JPS6146675B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a method for pumps whose motors are overloaded when the flow rate is small, such as Wesco pumps, by providing a return flow path to absorb a portion of the total pump discharge flow. The pump can be operated continuously even if the faucet flow rate is small by returning the flow to the spout, and the pressure tank is downsized or completely eliminated by sensing the flow rate of the pump device (hereinafter referred to as tankless pump device). This invention relates to an automatic pump device that performs automatic control.

[Prior art]

FIG. 1 is a system diagram showing an example of a conventional automatic tankless pump device. In this diagram, 1 is a pump whose required power increases as the head increases, such as a Wesco pump. 2 is a suction pipe, which is connected to a water source via a check valve 3. 4 is a small pressure tank, and 5 is a pressure switch, both of which are connected to the pump discharge channel 6. Reference numeral 7 denotes a relief valve that closes below a certain predetermined pressure, and is connected to the reflux flow path 8 . Reference numeral 9 denotes a resistance valve connected within the faucet flow path 10 for detecting the flow rate flowing out from the faucet 11 in the form of pressure. A differential pressure valve 12 connected to the reflux path 8 senses the flow rate converted into a pressure difference through a front pressure measurement hole 13 and a back pressure measurement hole 14 for detecting the front pressure and back pressure of the resistance valve 9. However, when this differential pressure falls below a certain value, the valve is closed and the reflux is stopped. An example of this differential pressure valve 12 is shown in FIG.

In FIG. 2, the main body 15 has a packing 17 attached to the edge of the hole 16, and a pressure chamber case 18.
A diaphragm 19 is held between the diaphragm 19 and an operating shaft 20 is held in the center of the diaphragm 19. Reference numeral 21 denotes a pressure spring, and the load is adjusted to an appropriate value by an adjustment screw 22. 23 and 24 are differential pressure valve pressure chambers, respectively, in which the pressure from the front pressure measurement hole 13 is guided to the differential pressure valve pressure chamber 23, and the pressure from the rear pressure measurement hole 14 is introduced to the differential pressure valve pressure chamber 24. 2
5 is an O-ring for isolating the differential pressure valve pressure chamber 23 from the reflux flow path 8.

The conventional automatic tankless pump device is configured as described above. For example, when water is started from the faucet 11 while the pump 1 is stopped, the pressure in the pump discharge passage 6 decreases, and the on-pressure of the pressure switch 5 decreases. It reaches Pon and pump 1 starts. When the faucet is fully open and the faucet flow rate Q ₁ is large, the discharge pressure P ₀ of the pump 1 is low and lower than the pressure P ₁ at which the relief valve 7 opens, so there is no flow back to the suction port. However, the differential pressure valve 12 is in an open state because the differential pressure ΔP before and after the resistance valve 9 is large. Next, as the faucet 11 is turned down, the discharge pressure of the pump 1 increases, and the pressure at which the relief valve 7 begins to open
When the pressure becomes higher than P ₁ , the relief valve 7 begins to open, and since the differential pressure valve 12 is still open, part of the discharge flow rate Q ₀ of the pump 1 begins to flow back to the suction port, so even if the faucet 11 is closed, the flow continues. The flow rate Q ₀ does not decrease so much, and the discharge pressure also does not increase so much. However, as the faucet 11 is further tightened, the faucet flow rate increases.
When Q ₁ becomes very small, the differential pressure ΔP across the resistance valve 9 becomes very small, so the differential pressure valve 12 is closed, and the reflux flow rate Q ₂ decreases, so the discharge pressure of the pump 1 also increases. The pump 1 stops when the off-pressure _P0FF of the pressure switch 5 is reached.

[Problem that the invention seeks to solve]

As mentioned above, in the conventional automatic tankless pump device, in order to sense the faucet flow rate Q ₁ , a resistance valve 9 is purposely provided to cause a loss, so the pump device when the faucet flow rate Q ₁ is larger than a certain level. This will cause the actual head to decrease. Further, the pressure difference ΔP before and after the resistance valve 9 is the flow rate of the fluid passing through the resistance valve 9, that is, the faucet flow rate Q ₁
Since it is proportional to the square of , there was a problem that the sensitivity was poor at the critical minute flow rate.

This invention eliminates the resistance valve 9 that causes unnecessary loss.
It is an object of the present invention to provide an automatic tankless pump device which has a high sensitivity and ability to detect a faucet flow rate when the faucet flow rate _Q1 is a minute flow rate.

[Means for solving problems]

The automatic pump device according to the present invention branches a pump discharge flow path having a pressure switch that starts and stops the pump with a predetermined pressure width into a faucet flow path and a return flow path, and controls the flow rate of both flow paths. A differential pressure valve that senses pressure in the form of pressure and closes the valve when the difference between both flow rates falls below a predetermined value, and a relief valve that closes the valve when the pump discharge pressure is below a predetermined pump discharge pressure are interposed in the above-mentioned reflux flow path. It is.

[Effect]

In this invention, when the faucet flow rate becomes very small, the return flow path is closed by the differential pressure valve and the pressure rises rapidly, which causes the pressure switch to operate and stop the pump.

〔Example〕

FIG. 3 is a system diagram of an automatic tankless pump device showing an embodiment of the present invention. In this figure, numerals 1 to 8 and 10 to 12 are the same parts as in the conventional device shown in FIG. 1 above. There is no resistance valve 9, front pressure measurement hole 13, and back pressure measurement hole 14 of the resistance valve, and instead they are placed as close as possible to the pump discharge flow path 6 and reflux flow path 8 to the extent that there is almost no influence from branching, and the wall surface static. A pressure hole 26 and a wall static pressure hole 27 are provided, and the wall static pressure hole 26 is connected to the differential pressure valve 12 shown in FIG.
The differential pressure valve pressure chamber 24 and the wall static pressure hole 27 are connected to the differential pressure valve pressure chamber 23, respectively. In addition, the piping structure of the part where the pump discharge flow path 6 branches into the reflux flow path 8 and the faucet flow path 10 is such that the pump discharge flow path 6 and the reflux flow path 8 are connected linearly with the same cross-sectional area in principle. It is better to have

Next, the operation will be explained. The total pressures at the cross section A of the pump discharge passage 6 at the position where the wall static pressure hole 26 is provided and the cross section B of the return flow passage 8 at the position where the wall static pressure hole 27 is provided are expressed as P _tA and P _tB , respectively. Then, since there is not much distance between the two cross sections and they are connected linearly, it becomes approximately P _tA =P _tB . In addition, the dynamic pressure at cross section A and cross section B is P _D
Assuming that _A , P _DB and the static pressure are P _SA and P _SB , the cross-sectional area of the two channels is equal, so the difference (Q ² ₀ - Q ² ₂ ) in the square of the flow rate of the two channels is (P _DA - P _DB ).
From the above two facts, (Q ² ₀ −Q ² ₂ ) is almost (P _SB −
It can be seen that it is proportional to P _SA ). . The relationship between the magnitude of the differential pressure ΔP between the differential pressure valve pressure chamber 23 and the differential pressure valve pressure chamber 24 of the differential pressure valve ₁₂ with respect to the faucet flow rate Q ₁ is as described above in the case of pumping using the conventional resistance valve 9.
In the case of the present invention, it is _a function of the difference between the square of the pump discharge flow rate _{Q 0} ^and the square of the reflux flow rate Q ₂ , that is, ΔP = b (Q ² ₀ - Q ² ₂ )
Therefore, the curves shown in FIG. 4 are obtained (a and b are constants). As can be seen from this figure, the faucet flow rate sensing device according to the present invention has a higher faucet flow rate Q ₁ than the conventional resistance valve 9.
It has good sensitivity when the pressure is small, and the differential pressure valve 12
The displacement of the operating shaft 20 also occurs more rapidly when the faucet flow rate Q ₁ is small, so the pressure increase due to the closure of the return flow path 8 also occurs more rapidly, and the displacement of the actuating shaft 20 occurs more rapidly when the faucet flow rate Q ₁ is detected with better accuracy. This makes it possible to stop the pump. The characteristics of the pump device according to the present invention are shown in FIG. 5 in comparison with the conventional pump device.

In Fig. 5, the horizontal axis represents the pump discharge flow rate Q ₀ and the faucet flow rate Q ₁ , and the vertical axis represents the total head H ₀ and the actual head H. The curve is the conventional H-Q ₁ characteristic, and the curve is the curve of the invention. shows the H-Q ₁ characteristics of The straight line is the H ₀ −Q ₀ characteristic of the pump alone. _H1 is the lift at which the pressure switch 5 is turned on, _H2 is the lift at which the pressure switch 5 is turned off, and _H3 is the lift at which the motor is overloaded.

Note that the above-mentioned embodiments have been explained only when the pump discharge passage 6 and the reflux passage 8 are linearly connected with the same cross-sectional area, but when the cross-sectional areas are different or the reflux passage is connected in a straight line, Even if the differential pressure valve 12 and the pressure spring 2 of the differential pressure valve 12 are not connected,
The above operation can be performed by calibrating with the adjustment screw 1 and the adjustment screw 22.

〔Effect of the invention〕

As explained above, this invention senses two flow rates in the form of pressure, the pump discharge total flow rate and the reflux flow rate, and uses a differential pressure valve that operates when the difference between these two flow rates becomes less than a predetermined value to recirculate the flow. Since the pressure switch is activated and the pump is controlled by closing the flow path and increasing the pressure, there is no need for a resistance valve in the faucet flow path as in conventional systems, and there is no unnecessary loss due to the resistance valve. There are effects such as good sensitivity when the faucet flow path is minute and improved control accuracy of the pump.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an example of a conventional automatic tankless pump device, Fig. 2 is a partial cross-sectional view showing an example of the structure of a differential pressure valve used in the device of Fig. 1, and Fig. 3 is a system diagram of an example of a conventional automatic tankless pump device. The figure is a system diagram showing one embodiment of the present invention, and Figures 4 and 5 compare the faucet flow rate sensing characteristics and H-Q ₁ characteristics of the embodiment of Figure 3 with those of a conventional device. FIG. In the figure, 1 is a pump, 4 is a small pressure tank, 5 is a pressure switch, 6 is a pump discharge channel, 7 is a relief valve, 8 is a reflux channel, 10 is a faucet channel, 12 is a differential pressure valve, 26, 27 is a wall static pressure hole. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A pump discharge flow path connected to the discharge side of the pump, a faucet flow path formed by branching this pump discharge flow path and allowing the pump discharge water to flow out to a faucet, and one part of the pump discharge water. a reflux passage for refluxing the part to the pump suction side; a relief valve interposed in the reflux passage for closing the reflux passage and preventing reflux when the pump discharge pressure is below a predetermined pump discharge pressure; 2 of the total pump discharge flow rate and the above recirculation flow rate
A differential pressure valve that senses two flow rates in the form of pressure and closes the reflux flow path to prevent reflux when the difference between the two flow rates becomes less than a predetermined value; and a pressure switch for starting and stopping the pump. 2 The pump discharge flow path and the reflux flow path have the same cross-sectional area,
The automatic pump device according to claim 1, wherein the pump device is connected in a straight line.