JPS63259319A - Air-fuel ratio controller of burner - Google Patents

Abstract

PURPOSE:To simplify the structure of the air-fuel controller by allowing a fuel injection nozzle to contain therein a valve body moving in accordance with the quantity of a fuel injected thereby to control the quantity of air to be supplied in linkage with the movement of the valve body in the air-fuel ratio controller of the burner for use in a grain drying machine. CONSTITUTION:When the temperature of hot air is supplied from a hot air flow temperature sensor 118 to an electronic control circuit 92, the electronic control circuit 92 compares the temperature of the hot air flow with a preset temperature in accordance with a predetermined procedure and judges whether or not the quantity of the fuel to be injected is varied. In accordance with the result of the judgement, the quantity of power to a heater 90 is changed and the curvature degree of a bimetal 88 is changed. As a result, a rod member 44 moves to allow a valve body 36 to slide within a distributor 26 to open or close an injection port 18 and to adjust the quantity of the fuel. Then, the quantity of air to realize a predetermined air-fuel ratio is operated, and is converted into the rotational speed of a fan motor 124 to control the rotational speed of the fan through a drive circuit 122. Thus, the structure of the controller can be simplified.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an air-fuel ratio control device for a combustor, and in particular to an air-fuel ratio control device for a combustor that controls the amount of mixed air based on the amount of fuel injected from a fuel injection port. This invention relates to a fuel ratio control device.

[Prior art] Conventionally, in a combustor (burner) used to dry grain with hot air in a grain dryer, for example, fuel is supplied from a fuel pump or the like through a foot pipe to a nozzle with a fixed injection opening area. The fuel is injected from the injection port. The injected fuel is mixed with air blown by the rotation of the fan, atomized, and ignited by one ignition rod and burned, thereby generating hot air. By the way, the temperature of the a-air of the burner to be burned is determined by detecting the temperature of the hot air generated by the burner using a temperature sensor, etc., and comparing the detected hot air temperature with a preset temperature to determine the temperature of the hot air that is supplied to the burner. This is adjusted by controlling the amount of fuel supplied.

Further, in this case, the air fuel ratio of the burner is controlled to, for example, the stoichiometric air fuel ratio by controlling the amount of air supplied by a fan or the like based on the fuel supply amount.

[Problems to be solved by the invention] However, since the amount of fuel supplied to the burner is controlled by the supply pressure of a supply pump, etc., the atomization state of the fuel injected from the nozzle during small combustion is not good. As a result, it was not possible to mix well with air, resulting in incomplete combustion.

To solve this problem, the fuel may be atomized in advance and then injected from the nozzle (premix), but this requires a large number of parts and requires complicated control. In addition, in such a structure, it is necessary to install a safety device in the middle of the piping to prevent backfire.

In consideration of the above facts, the present invention makes it possible to control the fuel injection amount at the fuel injection port without changing the fuel supply pressure, and to control the air amount according to the fuel injection amount to achieve a predetermined air-fuel ratio. The purpose is to obtain an air-fuel ratio control device for a combustor that can be used.

[Means for Solving the Problems] The air-fuel ratio control device for a combustor according to the present invention includes an air-fuel ratio control device for a combustor that mixes and burns fuel injected from a fuel injection port and air. , 49 bodies movable between a first position for fully opening the fuel injection port and a second position for fully closing the fuel injection port, and a position of the valve body corresponding to a predetermined fuel injection amount. a control means for controlling the air-fuel ratio to a predetermined value by controlling the supply amount of air mixed with the injected fuel according to the position of the valve body;
have.

[Operation] When the combustion state of the combustor (for example, hot air temperature) is different from the predetermined combustion state (hot air temperature), the valve body is moved to the first position by the moving means.
By moving and positioning from the position to the second position, the opening area of the fuel injection port can be changed and the fuel injection amount can be changed. This allows for a prescribed combustion pattern! (8M temperature). That is, when it is desired to increase the hot air temperature, the valve body is moved toward the first position, and when it is desired to decrease the hot air temperature, the valve body is moved toward the second position. Thereby, the amount of fuel injected from the fuel injection port is changed according to the amount of movement of the valve body without changing the supply pressure. Here, since the control means of the present invention also controls the amount of air mixed with this fuel in accordance with changes in this fuel injection amount, it is possible to maintain an almost constant air-fuel ratio regardless of the fuel injection amount. No problems such as incomplete combustion will occur.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to one drawing.

FIG. 1 shows a cross-sectional view of the case where the variable injection amount nozzle 1O according to this embodiment is applied to a gun type burner for each fuel injection amount. Further, FIG. 2 shows an enlarged sectional view of the main part of FIG. 1, and FIG. 3 shows a perspective view of the main part. Further, FIG. 4 shows an explanatory diagram of the main part operation.

As shown in FIG. 1, the nozzle base 12 is approximately cylindrical,
The tip of the inner hole 13 (on the left side of the first hole) widens widely, and the second
As shown in the figure, a female threaded portion 14 is formed, and a spring receiving portion 15 with a slightly larger inner diameter is formed at the rear end. Further, a male threaded portion 1 is provided on the outer periphery of the rear end of the nozzle base 12.
7 is formed. A nozzle 16 is attached to the tip of the nozzle base 12 (the end on the female threaded portion 14 side).

As shown in FIG. 2, the nozzle 16 has a substantially U-shaped cross section along its axis, and has an injection port 18 formed at its tip. A male threaded portion 20 is formed on the outer periphery of the nozzle 16 on the opening side (the side opposite to the injection port 18). This male threaded portion 20 engages with the female threaded portion 14 to connect the nozzle base 12 and the nozzle 1.
It is designed to be combined with 6. Furthermore, the male thread part 2
An 0 ring 22 is disposed at the base end of the 0 so as to be sandwiched between the nozzle base 12 and the nozzle 16.

A female threaded portion 24 is formed on the inner periphery of the nozzle 16 on the opening side. A distributor 26 is attached to the female threaded portion 24.

As shown in FIG. 3, the distributor 26 has a substantially cylindrical shape and has a male threaded portion 28 formed on its outer periphery. This male threaded portion 28 engages with the female threaded portion 24 so that the distributor 26 or the nozzle 16 is accommodated therein. A fuel passage portion 30 is formed in a part of the outer circumference of the distributor 26 in the axial direction of the distributor 26 so as to remove the thread groove. Furthermore, grooves 32 are formed radially at the tip of the distributor 26. As a result, the distributor 2 is placed inside the nozzle 16.
6 is stored, the supplied fuel or the fuel passage part 30
The liquid passes through the groove 32 and is injected from the injection port 18 of the nozzle 16.

A through hole 34 is bored on the axis of the distributor 26, and a valve body 36 is slidably inserted into the through hole 34. The valve body 36 is rod-shaped and has a tapered needle portion 38 at its tip. By sliding the valve body 36 within the through hole β4, the needle portion 38 substantially changes the opening area of the injection port 18 formed in the nozzle 16. These structures are the same as those of generally known needle valves.

A ring-shaped stopper 40 is attached to the rear end of the valve body 36, and the stopper 40 and the rear end surface 2 of the distributor 26 are connected to each other.
A compression coil spring 42 is arranged between the spring 9 and the spring 9. As a result, the valve body 36 always moves in the direction opposite to the injection port 18 (
(rightward in Figure 1).

A rod member 44 is slidably disposed in the inner hole 13 of the nozzle base 12 . The rod member 44 is rod-shaped and has a tip end (
The first left side) is a small diameter portion 46 formed to have a slightly smaller diameter than the inner hole 13, and is in contact with the rear end of the valve body 36. A ring-shaped recess 48 is formed in the center of the rod member 44, into which an O-ring 50 is fitted.

Furthermore, a threaded portion 52 is formed at the rear end of the rod member 44 protruding from the nozzle base 12.

A minimum injection amount adjusting nut 54 for positioning the valve body 36 at the second position is screwed together with a lock nut 56 near the base end of the threaded portion 52. Minimum injection amount 3J1'lli
The nut 54 and the lock nut 56 are tightened together and fixed to the threaded portion 52 as a double lock nut. The minimum injection amount regulating nut 54 is connected to the rod member 44 or the first
When the rod member 44 slides a set amount toward the left in the drawing, it comes into contact with the rear end surface of the nozzle base 12 to control the amount of sliding of the rod member 44.

The minimum injection amount adjusting nut 54 and the bottom PX of the spring receiving portion 15 formed on the nozzle base 12! A compression coil spring 58 is arranged between the spring 15A and the spring 15A. Therefore, the rod member 44 is always projected from the nozzle base 12 by the compression coil spring 58.

It is biased in the direction (rightward in Figure 1).

A pair of mounting nuts 6 are attached to the male threaded portion 17 of the nozzle base 12.
0, the mounting member 62 is fixed. Mounting member 6
2 has a substantially cylindrical shape, and a through hole 66 is formed in the center of the bottom 964. The male tapered portion 17 is inserted into the through hole 66 and fixed by a mounting nut 60 with the bottom wall 64 sandwiched therebetween.

A through hole 68 is formed in the side wall of the mounting member 62, and a flange portion 70 is formed at the rear end. A support member 72 is attached to the flange portion 70 via bolts 74 and nuts 76.

The support member 72 has a substantially cylindrical shape and has a through hole 80 in the center of the bottom wall 78.
A flange portion 82 is formed at the rear end. The threaded portion 5 of the rod member 44 is inserted into the through hole 80.
2 penetrates and protrudes rearward (to the right in Figure 1).

A maximum injection amount adjusting nut 8 for positioning the valve body 36 in the second position is provided in the threaded portion 52 on the front side of the through hole 80.
4 is screwed together with a lock nut 86. The maximum injection amount adjustment nut 84 and the lock nut 86 are tightened together and fixed to the threaded portion 52 as a double lock nut. The maximum injection amount adjusting nut 84 engages with the bottom wall 78 of the support member 72 when the rod member 44 slides rearward by a set amount to limit the amount of sliding of the rod member 44.

A bimetal 88 serving as an operating mechanism for the valve body 36 is attached to the flange portion 82 of the support member 72. The bimetal 88 is formed to be convexly curved rearward at room temperature, and is always brought into contact with the rear end of the rod member 44 (threaded portion 52) by the biasing force of the compression coil spring 5.

:jAs shown in figure S4, after bimetal 88 -
A heater 90 is attached to each side, and the heater 90 is further connected to an electronic control circuit 92 via a drive circuit 122, and is supplied with power by signals from the electronic control circuit 92. Thereby, the heater 90 generates heat according to the amount of electric power, and the bimetal 88 is curved forward in a convex manner due to thermal expansion. Here, when the heater 90 is energized, the bimetal 88 presses the rod member 44 against the biasing force of the compression coil spring 58 and slides it forward (leftward in FIG. 1), and the rod member 44 is further compressed. The valve body 36 is slid within the distributor 26 against the biasing force of the coil spring 42, thereby moving the needle portion 38 of the valve body 36 in a direction toward the injection port 18.

A small diameter portion 46 of the rod member 44 is attached to the side wall of the nozzle base 12.
A fuel supply elbow 94 is connected to the corresponding position. The fuel supply elbow 94 has a cross-sectional shape, and has a fuel supply hole 96 that communicates with the inner hole 13 of the nozzle base 12 formed therein. This fuel supply elbow 94 is connected to an electromagnetic pump via a pressure relief valve (not shown).

Therefore, the fuel pressure-fed by the electromagnetic pump is maintained at a constant pressure by the pressure relief valve and reaches the inner hole 13 from the fuel supply elbow 94, and then further to the distributor 2.
The fuel is injected from the injection port 18 of the nozzle 16 through the fuel passage portion 30 and the groove 32 shown in FIG.

Attach the spark plug 98 or holder 1 directly above the nozzle base 12.
It is attached via 00. The spark plug 98 is a high-voltage discharge ignition part, and the discharge part at the tip is located immediately above the injection port 18. The spark plug 98 is connected to an ignition transformer (not shown) for generating high voltage.

The variable injection amount nozzle 10 configured as described above is surrounded by a cylindrical raft tube 101.

The electronic control circuit 92, as shown in FIG.
02, ROM104, RAM I O6, input port 1
08, an output port 110, and a bus 112 such as a data bus or a control bus connecting these ports. The input boat 108 is connected to a rotation speed sensor 121 attached to a fan motor 124 that pumps air toward the nozzle 16, and also connected to an A/D converter 11.
4. Hot air temperature sensor 11 via multiplexer 116
8 and a nozzle position sensor 120 are connected. C.P.
U102 is a multiplexer 116 and an A/D converter 11
4, the outputs of the hot air temperature sensor l18 and the nozzle position sensor 120 are sequentially converted into digital data and stored in the RAM 106. A signal line for the fan motor 124 is connected to the output port llo via the drive circuit 102, and the CPU 102 controls the fan motor 124 by controlling the drive circuit 122. The rotation speed of the fan motor 124 is detected by the rotation speed sensor 121, and is inputted to the input boat IO8. The ROM 104 stores in advance a control routine program which will be explained below.

Next, the operation of this embodiment will be explained according to the flowchart of FIG.

First, in step 200, the burner is ignited. That is, when the operation button is operated to start the gun type burner, the ignition transformer is activated and the spark plug 98 starts discharging. Furthermore, after the set time has elapsed, the electromagnetic pump operates and fuel begins to be supplied. The fuel supplied from the electromagnetic pump is maintained at a constant pressure by the pressure relief valve, reaches the inner hole 13 from the fuel supply elbow 94, and then passes through the fuel passage part 30 and groove 32 of the distributor 26 to the nozzle 1.
The fuel is injected from the injection port 18 of No. 6, enters the ignition system, and is ignited by the spark plug 98.

When the gun type burner is ignited in step 150, the discharge by the ignition plaque 98 is stopped in preparation for the next ignition.
Fuel injection from the injection port 18 is performed continuously. Furthermore, since an O-ring 50 for fuel sealing is arranged in the center of the rod member 44, the fuel that has reached the inner hole 13 from the fuel supply elbow 94 will not leak out from the rear of the nozzle base 12.

In the next step 202, the hot air temperature T detected by the hot air temperature sensor ttS is read from the RAM.
In step 04, this hot air temperature T is compared with a preset temperature TO.

If T≧To, fuel is injected from injection port 1B! 1″
It is determined that it is necessary to decrease L, and the process proceeds to step 206, where the amount of electric power from the drive circuit to the heater 90 is increased, and the heater 90 is adjusted to 9. Heat it up.

As shown in FIG. 4, the heat generated by the heater 90 causes the bimetal 88 to thermally expand and curve convexly toward the rod member 44 (to the left in FIG. 1). Therefore, the bimetal 88 pushes the rod member 44 forward against the biasing force of the compression coil spring 58, and at the same time, the rod member 44 pushes the valve body 36 forward against the biasing force of the compression coil spring 42. make it slide. Therefore, the needle portion 38 formed at the tip of the valve body 36 moves toward the injection port 18, reducing the opening area. Since the pressure of the fuel supplied into the nozzle 16 is kept constant, the amount of fuel injected decreases as the opening area of the injection port 18 decreases. In this case, since the needle portion 38 is moved by the thermal expansion of the bimetal 88, the opening area of the injection port 18 decreases continuously without changing intermittently. Therefore, the amount of fuel injected from the injection port 18 also changes continuously as the opening area changes depending on the cardiac pressure or the amount of current applied.

Due to the curvature of the bimetal 88, the valve body 36 further increases by 1ff.
When the moving needle part 38 is pushed into the injection port 18 and reaches the set minimum injection amount, the minimum injection amount adjustment nut 5
4 engages and abuts against the rear end surface of the nozzle base 12, thereby preventing the rod member 44 from sliding.

Therefore, the movement of the needle portion 38 is also stopped, and the minimum amount of fuel necessary to be injected from the injection port 18 is ensured.

In the next step 208, the amount of movement of the rod member 44 according to the nozzle opening degree is detected from the nozzle position sensor, and the fuel injection amount F is calculated based on this. When the fuel injection amount F is calculated, in the next step 210, the air supplied by the fan motor 124: iQ is calculated so that a predetermined air-fuel ratio (theoretical air-fuel ratio) is achieved, and then in step 212, the air supplied by the fan motor 124 is The rotation speed NEo is determined, and the process moves to step 214. In step 214, the rotation speed NE of the fan motor 124 is read from the rotation speed sensor 121, and the process moves to step 216, where the set rotation @NE determined in step 212 is compared with the current rotation speed NE. If NEo>NE, the process moves to step 218, where the rotation speed of the fan motor 124 is increased, and NEo<NE.
In this case, the process moves to step 220 and the fan motor 124
Decrease the rotation speed. If NEo=NE, step 218 or step 220 is skipped, the current rotational speed is maintained, and the process proceeds to step 202. This makes it possible to always maintain the stoichiometric air-fuel ratio regardless of changes in the fuel injection amount.

Next, a case will be described in which the amount of fuel injected from the injection port 18 is increased.

If it is necessary to increase the fuel injection amount, that is, step 2
If it is determined in step 04 that it is TNT, the process moves to step 207, where the amount of electric power from the drive circuit 122 is stopped or reduced, and then the process moves to step 208. As a result, the heat generated by the heater 90 is stopped or reduced. heater 90
The bimetal 88 curves convexly toward the opposite side of the rod member 44 (toward the right in FIG. 1) as the amount of heat generated by the bimetal 88 stops or decreases. Therefore, the rod member 44 slides rearward due to the biasing force of the compression coil spring 58, and at the same time, the valve body 3
6 slides rearward by the biasing force of the compression coil spring 42. Therefore, the needle portion 38 formed at the tip of the valve body 36 moves in a direction away from the injection port 18, increasing the opening area. Since the pressure of the fuel supplied into the nozzle 16 is kept constant, the amount of fuel injected increases as the opening area of the injection port 18 increases.

In this case as well, since the needle portion 38 is moved by the bimetal 88, the opening area of the injection port 18 increases continuously without changing intermittently. Therefore, as the opening area changes, the amount of fuel injected from the injection port 18 also changes continuously.

Due to the curvature of the bimetal 88, the valve body 36 further slides, and when the set maximum injection amount is reached, contrary to the needle portion 38 and the injection port 18, the maximum injection amount adjustment nut 84 engages with the bottom wall 78 of the support member 72. The rod member 44 is prevented from sliding due to the abutment. Therefore, the movement of the needle portion 38 is also stopped, and the maximum amount of fuel injected from the injection port 18 is limited.

After such an increase in the fuel injection amount, the control from step 208 to step 220 is performed, so the nozzle position sensor detects the increase as described above, and the rotation speed of the fan motor 124 is controlled (in this case, the rotation speed is increased). Thus, a predetermined air-fuel ratio (stoichiometric air-fuel ratio) can be maintained.

In this way, in this embodiment, substantially one of the injection ports 18
3110 The needle part 38 that determines the shape is made of bimetal 8.
In order to move continuously due to the thermal expansion of 8, the injection port 1
The fuel injection amount determined by the opening area of No. 8 can be continuously and stably adjusted, and can be set to an arbitrary injection amount, and the fan motor rotation speed is also controlled according to this injection amount. After that, the air-fuel ratio does not change,
It is possible to always maintain a predetermined air-fuel ratio. Moreover, since stable combustion can be achieved with small combustion even at the time of ignition, noise at the time of ignition can also be reduced.

In this embodiment, the bimetal 88 is formed to be curved convexly in the direction of the nozzle 16 at room temperature, but is not limited to this.
It may also be an a-formation formed by convexly curving in the opposite direction. Alternatively, the bimetal 88 may be made of a shape memory alloy.

Furthermore, the moving means for moving the valve body in the axial direction may have the structure shown in FIGS. 7 to 14. Below, the structure A in each drawing will be explained individually, or the same reference numerals will be given to the parts that are basically the same as those in the above-mentioned embodiment, and the explanation thereof will be omitted.

FIG. 7 shows an embodiment consisting of a motor (step motor) 126 as a moving means and a cam 128 fixed to the output shaft of the motor 126. When the cam 12B is rotated by the motor 126, it engages with the valve body 36. The rod member 44 is moved.

Also, the :jSB diagram shows oil 132 inside the cylinder 130.
In this example, the oil 132 is injected, the heater 90 generates heat, the oil 132 expands, and the rod member 44 is moved via the piston 134.

Next, FIG. 9 shows an embodiment in which the pinion 136 is rotated by a motor (step motor) 138 to move the rack 140 linearly, thereby moving the rod member 44.

FIG. 10 shows an embodiment in which a diaphragm 144 moves a piston 146 by air supplied from a pneumatic device m l 42, thereby moving the rod member 44.

In addition, FIG. 11 shows the cylinder 1 from the hydraulic bag fi148.
The oil is fed into the cylinder 1 by drawing the oil fed into the cylinder 1.
This is an embodiment in which the rod member 44 connected to the piston 152 is moved by moving the piston 152 disposed within the piston 50.

Next, FIG. 12 shows a step motor that uses a step motor to rotate the rotor 156 in the forward or reverse direction by changing the current supply to the stator coil 154 according to a signal from an electronic control circuit, and then rotates the rod member 44 through a screw jack mechanism. This is an example in which it is moved.

FIG. 13 also shows a spiral groove 16 on the surface of a cylindrical member 160 connected to the output shaft of a motor (step motor) 158.
2, and by rotating the cylindrical member 160 by the motor 158, the pin 164 on the rod member 44 is inserted into the groove 1.
62, thereby moving the rod member 44.

FIG. 14 shows an embodiment in which a plunger 168 of a solenoid 166 is disposed coaxially with the end surface of the rod member 44, and the rod member 44 is moved by the axial movement of the plunger 168.

The gun type burner of this embodiment is not only suitable for commercial use (for example, for drying grains), but also can be applied to domestic hot water boilers. In this case, the air-fuel ratio does not change whether it is a small combustion or a large combustion, so the change in the hot water temperature is reduced.

[Effects of the Invention] As explained above, the air-fuel ratio control device for a combustor according to the present invention can control the fuel injection amount at the fuel injection port without changing the fuel supply pressure, and can control the fuel injection amount according to the fuel injection amount. It has the excellent effect of being able to control the amount of air to achieve a predetermined air-fuel ratio. Further, by using the moving means applied in this embodiment, there is an effect that the fuel injection opening and opening can be changed continuously. ′

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the variable injection amount nozzle according to this embodiment, Fig. 2 is an enlarged sectional view of the nozzle tip of Fig. 1, Fig. 3 is a perspective view of the main part of Fig. 1, and Fig. 4 5 is a control block diagram, FIG. 6 is a control flowchart, and FIGS. 7 to 14 are operation explanatory diagrams of the moving means according to other embodiments. . IO... Variable injection amount nozzle, 16... Nozzle. 18... Injection port, 36... Valve body, 92... Electronic control circuit.

Claims (1)

[Claims] (1) An air-fuel ratio control device for a combustor that mixes and burns fuel injected from a fuel injection port and air, the device having a first position where the fuel injection port is fully opened and a first position where the fuel injection port is fully closed. a valve element movable between a second position; a moving means for moving the valve element to a position corresponding to a predetermined fuel injection amount; An air-fuel ratio control device for a combustor, comprising: control means for controlling the air-fuel ratio to a predetermined value by controlling the amount of air supplied.