JP3210269B2 - Combustion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device for supplying gas and air to a burner while controlling a ratio between a gas flow rate and an air flow rate (hereinafter referred to as an air-fuel ratio).

[0002]

2. Description of the Related Art FIG. 10 is a block diagram showing a configuration of a combustion control device disclosed in Japanese Patent Application Laid-Open No. 58-224225 (hereinafter referred to as Document 1). In FIG. 10, reference numeral 1 denotes a blower that supplies air, and constitutes an air volume variable mechanism by controlling the number of rotations. Reference numeral 2 denotes an air-side throttle provided in the air passage, which generates a differential pressure at both ends according to the amount of air. Reference numeral 3 denotes a gas-side throttle provided in the gas passage, which generates a differential pressure at both ends according to the gas amount. Reference numeral 4 denotes a mixing section where the air passage and the gas passage merge, and guides a mixed gas of gas and air to the burner 5. A heat exchanger 6 heats the water passed through the pipe. Reference numeral 7 denotes a thermistor, which outputs an electric signal corresponding to the outlet temperature at the outlet of the heat exchanger 6. Reference numeral 8 denotes a gas proportional valve, and a movable iron core placed in the coil continuously adjusts the opening of the gas valve according to the current flowing through the electromagnetic coil. Reference numeral 9 denotes a temperature setting device, which sets the tapping temperature by manually rotating the variable resistor. Reference numeral 10 denotes a tap water temperature control circuit which amplifies a signal difference between the thermistor 7 and the temperature setter 9 and adjusts the current of the electromagnetic coil of the gas proportional valve 8 so as to reduce the amount of gas so that the tap water temperature becomes equal to the set temperature. Adjust automatically. A differential pressure detector 11 detects a pressure difference between the upstream of the air-side throttle 2 and the upstream of the gas-side throttle 3, and outputs an electric signal proportional to the differential pressure. Reference numeral 12 denotes an air-fuel ratio control circuit, which receives a signal from the differential pressure detector 11 and has a positive differential pressure (pressure P _A upstream of the air-side throttle 2> gas-side throttle 5).
When the pressure reaches the upstream pressure P _G ), the rotation speed of the blower 1 is reduced by the rotation speed control circuit 14 so that the differential pressure becomes negative (air-side throttle 2).
When the pressure P _{A at} the upstream side <P _{G at} the upstream side of the gas-side throttle 5), the rotation speed control circuit 14 acts to increase the rotation speed of the blower 1. Further, the air-fuel ratio control circuit 12
It has an integral element 13 and works to make the steady-state deviation of the differential pressure zero.

In this combustion control device, an air amount proportional to the gas amount adjusted by the gas proportional valve 8 is supplied. Also,
Due to the integration element 13 of the air-fuel ratio control circuit 12, the difference between the pressure upstream of the air-side throttle 2 and the pressure upstream of the gas-side throttle 5 approaches zero as much as possible.

FIG. 11 is a longitudinal sectional view showing a configuration of a differential pressure detector of the combustion control device disclosed in Reference 1. As shown in FIG. 11, the upper case 21, the lower case 22, and the diaphragm 23 form a pressure chamber A24 and a pressure chamber B25. The upstream pressure of the air-side throttle 2 and the upstream pressure of the gas-side throttle 3 are respectively guided from the pressure introduction holes A26 and B27. The diaphragm 23 includes a pressure receiving plate A28 and a pressure receiving plate B.
29, and is fixed by a fixing pin 30 at the center. Non-magnetic core guide 3 is provided on upper case 21.
1 are provided integrally. The core guide 31 guides the core 32 in contact with the fixing pin 30. Core Guide 3
A coil 33 of an operation transformer is fixed to the outside of 1. The diaphragm 23 and the core 32 are
It is supported by a spring 36 between an adjusting screw 34, a spring receiver 35, and a pressure receiving plate B29, which are screw-coupled to the pressure sensor, and is adjusted so that the output signal of the operation transformer becomes zero when the pressure difference is zero.

In the differential pressure detector 11, when a differential pressure is generated between the pressure chamber A24 and the pressure chamber B25, the diaphragm 2
3 is displaced, and an electric signal corresponding to the displacement is output from the secondary coil of the operation transformer.

FIG. 12 shows a configuration of a control device (hereinafter, referred to as a gas flow control device) disclosed in Japanese Patent Application Laid-Open No. 63-53615 (hereinafter referred to as Reference 2) for controlling the weight flow rate of two gases. FIG. FIG. 12 shows a case where the present invention is used for an internal combustion engine for a vehicle. As shown in FIG. 12, gasoline stored in a gasoline tank 42 passes through a gasoline filter 44,
It is led to 6. The pressure regulator 48 regulates the pressure of gasoline supplied to the injector 52 through the fuel line 50.
The injection device 52 is mounted to inject gasoline into an outlet body 54 of a carburetor that can be mounted on an intake manifold 55. The outlet body 54 is provided with a throttle valve below the point at which the injector 52 injects gasoline into the outlet body 54. A fuel return line 56 is provided between pressure regulator 48 and gasoline tank 42 to divert excess gasoline to gasoline tank 42.

On the upper surface of the outlet body 54, an outlet body cover 60 is detachably attached to the outlet body 54 by a combination 62 of a wing nut and a stem. Air conduit 64 directs ambient air to outlet fuselage cover 60 and provides the amount of air required by the engine for combustion during operation.
An air filter 66 at the end of the air conduit 64 that opens to the ambient air serves to prevent particulate matter from entering the tube from the air flow. Air weight sensor 6
8 detects the weight flow of air in the air conduit 64 and outputs a signal representing the weight flow of air in the air conduit 64.

[0008] Similarly, the natural gas conduit 70 is used to prepare the engine for combustion when operating on natural gas rather than gasoline.
The natural gas is directed to the outlet fuselage cover 60 for mixing with air. A natural gas weight sensor 72 disposed within the natural gas conduit 70 detects the natural gas weight flow rate within the natural gas conduit 70 and outputs a signal indicative of the natural gas weight flow rate within the natural gas conduit 70.

[0009] Natural gas is supplied from a pressurized tank 76 to a servo valve 74. The pressurized tank 76 is provided with a manual shutoff valve 78. Natural gas is guided to the pressure sensor 80 through the piping. Pressure sensor 80 cooperates with solenoid shutoff valve 82 to provide natural gas to outlet body 54 if the line pressure falls below a predetermined level indicating that the engine is not sufficient to operate the engine with natural gas. Cut off the flow. To adjust the line pressure, a pressure sensor 8
0 and the natural gas flow between the solenoid shutoff valve 82
A pressure regulator 84 is arranged. Natural gas is supplied from a solenoid shut-off valve 82 through a diaphragm pressure regulator 86 to the natural gas conduit 70 from an outlet of a servo valve 74.

The operation panel 88 is provided with a toggle switch 90 for manually selecting whether to operate the engine with natural gas or gasoline. Indicator lamp 92 indicates that the engine is operating on natural gas, and indicator lamp 94 indicates that the engine is operating on gasoline.

The output signal of the air weight sensor 68 and the output signal of the natural gas weight sensor 72 are sent to a controller 96 after being appropriately amplified. Natural gas weight sensor 7
2 is sent to the signal conditioner 105. An output of the signal conditioner 105 is connected to an input of the inverting amplifier 106. The output of the inverting amplifier 106 is connected to the variable resistor 102 via the resistor 108. Similarly, the output signal of the air weight sensor 68 is sent to the signal conditioner 104. The output of the signal conditioner 104 is connected to the variable resistor 102 via the resistor 112. Variable resistor 1
The sliding contact arm of 02 is connected to the non-inverting input of the operational amplifier 110. The inverting terminal of the operational amplifier 110 is
It is grounded via a resistor 114. The mixing ratio can be finely adjusted periodically using the variable resistor 102. The output signal of the air weight sensor 68 and the inverted output signal of the natural gas weight sensor 72 are
And the sum of both output signals is compared with the signal on the inverting terminal. The output of the operational amplifier 110 is connected to the servo valve 74.

In the gas flow controller, a signal for maintaining a desired stoichiometric ratio of air and natural gas is sent to a servo valve 74 that controls the flow of natural gas in the natural gas conduit 70. The weight flow of natural gas supplied by servo valve 74 depends on the weight flow of air at the speed at which the engine is running.

[0013]

The combustion control device disclosed in Document 1 is configured as described above, and controls the air-fuel ratio using only the differential pressure detected by the differential pressure detector 11. Therefore, combustion control based on the actual flow rates of air and gas cannot be performed. Further, no means for detecting a failure of the differential pressure detector 11 is provided. For this reason, when the differential pressure detector 11 fails, erroneous control may be performed.

The gas flow control device disclosed in Document 2 is configured as described above, and the air weight sensor 68
And means for detecting a failure of the natural gas weight sensor 72 is not provided. Therefore, when the air weight sensor 68 and the natural gas weight sensor 72 fail, erroneous control may be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a combustion control device that performs combustion control based on actual flow rates of air and gas and that is less likely to perform erroneous combustion control. The purpose is to gain.

[0016]

Means for Solving the Problems The combustion control apparatus according to the first aspect of the present invention, a gas flow rate cell <br/> capacitors provided in the gas flow path, the flow rate for air provided to the air passage A sensor, a flow regulator provided in at least one of the gas flow path and the air flow path, and a gas flow rate sensor and an air flow rate sensor are separately provided and connected to the gas flow path and the air flow path. An air-fuel ratio detector that outputs a signal corresponding to the pressure difference, and a detection signal of a gas flow rate sensor and a signal
A combustion control unit that controls the flow regulator using the detection signal of the flow velocity sensor, and an air-fuel ratio abnormality detection unit that detects an abnormality in the air-fuel ratio based on the output signal of the air-fuel ratio detector. Is what you do.

According to a second aspect of the present invention, the combustion control unit controls the flow rate regulator so that the air-fuel ratio is temporarily changed, and the gas flow rate sensor accompanying the change in the air-fuel ratio. /> capacitors is for the reaction of air flow sensor and the air-fuel ratio detector, characterized in that a failure detecting section detecting a failure of the flow sensor and the air flow sensor gas.

The combustion control apparatus according to the third aspect of the present invention, when the failure detecting section detects a failure, to control the flow regulator with an output signal of the air-fuel ratio detector according to the heat requirements It is a feature.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a block diagram showing a configuration of a fuel control device according to this embodiment. In FIG. 1, reference numeral 151 denotes a controller; 152, a temperature controller that issues a heat request (heat increase request / heat decrease request / status maintenance request) to the controller 151 based on the actual temperature and the set temperature of the control target; Burners 154 are gas regulating valves (flow regulators) for regulating the gas flow supplied to the burners 153, 15.
5 is a gas shut-off valve for shutting off a gas flow path supplied to the burner 153, 156 is an air adjustment valve (flow rate regulator) for adjusting the flow rate of air supplied to the burner 153, 157 is a gas throttle, and 158 is air A throttle 159 is a gas flow rate sensor for detecting the flow rate of gas supplied to the burner 153, and 160
Is an air flow rate sensor for detecting the flow rate of air supplied to the burner 153, and 161 is an air-fuel ratio detector (air-fuel ratio detector)
It is. A gas regulating valve 154, a gas shutoff valve 155, a gas restrictor 157, and a gas flow rate sensor 159 are provided in a gas flow path, and an air regulating valve 156 and an air restrictor 158 are provided.
The air flow sensor 160 is provided in the air flow path.

The controller 151 includes a combustion control circuit (combustion control section) 162, an air-fuel ratio abnormality detection circuit (air-fuel ratio abnormality detection section) 163, and a flow rate sensor failure detection circuit (failure detection section) 164. The combustion control circuit 162 controls the gas regulating valve 154 and the air regulating valve 156 by using the detection signal of the gas flow rate sensor 159 and the air flow rate sensor 160 or the output signal of the air-fuel ratio detecting device 161 to thereby control the air. Temperature controller 1 while controlling fuel ratio
The gas flow rate and the air flow rate supplied to the burner 153 are controlled by controlling the gas regulating valve 154 and the air regulating valve 156 in response to the heat demand of 52. The air-fuel ratio abnormality detection circuit 163 includes the air-fuel ratio detection device 16.
It is determined whether or not the air-fuel ratio is abnormal based on the output signal of No. 1 and, when it is determined that the air-fuel ratio is abnormal, the supply of gas to the burner 153 is stopped. Flow sensor failure detection circuit 16
4 is a combustion control circuit 16 when the gas flow rate and the air flow rate supplied to the burner 153 are controlled to predetermined flow rates.
Issue a command to change the ratio between gas flow rate and air flow rate to 2,
From the response of the gas flow rate sensor 159 or the air flow rate sensor 160 to the command, the gas flow rate sensor 159 is determined.
Alternatively, it is determined whether or not the air flow rate sensor 160 has failed, and if it is determined that the gas flow rate sensor 159 and the air flow rate sensor 160 have failed, the detection of the gas flow rate sensor 159 and the air flow rate sensor 160 From the method of controlling the combustion using the signal, the air-fuel ratio detecting device 161
In this case, the method is switched to a method of controlling combustion using the output signal of (1) to back up.

The gas flow rate sensor 159 and the air flow rate sensor 160 are described in, for example,
It is preferable to use a flow rate sensor having a micromachined diaphragm structure disclosed in Japanese Patent No. 30808.

As shown in FIG. 2, the flow rate sensor having a microfabricated diaphragm disclosed by the present applicant has an opening 171 which does not communicate with the front side by using anisotropic etching in the center of the back side of the silicon substrate 170. Thus, a thin diaphragm 172 is formed on the silicon substrate 170, a thin-film heater element 173 is provided at the center of the surface of the diaphragm 172, and a thin-film temperature-measuring resistance element 17 is provided on both sides of the heater element 173.
4, 175, and an ambient temperature resistance element 176 for measuring the ambient temperature is provided on the substrate portion of the silicon substrate 170. In addition, S shown in the figure is a slit penetrating the diaphragm 172, and the heater element 173 and the temperature measuring resistance element 1
74 and 175 are provided for thermal insulation.

This flow rate sensor detects the heat transfer caused by the gas moving on the heater element 173 which is heated at a specified temperature higher than the ambient temperature detected by the ambient temperature resistance element 176.
74, 175 to detect the flow velocity of the gas. Since it is formed on a very thin diaphragm 172 which is thermally insulated, it has an extremely fast response speed and high accuracy. It is characterized in that it can detect a gas flow velocity and can detect a very small flow velocity.

When a flow sensor having a microfabricated diaphragm disclosed by the present applicant is used as the gas flow sensor 159 and the air flow sensor 160, FIG.
As shown in (a), the heater element 173 and the ambient temperature measuring resistance element 176 and the fixed resistances R1, R
Using the heater bridge circuit 177 composed of
The heater element 173 heats the heater element 173 so as to show a constant temperature rise with respect to the ambient temperature, and as shown in FIG. 3B, the temperature measuring resistance elements 174 and 175 and the fixed resistances R3 and R4. The sensor bridge circuit 178 is used to extract the resistance change of the temperature measuring resistance elements 174 and 175 associated with the temperature rise according to the flow velocity of the fluid as a voltage, and amplify it by a differential amplifier to obtain the fluid. A configuration for outputting a voltage value according to the flow velocity (corresponding to the flow rate since the flow path cross-sectional area is constant) is adopted.

FIGS. 4 and 5 are block diagrams showing an air-fuel ratio detecting device used in the combustion control device of this embodiment. FIG. 4 is a cross-sectional view, mainly showing the internal configuration of the air-fuel ratio detection device. FIG. 5 is a perspective view mainly showing an external configuration of the air-fuel ratio detecting device. FIG. 6 is a configuration diagram showing an enlarged main part of an air-fuel ratio detection device used in the combustion control device of this embodiment. FIG. 6 is a perspective view, and mainly shows a portion that performs air-fuel ratio detection and air-fuel ratio abnormality detection.

4 to 6, reference numeral 121 denotes a main body that forms the outer frame of the air-fuel ratio detecting device 161; and 122, a main body B that forms the outer frame of the air-fuel ratio detecting device 161. Body A1
21 and the main body B122 are adhered to each other.

Also, 123 is a gas chamber, 124 is an air chamber,
Reference numeral 125 denotes a diaphragm, and 126 denotes a projection provided at the center of the diaphragm 125. The gas chamber 123 and the air chamber 124 are partitioned by the diaphragm 125. As the diaphragm 125, for example, Japanese Patent Application Laid-Open No. 61-2562
No. 34 can be used. 127 is a gas input end for introducing gas into the gas chamber 123, and 128 is an air input end for introducing air into the air chamber 124. The gas input end 127 is provided on the main body B122,
The air input end 128 is provided on the main body A121. The gas input terminal 127 is provided with a gas regulating valve 154 and a gas throttle 1.
57 is connected to the gas flow path between
Is connected to the air flow path between the air regulating valve 156 and the air throttle 158. 129 is the air-fuel ratio detecting device 16
1 is a mounting bracket for mounting 1 to another device.
The mounting bracket 129 is provided on the main body B122.

Reference numeral 130 denotes an L-shaped rotary lever, 13
Reference numeral 1 denotes a shaft hole provided at a bending position of the rotary lever 130.
32 is a projection provided on one end side of the rotation lever 130, 133 is an adjustment spring arranged on the other end side of the rotation lever 130, and 134 is an adjustment screw for adjusting the urging force of the adjustment spring 133. It is. A main body A121 is provided in the shaft hole 131.
Is passed through the rotating shaft 135. Shaft hole 131
At a position approximately halfway between the end of the rotating lever 1 and the other end.
30 is in contact with the projection 126 of the diaphragm 125. From the convex portion 126 of the diaphragm 125, the rotation lever 1
When the force applied to 30 changes, the rotation lever 130 is displaced about the rotation shaft 135 passed through the shaft hole 131 as a fulcrum. The rotation lever 130 is provided in the air chamber 124.

136 is a reed switch, 137 is a reed switch holder, 138 is a rotary shaft, 139 is a limit adjustment knob, and 140 is a screw hole provided on the side surface of the main body A121. The reed switch 136 is fixed in a reed switch holder 137, and one end of the rotating shaft 138 is fixed to a limit adjustment knob 139.
The other end is screwed into a reed switch holder 137. Between the rotating shaft 138 and the main body A121 and between the rotating shaft 138 and the reed switch holder 137, a play removing mechanism (not shown) such as a preload spring is attached. When the limit adjustment knob 139 is rotated, the rotation shaft 138 rotates, and the position of the reed switch holder 137 moves in the left and right direction in FIG. Limit adjustment knob 13
9 can be fixed with a headless screw screwed into the screw hole 140. A lead (not shown) is connected to the reed switch 136, and a signal indicating whether or not an air-fuel ratio abnormality has occurred is sent from the reed switch 136 to the air in a controller 151 provided outside the air-fuel ratio detection device 161. It is sent to the fuel ratio abnormality detection circuit 163. The reed switch 136 is provided above the air chamber 124.

Reference numeral 141 denotes an air-fuel ratio abnormality detecting magnet which is disposed to face the reed switch 136;
Is a magnet holder, 143 is a shaft hole provided in the magnet holder 142, 144 is the main body A121 and the air-fuel ratio abnormality detecting magnet 1
And a preload spring (compression spring) disposed between the preload spring and the preload spring.
The magnet 141 for detecting an air-fuel ratio abnormality is fixed in the magnet holder 142, and a rotating shaft fixed to the main body A 121 passes through the shaft hole 143. Air-fuel ratio abnormality detection magnet 141
Is the protrusion 13 of the rotary lever 130 by the preload spring 144.
It is pressed against 2. Projection 13 of rotating lever 130
When the force applied to the air-fuel ratio abnormality detecting magnet 141 changes from 2, the air-fuel ratio abnormality detecting magnet 141 is displaced with the rotating shaft passed through the shaft hole 143 as a fulcrum. Air-fuel ratio abnormality detection
The magnet 141 is provided in the air chamber 124.

Reference numeral 145 denotes a displacement sensor, and 146 denotes an air-fuel ratio detecting magnet disposed so as to face the displacement sensor 145. The displacement sensor 145 is fixed to the main body A121, and the air-fuel ratio detecting magnet 146 is attached to the rotary lever 130 at a substantially intermediate position between the shaft hole 131 and one end. When the rotation lever 130 is displaced, the air-fuel ratio detecting magnet 146 is displaced together with the displacement. A conductor (not shown) is connected to the displacement sensor 145, and a signal corresponding to the air-fuel ratio (differential pressure) is transmitted from the displacement sensor 145 to the controller 1 provided outside the air-fuel ratio detection device 161.
It is sent to a combustion control circuit 162 in 51.

In such an air-fuel ratio detecting device 161, the position of the rotary lever 130 is determined by the balance between the forces of the diaphragm 125, the adjusting spring 133, and the two preload springs 144. However, as the preload spring 144, the air-fuel ratio abnormality detecting magnet 141 is
Since the spring having a small spring constant that can be pressed against the spring 2 is used, and the spring 133 for adjustment has a spring constant considerably larger than that of the preload spring 144, the influence of the preload spring 144 can be substantially ignored. it can. Therefore, the position of the rotary lever 130 is substantially determined by the balance between the forces of the diaphragm 125 and the adjusting spring 133.

That is, such an air-fuel ratio detecting device 16
At 1, the diaphragm 125 is displaced according to the air-fuel ratio. When the diaphragm 125 is displaced, the diaphragm 1
25, the force applied to the rotary lever 130 changes, and the balance between the force of the diaphragm 125 and the adjustment spring 133 changes.
Is displaced with the rotation shaft 135 passed through the shaft as a fulcrum. When the rotation lever 130 is displaced, the protrusion 13
Since the force applied to the air-fuel ratio abnormality detection magnet 141 changes from 2, the air-fuel ratio abnormality detection magnet 141 is displaced about the rotation shaft passed through the shaft hole 143 as a fulcrum. Also, rotating lever 1
When the 30 is displaced, the air-fuel ratio detecting magnet 146 attached to the rotating lever 130 is also displaced with the displacement of the rotating lever 130.

Further, in such an air-fuel ratio detecting device 161, even if the preload spring 144 is fully compressed and the rotary lever 130 is displaced most, the diaphragm 125 can be used.
Is set within a range where the diaphragm 125 is not damaged.

When the air-fuel ratio detecting device 161 is operated, the reed switch holder 137 is moved by rotating the limit adjusting knob 139 before the operation, and the reed switch 136 fixed to the reed switch holder 137 is operated. At a predetermined position. And screw hole 1
Limit adjustment knob 139 with a headless screw screwed into 40
Is fixed. Since the reed switch 136 is used to detect an air-fuel ratio abnormality, here, an air-fuel ratio abnormality occurs during the operation of the air-fuel ratio detection device 161 and the air-fuel ratio abnormality detection magnet 141 is moved to a predetermined position. When displaced, the magnetic force turns the reed switch 136 from OFF to ON
The reed switch 136 is disposed at a position where the reed switch 136 switches from ON to OFF . In the following description, when an air-fuel ratio abnormality occurs during the operation of the air-fuel ratio detection device 161 and the air-fuel ratio abnormality detection magnet 141 is displaced to a predetermined position, the magnetic force turns the reed switch 136 from OFF to ON. At the position where it switches to
A case where the reed switch 136 is OFF when the 36 is disposed, that is, when no air-fuel ratio abnormality has occurred, will be described.

When the air-fuel ratio detecting device 161 is operated, the reed switch 1 is constantly operated or at a constant period (digital sampling period).
36 and an output signal from the displacement sensor 145 are output from an air-fuel ratio abnormality detection circuit 163 and a combustion control circuit 162 in a controller 151 provided outside the air-fuel ratio detection device 161.
Is taken into. When an air-fuel ratio abnormality has not occurred, a signal that the reed switch 136 is OFF is output from the reed switch 136. When an air-fuel ratio abnormality has occurred, a signal that the reed switch 136 is ON is outputted from the reed switch 136. Output from On the other hand, displacement sensor 1
From 45, a signal corresponding to the position of the air-fuel ratio detecting magnet 146 displaced with the displacement of the rotary lever 130, that is, a signal corresponding to the air-fuel ratio is output.

In FIG. 1, the gas flow rate sensor 159
Is shown on the upstream side of the gas regulating valve 154, but the gas flow rate sensor 159 may be located on the downstream side of the gas regulating valve 154. Also,
Although the case where the air flow rate sensor 160 is located on the upstream side of the air adjustment valve 156 is shown, the air flow rate sensor 160 may be located on the downstream side of the air adjustment valve 156.

The controller 1 of such a combustion control device
The operation during the steady combustion of 51 will be described. Also, in FIG.
Although the case where the adjustment valve is provided in each of the gas flow path and the air flow path is shown, the case where the adjustment valve is provided in only one of the gas flow path and the air flow path may be used. As shown in the flowchart of FIG.
The output signal from the first reed switch is read into the air-fuel ratio abnormality detection circuit 163 (step S1). Then, it is determined whether the reed switch is ON or OFF (step S
2) If it is ON, it is determined that the air-fuel ratio is abnormal, the gas regulating valve 154 and the gas shut-off plate 155 are closed (step S3), and the air regulating valve 156 is fully opened (step S4). An alarm is issued (step S5). OFF
If it is determined that the air-fuel ratio is normal, the detection signals of the gas flow rate sensor 156 and the air flow rate sensor 157 are read into the combustion control circuit 162 (step S).
6). By controlling the gas regulating valve 154 and the air regulating valve 156, the gas regulating valve 15 is controlled in response to the heat demand of the temperature controller 152 while controlling the air-fuel ratio.
By controlling the control valve 4 and the air regulating valve 156, the gas flow rate and the air flow rate supplied to the burner 153 are controlled (step S7). Here, the air-fuel ratio abnormality is checked using the ON / OFF signal from the reed switch, but the air-fuel ratio abnormality can be checked using the output signal from the displacement sensor. In that case, the upper and lower limit values may be stored in the memory of the failure detection circuit 164 in advance, and compared with the output signal of the displacement sensor. If the output signal of the displacement sensor exceeds the upper and lower limit values, it is determined that the air-fuel ratio is abnormal. Thereafter, this series of steps is repeatedly performed at a predetermined cycle.

When the controller 151 of such a combustion control device is operated to check whether or not the gas flow rate sensor 159 and the air flow rate sensor 160 are out of order, the controller 151
When the gas flow rate and the air flow rate supplied to the burner 153 are controlled to predetermined flow rates, first, the flow rate sensor failure detection circuit 164 sends the air-fuel ratio detection device 161 to the combustion control circuit 162 as shown in the flowchart of FIG. (Step S) so as to increase (or decrease) the gas flow rate so that the output signal from the displacement sensor of FIG.
11). Then, it is determined whether the detection signal of the gas flow rate sensor 159 has increased (or decreased) by a predetermined amount (step S12), and the detection signal of the gas flow rate sensor 159 has not increased (or decreased) by a predetermined amount. In this case, it is determined that the gas flow rate sensor 159 has failed (step S13). When the detection signal of the gas flow rate sensor 159 has increased (or decreased) by a predetermined amount, it is determined that the gas flow rate sensor 159 has not failed, and the gas flow rate is restored (step S14). Thereafter, the flow rate sensor failure detection circuit 164 sends the air-fuel ratio detection device 1 to the combustion control circuit 162.
A command to increase the air flow rate is issued so that the output signal from the displacement sensor 61 becomes a predetermined value (step S1).
5). Then, it is determined whether the detection signal of the air flow rate sensor 160 has increased (or decreased) by a predetermined amount (step S16), and the detection signal of the air flow rate sensor 160 has not increased (or decreased) by a predetermined amount. In this case, it is determined that the air flow rate sensor 160 has failed (step S17). If the detection signal of the air flow rate sensor 160 has increased (or decreased) by a predetermined amount, it is determined that the air flow rate sensor 160 has not failed, and the air flow rate is restored (step S18). The check as to whether or not the 159 and the air flow rate sensor 160 have failed is terminated. If the gas flow rate sensor 159 and the air flow rate sensor 160 have not failed, the combustion control shown in FIG. 7 is returned again. Also gas here,
The amount of increase or decrease in the air flow rate is such that the combustion is not adversely affected.

On the other hand, if the gas flow rate sensor 159 or the air flow rate sensor 160 has failed, the gas regulating valve 154 and the air regulating valve 156 are returned to their original opening degrees, and then the flow chart of FIG. As shown in (2), first, the output signal from the reed switch of the air-fuel ratio detection device 161 is read into the air-fuel ratio abnormality detection circuit 163 (step S2).
1). Then, it is determined whether the reed switch is ON or OFF (step S22). If it is ON, it is determined that the air-fuel ratio is abnormal, and the gas regulating valve 154 and the gas shut-off plate 155 are closed (step S23). ), The control valve 156 for air is fully opened (step S24), and an alarm is issued (step S25). If it is OFF, it is determined that the air-fuel ratio is normal, and the gas flow rate supplied to the burner 153 is controlled by controlling the gas regulating valve 154 in response to a heat request from the temperature controller 152. (Step S2
6). Thereafter, an output signal corresponding to the air-fuel ratio from the displacement sensor of the air-fuel ratio detection device 161 is read into the combustion control circuit 162 (step S27). Then, it is determined whether the measured value of the air-fuel ratio matches the set value (step S2).
8) If they do not match, it is determined whether the measured value is larger than the set value (step S29). If the measured value is larger than the set value, the air regulating valve 156 is slightly closed (step S29). Step S30). If the measured value is smaller than the set value, the air regulating valve 156 is slightly opened (step S).
31). When the processing in step S30 or step S31 is completed, or when it is determined in step S28 that the measured value of the air-fuel ratio matches the set value, the process returns to step S21, and thereafter, at a predetermined cycle, A series of steps is repeated.

As described above, according to the combustion control device of this embodiment, the output signal from the reed switch of the air-fuel ratio detection device 161 is read into the air-fuel ratio abnormality detection circuit 163, and the reed switch is turned on. Determines that the air-fuel ratio is abnormal, closes the gas regulating valve 154 and the gas shutoff valve 155, fully opens the air regulating valve 156, and issues an alarm. Therefore, when combustion control is performed using the detection values of the gas flow rate sensor 159 and the air flow rate sensor 160, the gas flow rate sensor 159 or the air flow rate sensor 160 fails and an air-fuel ratio abnormality occurs. However, the risk of erroneous combustion control being reduced reduces the safety of the combustion control device.

Further, according to the combustion control device of this embodiment, when the gas flow rate and the air flow rate supplied to the burner 153 are controlled to predetermined amounts, the gas flow rate sensor 1
It is actively checked whether or not 59 and the air flow rate sensor 160 are out of order. For this reason, the safety of the combustion control device is further improved.

Further, according to the combustion control apparatus of this embodiment, it is checked whether or not the gas flow rate sensor 159 and the air flow rate sensor 160 are out of order, and the gas flow rate sensor 159 or the air flow rate sensor 160 is checked. If a failure occurs, combustion is controlled using an output signal from a displacement sensor of the air-fuel ratio detection device 161. For this reason, the reliability of the combustion control device increases.

[0044]

As it is evident from the foregoing description, according to the first aspect of the invention, a gas flow rate sensor provided in the gas passage, and air flow rate sensor provided in the air flow path, the gas flow path and A flow regulator provided in at least one of the air flow paths,
An air-fuel ratio detector that is provided separately from the gas flow rate sensor and the air flow rate sensor, and that is connected to the gas flow path and the air flow path and outputs a signal corresponding to the differential pressure between the gas flow rate sensor and the air flow rate sensor; A combustion control unit that controls the flow regulator using the detection signal of the gas flow rate sensor and the detection signal of the air flow rate sensor, and an air-fuel ratio abnormality that detects an air-fuel ratio abnormality based on the output signal of the air-fuel ratio detector Since it has a detection unit,
Combustion control based on the actual flow rate can be performed using the detection signals of the flow velocity sensor and the air flow velocity sensor, and even if the gas flow velocity sensor or the air flow velocity sensor fails and an air-fuel ratio abnormality occurs, an error is detected. Thus, the risk of performing the combustion control is reduced, and a highly safe combustion control device can be obtained.

[0045] According to the second aspect of the present invention, by controlling the flow rate regulator as combustion control unit is to temporarily change the air-fuel ratio, gas flow rate sensor according to the modification in an air-fuel ratio, air
From the reaction of the flow velocity sensor and the air-fuel ratio detector, since the provided failure detecting section detecting a failure of the flow rate <br/> sensor and air flow sensor gas, gas for flow sensors and air
It is possible to positively check whether or not the flow rate sensor is out of order, so that a safer combustion control device can be obtained than in the case of the first aspect.

According to the third aspect of the present invention, when the failure detecting section detects a failure, the flow regulator is controlled by using the output signal of the air-fuel ratio detector in accordance with the heat request.
Check whether the flow velocity sensor and the air velocity sensor have failed, and if the gas velocity sensor or the air velocity sensor has failed, use the output signal of the air-fuel ratio detection device. The combustion can be backed up and controlled
The reliability of the combustion control device is increased.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a combustion control device according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram of a flow rate sensor used in the combustion control device according to the first embodiment of the present invention.

FIG. 3 is a circuit diagram of a flow rate sensor used in the combustion control device according to the first embodiment of the present invention.

FIG. 4 is a sectional view showing an air-fuel ratio detection device used in the combustion control device according to the first embodiment of the present invention.

FIG. 5 is a perspective view showing an air-fuel ratio detection device used in the combustion control device according to the first embodiment of the present invention.

FIG. 6 is an enlarged perspective view showing a main part of an air-fuel ratio detection device used in the combustion control device according to the first embodiment of the present invention.

FIG. 7 is a flowchart showing an operation when controlling combustion in the combustion control device according to the first embodiment of the present invention.

FIG. 8 is a flowchart showing an operation when checking whether or not the gas flow rate sensor and the air flow rate sensor have failed in the combustion control device according to the first embodiment of the present invention.

FIG. 9 shows an operation in the case where the gas flow rate sensor and the air flow rate sensor in the combustion control apparatus according to the first embodiment of the present invention are out of order and the combustion is controlled using the output signal of the air-fuel ratio detection apparatus. It is a flowchart which shows.

FIG. 10 is a block diagram showing a configuration of a conventional combustion control device.

FIG. 11 is a longitudinal sectional view showing a configuration of a differential pressure detector used in a conventional combustion control device.

FIG. 12 is a configuration diagram of a conventional gas flow control device.

[Explanation of symbols]

 154 Gas regulating valve (flow regulator) 156 Air regulating valve (flow regulating valve) 159 Gas flow rate sensor 160 Air flow rate sensor 161 Air-fuel ratio detector (air-fuel ratio detector) 162 Combustion control circuit (combustion control unit) 163 Air-fuel ratio abnormality detection circuit (air-fuel ratio abnormality detection unit) 164 Flow velocity sensor failure detection circuit (failure detection unit)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F23N 5/18 F23N 1/02

Claims (3)

(57) [Claims] 1. A gas for flow rate sensor provided in the gas passage, and air flow rate sensor provided in the air flow path, a flow regulator provided in at least one of the gas flow passage and the air passage And the gas flow rate sensor and the air
An air-fuel ratio detector which is provided separately from the flow rate sensor and is connected to the gas flow path and the air flow path and outputs a signal corresponding to a differential pressure between the flow rate sensor and the gas flow rate < A combustion control unit that controls the flow regulator using a detection signal of the sensor and a detection signal of the air flow rate sensor, and detects an air-fuel ratio abnormality based on an output signal of the air-fuel ratio detector. A combustion control device comprising: an air-fuel ratio abnormality detection unit. 2. The combustion control device according to claim 1, wherein
The combustion control unit controls the flow regulator so as to temporarily change the air-fuel ratio, and from the reaction of the gas flow rate sensor, the air flow rate sensor, and the air-fuel ratio detector accompanying the change of the air-fuel ratio. A combustion control device provided with a failure detection unit for detecting a failure of the gas flow rate sensor and the air flow rate sensor. 3. The combustion control device according to claim 2, wherein
A combustion control device, wherein when the failure detection unit detects a failure, the flow controller is controlled using an output signal of the air-fuel ratio detector in accordance with a heat request.