JPS6329892Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention is a pump abnormal operation prevention device that cuts off the power to the pump motor when the pump impeller locks or the pump runs dry. Regarding.

(B) Prior Art The most common electric circuit for a pump connects a pressure switch in series with the pump motor, which closes the contacts when the water pressure in the discharge pipe drops below a certain value. However, with this circuit, chattering is likely to occur when the faucet is turned off.

In order to eliminate such drawbacks, as shown in Fig. 1, a pressure switch 1 that closes the contact when the water pressure in the discharge pipe becomes below a certain value, and a pressure switch 1 that closes the contact when the water pressure in the discharge pipe becomes lower than a certain value, and A circuit has also been considered in which the flow rate switch 2 that closes the contact is connected in parallel, and this parallel circuit is connected in series with the pump motor 3. However, even with this circuit, it is not possible to prevent excessive current when the pump impeller locks or overheating during idle operation.To prevent these abnormal conditions, overcurrent prevention relay 4 and overheat prevention relay 5 are was connected.

However, in order for these safety devices to operate reliably, the setting current of the overcurrent prevention relay 4 must be accurate, and the overheat prevention relay 5 must have a structure that is not affected by the ambient temperature. As a practical matter, it was difficult to ensure reliable operation.

(c) Purpose This proposal aims to provide a device for preventing abnormal operation of pumps that does not require a very high degree of setting accuracy and is not affected by ambient temperature.

(d) Configuration To achieve this objective, the present invention connects the common contact of the flow rate switch connected in parallel with the pressure switch to the pump motor side, and also provides a normally closed contact on the flow rate switch, and A delay timer is connected, and a contact that opens when a certain period of time has elapsed after energization of the timer is connected in series with the pump motor.

(E) Effect When the water faucet is opened in this configuration, the pressure switch closes and the pump motor rotates, and then the flow rate switch also closes to the normally open contact side and the pump motor continues to rotate, but the pump locks. Since water does not flow into the discharge pipe during idle operation or idle operation, the flow rate switch remains closed to the normally closed contact side, energizes the delay timer, and opens the contact in series with the pump motor when a certain period of time has elapsed. , stop this pump motor. Also, when the faucet is closed, the flow disappears and the flow rate switch switches to the normally closed contact on the delay timer side, but in this switching state, the pressure switch has already been opened, and this pressure switch switches to the normally closed contact on the delay timer side. Since the power is cut off and the normally closed contact of the flow switch is not energized, the delay timer is not energized and the timer contact remains closed, so that the next time the faucet is opened. In this case, the pump motor can be energized and driven without any problem through the closed timer contact.

(F) Example The following example will be explained based on Fig. 2. 1 is a pressure switch that closes the contact when the pressure inside the discharge pipe of the pump falls below a certain value, and 2 is a pressure switch that closes the contact when a certain amount of water flows inside the discharge pipe. Both switches are connected in parallel to each other, and the pump motor 3 is connected in series to this parallel circuit 6. The pressure switch 1 is configured to open the pressure switch contact prior to the opening operation of the flow rate switch 2 during a pressure increase process such as when closing a water faucet. During the opening operation, the contact is bypassed by the conductive path of the flow rate switch 2 to avoid energization of the pressure switch contact, thereby preventing the occurrence of chattering as in the prior art shown in FIG.

The flow rate switch 2 has its common contact 2.
C is connected to the pump motor 3 side, and has a normally closed contact B. A delay timer 7 is connected to the normally closed contact, and the contact 8, which opens when a certain period of time has elapsed after the timer is energized, is connected to the pump motor 3 side. 3 is connected in series.

The operation of the above configuration will be explained below. When the faucet is opened, the pressure in the pump discharge pipe decreases, so the pressure switch 1 closes the contacts and energizes the pump motor 3, starting the pump. Operation of the pump causes a flow of water in the discharge pipe, which causes the flow rate switch 2 to close the normally open contact A and continue to energize the pump motor 3. As the faucet is turned down, the pressure in the discharge pipe increases and pressure switch 1 is opened before flow switch 2, but as long as a certain amount of water is flowing, flow switch 2 closes normally open contact A. Therefore, current continues to flow to the pump motor 3. When the faucet is almost completely closed, the flow of water in the discharge pipe is almost eliminated, so the flow rate switch 2 opens the normally open contact I to cut off the power to the pump motor 3 and stop the operation. Furthermore, when the faucet is closed, the flow disappears and the flow rate switch 2 switches to the normally closed contact B on the delay timer 7 side, but in this switching state, the pressure switch 1 has already been opened and this The pressure switch 1 shuts off the power, and the common contact 2C and the normally closed contact RO of the flow rate switch 2 are not energized, so the delay timer 7 is not energized, so the timer contact 8 remains closed. Therefore, when the faucet is opened next time, the pump motor 3 will be energized and driven without any trouble through the timer contact 8 in the closed state.

However, if the pump becomes locked due to a foreign object caught in it, or if the water source runs out and runs dry, the contact of pressure switch 1 closes due to the drop in water pressure in the discharge pipe, and the flow rate decreases due to the loss of water flow. The switch 2 closes to the normally closed contact (B) side, and current flows through both contacts in series to energize the delay timer 7. When a certain period of time elapses after the timer is energized, the contact 8 is opened, so that the timer motor 3 is de-energized and the operation is stopped. If the timer contact 8 is provided with a normally open contact and an alarm device is connected to the normally open contact, an alarm can be issued when the contact 8 is activated by the delay timer.

(g) Effects Since the present invention is configured as described above, there is no need to use overcurrent prevention relays that require precision or overheat prevention relays that are affected by ambient temperature.
It is possible to provide an abnormal operation prevention device that operates reliably. Furthermore, since the delay timer used in the present invention does not require much precision, it can be manufactured easily and at low cost.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 show the conventional and proposed pump abnormal operation prevention devices, respectively. 1...Pressure switch, 2...Flow rate switch, 2
C... Common contact, A... Normally open contact, B... Normally closed contact, 3... Pump motor, 6... Parallel circuit, 7...
...Delay timer, 8...Delay timer contact.

Claims (1)

[Claims for Utility Model Registration] A flow rate switch that closes a contact when there is a constant flow rate in the discharge pipe of a pump, a contact that closes when the pressure in the discharge pipe decreases, and an opening operation of the flow rate switch in the process of increasing pressure. A pressure switch that opens a contact in advance, and a pump motor that connects the pressure switch and the flow rate switch in parallel with each other and connects in series to this parallel circuit, the common contact of the flow rate switch being connected to the pump motor in series. is connected to the pump motor side, a normally closed contact is provided on the flow rate switch, a delay timer is connected to the contact, and the contact opens when a certain period of time has elapsed after energization of the delay timer.
A pump abnormal operation prevention device connected in series with the pump motor.