JPS6118037B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combination pump of a jet pump and an electric pump.

This type of combination pump is used for pumping hot liquids. In other words, high-temperature liquid re-evaporates when it is brought to a low-temperature region, so it cannot be pumped by an electric pump alone.In order to increase the pressure on the suction side of the electric pump and prevent re-evaporation within the electric pump, a jet pump is used in combination. It is used. However, with conventional combination pumps, when the high-temperature liquid from the inflow passage decreases or the jet flow from the jet pump nozzle becomes weak, the pressure on the suction side of the electric pump becomes insufficient and cavitation occurs. There was a problem that the pumping capacity decreased or disappeared.

It is an object of the present invention to provide a combination pump that can maintain normal pumping action regardless of fluctuations in the amount of inflowing liquid. The structure of the present invention designed to achieve the above object is to guide the liquid discharged from the discharge port of the electric pump to the nozzle of the jet pump through the circulation passage, and to guide the liquid discharged from the diffuser of the jet pump to the suction port of the electric pump. A valve that is opened and closed by a drive means is arranged in a pressure feeding passage branched from the circulation passage, which leads the pressurized high temperature liquid to the suction chamber of the jet pump through the inlet passage, and guides the pressurized liquid in the circulation passage on the discharge port side to the destination. , the flow rate in the inlet passage or the suction port side of the electric pump is detected by the flow rate detection means, and a memory element is stored that stores a characteristic curve showing the relationship between the head and the amount of liquid pumped so that the electric pump can achieve maximum efficiency without causing cavitation. When the detected flow rate decreases/increases, a control signal is sent to the drive means to open/close the valve so that the opening degree of the valve disposed in the pressure-feeding passage becomes smaller/larger, and the valve is opened/closed on the discharge port side according to the detected flow rate. The pressure in the circulation passage is changed in accordance with the characteristic curve of the head of the electric pump versus the amount of liquid pumped, so that the liquid flows through the pressure-feeding passage.

The operation of the above configuration is as follows.

When the amount of liquid to be pressurized that flows into the suction chamber of the jet pump through the inflow passage decreases, the amount of liquid supplied to the electric pump decreases, and the force of the jet stream from the nozzle of the jet pump also weakens. The pressure on the suction port side decreases. Therefore, the signal from the flow rate detection means that detects a decrease in the flow rate in the inflow passage or the suction port side of the electric pump is processed by the control means, and a control signal is sent to the drive means to control the opening of the valve disposed in the pressure feeding passage. Drive in the direction of becoming smaller.
Then, the pressure in the circulation passage on the discharge port side increases because the amount of liquid flowing out from the pressure passage decreases, and the force of the jet stream from the nozzle increases, so the pressure on the suction port side of the electric pump increases. On the other hand, when the amount of pressurized liquid increases, the control means processes the signal from the flow rate detection means that detects this and sends a control signal to the drive means to drive the valve in a direction that increases the opening degree. do. The opening degree of the valve, which is controlled according to the amount of liquid to be pressurized, is controlled so that the pressure in the circulation passage on the discharge port side follows the characteristic curve of the electric pump, so cavitation does not occur and the electric pump pressurizes the liquid. It is possible to prevent the decrease or disappearance of abilities.

Next, a more detailed explanation will be given based on the embodiment shown in FIG.

1 indicates an electric pump. As the electric pump 1, a centrifugal pump driven by an electric motor is often used, and the type of pump is selected in consideration of the required head, amount of pumped liquid, etc. The discharge port 2 and suction port 3 of the electric pump 1 are connected in a loop through circulation passages 4 and 5. A jet pump 6 having an ejector structure is disposed in the circulation passages 4 and 5. The discharge port side circulation passage 4 connects the discharge port 2 of the electric pump 1 and the jet pump 6.
The diffuser of the jet pump 6 and the suction port 3 of the electric pump 1 are connected by a circulation passage 5 on the suction port side. Suction port side circulation passage 5
A flow rate detection means 7 for detecting the amount of liquid sucked into the electric pump 1 is arranged. This detection means is an electric one that sends a signal depending on the flow rate of the outflow. An inflow passage 8 is provided in communication with a suction chamber formed between the nozzle and the nozzle of the jet pump 6, and a pressure feeding passage 9 is provided branching off from the circulation passage 4 on the discharge port side. These passages 4, 5,
8 and 9 can be made of tubular material. A valve 10 is arranged in the pressure feeding passage 9 to change the opening degree. valve 10
A drive means 11 is attached to the drive means 11, and the opening degree of the valve 10, that is, the opening degree of the pressure feeding passage 9 is changed by the action of the drive means 11. Depending on the opening degree of the valve 10,
The amount of liquid that passes through the valve 10 and is sent from the pressure feed passage 9 to the pressurized system changes, and accordingly, the electric pump 1
The pressure in the circulation passage 4 on the discharge port side changes. For example, if the opening degree of the valve 10 becomes smaller, the amount of liquid sent out from the pressure passage 9 decreases, the amount of liquid flowing through the circulation passage 4 increases, and the pressure within this passage 4 increases. Furthermore, as the opening degree of the valve 10 increases, the amount of liquid sent out from the pressure feeding passage 9 increases, the amount of liquid flowing through the circulation passage 4 decreases, and the pressure within this passage 4 decreases. In this embodiment, the driving means 11 is an electric motor, such as a stepping motor or a pulse motor. A pressure detection means 12 is attached to the circulation passage 4 . This pressure detection means 12 is an electric type that sends a signal according to the detected pressure. Reference numeral 13 indicates a control means that receives a signal from the flow rate detection means 7 and sends a control signal to the drive means 11. In the case of this embodiment, the control means 13
is a microcomputer consisting of an LSI, and has a memory element that stores a characteristic curve showing the relationship between the head and the amount of liquid pumped so that the electric pump 1 can achieve maximum efficiency without causing cavitation, and the By processing the received signal, the opening degree of the valve 10 is changed according to the change in the detected flow rate, and the pressure in the circulation passage 4, that is, the head, follows this flow rate change along the characteristic curve of the pump. An operation signal is sent to the driving means 11 so as to do so. Further, the pressure detection means 12 detects the pressure within the circulation passage 4 and feeds it back to the control means 13, which corrects the control error thereby. In this way, the electric pump 1 is operated in a good condition along the above-mentioned characteristic curve that always exhibits maximum efficiency regardless of changes in the liquid volume in the suction side circulation passage 5, and prevents reduction or loss of pumping capacity due to the occurrence of cavitation. can.

Next, a description will be given based on the embodiment shown in FIG. However, equivalent parts common to the embodiment of FIG. 1 are given the same reference numerals and explanations are omitted.

21 is a flow rate detection means arranged in the inflow passage 8;
The control means 2 detects the flow rate of the incoming high temperature liquid.
A signal corresponding to the detected flow rate is sent to 2. A constant flow valve 23 is arranged in the discharge port side circulation passage 4. The constant flow valve 23 maintains the passing flow rate almost constant regardless of the fluid pressure on the primary side. Thus, if the flow rate of the constant flow valve 23 is stored in advance in the control means 23, the flow rate detection means 21 disposed in the inflow passage 8
The amount of liquid flowing through the circulation passage 5 on the suction port side of the electric pump 1 can be estimated simply by the amount of liquid sent from By changing the opening degree of the valve 10 according to the characteristics, the pressure inside the discharge side circulation passage 4 can be changed.

As described above, according to the present invention, the flow rate at the suction port side of the electric pump is detected, and the opening degree of the valve arranged in the pressure passage is changed according to this detected value, so that the pumping height at which the electric pump exhibits maximum efficiency is adjusted. It is possible to provide a combination pump of a jet pump and an electric pump that can be operated according to the characteristics of the amount of pumped liquid and can perform a normal pumping action regardless of fluctuations in the amount of inflowing liquid.

[Brief explanation of the drawing]

FIG. 1 shows a combination pump in one embodiment,
FIG. 2 shows another embodiment of the combination pump. 1 is an electric pump, 2 is a discharge port, 3 is a suction port,
4 and 5 are circulation passages, 6 is a jet pump, and 7 and 2
1 is a flow rate detection means, 8 is an inflow passage, 9 is a pressure feeding passage, 10 is a valve, 11 is a drive means, 12 is a pressure detection means, 13 is a control means, and 23 is a constant flow valve.

Claims (1)

[Claims] 1. Guide the liquid coming out of the discharge port of the electric pump to the nozzle of the jet pump through the circulation passage, also guide the liquid coming out of the diffuser of the jet pump to the suction port of the electric pump, and send the pressurized high-temperature liquid to the suction chamber of the jet pump through the inflow passage. A valve that is opened and closed by a drive means is arranged in a pressure feeding passage branched from the circulation passage, which guides the pressurized liquid in the circulation passage on the discharge port side to the destination. is detected, and the detected flow rate is decreased/
When the flow rate increases, a control signal is sent to the driving means to open/close the valve arranged in the pressure passage so that the opening degree of the valve becomes smaller/larger. A combination pump of an electric pump and a jet pump that allows liquid to flow through a pressure passage while changing according to the characteristic curve of the liquid pumped.