Forced intake and exhaust combustion equipment

Abstract

To provide a forced air supply / exhaust type combustion device capable of performing, with high reliability, appropriate operation control of a burner corresponding to a block-up degree of an air supply path or an air exhaust path or an air quantity.SOLUTION: A controller 30 of a forced air supply / exhaust type combustion device 1 performs operation control of a burner 3 in accordance with a difference (pressure change amount) between an in-actuation pressure detection value which is detected by a pressure sensor 24 while a blower 12 is actuated and a pre-actuation pressure reference value that is a reference value of a pressure prior to actuation start of the blower 12. The controller 30 updates the pre-actuation pressure reference value in a case where a pre-actuation pressure detection value which is detected by the pressure sensor 24 prior to the actuation start of the blower 12 is included in a predetermined range, however, does not update the pre-actuation pressure reference value in a case where the pre-actuation pressure detection value is not included in the predetermined range.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a forced intake and exhaust type combustion device such as a hot air heater. [Background technology]

[0002] In a forced intake and exhaust type combustion device, in which combustion air is supplied to a burner through an air intake passage by operating a blower and combustion exhaust gas generated by the combustion operation of the burner is exhausted through an exhaust passage, a pressure sensor is used to detect the differential pressure between the upstream and downstream sides of an orifice provided in the air intake passage or exhaust passage, and if the detected differential pressure value indicates that the air intake passage or exhaust passage is highly clogged, the burner combustion operation is not started or is stopped, as shown in Patent Document 1, for example.

[0003] In this case, the technology described in Patent Document 1 stores the detected value of the differential pressure before the blower starts operating as the pre-operation pressure value, and then compares the amount of change from the pre-operation pressure value of the detected value of the differential pressure while the blower is operating (operational pressure value) with a predetermined threshold value. If the amount of change becomes smaller than the predetermined threshold value, it is determined that the degree of blockage of the air intake passage or exhaust passage is high, and the burner combustion operation is not started or is stopped.

[0004] Furthermore, for example, Patent Document 2 describes a technology for detecting the air volume generated by a blower supplying combustion air using an air volume detector composed of a pressure sensor, and describes a technology for calibrating the air volume detector using the detection signal of the air volume detector when the blower is stopped. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2000-304255 A [Patent Document 2] Japanese Patent Application Publication No. 8-159464 Summary of the Invention [Problem to be solved by the invention]

[0006] The technologies disclosed in Patent Documents 1 and 2 assume that when the blower is not operating, the air volume at the pressure detection point detected by the pressure sensor is zero (windless state), and estimate the degree of blockage of the air intake or exhaust passage while the blower is operating, and whether the air volume is appropriate, based on the change in the pressure detection value while the blower is operating (the relative pressure change from the pressure detection value when the blower is not operating).

[0007] However, even when the blower is stopped, the air volume at the point where pressure is detected by the pressure sensor may not be zero due to outside wind acting on the air intake or exhaust passage, and in such cases, the pressure detection value of the pressure sensor when the blower is stopped will be affected by the air volume due to outside wind.

[0008] In such a case, even if an attempt is made to detect the degree of blockage of the air intake passage or the exhaust passage or the appropriateness of the air volume based on the amount of change in the pressure detection value while the blower is operating (the amount of change from the pressure detection value when the blower is not operating) using the pressure detection value of the pressure sensor when the blower is not operating as a reference, a false detection will occur. For example, even if the blockage of the air intake passage or the exhaust passage is not very advanced, it may be falsely detected as being highly blocked, which may result in inconvenience such as the burner combustion operation being stopped.

[0009] The present invention has been made in view of the above background, and has an object to provide a forced intake and exhaust type combustion apparatus equipped with a pressure sensor that detects pressure corresponding to the air volume in the air intake or exhaust passage, which is capable of reliably performing appropriate operation control of a burner according to the degree of blockage of the air intake or exhaust passage, or the air volume. [Means for solving the problem]

[0010] In order to achieve the above object, the first aspect of the forced intake and exhaust combustion apparatus of the present invention is as follows: A forced intake and exhaust type combustion device that supplies combustion air to a burner through an air intake path by operating a blower and exhausts combustion exhaust gas generated by the combustion operation of the burner through an exhaust path, a pressure sensor for detecting a differential pressure between an upstream side and a downstream side of an orifice provided in the air supply passage or the exhaust passage; a storage unit that stores and holds a pre-operation pressure reference value that is a reference value of the pressure value detected by the pressure sensor in a stopped state before the blower starts operating; a control unit which acquires an operating pressure detection value, which is a pressure value detected by the pressure sensor during operation of the blower, and controls operation of the burner in accordance with a pressure change amount, which is a difference between the operating pressure detection value and the stored pre-operation pressure reference value, or in accordance with a degree of blockage of the air supply passage or the exhaust passage estimated from the pressure change amount, or in accordance with an air volume of the air supply passage or the exhaust passage estimated from the pressure change amount; an update processing unit that executes a process of updating the pre-operation pressure reference value stored and held in the storage unit, The update processing unit acquires a pre-operation pressure detection value, which is a pressure value detected by the pressure sensor in a stopped state before the operation of the blower is started, and determines whether the pre-operation pressure detection value is within a predetermined range. If the pre-operation pressure detection value is not within the predetermined range, the update processing unit does not update the pre-operation pressure reference value stored and held in the memory unit, and if the pre-operation pressure detection value is within the predetermined range, updates the pre-operation pressure reference value stored and held in the memory unit at least in accordance with the pre-operation pressure detection value. When the pre-operation pressure detection value is included in the predetermined range, the pre-operation pressure detection value is stored as a setting pressure detection value for newly setting the predetermined range, and the predetermined range to be compared with the pre-operation pressure detection value obtained in a stopped state before the blower starts operating is set to a range centered on an average value of a plurality of the setting pressure detection values ​​stored in the past. The present invention is characterized by being configured as above (first invention).

[0011] In the first invention, by appropriately setting the specified range, when the blower is in a stopped state before starting operation and airflow caused by outside wind is generated in the air passage around the orifice, which is one of the air intake and exhaust passages, the pre-operation pressure detection value deviates from the specified range, and when the air passage around the orifice is in a windless state, the pre-operation pressure detection value can be made to be within the specified range.

[0012] Furthermore, if the pre-activation pressure detection value is not within the specified range (if it deviates from the specified range), the pre-activation pressure reference value stored in the memory unit is not updated, so it is possible to prevent the pre-activation pressure reference value from being updated using the pre-activation pressure detection value when the pressure sensor is affected by airflow caused by outside wind.

[0013] Furthermore, when the pre-actuation pressure detection value is within a predetermined range, the pre-actuation pressure reference value is updated at least in accordance with the pre-actuation pressure detection value, so that it is possible to update the pre-actuation pressure reference value to reflect the pre-actuation pressure detection value in a situation where the air passage around the orifice is in a windless state.

[0014] Furthermore, the pressure change amount during operation of the blower is a highly reliable index value corresponding to the degree of blockage of the air intake passage or exhaust passage or the air volume of the air intake passage or exhaust passage. Therefore, by controlling the operation of the burner according to the pressure change amount, or according to the degree of blockage of the air intake passage or exhaust passage estimated from the pressure change amount, or according to the air volume of the air intake passage or exhaust passage estimated from the pressure change amount, it becomes possible to perform appropriate operation control of the burner according to the degree of blockage of the air intake passage or exhaust passage or the air volume with high reliability. In addition, even if a steady drift (offset from the initial state) of the output of the pressure sensor occurs in a windless state, the influence of the drift can be appropriately compensated for and the predetermined range to be compared with the pre-operation pressure detection value can be appropriately set. As a result, whether or not the pre-operation pressure detection value is included in the predetermined range can be used to increase the reliability of indicating whether or not the air passage around the orifice is in a windless state.

[0017] The first bullet above Bright The update processing unit may be configured to update the pre-actuation pressure reference value stored and held in the storage unit to the pre-actuation pressure detection value when updating the pre-actuation pressure reference value stored and held in the storage unit (the 2 invention).

[0018] This makes it possible to appropriately compensate for the effects of drift in the pressure sensor output in windless conditions and variations in the output characteristics, and to appropriately set the pre-activation pressure reference value that corresponds to the value of the differential pressure before and after the orifice detected by the pressure sensor in windless conditions.

[0019] In addition, in order to achieve the above object, a second aspect of the forced intake and exhaust type combustion apparatus of the present invention is as follows: A forced intake and exhaust type combustion device that supplies combustion air to a burner through an air intake path by operating a blower, and exhausts combustion exhaust gas generated by the combustion operation of the burner through an exhaust path, a pressure sensor for detecting a differential pressure between an upstream side and a downstream side of an orifice provided in the air supply passage or the exhaust passage; a storage unit that stores and holds a pre-operation pressure reference value that is a reference value of the pressure value detected by the pressure sensor in a stopped state before the blower starts operating; a control unit which acquires an operating pressure detection value, which is a pressure value detected by the pressure sensor during operation of the blower, and controls operation of the burner in accordance with a pressure change amount, which is a difference between the operating pressure detection value and the stored pre-operation pressure reference value, or in accordance with a degree of blockage of the air supply passage or the exhaust passage estimated from the pressure change amount, or in accordance with an air volume of the air supply passage or the exhaust passage estimated from the pressure change amount; an update processing unit that executes a process of updating the pre-operation pressure reference value stored and held in the storage unit, The update processing unit is configured to obtain a pre-operation pressure detection value, which is a pressure value detected by the pressure sensor in a stopped state before the operation of the blower is started, determine whether the pre-operation pressure detection value is within a predetermined range, and if the pre-operation pressure detection value is not within the predetermined range, count the number of consecutive occurrences of an event of not being within the predetermined range, and if the counted number reaches a predetermined number, update the pre-operation pressure reference value stored and held in the memory unit according to at least the pre-operation pressure detection value, and if the counted number does not reach the predetermined number, not update the pre-operation pressure reference value stored and held in the memory unit (the first embodiment). 3 invention).

[0020] Such 3In this invention, as in the first invention, by appropriately setting the specified range, when the blower is in a stopped state before starting operation and airflow caused by outside wind is generated in the air passage around the orifice, which is one of the air intake and exhaust passages, the pre-operation pressure detection value deviates from the specified range, and when the air passage around the orifice is in a windless state, the pre-operation pressure detection value can be made to be within the specified range.

[0021] Here, even if the air passage around the orifice is windless in a stopped state before the blower starts operating, the pre-operation pressure detection value may constantly deviate from the predetermined range due to a steady drift (offset from the initial state) of the pressure sensor output. On the other hand, in a stopped state before the blower starts operating, the situation in which an airflow caused by outside wind occurs in the air passage around the orifice is generally a temporary situation.

[0022] Therefore, 3 In the present invention, when the pre-actuation pressure detection value is not within a predetermined range (when it deviates from the predetermined range), the pre-actuation pressure reference value is updated at least according to the pre-actuation pressure detection value, with the necessary condition that the number of consecutive occurrences of the event of not being within the predetermined range, which is counted, reaches a predetermined number. This makes it possible to update the pre-actuation pressure reference value by reflecting the pre-actuation pressure detection value (pre-actuation pressure detection value including the influence of drift) in a situation where the air passage around the orifice is in a windless state, when steady drift occurs in the output of the pressure sensor.

[0023] Furthermore, if the counted number does not reach a predetermined number, the pre-activation pressure reference value is not updated, making it possible to prevent the pre-activation pressure reference value from being updated using the pre-activation pressure detection value when the pressure sensor is affected by airflow caused by outside wind.

[0024] Furthermore, the pressure change amount during operation of the blower is a highly reliable index value corresponding to the degree of blockage of the air intake passage or exhaust passage or the air volume of the air intake passage or exhaust passage. Therefore, by controlling the operation of the burner according to the pressure change amount, or according to the degree of blockage of the air intake passage or exhaust passage estimated from the pressure change amount, or according to the air volume of the air intake passage or exhaust passage estimated from the pressure change amount, it becomes possible to perform appropriate operation control of the burner according to the degree of blockage of the air intake passage or exhaust passage or the air volume with high reliability.

[0025] In addition, 3 In the invention, when the pre-actuation pressure detection value is within a predetermined range, as in the first invention, either a configuration in which the pre-actuation pressure reference value is updated at least in accordance with the pre-actuation pressure detection value, or a configuration in which the pre-actuation pressure reference value is not updated may be adopted.

[0026] The above 3 In the present invention, the update processing unit may be configured to set the predetermined range to a range centered on a pre-operation pressure reference value stored and held in the storage unit (the 4 invention). This makes it possible to appropriately set the specified range so that whether or not the pre-activation pressure detection value is included in the specified range depends on whether the air passage around the orifice is in a windless state.

[0027] The above 3 Invention or 4 In the invention, it is preferable that the update processing unit is configured to store the pre-actuation pressure detection value as an update pressure detection value for updating the pre-actuation pressure reference value when the pre-actuation pressure detection value is not included in a predetermined range, and to update the pre-actuation pressure reference value stored in the storage unit in response to the counted number reaching the predetermined number, to an average value of the pre-actuation pressure detection values ​​stored at each of the predetermined number of times (the 5 invention).

[0028] This makes it possible to update the pre-actuation pressure reference value so as to preferably reflect the pre-actuation pressure detection value (pre-actuation pressure detection value including the influence of drift) in a state where the air passage around the orifice is in a windless state, and to reduce the influence of disturbance noise as much as possible. As a result, it is possible to increase the reliability of the pre-actuation pressure reference value as a value equivalent to the pressure difference across the orifice detected by the pressure sensor in a windless state. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing a mechanical configuration of a warm air heater according to an embodiment (first or second embodiment) of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a configuration related to control of the hot air heater of the embodiment. [Diagram 3] 3 is a flowchart showing a process in a first embodiment of the controller shown in FIG. 2; [Figure 4] 5 is a flowchart showing a process of a controller shown in FIG. 2 in a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] [First embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 3. With reference to Figure 1, the forced intake and exhaust type combustion device of this embodiment is, for example, a hot air heater 1. This hot air heater 1 is provided with a main body case 2 arranged indoors, a combustion chamber 4 accommodating a burner 3, a heat exchanger 4a communicating with the combustion chamber 4, and a convection fan 5 that draws in indoor air and blows out hot air.

[0031] An intake cylinder 10 is connected to the combustion chamber 4, and the intake cylinder 10 has an intake passage 10a formed therein, which is an air passage for supplying combustion air to the burner 3. The exhaust cylinder 11 is connected to the combustion chamber 4 through a heat exchanger 4a. The intake passage 10a is connected to the exhaust passage 11a through the combustion chamber 4 and the heat exchanger 4a. Hereinafter, the air passage from the intake passage 10a to the exhaust passage 11a may be collectively referred to as the intake and exhaust passage.

[0032] The intake cylinder 10 extends from the combustion chamber 4 through the indoor space outside the main body case 2 to the outdoors, and its upstream end is opened to the outdoors as an intake port 10b. The exhaust pipe 11 extends from the downstream end of the heat exchanger 4a through the indoor space outside the main body case 2 to the outdoors, and its downstream end is opened to the outdoors as an exhaust port 11b. In the illustrated example of the warm air heater 1, the downstream portion of the exhaust pipe 11 is concentrically arranged inside the upstream portion of the intake cylinder 10. However, the exhaust pipe 11 may be arranged entirely outside the intake cylinder 10.

[0033] A combustion fan 12 is attached to the intake cylinder 10 as a blower that supplies combustion air to the burner 3. An electric motor 12a that drives and rotates the combustion fan 12 is connected to the combustion fan 12. Then, by driving and rotating the combustion fan 12 by the electric motor 12a, outside air (outdoor air) is drawn from the intake port 10b into the intake passage 10a in the intake cylinder 10, and the drawn outside air passes through the combustion fan 12 and is then supplied from the intake passage 10a to the burner 3 in the combustion chamber 4 as combustion air. In this case, by controlling the number of revolutions (rotational speed) of the combustion fan 12, it is possible to increase or decrease the amount of combustion air supplied to the burner 3.

[0034] The burner 3 in this embodiment is a gas burner of a known structure, and is supplied with fuel gas from a fuel gas supply source (not shown) through a gas supply pipe 14 serving as a fuel supply path. The burner 3 is configured to mix the fuel gas supplied from the gas supply pipe 14 with combustion air supplied from an air supply path 10a by the rotational operation of the combustion fan 12, and to combust the mixture obtained by the mixing.

[0035] The gas supply pipe 14 is fitted with two solenoid valves 15a, 15b that can be opened and closed, and a fuel regulating valve 16 such as a proportional valve for adjusting the amount of fuel gas supplied to the burner 3. By controlling the fuel regulating valve 16 while controlling the opening of the solenoid valves 15a, 15b, it is possible to increase or decrease the amount of fuel gas supplied to the burner 3.

[0036] Also disposed within the combustion chamber 4 are an ignition plug 18 that generates a spark discharge for igniting the burner 3 by the operation of an igniter 17 (shown in FIG. 2), and a flame detection sensor 19 for detecting the presence or absence of misfire or fire in the burner 3. The flame detection sensor 19 is composed of, for example, a flame rod, a thermocouple, etc.

[0037] The convection fan 5 is disposed inside the main body case 2 facing the suction port 2a formed on the back surface of the main body case 2, and is connected to an electric motor 5a that rotates and drives the convection fan 5. By driving and rotating the convection fan 5 by the electric motor 5a, indoor air is sucked into the main body case 2 through the suction port 2a, and the sucked air passes through an air passage 2b formed in the main body case 2, and is then blown into the room from an air outlet 2c formed on the front surface of the main body case 2.

[0038] In this case, a heat exchanger 4a is disposed in the air passage 2b. Therefore, when the convection fan 5 is rotationally driven by the electric motor 5a while the burner 3 is in combustion operation, the combustion exhaust gas generated by the combustion operation of the burner 3 passes through the heat exchanger 4a and flows into the exhaust passage 11a, and heat is exchanged (transferred) from the combustion exhaust gas to the indoor air flowing through the air passage 2b. As a result, the indoor air passing through the air passage 2b is heated by the heat exchanger 4a, and the heated air is blown into the room as hot air from the air outlet 2c.

[0039] In addition, a temperature sensor 20 is arranged at the rear of the main body case 2 facing the suction port 2a to detect the temperature of the air introduced into the air passage 2b from the suction port 2a as the room temperature of the room in which the warm air heater 1 is located.

[0040] In the warm air heater 1 of this embodiment, an orifice 21 is further formed in the air supply passage 10a or the exhaust passage 11a, for example, in the air supply passage 10a on the upstream side of the combustion fan 12. This orifice 21 generates a pressure difference between the pressure on the upstream side and the pressure on the downstream side of the orifice 21 in the air supply and exhaust passage (including the combustion chamber 4 and the heat exchanger 4a) from the air supply passage 10a to the exhaust passage 11a when a normal airflow is generated by the rotational operation of the combustion fan 12.

[0041] Near the orifice 21, an upstream communication pipe 22 communicating with the intake passage 10a on the upstream side of the orifice 21 and a downstream communication pipe 23 communicating with the intake passage 10a on the downstream side of the orifice 21 are led out from the intake cylinder 10, and these upstream communication pipe 22 and downstream communication pipe 23 are connected to a pressure sensor 24 arranged outside the intake passage 10a. The pressure sensor 24 is a sensor of a known structure configured to be able to detect the differential pressure between the upstream side and downstream side of the orifice 21 (hereinafter referred to as the differential pressure before and after the orifice), and is configured, for example, by a thin film semiconductor element or the like.

[0042] As shown in FIG. 2, the hot air heater 1 further includes a controller 30 having a function of controlling the operation of the hot air heater 1, and an operation unit 40 through which a user performs operations related to the operation of the hot air heater 1.

[0043] The operation unit 40 is mounted, for example, on the surface of an exterior case (not shown) of the warm air heater 1 (an exterior case that houses the main body case 2), or on a remote control unit capable of communicating with the controller 30. Although detailed illustration is omitted, the operation unit 40 is provided with a switch for turning the warm air heater 1 on and off, a switch for setting a target room temperature (or how high or low it is), and the like.

[0044] The controller 30 is made up of one or more electronic circuit units including a processor such as a microcomputer, a memory, an interface circuit, etc., and is mounted, for example, inside an exterior case (not shown) of the hot air heater 1. Detection signals from the various sensors provided in the hot air heater 1, such as the flame detection sensor 19, temperature sensor 20, pressure sensor 24, etc., are input to this controller 30, and an operation signal from an operation unit 40 is also input thereto.

[0045] The controller 30 includes, as functions realized by the implemented hardware configuration and program (software configuration), a function as an operation control unit 31 that controls the operation of the warm air heater 1 through operation control of the electric motors 5a, 12a for driving the rotation of the convection fan 5 and the combustion fan 12, the solenoid valves 15a, 15b and the fuel adjustment valve 16 of the gas supply pipe 14, and the igniter 17 for driving the ignition plug 18, a function as a memory unit 32 that stores and holds a pre-operation pressure reference value that is a reference value of the differential pressure before and after the orifice detected by the pressure sensor 24 in a stopped state before the combustion fan 12 starts operating, and a function as an update processing unit 33 that executes processing to appropriately update the pre-operation pressure reference value stored in the memory unit 32. The operation control unit 31 corresponds to the control unit in the present invention.

[0046] Next, the operation of the hot air heater 1 of this embodiment will be described, focusing on the control processing executed by the controller 30. When an instruction to start operation of the hot air heater 1 is given by a user operating the operation unit 40 (operation to start operation of the hot air heater 1) or by a timer operation function of the hot air heater 1, the controller 30 executes the processing shown in the flowchart of FIG.

[0047] Before starting the operation of the combustion fan 12 (while the combustion fan 12 is not in operation), the controller 30 first executes the processes of STEPs 1 to 6 using the update processing unit 33. In STEP 1, the update processing unit 33 acquires the current detection value of the orifice differential pressure DP detected by the pressure sensor 24 as a pre-operation pressure detection value DP0, which is the detection value of the orifice differential pressure before the combustion fan 12 starts operating.

[0048] Next, in STEP 2, the update processing unit 33 determines a lower limit Lp1 and an upper limit Hp1 of a predetermined range for the pre-operation pressure detection value DP0 according to an average value (past average value) a1(y) of a plurality (a predetermined number) of pre-operation pressure detection values ​​acquired before the start of past operations of the combustion fan 12, in order to determine whether the pre-operation pressure detection value DP0 acquired in STEP 1 is a detection value in a state where no airflow due to outside wind is generated in the air supply / exhaust passage (windless state). The process of STEP 2 will be described in detail later.

[0049] In the next STEP 3, the update processor 33 judges whether the pre-operation pressure detection value DP0 is within a predetermined range between the lower limit value Lp1 and the upper limit value Hp1 (whether Lp1≦DP0≦Hp1) determined in STEP 2. Here, in a state where no airflow is generated in the air supply / exhaust passage due to outside wind (windless state) or in a state close to this, the judgment result in STEP 3 becomes positive.

[0050] And when the determination result in STEP3 is affirmative, in STEP4, the update processing unit 33 updates the value of the pre-operation pressure reference value A to be stored and held in the storage unit 32 according to the pre-operation pressure detection value DP0 obtained in STEP1. Specifically, the update processing unit 33 updates the pre-operation pressure reference value A by setting the pre-operation pressure detection value DP0 obtained in STEP1 as the updated value (the value after update) of the pre-operation pressure reference value A. Thereby, in a state where no airflow due to outside air is generated in the air supply and exhaust passage, or in a state close thereto, the pre-operation pressure detection value DP0 as the detection value of the differential pressure before and after the orifice detected by the pressure sensor 24 is stored and held in the storage unit 32 as the pre-operation pressure reference value A.

[0051] Next, in STEP5, the update processing unit 33 increases the value of the parameter x indicating the number of updates of the pre-operation pressure reference value A (hereinafter simply referred to as the update number x) by only "1". Further, in STEP6, the pre-operation pressure detection value DP0 (the current pre-operation pressure detection value DP0 obtained in STEP1) is stored as the value of the parameter a1(x) associated with the increased update number x in STEP5. The parameter a1(x) is a parameter for storing the set pressure detection value used for setting the lower limit value Lp1 and the upper limit value Hp1 within a predetermined range in STEP2.

[0052] On the other hand, when the determination result in STEP3 is negative (when DP0 < Lp1 or DP0 > Hp1), the pre-operation pressure detection value DP0 obtained in STEP1 is likely to be the detection value of the differential pressure before and after the orifice detected by the pressure sensor 24 in a state where airflow due to outside air is generated in the air supply and exhaust passage. Therefore, in this case, the update processing unit 33 does not execute the processing of STEP4 to STEP6 (and thus does not update the pre-operation pressure reference value A), and ends the processing before the start of operation of the combustion fan 12 for the current operation of the warm air heater 1.

[0053] Here, the processing of STEP 2, which has been explained later, will be explained. In this embodiment, the update processing unit 33 stores and holds the pre-actuation pressure detection value DP0 acquired in STEP 1 as the value of parameter a1(x) (x=1, 2, ......) every time the determination result of STEP 3 becomes positive by the processing of STEP 6 described above (in other words, every time the pre-actuation pressure reference value A is updated).

[0054] Then, in STEP 2, the update processing unit 33 calculates the past average value a1(y) of the pre-actuation pressure detection value DP0 as the average value of multiple pre-actuation pressure detection values ​​DP0 from the update of the pre-actuation pressure reference value A a predetermined number of times ago to the previous (one time before) update.

[0055] Specifically, for example, the average value of the pre-actuation pressure detection values ​​DP0 acquired at five updates of the pre-actuation pressure reference value A may be calculated as the past average value a1(y). In this case, the pre-actuation pressure detection values ​​DP0 acquired at each update from the fifth update before to the previous update (one update before) of the pre-actuation pressure reference value A are stored as the values ​​of parameters a1(x-4), a1(x-3), a1(x-2), a1(x-1), and a1(x), respectively, so that the past average value a1(y) of the pre-actuation pressure detection values ​​DP0 is calculated by the following formula (1).

[0056] a1(y)=(a1(x-4)+a1(x-3)+a1(x-2)+a1(x-1)+a1(x)) / 5 ……(1)

[0057] Then, in STEP 2, the update processing unit 33 sets a value (=a1(y)-α1) smaller than the past average value a1(y) by a predetermined value α1 as the lower limit value Lp1 of the predetermined range for the pre-actuation pressure detected value DP0, and sets a value (=a1(y)+α1) larger than the past average value a1(y) by the predetermined value α1 as the upper limit value Hp1 of the predetermined range, as shown in the following equations (2a) and (2b). As a result, the predetermined range for the pre-actuation pressure detected value DP0 is determined as a range centered on the past average value a1(y) of the pre-actuation pressure detected value DP0.

[0058] Lp1=a1(y)-α1 ……(2a) Hp1=a1(y)+α1 ……(2b)

[0059] If the number of updates of the pre-actuation pressure reference value A (the number of times the determination result in STEP 3 became positive) does not reach the predetermined number of updates (e.g., 5 times) required for calculating the past average value a1(y), for example, predetermined values ​​are set as the lower limit value Lp1 and the upper limit value Hp1 in STEP 2. Alternatively, for example, a value smaller than the current pre-actuation pressure reference value A by the predetermined value α1 (=A-α1) and a value larger than the current pre-actuation pressure reference value A by the predetermined value α1 (=A+α1) are set as the lower limit value Lp1 and the upper limit value Hp1, respectively.

[0060] Additionally, the value of the above-mentioned predetermined value α1 is set in advance based on experiments, etc. so that the judgment result in STEP 3 is positive when there is no airflow due to outside wind in the air supply and exhaust passage (windless state) or a state close to this, and the judgment result in STEP 3 is negative when an airflow generated in the air supply and exhaust passage due to outside wind causes a differential pressure before and after the orifice to act on the pressure sensor 24.

[0061] The process of the update processing unit 33 is executed as described above. After executing the process of the update processing unit 33 in STEPs 1 to 6 as described above, the controller 30 executes the processes of STEPs 7 and 8 by the operation control unit 31. In STEP 7, the operation control unit 31 controls the electric motor 12a to start the rotation operation of the combustion fan 12 (turns the combustion fan 12 ON). Although not shown in FIG. 3, in STEP 7, the operation control unit 31 further ignites the burner 3 to start the combustion operation of the burner 3, and starts the operation of the convection fan 5 via the electric motor 5a. In this case, in the ignition process of the burner 3, the operation control unit 31 controls the rotation speed of the combustion fan 12 to a predetermined rotation speed for ignition via the electric motor 12a, controls the opening of the solenoid valves 15a, 15b of the gas supply pipe 14, controls the amount of fuel gas supplied to the burner 3 to a supply amount for ignition via the fuel regulating valve 16, and generates a spark discharge in the ignition plug 18 via the igniter 17.

[0062] Furthermore, after the start of the combustion operation of the burner 3, the operation control unit 31 controls the combustion amount of the burner 3 and the rotation speed of the convection fan 5 according to the target temperature (or the degree of high or low) set by the user by operating the operation unit 40 and the room temperature detected by the temperature sensor 20, thereby causing the warm air heater 1 to perform heating operation. In this case, the combustion amount of the burner 3 is controlled through control of the rotation speed of the combustion fan 12 (control of the supply amount of combustion air) and control of the fuel regulating valve 16 (control of the supply amount of fuel gas).

[0063] Then, the operation control unit 31 executes the process of STEP 8 while the combustion fan 12 is operating. In this STEP 8, the operation control unit 31 executes a process of determining the degree of blockage of the supply and exhaust passage from the air supply passage 10a to the exhaust passage 11a based on the amount of pressure change that is the difference between the operation pressure detection value and the pre-operation pressure reference value A (=operation pressure detection value-A) while sequentially acquiring the operation pressure detection value that is the orifice front-rear pressure differential DP detected by the pressure sensor 24.

[0064] Specifically, in this embodiment, the operation control unit 31 successively determines whether the pressure change amount becomes smaller than a predetermined threshold value. Here, when the blockage of the supply and exhaust passage progresses to a certain extent (when the degree of blockage increases), the air volume in the supply and exhaust passage decreases, and the pressure change amount becomes smaller than the predetermined threshold value. In this case, since an appropriate amount of combustion air cannot be supplied to the burner 3, the operation control unit 31 closes one or both of the solenoid valves 15a and 15b to forcibly stop the combustion operation of the burner 3. Furthermore, the operation control unit 31 outputs error information indicating that the degree of blockage of the supply and exhaust passage is high via a display (not shown) of the warm air heater 1.

[0065] In this embodiment, the processing of the update processing unit 33 is executed as described above, so that it is possible to prevent the pre-operation pressure reference value A from being updated using the pre-operation pressure detection value DP0 in a state where the combustion fan 12 is stopped before it starts operating and an airflow due to outside wind is generated in the supply and exhaust passage (and thus the differential pressure before and after the orifice detected by the pressure sensor 24 is affected by the airflow).

[0066] Then, in a stopped state before the combustion fan 12 starts operating, when there is no airflow due to outside wind in the air supply and exhaust duct (windless state) or a state close to this, the pre-operation pressure reference value A is updated using the pre-operation pressure detection value DP0.

[0067] Therefore, the pre-operation pressure reference value A, which is highly reliable as a value equivalent to the detection value of the pressure difference across the orifice when there is no wind in the supply and exhaust passage, can be stored and held in the memory unit 32. Furthermore, the pressure change amount while the combustion fan 12 is operating has high reliability as an index value corresponding to the degree of blockage and air volume of the supply and exhaust passage.

[0068] Therefore, when the degree of blockage of the supply and exhaust passage is high (and thus when an appropriate amount of combustion air cannot be supplied to the burner 3), the combustion operation of the burner 3 can be stopped at an appropriate timing. Also, it is possible to prevent the combustion operation of the burner 3 from being stopped due to an erroneous detection that the degree of blockage of the supply and exhaust passage is high, when the degree is sufficiently low.

[0069] In addition, in this embodiment, since the lower limit value Lp1 and the upper limit value Hp1 of the predetermined range to be compared with the pre-activation pressure detection value DP0 in STEP 3 are set as described above, it is possible to appropriately set the predetermined range suitable for the pre-activation pressure detection value DP0 including the influence of the drift even if a steady drift occurs in the output of the pressure sensor 24. As a result, it is possible to prevent the occurrence of a situation in which the determination result in STEP 3 becomes negative even when there is no wind in the supply and exhaust passage.

[0070] Then, by updating the pre-actuation pressure reference value A when the pre-actuation pressure detection value DP0 falls within the specified range, an appropriate pre-actuation pressure reference value A can be stored and maintained in the memory unit 32 for the pressure sensor 24 that has experienced steady drift.

[0071] [Second embodiment] Next, a second embodiment of the present invention will be described with reference to Fig. 4. Note that this embodiment differs from the first embodiment only in the processing of the update processing unit 33 of the controller 30, and therefore a description of the same matters as in the first embodiment will be omitted.

[0072] In this embodiment, when the user operates the operating unit 40 (operation to start the operation of the hot air heater 1) or when the timer operation function of the hot air heater 1 instructs the controller 30 to start operation, the controller 30 executes the processing shown in the flowchart of Figure 4.

[0073] Before starting the operation of the combustion fan 12 (while the combustion fan 12 is not in operation), the controller 30 first executes the processes of STEPs 11 to 20 using the update processing unit 33. In STEP 11, the update processing unit 33 acquires the current detection value of the pressure difference across the orifice detected by the pressure sensor 24 as a pre-operation pressure detection value DP0, which is the detection value of the pressure difference across the orifice before the combustion fan 12 starts operating.

[0074] Next, in STEP 12, the update processing unit 33 determines a lower limit value Lp2 and an upper limit value Hp2 of a predetermined range for the pre-actuation pressure detection value DP0 in accordance with the current pre-actuation pressure reference value A to determine whether the pre-actuation pressure detection value DP0 is close to the current pre-actuation pressure reference value A.

[0075] In this case, as shown in the following equations (3a) and (3b), the update processing unit 33 sets a value (=A-α2) that is smaller than the current pre-actuation pressure reference value A by a predetermined value α2 as the lower limit value Lp2 of the predetermined range for the pre-actuation pressure detected value DP0, and sets a value (=A+α2) that is larger than the current pre-actuation pressure reference value A by the above-mentioned predetermined value α2 as the upper limit value Hp2 of the predetermined range. As a result, the predetermined range for the pre-actuation pressure detected value DP0 is determined as a range centered on the current pre-actuation pressure reference value A.

[0076] Lp2=A-α2 ……(3a) Hp2=A+α2 ……(3b)

[0077] In the next STEP 13, the update processor 33 judges whether the pre-operation pressure detection value DP0 is within a predetermined range between the lower limit value Lp2 and the upper limit value Hp2 (whether Lp2≦DP0≦Hp2). If there is no airflow in the air supply / exhaust passage due to outside wind, or a state close to this, and there is no drift in the output of the pressure sensor 24 due to deterioration of the pressure sensor 24, or if the drift is sufficiently small, the judgment result in STEP 13 becomes positive (the value of the above-mentioned predetermined value α2 is set in advance based on experiments, etc., so that this is the case).

[0078] If the judgment result in STEP 13 is positive, the current pre-operation pressure reference value A can be deemed to match or nearly match the value of the differential pressure before and after the orifice detected by the pressure sensor 24 in a state where no airflow due to outside wind is occurring in the supply and exhaust path (windless state) or in a state close to this.

[0079] In this case, the update processing unit 33 initializes the count value n to zero in STEP 14 without updating the pre-operation pressure reference value A, and ends the processing before the start of the current operation of the combustion fan 12. The count value n is a parameter for counting the number of consecutive times that the determination result in STEP 13 becomes negative.

[0080] Situations in which the judgment result of STEP 13 will be negative include a situation in which a steady drift in the output of pressure sensor 24 has occurred, causing the current pre-activation pressure reference value A to deviate from the detection value of the differential pressure before and after the orifice detected by pressure sensor 24 (the detection value indicated by the output of pressure sensor 24 including the effects of drift) in a state in which no airflow due to outside wind is occurring in the air intake passage 10a or exhaust passage 11a (windless state) or in a state close to this, or a situation in which the pre-activation pressure detection value DP0 has become a value that deviates from the pre-activation pressure reference value A due to the temporary occurrence of an airflow due to outside wind in the air intake passage 10a or exhaust passage 11a.

[0081] Therefore, when the determination result in STEP13 is negative (when DP0 < Lp1 or DP0 > Hp1), the update processing unit 33 executes the processing from STEP15. In STEP15, the update processing unit 33 increases the count value n by "1", and further, in STEP16, the current pre-operation pressure detection value DP0 (the pre-operation pressure detection value DP0 obtained in STEP1) is stored as the value of the parameter a2(n) associated with the count value n. As a result, when the determination result in STEP13 continuously becomes negative repeatedly, each pre-operation pressure detection value DP0 is sequentially stored as the values of the parameters a2(1), a3(2),.... The pre-operation pressure detection value DP0 stored as the values of the parameters a2(1), a3(2),.... in this way is the update pressure detection value used to update the pre-operation pressure reference value A.

[0082] Next, in STEP17, the update processing unit 33 determines whether the current count value n has reached a predetermined number N (for example, N = 5). That is, it is determined whether the number of times the determination result in STEP13 has continuously become negative has reached the predetermined number N.

[0083] Here, in a situation where the determination result in STEP13 becomes negative due to a temporary airflow caused by outside air in the air supply and exhaust passage, generally, the determination result in STEP17 becomes negative. In this case, the update processing unit 33 ends the processing before the start of the current operation of the combustion fan 12 without updating the pre-operation pressure reference value A.

[0084] On the other hand, due to a steady drift in the output of the pressure sensor 24, when the current pre-operation pressure reference value A deviates from the detection value of the differential pressure before and after the orifice detected by the pressure sensor 24 (the detection value indicated by the output of the pressure sensor 24 including the influence of the drift) in a state where no airflow is generated by outside air in the air supply passage 10a or the exhaust passage 11a (windless state) or a state close to this, the determination result in STEP13 becomes negative continuously repeatedly immediately before the start of each operation of the warm air heater 1 (immediately before the operation start of the combustion fan 12). As a result, the determination result in STEP17 becomes positive.

[0085] In this case, each time the determination result in STEP 13 becomes negative, the update processing unit 33 executes in STEP 18 the calculation of the average value a2(y) from the values ​​of the predetermined number N of parameters a2(1), a2(2), ..., a2(N) set in STEP 16. The average value a2(y) is calculated by the following formula (4).

[0086] a2(y)=(a2(1)+a2(2)+ … +a2(N)) / N …(4)

[0087] Next, in STEP 19, the update processing unit 33 updates the value of the pre-actuation pressure reference value A stored in the memory unit 32 in accordance with the average value a2(y). Specifically, the update processing unit 33 updates the pre-actuation pressure reference value A by setting the average value a2(y) as an update value (updated value) of the pre-actuation pressure reference value A. As a result, when the result of the determination in STEP 13 becomes negative a predetermined number of times (=predetermined number N), the average value a2(y) of the pre-actuation pressure detection value DP0 as the detection value of the differential pressure before and after the orifice detected by the pressure sensor 24 before the start of operation of the combustion fan 12 each time is stored in the memory unit 32 as the pre-actuation pressure reference value A.

[0088] Next, in STEP 20, the update processing unit 33 initializes the count value n to zero, and ends the processing before the start of the current operation of the combustion fan 12.

[0089] After the controller 30 executes the processes of the update processing unit 33 in STEPs 11 to 20 as described above, the operation control unit 31 executes the processes of STEPs 21 and 22. The processes of STEPs 21 and 22 are the same as the processes of STEPs 7 and 8 in the first embodiment. The combustion operation of the burner 3 is also performed in the same manner as in the first embodiment.

[0090] In this embodiment, the processing of the update processing unit 33 is executed as described above, so that it is possible to prevent the pre-operation pressure reference value A from being updated using the pre-operation pressure detection value DP0 in a state where the combustion fan 12 is stopped before it starts operating and an airflow due to outside wind is generated in the supply and exhaust passage (and thus the differential pressure before and after the orifice detected by the pressure sensor 24 is affected by the airflow).

[0091] Then, when the pre-operation pressure detection value DP0 in a stopped state before the combustion fan 12 starts operating and in a state where no airflow due to outside wind is generated in the supply and exhaust duct (windless state) or a state close to this, results in a positive judgment in STEP 13 due to the occurrence of a steady drift (non-insignificant drift) in the output of the pressure sensor 24, the pre-operation pressure reference value A is updated using the average value of multiple pre-operation pressure detection values ​​DP0.

[0092] Therefore, the pre-operation pressure reference value A, which is highly reliable as a value equivalent to the detection value of the pressure difference across the orifice when there is no wind in the supply and exhaust passage, can be stored and held in the memory unit 32. Furthermore, the pressure change amount while the combustion fan 12 is operating has high reliability as an index value corresponding to the degree of blockage and air volume of the supply and exhaust passage.

[0093] Therefore, when the degree of blockage of the supply and exhaust passage is high (and thus when an appropriate amount of combustion air cannot be supplied to the burner 3), the combustion operation of the burner 3 can be stopped at an appropriate timing. Also, it is possible to prevent the combustion operation of the burner 3 from being stopped due to an erroneous detection that the degree of blockage of the supply and exhaust passage is high, when the degree is sufficiently low.

[0094] Furthermore, in this embodiment, the pre-actuation pressure reference value A is updated to appropriately reflect the influence caused by the steady drift of the output of the pressure sensor 24, so that by setting the lower limit value Lp2 and the upper limit value Hp2 of the predetermined range to be compared with the pre-actuation pressure detection value DP0 in STEP 13 as described above, it is possible to set a predetermined range suitable for the pre-actuation pressure detection value DP0 including the influence of the drift of the output of the pressure sensor 24. Furthermore, it is possible to prevent the determination result in STEP 13 from frequently becoming negative due to the influence of a breeze occurring in the supply and exhaust passage, and to prevent unnecessary updating of the pre-actuation pressure reference value A.

[0095] In this embodiment, if the judgment result in STEP 13 is positive, the pre-actuation pressure reference value A is not updated. However, if the judgment result in STEP 13 is positive, the pre-actuation pressure reference value A may be updated, for example, in the same manner as in the processing in STEP 4 of the first embodiment.

[0096] [Other embodiments] The present invention is not limited to the first and second embodiments, and other embodiments may be adopted. Some of the other embodiments are exemplified below.

[0097] In each of the above-mentioned embodiments, when the pressure change amount (= pressure detection value during operation - A) during operation of the combustion fan 12 is smaller than a predetermined threshold, the combustion operation of the burner 3 is stopped. However, for example, the degree of blockage of the supply and exhaust passage may be estimated from the pressure change amount during operation of the combustion fan 12, and the combustion operation of the burner 3 may be stopped when the estimated value of the blockage degree exceeds a predetermined threshold. Alternatively, the air volume of the supply and exhaust passage may be estimated from the pressure change amount during operation of the combustion fan 12, and the combustion operation of the burner 3 may be stopped when the estimated value of the air volume becomes smaller than a predetermined threshold.

[0098] Furthermore, for example, by appropriately correcting the rotation speed of the combustion fan 12 from the rotation speed when the supply and exhaust passage is normal depending on the amount of pressure change, or the degree of blockage of the supply and exhaust passage estimated from the amount of pressure change, or the air volume of the supply and exhaust passage estimated from the amount of pressure change, it is possible to supply an appropriate amount of combustion air to the burner 3 while continuing the combustion operation of the burner 3 even if the degree of blockage of the supply and exhaust passage becomes relatively high.

[0099] Further, in each of the above-described embodiments, the pressure sensor 24 is provided on the intake air passage 10a side, but the pressure sensor 24 may be provided on the exhaust air passage 11a side.

[0100] In addition, in the first embodiment, when the judgment result of STEP 3 is positive, the pre-operation pressure reference value A is updated to the pre-operation pressure detection value DP0 obtained in the immediately preceding STEP 1. However, for example, the average value of the pre-operation pressure detection values ​​DP0 obtained before the combustion fan 12 starts operating multiple times (including the pre-operation pressure detection value DP0 obtained before the combustion fan 12 starts operating this time) may be set as the updated value of the pre-operation pressure reference value A.

[0101] In addition, in each of the above embodiments, a hot air heater 1 is exemplified as a forced air supply and exhaust type combustion device, but the forced air supply and exhaust type combustion device of the present invention is not limited to a hot air heater and may be, for example, a combustion device provided in a heat source unit of a hot water supply device. [Explanation of symbols]

[0102] 1...hot air heater (forced intake and exhaust combustion device), 3...burner, 10a...air intake passage, 11a...exhaust passage, 12...combustion fan (blower), 21...orifice, 24...pressure sensor, 31...operation control unit (control unit), 32...memory unit, 33...update processing unit.

Claims

1. A forced intake and exhaust type combustion device that supplies combustion air to a burner through an air intake path by operating a blower, and exhausts combustion exhaust gas generated by the combustion operation of the burner through an exhaust path, a pressure sensor for detecting a differential pressure between an upstream side and a downstream side of an orifice provided in the air supply passage or the exhaust passage; a storage unit that stores and holds a pre-operation pressure reference value that is a reference value of the pressure value detected by the pressure sensor in a stopped state before the blower starts operating; a control unit which acquires an operating pressure detection value, which is a pressure value detected by the pressure sensor during operation of the blower, and controls operation of the burner in accordance with a pressure change amount, which is a difference between the operating pressure detection value and the stored pre-operation pressure reference value, or in accordance with a degree of blockage of the air supply passage or the exhaust passage estimated from the pressure change amount, or in accordance with an air volume of the air supply passage or the exhaust passage estimated from the pressure change amount; an update processing unit that executes a process of updating the pre-operation pressure reference value stored and held in the storage unit, a pre-operation pressure detection value obtained by the pressure sensor in a stopped state before the blower starts operating, and determining whether the pre-operation pressure detection value is within a predetermined range; if the pre-operation pressure detection value is not within the predetermined range, the pre-operation pressure reference value stored and held in the memory unit is not updated; if the pre-operation pressure detection value is within the predetermined range, the pre-operation pressure reference value stored and held in the memory unit is updated in accordance with at least the pre-operation pressure detection value; and when the pre-operation pressure detection value is within the predetermined range, the pre-operation pressure detection value is stored as a setting pressure detection value for newly setting the predetermined range, and the predetermined range to be compared with the pre-operation pressure detection value obtained in a stopped state before the blower starts operating is set to a range centered on an average value of multiple setting pressure detection values ​​stored in the past.

2. 2. The forced intake and exhaust combustion apparatus according to claim 1, The forced intake and exhaust combustion device is characterized in that the update processing unit is configured to update the pre-operation pressure reference value to the pre-operation pressure detection value when updating the pre-operation pressure reference value stored and held in the memory unit.

3. A forced intake and exhaust type combustion device that supplies combustion air to a burner through an air intake path by operating a blower, and exhausts combustion exhaust gas generated by the combustion operation of the burner through an exhaust path, a pressure sensor for detecting a differential pressure between an upstream side and a downstream side of an orifice provided in the air supply passage or the exhaust passage; a storage unit that stores and holds a pre-operation pressure reference value that is a reference value of the pressure value detected by the pressure sensor in a stopped state before the blower starts operating; a control unit which acquires an operating pressure detection value, which is a pressure value detected by the pressure sensor during operation of the blower, and controls operation of the burner in accordance with a pressure change amount, which is a difference between the operating pressure detection value and the stored pre-operation pressure reference value, or in accordance with a degree of blockage of the air supply passage or the exhaust passage estimated from the pressure change amount, or in accordance with an air volume of the air supply passage or the exhaust passage estimated from the pressure change amount; an update processing unit that executes a process of updating the pre-operation pressure reference value stored and held in the storage unit, The forced intake and exhaust combustion apparatus is characterized in that the update processing unit is configured to acquire a pre-operation pressure detection value, which is the pressure value detected by the pressure sensor in a stopped state before the blower starts operating, determine whether the pre-operation pressure detection value is within a predetermined range, and if the pre-operation pressure detection value is not within the predetermined range, count the number of consecutive occurrences of the event that the pre-operation pressure detection value is not within the predetermined range, and when the counted number reaches a predetermined number, update the pre-operation pressure reference value stored and held in the memory unit at least in accordance with the pre-operation pressure detection value, and when the counted number does not meet the predetermined number, not update the pre-operation pressure reference value stored and held in the memory unit.

4. 4. The forced intake and exhaust type combustion apparatus according to claim 3, A forced intake and exhaust combustion device characterized in that the update processing unit is configured to set the specified range to a range centered on a pre-operation pressure reference value stored and held in the memory unit.

5. The forced intake and exhaust type combustion apparatus according to claim 3 or 4, The forced intake and exhaust combustion device is characterized in that the update processing unit is configured to store the pre-operation pressure detection value as an update pressure detection value for updating the pre-operation pressure reference value when the pre-operation pressure detection value is not within a predetermined range, and is configured to update the pre-operation pressure reference value stored in the memory unit when the counted number reaches the predetermined number, to an average value of the pre-operation pressure detection values ​​stored at each of the predetermined number of times.

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