JPH03118209A - Combustion controller of combustion type heater for vehicle - Google Patents

Abstract

PURPOSE:To enhance safety by stopping of fuel supply to a combustion unit with the judgement that a heat exchanger is in overheat conditions when the temperature of the heat exchanger is over a first predetermined temperature while by stopping operation of a heater with the judgement of abnormality when it is over a second specified temperature (lower than the first predetermined temperature). CONSTITUTION:A combustion type heater unit 3 has a combustion unit 1 which generates combustion gas at high temperature by combusting mixed gas or vaporized liquid fuel and combustion air, the combustion gas generated at the combustion unit 1 and air for warming are heat-exchanged with a heat exchanger 2, and high temperature warming air is circulated between the heat exchanger 2 and a heat retaining chamber 5, with operation of a blower 7. In this case when the temperature of the heat exchanger 2 is over a first predetermined temperature, it is judged that the heat exchanger 2 is in overheat conditions, and fuel supply to the combustion unit 1 is stopped. When it is over a second predetermined temperature (lower than the first temperature), on the other hand, it is judged that the heater unit 3 is in abnormal conditions and operation of the heater unit 3 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a combustion control device for a combustion type heater for a vehicle, and particularly to a combustion control device that reliably detects abnormality in the heater.

(Prior Art) Conventionally, a vehicle has a heat exchanger disposed around a combustor, and air introduced into the heat exchanger by a blower is heated by the combustor and supplied into the vehicle compartment or luggage compartment. As a combustion control device for a combustion type heater, a temperature sensor is installed in the heat exchanger, and the amount of fuel supplied to the combustor and the amount of air blown by the blower are controlled according to the heat exchanger temperature detected by the temperature sensor. A system that prevents overheating of the heat exchanger through variable control has been proposed (
(Patent Application No. 63-297418).

In the control device according to this proposal, when the heat exchanger temperature becomes equal to or higher than a predetermined value, it is determined that the heat exchanger is in an overheating state, and the fuel supply to the combustor is stopped;
After that, the heat exchanger temperature decreases, and when it becomes below the predetermined temperature, fuel is supplied to the combustor again.

However, if the blower stops due to a malfunction or the like and no air is blown, or if the amount of air blown decreases abnormally, the temperature of the heat exchanger may suddenly rise even when the fuel supply to the combustor is stopped. , the heat exchanger may overheat. Even in such a case, the above technique operates the control device, but there is a problem in terms of safety.

On the other hand, as a combustion control device for a combustion type heater for a vehicle that detects a failure of a blower, for example, there is a device disclosed in Japanese Patent Laid-Open No. 62194928. According to this technique, an overheat prevention means is provided which detects the current of the blower motor of the blower using a resistance and stops the combustor when the blower motor current falls outside a set value range.

(Problem to be Solved by the Invention) However, the blower failure detection method disclosed in the above-mentioned Japanese Patent Application Laid-open No. 194928/1983 has problems such as power loss and high cost due to the resistor, and furthermore, it is detected by fluctuations in battery voltage, etc. There is a problem that accuracy deteriorates.

Furthermore, according to the above-mentioned conventional technology, only an overheating state is assumed when the blower suction port becomes temporarily semi-occluded due to dust or the like and the air flow rate decreases, and when the blower stops operating. Since this method does not assume that

The present invention has been made in view of the above circumstances, and detects a fatal abnormality in a combustion type heater such as a blower failure using a low-cost and simple means without installing any special equipment, and provides heat exchanger. An object of the present invention is to provide a control device for a combustion type heater for a vehicle, which ensures safety by preventing overheating and damage to the heater.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes a combustor, a heat exchanger provided around the combustor, and a temperature sensor that detects the temperature of the heat exchanger. , a combustion control device for a combustion type heater for a vehicle, comprising a blower means for introducing air into the heat exchanger, and a fuel supply means for supplying fuel to the combustor, wherein the fuel is supplied by the fuel supply means. In a combustion control device that controls the amount of fuel supplied and the amount of air blown by the blower means, it is determined that the heat exchanger is in an overheating state when the heat exchanger temperature detected by the temperature sensor is higher than a first predetermined temperature. and stops fuel supply to the combustor, and when the detected temperature of the heat exchanger becomes equal to or higher than a second predetermined temperature higher than the first predetermined temperature, it is determined that there is an abnormality in the combustion type heater. The combustion type heater is characterized in that the operation of the combustion type heater is stopped.

(Function) As shown in FIG. 1, the above-mentioned combustion control device for a combustion type heater for a vehicle is configured such that the temperature of the heat exchanger rises due to a decrease in the amount of air blown by the blower, and the temperature rises to the first predetermined temperature or higher. When this happens (step Sl), combustion in the combustor is stopped (step 32).

However, for example, if the blower malfunctions and stops operating, the temperature of the heat exchanger increases and the second
2 (step S3), but at this time, the operation of the combustion type heater is stopped (step 84).
.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 schematically shows the entire combustion control device for a combustion type heater for a vehicle according to an embodiment of the present invention. This combustion control device is mounted on a heating delivery vehicle that delivers foods such as bread in a warmed state, and is used to heat the insulated warehouse.

A combustion control device for a combustion heater for a vehicle includes a combustor 1 that generates high-temperature combustion gas by combusting a mixture of vaporized liquid fuel and combustion air, and a heat exchanger 2. unit 3 and control units 1 to 4 that control combustion of the heater unit 3.

In the combustion type heater unit 3, heating air is introduced into the duct 6 from the insulated warehouse 5 of the heating delivery vehicle through the inlet 6a, and the inside of the duct 6 is routed along the heat exchanger 2 into the insulated warehouse. A heating air blower 7 is provided to blow air into the air outlet 6b. The heating air from inside the heat storage 5 is blown through the duct 6 to the outlet 6b by the blower 7, and is heated by exchanging heat with the high temperature combustion gas introduced from the combustor 1 by the heat exchanger 2. It looks like this.

A combustion chamber 8a is formed in the combustion tube 8 of the combustor 1, and a short wick 9 is provided in the combustion chamber 8a, which is temporarily impregnated with the liquid fuel to be supplied. This short core 9 has a fuel tank 1
Liquid fuel in 0 is supplied through pipe 12 by fuel pump +1. This fuel pump 11 is
Fuel is supplied each time a control pulse signal is energized to the drive solenoid No. 1, and by changing the frequency of the control pulse signal, there is an OFF position where fuel supply is stopped, and an LO position where the minimum fuel supply amount is obtained. It can be controlled in three stages: the H1 position and the H1 position where the maximum fuel supply amount is obtained. The combustion tube 8 includes a glow plug 13 that vaporizes the liquid fuel impregnated in the short wick 9 and ignites and burns the mixture of the vaporized liquid fuel and combustion air.
and an ignition sensor 14 that detects ignition.

Combustion air is supplied to piping 1 by combustion air supply blower 15.
The air is supplied into the combustion chamber 8a through a large number of air inlet holes formed in the peripheral wall of the combustion tube 6 and the combustion tube 8.

The control unit 4 includes a microcomputer 20,
A multiplexer 21, an A/D converter 22, an operation panel 23 for giving commands to the microcomputer 20, and the like are provided. The microcomputer 20 includes a central control section for performing arithmetic processing, parts of various memories for storing control programs, etc., an input/output section, and the like.

The multiplexer 21 receives a signal from an internal temperature sensor 24 disposed at the inlet 6a in order to detect the temperature of the heating air introduced into the duct G from the thermal storage 5 to detect the temperature inside the thermal storage 5. An internal temperature signal, an ignition signal from the ignition sensor 14, and a heat exchanger temperature signal from a heat exchanger temperature sensor 25 attached to the outer surface of the heat exchanger 2 to prevent the heat exchanger 2 from overheating. are entered respectively.

Each signal input to the multiplexer 21 is sequentially A/
The signal is supplied to the input section of the microcomputer 20 via the D converter 22.

Output signals from each output part of the microcomputer 20 are sent to an indicator 30 that notifies the passenger when a failure occurs in the driving elements 26 to 29, the processor 77, etc.
are output respectively.

The drive element 26 supplies a pulse signal with a frequency corresponding to the output signal from the microcomputer 20 to the drive solenoid of the fuel pump 1.1, thereby adjusting the amount of fuel supplied by the fuel pump 11 to a maximum fuel supply amount 111 and a minimum fuel supply amount 111. It is configured to be able to perform switching control in three stages: fuel supply amount LO and stop OFF. That is, the amount of fuel supplied by the fuel pump 11 is determined according to the temperature inside the heat-insulating refrigerator 5 detected by the temperature sensor 24 and the temperature of the heat exchanger 2 detected by the heat exchanger temperature sensor 25. The drive element 27 is controlled to selectively operate the fuel supply amount LO1, the maximum fuel supply amount HI, or the stop OFF. It is configured to ignite by applying voltage.

The drive element 28 is configured to output a pulse signal having a duty ratio (here, the ratio of on-time within one cycle) calculated by the microcomputer 20 to the motor of the combustion air supply blower 15. There is. The blower 15
A transistor (not shown) is turned on only during the ON period of the pulse signal, and driving force is applied to the motor to rotate and blow air.

For example, like the drive element 26, the drive element 29 controls the rotational speed of the heating air blower 7 by applying a pulse signal having a frequency corresponding to the output signal from the microcomputer 20 to the drive motor of the heating air blower 7. , the amount of heating air blown by the blower 7 can be switched and controlled in three stages: maximum air amount HI, minimum air amount LO1, stop OFF. That is, the heating air blower 7
The amount of air blown by the fuel pump is set to a maximum air amount HI and a minimum air amount L so that the internal temperature of the heat storage chamber 5 maintains the set center value according to the fuel supply amount by the fuel pump and the heat exchanger temperature.
It is controlled to selectively operate either O1 or stop OFF.

The operation of the combustion control device for a combustion type heater for a vehicle according to this embodiment will be explained below with reference to FIGS. 3 to 7.

FIG. 3 is a diagram showing the control state of the temperature Trs in the heat-retaining warehouse when the heating air blower 7 is operating normally.

As shown in (c) of the same figure, at the time of startup, both the fuel supply amount and the air flow rate of the blower 7 become HI, and as time passes, the temperature S detected by the heat exchanger temperature sensor 25 ((b) of the same figure)
and the temperature TIN in the thermal storage chamber ((a) in the same figure) rises (t
between o and tt).

Here, the broken line in FIG. 2B indicates the temperature at the highest temperature part of the heat exchanger 2, while the solid line indicates the temperature at the temperature sensor 2.
5, which vary correspondingly to each other. When the temperature TIN inside the insulated refrigerator rises and reaches the center value of the set temperature (time L1), both the fuel supply amount and the blower air flow become LO, and the temperature inside the refrigerator further rises and reaches the upper limit of the set temperature. If it reaches (time shift 2)
, turn off the fuel supply amount. On the other hand, at this time, the blower air flow rate is set to III for a predetermined short period of time, and then to LO.
maintain. When the internal temperature TIN falls to the central value again (time 3), both the fuel supply amount and the blower air flow are controlled to LO. The operation is repeated to control the temperature inside the refrigerator.

However, due to a drop in battery voltage, deterioration in the performance of blower 7, etc., the wind power decreased to a level that could not be ignored, and the controlled air flow rate was set to HI.
If sufficient airflow cannot be obtained even after using blower 7,
Since the air from the heat exchanger 2 will no longer be supplied to the heat exchanger 2 with a sufficient amount of air, the heat exchanger temperature will rise. At this time, if the temperature inside the heat-insulating refrigerator is controlled only by detection by the inside temperature sensor 24, the temperature of the heat exchanger may become abnormal. Therefore, in order to prevent this, the fuel supply amount is controlled according to the procedure shown in FIG. That is, due to the internal temperature control, when the fuel supply amount is set to HI, the air flow rate of the blower 7 decreases, and the temperature S detected by the heat exchanger temperature sensor 25 rises to a predetermined temperature Tc (for example, 150° C.). (time tc1), the fuel supply amount is changed from 1-11 to LO, and then the predetermined temperature Tc' lower than Tc (for example, 140°C
) (time t C2), the fuel supply amount is set to tl 1 again, and thereafter the fuel supply amount is controlled so that the detected temperature is at least within a range of Tc or lower.

Next, if the air flow rate of the blower decreases further than in the above-mentioned state, that is, even if the temperature S detected by the sensor 25 reaches the predetermined temperature Tc and the fuel supply amount is set to LO, the temperature continues to rise. In this case, the fuel supply amount is controlled according to the procedure shown in FIG.

That is, the detected temperature becomes Tc (time tbt), and even if the fuel supply amount is changed from tl I to LO, the temperature continues to rise,
When the predetermined temperature Tb (for example, 165°C) is reached (
At time tb2), the fuel supply amount is temporarily turned off.

After that, the temperature decreases to a predetermined temperature Tb' (for example, 160°C
) (time tb3), the fuel supply amount is set to LO again, and thereafter the fuel supply amount is controlled so that the detected temperature S is at least within a range of Tb or less.

Next, a fuel supply control method when the amount of air blown by the blower 7 becomes almost completely zero will be explained based on FIG. 6.

If the blower 7 is stopped due to wear of the brushes of the motor, or the fan is damaged, so that almost no amount of air can be blown, the temperature of the heat exchanger 2 may rise abnormally, causing a safety problem.

Therefore, in such a case, it is desirable to stop the entire control device (non-recovery stop) at the same time as the abnormality is detected. That is, the temperature S detected by the sensor 25 rises above the predetermined temperature Tc (time La+), continues to rise even when the fuel supply amount is set to LO, and reaches the predetermined temperature Tb (time ta2).
If the temperature continues to rise even after the fuel supply amount is turned OFF', the temperature will be lower than the predetermined temperature Ta (for example, 200
℃) (time t a3), it is determined that an abnormality has occurred in the blower 7 such that the air flow rate becomes approximately zero, and
The entire control device is placed in a non-returnable stopped state. The non-returning stopped state is, for example, when the fuel pump 11 is turned OFF, the power supply to the glow plug 17 is cut off, the heating air blower 7 and the fuel air supply blower 15 are stopped, and the internal temperature TIN, Even when the heat exchanger temperature drops and the conditions for combustion and heating are met, the engine remains shut down without re-combusting. Preferably, at the same time as this non-returning stop, the indicator 30 is blinked to warn the occupant that the heater combustion control device is abnormal.

Further, this non-returnable stop is canceled by a reset switch (not shown) (generally not operated by the user).

Next, the microcomputer 2 that performs the control procedure described above is
The specific operation of 0 will be explained based on the program flowchart shown in FIG.

First, in step Sl, the value of the difference TIN-Ts between the internal temperature TIN of the heat-insulating refrigerator 5 and the target set temperature Ts is determined.

If the set temperature Ts is set to 18°C, for example, the internal temperature T+s will drop to a temperature lower than 17°C (TIN-'
5 (-1℃), or the temperature "+N is 17℃
If the temperature has increased from below and has not yet reached 18°C (state α), the process advances to step S2.

In step S2, it is determined what value the temperature S detected by the heat exchanger temperature sensor 25 takes with respect to the predetermined temperatures 1°C and Tc'. First, when it is determined that the detected temperature S has decreased and has become lower than the predetermined temperature 1°C' (Δ), the process proceeds to step S3, the fuel supply amount is set to HI, and the process returns to step Sl.

On the other hand, if it is determined in step S2 that the temperature S detected by the sensor 25 has increased and has become higher than the predetermined temperature 'rC (13), the process proceeds to step S5.

On the other hand, in step Sl, the internal temperature TIN increases to +4°C from the set temperature 18°C, that is, higher than 22°C, or decreases from a temperature higher than 22°C to the set temperature 1.
When it is determined that the temperature has not reached 8°C (state γ), the process proceeds to step S4, the fuel supply is temporarily stopped, and the process proceeds to step S1.
Return to

Further, when it is determined in step Sl that TIN is rising higher than 18°C but is below 22°C, or is falling below 18°C but is above 17°C (state β), the step Proceeding to S5, it is determined what value the detected temperature S of the sensor 25 takes with respect to predetermined values Tb and Tb'.If the detected temperature S is lower than Tb' (A), the process proceeds to step S6. Set the fuel supply amount to LO and step 31
Return to

On the other hand, in step S5, the detected temperature S of the sensor 25 is l'
If it is higher than b, (B) the process advances to step S7.

In step S7, it is determined whether the temperature S detected by the sensor 25 is equal to or higher than the predetermined temperature Ta, and the answer is negative (NO).
), the process proceeds to step S4, where the fuel supply is temporarily stopped and the process returns to step S]. When the answer is affirmative (Yes), that is, when the temperature S is Ta or higher, it is determined that an abnormality has occurred in the blower 7 such that the amount of air blown is approximately zero, and the combustion type heater for the vehicle is turned off. The entire control system is put into a non-returning stopped state (step S8), and the indicator 30 is flashed to warn the occupants (step S9).

Therefore, according to the present invention, it is possible to detect a fatal abnormality for the combustion heater, such as a failure of the blower 7, using only the temperature S detected by the heat exchanger temperature sensor 25, and when a failure is detected, the entire control device is activated. By setting the engine to a non-returnable stop state, it is possible to prevent wasteful consumption of fuel and the recurrence of dangerous conditions such as repeated overheating due to empty cooking.

In the two consecutive embodiments, the detected temperature S of the heat exchanger temperature sensor 25 is used to detect a failure of the blower 7, but the present invention is not limited to this. It may also be applied to detection. That is, if the detected temperature S indicates a temperature too high to be detected in normal combustion in the combustor, it is determined that the sensor 25 is short-circuited, and conversely, if the detected temperature S indicates a temperature too high to be detected in normal combustion, it is determined that the sensor 25 is short-circuited. If it shows an abnormally low value that cannot be detected, it is determined that the sensor 25 is disconnected. Even when these abnormalities occur, the entire control device may be put into a non-returning stopped state and the indicator 30 may be used to warn the occupant, as in the previous embodiment. In particular, by changing the blinking pattern of the indicator 30, the cause of the abnormality can be determined.

In addition, in the above-mentioned embodiment, the abnormality of the heating air blower was described as the abnormality of the combustion type heater.
The present invention is not limited to this, and the present invention can also be applied, for example, when a fuel pump or a combustion air supply blower malfunctions and excessive fuel or air is supplied to the combustion chamber, causing the heat exchanger temperature to rise abnormally.

(Effects of the Invention) As described above, combustion 1 of the combustion type heater for a vehicle according to the present invention
When the heat exchanger temperature detected by the temperature sensor is higher than the first predetermined temperature, the 1i1J control device determines that the heat exchanger is in an overheating state, stops the fuel supply to the combustor, and stops the heat exchanger. When the detected temperature of the heater exceeds a second predetermined temperature which is higher than the first predetermined temperature, it is determined that there is an abnormality in the combustion type heater and the operation of the combustion type heater is stopped. It is possible to distinguish between minor or temporary abnormalities and fatal abnormalities in combustion heaters using a low-cost and simple method, and to prevent their recurrence, thereby preventing wasteful consumption of fuel and overheating. safety can be ensured.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the operation of this control device, FIG. 2 is a combustion control device for a combustion type heater for a vehicle, and FIG. 3 is a diagram showing a control state when the blower 7 is in a substantially normal state. , the same figure (a) is a figure showing the time change of the temperature TIN in the storage arKt5, the same figure (b) is a figure showing the time change of the heat exchanger temperature, the same figure (c) is a figure showing the fuel supply amount and the flow of the blower 7. A waveform diagram showing the operation of the air volume. Fig. 4 is a diagram showing the control state when the air volume of the blower 7 has decreased somewhat. Fig. 5 is a waveform diagram showing the control state when the air volume of the blower 7 is lower than that shown in Fig. 4. Fig. 6 is a diagram showing the control state when the air flow rate of the blower 7 becomes almost completely zero, and Fig. fJS7 is a flowchart of the program showing the operation by the microcomputer 20. - Combustor, 2... Heat exchanger, 4...-Control unit, 7... Heating air blower (blower means),
20... Microcomputer, 25... Temperature sensor, 30... Indicator, Tb... Predetermined temperature (first predetermined temperature), Ta... Predetermined temperature (second predetermined temperature).

Claims (1)

[Claims] 1. A combustor, a heat exchanger provided around the combustor, a temperature sensor for detecting the temperature of the heat exchanger, a blower means for introducing air into the heat exchanger, and a heat exchanger provided around the combustor. A combustion control device for a combustion type heater for a vehicle comprising a fuel supply means for supplying fuel, the combustion control device controlling the amount of fuel supplied by the fuel supply means and the amount of air blown by the blower means, When the heat exchanger temperature detected by the temperature sensor is higher than the first predetermined temperature, it is determined that the heat exchanger is in an overheating state, and the fuel supply to the combustor is stopped. For a vehicle, when the detected temperature exceeds a second predetermined temperature higher than the first predetermined temperature, it is determined that there is an abnormality in the combustion type heater and the operation of the combustion type heater is stopped. Combustion control device for combustion type heaters.