JPS62248919A - Liquid fuel sensor - Google Patents

Abstract

PURPOSE:To make it possible to detect the fuel flow rate with certainty and high accuracy by obtaining the amount of fuel consumption in a burner from the change in the liquid level in a detection tank when a valve device is closed and controlling the fuel consumption to a specified amount of combustion. CONSTITUTION:A valve control section 27 output a signal to close a valve device 15 periodically, and when the valve device 15 is closed, the liquid level in a detection tank 10 drops. With this drop a liquid level sensor 18 calculates the time for the liquid level to pass from L1 and to reach L2 to obtain fuel consumptions of a burner 14. A fuel correction section 29 compares the amount of combustion by the burner 14 at present calculated by a fuel calculation section 28 with a target amount of combustion and outputs negative feedback signal to a pump drive section 17 so that the amount of combustion becomes equal to the target amount of combustion. With this arrangement, even if there is a fluctuation of operation in a pump 11, the amount of combustion is controlled to the target value. With this constitution stable combustion continues and there is no fear of incomplete combustion, fire, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for detecting the fuel flow rate of a combustor that burns liquid fuel such as kerosene.

BACKGROUND ART Conventionally, various means for detecting the flow rate of fluid, such as those that measure fluid pressure and those that rotate water turbines (windmills), have been proposed and put into practical use. However, these conventional devices have problems such as complicated sensing means and high costs for application to household appliances such as fan heaters. There is a device that makes this possible, as disclosed in Japanese Patent Laid-Open No. 53-43244, which cools a heated resistor with a fluid and detects a change in the resistance value of the resistor. As shown in Fig. 5, this consists of a pair of sensors 1°3...
- Insert the sensor 2 into the fluid passage 3, and apply electricity from the external terminals 4 and 5 to cause the sensors 1 and 2 to self-heat with a constant current. Here, the sensor 1 is installed in a fluid flow path, and the sensor 2 is installed in a portion 7 where no fluid flows due to a partition wall 6 provided in the fluid flow path. With the above configuration, when the fluid flows from the direction of the arrow in the figure, the sensor 1 radiates heat due to the flow. Utilizing the fact that the amount of heat radiation is proportional to the flow velocity of the fluid, the amount of heat radiation is measured by the resistance value of the sensor 1. On the other hand, since there is no fluid flow in sensor 2, the temperature of the fluid is detected. Therefore, the flow rate of the fluid is detected based on the temperature difference between the sensor 1 and the sensor 2.

Problems to be Solved by the Invention However, there are several problems when using the above configuration for detecting the flow rate of liquid fuel according to the present invention.

One is that it is advantageous to set the temperature of the sensors 1 and 2 high in order to improve detection accuracy, but if the sensing fluid is flammable fuel, high temperatures cannot be used because it is dangerous. Therefore, it is easily influenced by the fluid temperature, and therefore temperature guarantee is important. From the above, it is necessary to make the temperature characteristics of the sensors 1 and 2 and the variation among each sensor small. Also, because the sensor temperature is low, detection at low flow rates is difficult.

Another problem is that liquid fuel is generally supplied by a fuel pump or the like, and the flow is not uniform but pulsating. For this reason, when applied to detecting the flow rate of liquid fuel as in the present invention, there is a problem in that highly accurate detection is difficult because the influence of pulsating flow causes errors.

Means for Solving the Problems The liquid fuel detection device of the present invention comprises: a detection tank with a fixed volume into which liquid fuel in the fuel tank is introduced; a valve device that opens and closes a fuel passage communicating the detection tank and the fuel tank;
A fuel pump that supplies fuel to the combustor is provided downstream of this valve device, and a liquid level sensor that detects changes in the internal fuel liquid level is provided in the detection tank. , a fuel calculation unit that calculates the fuel consumption of the combustor based on the output of the liquid level sensor at 5...-7 when the valve device closes the fuel passage, and a fuel correction unit that controls the drive amount of the fuel pump according to this output. The controller is configured to include a controller inside.

According to the above-described configuration, the present invention periodically closes the valve device and calculates the fuel consumption amount of the combustor from the change in the liquid level in the detection tank sucked out by the fuel pump when the valve device is closed. This is to provide feedback control to the fuel pump so that the amount of fuel is maintained.

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, fuel in a fuel tank 8 is led to a detection tank 10 through a passage 9, and the fuel in the detection tank 10 is sent to a vaporizer 12 by a fuel pump 11, where a blower 1
It is mixed with the combustion air from 3 and burned in the burner 14. 1
Reference numeral 5 indicates a valve device such as a solenoid valve provided in the fuel passage 9.

16 is a cartridge tank that supplies fuel to the fuel tank 8. The fuel pump 11 is an electromagnetic pulse pump that operates in response to a pulse output from a pump drive unit 17.

The fuel pump 11 may have a different configuration or may be a supply means other than a pump. Here, the detection tank 10 is provided with a liquid level sensor 18 that detects changes in the internal liquid level. The liquid level sensor 18 may have the configuration shown in FIG. 2, for example. In FIG. 2, a light-emitting element 20.21 and a light-receiving element 22 are provided opposite to each other with a transparent pipe 19 in between.
．． 23 is configured to detect whether the liquid level is above or below Ll or above or below L2 based on the difference in light transmittance depending on the presence or absence of the liquid 24 inside. The liquid level sensor may also be one that uses a float or one that uses ultrasonic waves.

In FIG. 1, the controller 25 includes a liquid level detection section 26 that detects the liquid level based on a signal from the liquid level sensor 18, and a valve control section 27 that drives the valve device 15 to open and close. The valve control unit 27 periodically outputs a signal to close the valve device 15. When the valve device 15 closes, the fuel pump 1
1, the liquid level in the detection tank 10 decreases. As a result, the fuel consumption of the burner 4 is determined by the liquid level sensor 8 measuring the time from when the liquid level passes through Ll to reaching L2. The calculation unit 28 performs the above calculations. The combustion amount is determined by the calorific value per unit weight of the fuel, the specific gravity, and the volume between the liquid levels L1 and L2 of the detection tank 10.
It is calculated by measuring the time of l and L2. It may be corrected by the fuel temperature if necessary. When the current combustion amount of the burner 4 is calculated by the fuel calculation unit 28, the fuel correction unit 29 calculates
This value is compared with the target combustion amount, and a negative feedback signal is output to the pump drive unit 17 so that the combustion amount matches the target combustion amount. Thereby, even if there are variations in the pump 11, the combustion amount is controlled to the target combustion amount.

When the valve control unit 27 detects that the liquid level of the liquid level sensor 8 has become below L2, it opens the valve device 15 and supplies the fuel in the fuel tank 8 to the detection tank 10. 30 is an air hole of the detection tank 10. The valve control unit 27 repeatedly opens and closes the valve device 15 as described above, and controls the burner 14.
Find the amount of combustion.

Here, when the fuel in the cartridge tank 16 runs out and the liquid level does not rise above L1 when the valve device 15 is opened, the notification section 31 notifies that the remaining fuel is low. Further, when the fuel decreases further and the liquid level when the valve device 15 is opened becomes below L2, it is determined that the fuel is running out and a signal is output to a reset section (not shown) that stops combustion.

The above determination is made by the remaining fuel determining section 32.

Further, the motor control section 33 outputs a signal for controlling the amount of air blown from the blower 13 so that combustion is performed at an optimal air-fuel ratio according to the amount of combustion of the burner 14 determined by the fuel calculation section 28 . The motor control unit 33 may be configured to control the rotation speed of the blower motor of the blower 13 or may be configured to control the passage resistance of the blower passage 34.

FIG. 3 shows another embodiment, and the same functional parts as those in FIG. 1 are marked with the same numbers. Unlike the configuration shown in FIG. 1, the fuel pump 11 is provided separately from the detection tank 10. With this configuration, the size of the detection tank 10 can be reduced, and the causes of variations in the volume of the detection tank 10 are reduced, resulting in high accuracy.

FIG. 4 shows a flowchart when the controller 25 that performs the above operations is configured with a microcomputer. 1st
The same numbers are marked on the flows corresponding to each functional section in the controller 25 in the figure.

With the above configuration, the motor control unit 33 always maintains stable combustion at the optimal air-fuel ratio for the current combustion amount.
There is no need to worry about incomplete combustion or misfires.

In this case, it is also possible to have a configuration in which the fuel correction section 29 is omitted.

Further, the remaining fuel determination unit 32 determines the remaining fuel in the fuel tank 8, and appropriate controls such as refueling notification and combustion stop can be performed. Further, a liquid level detector such as a float, which is conventionally provided in the fuel tank 8 for determining the remaining fuel, is no longer necessary.

Further, it can be determined that there is no drop in the liquid level when the valve device 15 has failed and remains open.

Furthermore, if the valve remains closed, the liquid level will drop below L2 and combustion will be stopped, resulting in high safety.

As described above, the liquid fuel detection device of the present invention has the following effects.

(1) Since the configuration detects the amount of fuel consumed by changes in the liquid level, the average flow rate can be detected even if the flow is pulsating, and the detected value is the absolute value of the amount of fuel consumed, so it is not reliable. Highly accurate fuel flow rate detection is possible.

(2) Since all detection is performed in a non-contact manner without exposing sensors etc. to the fuel, even highly flammable fuel can be detected safely.

(3) It is a fuel-safe system, and the controller 25 can determine all abnormalities such as malfunctions of valve devices, liquid level sensors, fuel pumps, etc., and damage to detection tanks.

[Brief explanation of drawings]

FIG. 1 is a control block diagram of a liquid fuel detection device according to a first embodiment of the present invention, FIG. 2 is a sectional view explaining the operation of a liquid level sensor, and FIG. 3 is a control block diagram of a liquid fuel detection device according to a second embodiment of the present invention. FIG. 4 is a flow diagram illustrating the operation of the controller 11, and FIG. 5 is a sectional view showing the configuration of a conventional fluid flow rate sensor. 8...Fuel tank, 9...Fuel passage,
10...Detection tank, 11...Fuel pump, 15...Valve device, 18...
Liquid level sensor, 25... Controller, 27...
... Valve control section, 28... Fuel calculation section,
29...Fuel correction unit, 32...Remaining fuel determination unit, 33...Motor control unit (air supply amount control unit). Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2) Envoy sensor Figure 3 Figure 4

Claims (3)

[Claims] (1) A detection tank with a fixed volume that introduces liquid fuel in the fuel tank, a valve device that opens and closes a fuel passage that communicates the detection tank and the fuel tank, and supplies fuel to the combustor downstream of the valve device. It has a fuel pump, the detection tank is provided with a liquid level sensor that detects a change in the internal fuel liquid level, a valve control section that controls the valve device, and a valve control section that controls the valve device when the valve device closes the fuel passage. Liquid fuel detection consisting of a controller that includes a fuel calculation section that calculates the fuel consumption of the combustor based on the output of the liquid level sensor, and a fuel correction section that controls the drive amount of the fuel pump according to the output of the fuel calculation section. Device. (2) The liquid fuel detection device according to claim 1, wherein the controller includes an air supply amount control section that controls the supply amount of combustion air to the combustor according to the output of the fuel calculation section. (3) The controller has a remaining fuel determination unit that determines the amount of remaining fuel in the fuel tank based on the output of the liquid level sensor when the valve control unit is outputting an output to open the fuel passage by the valve device. The liquid fuel detection device according to scope 1.