JP2011204135A - Flow controlling device, liquid discharge device including the flow controlling device, and designing method of the flow controlling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simply-structured flow controlling device capable of easily fixing a flow rate without requiring any special control.SOLUTION: The flow controlling device, which controls a flow rate of a liquid flowing through a flow passage 3 to a set flow rate, includes a Venturi tube 1 arranged in the flow passage 3. The flow passage cross section of a throat part 6 of the Venturi tube 1 is set so that the flow rate is lowered by pressure loss accompanying occurrence of bubbles due to cavitation and substantially fixed to the set flow rate when the flow rate of the liquid passing the Venturi tube 1 exceeds the set flow rate.

Description

  The present invention relates to a flow rate adjusting device, a liquid ejection device provided with the flow rate adjusting device, and a design method of the flow rate adjusting device.

  When water supplied from a water supply source is used, it is often required to adjust the water supply flow rate of the supplied water to the set water supply flow rate. For example, when a constant flow rate of water is intended for the purpose of saving water or the like, it is common to use a method of installing a constant flow valve reported in Patent Document 1 or a method of adjusting by installing a stop cock. .

  However, in the case of the former method, although the required flow rate adjustment function can be sufficiently exhibited, the internal structure is complicated, and it is difficult to secure a built-in space and it is difficult to reduce the cost. In the case of the latter method, especially in an automatic faucet, it is necessary to make adjustments for each faucet terminal.

JP 2005-163823 A

  The present invention has been made in view of the circumstances as described above, and has a simple structure and does not require special adjustment, and can easily achieve a constant flow rate, and a liquid discharge device provided with the flow rate adjustment device An object of the present invention is to provide a method for designing a flow rate adjusting device.

  The present invention is characterized by the following.

  1stly, this invention is a flow volume adjustment apparatus which adjusts the flow volume of the liquid which flows through a flow path to setting flow volume, and is provided with the venturi pipe provided in a flow path. The throat portion of the venturi pipe has a flow path cross-sectional area that satisfies the following formula, and when the liquid passing through the venturi pipe exceeds the set flow rate, the flow rate is suppressed by the pressure loss caused by the generation of bubbles due to cavitation. The flow rate is substantially constant to the set flow rate.

Here, S is the cross-sectional area of the flow path of the throat section, V and P are the flow velocity and pressure at a predetermined position A in the throat section, and V ₁ and P ₁ are the end of the flow path downstream of the venturi pipe, respectively. , The flow velocity and pressure at point B on the streamline at point A, and P ₁ is atmospheric pressure. ρ is the density of the liquid, and Q is the set flow rate.

  Secondly, in the first aspect of the invention, a gas introduction port that opens to the throat portion of the venturi tube is provided.

  Thirdly, in the first or second invention, a plurality of venturi tubes are provided in the flow path direction.

  Fourth, in any one of the first to third inventions, the liquid is tap water.

  Fifthly, in the liquid discharge device of the present invention, the flow rate adjusting device according to any one of the first to fourth aspects of the present invention is provided in the middle of the flow path, and the discharge port is provided at the downstream end of the flow path. .

  Sixth, the present invention is a method for designing a flow rate adjusting device that adjusts the flow rate of the liquid flowing through the flow channel to a set flow rate, and the flow path disconnection of the throat portion of the venturi pipe provided in the flow channel through which the liquid in which the gas is dissolved flows The area is designed to satisfy the following formula.

Here, S is the cross-sectional area of the flow path of the throat section, V and P are the flow velocity and pressure at a predetermined position A in the throat section, and V ₁ and P ₁ are the end of the flow path downstream of the venturi pipe, respectively. , The flow velocity and pressure at point B on the streamline at point A, and P ₁ is atmospheric pressure. ρ is the density of the liquid, and Q is the set flow rate.

  According to the first invention, the structure is simpler than that of a conventional constant flow valve or the like, and a constant flow rate can be easily achieved without requiring any special adjustment.

  According to the second invention, in addition to the bubbles generated by cavitation, the gas is introduced into the throat portion of the venturi tube, so the amount of bubbles in the liquid increases. As a result, the pressure loss increases further, and the flow rate can be made more effective.

  According to the third invention, a plurality of venturi pipes are provided in the direction of the flow path, and the constant flow rate due to the pressure loss due to the generation of bubbles in each of the venturi pipes is performed in stages, so more reliably and A constant flow rate can be achieved more effectively.

  According to the fourth invention, the structure is simple and a constant flow rate of tap water can be easily achieved without requiring special adjustment.

  According to the fifth aspect of the invention, it is possible to discharge a liquid whose flow rate is kept substantially constant regardless of pressure fluctuations in the flow path.

  According to the sixth aspect of the present invention, it is possible to obtain a flow rate adjusting device that has a simple structure as compared with a conventional constant flow rate valve or the like and that can easily achieve a constant flow rate without requiring special adjustment.

It is the schematic explanatory drawing which showed one Embodiment of the liquid discharge apparatus provided with the flow volume adjustment apparatus. It is a graph which shows the relationship between the pressure and flow volume of the fluid in the flow path of the fluid without a bubble mixing, and the fluid with which a bubble was mixed. It is the schematic explanatory drawing which showed another embodiment of the liquid discharge apparatus. It is a saturated vapor pressure diagram of water. It is the schematic explanatory drawing which showed another embodiment of the liquid discharge apparatus.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory view showing an embodiment of a liquid ejection device provided with a flow rate adjusting device.

  Generally, when bubbles are mixed in the fluid flow path, the pressure loss is larger than when bubbles are not mixed. The tendency becomes more prominent as the amount of bubbles increases. FIG. 2 is a graph showing the relationship between the pressure and flow rate of the fluid in the flow path of the fluid in which bubbles are not mixed and the bubbles in fluid. The vertical axis represents pressure, and the horizontal axis represents fluid flow rate. The flow rate of any fluid increases as the pressure in the flow path increases. In the region X surrounded by the dotted line, even when the pressure increases, the flow rate change is smaller than that of the fluid without air bubbles and tends to be a constant flow rate. As described above, this is because the pressure loss increases when bubbles are mixed. The present invention has been made on the basis of the above knowledge. When the flow rate becomes a certain level or more by utilizing the above characteristics, bubbles are generated in the liquid and mixed to achieve a constant flow rate. Yes.

  In the liquid discharge device of FIG. 1, a venturi pipe 1 constituting a flow rate adjusting device is connected in the middle of a water pipe 4 that forms a flow path 3, and a discharge port 2 is provided at the downstream end of the flow path 3. Yes. The upstream end of the flow path 3 is connected to a water supply source such as a water supply, and tap water is supplied to the flow path 3 from the water supply source.

  The venturi tube 1 has a tapered portion 5 in which the flow channel diameter decreases toward the downstream side, a throat portion 6 connected to the tapered portion 5 and having a substantially constant flow channel diameter toward the downstream side, and a flow channel diameter connected to the throat portion 6. It has a tapered divergent portion 7 that gradually expands toward the downstream side. The tap water flowing from the water supply source to the tap pipe 4 has a flow velocity that increases in the tapered portion 5 of the venturi 1, the flow velocity is maximized in the throat portion 6 having the smallest channel diameter, and the static pressure is minimized. And in the divergent part 7, the flow velocity of tap water decreases and the static pressure recovers.

Here, an arbitrary position of the throat portion 6 of the venturi pipe 1 is designated as point A, and the tap water outlet portion (discharge port 2) of the water pipe 4 at the end of the flow path 3 downstream from the divergent portion 7 of the venturi pipe 1 is shown. A position on the same streamline as point A is B point. If the pressure and flow velocity at point A are P and V, the pressure and flow velocity at point B are P ₁ and V _1, and the density of tap water is ρ, the fluid is not viscous and is a steady flow and is incompressible. For example, the relationship is as shown in the following equation (Bernoulli's theorem). Since point B is a portion which is opened to the atmosphere, P ₁ is atmospheric pressure.

  In the flow rate adjusting device according to the present embodiment, when tap water exceeding the set flow rate passes through the venturi 1, the pressure loss is increased, thereby suppressing the flow rate and making the set flow rate substantially constant. In order to increase the pressure loss, it is necessary to use tap water mixed with bubbles as described above. Therefore, in the present embodiment, in the throat portion where the static pressure is the lowest, the static pressure is made equal to or lower than the saturated vapor pressure of the tap water temperature, the tap water is boiled (cavitation), and bubbles are generated in the tap water. . The set flow rate is

Therefore, the above formulas (1) and (2) and the following formulas (3) and (4)

If the channel cross-sectional area S of the throat portion of the venturi pipe that satisfies the above is set, when the tap water passing through the venturi pipe 1 exceeds the set flow rate, the tap water is boiled to generate bubbles in the tap water. it can. Since tap water is generally dissolved in a saturated state, bubbles can be easily deposited in tap water by boiling the tap water. Therefore, the venturi tube according to this embodiment is set so that the flow passage cross-sectional area S of the throat portion satisfies the above formula.

  As described above, the liquid ejection apparatus according to the present embodiment includes a flow rate adjustment device that has a simple structure, does not require special adjustment, and can easily achieve a constant flow rate, and has an excellent flow rate adjustment function. It should be noted that the flow rate adjusting device is not limited to the flow path cross-sectional area S obtained by the above formula, but has a flow rate adjusting function in the same manner even if it is slightly different. Become.

  FIG. 3 is a schematic explanatory view showing another embodiment of the liquid ejection apparatus. The same parts as those of the liquid ejection apparatus shown in FIG.

  3 has a gas introduction port 8 that opens to the throat portion 6 of the venturi pipe 1 constituting the flow rate adjusting device, and a pipe 9 is connected to the opening, and the throat and the external space are connected through the pipe 9. The part 6 is in communication. Since the static pressure of the throat portion 6 is set to be equal to or lower than the saturated vapor pressure as described above, the static pressure is the atmospheric pressure as apparent from the saturated vapor pressure diagram of water shown in FIG. It is lower. When the static pressure of the throat portion 6 is lower than atmospheric pressure, external air is naturally sucked from the gas inlet 8 through the pipe 9.

  Therefore, in this embodiment, in addition to bubbles generated by cavitation, bubbles taken from external air are mixed in the tap water, so the amount of bubbles in the tap water increases. Thereby, pressure loss increases more and it can aim at the constant flow volume of tap water more effectively. In this embodiment, it is not necessary to forcibly send external air into the flow path using power such as an air pump, and the flow of tap water is used, so that the cost is low. The structure is simple.

FIG. 5 is a schematic explanatory view showing still another embodiment of the liquid ejection apparatus. The same parts as those of the liquid ejection device shown in FIGS. 1 and 3 are denoted by the same reference numerals and description thereof is omitted. In the liquid ejection device of FIG. 5, the venturi 1 constituting the flow rate adjusting device in the liquid ejection device of FIG. , 1 'are provided in the flow path direction. Specifically, two venturi pipes 1 and 1 ′ are connected to the upstream side and the downstream side of the water pipe 4. The downstream venturi tube 1 ′ has a tapered portion 5 ′ throat portion 6 ′ and a divergent portion 7 ′, similar to the upstream venturi tube 1. In this embodiment, cavitation is generated in each of the venturi tubes 1 and 1 ′ to generate bubbles. Since the flow rate is suppressed by pressure loss in the upstream venturi 1 and the downstream venturi 1 'in stages, the constant flow rate of tap water can be achieved more reliably and more effectively. In addition, the flow path cross-sectional areas S and S ′ of the throat portions 6 and 6 ′ of the respective venturi pipes 1 and 1 ′ are set so as to satisfy the following expression, similarly to the flow rate adjusting device of FIG.

  Here, V ′ and P ′ are the flow velocity and pressure at point C in the throat portion 6 ′ of the venturi tube 1 ′, and points A, B, and C are all located on the same streamline.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, when a plurality of flow rate adjusting devices are provided as shown in FIG. 5, a gas introduction port that opens to at least one venturi throat portion may be provided. In addition, the flow rate adjusting device and the liquid discharge device are widely used in fields that require flow rate adjustment, and can be applied to, for example, water purifiers, water heaters, toilet system related devices, and the like.

1, 1 'Venturi tube 2 Discharge port 3 Flow path 6, 6' Throat section 8 Gas inlet

Claims (6)

A flow rate adjusting device for adjusting a flow rate of a liquid flowing in a flow path to a set flow rate, comprising a venturi pipe provided in the flow path, wherein the throat portion of the venturi pipe has a flow passage cross-sectional area of the throat portion as S, and the throat portion Let V and P be the flow velocity and pressure at a predetermined position A in V, respectively, and let V ₁ and P ₁ (= the flow velocity and pressure at point B on the streamline of point A at the end of the flow path downstream from the venturi pipe respectively. Atmospheric pressure), the liquid density is ρ, and the set flow rate is Q.

If the liquid passing through the venturi tube exceeds the set flow rate, the flow rate is suppressed by the pressure loss associated with the generation of bubbles due to cavitation, and the set flow rate is made almost constant. A flow rate adjusting device characterized in that:   The flow rate adjusting device according to claim 1, further comprising a gas introduction port that opens to a throat portion of the venturi pipe.   The flow rate adjusting device according to claim 1 or 2, wherein a plurality of venturi pipes are provided in the direction of the flow path.   The flow rate adjusting device according to any one of claims 1 to 3, wherein the liquid flowing in the flow path is tap water.   5. A liquid ejecting apparatus according to claim 1, wherein the flow rate adjusting device according to claim 1 is provided in the middle of the flow path, and a discharge port is provided at a downstream end of the flow path. A design method of a flow rate adjusting device for adjusting a flow rate of a liquid flowing in a flow channel to a set flow rate, wherein S is a flow channel cross-sectional area of a throat portion of a venturi tube provided in a flow channel in which a liquid in which a gas is dissolved flows. Let V and P be the flow velocity and pressure at a predetermined position A in V, respectively, and let V ₁ and P ₁ (= the flow velocity and pressure at point B on the streamline of point A at the end of the flow path downstream from the venturi pipe respectively. Atmospheric pressure), the liquid density is ρ, and the set flow rate is Q.

A flow rate adjusting device designing method, wherein the flow passage cross-sectional area S of the throat portion of the venturi pipe is designed so as to satisfy the above.

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