JPH0631315Y2 - Combustion heater combustion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a combustion control device for a combustion heater used in a vehicle or the like, and more particularly to a combustion control device for a combustion heater that enables reliable fire extinguishing.

(Prior Art and Its Problems) Conventionally, in a combustion control device for a combustion type heater used for heating a vehicle, keeping heat of food, etc., generally, when a fire is extinguished, that is, when the combustion of the heater is stopped, a fuel supply pump is used. Immediately after the fuel supply is stopped, the fuel impregnated in the wick of the combustor remains, so it is necessary to supply air to the combustor until the fuel burns out even after the fuel supply is stopped. A technique for supplying air with a constant air flow rate is proposed in, for example, Japanese Utility Model Laid-Open No. 58-15861. However, the residual fuel gradually decreases, and the amount of fuel vaporization gradually decreases from the stop of fuel supply to complete extinction.
If the amount of air blown is constant, the amount of air becomes excessive, so the air-fuel ratio in the combustor becomes lean and blue-white smoke is emitted, harmful components are discharged, and the fire blows out during combustion. It was In particular, when the blowout occurs, the fuel still remains in the wick, and immediately after the blowout, white smoke is generated due to unburned gas, and the residual fuel is carbonized by the residual heat of the heater. Since it adheres to the wick, there is a problem that durability and ignitability are deteriorated.

On the other hand, after the fire is completely extinguished, it is necessary to further supply air to perform scavenging in order to cool the heater and discharge the vaporized gas of the residual fuel from the viewpoint of safety.

The present invention has been made in view of the above problems and demands, and completely burns the residual fuel after the fuel supply is stopped to prevent the emission of harmful components and improve the durability and ignitability of the wick. An object of the present invention is to provide a fuel control device for a combustion type heater, which is capable of quickly and sufficiently cooling the type heater and discharging the vaporized gas of residual fuel.

(Means for Solving Problems) In order to solve the above problems, the present invention provides a combustor, fuel supply means for supplying fuel to the combustor, and air supply for supplying air to the combustor. In a combustion control device for a combustion type heater including means, after the input of a combustion stop command signal, the supply of fuel by the fuel supply means is stopped, the air supply means is operated, and the air amount immediately before the stop signal is input. For a first predetermined time, and after a lapse of the first predetermined time, gradually decreasing to a first predetermined air amount for a second predetermined time, and then a second predetermined air amount larger than the first predetermined air amount. The fire extinguishing control means for supplying the amount of air is provided.

(Operation) When the combustion stop command signal is input, the fire extinguishing control means stops the fuel supply by the fuel supply means and causes the air supply means to supply the air amount immediately before the fuel supply stop signal is input for the first predetermined time. Then, after the first predetermined time has elapsed, the second predetermined air amount is gradually reduced to the first predetermined air amount over the second predetermined time, and then the second predetermined air amount larger than the first predetermined air amount is supplied. As a result, the residual fuel in the combustor is completely combusted, and the heater after cooling and the exhaust of the vaporized gas of the residual fuel are discharged quickly and sufficiently.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall structure of a combustion type heater provided with a combustion control device according to an embodiment of the present invention. The combustion type heater is mounted on a heating car or the like for transporting food etc. in a warm state. It is used to warm the inside of the refrigerator. In FIG. 1, reference numeral 1 denotes a combustor that ignites and burns a mixture of vaporized liquid fuel and combustion air in a combustion chamber 3 inside a combustion cylinder 2 to generate a high-temperature combustion gas. The combustor 1 includes a combustion tube 2 which forms a combustion chamber 3 therein, a wick 4 impregnated with liquid fuel, and a passage forming member 5 having a fuel passage 5a for supplying the wick 4 with liquid fuel. The glow plug 6 for igniting the vaporized fuel is a main component.

A large number of air inflow holes 2a are formed in the outer peripheral wall of the combustion tube 2, and the end opening of the combustion tube 2 is closed by a disc-shaped wick 4 formed of ceramic fiber, for example. A glow plug 6 is attached to a case 7 that covers the periphery of the combustion cylinder 2, and the tip of the glow plug 6 projects into the combustion chamber 3. The glow plug 6 is electrically connected to an electronic control unit (hereinafter referred to as “ECU”) 8 as a control means described later, and the voltage applied to the glow plug 6 is variably controlled by an output signal from the ECU 8. It has become so.

A combustion air supply blower (air supply means) 10 is disposed at the air supply port 9 of the combustor 1, and the blower 10 is responsive to an output signal from an electrically connected ECU 8 to form a combustion chamber 3
Is supplied with combustion air (Q _{1 to} Q _{4 in} FIG. 3). The high-temperature combustion gas generated in the combustion chamber 3 passes through the combustion pipe 25 of the heat exchanger 23 arranged adjacent to the combustor 1 and the case 7
It passes between the inner fins 11 provided on the inner peripheral wall of the cylindrical portion 7a, and is discharged to the outside from the discharge port 12.

A cover 13 is provided on the outside of the cylindrical portion 7a of the case 7, and a heating air supply blower 15 is provided at the blow-in port 14 of the cover 13. Amount of air supplied from the heating air supply blower 15 (HI, L in FIG. 3)
O) is provided with this blower 15. The air supplied from the air supply blower 15 is adjusted according to the output signal from the ECU 8 electrically connected to the heating air supply blower 15, and passes through the outer fins 26 heated by the combustion gas. After the heat is exchanged, the air is sent from the outlet 16 of the cover 13 into a duct (not shown), and the hot air inlet 17
It is sent to the greenhouse 17 from a.

The fuel passage 5a of the passage forming member 5 communicates with a fuel tank 20 via a pipe 18 and a fuel supply pump 19 as fuel supply means. The fuel supply pump 19 is the ECU 8
The fuel supply amount (F ₁ , F _{2 in} FIG. 3) is controlled according to the output signal from the ECU 8, and the amount of fuel supplied from the fuel passage 5a to the wick 4 is determined. .

An ignition sensor (ignition detection means) SI for detecting whether or not the air-fuel mixture is ignited in the combustion chamber 3 is arranged in the vicinity of the glow plug 6 of the case 7 with its tip protruding into the combustion chamber 3. Has been done. Also, the warm air outlet 17b of the greenhouse 17
A temperature sensor S2 that detects the room temperature in the greenhouse 15 is attached to the inner wall in the vicinity, and the room temperature signal detected by the sensor S2 is sent to the ECU 8.

A heat exchanger temperature sensor S3 for detecting the temperature of the heat exchanger 23 itself is arranged in the heat exchanger 23, and an output signal from the sensor S3 is sent to the ECU 8.

It is determined that the ECU 8 has an abnormality in the operation panel 21 that outputs a signal indicating the instruction content of the driver such as the ignition start command, the set (target) temperature in the greenhouse 17, the combustion stop command, and the combustion heater. At this time, the abnormality display (warning) device 22 for notifying the driver of the abnormality, and further the battery voltage detection means including resistors 24a, 24b for dividing the voltage of the battery (voltage application means) 24 to detect the fluctuation of the battery voltage are provided. Each is electrically connected.

The ECU 8 controls the glow plug 6, the combustion air supply blower 10, the fuel supply pump 19, and the air supply blower 15 based on the signals from the sensors S1 to S3 and the operation panel 21, which will be described later. Drive control is performed according to FIG.

Specifically, the ECU 8 mainly includes a multiplexer 8a, an A / D converter 8b, a microcomputer 8c, and a plurality of drive elements 8d, and outputs the output signals of the sensors S1 to S3 and the battery voltage input to the multiplexer 8a. The voltage signal indicating the fluctuation is sequentially A / D converted by the A / D converter 8b, and then the microcomputer 8c.
Is supplied to. The microcomputer 8c supplies the voltage applied to the glow plug 6, the fuel supply amounts F ₁ and F ₂ by the fuel supply pump 19, and the air supply by the combustion air supply blower 10 based on the above-mentioned sensors S1 to S3, the battery voltage signal, and the like. The amounts Q _{1 to} Q ₄ and the blown air amounts HI and LO by the air supply blower 15 are determined, and signals representing the determined values are sent to the glow plugs 6 via the respective drive elements 8d,
The fuel is supplied to the fuel supply pump 19, the combustion air supply blower 10, and the air supply blower 15 to perform desired control.

Further, the microcomputer 8c, duty map Q ₁ duty ratio changes in accordance with the change in the power supply voltage to control the air supply amount (voltage of the battery 24) of the blower 10 after the fuel supply stop, which will be described later ~Q ₄ (See Fig. 4)
Is stored in advance.

Next, a specific operation of the combustion control device for the combustion type heater configured as described above will be described with reference to FIGS. 2 to 5.

FIG. 2 is a program flow chart for executing the combustion operation of the combustion heater.

First, in step S1, it is determined whether or not combustion of the combustion type heater should be performed based on the signals of the sensors S1 to S3. When this answer is negative (No), the air flow rate Q ₃ of the combustion air supply blower 10 and the heating air supply blower 1
The amount of air blown in No. 5 is set to LO to make the suspension state (step S
2) Return to step S1.

When the answer to step S1 is affirmative (Yes), ignition control for igniting the glow plug 6 is performed in step S3, and stable combustion control is performed so that the room temperature of the greenhouse 15 is maintained at the target set temperature after ignition. Perform (step S4).

Next, in step S5, for example, the heater switch of the operation panel 21 is off or the engine key is removed,
Or the heat exchanger temperature sensor S3 shows an abnormal value,
It is determined whether or not the combustion of the combustion type heater should be immediately stopped when a failure occurs in the control system. When the answer is negative (No), the process returns to step S4 to continue the stable combustion control, and when the answer is affirmative (Yes), the process proceeds to step S6 to perform the extinguishing control according to the present invention by the extinguishing control means described later. This fire extinguishing control is control for completely burning the fuel remaining in the wick 4 after stopping the fuel supply by the fuel supply pump 19, cooling the heater, and scavenging the vaporized gas of the residual fuel.

After the execution of the fire extinguishing control, the process proceeds to step S7, and it is determined whether or not the blowers of the heater, that is, the operations of the combustion air supply blower 10 and the heating air supply blower 15 should be completely stopped. When the answer is negative (No), the process returns to step S1 and the present program is repeated. On the other hand, if the answer is affirmative (Yes), the operation proceeds to step S8 and the blowers 10 and 15 are turned on.
Set to FF and end this program.

Next, the procedure of the fire extinguishing control in step S6 will be described with reference to FIG.

First, when the condition for extinguishing control at the time point T ₀ is satisfied from the combustion control with the maximum fuel supply amount F ₁ and the maximum air supply amount Q ₁ , the combustion supply amount becomes _zero at the time point T ₀ (OFF in FIG. 3). and then, maintaining the combustion air supply blower 10 and the air volume in the T ₀ t ₁ hour from the time to T ₁ time (first predetermined time) the amount Q ₁ corresponding to the fuel supply amount F ₁ T ₀ point just before To operate. Then, _{t 2} from _{T 1} point to _{T 2} time
The air flow rate is linearly gradually decreased from Q ₁ to a predetermined amount Q ₄ set in advance over a time period (second predetermined time period). That is, as the amount of fuel remaining in the wick 4 decreases with the passage of time, the amount of vaporization of the residual fuel also decreases, so that the amount of combustion air supplied also decreases as the amount of vaporization of the fuel decreases. Then, after the air flow rate is reduced to Q ₄ at time T _{2, the} air flow rate Q ₄ is maintained for t ₃ hours (third predetermined time) from time T _{2 to} time T ₃ and the wick 4 Almost completely burns the residual fuel.

T ₃ time, the air blowing amount for discharge of vaporized gas cooling and residual fuel heater is increased to the blowing rate Q ₄ greater than for example air volume Q _3, T to ₄ times, namely t ₄ hours (fourth The blower 10 is operated with the air flow rate Q _{3 for a} predetermined time.
T ₄ time after by the procedure of step S7 and subsequent of the second diagram of the program, the blowing amount Q ₃ of the blower 10
Or it is determined to be OFF.

On the other hand, during the operation of the blower 10, the heating air supply blower 15 cools the heat exchanger 23, so that it is operated at the maximum air flow rate HI from the time point T _{0 to the} time point T ₄ , and after the time point T ₄ , Similar to the blower 10, the blow rate of the blower 15 is determined to be either LO or OFF by the procedure from step S7 onward of the program.

Further, the amount of air blown by the blower 10 at time T ₀ is the fuel supply amount F ₂
In the same manner as described above, the blower 10 maintains the respective blown air amounts Q ₂ and Q ₃ even when the blower air amount Q ₂ corresponding to the above is controlled or when the blower air amount Q ₃ during ignition control is controlled. After being driven to the time point T ₁ as it is, the blown air amount is gradually reduced to the predetermined amount Q ₄ for t ₂ hours, and thereafter, the drive control is performed in the same manner as described above.

As shown in FIG. 4, the blower 10 is controlled by the macro computer 8c at a duty ratio (here, a ratio of on-time to off-time within one cycle) according to a change in power supply voltage. In addition, the desired air flow rates Q _{1 to} Q ₄ are always obtained. In particular, the duty ratio from the time point T _{1 to the} time point T ₂ is calculated by the following equation so as to linearly decrease within the time period t ₂ .

D = D _B + (D _A −D _B ) × t / t ₂ (1) where D _A is the air flow rate Q ₁ , Q ₂ of the blower 10 immediately before the fuel supply amount is set to zero (OFF) or duty ratio for supplying Q _{3, D B} are _T 2 -T ₃ between the duty ratio for supplying air volume _{Q 4} in, _{t 2} is _T 1 -T ₂ between the time (linear control time), t is linear control time Remaining time (remaining time of the timer T _M2 that counts t ₂ hours).

Next, a specific procedure of the above-described fire extinguishing control will be described with reference to the fire extinguishing control subroutine shown in FIG.

First, the fuel supply from the fuel supply pump 19 is stopped (step 601), the blowing amount of the heating air blowing blower 15 is set to HI (step 602), and the count value of the delay timer T _M1 is set to the predetermined time t ₁ . Yes (Step 60
3).

Next, in step 604, it is determined whether or not the count value of the set timer T _M1 has become zero, and if the answer is negative (No), the process proceeds to step 605 to count down the timer T _M1 . Combustion air supply blower 10
Is driven at the duty ratio D _A (step 606), the process returns to step 604, and steps 604 to 606 are repeated until the count value of the timer T _M1 becomes zero.

When the answer to step 604 is affirmative (Yes), that is, when it is determined that t ₁ time has elapsed since the fuel supply was stopped, the routine proceeds to step 607, where the count value of the delay timer T _M2 is set to the predetermined time t. Set to ₂ . Next, in step 608, it is determined whether or not the count value of the timer T _M2 has become zero, and if the answer is negative (No), the timer T _M2 is counted down (step 60
9), the blower 10 is driven with the duty ratio D calculated so as to linearly decrease by the equation (1) (step 61).
0), the process returns to step 608, and steps 608 to 610 are repeated until the count value of the timer T _M2 becomes zero.

When the answer to step 608 is affirmative (Yes), that is, when it is determined that t ₂ time has elapsed, the routine proceeds to step 611, where the count value of the delay timer T _M3 is set to the predetermined time t ₃
, And proceed to step 612. In step 612, it is determined whether or not the count value of the timer T _M3 has become zero, and if the answer is negative (No), the timer T _M3 is counted down (step 613) and the blower 10 is set to the duty ratio. Drive with the ratio D _B (air flow rate Q ₄ ) (step
614), the process returns to step 612 and steps 612 to 614 are repeated until the count value of the timer T _M3 becomes zero.

When the answer to step 612 is affirmative (Yes), the process proceeds to step 615, the count value of the delay timer T _M4 is set to the predetermined time t ₄ , and the process proceeds to step 616. In step 616, it is determined whether or not the count value of the timer T _M4 has become zero. If the answer is negative (No),
The count value of the timer T _M4 is counted down (step 617), the blower 10 is driven with a duty ratio Dc (air flow rate Q ₃ ) larger than the duty ratio D _B (step 618), the process returns to step 616, and the timer T Steps 616 to 618 are repeated until the count value of _M4 becomes zero.

When the answer to step 616 is affirmative (Yes), this fire extinguishing control subroutine is ended.

Thus, the combustion air supply blower 10 after the fuel supply is stopped
By linearly decreasing the air flow rate of
Combustion air is supplied according to the amount of vaporization of the remaining fuel to prevent harmful components from being discharged and the durability and ignitability of the wick can be improved, and after the supply air amount is gradually reduced, the air amount is increased for a predetermined time. By doing so, the heater can be cooled and the vaporized gas of the residual fuel can be discharged quickly and reliably.

In the above embodiment sets the air volume increase time of the blower 10 of T ₃ after the time point the predetermined time t _4, but as shown in FIG. 6, or the detected temperature of the heat exchanger temperature sensor S3 becomes lower than a predetermined temperature The air flow rate increase control may be performed depending on whether or not the air flow rate is increased.

An embodiment of fire extinguishing control according to the heat exchanger temperature will be described below with reference to FIG. Since the fire extinguishing control subroutine of FIG. 6 differs from the above-described subroutine of FIG. 5 only in steps 615 to 618 of FIG. 6, only different steps 715 to 717 are shown in FIG. Illustration and description of steps 601 to 614 are omitted.

According to this embodiment, when the answer to step 612 in FIG. 5 is affirmative (Yes), that is, when the count value of the delay timer T _M3 becomes zero, the process proceeds to step 715 and the blower 10 is set to the duty ratio. Drive at the ratio Dc (air flow rate Q ₃ ),
It is determined whether or not the ignition sensor S1 has detected the extinction of the combustion chamber 3 (step 716). When the answer is negative (No), the process returns to step 715 to execute the same step, and when the answer is affirmative (Yes), the process proceeds to step 717 and the temperature detected by the heat exchanger temperature sensor S3 is a predetermined temperature (for example, 80 °). C) Determine whether or not the following. When the answer is negative (No), the procedure returns to step 715, and steps 715 and 716 are executed. When the answer is affirmative (Yes), it is determined that the combustion heater is sufficiently cooled and the vaporized gas is sufficiently scavenged. Finish the subroutine.

(Effects of the Invention) As described above, the present invention provides a combustion heater including a combustor, a fuel supply unit for supplying fuel to the combustor, and an air supply unit for supplying air to the combustor. In the combustion control device, after the combustion stop command signal is input, the supply of fuel by the fuel supply means is stopped, the air supply means is caused to supply the air amount immediately before the stop signal is input for a first predetermined time, Fire extinguishing control means for supplying a second predetermined air amount larger than the first predetermined air amount after gradually decreasing to the first predetermined air amount for a second predetermined time after the first predetermined time has elapsed. Since it is equipped with, it is possible to completely burn the fuel remaining in the combustor after stopping the fuel supply, prevent the emission of harmful components, improve the durability and ignitability of the wick, and cool and retain the combustion heater. Evaporate fuel vapors quickly and Can be done enough.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a combustion heater having a combustion control device according to an embodiment of the present invention, FIG. 2 is a program flow chart showing a procedure of combustion control of the combustion heater, and FIG. 4 is a timing chart showing the operation of each device, FIG. 4 is a diagram showing a duty ratio map stored in the microcomputer, FIG. 5 is a fire-extinguishing control subroutine according to the first embodiment, and FIG. 6 is according to the second embodiment. It is a fire-extinguishing control subroutine. DESCRIPTION OF SYMBOLS 1 ... Combustor, 10 ... Combustion air supply blower (air supply means), 19 ... Fuel supply pump (fuel supply means), 8 ... E
CU (fire extinguishing control means).

Claims (1)

[Scope of utility model registration request] 1. A combustion control device for a combustion type heater comprising a combustor, fuel supply means for supplying fuel to the combustor, and air supply means for supplying air to the combustor. Is stopped, the supply of fuel by the fuel supply means is stopped, the air supply means is caused to supply the amount of air immediately before the stop signal is input for a first predetermined time, and after the first predetermined time elapses, 2 is gradually reduced to the first predetermined air amount for a predetermined time of 2, and then the second air amount larger than the first predetermined air amount is used.
A combustion control device for a combustion heater, comprising: a fire extinguishing control means for supplying a predetermined amount of air.