JPH0129998B2 - - 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 passage 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 flow path 8 converts the flow rate 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. The valve is sensed and adjusted to close the valve and stop reflux when this differential pressure falls below a certain value. An example of this differential pressure valve 12 is
As shown in the figure.

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. Pump 1 is started. 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 remains open because the differential pressure ΔP across the resistance valve 9 is large. Next, as the faucet 11 is turned down, the discharge pressure of the pump 1 increases, and when it becomes higher than the pressure P1 at which the relief valve ₇ begins to open, the relief valve 7 begins to open.
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.
Furthermore, even if the faucet 11 is closed, the recirculation flow rate Q ₀ does not decrease much and the discharge pressure does not increase 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. When the off pressure of the pressure switch 5 reaches _P0FF , the pump 1 stops.

[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. Moreover, the pressure difference ΔP between the front and rear sides generated by the resistance valve 9 is the flow velocity 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.
The object of the present invention is to obtain an automatic tankless pump device that has a faucet flow rate sensing ability with high sensitivity when the faucet flow rate _Q1 is a minute flow rate.

[Means for solving the problem] The automatic pump device according to the present invention branches the pump discharge flow path into a faucet flow path and a reflux flow path, and senses the flow rate of both flow paths in the form of pressure. A differential pressure valve that opens when the difference in flow rate is below a predetermined value, a relief valve that is interposed in the reflux flow path and closes the valve when the pump discharge pressure is below a predetermined pressure, and a relief valve that starts the pump with a predetermined pressure range. The pressure switch is connected to the pump discharge flow path via the differential pressure valve.

[Effect]

In this invention, when the faucet flow rate becomes very small, the differential pressure valve opens, and the pressure switch is thereby connected to the pump discharge passage, detects an increase in the pump discharge pressure, and stops 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 and 11 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 a differential pressure valve 29 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.

The main body 30 has a hole 32 in which a packing 31 is attached, and an operating shaft 34 with an integrated valve body 33 is inserted into the hole 32.
passes through the center of Other symbols 21 to 25 are the same as those shown in FIG. The function of this pressure switch differential pressure valve 29 is exactly opposite to that of the conventional differential pressure valve 12, and the valve is opened when the difference ΔP between the two pressure chambers is small and closed when it is large. Moreover, the small pressure tank 4 needs to be connected to the faucet flow path 10 instead of the pump discharge flow path 6 in this case. Furthermore, 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 as follows.
In principle, it is preferable that the pump discharge channel 6 and the reflux channel 8 have the same cross-sectional area and are connected linearly.

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 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 pressures at cross section A and cross section B are respectively P _DA ,
If 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 in the square of the flow rate of the two channels (Q ² ₀ − Q ² ₂ ) is (P _DA − P _DB ) is proportional to From the above two facts, it can be seen that (Q ² ₀ −Q ² ₂ ) is approximately proportional to (P _SB −P _SA ). In the case of the conventional resistance valve ₉ , 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 the square of the faucet flow rate Q ₁ as described above. In the case of this 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 ). Because there is
The curves shown in FIG. 5 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 better sensitivity when the faucet flow rate Q ₁ is minute than that using the conventional resistance valve 9. The operation of this embodiment is such that, for example, when the faucet 11 is opened with the pump 1 stopped, the water stored in the small pressure tank 4 flows out and the pressure in the flow path decreases. At this time, since water is not flowing through the two wall static pressure holes 26 and 28 for sensing the faucet flow rate, the pressure switch differential pressure valve 29 is open. When the pressure reaches the pressure P _po of the pressure switch, pump 1 starts,
As water flows out of the pump discharge channel 6, the differential pressure ΔP between the two wall static pressure holes 26 and 27 increases, so the differential pressure valve 29 for the pressure switch is closed and the pressure at the pressure switch 5 is the same as the pressure at the time when the pressure switch 5 is closed. sealed. Next, when the faucet 11 is turned down, the relief valve 7 begins to open at a certain pressure P ₁ and recirculation begins, so even if the faucet 11 is further turned down, the discharge pressure of the pump 1 does not increase as much. At this point, the discharge pressure of the pump 1 has already reached the pressure _P0FF at which the pressure switch 5 is turned off, but the pressure switch 5 remains sealed, so the pump 1 continues to operate. Further, by tightening the faucet 11, the faucet flow rate _Q1 becomes very small, and when it reaches a certain predetermined flow rate, the pressure switch differential pressure valve 29 is suddenly opened and the pressure switch 5 is activated, and the pump 1 is stopped. This characteristic is shown in FIG.

In Fig. 6, the horizontal axis shows the pump discharge flow rate Q ₀ and the faucet flow rate Q ₁ , the vertical axis shows the total head H ₀ and the actual head H, and the curve shows the conventional H-Q ₁ characteristic.
The curve shows the HQ ₁ characteristics of this invention. 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.

In addition, each of the above-mentioned embodiments has been explained only in the case where the pump discharge flow path 6 and the reflux flow path 8 are linearly connected with the same cross-sectional area, but when the cross-sectional area is different or Even if they are not connected linearly, the above operation can be performed by calibrating the pressure spring 21 and adjustment screw 22 of the pressure switch differential pressure valve 29.

〔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 increase the pressure. By connecting the switch to the pump discharge flow path, the pressure switch is operated and the pump is controlled, so there is no need for a resistance valve in the faucet flow path unlike in the past, and there is no wasteful loss caused by the resistance valve. There are effects such as good sensitivity when the flow path is minute and improved control accuracy of the pump.

[Brief explanation of drawings]

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. Figure 4 is a system diagram showing one embodiment of the present invention, Figure 4 is a partial cross-sectional view showing an example of the structure of the differential pressure valve used in the device shown in Figure 3, and Figure 5
The figure shows the sensing characteristics of the faucet flow rate of the embodiment shown in Fig. 3 in comparison with that of the conventional device.
FIG. 3 is a diagram showing the H-Q ₁ characteristics of the illustrated embodiment in comparison with that of a conventional device. 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 29 is a wall static pressure hole, and 29 is a differential pressure valve for a pressure switch. 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 blocking the reflux passage and preventing reflux when the pump discharge pressure is below a predetermined pump discharge pressure; There is a differential pressure valve that senses the two flow rates of the pump discharge total flow rate and the above-mentioned reflux flow rate in the form of pressure and opens the valve when the difference between these two flow rates becomes less than a predetermined value, and a differential pressure valve that operates with a predetermined pressure width. An automatic pump device comprising: a pressure switch for starting and stopping the pump, the pressure switch being connected to the pump discharge flow path via the differential pressure valve. 2. The automatic pump device according to claim 1, wherein the pump discharge flow path and the reflux flow path have the same cross-sectional area and are connected linearly.