JP3491737B2 - Oil burner with fuel flow detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil combustor which enables stable combustion by monitoring the fuel flow rate.

[0002]

2. Description of the Related Art A fuel pump is attached to a fuel pipe connecting an oil tank and a burner to feed fuel from the oil tank to the burner, while a blower is provided to feed combustion air to the burner. And the amount of air blown by a blower are controlled to change the amount of fuel and air in a well-balanced manner to change the amount of heat generated by the burner. In an oil combustor, combustion is performed by providing a stepless or multi-stage combustion point. At this combustion point, the air amount for the oil feed amount or the oil feed amount for the air amount is set in advance so that the burner will completely burn. These are controlled by a microcomputer.

However, a filter, a fuel nozzle, etc. are attached to the fuel flow path from the oil tank to the burner, and if the filter is clogged with dust or tar is attached to the fuel nozzle of the burner, a great resistance to the flow of fuel will occur. It will be. Then, when the flow path resistance increases in this way,
Even if the fuel pump performs a predetermined flow rate operation, the burner is not sent at a predetermined flow rate and the balance with the blown air amount is lost,
May cause incomplete combustion.

As a countermeasure for this, an orifice is provided in the fuel pipe, the flow rate through the orifice is known from the pressure difference on both sides of the orifice, and fine adjustment of the operation of the fuel pump or blower is performed based on this data to achieve incomplete combustion. Can be prevented. In addition, a thermistor flow meter (velocimeter) is generally known as a device for measuring the flow velocity of a fluid such as air. When a constant current is applied to the thermistor, the thermistor generates heat, and the resistance value at this time depends on the characteristics of the thermistor. Can be calculated, but the amount of heat of the heating element radiates heat to this fluid when there is a flow in the fluid, so there is a difference between the calculated resistance value and the measured resistance value, and from this difference the flow velocity (flow rate) of the fluid
You can know.

[0005]

The method of providing an orifice in a fuel pipe is effective for an oil combustor having a large calorific value and can be put into practical use in combination with a recent small pressure sensor. The calorific value is small,
That is, when the flow velocity flowing through the fuel pipe is slow, the error becomes large and it is difficult to use. If the diameter of the orifice is reduced to obtain accuracy, the problem of orifice clogging and the pressure difference due to the orifice may affect the discharge flow rate of the fuel pump, so it cannot be used for a versatile control device. It was

A conventional thermistor type flow sensor has a large shape and is difficult to mount on a fuel pipe having an inner diameter of about 3 mm. If a portion having a large inner diameter of the fuel pipe is locally formed, a thermistor type flow rate sensor is used. Even if the sensor could be attached, the flow velocity was slow and there was a problem in terms of measurement accuracy, making it difficult to implement this method.

[0007]

SUMMARY OF THE INVENTION The present invention is to solve the above problems, and a fuel pump 4 is attached to a fuel pipe 3 connecting an oil tank 1 and a burner 2 to form a fuel flow in the fuel pipe 3. The temperature detecting element 5 combined with the heating element 5a is attached to the fuel pipe 3, and the flow velocity flowing in the fuel pipe 3 is detected from the amount of energy supplied to the heating element 5a and the measured temperature of the temperature detecting element 5, and In the oil combustor for controlling the discharge flow rate of the fuel pump 4 or the amount of air supplied to the burner 2 based on the above, a part of the heating element 5a for detecting the fuel flow rate and the temperature detecting element 5 is the fuel pipe 3
A fuel pipe 3 which is formed on a thin plate substrate 5b having good conductivity and which is disposed inside thereof and which is separated from the temperature detecting element 5 by a predetermined distance.
A thin plate-shaped oil temperature sensor 6 is inserted therein, and an attachment portion of the oil temperature sensor 6 of the fuel pipe 3 and the temperature detection element 5 is provided in the vertical portion 3a of the fuel pipe 3, and the oil temperature sensor 6 and the temperature detection element The thin plates forming the element 5 are arranged along the fuel flow, and the fuel is set so as to flow from the bottom to the top of the vertical portion 3a of the fuel pipe 3.

A filter frame 8 having a filter 7 installed in the fuel pipe 3 connecting the oil tank 1 and the burner 2
And the discharge fuel flow passage 8a of the filter frame 8 is formed integrally with the filter frame 8, and the discharge fuel flow passage 8a is arranged upward at the normal mounting position of the filter frame 8 and Since the oil temperature sensor 6 and the temperature detecting element 5 are attached to the flow path 8a and the detecting portion of the fuel flow rate detector is handled integrally with the filter frame body 8, a fuel is newly added to realize the specified attachment structure. It became unnecessary to make a detection part in the middle of the pipe 3.

[0009]

In the present invention, the shape of the temperature detecting element 5 is devised and a structure is proposed in which the flow velocity can be measured without error even with the fuel pipe 3 having a small inner diameter. The temperature detecting element 5 and the heating element 5a have good heat conductivity. It is constructed on the thin plate substrate 5b, and a part of this substrate 5b is mounted in the fuel pipe 3 without countering the flow of fuel, and as a result of being heated by the heat quantity of the heating element 5a, part of the fuel Even if the gas is gasified, by arranging the temperature detecting element 5 in the vertical portion of the fuel pipe 3, the bubbles quickly flow upward, and even if the fuel pipe 3 is thin, there is no passage error or measurement error due to the adhered gas. The flow rate data enables the oil combustor to fine-tune combustion and maintain stable combustion.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings showing an embodiment. 1 is an oil tank for storing fuel to be supplied to an oil combustor,
Reference numeral 2 is a burner housed in the frame of the oil combustor, and 3 is a fuel pipe connecting the oil tank 1 and the burner 2. 4 is a fuel pump installed in the middle of the fuel pipe 3, 9 is a burner 2
The blower 10 for supplying combustion air to the burner controller 10 is a burner controller incorporating a microcomputer.
In response to the signal a, the fuel pump 4, the blower 9, the spark ignition device 11 and the like are controlled so that the burner 2 can perform stable combustion.

The petroleum combustor of the embodiment is a pressure spray pot type petroleum combustor, 12 is a pot constituting a burner 2 having a large number of air holes in its side wall, and 13 is a fuel atomized in the pot 12. The flow rate of fuel sent from the spray nozzle 13 to the pot 12 is changed by controlling the fuel pump 4, and the combustion air amount is changed by changing the rotation speed of the blower 9. It has a function of changing the air and the fuel in a well-balanced manner to normally burn the burner 2.

When the burner controller 10 controls the fuel pump 4 composed of an electromagnetic pump, the flow rate of fuel supplied to the burner 2 can be changed by changing the drive frequency or the drive pulse. However, in this case the fuel pump 3
In order to send an accurate fuel flow rate, it is preferable to detect the actual fuel flow rate and control the fuel pump 4 and the blower 10 based on this data in order to send an accurate fuel flow rate.

Reference numeral 5 is a temperature detecting element arranged in the fuel flow path in combination with the heating element 5a. Although the heating element 5a rises in temperature when a constant current is passed, it is cooled by a fluid flowing in the vicinity and is higher than the expected temperature. If the actual temperature is measured by the temperature detecting element 5, the flow velocity can be known from the specific heat of the fluid passing through the fuel pipe 3, and the flow rate can be calculated from the diameter of the combustion pipe 3. Usually, a thermistor having the function of the heating element 5a is used as the temperature detecting element 5, and a constant current is passed through the thermistor to generate heat, and the temperature of the heated thermistor can be known from the resistance value. The flow velocity can be detected.

As another general method for measuring the fuel flow rate, an orifice is formed in the fuel pipe 3, and the flow rate passing through the orifice can be known from the pressure difference before and after the orifice.

However, the structure using the conventional thermistor is also
The structure that uses an orifice also makes the measuring device large,
It is difficult to apply to small-sized petroleum combustors for household use, etc., and in such medium-sized or smaller petroleum combustors, it is not common to measure the fuel flow rate and control based on this. Absent. This invention realizes downsizing of the measuring device,
It proposes a mounting method that is less prone to errors.

Reference numeral 5b denotes a thin plate substrate having a good heat transfer property, for example, a copper plate, which is inserted into the fuel pipe 3 at one end, 14 is a base member laminated on one side of the thin plate substrate 5b, and 14a is an end of the thin plate substrate 5b. Is a wiring connection portion formed at the end of the base member 14 protruding from the portion, and the heating element 5a is formed by coating on the base member 14, and from both ends of the heating element 5a to the wiring connection portion 14a of the base member 14. A conductive portion is formed.

Reference numeral 15 is an insulating layer that covers the heating element 5a and the conductive part in the middle, and 16 is a heat-sensitive resistance film formed by coating on the insulation layer 15. From both ends of the heat-sensitive resistance film 16, the base member 14 is formed.
A conductive portion is formed up to the wiring connection portion 14a. Reference numeral 17 is a base member 1 other than the wiring connection portion 14a connected to the conductive portion.
4 is a cover layer formed of an insulating coating so as to cover the entire surface of No. 4, and the sensor portion of the temperature detecting element 5 is formed by stacking a plurality of layers on a thin plate substrate 5b having good heat conductivity.

Reference numeral 18 is a terminal plate connected to external wiring,
The wiring connection portion 14a of the base member 14 and the terminal plate 18 are connected by a conductive wire 18a, and the sensor portion other than the tip end portion of the thin film substrate 5b and the root of the terminal plate 18 are integrally sealed with a resin mold to form a heating element. The temperature detecting element 5 is integrated with 5a.

Reference numeral 3a is a vertical portion formed in the middle of the fuel pipe 3 so that fuel flows from bottom to top. The exposed end of the thin plate substrate 5b of the temperature detecting element 5 is located at this vertical portion. It is arranged in the fuel pipe 3 of 3a,
Like the fuel flow indicated by the broken line in the perspective view of the temperature detecting element 5 of FIG. 3, the end of the thin plate 6b is arranged along the fuel flow so as not to obstruct the fuel flow in the fuel pipe 3. There is.

Reference numeral 6 denotes an oil temperature sensor having a structure similar to that of the temperature detecting element 5 and having a heat-sensitive resistance film incorporated therein. The oil temperature sensor 6 is the same vertical portion 3a of the fuel pipe 3 as the temperature detecting element 5. The oil temperature sensor 6 is mounted below the temperature detecting element 5, which is the upstream side of the fuel flow, as shown in the drawing. Since the temperature detecting element 5 is equipped with the heating element 5a and the heat-sensitive resistance film 16, it functions as a temperature sensor when the heating element 5a is not energized. Therefore, in the embodiment, a temperature sensor having a similar structure is newly developed. Instead, the same element as the temperature detection element 5 is used as the oil temperature sensor 6.

Since the heat energy to be radiated by the heating element 5a of the temperature detecting element 5 is determined by passing a constant current, the temperature rise when there is no heat radiation to the fuel is higher than the temperature detected by the oil temperature sensor 6. Can be expected. On the other hand, when the amount of heat of the heating element 5a radiates heat to the flow of fuel, the temperature detection element 5 detects a temperature lower than the expected temperature, and data such as the specific heat of the fuel, the inner diameter of the fuel pipe, the amount of heat radiated to the fuel, etc. From this, the flow velocity and the flow rate of the fuel can be calculated.

Reference numeral 19 denotes a flow rate calculating section in which the temperature detecting element 5 and the oil temperature sensor 6 are assembled. The flow rate calculating section 16 can be incorporated in the burner controller 10 as in the embodiment. If the flow rate calculator 16 is made independent,
The fuel flow rate detection unit can be supplied as a common component to similar oil combustors, which improves versatility.

The present invention makes it possible to finely control the burner 2 by detecting the flow rate of the fuel passing through the fuel pipe 3 even in a small petroleum combustor used in an ordinary home or a small business establishment, and various disturbances can be performed. Even if the flow rate varies depending on the conditions, complete combustion can always be maintained. Specifically, this type of oil combustor has a low calorific value, and the fuel pipe 3
The inner diameter of the thin pipe is about 3 mm, and in order to attach a flow rate sensor to the fuel pipe 3, a sensor portion is formed at the end of the thin plate substrate 5b having good heat transfer property.
Only one side of is positioned inside the fuel pipe 3.

The attachment of the thin plate 5b is arranged so as not to oppose it along the flow of fuel so that it does not become a resistance to the flow in the thin fuel pipe 3. Further, since the temperature detecting element 5 is attached to the vertical portion 3a of the fuel pipe 3 in which the fuel flows from the bottom to the top, the temperature of the thin plate substrate 5b is increased by the heating element 5a, and the temperature of the fuel touching the thin plate substrate 5b is increased. Even if the unit receives this temperature and generates bubbles, the bubbles can be quickly separated from the thin plate 5b by the floating force of the bubbles and the flow of fuel.

That is, in a petroleum combustor with a small amount of heat generation, since the flow velocity of the fuel passing through the fuel pipe 3 is slow, if the bubbles of the fuel are generated, the state of being adhered to the thin plate substrate 5b is maintained. It has been found that at this time, the fuel flows so as to avoid the thin plate substrate 5b, the heat dissipation state changes greatly, and the value of the measured flow rate becomes unreliable. If the oil combustor continues to operate in this state, the burner controller 10 will operate in a direction that upsets the balance of fuel and air, causing serious trouble.

By identifying the mechanism of the occurrence of this trouble, the mounting method of the temperature detecting element 5 of this kind can be specified, and there is a fuel flow from the bottom to the top, and this fuel is the thin plate 5b. Since it is flowing along the surface of the thin plate substrate 5b, even if bubbles are generated in this portion, it will not be retained as it is attached to the surface of the thin plate substrate 5b, and the bubbles will quickly separate and flow upward. A combustor is one that does not cause abnormal combustion.

By the way, as an implementation structure of the vertical portion 3a of the fuel pipe 3 to which the temperature detecting element 5 is attached, the present invention proposes a combination with a filter structure which is often used in an oil combustor of this type. That is, 8 is a filter frame body attached in the middle of the fuel pipe 3 that connects the oil tank 1 and the burner 2, and 8b is a filter that is detachably attached to the main body of the filter frame body 8 to form an oil storage space inside. A cup, 7 is a filter mounted in the oil storage space of the filter cup 8b, and 8a is a discharge fuel flow path for taking out the fuel passing through the filter 7 from the filter frame 7.

The discharge fuel flow passage 8a is formed upward so as to be vertical when the filter frame 8 is attached to a normal position, and the discharge fuel flow passage 8a constitutes a part of the fuel pipe 3. . In the present invention, the vertical portion 3a of the fuel pipe 3 is caused to function in the discharged fuel flow passage 8a, the temperature detecting element 5 and the oil temperature sensor 6 are attached to this portion, and the flow rate calculating portion 19 and the filter frame 8 are also attached. It is configured integrally with.

With this structure, it is not necessary to specially make the vertical portion 3a of the fuel pipe 3 to which the parts for measuring the flow rate are attached, and the upward discharge fuel port of the filter frame 8 is extended to discharge the discharge fuel. Since only the flow path 8a is used, the cost is slightly increased, and the parts can be managed only by managing the filter, which is not a burden and the handleability is improved.

[0030]

According to the present invention, the temperature detecting element 5 is formed on the thin plate substrate 5b having good electrothermal properties, and only the tip of the thin plate substrate 5b is inserted into the fuel pipe 3, and the thin plate of the temperature detecting element 5 is formed. The temperature detecting element 5 is arranged along the fuel flow, and the temperature detecting element 5 is attached to the vertical portion 3a in the middle of the fuel pipe 3 through which the fuel flows from bottom to top.

Even if the fuel contacting the surface of the thin substrate 5b whose temperature is raised by the heating element 5a of the temperature detecting element 5 becomes bubbles, the buoyancy of the bubbles and the fuel on the surface of the thin substrate 5 The air flow is such that the bubbles are separated from the thin plate 5b. For this reason, since the thin plate 5b to be inserted into the thin fuel pipe 3 is small, if bubbles adhere to the surface, the fuel flow cannot sufficiently contact the thin plate 5b, and abnormal flow rate data is output. As a result, the oil combustor may have caused abnormal combustion, but the temperature detection element 5 can reliably contact the fuel flowing through the fuel pipe 3 and always output normal flow rate data due to the above structure. It was

Further, in order to newly attach the temperature detecting element 5 to the fuel pipe 3, it is necessary to additionally attach the special fuel pipe 3 having the vertical portion 3a. Since the discharge fuel flow path 8a facing toward the above is provided and the temperature detecting element 5 is attached to this portion, the flow rate detector of the present invention can be handled integrally with the filter frame body 8, and special parts are managed as the flow rate detector. Without using it, parts management is used as a filter, so even though functions have been added, there is no special effort, and no particular burden is felt.

Further, since it is not necessary to add the fuel pipe 3 having the vertical portion 3a for the temperature detecting element 5,
The cost can be increased only slightly, and it is possible to provide an excellent petroleum combustor that always achieves normal combustion by balancing fuel and air at a very low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a filter portion showing an embodiment of the present invention.

2 is a cross-sectional view of a part used in the embodiment of FIG.

3 is a perspective view of parts used in the embodiment of FIG. 1. FIG.

FIG. 4 is a sectional view of an oil combustor showing an embodiment of the present invention.

[Explanation of symbols]

1 oil tank 2 burners 3 fuel pipe 3a Vertical part 4 fuel pump 5 Temperature detection element 5a heating element 5b Thin board 6 Oil temperature sensor 7 filters 8 filter frame 8a discharge fuel flow path

Claims (2)

(57) [Claims] 1. A temperature detection element in which a fuel pump 4 is attached to a fuel pipe 3 connecting an oil tank 1 and a burner 2 to form a fuel flow in the fuel pipe 3, and the fuel pipe 3 is combined with a heating element 5a. 5 is attached, the flow velocity flowing in the fuel pipe 3 is detected from the amount of energy supplied to the heating element 5a and the measured temperature of the temperature detection element 5, and the discharge flow amount of the fuel pump 4 or the burner 2 is supplied based on the detected flow velocity. In an oil combustor that controls the amount of air, a part of the heating element 5a that detects the fuel flow rate and the temperature detection element 5 are the fuel pipe 3
A fuel pipe 3 which is formed on a thin plate substrate 5b having good conductivity and which is disposed inside thereof and which is separated from the temperature detecting element 5 by a predetermined distance.
A thin plate-shaped oil temperature sensor 6 is inserted therein, and an attachment portion of the oil temperature sensor 6 of the fuel pipe 3 and the temperature detection element 5 is provided in the vertical portion 3a of the fuel pipe 3, and the oil temperature sensor 6 and the temperature detection element An oil combustor with a fuel flow rate detector, in which the thin plates constituting the element 5 are arranged along the fuel flow, and the fuel is set to flow from the bottom to the top of the vertical portion 3a of the fuel pipe 3. 2. A fuel pipe 3 connecting the oil tank 1 and the burner 2 is provided with a filter frame 8 having a filter 7 therein, and a discharge fuel flow path 8a of the filter frame 8 is integrated with the filter frame 8. The fuel flow rate detector is formed and the discharge fuel flow passage 8a is arranged upward at the normal mounting position of the filter frame 8 and the oil temperature sensor 6 and the temperature detecting element 5 are attached to the discharge fuel flow passage 8a. The petroleum combustor with a fuel flow rate detector according to claim 1, characterized in that the detection unit of (1) is handled integrally with the filter frame (8).