JPH08193715A - Fuel feeder of combustion device - Google Patents

Abstract

PURPOSE: To obtain a fuel feeder of a combustion device, which allows stable, constant combustion of kerosene by a spray nozzle without a fluctuation in the flow rate of kerosine even when a change in temperature occurs. CONSTITUTION: A fuel feeder is equipped with a fuel temperature sensor 17 to detect the temperature of liquid fuel and a flow rate compensating device 30 that corrects the flow path area of a flow control valve 7 in response to detected signals from the fuel temperature detecting sensor 17 to compensate the flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for a combustion device in which liquid fuel is sprayed from a spray nozzle and burned.

[0002]

2. Description of the Related Art A fuel supply device for a combustion device of this type constantly supplies a fixed amount of oil, which is introduced from an oil tank to an oil feed pipe, to a spray nozzle by means of a fuel pump, and supplies the oil feed pipe upstream of the fuel pump. The combustion amount is adjusted by changing the amount of oil returned from the spray nozzle via the oil return pipe.

In order to accurately control the amount of combustion,
A return pipe valve for changing the flow passage area of the oil return pipe, and a throttle portion for narrowing the flow passage area of the oil feed pipe upstream of the joining portion (the joining portion of the oil feed pipe and the oil return pipe) are provided. Improvements have been made so that the operation of the return line valve is controlled by the pressure difference between the oil feed pipes on the upstream side and the downstream side of the throttle portion (JP-A-5-60).
320).

According to such an improved structure, the flow rate of petroleum used for combustion in the spray nozzle is determined from the flow passage area of the throttle of the oil feed pipe and the differential pressure across the flow passage. Since the return flow rate only changes accordingly, the flow rate of petroleum used for combustion can be directly controlled only by adjusting the flow passage area of the throttle portion.

[0005]

However, in reality, the flow rate Q of petroleum is further influenced by the kinematic viscosity coefficient μ of petroleum,
The flow rate Q is proportional to (1 / μ) ^0.8 . In the case of petroleum, the coefficient of kinematic viscosity μ changes greatly with temperature.

Therefore, in the conventional device for adjusting only the flow passage area of the throttle portion provided in the middle of the oil feed pipe, the flow rate of petroleum used for combustion in the spray nozzle fluctuates under the influence of temperature change. I had a problem.

Therefore, according to the present invention, the flow rate of petroleum used for combustion in the spray nozzle does not change even if the temperature changes,
An object of the present invention is to provide a fuel supply device of a combustion device capable of performing constant and stable combustion.

[0008]

In order to achieve the above object, a fuel supply device for a combustion device according to the present invention is a fuel supply device for a combustion device in which liquid fuel is sprayed from a spray nozzle and burned. And a fuel temperature detection sensor for detecting the temperature of the liquid fuel, in which a flow rate adjusting valve for adjusting the flow rate of the liquid fuel is provided in the middle of the feed pipe for sending the liquid fuel to the spray nozzle, Flow rate compensating means for compensating the flow rate by correcting the flow passage area of the flow rate adjusting valve in response to the detection signal output from the fuel temperature detecting sensor is provided.

Further, the fuel supply device for the combustion apparatus of the present invention comprises a fuel pump inserted in the middle of the feed pipe so as to always feed a fixed amount of liquid fuel from the feed pipe to the spray nozzle, and the fuel pump A return pipe for returning a part of the liquid fuel from the spray nozzle to a merging portion that merges with the feed pipe on the upstream side, a return conduit valve for changing the flow passage area of the return pipe, and the merging portion. A throttle portion that narrows the flow passage area of the feed pipe on the upstream side, and a differential pressure operation that operates by the differential pressure in the feed pipe upstream and downstream of the throttle portion to control the operation of the return conduit valve. And a spring for balancing the differential pressure between the upstream side and the downstream side of the throttle portion in the differential pressure operating means in the differential pressure operating means with a bimetal whose spring load changes with temperature. Te placed above the liquid fuel, the spring load of the spring, characterized in that so as to vary in response to temperature changes of the liquid fuel.

Further, a low temperature acting spring may be added to the spring, which acts only when the spring load balanced with the pressure difference in the feed pipe is low temperature.

[0011]

When the fuel temperature detecting sensor is provided, the flow passage area of the flow rate adjusting valve is corrected according to the temperature of the liquid fuel detected by the fuel temperature detecting sensor. As a result, even if the kinematic viscosity coefficient of the liquid fuel changes depending on the temperature, the flow rate of the liquid fuel is compensated and the flow rate of petroleum used for combustion in the spray nozzle does not change.

In the differential pressure operating means, in which the spring for balancing the differential pressure between the upstream and downstream sides of the throttle portion is made of bimetal and arranged in the liquid fuel, the spring load is equal to the temperature of the liquid fuel. Change in response to changes. As a result, even if the kinematic viscosity of liquid fuel changes with temperature,
The flow rate of the liquid fuel is compensated so that the flow rate of the petroleum used for combustion in the spray nozzle does not fluctuate.

In addition to the spring, a spring at low temperature, in which the spring load balanced with the differential pressure acts only at low temperature, is added, and the flow rate of the liquid fuel is more accurately compensated at low temperature where the kinematic viscosity of the liquid fuel increases. Thus, the flow rate of petroleum used for combustion in the spray nozzle does not change.

[0014]

Embodiments will be described with reference to the drawings. Figure 1
1 shows the first embodiment of the present invention, in which oil in the oil tank 1 is fed by a fuel pump 3 inserted in the middle of an oil feed pipe 2 that connects the oil tank 1 and the spray nozzle 4 to each other. A constant amount is always sent to the spray nozzle 4 through the pipe 2.

A part of the petroleum oil sprayed in the tip of the spray nozzle 4 passes through the oil return pipe 5, and upstream of the fuel pump 3, the oil feed pipe 2 joins the oil feed pipe 2. Returned to 2.

Therefore, from the spray nozzle 4 to the oil return pipe 5
By changing the amount of petroleum returned through the spray nozzle 4, the amount of petroleum sprayed from the spray nozzle 4 to the combustion section and provided for combustion is controlled.

A needle-shaped feed line valve 7 for changing the flow passage area of the oil feed pipe 2 is axially moved forward and backward by an electromagnetic solenoid 20 in the oil feed pipe 2 upstream of the confluence portion 6. Are arranged as follows. Reference numeral 21 is an electromagnetic coil of the electromagnetic solenoid 20, and 22 is a movable iron core to which the base end of the feed conduit valve 7 is connected.

The feed line valve 7 is formed such that the tip end side is tapered and is inserted into a hole 8 which is a part of the oil feed pipe 2. Therefore, the gap between the feed conduit valve 7 and the hole 8 serves as a throttle portion 9 that narrows the oil feed pipe 2 in the middle.

Pressure difference before and after the throttle portion 9 (differential pressure ΔP)
Is constant, the flow rate of the oil flowing therethrough is proportional to the flow passage area of the narrowed portion 9 (strictly speaking, the effective flow passage area) under the condition where the temperature is constant.

Therefore, by changing the value of the current flowing through the electromagnetic coil 21 of the electromagnetic solenoid 20 and moving the feed line valve 7 in the direction of inserting it deeply into the hole 8, the flow passage area of the oil feed pipe 2 becomes narrow. The oil flow rate has decreased and the feed line valve 7
If the oil is moved in the direction of pulling out from the hole 8, the flow passage area of the oil feed pipe 2 becomes wider and the oil flow rate increases. Reference numeral 10 is a stop valve for completely closing the hole 8 when the oil feed pipe 2 is fully closed.

In the middle of the oil return pipe 5, a ball-shaped return pipe valve 12 for changing the flow passage area of the oil return pipe 5 is arranged biased by a compression coil spring 13 toward the valve seat 11. Has been done.

As shown in FIG. 1, its return line valve 1
A wide space is formed between the two parts and the feed line valve 7 part, and the space is partitioned by a diaphragm 15 formed in a disk shape.

Therefore, the oil pressure in the oil feed pipe 2 upstream of the throttle portion 9 is applied to the surface of the diaphragm 15 on the feed line valve 7 side, and the surface of the diaphragm 15 on the return line valve 12 side is Petroleum pressure in the oil feed pipe 2 on the downstream side of the throttle unit 9 is applied via the confluence unit 6.

As a result, the diaphragm 15 has a diaphragm portion 9
A differential pressure ΔP of oil pressure in the upstream and downstream oil feed pipes 2 is applied, and the differential pressure ΔP is vertically attached to the central portion of the diaphragm 15 so that the top portion contacts the return line valve 12. Compression coil spring 1 through the rod 16
The return line valve 12 is pushed and opened against the biasing force of No. 3.

The return line valve 12 is connected to the diaphragm 1
The flow area of the oil return pipe 5 is increased or decreased so that the differential pressure ΔP applied from 5 and the urging force of the compression coil spring 13 are balanced, and the flow rate of the oil returned from the spray nozzle 4 to the merging portion 6 is controlled. Thereby, the differential pressure ΔP applied to the diaphragm 15 (that is, the differential pressure across the diaphragm 9) is always maintained constant.

In the apparatus constructed as described above, the flow rate of the petroleum flowing through the throttle portion 9 of the feed pipe valve 7 is the petroleum consumed by the spray nozzle 4, that is, the petroleum used for combustion in the combustion portion. Is the flow rate itself.

Since the flow rate of the oil is determined only by the flow passage area of the throttle portion 9 if there is no temperature change, the feed line valve 7 is moved back and forth by the electromagnetic solenoid 20 to move the throttle valve 9 in the throttle portion 9. By controlling the flow passage area, the flow rate of petroleum used for combustion is controlled, and following it,
The flow rate of the oil returned to the confluence section 6 via the oil return pipe 5 changes.

A thermistor 17 whose electric resistance value increases as the temperature decreases is attached in the flow path of the merging portion 6. Both ends of the thermistor 17 are connected to a coil drive control circuit 30 for controlling the drive current value supplied to the electromagnetic coil 21.

FIG. 2 shows an example of the coil drive control circuit 30, which is a constant current circuit for supplying a constant drive current to the compensating circuit 31 including the thermistor 17 and the electromagnetic coil 21 of the electromagnetic solenoid 20. It is composed of 32. Reference numeral 33 is a diode for short-circuiting an induced current generated when the drive current is turned off.

The compensation circuit 31 includes an operational amplifier 311 and a plurality of resistors connected to it, and one of two resistors (resistance values R2 and R3) connected in series in the feedback line of the operational amplifier 311. (Resistance value R2)
The thermistor 17 is connected in parallel with.

As a result, as the resistance value Rt of the thermistor 17 increases, the input voltage Vin is greatly amplified in the compensating circuit 31, and the output voltage Vout thereof is constant current circuit 32.
Is output to.

In the case of the compensation circuit 31, assuming that the resistance values of the resistors are R1, R2 and R3 and the resistance value of the thermistor 17 is Rt as shown in FIG. 2, the relationship between the input voltage Vin and the output voltage Vout is shown. Is as follows.

[0033]

[Equation 1]

The constant voltage supplied from the compensation circuit 31 to the constant current circuit 32 is the operational amplifier 3 which constitutes the constant current circuit 32.
21, transistor 322 and two resistors 323, 32
It is converted into a constant current by 4 and supplied to the electromagnetic coil 21 of the electromagnetic solenoid 20.

As a result, when the temperature of the oil flowing in the vicinity of the merging portion 6 changes, the resistance value of the thermistor 17 for detecting it changes, and the oil is supplied to the electromagnetic coil 21 of the electromagnetic solenoid 20 correspondingly. The drive current value changes, the position of the feed conduit valve 7 changes, and the flow passage area of the throttle unit 9 is corrected.

Therefore, even if the kinematic viscosity μ of the oil changes due to the temperature change, the flow rate of the oil passing through the throttle portion 9 does not change, and the flow rate of the oil used for combustion in the spray nozzle 4 is always constant. can do.

FIG. 3 shows an experimental result showing how much the driving current value of the electromagnetic coil 21 should be changed. For example, in order to maintain the flow rate of 48 milliliters per minute, at a point of 25 ° C. A drive current of 170 milliamps is required, whereas a 0 ° C. point requires 185 milliamps and a -20 ° C. point requires 205 milliamps.

Therefore, the drive current value of the electromagnetic coil 21 is
By changing the resistance value of the thermistor 17 as shown in FIG. 4 when the temperature at 25 ° C. is 1, the flow rate change due to temperature can be made extremely small over a wide range.

FIG. 5 shows a second embodiment of the present invention. While the first embodiment electrically corrects the flow rate, the same correction is mechanically performed. It was done like this.

Here, in order to balance with the differential pressure ΔP of the oil in the oil feed pipe 2 on the upstream side and the downstream side of the throttle portion 9, the diaphragm 15 is provided from the return line valve 12 side to the feed line valve 7 side. A disc spring 40 for urging is provided in addition to the compression coil spring 13.

The disc spring 40 is always provided in a compressed state, and acts so that the spring load is added to the spring load of the compression coil spring 13. The thermistor 17 is not provided. The other structure is the same as that of the first embodiment.

The disc spring 40 is made of bimetal which is deformed by temperature, and the convex side is, for example, Z.
It is formed of a high expansion material of n-Cu, and the concave side is made of, for example, Ni-
It is made of a low expansion material of Fe.

Therefore, when the temperature decreases, the angle of the dish rises and the spring load increases as shown in FIG.
When the spring load increases, the differential pressure ΔP across the throttle 9 increases, so that the flow rate of oil flowing through the throttle 9 increases.

The disc spring 40 is arranged in the oil in the oil return pipe 5 immediately before the confluence portion 6. Therefore, when the oil temperature decreases, the spring load of the disc spring 40 correspondingly increases, and the kinematic viscosity coefficient μ of oil increases and decreases. Compensated by the increase.

FIG. 7 shows the result, and in the case where the disc spring 40 made of bimetal is provided, the solid line shows the flow rate characteristic in the state where the disc spring 40 shown by the broken line is not provided. As described above, the flow rate characteristics are less affected by temperature.

However, even in this case, in the low temperature region lower than 0 ° C., the tendency of the flow rate decrease due to the increase of the kinematic viscosity coefficient μ appears to some extent. Therefore, in the third embodiment, the disc spring 4
As 0, a bimetal disc spring 40 having two spring portions 401 and 402 having different inclination angles is used as shown in FIG. The overall structure is the same as that of the second embodiment shown in FIG.

In this embodiment, the bimetal disc spring 4 is used.
6 spring parts of 0 are high spring parts 40 that are tall every other sheet.
1 and a low spring portion 402 which is short, and a high spring portion 4
01 is always compressed as in the second embodiment, but the low spring portion 402 is short because it is short, and is not compressed above 0 ° C., and when it is below 0 ° C., it is tall. Deform.

Therefore, the characteristic of the spring load that balances the differential pressure ΔP across the throttle portion 9 sharply rises in a temperature range lower than 0 ° C. as shown in FIG. 9, and as a result, the flow rate characteristic is as shown in FIG. It is corrected so that there is almost no fluctuation even in the low temperature region.

[0049]

According to the present invention, the flow passage area of the flow rate adjusting valve is corrected in accordance with the temperature of the liquid fuel detected by the fuel temperature detecting sensor, or the spring that balances with the differential pressure across the throttle portion is used. The spring load changes according to the temperature change of the liquid fuel to correct the differential pressure across the throttle, and as a result, the flow rate of the liquid fuel is compensated even if the kinematic viscosity of the liquid fuel changes with temperature. The flow rate of petroleum used for combustion in the spray nozzle does not fluctuate, and a stable combustion state can always be maintained.

Further, in the case where a spring at low temperature which acts only when the spring load for balancing with the differential pressure acts at low temperature is added to the spring, the flow rate of the liquid fuel is further increased in the low temperature region where the kinematic viscosity of the liquid fuel increases. Can be compensated accurately.

[Brief description of drawings]

FIG. 1 is a side sectional view of a first embodiment.

FIG. 2 is a block diagram of a coil drive control circuit according to the first embodiment.

FIG. 3 is a flow rate characteristic diagram for each drive current value according to the first embodiment.

FIG. 4 is a drive current ratio characteristic diagram of the first embodiment.

FIG. 5 is a side sectional view of the second embodiment.

FIG. 6 is a spring load characteristic diagram of the second embodiment.

FIG. 7 is a flow rate characteristic diagram of the second embodiment.

FIG. 8 is a perspective view of a disc spring of a third embodiment.

FIG. 9 is a spring load characteristic diagram of the third embodiment.

FIG. 10 is a flow rate characteristic diagram of the third embodiment.

[Explanation of symbols]

 2 Oil feed pipe 3 Fuel pump 4 Spray nozzle 5 Oil return pipe 6 Confluence part 7 Feed pipe line valve 9 Throttling part 12 Return pipe line valve 15 Diaphragm 17 Thermistor 40 Disc spring

Claims (3)

[Claims] 1. A fuel supply device for a combustion device, wherein liquid fuel is sprayed from a spray nozzle and burned, for adjusting the flow rate of the liquid fuel in the middle of a feed pipe for sending the liquid fuel to the spray nozzle. In which the flow rate adjusting valve is provided, the fuel temperature detecting sensor for detecting the temperature of the liquid fuel, and the flow passage area of the flow rate adjusting valve in response to the detection signal output from the fuel temperature detecting sensor. A fuel supply device for a combustion apparatus, comprising: a flow rate compensating means for correcting and compensating the flow rate. 2. A fuel pump inserted in the middle of the feed pipe so as to constantly feed a fixed amount of liquid fuel from the feed pipe to a spray nozzle, and a merging portion that joins the feed pipe upstream of the fuel pump. Up to a return pipe for returning a part of the liquid fuel from the spray nozzle, a return pipe valve for changing the flow passage area of the return pipe, and a flow passage area of the feed pipe on the upstream side of the joining portion. In a fuel supply device for a combustion device, a throttle part for narrowing the throttle valve, and a differential pressure operating means for controlling the operation of the return conduit valve by operating by the differential pressure in the feed pipe on the upstream side and the downstream side of the throttle part. In the differential pressure operating means, a spring for balancing the differential pressure between the upstream side and the downstream side of the throttle portion of the throttle portion is formed of bimetal whose spring load changes depending on temperature, and is arranged in the liquid fuel. Spring bar A fuel supply device for a combustion device, wherein a net load is changed in accordance with a temperature change of the liquid fuel. 3. The fuel supply system for a combustion apparatus according to claim 2, wherein a low temperature acting spring is added to the spring, the spring acting in equilibrium with the differential pressure in the feed pipe acts only at a low temperature.