JP2008056316A - Measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring instrument which easily refills an urea water solution and prevents devices from being damaged by a frozen urea water solution unable to be fed as to a measuring instrument for feeding an urea water solution having a relatively high freezing point to an automobile. <P>SOLUTION: This measuring instrument provided with a sheet-like heater (26) for heating the inside of a case (23) and a tank inside heater (32) for heating the liquid in a liquid storage tank (2) is provided with a controller (35) which drives a pump (7) and opens an open/close valve (15) when the temperature signal of an outside temperature sensor (34) falls below a set level, drives the heater (26) when the temperature signal of a case inside sensor (27) and the sensor (34) falls below a set level and drives the tank inside heater (32) when the temperature signal of the sensor (34) and a liquid temperature sensor (33a) becomes below a set level. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a measuring machine that supplies a liquid having a relatively high freezing point, for example, a urea aqueous solution that is a reducing agent that purifies exhaust gas from a diesel engine.

A diesel engine is more frequently used for large trucks because it has higher thermal efficiency, better fuel efficiency, and higher structural durability than a gasoline engine.
However, the diesel engine is a particulate matter (PM) that is concerned about the health damage to the respiratory system and the nitrogen oxide (which is said to be a cause of photochemical smock) due to the structure of the engine and the characteristics of fuel oil. There is a problem that a large amount of exhaust gas containing NOx) and the like is discharged as compared with a gasoline engine.

  As another conventional technique, a technique of reducing particulate oxide and nitrogen oxide by reducing nitrogen oxide to nitrogen and water by injecting urea aqueous solution into exhaust gas and passing through the catalyst is known. (See Patent Document 1).

As automobiles equipped with an exhaust gas purification system using an aqueous urea solution become widespread, there is an increasing demand for a meter for supplying an aqueous urea solution.
Here, the freezing point of the urea aqueous solution is a relatively high temperature of about −11 ° C., although it varies depending on the urea concentration. For this reason, the urea aqueous solution may freeze in a cold region, and the measuring machine may become unusable.

At present, exhaust gas purification systems using urea aqueous solutions are not very popular, and sales volume of urea aqueous solutions is small. For this reason, as a urea aqueous solution supply facility, a storage tank-integrated measuring machine has become the mainstream. In such a storage tank integrated type weighing machine, when the storage tank becomes empty, simple replenishment of an aqueous urea solution is required.
However, in such a storage tank integrated meter, simple replenishment of the urea aqueous solution has not been realized yet.

Here, Patent Document 1 that discloses a technique for reducing nitrogen oxides to nitrogen and water by injecting an aqueous urea solution into exhaust gas and passing through the catalyst, thereby reducing particulate matter and nitrogen oxides. No solution is disclosed for the above-mentioned problems.
JP 2004-132286 A

  The present invention has been made in view of the above, and in a weighing machine that supplies a urea aqueous solution having a relatively high freezing point to an automobile, the urea aqueous solution freezes, making it impossible to supply the liquid or damaging the device. The object of the present invention is to provide a weighing machine that can be easily replenished with an aqueous urea solution.

  According to the present invention, a device storage case (3) is provided in a liquid storage tank (2), and a liquid supply pipe (4) inserted into the liquid storage tank (2) is introduced into the device storage case (3). A pump (7) and a flow meter (11) are installed in the pipe (4), and a liquid supply hose (13) is connected to the liquid supply pipe (4) led out of the device storage case (3). In the weighing machine (1) provided with a liquid supply nozzle (12) at the tip of (13) and provided with a case (23) for storing the liquid supply nozzle (12), one end is the tip of the liquid supply hose (13). The tube (14) with the other end opened to the liquid supply pipe (4) on the upstream side of the pump (7) is arranged in the liquid supply hose (13) and opened and closed to the tube (14). A sheet heater (26) for interposing a valve (15) and heating the inside of the case (23) and the liquid in the liquid storage tank (2) are heated. And an external air temperature sensor (34), a case internal temperature sensor (27), and liquid temperature sensors (33a, 33b). The temperature signal of the external air temperature sensor (34) is less than a certain level. Then, the pump (7) is driven to open the on-off valve (15). When the temperature signals of the outside air temperature sensor (34) and the case internal temperature sensor (27) become below a certain level, the sheet heater (26) is driven to A control device (35) is provided for driving the heater (32) in the tank when the temperature signals of the air temperature sensor (34) and the liquid temperature sensor (33a) become below a certain level (Claim 1).

  In the present invention, it is preferable to provide a check valve (9) on the discharge side of the pump (7) of the liquid supply pipe (4).

  In the present invention, it is preferable that an orifice (5) be interposed in a region between the pump (7) and the liquid storage tank (2) of the liquid supply pipe (4).

  And the liquid level sensor (31) which detects the liquid level in the liquid storage tank (2) is provided, and the opening (4a) in the liquid storage tank (2) of the liquid supply pipe (4) is the heater in the tank. Preferably, it is provided above (32) and below the lower limit detector (31a) of the liquid level sensor (31).

  In carrying out the present invention, the liquid supply pipe (4) is provided with an orifice (5), a switching valve (6), a pump (7), a check valve (9), a filter (10), and a flow meter (11). When the liquid supply pipe (4) on the downstream side of the check valve (9) is connected to the switching valve (6) via the bypass pipe (16), and the supply hose (20) is connected to the switching valve (6) The flow path connecting the replenishment hose (20) and the pump (7) and the flow path connecting the bypass pipe (16) and the liquid storage tank (2) are formed (in the switching valve 6). preferable.

The effects of the present invention having the above-described configuration are listed below.
(1) Since the liquid in the liquid supply hose is circulated when the temperature is low, the liquid is not frozen, and the weighing machine can be prevented from being unusable or damaged due to freezing.
(2) Since the tube for circulating the liquid is disposed in the liquid supply hose, the operability of the liquid supply hose is not impaired.
(3) Since the sheet heater for heating the inside of the case for storing the liquid supply nozzle is provided, the liquid in the liquid supply nozzle freezes or the metal part of the liquid supply nozzle sticks to the hand of the worker. There is nothing. Moreover, since it is a sheet-like heater, temperature control and waterproofing treatment are easy and safety is high.
(4) Since the tank heater for heating the liquid in the liquid storage tank is provided, the liquid in the liquid storage tank does not freeze.
(5) Since the tube is connected to the liquid supply pipe on the upstream side of the pump, the liquid in the tube is sucked by the pump, the circulation of the liquid is promoted, and the antifreezing effect is improved.
(6) If a check valve is provided on the downstream side of the pump, the inside of the pump is always filled with liquid, and even if a centrifugal pump is used, liquid can be fed without any trouble. Moreover, it is possible to prevent air from flowing downstream from the check valve, and to prevent the liquid mixed with air from being metered and sold.
(7) If an orifice is provided in the liquid supply pipe, the bypass pipe is maintained at a positive pressure when the liquid is replenished, and the liquid in the liquid supply hose does not flow backward.
(8) If the opening of the liquid supply pipe in the liquid storage tank is provided above the heat generating part of the heater in the tank, the heat generating part is always located in the liquid and is not exposed to air, which is safe.
(9) If an opening of the liquid supply pipe in the liquid storage tank is provided below the lower limit detection part of the liquid level sensor, a predetermined amount of liquid can be supplied even after notifying that the liquid level has reached the lower limit. Therefore, there is no possibility of causing trouble in the liquid supply work to the automobile. And there are few business troubles.
(10) If a switching valve is provided in the liquid supply pipe and a replenishing hose is connected to the switching valve so that a replenishing flow path is formed, the liquid can be easily replenished.
(11) If a filter is provided on the upstream side of the flow meter, the flow meter is prevented from being damaged by foreign matter in the liquid, and the vehicle-side equipment to be supplied is prevented from being damaged by the foreign matter. The

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1 and FIG. 2, the urea aqueous solution meter 1 provided with an antifreezing function is composed of a lower liquid storage tank 2 and a device storage case 3 provided above the liquid storage tank 2. In the liquid storage tank 2, an aqueous urea solution is stored.

The liquid supply pipe 4 inserted into the liquid storage tank 2 is introduced into the device storage case 3, and the liquid supply pipe 4 has an orifice 5, a switching valve 6, a pump 7, an air vent 8, a check valve 9, a filter. 10 and a flow meter 11 are interposed.
The liquid supply pipe 4 is led out of the device storage case 3 and connected to the liquid supply hose 13. A liquid supply nozzle 12 is provided at the tip of the liquid supply hose 13.

As shown in FIG. 3, a tube 14 is inserted in the liquid supply hose 13. The distal end of the tube 14 is opened near the distal end of the liquid supply hose 13 (reference numeral 14a in FIG. 3).
In FIG. 1 again, the rear end of the tube 14 joins the liquid supply pipe 4 on the upstream side of the pump 7. An electromagnetic on-off valve 15 is interposed in the tube 14.

A bypass pipe 16 is connected to the liquid supply pipe 4 on the downstream side of the check valve 9, and the bypass pipe 16 is connected to the switching valve 6.
The liquid supply pipe 4 on the downstream side of the check valve 9 and the liquid supply pipe 4 on the upstream side of the pump 7 are connected by a side pipe 17. A relief valve 18 is interposed in the side pipe 17.
An air vent 8 is interposed in a region between the pump 7 and the check valve 9. An air pipe 19 is connected to the air vent 8, and the air pipe 19 is connected to the liquid storage tank 2.

  The switching valve 6 normally connects the liquid supply pipe 4 to the pump 7 side to form a flow path connecting the liquid storage tank 2 and the pump 7. When the coupling 21 of the urea solution replenishment hose 20 is connected, a flow path connecting the replenishment hose 20 and the pump 7 is formed, and a flow path connecting the bypass pipe 16 and the liquid storage tank 2 is formed. The switching valve 6 is switched to form.

  The orifice 5 is provided in order to maintain the pressure in the bypass pipe 16 at a positive pressure when the replenishment hose 20 is connected to the switching valve 6 and the aqueous urea solution is replenished to the liquid storage tank 2. In other words, the orifice 5 is provided to prevent the urea aqueous solution in the liquid supply pipe 4 and / or the liquid supply hose 13 from flowing backward and emptying the pipe.

  The check valve 9 is for always filling the inside of the pump 7 with a urea aqueous solution. Especially when a centrifugal pump is used, the urea aqueous solution in the pump 7 is prevented from falling off and difficult to feed. is doing.

  The air vent 8 interposed between the pump 7 and the check valve 9 separates the air contained in the urea aqueous solution discharged from the pump 7 from the urea aqueous solution, and passes through the air pipe 19. Is provided to return to the liquid storage tank 2. And the situation where the urea aqueous solution containing air is metered and sold is prevented by separating the air from the urea aqueous solution.

  The relief valve 18 is interposed in the side pipe 17 and is provided for releasing the pressure when the discharge side of the pump 7 becomes abnormally high pressure, so that each device on the downstream side of the pump 7 and the pump 7 is provided. Is protected from abnormally high pressure.

  The filter 10 is interposed in the liquid supply pipe 4 on the downstream side of the check valve 9, removes dust in the urea aqueous solution, and replaces the flow meter 11 and each device of the automobile to which the urea aqueous solution is supplied with the urea aqueous solution. It is provided to protect against various foreign matters (dust and others) mixed in.

In FIG. 1, a case 23 having a door 22 is disposed on the left side of the device storage case 3, and a nozzle hook 24 is provided in the case 23.
A nozzle switch 25 is provided on the nozzle hook 24, and the nozzle switch 25 is turned on / off by the liquid supply nozzle 12 that is hooked on and off the nozzle hook 24.

A sheet heater 26 is provided on the inner wall surface of the case 23. This is because the liquid supply nozzle 12 is warmed by the heat generated by the sheet heater 26 and the urea aqueous solution in the liquid supply nozzle 12 is prevented from freezing.
The sheet heater 26 is provided with a case internal temperature sensor 27, and the case internal temperature sensor 27 prevents abnormal heat generation of the sheet heater 26.

  In the device storage case 3, a tank heater 32 for warming the liquid in the liquid storage tank 2, a liquid temperature sensor 33 a for detecting the liquid temperature in the liquid storage tank 2, and another liquid temperature detecting sensor for detecting an excessive rise in the liquid temperature. A temperature sensor 33b and a liquid level switch 31 for detecting the lowest liquid level and the highest liquid level in the liquid storage tank 2 are provided.

The tank heater 32 is provided in the liquid storage tank 2. The urea aqueous solution in the liquid storage tank 2 is warmed by the tank heater 32 to prevent freezing.
The tank is provided with a liquid temperature sensor 33a that detects an abnormality in the liquid temperature, and the tank heater 32 heats the urea aqueous solution in the tank 2 more than necessary by the liquid temperature sensor 33b that detects the liquid temperature or higher. And abnormal heat generation is prevented.

The tank heater 32 is located below the lower end opening 4 a of the liquid supply pipe 4. By positioning the in-tank heater 32 below the lower end opening 4a of the liquid supply pipe 4, the in-tank heater 32 is not exposed to the air, and the heater 29 is prevented from being damaged by so-called “air blowing”. .
Further, the lowest liquid level detection part 31 a of the liquid level sensor 31 is located above the lower end opening 4 a of the liquid supply pipe 4. Since the minimum liquid level detection unit 31a is positioned above the lower end opening 4a of the liquid supply pipe 4, at least one unit (urea) is detected even after detecting that the liquid level of the urea aqueous solution has decreased to the minimum liquid level. Since the urea aqueous solution can be supplied to a plurality of vehicles if the vehicle has a small tank capacity of the aqueous solution, the urea aqueous solution is reliably supplied to the vehicle.

  The device storage case 3 is provided with an outside air temperature sensor 34 that detects the air temperature, a control device 35, an operation panel 36, a display device 37, and a notification device 38.

As shown in FIG. 4, the flow meter 11, the nozzle switch 25, the case internal temperature sensor 27, the liquid temperature sensors 33 a and 33 b, the liquid level switch 31, the outside air temperature sensor 34, and the operation panel 36 are connected to the control device 35. Has been.
The control means 39 of the control device 35 that receives signals from the flow meter 11, the nozzle switch 25, the case internal temperature sensor 27, the liquid temperature sensors 33a and 33b, the liquid level switch 31, the outside air temperature sensor 34, and the operation panel 36 is a drive means. Control signals are output to the pump 7, the on-off valve 15, the sheet heater 26, the in-tank heater 32, the display 37, and the alarm 38 via 40, 41, 42, 43, 44 and 45 (FIG. 4). It is configured as follows.

Next, control in the illustrated embodiment will be described based on the flowcharts of FIGS.
FIG. 5 is a flowchart showing a control mode of the sheet heater 26.
In FIG. 5, it is determined whether or not the temperature signal of the outside air temperature sensor 34 is equal to or lower than a certain temperature T1 (for example, −3 ° C.) (step ST1).

If the temperature signal of the outside air temperature sensor 34 is equal to or lower than a certain temperature T1 (for example, −3 ° C.) (Yes in step ST1), is the case inner temperature sensor 27 in the case 23 equal to or smaller than the certain temperature T2 (for example, 35 ° C.)? It is determined whether or not (step ST2).
If the case internal temperature sensor 27 in the case 23 is equal to or lower than a certain temperature T2 (for example, 35 ° C.) (Yes in step ST2), the control of the outside air temperature sensor 34 and the control device 35 that receives the temperature signals of the case internal temperature sensor 27 is controlled. The means 39 drives the sheet heater 26 via the drive means 42 (step ST3).

Then, it is determined whether or not the inside of the case 23 is heated to a predetermined temperature T2 (for example, 35 ° C.) or higher (step ST4).
When the inside of the case 23 is heated to a predetermined temperature T2 (for example, 35 ° C.) or higher (step ST4 is Yes), the driving of the sheet heater 26 is stopped (step ST6). On the other hand, even if the inside of the case 23 is not warmed to a certain temperature T2 (for example, 35 ° C.) or higher (No in step ST4), the outside air temperature becomes a certain temperature T3 (for example, 0 ° C.) or more (step ST5). Then, the driving of the sheet heater 26 is stopped (step ST6).

As a result of performing the control as shown in FIG. 5, the inside of the case 23 housing the liquid supply nozzle 12 is always kept at a certain room temperature or higher. Therefore, the urea aqueous solution in the liquid supply nozzle 12 does not freeze.
In addition, when the worker touches the metal part of the liquid supply nozzle 12 with his bare hand during cold weather, the metal part can be prevented from sticking to his bare hand.

FIG. 6 is a flowchart showing a control mode of the tank heater 29.
In FIG. 6, it is determined whether or not the temperature signal of the outside air temperature sensor 34 is equal to or lower than a certain temperature T1 (for example, −3 ° C.) (step ST11). If the temperature signal of the outside air temperature sensor 34 is equal to or lower than a certain temperature T1 (for example, −3 ° C.) (step ST11 is Yes), whether or not the temperature signal of the liquid temperature sensor 33a is equal to or smaller than the certain temperature T5 (for example, −1 ° C.). Is determined (step ST12).
When the temperature signal of the liquid temperature sensor 33a is equal to or lower than a certain temperature T5 (for example, -1 ° C.) (Yes in step ST12), the control of the control device 35 that receives the temperature signals of the outside air temperature sensor 34 and the liquid temperature sensor 33a. The means 39 drives the tank heater 32 by the drive means 43 (step ST13).

After driving the tank heater 32, it is determined by the liquid temperature sensor 33a whether the liquid temperature of the urea aqueous solution becomes a constant temperature (for example, 3 ° C.) (step ST14). When the liquid temperature reaches a certain temperature T6 (eg, 3 ° C.) (Yes in step ST14), the driving of the tank heater 32 is stopped (step ST16).
On the other hand, when the liquid temperature is not the constant temperature T6 (eg, 3 ° C.) (No in step ST14), it is determined whether or not the outside air temperature is equal to or higher than the constant temperature T3 (eg, 0 ° C.) (step ST15). ). When the outside air temperature becomes equal to or higher than a certain temperature T3 (for example, 0 ° C.) (Yes in step ST15), the driving of the in-tank heater 32 is stopped (step ST16).

When the liquid temperature sensor 33a breaks down or in other emergency, control as shown in FIG. 7 is performed.
In FIG. 7, first, it is determined whether or not the tank heater 32 is driven (step ST17). If the tank heater 32 is driven (Yes in step ST17), the liquid temperature in the tank 2 is detected by the liquid temperature sensor 33b, and whether the liquid temperature is increased to a certain temperature T7 (for example, 35 ° C.) or higher. Judgment is made (step ST18).
When the liquid temperature in the tank 2 rises to a certain temperature T7 (for example, 35 ° C.) or more (Yes in step ST18), the alarm 38 is driven to display, for example, “The heater is abnormally heated”. Or informing that the lamp blinks, etc., and stopping the tank heater 32 (step ST19).
By performing the control shown in FIGS. 6 and 7, the urea aqueous solution in the liquid storage tank 2 is always kept at a liquid temperature higher than a certain level, and the urea aqueous solution is prevented from freezing.

FIG. 8 is a flowchart showing control related to the circulation of the liquid.
In FIG. 8, it is determined whether or not the temperature signal of the outside air temperature sensor 34 is equal to or lower than a certain temperature T1 (for example, −3 ° C.) (step ST21). If the temperature signal of the outside air temperature sensor 34 is equal to or lower than a certain temperature T1 (for example, −3 ° C.) (Yes in step ST21), the control means 39 of the control device 35 that has received this temperature signal is not in liquid supply and is not nozzle It is confirmed whether or not the switch 25 is off (step ST22).
If the nozzle switch 25 is off (step ST22 is Yes), the opening / closing valve 15 is opened by the driving means 41, and the pump 7 is driven by the driving means 40 (step ST23).

When the pump 7 is driven, the liquid in the liquid storage tank 2 is supplied from the liquid supply pipe 4, the orifice 5, the switching valve 6, the pump 7, the air vent 8, the check valve 9, the filter 10, the flow meter 11, the supply Via the liquid hose 13, the tube 14, and the open / close valve 15, the liquid is returned to the liquid supply pipe 4 on the upstream side of the pump 7 and circulated.
By circulating the urea aqueous solution in the liquid supply pipe 4 and the liquid supply hose 13, freezing of the urea aqueous solution in the liquid supply pipe 4 and the liquid supply hose 13 can be prevented.

When the aqueous urea solution circulates, a flow rate pulse signal is input from the flow meter 11 to the control device 35. The control means 39 calculates an instantaneous flow rate (L / min) based on the flow rate pulse signal.
In step ST24, it is determined whether or not the instantaneous flow rate (L / min) is within a certain range. If the instantaneous flow rate (L / min) is within the certain range (step ST24 is Yes), the outside air temperature sensor 34 It is determined whether or not the measured outside air temperature is equal to or higher than a certain temperature T3 (for example, 0 ° C.) (step ST25).
If the outside air temperature is equal to or higher than a certain temperature T3 (for example, 0 ° C.) (Yes in step ST25), the urea aqueous solution in the liquid supply pipe 4 and the liquid supply hose 13 is not likely to freeze. The valve 15 is closed (step ST26). Thereby, the weighing machine 1 returns to the basic state.

In step ST24, when the instantaneous flow rate is below a certain level, it is determined that there is a failure such as freezing in the flow path. On the other hand, when the instantaneous flow rate is above a certain level, it is determined that there is a problem such as the liquid supply nozzle 12 being open. In any case (when the instantaneous flow rate is out of a certain range: when step ST24 is No), the alarm 38 is driven by the driving means 45, for example, “the flow path is frozen” or “liquid leakage” The pump 7 is stopped (step ST27).
This prevents the urea aqueous solution from circulating in the abnormal state.

FIG. 9 is a flowchart showing a mode in which an aqueous urea solution is supplied to an automobile.
In FIG. 9, the door 22 of the case 23 is opened to remove the liquid supply nozzle 12 from the nozzle hook 24, and it is determined whether or not an ON signal of the nozzle switch 25 is input to the control device 35 (step ST31). When the ON signal of the nozzle switch 25 is input to the control device 35 (Yes in step ST31), the control unit 39 drives the pump 7 by the driving unit 40 (step ST32).

  The urea aqueous solution in the liquid storage tank 2 is supplied from a liquid supply pipe 4, an orifice 5, a switching valve 6, a pump 7, an air vent 8, a check valve 9, a filter 10, a flow meter 11, a liquid supply hose 13, and a liquid supply nozzle 12. Then, the liquid is supplied to a urea aqueous solution storage tank of an automobile (not shown).

The amount of liquid supplied to a vehicle (not shown) is measured by the flow meter 11, and if the flow rate pulse of the flow meter 11 is input to the control device 35 (Yes in step ST33), the amount of liquid supplied is calculated by the control means 39, and the drive means 44 is displayed on the display 37 (step ST34).
When the liquid supply is completed, the liquid supply nozzle 12 is returned to the nozzle hook 24 and an OFF signal of the nozzle switch 25 is input to the control device 35 (Yes in step ST35), the pump 7 is stopped (step ST36).

FIG. 10 shows the control when the urea aqueous solution liquid level in the liquid storage tank 2 reaches the lower limit.
In the flowchart of FIG. 10, it is determined whether or not the liquid level (liquid level) of the urea aqueous solution in the liquid storage tank 2 is lowered and the lower limit detection unit 31a of the liquid level sensor 31 is turned on (step ST41). When the liquid level (liquid level) of the urea aqueous solution is lowered and the lower limit detection unit 31a of the liquid level sensor 31 is turned on (Yes in step ST41), the control of the control device 35 that has received the lower limit signal from the liquid level sensor 31. The means 39 drives the alarm 38 by the driving means 45, and the alarm 38 notifies, for example, “Urea aqueous solution is low. Please replenish” or “E” on the display. Is displayed. Then, the measurement of the liquid supply amount after the notification starts (step ST42).

Then, the liquid supply is continued after the notification, and when the liquid supply amount after the notification reaches a certain amount (for example, 60 L) (Yes in step ST43), the pump 7 is stopped and the notification device 38 notifies the liquid supply impossibility. (Step ST44).
Thus, even after the fact that the urea aqueous solution liquid level in the liquid storage tank 2 has reached the lower limit, the urea aqueous solution can be supplied up to a certain amount (for example, 60 L), so the supply to the vehicle is interrupted. There is no fear of it. For this reason, there is little trouble in sales.

  Before being notified in step ST42 and supplying a certain amount (for example, 60L) (No in step ST43), the urea aqueous solution is supplied into the liquid storage tank 2, the liquid level rises, and the lower limit detection unit 31a is activated. When turned off (Yes in step ST45), the process returns to step S41 again.

FIG. 11 is a control flowchart when the urea aqueous solution is replenished into the liquid storage tank 2.
Here, with reference to FIG. 1, the operation | work which supplies urea aqueous solution in the liquid storage tank 2 is demonstrated.
In FIG. 1, the coupling 21 of the supply hose 20 is connected to the switching valve 6 and the supply switch of the operation panel 36 is operated. By connecting the coupling 21 to the switching valve 6, a flow path that connects the replenishment hose 20 and the pump 7 is formed, and a flow path that communicates from the discharge side of the pump 7 to the liquid storage tank 2 via the bypass pipe 16. Is formed.

Such work will be described with reference to FIG. 11. First, it is determined whether or not the supply switch of the operation panel 36 has been operated (step ST51). When the supply switch of the operation panel 36 is operated (Yes in step ST51), the control means 39 of the control device 35 that receives the supply signal from the operation panel 36 drives the pump 7 by the drive means 40 (step ST52). .
When the pump 7 is driven, the urea aqueous solution from the replenishing hose 20 passes through the switching valve 6, the pump 7, the air vent 8, the check valve 9, the bypass pipe 16, the switching valve 6, the orifice 5, and the liquid supply pipe 4. Then, it is replenished into the liquid storage tank 2 (see FIG. 1).
When the aqueous urea solution is supplied to the liquid storage tank 2, the inside of the bypass pipe 16 is maintained at a positive pressure by the orifice 5, and the aqueous urea solution in the liquid supply hose 13 is prevented from flowing backward.

In FIG. 11 again, after the pump 7 is driven, it is determined whether or not the liquid level of the liquid storage tank 2 has risen due to replenishment and the upper limit detection unit 31b of the liquid level sensor 31 has been turned on (step ST53). When the upper limit detection unit 31b is turned on (Yes in step ST53), it is determined that the replenishment is finished, and the pump 7 is stopped (step ST55).
On the other hand, even when the upper limit detection unit 31b is not turned on (No in Step ST53), when the supply switch of the operation panel 36 is returned (Yes in Step ST54), the pump 7 is stopped (Step ST55).
And if the coupling 21 is removed from the switching valve 6, the flow path of the liquid supply pipe 4 and the pump 7 will be formed, and it will return to a normal state.

It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.
For example, in the illustrated embodiment, the example of a meter that supplies a urea aqueous solution has been described. However, the meter can be similarly implemented if it is a meter that handles a liquid having a relatively high freezing point in a cold region.

The schematic diagram which shows the structure of the weighing machine which concerns on embodiment of this invention. The front view of a weighing machine. The perspective view of a part of liquid supply hose. The block diagram which shows the structure regarding control of a weighing machine. The flowchart of control of a sheet-like heater. The control flowchart of the heater in a tank. Flowchart showing control different from that in FIG. 6 for the heater in the tank Flow chart of liquid circulation control. The control flowchart of liquid supply. The control flowchart when the liquid in a liquid storage tank becomes a minimum. The control flowchart in the case of replenishing a liquid into a liquid storage tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Metering machine 2 ... Liquid storage tank 3 ... Equipment storage case 4 ... Liquid supply pipe 5 ... Orifice 6 ... Switching valve 7 ... Pump 8 ... Air vent DESCRIPTION OF SYMBOLS 9 ... Check valve 10 ... Filter 11 ... Flow meter 12 ... Liquid supply nozzle 13 ... Liquid supply hose 14 ... Tube 15 ... On-off valve 16 ... Bypass pipe 17.・ ・ Side pipe 18 ・ ・ ・ Release valve 19 ・ ・ ・ Air pipe 20 ・ ・ ・ Supply hose 21 ・ ・ ・ Coupling 22 ・ ・ ・ Door 23 ・ ・ ・ Case 24 ・ ・ ・ Nozzle hook 25 ・ ・ ・ Nozzle Switch 26 ... Sheet heater 27 ... Case internal temperature sensor 31 ... Liquid level sensor 32 ... Tank internal heater 33a, 33b ... Liquid temperature sensor 34 ... Outside air temperature sensor 35 ... Control device 36... Operation panel 37. ... Indicator 39 ... Control means 40, 41, 42, 43, 44, 45 ... Drive means

Claims (4)

A device storage case is provided on the liquid storage tank, a liquid supply pipe inserted into the liquid storage tank is introduced into the device storage case, a pump and a flow meter are interposed in the liquid supply pipe, and the liquid storage pipe is led out of the device storage case. Connect the liquid supply hose to the liquid supply pipe, provide the liquid supply nozzle at the tip of the liquid supply hose, and in the weighing machine provided with the case for storing the liquid supply nozzle, open one end at the tip of the liquid supply hose, A tube with the other end opened to the liquid supply pipe upstream of the pump is disposed in the liquid supply hose, an open / close valve is interposed in the tube, and the heater in the sheet heater and the storage tank for heating the inside of the case A tank heater that warms the liquid is provided, and an outside air temperature sensor, a case inside temperature sensor, and a liquid temperature sensor are provided.When the temperature signal of the outside air temperature sensor falls below a certain level, the pump is driven to open the on-off valve. The temperature signals of the air temperature sensor and the case internal temperature sensor are below a certain level. When it comes to driving a sheet heater, the temperature signal of the outside air temperature sensor and the liquid temperature sensor is constant less weighing machine, characterized in that a control device for driving a heater in the tank.   2. The measuring instrument according to claim 1, wherein a check valve is provided on the discharge side of the pump of the liquid supply pipe.   3. The measuring device according to claim 1, wherein an orifice is interposed in a region between the pump of the liquid supply pipe and the liquid storage tank.   A liquid level sensor for detecting the liquid level in the liquid storage tank is provided, and the opening in the liquid storage tank of the liquid supply pipe is provided above the heater in the tank and below the lower limit detection part of the liquid level sensor. The measuring device according to any one of claims 1 to 3.

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