JPH02150615A - Controlling apparatus of combustion of combustion-type heater for vehicle - Google Patents

Abstract

PURPOSE:To make it possible to obtain an optimum state of combustion invariably even when a supply voltage varies by storing beforehand a duty ratio map on a change in a duty ratio in accordance with a change in the supply voltage, by determining the duty ratio from the amount of supply of a liquid fuel and the supply voltage and by controlling a combustion air supply blower on the basis of the duty ratio. CONSTITUTION:Duty ratio maps A1 and A2 on a change in a duty ratio in accordance with a change in a supply voltage (voltage of a battery 24 of a vehicle) are stored beforehand in a memory element, with respect to the minimum amount of supply of fuel and the maximum amount of supply of fuel by a fuel pump 11. A microcomputer 20 selects the duty ratio map A1 when the amount of supply of fuel by the fuel pump 11 is minimum, and determines the duty ratio on the basis of the map, while selecting the duty ratio map A2 when the amount of supply of fuel is maximum and determining the duty ratio on the basis of this map. A combustion air supply blower 15 is controlled on the basis of the duty ratio thus determined.

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 that heats a vehicle interior, a heat storage compartment of a heated vehicle, etc. The present invention relates to a combustion control device for a combustion heater for a vehicle that can control the supply amount.

(Prior Art) Conventionally, such a combustion control device for a combustion type heater for a vehicle has been provided with a control means that changes the air volume of a combustion blower in multiple stages or steplessly in response to changes in the amount of fuel supplied, for example. There is a device in which the amount of combustion air supplied can be adjusted so that combustion is always performed within the optimum combustion range even if the amount of fuel supplied changes (Japanese Patent Laid-Open No. 169421/1983).

(Problems to be Solved by the Invention) However, in the above-mentioned conventional technology, the supply amount of combustion air is adjusted by controlling the voltage of the motor of the combustion blower. That is, by changing the voltage value applied to the combustion blower motor in multiple stages using a resistor or steplessly using a transistor, the rotational speed of the motor can be changed to change the amount of air blown by the combustion blower. It consists of Therefore, in the prior art described in 1., the vehicle battery voltage (
Due to changes in the power supply voltage), the voltage value applied to the combustion blower motor changes and the amount of combustion air supplied changes. The problem is that it becomes impossible to obtain This problem can be solved by voltage feedback control when the voltage value applied to the combustion blower motor is changed steplessly using a transistor, but this requires a voltage feedback circuit. However, there is a problem that the circuit configuration becomes complicated.

The present invention has been made by focusing on these conventional problems, and it is possible to control the supply amount of combustion air so that the optimum combustion condition is always obtained even if the power supply voltage changes, and
It is an object of the present invention to provide a combustion control device for a combustion type heater for a vehicle, which has a simplified circuit configuration by eliminating the need for a feedback circuit for power supply voltage correction.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a combustion type heater for a vehicle that burns a mixture of liquid fuel and combustion air, and in which the liquid fuel is supplied by a fuel pump. In a combustion control device for a combustion type heater for a vehicle that can control the supply amount of combustion air by a combustion air supply blower, the duty ratio is adjusted according to a change in the power supply voltage for the supply amount of each liquid fuel that can be controlled. The combustion air supply blower is provided with a control means that stores in advance a duty ratio map in which the fuel consumption changes, determines the duty ratio from the supply amount of liquid fuel and the power supply voltage, and controls the combustion air supply blower using this duty ratio. be.

(Function) And, in the above-mentioned combustion control device for a combustion type heater for a vehicle,
The control means selects a duty ratio map corresponding to the current supply amount of liquid fuel, determines a duty ratio from the current power supply voltage based on this map, and controls the combustion air supply blower with this duty ratio. do.

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

FIG. 1 schematically shows the entire combustion control device for a combustion type heater for a vehicle according to an embodiment. 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 is a combustion heater unit that includes a combustor 1 and a heat exchanger 2 that combust a mixture of vaporized liquid fuel and combustion air to generate high-temperature combustion gas. 3, and a control unit 4 that controls combustion of the heater unit 3.

In the combustion type heater unit 3, heating air is introduced into the duct 6 from the inside of the warming storage 5 of the heating delivery vehicle through the inlet 6a, and the inside of the duct 6 is introduced into the air outlet 6b into the heating storage 5. A heating air blower 7 is provided to blow air toward the room.

The heating air from inside the heat storage 5 is blown through the duct 6 toward the outlet 6b by the blower 7, while being heat exchanged with the high temperature combustion gas introduced from the combustor 1 by the heat exchanger 2. It is designed to be heated.

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
0 liquid fuel is supplied through a pipe 12 by a fuel pump 11. This fuel pump 11 is a fuel pump 11
By changing the frequency of the pulse signal that controls the drive motor of the motor and changing the rotational speed of the motor, an OFF position where fuel supply is stopped, an LO position where the minimum amount of fuel supply is obtained, and a maximum amount of fuel supply are determined. can be controlled in three stages of 11 positions. Note that the amount of fuel supplied by the fuel pump 11 can also be configured to be switchable in multiple stages or steplessly. The combustion tube 8 includes a glow plug 13 that vaporizes the liquid fuel impregnated in the short wick 9 and ignites and burns a mixture of the vaporized liquid fuel and combustion air, and an ignition sensor 14 that detects ignition. and is provided.

Combustion air is supplied to the piping 1 by a 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 amount of combustion air supplied is determined by the combustion air supply blower 15.
The amount of air blown is controlled by controlling the duty ratio using the method described below.

The control unit 4 includes a microcomputer 20,
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.

A portion of this memory contains a duty ratio map A1. A2 (see FIG. 2) is stored in advance.

The multiplexer 21 is connected to a voltage signal of the battery 24 divided by resistors R1 and R2 in order to detect the power supply voltage V, and to detect the temperature of the heating air introduced into the duct 6 from the heat storage compartment 5. 5, an ignition signal from the ignition sensor 14, and an ignition signal from the ignition sensor 14 to prevent the heat exchanger 2 from overheating. Heat exchanger temperature signals from several heat exchanger temperature sensors 26 placed on the outer surface of the heat exchanger 2 are respectively input. Each signal input to the multiplexer 21 is sequentially supplied to the input section of the microcomputer 20 via the A/D converter 22.

Output signals from each output section of the microcomputer 20 are output to the drive elements 27 to 30 and a temperature display 31 that displays the temperature inside the heat-insulating warehouse 5, respectively.

The drive element 27 controls the rotational speed of the drive motor of the fuel pump 11 by applying a pulse signal having a frequency corresponding to the output signal from the microcomputer 20 to the drive motor of the fuel pump 11, thereby increasing the amount of fuel supplied by the fuel pump 11 to the three levels. It is configured so that it can be controlled in stages. Here, the amount of fuel supplied by the fuel pump 11 becomes the maximum fuel supply amount HI at the time of startup, and becomes the minimum amount when the internal temperature inside the insulated warehouse 5 detected by the internal temperature sensor 25 exceeds a predetermined upper limit value. The fuel supply amount is LO, and when the temperature inside the refrigerator falls below a predetermined lower limit value, the fuel supply amount is controlled to be the maximum fuel supply amount HI again.

The drive element 28 is configured to apply a predetermined voltage to the glow plug 13 to ignite it in response to an output signal from the microcomputer 20 upon startup.

The drive element 29 supplies combustion air with a pulse signal S as shown in FIG. It is configured to output to the motor of the blower 15. In the blower 15, a transistor (not shown) is turned on only while the pulse signal S is on, and the motor thereof is driven. Therefore, as the duty ratio of the pulse signal S increases, the rotational speed of the motor increases, and as a result, the amount of combustion air supplied by the blower 15 increases.

Here, when the fuel supply amount by the fuel pump 11 is the minimum fuel supply amount LO, the microcomputer 20 selects the duty ratio map At from the duty ratio maps At and A2, and also selects the duty ratio map At from the duty ratio maps At and A2.
The duty ratio is determined from the current power supply voltage based on the current power supply voltage, and when the fuel supply amount is the maximum fuel supply amount HI, the duty ratio map A2 is selected and the duty ratio number is determined from the current power supply voltage based on this map A2. Then, the combustion air supply blower 15 is controlled using this duty ratio. For example, when duty ratio map A1 is selected, the duty ratio is approximately 40% when the power supply voltage is 25V, and when duty ratio map A2 is selected, the duty ratio is approximately 40% when the power supply voltage is 25V.
When the voltage is V, the duty ratio is approximately 60% (see FIG. 2). What is important here is that the combustion air supply blower 15 is controlled by the duty ratio determined by the microcomputer 20 as described above, so that the power supply voltage 2
4 is corrected, and the fuel supply amount (L
This means that the optimum amount of combustion air for O or HI) is supplied into the combustion chamber 8a, so that optimum combustion conditions are always obtained.

Furthermore, the microcomputer 20 controls the amount of fuel supplied when it decreases from the maximum fuel supply amount HI to the minimum fuel supply amount LO (time L1 in FIG. 5) and conversely when it increases (
At the time L2 in FIG. 5), the following calculation is performed so as to linearly change the duty ratio within two constant times T.

D=D2+ (DI-D2)X (1--t)/T where Dl is the duty ratio before the fuel supply amount changes, D
2 is the duty ratio after the change (However, when the fuel supply amount increases as shown at 2 in Fig. 5, the duty ratio before the fuel supply amount changes is D2, and the duty ratio after the change is D2. is Dl), T is the linear control time, and T is the time from the start of the linear control.

The reason for performing such linear control is as follows.

Since the short core 9 is temporarily impregnated with the fuel supplied from the fuel pump 11, when the amount of fuel supplied by the fuel pump 11 changes, the combustion state within the combustion chamber 8a does not grow after a certain time delay from the time of the change. (if the fuel supply increases) or decreases (if the fuel supply decreases). Therefore, in order to always ensure optimal combustion conditions even when the amount of fuel supplied changes, it is necessary to Preferably, the amount is gradually increased or decreased in accordance with said time delay after the fuel supply changes. In order to increase/decrease the amount of combustion air supplied in this way, the duty ratio is linearly changed within two fixed time periods T.

For example, like the drive element 27, the drive element 30 controls the rotational speed of the motor 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 supply blower 7. By doing so, the amount of heating air blown by the blower 7 can be switched and controlled in multiple stages.

The operation will be explained below with reference to FIG.

First, when a switch (not shown) is turned on to start up the apparatus, it is determined in step 401 whether or not a linear control flag is set. Since the linear control flag is not set at the time of startup, the answer to step 401 is negative (No), and the process proceeds to the next step 402, where it is determined whether or not the fuel supply amount has changed. At startup, the normal fuel supply amount is maintained at the maximum supply amount HI, so the answer to step 402 is negative (No), and the next step 403
Proceed to ゜404. Since the fuel supply amount by the fuel pump 11 is the maximum fuel supply amount HI at this time, the microcomputer 20 selects the duty ratio map A2 from the duty ratio maps AI and A2 (step 403), and also selects the duty ratio map A2 from the duty ratio maps AI and A2. The duty ratio is determined from the current power supply voltage based on A2 (step 404). At this determined duty ratio, the combustion air supply blower 15
is driven (step 4o5). As a result, the amount of combustion air supplied by the combustion air supply blower 15 is controlled to the optimum amount for the fuel supply amount at that time while correcting fluctuations in the power supply voltage, and as a result, the optimum combustion state is always maintained. is obtained.

Such steps 401 to 405 are repeated from startup until 1 o'clock as shown in FIG. 5.

When the fuel supply amount decreases from the maximum fuel supply amount I-II I to the minimum fuel supply amount LO (times t and x in FIG. 5), the answer to step 402 becomes affirmative (Yes), and the process proceeds to step 406. Set the linear control flag with . After this setting, the timer is set to two fixed times T (step 407) and the duty ratio D1 immediately before the change in fuel supply amount is maintained (step 408).
1, the combustion air supply blower 15 is driven (step 405).

Since the linear control flag is set in step 406, the answer to step 401 becomes affirmative (Yes), and the process proceeds to steps 409 and 410. The microcomputer 20 determines the duty ratios DI and D2 before and after the change in the fuel supply amount in step 409, and calculates the duty ratios based on the above formula in step 410. The combustion air supply blower 15 is driven with this calculated duty ratio (step 411), and the timer is subtracted (step 412), and the timer is set to 1.
It is determined in step 413 whether or not the fixed time T has elapsed, and until the fixed time T has elapsed, the answer to step 413 is negative (No) and steps 401, 409 to 413 are performed.
is repeated. When a certain period of time T has elapsed, step 41
The answer to step 3 is affirmative (Yes), and the process advances to step 414 to clear the linear control flag.

In this way, from time t1 when the fuel supply amount decreases from the maximum fuel supply amount HI to the minimum fuel supply amount LO until time t1' when one fixed time T has elapsed, the duty cycle for driving the combustion air supply blower 15 is The ratio decreases linearly.

Since the linear control flag is cleared in step 414, the answer to step 401 becomes negative (No) again, and steps 401 to 405 are repeated until L2. At this time, since the fuel supply amount by the fuel pump 11 is the minimum fuel supply amount LO, the microcomputer 20 selects the duty ratio map A1 from the duty ratio maps AI and A2 (step 403).
At the same time, the duty ratio is determined from the current power supply voltage based on this map A1 (step 404).

When the fuel supply amount increases from the minimum fuel supply amount LO to the maximum fuel supply amount HI (at 2 o'clock in FIG. 5), the answer to step 402 becomes affirmative again (Yes), and step 40
At step 6, the linear control flag is set again, and at step 407, the timer is set again to one fixed time T.

Steps 401.409 to 414 are then executed again as described above, whereby the fuel supply amount increases from the minimum fuel supply amount T,O to the maximum fuel supply 1tlI, and from 2 o'clock the 1 fixed time T is increased. Until time t2' elapses,
The duty ratio for driving the combustion air supply blower 15 increases linearly.

Since the linear control flag is cleared again in step 414, the answer to step 401 becomes negative (No) again, and steps 401 to 405 are repeated again. At this time, since the fuel supply amount by the fuel pump 11 is the maximum fuel supply amount HI, the microcomputer 20 selects the duty ratio map A2 from the duty ratio maps AI and A2 (step 403). The duty ratio is determined from the current power supply voltage based on map A2 (step 404).

(Effects of the Invention) As detailed above, according to the combustion control device for a combustion type heater for a vehicle according to the present invention, the combustion type heater for a vehicle burns a mixture of liquid fuel and combustion air. , a combustion control device for a combustion heater for a vehicle that can control the amount of liquid fuel supplied by a fuel pump and the amount of combustion air supplied by a combustion air supply blower, in which the supply amount of each liquid fuel that can be controlled is controlled by a power source. A duty ratio map in which the duty ratio changes according to changes in voltage is stored in advance, and a duty ratio is determined from the supply amount of liquid fuel and the power supply voltage, and the combustion air supply blower is controlled using this duty ratio. The configuration includes a control means that selects a duty ratio map corresponding to the current supply amount of liquid fuel, determines a duty ratio from the current power supply voltage based on this map, and uses this duty ratio for combustion. Controls the air supply blower. Therefore, fluctuations in the power supply voltage 24 are corrected, and the optimum amount of combustion air is supplied for the amount of fuel supplied at that time, so that an optimum combustion state can always be obtained. Moreover, since a feedback circuit for power supply voltage correction is not required, the circuit configuration can be simplified.

[Brief explanation of the drawing]

1 to 5 show one embodiment of the present invention, and FIG. 1 is a schematic diagram showing the entire combustion control device for a combustion type heater for a vehicle;
Figure 2 is a graph showing the duty ratio map stored in the microcomputer, Figure 3 is a diagram showing the pulse signal that drives the combustion air supply blower, Figure 4 is a flowchart showing the operation, and Figure 5 is the fuel amount. FIG. 2 is an explanatory diagram showing the relationship between and duty ratio. DESCRIPTION OF SYMBOLS 11... Fuel pump, 15... Combustion air supply blower, 20... Microcomputer (control means), 2
4...Power supply, At, A2...Duty ratio map.

Claims (1)

[Claims] 1. A combustion heater for a vehicle that burns a mixture of liquid fuel and combustion air, which can control the amount of liquid fuel supplied by a fuel pump and the amount of combustion air supplied by a combustion air supply blower. In the combustion control device for a combustion type heater, regarding the supply amount of each liquid fuel that can be controlled,
A duty ratio map in which the duty ratio changes according to changes in the power supply voltage is stored in advance, and the duty ratio is determined from the supply amount of liquid fuel and the power supply voltage, and the combustion air supply blower is operated at this duty ratio. A combustion control device for a combustion type heater for a vehicle, characterized in that a control means for controlling the combustion type heater is provided.