JP2579372Y2 - Liquid fuel supply pump control device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid fuel supply device for supplying liquid fuel to combustion equipment such as a heater and a water heater, and more particularly to a pump control device for the liquid fuel supply device.

[0002]

2. Description of the Related Art This type of liquid fuel supply device is interposed between a main tank storing a large amount of liquid fuel such as petroleum (hereinafter simply referred to as fuel) and one or more combustion devices. A pump for sucking fuel from the main tank into the storage tank and a storage tank for temporarily storing the fuel are provided, and the operation of the pump is controlled by a float switch disposed in the storage tank. .

As shown in FIG. 5, the float switch has a vertically long cylindrical float pipe 101 which is disposed substantially vertically in a storage tank, and which is provided on the outside of the float pipe 101 in a vertical direction. It comprises a ring-shaped float 102 which is movably fitted to the outside. A magnet 103 is built in the float 102, and a magnet 103 is arranged in the float tube 101.
A total of three lead switches S that are turned on and off by separation
1, S2 and S3 are arranged vertically.

A lead switch S1 provided at the bottom of the float tube 101 has a lower limit liquid level L1, and a lead switch S2 provided thereabove has an upper limit liquid level L2 provided at the top. The read switch S3 is used to detect the excess liquid level L3. Specifically, when the liquid level drops to the lower limit liquid level L1 due to fuel supply and the lead switch S1 is turned on, the pump is turned on. When the liquid level rises to the upper limit liquid level L2 by the operation of the pump and the lead switch S2 is turned on, the operation of the pump is stopped so that the liquid level in the storage tank is always at the lower limit. The operation of the pump is controlled so as to be located between the liquid level L1 and the upper limit liquid level L2.

Further, due to the malfunction of the lead switch S2 or the runaway of the pump due to a circuit failure, the liquid level in the storage tank exceeds the upper limit liquid level L2 and rises to the excessive liquid level L3, and the lead switch S3 Is turned on, the normal operation mode is shifted to the abnormal stop mode and the operation of the pump is forcibly stopped. Then, even if the liquid level drops, the pump cannot automatically return. Like that.

[0006]

However, in the above-mentioned conventional liquid fuel supply apparatus, when the fuel pipe connecting the liquid fuel supply apparatus and the combustion equipment is long and the fuel pipe is exposed to the outside, the temperature becomes high. Causes a phenomenon that the air in the fuel pipe expands and fuel flows back into the storage tank.

[0007] The above-described fuel backflow phenomenon occurs at a rate of about once a day. Particularly, when the liquid level in the storage tank is located near the upper limit liquid level L2, the fuel level causes excessive liquid level. The lead switch S3 easily rises to the surface L3 and turns on.

In the conventional apparatus, a lead for detecting the excess liquid level L3
Since the signal of the switch S3 is simply caught as an abnormal signal, there is a problem in that even if the circuit and the pump are operating normally, the mode is shifted to the abnormal stop mode due to the backflow of fuel.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent the pump from being stopped erroneously even when the liquid level in the storage tank reaches an excessive liquid level due to a fuel backflow. An object of the present invention is to provide a pump control device for a liquid fuel supply device.

[0010]

According to the present invention, a pump for sucking liquid fuel into a storage tank and a lower limit liquid level, an upper limit liquid level, and an excess liquid level in the storage tank are detected. A liquid comprising a liquid level sensor and normal operation means for controlling the operation of the pump based on a detection signal from the liquid level sensor so that the liquid level in the storage tank is located between the lower limit liquid level and the upper limit liquid level. In the pump control device of the fuel supply device, there is provided an abnormal stop means for forcibly stopping the operation of the pump only when a detection signal of an excessive liquid level is output from the liquid level sensor during the operation of the pump.

[0011]

According to the present invention, the operation of the pump is forcibly stopped by the abnormal stop means only when the detection signal of the excessive liquid level is output from the liquid level sensor during the operation of the pump. That is, even if the detection signal of the excess liquid level is output from the liquid level sensor when the pump is stopped during the normal operation, the detection signal is ignored and the normal operation is continued.

[0012]

1 to 4 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a liquid fuel supply device, and FIG. 2 is an enlarged longitudinal sectional view of the float switch shown in FIG. FIG. 3 is a block diagram of the pump control device, and FIG. 4 is a flowchart of the pump control.

First, the configuration of the liquid fuel supply device will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a hollow storage tank having a storage chamber 1c therein. An inlet 1a connected to a main tank (not shown) is provided on the bottom surface of the storage tank 1 and a combustion device (not shown). An outlet 1b to be connected is provided. Also, the inlet 1a
A filter chamber 2 is interposed between the storage chamber 1c and the storage chamber 1c, and a filter 2a for removing impurities such as dust from the fuel flowing from the inlet 1a is exchangeably disposed in the filter chamber 2.

Reference numeral 3 denotes a rotary type suction pump which is disposed in the upper opening of the filter chamber 2 so as to close the opening. The pump 3 is an inflow side to which a check valve 4 is connected. Faces the filter chamber 2, and the outflow side and the rotating shaft 3a face the storage chamber 1c.

Reference numeral 5 denotes a motor fixed on the upper surface of the storage tank 1 via a rubber fixing base 6 coaxially with the pump 3. The shaft 5a of the motor 5 projects into the storage room 1c. , And is connected to the rotating shaft 3 a of the pump 3 via the connecting shaft 7. More specifically, a slit for insertion is formed at each end of the shaft 5a and the rotating shaft 3a, and each end of the connection shaft 7 is inserted into the slit to perform connection.

Reference numeral 8 denotes a cylindrical oil cup provided on the inner bottom surface of the storage room 1c so as to surround the pump 3; and 9, a cylindrical oil cup protruding from the inner bottom surface adjacent to the oil cup 8. This is a priming liquid chamber, and the oil cup 8 and the priming liquid chamber 9 are communicated by an inclined passage 10 having a predetermined bottom height.

Numeral 11 denotes a column-shaped priming fluid lead-out float disposed in the priming chamber 9, and a shaft 11a connected to the float 11 projects from the upper surface of the storage tank 1 and projects. It is urged upward by a spring 11c stretched between the operation button 11b fixed to the end and the upper surface of the storage tank 1. Float 1 for priming
Reference numeral 1 is used when the pump 3 is operated in a state where the storage chamber 1c is depleted of fuel. The operation button 11b is depressed, and the priming float 11 is pushed into the priming chamber 9. The fuel stored in the priming chamber 9 can be introduced into the oil cup 8 through the inclined passage 10.

Numeral 12 denotes a cylindrical overflow tube which is erected on the inner bottom surface of the storage room 1c.
The pipe 12 has an upper end opening 12a near the inner upper surface of the storage room 1c.
The lower end opening 12b connected to a main tank (not shown) is located on the bottom surface of the storage tank 1.

Reference numeral 13 denotes an outlet 1 on the inner bottom surface of the storage room 1c.
The outflow chamber 13 is provided with an outflow valve 14 which can open and close the upper opening of the outlet 1b. This outflow valve 1
4, a shaft 14a is slidably fitted into a holder 15 fixed to the upper surface of the storage tank 1, and the upper end thereof is attached to the holder-1.
5 protrudes. Further, the protruding end of the shaft 14a can be pulled up from the position shown in the figure to engage with the upper end of the holder 15, and in this engaged state, the outflow valve 14 is opened and the fuel in the storage chamber 1c is discharged from the outlet 1b. Can spill.

Reference numeral 16 denotes a float switch suspended from the upper surface of the storage room 1c. The float switch 16 has a vertically long cylindrical float tube 16a and a vertical switch outside the float tube 16a. Ring-shaped float 16b which is fitted externally so as to be movable in the direction and whose downward movement is restricted by a stopper 16d.
Consisting of A magnet 16c is built in the float 16b, and a total of three lead switches S which are turned on and off by the approach and separation of the magnet 16c in the float tube 16a.
1, S2 and S3 are arranged vertically.

A lead switch S1 provided at the lowermost part in the float pipe 16a is for detecting the lower limit liquid level L1, and is turned on when the float 16b is in contact with the stopper 16d. Become. The lead switch S2 provided above the lead switch S1 detects the upper limit liquid level L2, and the lead switch S3 provided at the uppermost part detects the excessive liquid level L3. Also, the lead switch S1 and the lead
The lead switch S2 and the lead switch S2 are arranged at a predetermined interval so that the detection areas ST1 and ST2 do not overlap each other. They are arranged so as to partially overlap.

Reference numeral 17 denotes a control board case disposed on the upper surface of the storage tank 1. On the surface of the control board case 17, there is provided a display section 18 for indicating the operation state of the pump.
The display section 18 includes a light emitting diode R1 for displaying a malfunction of the float switch 16 and a failure of the pump 3, a light emitting diode R2 for displaying a normal operation of the pump 3, and a float switch 16 for indicating the normal operation of the pump 3. The light emitting diodes R3 for indicating the malfunction of the circuit and the failure on the circuit are arranged in tandem from the bottom.

Next, a control system of the liquid fuel supply device will be described with reference to FIG. In FIG. 1, reference numeral 21 denotes a control circuit having a microcomputer configuration. The control circuit 21 includes a power switch SW and the above-described lead switch S.
1, S2, S3 and the light emitting diodes R1, R2, R
3 and a drive circuit 22 for driving the pump. The drive circuit 22 includes an AC commercial power supply 22a and a normally open contact R.
A relay 22b having a relay L1 and a relay 22c having a normally closed contact RL2.
22b of the relay 22b based on the pump control signal from
By closing L1, drive power can be supplied to the motor 5.

In this control circuit 21, based on the detection signals of the power switch SW and the lead switches S1, S2, S3, the light emitting diodes R1, R2, R3 and the motor 5 (pump) are stored in accordance with a program stored in the memory. Control the operation of 3).

Next, the operation of the liquid fuel supply device, particularly the operation of the pump, will be described with reference to FIG. First, it is determined whether the lead switch S1 is on based on the turning on of the power switch SW (step 1).

If the liquid level in the storage chamber 1c is lower than the lower limit liquid level L1 when the power switch is turned on, the contact RL of the relay 22b is
1 is closed, the pump 3 is operated to start the fuel suction, the timer T is started, and the light emitting diode is turned on.
The indicator R2 flashes to indicate that the pump 3 is operating normally (steps 2, 3, and 4).

If the liquid level in the storage chamber 1c is between the lower limit liquid level L1 and the upper limit liquid level L2 when the power switch is turned on, the fuel supply causes the liquid level to drop and the lead switch S
It is in a standby state until 1 is turned on.

When the liquid level in the storage chamber 1c rises due to the operation of the pump and the lead switch S1 is turned off, the light emitting diode R2 is changed from blinking to lighting, and the pump 3 operates normally. Is continuously displayed (steps 5 and 6). When the liquid level reaches the upper limit liquid level L2 and the lead switch S2 is turned on, the contact point RL1 of the relay 22b is opened, the operation of the pump 3 is temporarily stopped, and the suction of fuel is interrupted. (Steps 7 and 8) Returning to Step 1, the pump 3 is operated intermittently in the normal operation mode.

If the lead switch S1 is not turned off even after 15 minutes from the start of the operation of the pump 3 in the normal operation mode, a malfunction of the lead switch S1 or a failure of the pump. 3 is considered to have a failure, and
To the first abnormal stop mode of steps 9, 10, and 11, the light emitting diode R1 is turned on,
The contacts RL1 and RL2 of the relays 22b and 22c are opened to forcibly stop the pump 3.

If the lead switch S2 is not turned on after 30 minutes from the start of the operation of the pump 3 in the normal operation mode, the operation of the lead switch S2 may be defective or the pump may not operate. Assuming that a failure has occurred in step 3, step 7
From the second abnormal stop mode of steps 12, 13, and 14
Mode, the light emitting diodes R1, R2, and R3 are all turned on and off, and the contacts R of the relays 22b and 22c are turned on.
The pump 3 is forcibly stopped by opening L1 and RL2.

Further, when the lead switch S3 is turned on during the operation of the pump in the normal operation mode, the lead switch S3 is turned on.
It is considered that runaway has occurred in the pump 3 due to the operation failure of the switch S2 or the failure of the control circuit, and the process shifts from the step 7 to the third abnormal stop mode of the steps 15, 16, 17 and the light emitting diode R3 is turned on, and the contacts RL1 and RL2 of both relays 22b and 22c are opened to forcibly stop the pump 3.

In each of the above-mentioned abnormal stop modes, the contact RL2 of the relay 22c is opened, so that the lead switch S1 is turned on by a subsequent drop in the liquid level, and the contact RL1 of the relay 22b is turned on.
Even if is closed, the pump 3 does not operate again, and in this state, it cannot be automatically restored unless the power switch SW is turned on again.

As described above, according to the present embodiment, the pump 3 is set in the third abnormal stop mode only when the lead switch S3 is turned on during normal operation of the pump.
In other words, when the pump 3 is stopped during normal operation, the fuel flows back into the storage chamber 1c due to a temperature change or the like, and the liquid level rises. Even if the detection signal is issued, the normal operation can be continued ignoring the detection signal, so that an erroneous stop in a state where the pump 3 is operating normally can be reliably prevented to realize an accurate fuel supply. it can.

When the lead switch S1 is turned off and the lead switch S2 is not turned on after a lapse of a predetermined time from the start of the operation of the pump 3 during the normal operation, the first and the first switches are started. Since the operation of the pump 3 can be stopped in the abnormal stop mode 2, the pump 3 can be prevented from continuing to rotate for a long time in a failure state, and damage to the failure can be reduced.

In the above embodiment, when a predetermined detection signal is not transmitted from the float switch after 15 minutes and 30 minutes have elapsed from the start of operation of the pump in the normal operation mode, the operation of the pump is started. Is shown, but the time can be variously changed depending on the capacity of the storage chamber and the suction capacity of the pump. A float switch using a magnet and a lead switch may be replaced by another liquid level sensor having the same detection function.

[0036]

As described above, according to the present invention, when the pump is stopped during normal operation, the fuel flows back into the storage tank due to a change in temperature or the like, and the liquid level rises, resulting in an excessive liquid level. Even if the detection signal is issued, normal operation can be continued ignoring the detection signal, so that erroneous stop during the normal operation of the pump is reliably prevented and accurate fuel supply is realized. it can.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a liquid fuel supply device showing an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of the float switch shown in FIG. 1;

FIG. 3 is a block diagram of a pump control device.

FIG. 4 is a flowchart of pump control.

FIG. 5 is a longitudinal sectional view of a float switch showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Storage tank, 3 ... Pump, 16 ... Float switch, 21 ... Control circuit, L1: Lower limit liquid level, L2 ... Upper limit liquid level, L3 ... Excess liquid level.

Claims (1)

(57) [Scope of request for utility model registration] 1. A pump for sucking liquid fuel into a storage tank, a liquid level sensor for detecting a lower limit liquid level, an upper limit liquid level, and an excess liquid level in the storage tank, respectively, and a detection signal from the liquid level sensor. A pump control device for a liquid fuel supply device comprising: a normal operation means for controlling the operation of the pump so that the liquid level in the storage tank is located between the lower limit liquid level and the upper limit liquid level. Output signal from the
Abnormal stop means for ignoring the operation of the pump and forcibly stopping the operation of the pump only when a detection signal of an excessive liquid level is output from the liquid level sensor at the time of operation of the pump. Pump control device for liquid fuel supply device.