Hot Water Apparatus

This application claims the priority benefits of Japanese application no. 2024-060684, filed on Apr. 4, 2024. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

The disclosure relates to a hot water apparatus such as a hot water supply apparatus.

Patent Literature 1 (Japanese Patent No. 3674014) describes a hot water apparatus as a specific example.

The hot water apparatus described in this literature includes a heat exchanger capable of heating hot water using a burner, and a water inlet passage and a hot water outlet passage respectively connected to the inlet side and the outlet side of this heat exchanger are connected to each other via a bypass passage. This allows heated hot water heated by the heat exchanger to flow through the hot water outlet passage while mixing unheated bypass hot water flowing through the bypass passage with this heated hot water. The respective flow rates of the heated hot water and bypass hot water can be changed using, for example, two flow control valves (heat exchanger flow control valve, bypass flow control valve), thereby setting the temperature of the mixed hot water to or bringing the temperature close to a desired target hot water supply temperature.

On the other hand, in the aforementioned hot water apparatus, when there is output of abnormally high-temperature hot water, in which hot water at a predetermined high temperature or above is output from the hot water outlet to the exterior, or there is such a risk, this is detected by a predetermined means. In addition, when this is detected, both the two flow control valves are fully closed, and the flow of hot water is blocked, which appropriately suppresses the occurrence of output of abnormally high-temperature hot water.

However, in the aforementioned related technology, there are issues to be resolved, as described below.

That is, there are valve devices described in Patent Literatures 2 and 3 (Japanese Patent No. 5004674 and Japanese Patent No. 3812614) as specific examples of valve devices, and in some cases, it may be desired to use such valve devices in place of the two flow control valves in the aforementioned hot water apparatus. More specifically, the valve devices described in Patent Literatures 2 and 3 are so-called three-way valves, and it is possible to use such a valve device as a mixing valve that enables heated hot water heated by the heat exchanger and unheated bypass hot water to flow into the first and second ports of this valve device, and enables the mixed hot water to flow out from the third port. In this case, it is possible to sequentially execute flow rate control in a temperature adjustment range mode, in which the flow rate of heated hot water gradually increases while the flow rate of bypass hot water gradually decreases, and flow rate control in a flow rate adjustment range mode, in which the flow rate of heated hot water gradually decreases while the flow rate of bypass hot water is maintained at a predetermined minimum flow rate, in the process where the rotation angle of the motor drive shaft for a valve operation changes from a predetermined first angle to a second angle. With such a configuration, the total number of valve devices (flow control valves) used in the hot water apparatus can be reduced, making it possible to achieve simplification of the overall configuration of the hot water apparatus and reduction of manufacturing cost.

On the other hand, in the case of using the aforementioned valve device, it is conceivable to increase the rotation angle of the motor drive shaft of the valve device, and set the valve device to a state where the flow rate of heated hot water is zero and the flow rate of bypass hot water is zero in the flow rate adjustment range mode, as a means to prevent output of high-temperature hot water, when the hot water apparatus has abnormality in outputting high-temperature hot water or when there is such a risk.

However, if such a means is adopted, the flow rate of heated hot water increases at the stage where the valve device transitions, for example, from the temperature adjustment range mode to the flow rate adjustment range mode. In this case, high-temperature hot water output is not immediately prevented, and during the period before hot water output is prevented, there is a risk that the flow rate ratio of heated hot water to bypass hot water may increase temporarily, and the hot water outlet temperature may actually become higher. It is required to appropriately prevent such a risk.

The disclosure, conceived under the aforementioned circumstances, aims to provide a hot water apparatus that is capable of appropriately preventing or suppressing output of abnormally high-temperature hot water while using a valve device capable of flow rate control in a predetermined temperature adjustment range mode and a flow rate adjustment range mode, as a hot water flow rate control means.

The disclosure employs the following technical means.

A hot water apparatus provided by the disclosure includes: a water inlet passage and a hot water outlet passage respectively connected to an inlet side and an outlet side of a heat exchanger for hot water heating; a bypass passage bypassing the heat exchanger to connect the water inlet passage and the hot water outlet passage to each other, and mixing hot water from the water inlet passage, as bypass hot water, with heated hot water flowing through the hot water outlet passage; a valve device capable of changing a flow rate of the heated hot water flowing through the hot water outlet passage and a flow rate of the bypass hot water flowing through the bypass passage; and an abnormality detection part capable of detecting occurrence or risk of output of abnormally high-temperature hot water in which hot water at a predetermined high temperature or above is output from the hot water outlet passage to exterior. The valve device is configured to be capable of sequentially executing flow rate control in a temperature adjustment range mode and flow rate control in a flow rate adjustment range mode in a process where a rotation angle of a motor drive shaft for a valve operation changes between a predetermined first angle and a second angle. The flow rate control in the temperature adjustment range mode gradually increases the flow rate of the heated hot water while gradually decreasing the flow rate of the bypass hot water, and the flow rate control in the flow rate adjustment range mode changes a total flow rate of hot water flowing through the valve device so that the flow rate of the heated hot water gradually decreases while the flow rate of the bypass hot water is maintained at or below a predetermined minimum flow rate. When occurrence or risk of output of abnormally high-temperature hot water is detected by the abnormality detection part, in a case where the valve device is in the temperature adjustment range mode, control is executed to set the rotation angle of the motor drive shaft to the first angle, and in a case where the valve device is in the flow rate adjustment range mode, control is executed to set the rotation angle of the motor drive shaft to the second angle.

This configuration provides the following effects. That is, when output of abnormally high-temperature hot water has occurred or is likely to occur, in a case where the valve device is in the temperature adjustment range mode, control is executed to set the rotation angle of the motor drive shaft to the first angle. In this case, the flow rate of the bypass hot water increases while the flow rate of the heated hot water decreases. On the other hand, when output of abnormally high-temperature hot water has occurred or is likely to occur, in a case where the valve device is in the flow rate adjustment range mode, control is executed to set the rotation angle of the motor drive shaft to the second angle. In this case, the flow rate of the heated hot water gradually decreases while the flow rate of the bypass hot water is maintained at or below the predetermined minimum flow rate. Therefore, in either case, the flow rate ratio of heated hot water to bypass hot water does not temporarily increase, and the flow rate of heated hot water can be sequentially reduced to zero or brought close to zero. Consequently, it is possible to appropriately prevent or suppress output of abnormally high-temperature hot water without causing a malfunction that the hot water outlet temperature rises temporarily.

In the disclosure, when occurrence or risk of output of abnormally high-temperature hot water is detected by the abnormality detection part, in a case where the valve device is at a boundary between the temperature adjustment range mode and the flow rate adjustment range mode, control may be executed to set the rotation angle of the motor drive shaft to an angle among the first angle and the second angle on a side where an angle difference from the boundary is small.

With this configuration, when output of abnormally high-temperature hot water has occurred or is likely to occur, in a case where the valve device is at the boundary between the temperature adjustment range mode and the flow rate adjustment range mode, it is possible to minimize the time until the flow rate of heated hot water is reduced to zero in the valve device thereafter.

Other features and advantages of the disclosure will become more apparent from the description of the embodiments of the disclosure given below with reference to the attached figures.

The following describes specifically exemplary embodiments of the disclosure with reference to the figures.

A hot water apparatus WH shown inis configured as a hot water supply apparatus, and includes a premixing device, a combustion device C (premixing combustion device), a heat exchanger, hot water passagestoto be described later, a valve device A, a controller, and an outer casethat houses these components internally and has a water inletand a hot water outlet.

The combustion device C is configured by combining a fanand a burner partwith the premixing device. The premixing deviceis a device that generates a gaseous mixture (combustible gaseous mixture) of air and fuel gas. The gaseous mixture is supplied to the burner partby driving the fan. The burner parthas a configuration in which a porous platewith multiple ventilation holesis housed in a case, and an ignition plugis attached. The gaseous mixture passes through the multiple ventilation holes, and combusts below the porous plate. Combustion gas generated by the burner partacts on the heat exchanger, and the hot water passing through this heat exchangeris heated. The heat exchangerincludes, for example, a primary heat exchange partA and a secondary heat exchange partB for sensible heat recovery and latent heat recovery, but is not limited thereto, and can also be configured with only the heat exchange partA for sensible heat recovery. After passing through the heat exchanger, the combustion gas passes through an exhaust duct partof the caseand is discharged to the exterior as exhaust gas.

The water inletis, for example, a part where a water pipe is connected, and unheated hot water is supplied from the exterior. The hot water outletis a part for outputting hot water heated by the heat exchangerto an external hot water outlet destination.

The hot water apparatus WH has hot water passages including a water inlet passage, a hot water outlet passage, and a bypass passage.

Here, the water inlet passageis a hot water passage from the water inletto an inletof the heat exchanger. The water inlet passageis provided with the valve device A, a flow rate sensor Sa, and a temperature sensor Sb for detecting the water inlet temperature. The water inlet passageis divided into two passagesandwhich are located on the upstream side and downstream side of the valve device A, respectively.

The hot water outlet passageis a hot water passage from an outletof the heat exchangerto the hot water outlet. The hot water outlet passageis provided with a temperature sensor Sc for detecting an outlet side temperature of the heat exchanger, a temperature sensor Sd for detecting abnormally high temperatures, and a temperature sensor Se for detecting the hot water temperature (hot water outlet temperature) on the downstream side of the connection point of the bypass passage.

The combination of the temperature sensors Sc and Sd and the controller, as will be described later, constitutes the “abnormality detection part” referred to in the disclosure.

The bypass passageis a hot water passage that connects a part of the valve device A, which corresponds to an intermediate point of the water inlet passage, to an intermediate point Pa of the hot water outlet passageto bypass the heat exchanger. Part of the hot water flowing through the water inlet passagecan be passed through the bypass passageto flow into the intermediate point Pa of the hot water outlet passage. This makes it possible to generate mixed hot water with adjusted temperature by mixing the heated hot water in the hot water outlet passagewith the bypass hot water flowing through the bypass passage, and to output this mixed hot water from the hot water outlet.

The valve device A is a device capable of changing a flow rate Qa of the heated hot water flowing through the hot water outlet passageand a flow rate Qb of the bypass hot water flowing through the bypass passage.

Into, the valve device A includes a casehaving a first port Pto a third port P, a valve body(A,B) as a rotary valve body disposed in this case, and a drive shaft(motor drive shaft) of a motor M for rotating this valve body.

The motor M is, for example, a stepping motor, and rotation angle control of the drive shaftconnected to the valve bodyis possible.

In this embodiment, the valve device A is set to be used as a distribution valve that enables hot water flowing into the third port Pto flow out to the first port Pand the second port P(refer also to). The passageon the upstream side of the water inlet passageis connected to the third port P, and unheated hot water supplied to the water inletflows in. The passageon the downstream side of the water inlet passageis connected to the second port P, and the hot water flowing out from this second port Pis sent to the heat exchanger. The bypass passageis connected to the first port P, and the hot water flowing out from this first port Pflows through the bypass passage, and flows into the intermediate point Pa of the hot water outlet passage.

Into, partition wall partstoforming openingstofor passing water are provided at positions close to the valve bodyinside each of the first port Pto the third port Pof the case.

Further, the valve bodyis a combination of a substantially cylindrical first valve bodyA that is open on the third port Pside, and a second valve bodyB that is connected to the lower part of the first valve bodyA and rotates with the rotation of the first valve bodyA.

In the peripheral wall part of the first valve bodyA, a first openingand a second openingfor passing water are provided to extend in the circumferential direction. The second valve bodyB is provided with a third openingfor communication with the third port P, and a blocking partthat is fan-shaped when viewed from the bottom (refer also toand). The hot water flowing into the third port Pcan flow into the inside of the valve bodythrough the third opening, and then flow to the first port Pand the second port Pfrom the first openingand the second openingthrough the openingsand.

As shown in, the valve device A is capable of sequentially executing flow rate control in a temperature adjustment range mode and flow rate control in a flow rate adjustment range mode by changing the rotation angle of the motor drive shaftand the valve body.

More specifically, the rotation angle of the motor drive shaftand the valve bodycan be changed from a predetermined first angle al to a second angle αbeyond a predetermined boundary angle α. The angular arrangement of the valve bodyshown intocorresponds to the first angle α.toandtocorrespond to the boundary angle αand the second angle α, respectively.

When setting the first angle aas shown into, the flow rate Qb of the bypass hot water is at the maximum, and the flow rate Qa of the heated hot water flowing through the hot water outlet passageis zero.

That is, in this state, the third openingis not blocked by the valve body(second valve bodyB), allowing hot water to flow into the valve body. On the other hand, the communication area between the first openingand the first port Pis large, allowing a large amount of hot water to flow from the first port Pto the bypass passage. The second openingand the second port Pare not in communication, so no hot water flows from the second port Pto the heat exchanger.

From the first angle al to the boundary angle αis the temperature adjustment range mode. In this temperature adjustment range mode, as the rotation angle of the drive shaftand the valve bodyincreases, the flow rate Qb of the bypass hot water gradually decreases, while the flow rate Qa of the heated hot water flowing through the hot water outlet passagegradually increases.

That is, while the valve bodyrotates in the direction indicated by arrow Da from the state shown intoto the angle shown into, the communication opening area between the first openingand the first port Pgradually decreases. Therefore, the flow rate Qb of the bypass hot water gradually decreases. The first opening, as shown in, extends in the circumferential direction at an appropriate angle θ1, but the vertical width Wthereof (and) becomes narrower as it moves away from one endIn contrast, the communication area between the second openingand the second port Pgradually increases. The second opening, as shown in, extends in the circumferential direction at an appropriate angle θ2, but the vertical width Wthereof becomes wider as it moves away from one end

In the configuration shown in, when the rotation angle of the valve body(and the motor drive shaft) is at the boundary angle α, the flow rate Qb of the bypass hot water becomes zero. Alternatively, it may be configured so that the flow rate becomes a small amount close to zero (the virtual line portion in).

From the boundary angle αto the second angle αis the flow rate adjustment range mode. In this flow rate adjustment range mode, as the rotation angle of the motor drive shaftand the valve bodyincreases, while maintaining the flow rate Qb of the bypass hot water at or below a predetermined minimum flow rate (zero or a small amount close to zero), the total flow rate of hot water flowing through the valve device A is changed so that the flow rate Qa of the heated hot water flowing through the hot water outlet passagegradually decreases. Eventually, the flow rates Qb and Qa of the bypass hot water and heated hot water both become zero.

That is, when the valve bodyreaches the angle shown into, the openingfor passing water is completely closed by the blocking partof the second valve bodyB, and hot water no longer flows into the third port P. As a result, the flow rates Qa and Qb become zero. In the process of the valve bodychanging fromtototo, although the second openingand the second port Pare in communication, the opening area of the openingfor passing water gradually decreases, and the flow rate of hot water into the third port Pand the inside of the valve bodydecreases, causing the flow rate Qa to decrease.

In the flow rate adjustment range mode, the total flow rate of hot water flowing through the valve device A may be changed while maintaining the ratio of the flow rate of the bypass hot water to the flow rate of the heated hot water at the boundary angle α.

The controlleris configured using a microcomputer or the like, and executes operation control and data processing of each part of the hot water apparatus WH, as well as controls the operation of the valve device A. This controlleris capable of detecting a situation when the temperature detected by the temperature sensors Sc and Sd is abnormally higher than a predetermined reference temperature, and output of abnormally high-temperature hot water has occurred or is likely to occur, in which hot water at a predetermined high temperature or above is output from the hot water outletto the exterior. When this is detected, the controllercauses the valve device A to perform a predetermined operation to prevent or suppress abnormally high-temperature hot water from being output from the hot water outlet. Nevertheless, the details will be described later.

It should be noted that a remote control (not shown) installed in the kitchen or bathroom is communicatively connected to the controller, and by using this remote control, the target hot water supply temperature, etc. can be set appropriately.

Next, an example of the operation processing procedure of the aforementioned hot water apparatus WH will be described with reference to the flowchart in, together with the function of the hot water apparatus WH.

First, during normal times when the hot water apparatus WH is not executing a hot water supply operation, the motor drive shaftand the valve bodyof the valve device A are controlled to be at the boundary angle α(S). Next, when a hot water supply terminal (not shown) connected by piping to the hot water outletof the hot water apparatus WH is opened, hot water starts to flow to the water inlet passage, and the flow rate of hot water flowing through the heat exchangerbecomes equal to or greater than a predetermined minimum operating flow rate (MOQ-ON), which is detected based on the detection signal from the flow rate sensor Sa, the burner partis turned on (S: YES, S). As a result, hot water heating using the heat exchangerbegins, and hot water output from the hot water outletis initiated. During such a hot water supply operation, the controllerexecutes a normal operation to control the flow rate Qa of heated hot water and the flow rate Qb of bypass hot water in the valve device A so that the hot water outlet temperature from the hot water outletbecomes the desired target hot water supply temperature (S).

During the aforementioned hot water supply operation, if it is determined in the controllerthat output of abnormally high-temperature hot water has occurred or is likely to occur, the burner partis driven off (S: YES, S), and the following operation control is executed.

That is, in a case where the valve device A is in the aforementioned temperature adjustment range mode at this time point, control is executed to set the rotation angle of the motor drive shaftand the valve bodyto the first angle α(S, S: YES, S). In the process of executing this control, as understood from, the flow rate Qb of bypass hot water gradually increases, while the flow rate Qa of heated hot water decreases. When the first angle al is reached, the flow rate Qb of bypass hot water becomes maximum, and the flow rate Qa of heated hot water becomes zero. Therefore, the hot water outlet temperature from the hot water outletcan be lowered without a rise even temporarily, making it possible to prevent or suppress output of abnormally high-temperature hot water.

Unlike the aforementioned operation control, if control is performed to set the rotation angle to the second angle αdespite that the valve device A is in the temperature adjustment range mode when it is determined that output of abnormally high-temperature hot water has occurred or is likely to occur, the flow rate Qa of heated hot water increases during the period until the boundary angle αis reached, causing the hot water outlet temperature to rise. According to this embodiment, such a problem can be appropriately avoided.

Different from the aforementioned, in a case where the valve device A is in the aforementioned flow rate adjustment range mode when it is determined that output of abnormally high-temperature hot water has occurred or is likely to occur, control is executed to set the rotation angle of the motor drive shaftand the valve bodyto the second angle α(S: NO, S: YES, S). In the process of executing this control, while the flow rate Qb of bypass hot water is maintained at a predetermined minimum flow rate, the flow rate Qa of heated hot water decreases. Eventually, both the flow rate Qb of bypass hot water and the flow rate Qa of heated hot water become zero. Therefore, in this case, the hot water outlet temperature from the hot water outletcan also be lowered without a rise even temporarily, making it possible to prevent or suppress output of abnormally high-temperature hot water.