JPH0478611A - Control device of combustion type heater - Google Patents

Abstract

PURPOSE:To always certainly ignite a combustion type heater and continue combustion by detecting temperature of flame generated at the time of combus tion of an air-fuel mixture and changing a fuel pump and an air blower from medium output over to the maximum output at the time when the detected flame temperature reaches a set temperature. CONSTITUTION:A control device 20 has a control part 30, a memory 31 and a timer 32, and a manual switch 24 and a flame sensor 21 are connected to the input side of the control part 30 and a glow plug 7, a fuel pump 2 and a blower 4 are connected to the output side of the control part 30 respectively. Among them, a flame temperature detection means is constituted of the flame sensor 21 and an output change-over means is constituted of the control part 30 and the memory 31 respectively. Then, the control part 30 computes and processes each kind of input signals and outputs a signal to actuate the glow plug 7, the fuel pump 2 and the air blower 4. At this time, the growth state of flame is sensed by way of detecting a flame temperature and when the flame grows to a certain degrees (when the flame temperature is about 200 deg.C), each output of the fuel pump 2 and the air blower 4 is changed from a half state over to a full state.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a control device for a combustion type heater, and in particular, to a control device for a combustion type heater, which can always be reliably controlled regardless of changes in the characteristics of component parts or fluctuations in outside temperature. The present invention relates to a control device for a combustion heater that can be ignited.

(Prior Art) Engine cooling water, which has been heated to a high temperature by cooling the engine, is normally used as a heat source for heating the interior of a vehicle. However, for example, in vehicles such as buses and one-box cars, which have a relatively large interior volume and require a large amount of heat for heating, using engine cooling water as the only heat source may not provide enough heat. A combustion type heater, which forcibly heats engine cooling water by burning gasoline, kerosene, light oil, etc., is used as an auxiliary heat source. Such a combustion type heater was developed in U.S. Pat.
This method is disclosed in Japanese Patent No. 128506 and the like.

FIG. 4 shows an example of a conventional combustion type heater 1. This combustion type heater 1 is connected in series to a heater core of an automobile air conditioner (not shown) in an engine cooling system, for example. It functions to heat the cooling water flowing into the heater core.

This combustion type heater 1 mixes vaporized fuel supplied from a fuel tank (not shown) to a vaporization mat 3 by a fuel pump 2 and combustion air supplied from an air intake port 5 by a blower 4 in a combustion chamber 6. This air-fuel mixture is ignited by a glow plug 7 and is continuously combusted within the combustion chamber 6. In this way, high temperature combustion gas is generated within the combustion chamber 6. Note that a flame is generated within the combustion chamber 6 when the air-fuel mixture is combusted.

The combustion gas generated in the combustion chamber 6 is reversed at the tip of the combustion tube 8, passes between the outer peripheral wall of the combustion tube 8 and the inner peripheral wall of the heat transfer tube 9, and is discharged to the outside from the exhaust port 10.

On the other hand, the engine cooling water heated by the combustion heater 1 is supplied to the hot water inlet (engine side) by the water pump 11.
12 to a passage 14 between the inner circumferential wall of the outer cylinder 13 and the outer circumferential wall of the heat transfer tube 9, and is heated by heat exchange with the high temperature combustion gas via the heat transfer tube 9, and the hot water exit ( The air is guided from the heater core side) 15 into a heater core (not shown), and heats the air blown into the vehicle interior by heat exchange with the air passing through the heater core. Thereby, the interior of the vehicle can be sufficiently heated.

The combustion heater 1 also includes a flame sensor 21 that detects the temperature inside the combustion chamber 6, a water temperature sensor 22 that detects the temperature of cooling water, and an overheat sensor 23 that detects the surface temperature of the heat transfer tube 9. are arranged at predetermined positions, respectively, and various information from these sensors 21 to 23 is input to a control device 20 that controls the combustion heater 1 .

Then, when the manual switch 24@<< is turned on to start the operation of the combustion type heater 1, the control device 20, based on the information from the various sensors 21 to 23, for example, according to the timing shown in FIG. Controls the fuel pump 2, blower 4, glow plug 7 and water pump 11,
Combustion is controlled so that the temperature of the engine cooling water heated by the combustion heater 1 falls within a predetermined temperature range.

Among the controls by the control device 20, the control at the time of ignition (ignition sequence) is as shown in the timing chart of FIG.
When N is turned on, the blower 4 is first operated at full power for about 5 seconds to scavenge air, and then the glow plug 7 is turned on for about 30 seconds to preheat its surface to the temperature required for ignition. , the vaporizing mat 3 is preheated by the residual heat (glow preheating).

After the glow preheating is completed, the control device 20 first operates the fuel pump 2 at full power, which is the maximum output, for about 5 seconds to supply the fuel vaporized by the vaporization mat 3 into the combustion chamber 6. Thereafter, in order to ensure ignition, the output of the fuel pump 2 is temporarily reduced to an intermediate output, which is a half state, and at the same time, the blower 4 is operated at an intermediate output, which is a half state, to supply combustion air into the combustion chamber 6. As a result, the air-fuel mixture in the combustion chamber 6 is ignited, and combustion begins. In order to ensure that this combustion continues, approximately 3 seconds after the fuel pump 2 and the blower 4 enter the half state, the fuel pump 2 and the blower 4
Switch each output to full state at the same time.

After that, the combustion chamber 6 detected by the flame sensor 21
The temperature inside rises above a specified temperature and ignites (or burns)
When confirmed, the control device 20 turns the glow plug 7 to O.
FF.

In addition, in order to deal with the so-called ignition error in which the ignition is not ignited even after a predetermined period of time has elapsed during startup, the conventional control device 20 has a glow that automatically restarts the ignition operation when an ignition error is detected. Some are designed to control the plug 7, the fuel pump 2, and the blower 4.

(Problem to be Solved by the Invention) However, in such a conventional control device 20, each control of the fuel pump 2 and the blower 4 is simply time control based on a timer. The rate of ignition at one time during startup (ignition rate) is affected by changes in characteristics due to durability deterioration of the air blower 4, fluctuations in outside temperature, etc.
There is a risk that this may decline. Furthermore, if the ignition becomes unstable in this way, problems such as white smoke coming out of the exhaust port 10 may occur, which may cause discomfort to the user.

That is, as mentioned above, when igniting, first set the fuel pump 2 and blower 4 to the half state to ensure ignition once, and then switch the fuel pump 2 and the blower 4 to the full state when the flame has grown to a certain extent. Although combustion is ensured to continue, the timing of switching the fuel pump 2 and blower 4 from half to full state must not be too early or too late in relation to the flame growth state (too early may cause the flame to (If it is too late, the flame tends to recede due to lack of air, so there is not enough spark, and the fire ends up extinguishing.) In this regard, conventionally, as mentioned above, a predetermined period of time (3 seconds) after the fuel pump 2 and the blower 4 are in the half state is used.
When the time period passed, their outputs were automatically switched to full state.

However, as the fuel pump 2 and the blower 4 deteriorate in durability, the startup speed of the fuel supply teeth and the fan change, so even if the control device 2
Even if a signal is received from the controller, it is not always possible to transition to the full state at the appropriate timing. Furthermore, since the growth rate of the flame changes depending on the outside temperature, even if changes in the characteristics of the fuel pump 2 or the blower 4 can be ignored, the timing may not always be appropriate. In any case, if the switching timing is lost, an ignition error will occur. And if an ignition error occurs,
Incomplete combustion gas will be exhausted from the exhaust port 10.

The present invention has been made in order to solve the problems of the prior art described above, and is a combustion type that can always reliably ignite regardless of changes in characteristics due to durability deterioration of the fuel pump or blower, fluctuations in outside temperature, etc. An object of the present invention is to provide a heater control device.

[Structure of the Invention] (Means for Solving the Problems) The present invention for achieving the above-mentioned object mixes fuel supplied by a fuel pump and air supplied by a blower in a combustion chamber, and generates this mixture. ignited by a glow plug and continuously combusted in the combustion chamber, the control device includes a flame temperature detection means for detecting the temperature of a flame generated when the air-fuel mixture is combusted; The present invention is characterized by comprising an output switching means for switching the fuel pump and the blower from an intermediate output to a maximum output when the detected flame temperature reaches a set temperature.

(Function) The combustion type heater control device configured as described above functions as follows.

When the flame temperature detected by the flame temperature detection means reaches a set temperature, the output switching means determines that the flame has grown to some extent and switches the fuel pump and blower from intermediate output to maximum output, respectively.

As a result, the combustion type heater is always reliably ignited and continues to burn, regardless of changes in characteristics due to deterioration of the fuel pump or blower or fluctuations in outside temperature.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic configuration diagram of a control device for a combustion type heater according to an embodiment of the present invention, and the same members as those shown in FIG. 4 are given the same reference numerals.

Note that the configuration of the combustion type heater is the same as the conventional one shown in FIG. 4, so a description thereof will be omitted.

As shown in FIG. 1, the control device of the present invention includes a control section 30
, a memory 31 and a timer 32, and the control unit 30 includes:
A manual switch 24 and a frame sensor 21 are connected to the input side, and a glow plug 7, fuel pump 2, and blower 4 are connected to the output side. Among these, frame sensor 2
1 forms a flame temperature detection means, and the control section 3
0 and the memory 31 form an output switching means.

Note that the control unit 30, memory 31, and timer 32 are provided in the control device 20 shown in FIG. 4 described above.

The control unit 30 processes various human power signals and outputs signals for operating the glow plug 7, fuel pump 2, and blower 4 to these. In this embodiment, the control unit 30 performs the same control as conventionally for the combustion type heater 1, except for output switching control of the fuel pump 2 and the blower 4 at the time of ignition, which will be described later.

The memory 31 stores in advance a flame temperature (for example, 200° C.) as a set temperature, which realizes an appropriate timing for switching the fuel pump 2 and the blower 4 from a half state, which is an intermediate output, to a full state, which is a maximum output. There is.

As mentioned above, in order to ensure ignition, the stage when the flame has grown to a certain extent (in terms of flame temperature, approximately 2009
It is preferable to switch the fuel pump 2 and the blower 4 to the full state at a temperature of 400 to 500 degrees Celsius), and in this embodiment, the possibility of a start-up delay due to deterioration of the durability of the fuel pump 2 and the blower 4 is taken into consideration. , set the switching timing to the lower flame temperature of 200°C.

Moreover, the timer 32 is for measuring the time required for the control unit 30 to perform time control.

As mentioned above, the flame sensor 21 is conventionally used to detect the temperature inside the combustion chamber 6 as a means for confirming ignition, but in this embodiment, it is used to detect the temperature inside the combustion chamber 6. It is also used as a detection means and to detect the temperature of the flame generated during combustion. Of course, another flame sensor may be placed at an appropriate location to detect the flame temperature as accurately as possible. Further, the sensor for detecting the flame temperature may be a thermocouple as well as a temperature measuring resistor such as a flame sensor, and any suitable sensor may be selected.

FIG. 2 is a timing chart at the time of ignition of the control device configured as described above.

As shown in Fig. 2, this control device temporarily sets the outputs of the fuel pump 2 and the blower 4 to half state approximately 40 seconds after startup, and then when the flame temperature reaches 200°C, the output of the fuel pump 2 and the blower 4 are set to half. Control is performed to switch each output of the blower 4 to the maximum output, full state. Control other than this is completely the same as conventional control (see FIG. 5).

FIG. 3 is a flowchart of the operation of the present control device including such control during ignition, and illustrates the case where the above-described ignition error prevention system is applied.

First, the control unit 30 determines whether the manual switch 24 is turned on (Sl), and as a result, the manual switch 24 is turned on.
If 4 is ON, 1 is assigned to the counter n in the memory 31 to remember that this is the first ignition operation (
At the same time, the blower 4 is operated at full capacity for scavenging air ($3).

Then, the control unit 30 waits until a predetermined scavenging time (for example, 5 seconds) has elapsed. When the scavenging time has elapsed, the control unit 30 stops the operation of the blower 4 and starts the glow plug 7 to perform glow preheating. Power is supplied to heat it ($5).

Then, the control unit 30 controls the preheating time (for example, about 3
When the preheating time has elapsed, first, only the fuel pump 2 is operated at full power for about 5 seconds (S7), and then the output of the fuel pump 2 is reduced to half state. At the same time, the blower 4 is operated in half mode ($8) to start combustion.

Then, the control unit 30 inputs the flame temperature detected by the flame sensor 21 ($9), and detects the growth state of the flame by determining whether this flame temperature is, for example, 200° C. or higher (S10). . As a result, if the flame temperature has not reached 200℃, it will return to $8 and increase to 2
The control unit 30 waits until the temperature reaches 00°C, and when the flame temperature reaches 200°C, outputs a signal to the fuel pump 2 and the blower 4 to switch their respective outputs to the full state (
S11). This ensures that the combustion grows and continues.

Then, the control unit 30 inputs the combustion chamber temperature from the flame sensor 21, and determines that this temperature corresponds to a combustion start state in which combustion has started within a predetermined time (for example, about 90 seconds after starting the fuel pump 2). The presence or absence of ignition is confirmed by determining whether the temperature has reached a predetermined temperature or higher (S12.
813).

When the control unit 30 confirms ignition, it stops power supply to the claw plug 7, resets the counter n, shifts to normal heating control mode, and starts combustion so that the water temperature falls within a predetermined temperature range. control (S14).

On the other hand, if the control unit 30 determines that ignition has not occurred in S12 and S13, it stops the operation of the fuel pump 2 ('515) in preparation for the ignition operation again, and scavenges the inside of the combustion chamber 6. After the predetermined scavenging time required for this has elapsed, the operation of the blower 4 is stopped (S16.517).

Then, the control unit 30 increments the value of the counter n in the memory 31 by 1 to memorize that an ignition error has occurred (S18), and if the value of the counter n is 2 or less, the process returns to S5 to try again. Perform ignition operation (S19)
. However, when the value of this counter n becomes 3, that is,
If ignition does not occur even after the above two ignition operations, all operations are terminated.

Therefore, according to this embodiment, the growth state of the flame is detected by detecting the flame temperature, and when the flame has grown to a certain extent (when the flame temperature is approximately 200°C), the outputs of the fuel pump 2 and the blower 4 are detected. Since the outputs of the fuel pump 2 and blower 4 are switched from half to full, the outputs of the fuel pump 2 and blower 4 are always adjusted at the appropriate timing, regardless of changes in characteristics due to durability deterioration of the fuel pump 2 and blower 4, fluctuations in outside temperature, etc. As a result, the combustion heater 1 can be reliably ignited. Therefore, the ignition reliability is improved.

Furthermore, according to this embodiment, the flame sensor 21, which was conventionally provided, is substituted as a sensor for detecting the temperature of the flame, so there is no need to make any changes to the conventional device configuration, simply changing the program. There is almost no cost increase. Even if a separate sensor for flame temperature detection is provided, the cost increase will be kept to a minimum since there is no change in the other device configurations.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, it is possible to always reliably ignite the combustion type heater regardless of changes in characteristics due to durability deterioration of the fuel pump or blower, fluctuations in outside temperature, etc. This makes it possible to improve ignition reliability.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a control device for a combustion type heater according to an embodiment of the present invention, FIG. 2 is a timing chart of the control device shown in FIG. 1 during ignition, and FIG. 3 is a diagram similar to the one shown in FIG. FIG. 4 is a schematic configuration diagram of a conventional combustion heater, and FIG. 5 is a timing chart of the control device shown in FIG. 4. 21...Flame sensor (flame temperature detection means), 30
...Control unit (output switching means), 31...Memory (output switching means), 32...Timer.

Claims (1)

[Claims] Fuel supplied by fuel pump (2) and blower (4)
) in the combustion chamber (6),
A combustion type heater (
In the control device of 1), flame temperature detection means (21) detects the temperature of a flame generated when the air-fuel mixture is combusted;
When the flame temperature detected by the flame temperature detection means (21) reaches the set temperature, output switching means (30, 31) switches the fuel pump (2) and the blower (4) from intermediate output to maximum output. A control device for a combustion type heater, comprising: