JP2021099205A - Water heater - Google Patents

Abstract

To solve a problem that when a burner is ignited, fixation of a butterfly valve prevents normal operation and ignition delay occurs.SOLUTION: In a water heater, a controller can switch combustion amount of a burner between two large and small stages by opening/closing a butterfly valve 10 provided in a mixing cylinder 40 of a premixer 7. The controller sets a waiting position C where the butterfly valve 10 is waited before ignition of the burner at an intermediate position between a valve opening position A and a valve closing position B of the butterfly valve 10, and moves the butterfly valve 10 from the waiting position C to the valve opening position A or the valve closing position B in accordance with the combustion amount when the burner is ignited.SELECTED DRAWING: Figure 2

Description

The present invention relates to a water heater including a premixer that generates a mixture of fuel gas and combustion air by rotating a fan.

As disclosed in Patent Document 1, a water heater is known to be provided with a premixer on the upstream side of a burner to generate an air-fuel mixture of fuel gas and combustion air by rotating a fan. .. In this premixer, fuel gas and combustion air are branched into two Venturi supplies, and the controller opens and closes the butterfly valve to open and close one Venturi to burn the burner. The amount can be switched between large and small.

U.S. Patent Application Publication 2011/139045

In the butterfly valve, the seal portion is brought into close contact with the valve seat to block the flow path, so that the butterfly valve may stick to the valve seat if the valve is closed for a long time. Therefore, when the burner is ignited in two stages (large side) with the butterfly valve standing by in the closed position, the butterfly valve may not normally operate to the valve opening side.
In order to avoid this sticking, it is conceivable to make the butterfly valve stand by at the valve opening position, but if the burner is ignited in one stage (small side) with the butterfly valve standing by at the valve opening position, the timing of valve closing May be delayed and ignition may be delayed, resulting in deterioration of hot water discharge characteristics.

Therefore, an object of the present invention is to provide a water heater in which the butterfly valve does not stick when the burner is ignited and does not operate normally or cause an ignition delay regardless of the combustion stage of the burner. It was done.

In order to achieve the above object, the invention according to claim 1 is a premixer for generating an air-fuel mixture mixed with fuel gas through a fan and supplying the burner, and operating the fan and the burner. Equipped with a controller to control the combustion of
The premixer includes two venturis in which air flows by the rotation of a fan and fuel gas is supplied through a branch pipe branched from a gas supply path, and a butterfly valve that can open and close one venturi. ,
The controller is a water heater that can switch the combustion amount of the burner in two stages, large and small, by opening and closing the butterfly valve.
The controller sets a standby position between the valve opening position and the valve closing position of the butterfly valve to make the butterfly valve stand by before ignition of the burner, and when the burner is ignited, the butterfly valve is set to the standby position according to the amount of combustion. It is characterized by moving from the valve to the valve opening position or the valve closing position.

According to the first aspect of the present invention, since the butterfly valve is moved from the standby position to the valve open position or the valve closed position, the butterfly valve is fixed at the time of ignition of the burner and operates normally regardless of the combustion stage of the burner. It will not be done or cause ignition delay.

It is a schematic diagram of a water heater. It is a vertical sectional view of a mixing cylinder.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an example of a water heater. In this water heater 1, a burner 3 is arranged on the upper side of the combustion chamber 2 with the combustion surface facing downward, and a primary heat exchanger 4 that mainly recovers the apparent heat of the combustion exhaust is placed on the lower side of the burner 3. It is a reverse combustion type in which a secondary heat exchanger 5 for recovering latent heat is arranged. The burner 3 is a mesh burner provided with a flame hole plate having a large number of flame holes formed on the lower surface.
A premixer 7 is provided on the upstream side of the gas supply pipe 6 to the burner 3. The premixer 7 includes a fan 8 on the downstream side and two Venturi 9A and 9B on the upstream side. The Venturi 9B is opened and closed by the butterfly valve 10. Air suction ports 11A and 11B are provided on the upstream side of the Venturi 9A and 9B, respectively.
Branch pipes 12A and 12B branching from the gas supply pipe 6 are connected to the downstream side of the suction ports 11A and 11B in the Venturi 9A and 9B, respectively. The branch pipe 12B is provided with a solenoid valve 13 that opens and closes a gas flow path to the venturi 9B. A pressure equalizing valve 14 is provided on the upstream side of the branch pipes 12A and 12B in the gas supply pipe 6.

A water supply pipe 15 is connected to the inlet end of the secondary heat exchanger 5, and the outlet end of the secondary heat exchanger 5 is connected to the inlet end of the primary heat exchanger 4. A hot water pipe 16 is connected to the outlet side end of the primary heat exchanger 4. A bypass pipe 17 is connected between the water supply pipe 15 and the hot water outlet pipe 16 outside the combustion chamber 2.
The water supply pipe 15 is provided with a water amount sensor 18, a water entry temperature sensor 19, and a water amount adjusting valve 20. The hot water outlet pipe 16 is provided with an outlet temperature sensor 21 that detects the temperature near the outlet from the primary heat exchanger 4 and a hot water outlet temperature sensor 22 that detects the temperature downstream from the connection portion with the bypass pipe 17. .. The bypass pipe 17 is provided with a bypass valve 23 for adjusting the bypass flow rate.

A drain discharge pipe 24 provided with a neutralizer 25 is connected to the combustion chamber 2. Further, an exhaust duct 26 is connected to the combustion chamber 2 to open the downstream end to the outside. Further, the combustion chamber 2 is provided with an igniter 27 for igniting the burner 3 and a frame rod 28 for detecting flames.
The water heater 1 is a controller that controls the combustion of the burner 3 and the rotation of the fan 8 based on the detection signals obtained from each sensor, and executes the hot water temperature control that matches the hot water temperature with the set temperature set by the remote controller 31. It has 30.

The premixer 7 includes a fan case (not shown) for accommodating the fan 8 and a mixing cylinder attached to the lower part of the fan case. FIG. 2 shows the details of the mixing cylinder 40. The mixing cylinder 40 is coaxially connected to the lower cylinder portion 41 that opens the air suction ports 11A and 11B at the lower end and the upper end of the lower cylinder portion 41, and the diameter increases as the diameter increases as it goes upward. It has a part 42 and. In the lower cylinder portion 41, a decompression portion 43 having a small passage area through which air sucked from the suction ports 11A and 11B passes is formed.
In the mixing cylinder 40, a partition wall 44 in the vertical direction is formed from the lower cylinder portion 41 to the decompression portion 43 and the lower portion of the upper cylinder portion 42, and the inside of the mixing cylinder 40 is divided into left and right. However, the partition wall 44 is arranged at a position eccentric to one side from the axial center of the mixing cylinder 40, and the Venturi 9A that vertically penetrates the left side of the partition wall 44 in FIG. 2 and the partition wall 44 in the mixing cylinder 40. It forms a Venturi 9B that penetrates up and down on the right side of the.

Further, a butterfly valve 10 is provided on the upper side of the partition wall 44 in the upper cylinder portion 42. The butterfly valve 10 is a semicircular plate having a seal plate 45 fixed to the back surface, and support portions 46, 46 provided at both front and rear ends of the lower end are rotatably held on the upper side of the partition wall 44. On the venturi 9B side of the upper cylinder portion 42, a U-shaped valve seat 47 that inclines upward from the upper end of the partition wall 44 to the right side is formed.
A valve drive motor (not shown), which is a stepping motor, is provided on the back surface of the mixing cylinder 40, and a motor shaft (not shown) is connected to a support portion 46 on the rear side. Therefore, due to the rotation of the valve drive motor, the butterfly valve 10 stands up on the extension to the upper side of the partition wall 44 as shown by the solid line in FIG. 2, and is shown by the valve opening position A for opening the venturi 9B and the alternate long and short dash line. As described above, the seal plate 45 is tilted until it comes into contact with the valve seat 47 so that it can swing with the valve closing position B that closes the venturi 9B.

However, the butterfly valve 10 before ignition of the burner 3 is made to stand by by the valve drive motor at the standby position C which is intermediate between the valve opening position A and the valve closing position B, as also indicated by the alternate long and short dash line. ing. The standby position C is also a position (solenoid valve opening / closing position) in which the solenoid valve 13 is opened / closed when the burner 3 switches the combustion stage during combustion.
Then, in the mixing cylinder 40, between the upper end of the lower cylinder portion 41 and the upper end of the decompression portion 43, communication passages 48A and 48B that communicate with the branch pipes 12A and 12B and open to the upper cylinder portion 42 side are formed. Has been done.

When water is passed through the water heater 1 configured as described above, the controller 30 drives the fan motor to rotate the fan 8 at a rotation speed corresponding to the amount of combustion required by the remote controller 31. At this time, if the combustion amount is equal to or more than a predetermined threshold value, it is assumed that the ignition is in two stages (large side combustion amount), the solenoid valve 13 is opened, the valve drive motor is controlled, and the butterfly valve 10 is on standby. The venturi 9B is opened by moving from the position C to the valve opening position A. Since the butterfly valve 10 is not located at the valve closing position B, it can smoothly move to the valve opening position A without sticking.
Then, in the mixing cylinder 40, air proportional to the rotation speed of the fan 8 is sucked from below the lower cylinder portion 41 from the suction ports 11A and 11B, and flows on the left side of the partition wall 44 as shown by the dotted arrow in FIG. It branches into air A1 and air A2 flowing on the right side, and flows to the upper cylinder portion 42 through the venturis 9A and 9B, respectively. At this time, the air A1 and A2 passing through the venturis 9A and 9B increase the flow velocity and flow to the upper cylinder portion 42 due to the reduction of the passage area of the pressure reducing portion 43, so that a negative pressure is generated.

At the same time, in the gas supply pipe 6, a main valve (not shown) is opened to supply fuel gas, which branches to the branch pipes 12A and 12B through the pressure equalizing valve 14 and flows. Therefore, as shown by the solid line in FIG. 2, gas G1 and G2 in an amount corresponding to the difference pressure from the negative pressure generated in the venturis 9A and 9B are sucked into the upper cylinder portion 42 from the communication passages 48A and 48B. Here, it is mixed with air A1 and A2 to generate an air-fuel mixture.

On the other hand, when the required combustion amount is less than a predetermined threshold value, it is assumed that the ignition is in the first stage (smaller combustion amount), and the valve drive motor is controlled to move the butterfly valve 10 from the standby position C to the valve closing position B. And block the Venturi 9B. Since the butterfly valve 10 is not located at the valve opening position A, it can be quickly moved to the valve closing position B.
Therefore, the air sucked by the fan 8 is only the air A1 passing through the venturi 9A. Further, the fuel gas flows from only the branch pipe 12A into the communication passage 48A.
Then, from the communication passage 48A, a gas G1 in an amount corresponding to the differential pressure from the negative pressure generated in the Venturi 9A is sucked into the upper cylinder portion 42, where the gas G1 is mixed with the air A1 to generate an air-fuel mixture.

The air-fuel mixture thus generated in the mixing cylinder 40 is sucked into the fan case, sent to the burner 3, ejected from each flame hole of the flame hole plate, ignited by the igniter 27, and burned.
The combustion exhaust from the burner 3 passes between the fins of the primary heat exchanger 4 to exchange heat with the water flowing in the heat transfer tube, and the sensible heat is recovered. After that, by passing through the secondary heat exchanger 5, heat is exchanged with the water flowing in the internal flow path, and the latent heat is recovered. Then, it rises in the exhaust duct 26 and is discharged to the outside.
After that, the controller 30 controls the rotation speed of the fan 8 and the switching control of the combustion stage of the burner 3 based on the difference between the hot water temperature obtained from the hot water temperature sensor 22 and the set temperature set by the remote controller 31. ..

Here, when switching the combustion stage of the burner 3 from the first stage to the second stage, the controller 30 controls the valve drive motor to move the butterfly valve 10 from the valve closing position B to the valve opening position A to move the venturi 9B. Open. At this time, the controller 30 opens the solenoid valve 13 at the timing when the butterfly valve 10 passes through the standby position C between the valve opening position A and the valve closing position B. This timing can be grasped from the pulse signal that controls the valve drive motor.
On the other hand, when switching the combustion stage of the burner 3 from the second stage to the first stage, the controller 30 controls the valve drive motor to move the butterfly valve 10 from the valve opening position A to the valve closing position B to close the venturi 9B. To do. At this time as well, the controller 30 closes the solenoid valve 13 at the timing when the butterfly valve 10 passes the standby position C. This timing can also be grasped from the pulse signal that controls the valve drive motor.
In this way, since the solenoid valve 13 opens and closes at the timing when the butterfly valve 10 passes through the standby position C, the timing at which the air and the fuel gas are supplied does not deviate significantly, and so-called air richness and gas richness are less likely to occur.

As described above, according to the water heater 1 of the above-described embodiment, the controller 30 has a standby position in which the butterfly valve 10 stands by between the valve opening position A and the valve closing position B of the butterfly valve 10 before the burner 3 is ignited. C is set so that when the burner 3 is ignited, the butterfly valve 10 is moved from the standby position C to the valve opening position A or the valve closing position B according to the amount of combustion.
With this configuration, regardless of the combustion stage of the burner 3, the butterfly valve 10 does not stick when the burner 3 is ignited and does not operate normally or causes an ignition delay.

In addition, the controller 30 sets a standby position C (solenoid valve opening / closing position) for opening / closing the solenoid valve 13 between the valve opening position A and the valve closing position B of the butterfly valve 10, and opens / closes the butterfly valve 10. When operating, the solenoid valve 13 is opened and closed at the timing when the butterfly valve 10 passes the standby position C.
With this configuration, air richness and gas richness are less likely to occur, and deterioration of the combustion state when switching the combustion stage of the burner 3 can be prevented.

In the above embodiment, the standby position (solenoid valve opening / closing position) of the butterfly valve is set between the valve opening position and the valve closing position, but it does not have to be in the exact middle position, and the valve opening position and the valve closing position do not have to be strictly intermediate. The standby position (solenoid valve opening / closing position) may be set at a position close to either of the positions.
Further, the valve closing side of the butterfly valve may be the opposite side (left side in FIG. 2). In this case, the solenoid valve is also provided in the branch pipe on the closed side.
Further, the present invention can be applied to a water heater in which the premixer is located on the downstream side of the fan.
In addition, the present invention is applicable not only to the reverse combustion type but also to a water heater in which a primary heat exchanger and a secondary heat exchanger are installed on the upper side of the burner and a water heater without a secondary heat exchanger. It is possible.

1 ... Water heater, 2 ... Combustion chamber, 3 ... Burner, 4 ... Primary heat exchanger, 5 ... Secondary heat exchanger, 6 ... Gas supply pipe, 7 ... Premixer, 8 ...・ Fan, 9A, 9B ・ ・ Ventury, 10 ・ ・ Butterfly valve, 11A, 11B ・ ・ Suction port, 12A, 12B ・ ・ Branch pipe, 13 ・ ・ Electromagnetic valve, 15 ・ ・ Water supply pipe, 16 ・ ・ Hot water pipe, 17 ... Bypass pipe, 18 ... Water volume sensor, 19 ... Water inlet temperature sensor, 21 ... Outlet temperature sensor, 22 ... Hot water temperature sensor, 26 ... Exhaust duct, 30 ... Controller, 31 ... Remote control, 40・ ・ Mixing cylinder, 41 ・ ・ Lower cylinder part, 42 ・ ・ Upper cylinder part, 44 ・ ・ Partition wall, 48A, 48B ・ ・ Continuous passage.

Claims (1)

A premixer for generating an air-fuel mixture mixed with fuel gas through a fan and supplying the mixture to the burner, and a controller for controlling the operation of the fan and the combustion of the burner are provided.
The premixer includes two venturis in which air flows by the rotation of the fan and fuel gas is supplied through a branch pipe branched from the gas supply path.
Includes a butterfly valve capable of opening and closing one of the venturis.
The controller is a water heater that can switch the combustion amount of the burner in two stages, large and small, by opening and closing the butterfly valve.
The controller sets a standby position for the butterfly valve to stand by before ignition of the burner between the valve opening position and the valve closing position of the butterfly valve, and when the burner is ignited, it corresponds to the combustion amount. A water heater characterized in that the butterfly valve is moved from the standby position to the valve opening position or the valve closing position.

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