JP3419961B2 - Combustion heater - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a combustion type heater.

[0002]

2. Description of the Related Art As a vehicle indoor heating, a method of supplying engine cooling water to a heat exchanger provided in a room and exchanging heat with indoor air in the heat exchanger is generally used. A combustion type heater that burns a part of the fuel of the engine as an auxiliary heater until the temperature of the cooling water of the engine rises sufficiently to heat the indoor air directly or the circulating water to the heat exchanger provided in the room. Is used.

FIG. 8 shows an example of the above combustion type heater, in which a burner 92 for performing combustion is arranged in a housing 91, and an exhaust port 911 is provided in a wall of the housing 91. A circulating water flow passage 931 is formed in the wall of the housing 91 surrounding the burner 92. The circulating water flow passage 931, the water pump 932, and the heat exchanger 933 provided in the vehicle compartment are connected to each other by a circulating water pipe 934, and
A circulating water circuit that transfers the combustion heat generated in the nozzle 92 to the heat exchanger 933 is formed. A blower 9 that sends the air that has exchanged heat with the heat exchanger 933 close to the heat exchanger 933 to the occupants of the vehicle.
35 are provided.

The burner 92 is composed of a combustion cylinder 921 in which a flame is formed and a mixing cylinder 922 communicating with the combustion cylinder 921. A vaporizing member 94 for vaporizing the supplied fuel is provided at the end of the mixing cylinder 922, and the opening of the fuel supply pipe 954 is in contact with the surface of the vaporizing member 94. Fuel supply pipe 954
Is connected to a fuel pump 952 provided in the fuel tank 951 via a cutoff valve 953 by a pipe 955. Vaporizing member 9
4, a glow plug 97 is provided in proximity to the No. 4, and the glow plug 97 is connected to a power source 99 for energizing the glow plug 97 via a control device 98. An air introduction hole 923 for introducing air mixed with vaporized fuel into the mixing cylinder 922 is formed on the peripheral wall of the mixing cylinder 922, and the mixing cylinder 922 and the housing 91 are formed.
The space between is an air supply path. The air supply path is connected to the air pump 96 via an air supply port 912 provided on the housing wall. The shutoff valve 953, the air pump 96, the glow plug 97, etc. are connected to the control device 98 for controlling them.

In the operation of the combustion type heater, first, the fuel pump 952 is operated to supply the fuel from the fuel tank 951 to the vaporizing member 94, and the fuel is spread over the entire vaporizing member 94. The power source 99 energizes the glow plug 97, and the glow plug 97 heats the vaporization member 94, whereby the vaporization member 94 is heated.
The vaporization of the fuel spread over the whole is promoted, and the vaporized fuel diffuses into the mixing cylinder 922. On the other hand, the air pump 96 operates to supply air into the mixing cylinder 922, and becomes a mixed gas of combustion air and fuel (hereinafter, simply referred to as mixed gas). The energized glow plug 97 ignites the mixed gas, and the flame spreads from the mixing cylinder 922 to the combustion cylinder 921.

The operation of the combustion type heater when it is stopped is shown in the flow chart of FIG. 9 and FIGS.
This will be described with reference to the time chart of (B). When the combustion stop command is input to the control device (step 401 in FIG. 9), the control device starts the counting of the timer for counting the exhaust time T for cooling the burner after the combustion is stopped (step 402 in FIG. 9). ), Close the shutoff valve (step 403 in FIG. 9)
The supply of fuel is stopped (FIG. 10 (A)). At the same time, the air pump capacity is maximized (step 404 in FIG. 9) to supply the maximum supply amount of air [FIG. 10 (B) (in the example in the figure, the supply amount of air is maximum immediately before the combustion stop command is input. It is constant before and after the command is input)], and the inside of the burner is cooled. When the timer counts T (step 405 in FIG. 9), the air pump is stopped (step 40 in FIG. 9).
6) The air supply is stopped (Fig. 10 (B)), and the combustion type heat
Operation stops.

[0007]

By the way, unvaporized fuel remains in the vaporization member after the combustion is stopped. Therefore, there is a problem that after the combustion type heater stops operating, residual fuel is vaporized and evaporative emission occurs in which the residual fuel is accumulated in the vehicle or the like through an exhaust gas pipe or the like. FIG. 10C shows the amount of evaporative emission, which is a combustion type heat
It can be confirmed that a lot of them have occurred after the operation of the data was stopped.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a combustion type heater which can reduce evaporative emission generated after the operation of the combustion type heater is stopped.

[0009]

As shown in FIG. 1, in the first construction of the combustion type heater of the present invention, the housing 1 provided with the fluid passage 31 through which the fluid to be heated flows is provided. A burner 2 that heats the fluid, vaporization members 41 and 42 that vaporize the fuel used for combustion in the burner 2, and a vaporization member 4
1 and 42 are provided with fuel supply means 5 for supplying fuel and air supply means 61 for supplying air mixed with vaporized fuel, and further vaporize the fuel remaining in the vaporization members 41, 42 after the combustion is stopped. A residual fuel vaporization promoting means 7 for promoting;
Forced exhaust means 6 for forcedly exhausting vaporized fuel, and a combustion stop
The fuel remaining on the vaporizing members 41 and 42 when stopped
And a residual fuel reducing means 8 for reducing fuel consumption.
The residual fuel reducing means 8 is connected to the fuel supply means 5 by
Pre-set fuel stop preparation time immediately before stopping the supply
The amount of fuel supplied by the fuel supply means 5 is
Less than the amount of fuel supplied before the fuel stop preparation time
Control means 8 for controlling the fuel supply means 5 so that
1 and the above fuel stop preparation time and the fuel supply stopped
Air supply means 61 during the time from the start to the end of combustion
Before the fuel stop preparation time is reached.
The air supply hand so that it is less than the air supply
And the air control means 82 for controlling the stage 61 (Claim 1).

In the second construction of the combustion type heater of the present invention,
The residual fuel vaporization promoting means 7 is replaced by the vaporization members 41, 4
Heating means 71 for heating the burner 2, combustion detecting means 72 for detecting the presence or absence of combustion in the burner 2, and combustion detecting means 7
2 detects that combustion has stopped, the above heating means 71
Exhaust for controlling the forced exhaust means 6 to supply air with the air supply means 61 and the air supply means 61 after combustion is stopped by a preset supply amount. And the control means 62 (claim 2).

[0011]

[0012]

In the third construction of the combustion type heater of the present invention,
The air control means 82 is set so that the amount of air supplied is constant during the time from when the fuel supply means 5 stops the fuel supply to when the combustion is stopped (claim 3 ).

In the fourth construction of the combustion type heater of the present invention,
The air control means 82 is set so that the amount of air supply monotonously decreases during the time from when the fuel supply means 5 stops supplying fuel to when combustion stops (claim 4 ).

[0015]

In the combustion type heater having the above-mentioned first construction, the residual fuel vaporization promoting means 7 promotes the vaporization of the fuel which remains in the vaporizing members 41 and 42 and is not vaporized when the combustion is stopped, and is vaporized. The residual fuel is forcibly exhausted by the forced exhaust means 6. As a result, the amount of residual fuel that causes evaporative emission is reduced, which can reduce the occurrence of evaporative emission after the operation of the combustion type heater is stopped. In addition, residual combustion
The fuel reduction means 8 keeps the fuel control means 8 during the fuel stop preparation time.
1 indicates that the amount of fuel supplied by the fuel supply means 5 is the above-mentioned fuel.
Fuel supply will be less than before the preparation time
The fuel supply means 5 is controlled as described above, and the air control means 82
However, the amount of air supplied by the air supply means 61 is
Less than the amount of air supply before the stoppage preparation time
The air supply means 61 is controlled as described above. This allows mixing
The proper air fuel ratio is maintained and vaporization
The amount of fuel spread to the members 41, 42 is reduced. Above fuel
When the stop preparation time elapses, the fuel supply means 5 supplies the fuel.
And the air supply means 61 continues to supply air.
It The supplied air and the amount of residual air remaining in the vaporizing members 41, 42
After a very weak combustion lasts for a short time due to the amount of fuel, the combustion stops.
Stop, and a small amount of non-vaporized fuel is vaporized by the vaporization members 41, 42.
Remains in. That is, when the combustion is stopped, the vaporization members 41, 4
2. Remaining fuel is reduced. A small amount of residual energy
The residual fuel vaporization promoting means 7
Amount of residual fuel that promotes and causes evaporative emission
Is further reduced. Forced exhaust means 6 for the vaporized residual fuel
Forcibly exhausts. As a result, the evaporation after the combustion is stopped
Emissions can be further reduced. In the combustion heater of the second configuration, when the combustion detection means 72 detects the stop of combustion, the heating control means 73 operates the heating means 71. The heating means 71 heats the vaporizing members 41 and 42, and thereby promotes vaporization of the fuel that remains in the vaporizing members 41 and 42 when combustion is stopped and is not vaporized. The exhaust control means 62 controls the air supply means 61 so as to supply a preset supply amount of air. The vaporized residual fuel is forcibly discharged by the air. Thus, the amount of residual fuel that causes evaporative emission is reduced. This can reduce the occurrence of evaporative emission after the combustion is stopped .

[0016]

In the third embodiment of the combustion type heater, during the fuel stop preparation time, the fuel control means 81 supplies the fuel supplied by the fuel supply means 5 with the amount of fuel supplied before the fuel stop preparation time. The fuel supply means 5 is controlled so as to be smaller than the supply quantity, and the air control means 82 supplies air so that the supply quantity of the air supplied by the air supply means 61 is smaller than the supply quantity before the fuel stop preparation time. Means 61
To control. This maintains an appropriate air-fuel ratio in the mixed gas and reduces the amount of fuel spread to the vaporizing members 41, 42. When the fuel stop preparation time has elapsed, the fuel supply means 5 stops the supply of fuel, and the air supply means 61 continues to supply air at a constant supply amount. Due to the supplied air and the small amount of fuel remaining in the vaporizing members 41, 42, extremely weak combustion continues for a short period of time and then the combustion stops, and a small amount of fuel remains in the vaporizing members 41, 42. The residual fuel vaporization promoting means 7 promotes the vaporization of the remaining small amount of non-vaporized fuel, and the amount of residual fuel that causes evaporative emission is further reduced. The forced exhaust means 6 forcedly exhausts the vaporized residual fuel. As a result, it is possible to further reduce the generation of evaporative emission after the combustion is stopped.

In the fourth embodiment of the combustion type heater, during the fuel stop preparation time, the fuel control means 81 supplies the fuel supplied by the fuel supply means 5 with the amount of fuel supplied before the fuel stop preparation time. The fuel supply means 5 is controlled so as to be smaller than the supply quantity, and the air control means 82 supplies air so that the supply quantity of the air supplied by the air supply means 61 is smaller than the supply quantity before the fuel stop preparation time. Means 61
To control. This maintains an appropriate air-fuel ratio in the mixed gas and reduces the amount of fuel spread to the vaporizing members 41, 42. When the fuel stop preparation time has elapsed, the fuel supply means 5 stops the supply of fuel, and the air supply means 61 continues to supply air. Very weak combustion continues due to the supplied air and a small amount of fuel remaining in the vaporizing members 41, 42, but the fuel remaining in the vaporizing members 41, 42 decreases with the above combustion, so the fuel vaporized from the vaporizing members 41, 42 The amount of will also decrease. By the control of the air control means 82, the supply amount of the air supplied by the air supply means 61 monotonously decreases, so that combustion is performed while maintaining an appropriate air fuel ratio. After the combustion continues for a short time, the combustion is stopped and a small amount of fuel remains in the vaporizing members 41 and 42. The residual fuel vaporization promoting means 7 promotes vaporization of a small amount of the remaining non-vaporized fuel,
The amount of residual fuel causing evaporative emission is further reduced. The forced exhaust means 6 forcedly exhausts the vaporized residual fuel. As a result, it is possible to further reduce the generation of evaporative emission after the combustion is stopped.

[0019]

【Example】

(Example 1) FIG. 1 shows a combustion type heater of the present invention. A burner 2 is disposed in the housing 1, and the burner 2 is a cylindrical combustion cylinder 21 having open both ends, and a mixing cylinder connected to the combustion cylinder 21 through a partition plate 28 having a hole. It is composed of a cylinder 22. The mixing cylinder 22 is fitted in the housing 1. A circulating water flow passage 31 that is a fluid flow passage is formed in the wall of the housing 1 so as to surround the combustion cylinder 21, and an inflow port 32 of the circulating water flow passage 31 is provided at one end of the outer wall of the housing 1 and an inflow port 32. Is connected to the water pump 33. An outlet 35 of the circulating water flow path 31 is provided at the other end of the outer wall of the housing 1, and the outlet 35 is connected to a heat exchanger 34 provided in the passenger compartment. The heat exchanger 34 and the water pump 33 are connected. The circulating water, which is a fluid flowing through the circulating water flow path 31, is heated by the heat of the high-temperature gas ejected from the combustion cylinder 21, and is carried to the heat exchanger 34 by the operation of the water pump 33. A blower 36, which is close to the heat exchanger 34 and sends air to the passenger side for heat exchange in the heat exchanger 34, is provided.

The mixing cylinder 22 is composed of inner and outer double cylinders, and the inner cylinder 24 has a combustion cylinder 21 side end face closed by a top plate 25, and the other side end face open. Six slit-shaped combustion air introduction holes 27 for introducing air into the space between the outer cylinder 23 and the inner cylinder 24 (hereinafter referred to as the inside of the mixing cylinder) are formed at symmetrical positions on the peripheral wall of the inner cylinder 24. . An air supply path 12 is formed in the wall of the housing 1 so as to communicate with the other open end surface of the inner cylinder 24. An air supply port 13 communicating with the air supply passage 12 is provided in the lower portion of the housing 1. The air supply port 13 is connected to an air pump 61 which is an air supply means. The air pump 61 is connected to the control device S that constitutes the exhaust control means 62 and the air control means 82.

The housing 1 facing the air supply passage 12
A flame sensor 72, which is combustion detection means for detecting flame light radiated by combustion, penetrates the wall, and its detection surface faces the top plate 25 of the inner cylinder 24. Combustion cylinder 2 on the top plate 25
A plurality of pores 26 for introducing the flame light from No. 1 into the detection surface of the frame sensor 72 are formed. The frame sensor 72
Is connected to the control device S that constitutes the heating control means 73, and outputs a binary detection signal indicating the presence or absence of flame to the heating control means 73.
And is supplied with electric power from the heating control means 73.

A rod-shaped glow plug 71 serving as a heating means that penetrates through the outer cylinder 23 constituting the mixing cylinder 22 and the housing 1.
Is provided, and the tip portion thereof reaches the inside of the outer cylinder 22. The glow plug 71 is connected to a power source B that supplies electricity to the glow plug 71 via a control device S that constitutes the heating control means 73. Around the glow plug 71, a first vaporizing member 41 formed in the shape of a plate-like ceramic fiber into a cylindrical shape is disposed close to the glow plug 71. The first vaporizing member 41
A second vaporizing member 42, which is made of the same material as the above and is formed into a cylindrical shape, is joined to the inner circumference of the outer cylinder 23. The outer cylinder 23 side of the first vaporizing member 41 is connected to the first vaporizing member 42. An opening at one end of a fuel supply pipe 54 constituting the fuel supply means 5 is in contact with the first vaporization member 41,
The other end of the fuel supply pipe 54 is connected via a shutoff valve 53 to a fuel pump 52 provided in the fuel tank 51 by a pipe 55, and these constitute the fuel supply means 5. Shut-off valve 5
3 and the fuel pump 52 are connected to the fuel control means 81 which constitutes the control device S.

In the operation of the combustion type heater, first, the fuel pump 52 is operated to supply the fuel from the fuel tank 51 to the first vaporizing member 41, and then the second vaporizing member 41 is further vaporized from the first vaporizing member 41. The fuel spreads to the member 42. The glow plug 71 is energized from the power source B via the control device S.
Heats the vaporization members 41, 42. As a result, the vaporization of the fuel spread over the vaporization members 41, 42 is promoted, and the vaporized fuel diffuses into the mixing cylinder 22. On the other hand, the air pump 6
1 operates, and air is supplied from the air supply port 13 to the air supply path 1
It is supplied to the inside of the mixing cylinder from the air introduction port 27 via 2 and becomes a mixed gas of air and the fuel. The glow plug 72 ignites the mixed gas to start combustion. After ignition, the radiant heat from the flame raises the temperature of the second vaporizing member 42 to further promote the vaporization of the fuel, and the combustion is stabilized.

The operation of the combustion type heater when it is stopped is shown in the flowchart of FIG. 2 and FIGS. 3 (A), 3 (B),
This will be described with reference to the time chart of FIG. When a combustion stop command is input to the control device S (step 101 in FIG. 2), the exhaust control means 62 counts the time Tp (set to 180 seconds in this embodiment) from the combustion stop to the end of forced exhaust of vaporized fuel. Timer p to start (step 102 in FIG. 2) and close the shutoff valve (step 1 in FIG. 2).
03), the supply of fuel is stopped (FIG. 3 (A)). At the same time, the exhaust control means 62 maximizes the air pump capacity (see FIG.
Step 104) Supply the maximum supply amount of air that is the preset supply amount (FIG. 3B) (In the example of FIG. 3, the air pump capacity immediately before the combustion stop command is input is also maximum, and before and after the combustion stop command is input. Is constant)).

After the fuel supply is stopped, the fuel remaining in the vaporizing members 41 and 42 continues combustion for a while, and then is blown off by the supplied air. When the frame sensor 72 detects the stop of combustion (step 105 in FIG. 2), the heating control means 7
3 energizes the glow plug 71 (step 106 in FIG. 2,
3C), the timer 1 for counting the energization time T1 of the glow plug 71 (set to 40 seconds in this embodiment) is started (step 107 in FIG. 2). The glow plug 71 heats the vaporizing members 41 and 42 to promote vaporization of the fuel remaining in the vaporizing members 41 and 42 after the combustion is stopped.
The air pump 61 compulsorily exhausts the vaporized fuel from the exhaust port together with the maximum supply amount of air which is a preset supply amount.
When the timer 1 counts the T1 (step 108 in FIG. 2), the heating control means 73 stops energizing the glow plug 71 (FIG. 3 (C)). When the timer p counts Tp (step 110 in FIG. 2), the exhaust control means 6
2 stops the air pump 61 (step 11 in FIG. 2).
1), the air supply is stopped (FIG. 3 (B)), and the combustion type heater is stopped. The air supplied after the combustion stop command is input also plays a role of cooling the burner 2, and the temperature of the burner 2 decreases to near room temperature when the air supply is stopped.

FIG. 3 (D) shows the amount of evaporative emission generated in the combustion type heater, and the effect of reducing the amount of evaporative emission is remarkably recognized as compared with the conventional combustion type heater already shown. To be Also, the frame sensor 7
2 detects the stop of combustion and then energizes the glow plug 71, so that the temperature of the glow plug 71 can be prevented from rising excessively.

(Embodiment 2) Another combustion type heater of the present invention will be described. The difference from the combustion type heater described in the first embodiment is only the control sequence when the combustion type heater is stopped, so only the operation when stopped is the flow chart of FIG. 4 and FIG. ), And the time chart of FIG.

When a combustion stop command is input to the control device S (step 201 in FIG. 4), the fuel control means 81 starts counting by the timer 2 which counts the fuel stop preparation time T2 (set to 10 seconds in this embodiment). (Step 4 in Figure 4)
2) From the fuel supply amount before the combustion stop command, which is before the fuel stop preparation time, inputs the fuel supply amount supplied by the fuel pump 52 (the fuel supply amount is the maximum in the illustrated example) to Qf (the present embodiment). The amount of air supplied by the air control means 82 is reduced to 30% of the fuel supply amount before the combustion stop command is input. (In the illustrated example, the air supply amount is the maximum) to Qa (in the present embodiment, it is set to 30% of the air supply amount before the combustion stop command is input) (step 203 in FIG. 4). This weakens combustion while maintaining an appropriate air-fuel ratio, and reduces the amount of fuel that spreads to the vaporization members 41, 42. The timer 2 counts T2 (Fig. 4
In step 204), the fuel control means 81 closes the shutoff valve (step 205 in FIG. 4) and stops the fuel supply (FIG. 5 (A)). The air control means 82 starts counting by the timer 3 which counts the time T3 (set to 60 seconds in this embodiment) from the stop of the fuel supply to the start of the forced exhaust, and the exhaust control means 62. Is a timer p which counts the time Tp (set to 180 seconds in this embodiment) from the stop of fuel supply to the end of forced exhaust of vaporized fuel.
Counting is started (step 206 in FIG. 4).

Even after the supply of fuel is stopped, weak combustion continues for a while due to the fuel remaining in the vaporizing members 41, 42, and then a very small amount of fuel is blown off in a state of remaining in the vaporizing members 41, 42. When the frame sensor 72 detects the stop of combustion (step 208 in FIG. 4) before T3 has elapsed (step 207 in FIG. 4), the heating control means 73 energizes the glow plug 71 (steps 209 in FIG. 4, FIG. 5). (C)), the timer 1 for counting the energization time T1 of the glow plug 71 (set to 30 seconds in this embodiment) is started (step 210 in FIG. 2). The glow plug 71 is the vaporization member 4
The vaporization of the fuel remaining in the vaporization members 41 and 42 is promoted after the combustion is stopped by heating 1 and 42. T3 has passed (Fig. 4
Step 211) and the exhaust control means 62 maximize the air pump capacity (step 212 in FIG. 4) to supply the maximum supply amount of air which is the preset supply amount (FIG. 5 (B)). The vaporized fuel is preset to be supplied. Forced exhaust is performed from the exhaust port 11 together with the maximum supply amount of air. The timer 1 is T
When 1 is counted (step 213 in FIG. 4), the heating control means 73 stops energizing the glow plug 71 (FIG. 5).
(C)). When the timer p counts Tp (step 215 in FIG. 4), the exhaust control unit 62 stops the air pump 61 (step 216 in FIG. 4) to stop the air supply (FIG. 3 (B)), and the combustion type heat -Ta stops. The air supplied after the combustion stop command is input also plays a role of cooling the burner, and when the air supply is stopped, the burner is heated to near room temperature.
The temperature of the na decreases.

If combustion by the fuel remaining in the vaporizing members 41 and 42 continues after T3, the exhaust control means 62 maximizes the air pump capacity after T3 (step 217 in FIG. 4). A supply amount of air is supplied (FIG. 5 (B)). Very weak combustion continues for a while due to the fuel remaining in the vaporizing members 41 and 42, and is blown out by the maximum supply amount of air. When the flame sensor 72 detects the stop of combustion (step 218 in FIG. 4), the heating control means 73 energizes the glow plug 71 (step 219 in FIG. 4) and counts the energization time of the glow plug 71. Counting is started (step 220 in FIG. 4). The glow plug 71 heats the vaporizing members 41 and 42 to accelerate vaporization of the fuel remaining in the vaporizing members. The vaporized fuel is forcibly exhausted from the exhaust port 11 together with the maximum supply amount of air. The process after step 213 is as described above.

FIG. 5 (D) shows the amount of evaporative emission generated in the above combustion type heater, and the effect of reducing the amount of evaporative emission generated is remarkably recognized as compared with the conventional combustion type heater. By weakening the combustion and reducing the amount of fuel that spreads to the vaporization members 41, 42 during the fuel stop preparation time,
Furthermore, since the amount of fuel remaining in the vaporization members 41, 42 when combustion is stopped is reduced, the energization time of the glow plug 71 can be shortened. In addition, the fuel supply amount and the air supply amount decrease during the fuel stop preparation time to maintain an appropriate air-fuel ratio, thereby preventing deterioration of exhaust emission.

(Embodiment 3) Still another embodiment of the present invention will be described. The difference from the combustion type heater described in the second embodiment is only the control sequence of the control device S when the combustion type heater is stopped, so only the operation when stopped is the flow chart of FIG. This will be described with reference to the time charts of FIGS. 7 (A) and 7 (B).

A combustion stop command is input (step 3 in FIG. 6).
01) and the fuel control means 81 counts the fuel stop preparation time T2 (set to 10 seconds in this embodiment) and the timer 2
Is started (step 302 in FIG. 6), and the amount of fuel supplied by the fuel pump 52 is changed from the fuel supply amount before the combustion stop command is input to Qf (before the combustion stop command is input in this embodiment). It is reduced to 30% of the fuel supply amount), and the air control unit 82 changes the air supply amount supplied by the air pump 61 from the air supply amount before the combustion stop command is input to Qa (combustion stop in this embodiment). The supply amount is reduced to 30% of the air supply amount before the command is input (step 303 in FIG. 6). This weakens combustion while maintaining an appropriate air-fuel ratio, and reduces the amount of fuel that spreads to the vaporization members 41 and 42. When the timer 2 counts T2 (step 304 in FIG. 6), the fuel control means closes the shutoff valve (step 305 in FIG. 7) and stops the fuel supply (FIG. 7 (A)).

In this combustion type heater, the air control means 82 is set so as to monotonically decrease the air supply amount during the time from the stop of the fuel supply to the stop of the combustion.
The time from the stop of the fuel supply is divided into a first half time T4 (25 seconds in this embodiment) and a second half time T5 (35 seconds in this embodiment), and the air supply amount is Qa during T4, and T
During the period of 5, the air supply rate was reduced at a constant slope. When the fuel supply is stopped, the air pump 61 continues to supply air at the supply amount of Qa. The air control means 82 starts counting by the timer 4 for counting T4, and the exhaust control means 62 sets a time Tp (in this embodiment, set to 180 seconds) from the stop of fuel supply to the end of forced exhaust of vaporized fuel. The counting of the counting timer p is started (step 306 in FIG. 6). Even after the supply of the fuel is stopped, the very small amount of fuel remaining in the vaporizing members 41 and 42 causes extremely weak combustion for a while, but the amount of fuel vaporized gradually decreases. When T4 has passed (step 307 in FIG. 6), the air control means 82
Controls the air pump 61 so as to supply a supply amount of air according to the equation (1), where t is the time after the elapse of T4 (step 308 in FIG. 6), and starts the counting of the timer 5 for counting T5. Q = Qa− (Qa / T) × t (1) Since the vaporized fuel decreases and the supply amount of the supplied fuel also decreases, the combustion weakens while maintaining an appropriate air-fuel ratio even after the fuel is stopped, and the vaporizing member The amount of fuel remaining in is reduced. Then, a very small amount of fuel is vaporized by the vaporization members 41, 42.
Blows off while remaining in.

Before T5 elapses (step 310 in FIG. 6)
When the flame sensor 72 detects the stop of combustion (step 311 in FIG. 6), the heating control means 73 causes the glow plug 71.
(Step 312 in FIG. 6, FIG. 7C), and the timer 1 for counting the energization time T1 of the glow plug (set to 25 seconds in this embodiment) is started (step 313 in FIG. 6). ). The glow plug 71 heats the vaporizing members 41 and 42 to promote vaporization of the fuel remaining in the vaporizing members 41 and 42. When T5 elapses (step 314 in FIG. 6), the exhaust control means 62 maximizes the air pump capacity (step 315 in FIG. 6) to supply the maximum supply amount of air (FIG. 7 (B)) and the vaporized fuel to the air pump 61. Performs forced exhaust from the exhaust port 11 together with the maximum supply amount of air that is a preset supply amount. When the timer 1 counts T1 (step 316 in FIG. 6), the heating control means 73 stops energizing the glow plug 71 (step 31 in FIG. 6).
7, FIG. 7 (C)). When the timer p counts Tp (step 318 in FIG. 6), the air pump 61 is stopped (step 319 in FIG. 6) and the air supply is stopped (FIG. 7).
(B)) The combustion type heater is stopped. The air supplied after the combustion stop command is input also plays a role of cooling the burner 2, and when the supply of air is stopped, the burner 2 is heated to near room temperature.
The temperature will drop.

When the combustion due to the fuel remaining in the vaporizing members 41, 42 continues to be continued after T5, the air control means 82 maximizes the air pump capacity after T5 (see FIG. 6). Step 320) Supply maximum supply of air. Combustion continues for a while due to the fuel remaining in the vaporization members 41 and 42, and is blown off by the maximum supply amount of air. The frame sensor 72 detects the stop of combustion (FIG. 6).
(Step 321) and the heating control means 73 energize the glow plug (step 322 in FIG. 6), and the timer 1 for counting the energization time of the glow plug 71 starts counting (step 323 in FIG. 6). The glow plug 71 heats the vaporizing members 41 and 42 to promote vaporization of the fuel remaining in the vaporizing members 41 and 42. The vaporized fuel is forcibly exhausted from the exhaust port 11 together with the maximum supply amount of air. The process after step 316 is as described above.

FIG. 7D shows the amount of evaporative emission generated in the combustion type heater, and the effect of reducing the amount of evaporative emission generated is remarkably recognized as compared with the conventional combustion type heater. Further, the combustion is weakened during the fuel stop preparation time, and the supply amount of air supplied after the fuel stop preparation time is monotonically decreased to maintain an appropriate air-fuel ratio, thereby burning the fuel remaining in the vaporization members 41 and 42. As a result, the amount of fuel remaining in the vaporization member at the time of stopping combustion can be made extremely small because the amount can be efficiently reduced. Therefore, the energization time of the glow plug 71 can be shortened. Moreover, since the proper air-fuel ratio is maintained until the combustion is stopped, deterioration of exhaust emission is prevented.

In each of the above embodiments, the frame sensor is used as the combustion detecting means, but the temperature measuring resistor is arranged in the burner to measure the temperature in the burner. The presence or absence of combustion may be detected.

Although the glow plug is used as the heating means in each of the above embodiments, the heating means may be provided separately from the glow plug.

In each of the above embodiments, the forced air exhaust is started by maximizing the air supply amount from the time when the predetermined time counted by the air supply means has elapsed by the timer, but the time when the flame sensor detects the stop of combustion. You may make it start from.

[0041]

As described above, according to the combustion type heater of the present invention, it is possible to reduce the generation of evaporative emission after the operation of the combustion type heater is stopped.

[Brief description of drawings]

FIG. 1 is an overall view of a combustion type heater of the present invention.

FIG. 2 is a flowchart showing the operation of the combustion type heater of the present invention.

3 (A), (B) and (C) are combustion type heat exchangers of the present invention.
(D) is a time chart showing the effect of the combustion type heater.

FIG. 4 is a flow chart showing the operation of another combustion type heater of the present invention.
It is a chart.

5 (A), (B) and (C) are time charts showing the operation of another combustion type heater of the present invention, and (D) shows the effect of the combustion type heater. It is a time chart.

FIG. 6 is a flowchart showing the operation of another combustion type heater of the present invention.

7 (A), (B) and (C) are time charts showing the operation of still another combustion type heater of the present invention, and (D).
Is a time chart showing the effect of the combustion heater.

FIG. 8 is an overall view of a conventional combustion type heater.

FIG. 9 is a flowchart showing the operation of a conventional combustion type heater.
It is

10A and 10B are time charts showing the operation of the conventional combustion type heater, and FIG. 10C is the combustion type heater.
It is a time chart showing the problems of the computer.

[Explanation of symbols]

1 housing 2 burners 3 Circulating water flow path (fluid flow path) 41 First Vaporizing Member (Vaporizing Member) 42 Second vaporizing member (vaporizing member) 5 Fuel supply means 6 forced exhaust 61 Air pump (air supply means) 62 Exhaust control means 7 Residual fuel vaporization promotion means 71 Glow plug (heating means) 72 Frame sensor (combustion detecting means) 73 Heating control means 8 Residual fuel reduction means 81 Fuel control means 82 Air control means S control device

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References: Kaihei 3-71251 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F23N 5/20 F23D 11/44 F23N 5 / twenty four

Claims (4)

(57) [Claims] 1. A burner for heating the fluid in a housing provided with a fluid flow path through which the fluid to be heated flows, and a vaporization member for vaporizing the fuel used for combustion by the burner. In a combustion type heater comprising fuel supply means for supplying fuel to the vaporization member and air supply means for supplying air mixed with vaporized fuel, vaporization of fuel remaining in the vaporization member after combustion is stopped The residual fuel vaporization promoting means for promoting combustion, the forced exhaust means for forcibly exhausting the vaporized fuel, and the combustion
Reduces the fuel remaining in the vaporization member when stopped
A residual fuel reducing means for providing, the residual fuel reducing means
Before the fuel supply means stops the fuel supply.
The fuel supply means supplies the fuel during the set fuel stop preparation time.
The amount of fuel supplied depends on the fuel before the fuel stop preparation time.
The fuel supply means is controlled so that it is less than the supply amount of
Control means for controlling, fuel stop preparation time and fuel
During the time from when the supply of
The amount of air supplied by the air supply means is the above fuel stop preparation
Above to reduce the amount of air supply before time
A combustion heater comprising: an air control means for controlling an air supply means . 2. The combustion type heater according to claim 1,
The residual fuel vaporization promoting means includes heating means for heating the vaporizing member, combustion detecting means for detecting the presence or absence of combustion in the burner, and heating when the combustion detecting means detects that combustion has stopped. Heating control means for operating the means, the forced exhaust means, the air supply means, and an exhaust control means for controlling the air supply means to supply air at a preset supply amount after combustion is stopped. Combustion type heater composed of. 3. The combustion type heater according to claim 1 , wherein the air control means is a fuel supply means.
The time from the stop of fuel supply to the stop of combustion
Combustion type heater set so that the amount of air supplied is constant . 4. The combustion type heater according to claim 1 or 2 , wherein the air control means is a fuel supply means.
The time from the stop of fuel supply to the stop of combustion
A combustion-type heater set so that the amount of air supplied in the air monotonously decreases .