 0, x must become ∞, so such flow path openings Since it is technically impossible to form the channel opening 22 _O with the section forming curve y on the cylinder wall 21 of the inner cylinder 20 as it is, when designing the shape of the channel opening, Second
As shown in Figure 3, the areas of the y-curve that asymptotically approach the vertical axis Y and the horizontal axis The areas of the openings are corrected to equal polygonal lines, and the corrected opening forming lines d, e, f, g, h,
For example, by dividing the area of the channel opening 22 _O surrounded by i, j, the vertical axis Y, and the horizontal axis X into two, as shown in FIG. At the same time, the opening forming curves of the respective flow path openings 22, 22 are made symmetrical, and the openings 22, 22 are made symmetrical.
By providing shape-retaining bridges 23, 23, 24, 24 in each of the openings 22, 22, the shape of the flow path openings 22, 22 can be changed to a shape that can be used practically. Design becomes possible.

In addition, in practice, the gap area between the inner cylinder 20 and the wind pressure receiving plate 34 and the value of the constant c in formula [1] vary depending on the shape of the opening, so when manufacturing, the calculated An experimental correction of the aperture is performed.

Furthermore, the number of channel openings is not limited to two as shown in the drawings, but may be three or four. Then, the channel opening is manufactured by punching with a press. Further, in order to change the predetermined air volume, some of the flow path openings are closed off from the outside of the inner cylinder with a closing cover. Further, the cross-sectional shape of the inner cylinder and the shape of the wind pressure receiving plate may be square instead of the circular shape shown in the figure for ease of manufacturing.

(Effects of the invention) As is clear from the above explanation, according to the present invention, no adjustment is required after installation in the duct;
It has become possible to provide a constant air volume device that adjusts the air volume to a predetermined air volume even if the upstream pressure fluctuates.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a vertical cross-sectional side view showing a state in which it is inserted and installed in the middle of an air conditioning duct, and Fig. 2 is a diagram showing a calculated curve for forming an opening for a flow path. FIG. 3 is a diagram showing how to correct the curve for forming the flow path opening, and FIG. 4 is a developed view of the cylindrical wall of the inner cylinder. CAV... Constant air volume device, 10... Outer cylinder, 20...
... Inner cylinder, 21 ... Cylinder wall, 22 ... Channel opening,
30...Valve body part, 33...Wind pressure receiving plate guide rod, 3
4... Wind pressure receiving plate, 35... Balance spring.

Claims (1)

[Claims for Utility Model Registration] An outer cylinder for forming an outer body, disposed in the outer cylinder with a gap between the outer cylinder and the outer cylinder, the downstream end of the gap being closed, and a cylinder. An inner cylinder is formed in the wall with an opening for a flow path for communication between the upstream side and the downstream side, and a wind pressure receiving plate guide rod disposed inside the inner cylinder has an outer peripheral edge formed inside the inner cylinder. In addition to movably supporting the wind pressure receiving plate that slides against the wall surface,
A balancing spring is disposed on the downstream side of the wind pressure receiving plate to stop the wind pressure receiving plate in equilibrium with the wind pressure, and the wind pressure receiving plate is moved in response to the wind pressure on the upstream side, and the flow path opening is moved. The opening forming curve that forms the flow path opening is expressed by the following formula: y=k ₁ (x+k ₂ ) ^{-3/ 2} However, x: Length of the opening in the axial direction of the inner cylinder y: Length of the opening in the circumferential direction of the inner cylinder k ₁ , k ₂ : Characterized by a hyperbola satisfying a constant Constant air volume device.