JPH07180906A - Hot water supplying apparatus - Google Patents

Abstract

PURPOSE:To provide a low-cost hot water supplying apparatus which can easily and effectively obtain hot water of a desired temperature, has high response of controlling the hot water temperature and a relatively simple structure in a bypass mixing type hot water supplying apparatus. CONSTITUTION:A bypass valve 28 in which a valve opening is regulated by a stepping motor is provided on the way of a bypass passage 14 disposed in parallel with a heat exchanger 6. The relationship between number of steps of the motor and a distribution ratio of hot water and water mixing is previously stored in memory means 40a of a controller 40. When a desired supply hot water temperature Ts is set, target number-of-steps calculating means 40b obtains target number of steps to become a feed-forward control amount by using data of the means 40a. Correction number-of-steps calculating means 40c calculates correction number of steps to become a feedback control amount in response to a supply hot water temperature Tm to be actually output, and valve drive means 40d controls the opening of the valve 38 according to both the numbers of the steps.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bypass mixing type water heater.

[0002]

2. Description of the Related Art Conventionally, in this type of water heater, a bypass valve is provided in the middle of a bypass passage arranged in parallel with the heat exchanger so that the hot water heated by the heat exchanger and the water passing through the bypass passage are separated from each other. Mix and adjust so that the hot water temperature reaches a predetermined level.

[0003] As such a bypass mixing type hot water heater, in the prior art disclosed in Japanese Patent Laid-Open No. 3-186150, based on a deviation between a hot water outlet temperature of a heat exchanger and a preset desired hot water temperature. In addition to controlling the heating amount (combustion amount of the gas burner, etc.), the opening ratio of the bypass valve is controlled to change the distribution ratio for mixing the hot and cold water, thereby controlling the hot water supply temperature.

[0004]

However, in the conventional water heater having the above-mentioned structure, when the temperature is controlled so that hot water having a predetermined hot water temperature can be obtained, the amount of heating is adjusted and the valve of the bypass valve in the bypass path is adjusted. Since both of the adjustment of the opening degree are controlled, the both adjustments interfere with each other, and there is a problem in that the control so that the desired hot water supply temperature is achieved cannot be performed smoothly.

Further, there is also a problem that the control device becomes complicated in order to control both the adjustment of the heating amount and the adjustment of the valve opening.

The present invention has been made to solve the above-mentioned problems, and can easily and surely obtain hot water having a desired hot water supply temperature, has high responsiveness in hot water supply temperature control, and has a relatively structure. An object is to provide a simple and inexpensive water heater.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a hot water heated by a heat exchanger in which a bypass valve is provided in the middle of a bypass passage arranged in parallel with the heat exchanger. The following configuration is adopted in a bypass mixing type water heater that mixes water with the water that has passed through the bypass passage to adjust the temperature to a predetermined hot water supply temperature.

That is, in the first invention, the bypass valve is
While the valve element is configured to be opened and closed by a stepping motor, it is equipped with a controller that controls the hot water temperature, and this controller responds to the number of steps of the stepping motor that determines the valve opening of the bypass valve and the number of steps. Based on the storage means that stores data that determines the relationship with the distribution ratio of the hot and cold water mixture that is obtained in advance, the hot water temperature that is the target based on the incoming water temperature, the hot water outlet temperature from the heat exchanger, and the preset hot water supply temperature. Target step number calculating means for calculating a distribution rate of mixing and calculating a target step number S _FF based on the target distribution rate and the data in the storage means, an incoming water temperature, a hot water outlet temperature from a heat exchanger, and hot and cold water The distribution ratio of the actual hot and cold water mixture is calculated based on the actual hot water supply temperature after mixing, and the correction step number S is calculated based on the deviation between the actual distribution ratio and the target distribution ratio. A correction step number calculating means for calculating the _FB, the seek target step number S _FF number production steps has been corrected by the correction step number S _FB to _{S (= S FF + S FB} ), based on the production number of steps S Valve driving means for driving the stepping motor.

[0009] In water heater according to the second invention, in place of the water heater of the valve driving means of the first invention, based on the target number of steps S _FF and the number of steps of correction _{S FB, S = S FF ·} (1 + S FB / A) (where A is a constant), and the valve driving means for driving the stepping motor based on the actual step number S is obtained.

[0010]

In the water heater having the structure according to the first aspect of the present invention, when the hot water supply temperature is set and the calan or the like is opened, the target number-of-steps calculating means constituting the controller is configured to detect the incoming water temperature, the outgoing hot water temperature from the heat exchanger, and A target distribution ratio of hot and cold water mixture is calculated based on a preset hot water supply temperature, and a target step number S _FF is calculated based on the target distribution ratio and data stored in advance in the storage means.

Further, the correction step number calculation means calculates the distribution ratio of the actual hot and cold water mixture based on the incoming water temperature, the hot water discharge temperature from the heat exchanger, and the actual hot water supply temperature after hot and cold water mixing, and this actual distribution The correction step number S _FB is calculated based on the deviation between the rate and the target distribution rate obtained in the calculation process of the target step number calculation means.

The valve driving means uses the above-mentioned target step number S _FF.
The number of production step was corrected by the correction step number S _FB the S (=
S _FF + S _FB ) is obtained, and the stepping motor is driven based on this actual operation step number S.

As described above, the temperature is controlled so that a desired hot water supply temperature can be obtained by adjusting only the opening degree of the bypass valve provided in the bypass passage to change the distribution ratio for mixing the hot and cold water. Not only the structure of the control mechanism is simplified, but also the responsiveness of temperature control is improved, and hot water supply at a desired hot water supply temperature can be performed easily and accurately.

In the water heater according to the second aspect of the invention, S = S based on the target step number S _FF and the correction step number S _FB.
Since the actual step number S is calculated by S _FF · (1 + S _FB / A), even if the hot water supply temperature is changed, the influence of drift caused by changes over time in the hot water supply characteristics of the water heater can be reduced. Therefore, the hot water of the changed hot water supply temperature is stabilized within a short time.

[0015]

FIG. 1 is a schematic configuration diagram of a water heater according to an embodiment of the present invention.

The water heater 1 of this embodiment includes a heat exchanger 6 and
The gas burner 8 heats this.

The water inlet side of the heat exchanger 6 is connected to a water pipe (not shown) or the like, and the hot water outlet side of the heat exchanger 6 is connected to a run (not shown) or shower. The channels 12 are connected to each other, and the water inlet 10
The hot water outlet 12 and the hot water outlet 12 are short-circuited by a bypass passage 14 for bypassing the heat exchanger 6.

A water inlet temperature sensor 16 for detecting the water inlet temperature Tc is provided in the water inlet passage 10 while the hot water outlet passage 1 is provided.
Reference numeral 2 denotes a hot water outlet temperature sensor 22 for detecting a hot water outlet temperature Th of the hot water heated by the heat exchanger 6, and hot water supply after the hot water heated by the heat exchanger 6 and the water passing through the bypass passage 14 are mixed. A hot water supply temperature sensor 24 for detecting the temperature Tm is provided. Reference numeral 26 is an overflow servo valve that limits the amount of hot water discharged when the amount of water passing through the heat exchanger 6 exceeds the maximum heating capacity.

Further, the bypass passage 14 is provided with a bypass valve 28 for opening and closing the bypass passage 14.

As shown in FIG. 2, the bypass valve 28 is provided with a valve shaft 32 in an axially retractable manner in a case 30 having a water inlet 30a and a water outlet 30b.
The valve body 34 is attached to the tip end portion of the valve shaft 32, and the stepping motor 36 is fixed to the outer side portion of the case 30. The base end portion of the valve shaft 32 is attached to the output shaft of the stepping motor 36. The stepping motor 36 rotates to move the valve shaft 32 back and forth.
Thereby, the valve element 34 changes the opening degree of the water passage in the case 30.

Further, the water heater 1 has a controller 40 for controlling the temperature of the hot water, and an operating portion 42 for connecting to the controller 40 and giving a predetermined command is separately provided.

The controller 40 includes a storage means 40a, a target step number calculation means 40b, a correction step number calculation means 40c, and a valve drive means 40d.

The storage means 40a is composed of a ROM or the like, and as shown by the solid line in FIG. 3, it is obtained in advance according to the number of steps of the stepping motor 36 that determines the valve opening of the bypass valve 28 and each number of steps. Data is stored for determining the relationship with the distribution ratio of the mixed hot and cold water. That is, it is checked in advance how many steps the stepping motor 36 rotates to distribute the amount Qc of water passing through the bypass passage 14 and the amount Qh of hot water discharged from the heat exchanger 6. , The distribution ratio of the hot and cold water mixture ρ (= Qc / Q
Data obtained by plotting the relationship between h) and the number of steps is tabulated and stored in advance in the storage means 40a.

The target number-of-steps calculating means 40b is composed of an incoming water temperature Tc, a hot water outlet temperature Th from the heat exchanger 6, and an operating section 4.
The hot water supply temperature Ts preset in step 2 is used to calculate the distribution ratio ρ of the hot and cold water mixture that is the control target, and the target distribution ratio ρ
The target number of steps S _FF is calculated based on the data stored in the storage means 40a.

The correction step number calculation means 40c calculates the distribution ratio ρ'of the actual hot and cold water mixture based on the incoming water temperature Tc, the hot water temperature Th from the heat exchanger 6 and the actual hot water supply temperature Tm after the hot and cold water mixing. However, the deviation Δρ between the actual distribution ratio ρ ′ and the target distribution ratio ρ obtained by the target step number calculation means 40b.
The correction step number S _FB is calculated based on (= ρ′−ρ).

The valve driving means 40d has a target step number S _FF.
The number of production step was corrected by the correction step number S _FB the S (=
S _FF + S _FB ) is obtained, and the stepping motor 36 is driven based on this actual step number S.

Next, the hot water supply temperature control operation in the hot water supply device 1 having the above structure will be described.

Now, when the currant or the like is opened and water is supplied through the water inlet 10, this is detected by a water flow sensor (not shown) and combustion of the burner 8 is started.

In this case, the heating amount of the burner 8 is fed so that the temperature of the hot water heated by the heat exchanger 6 becomes a predetermined target hot water temperature Tho given based on the following equations (a) and (b). Forward control and feedback control are performed.

Here, when ρ = (Th-Ts) / (Ts-Tc), in FIG. 3, when ρmax ≧ ρ ≧ ρmin, Tho = Ts + β (where β is a constant) (a) In the case of ρ> ρmax and ρ <ρmin, Tho = ρ ₀ · (Ts−Tc) + Ts (where ρ ₀ is a constant) (b) On the other hand, the target step number calculation means 40 b constituting the controller 40 is Water input temperature Tc from the sensor 16,
Based on the hot water temperature Th from the hot water temperature sensor 22 and the hot water supply temperature Ts preset by the user in the operation unit 42, the amount Qc of water passing through the bypass passage 14 and the amount of hot water discharged from the heat exchanger 6 The target distribution rate ρ with Qh is calculated based on the following equation.

Ρ = Qc / Qh = (Th-Ts) / (Ts-Tc) (1) When this target distribution ratio ρ is obtained, the target step number calculation means 40b continues to be stored in advance in the storage means 40a. The target number of steps S _FF is obtained based on the stored data.
This is determined by setting the distribution ratio on the vertical axis as the target distribution ratio ρ in FIG. 3 and reading the number of one step on the horizontal axis corresponding thereto. Then, the value of the target step number S _FF is sent to the valve driving means 40d as a feedforward control amount for the bypass valve 28.

On the other hand, the correction step number calculating means 40c
Based on the above-mentioned incoming water temperature Tc, outgoing hot water temperature Th, and actual hot water supply temperature Tm after hot water mixing detected by the hot water supply temperature sensor 24, the distribution ratio ρ ′ of the actual hot water mixing is calculated based on the following equation.

Ρ '= (Qc / Qh)' = (Th-Tm) / (Tm-Tc) (2) When this actual distribution ratio ρ'is obtained, the correction step number calculation means 40c continues to set the target. Step number calculation means 4
Target distribution ratio ρ calculated based on equation (1) by 0b
And the deviation Δρ (= ρ′−ρ) of the actual distribution ratio ρ ′ are obtained, and the correction step number S _FB is calculated by the following equation.

[0034] _{S FB = K P · Δρ +} K I · Σ (Δρ) (3) Here, K _P: proportional coefficient K _I: integral coefficient and this correction step number S value of _FB bypass valve 28
Is also sent to the valve drive means 40d as a feedback control amount for the.

The valve driving means 40d obtains the actual step number S obtained by correcting the target step number S _FF with the correction step number S _FB by the following equation.

S = S _FF + S _FB (4) Then, the stepping motor 36 of the bypass valve 28 is rotated by the actual operation step number S.

As described above, since only the opening degree of the bypass valve 28 provided in the bypass passage 14 is adjusted to change the distribution ratio for mixing the hot and cold water, a quick and accurate hot water supply temperature control can be performed.

In the above-described embodiment, the storage means 40a stores in the storage means 40a data obtained in advance for the relationship between the distribution ratio ρ (= Qc / Qh) of hot and cold water mixing and the number of steps of the stepping motor 36 (corresponding to the solid line in FIG. 3). Is stored, but product dimensional error,
It is conceivable that the relationship between the distribution ratio ρ and the number of steps may actually change as shown by the alternate long and short dash line in FIG. 3 due to mounting error, aging, and the like. As a countermeasure against this, it is preferable that the target step number calculation means 40b perform the following processing.

Now, assume that the preset hot water supply temperature Tsa is equal to the actual hot water supply temperature Tma (Tsa = Tm
a), at this time, if the target distribution rate obtained by the equation (1) is ρa, the target step number calculation means 40 is obtained from the correspondence relationship of FIG.
The target step number obtained in b is S _FF a, and the correction step number obtained in the correction step number calculating means 40 c is −S _FB a, so the actual step number Sa determined by the equation (4)
The control is stable become _{Sa = S FF a-S FB} a.

By the way, considering a case where the hot water supply temperature set by the operation unit 42 is changed from Tsa to Tsb,
Accordingly, the target distribution rate is also changed from ρa to ρb.

At this time, even if the relationship between the distribution rate and the number of steps changes as shown by the one-dot chain line in FIG. 3 as described above, if the target distribution rate ρ is determined by the equation (1), the feedforward control is performed. The target number of steps S _FF b as a quantity is uniquely determined by the relationship of the solid line in FIG.

On the other hand, if the correction step number S _FB as the feedback control amount is not corrected,
Since the equation (3) includes an integral term, the number of correction steps immediately after the change is the value immediately before the change, that is, S _FB a is held as it is. The value of S _FB a has a large value as the relationship between the distribution rate and the number of steps changes from the solid line in FIG. 3 to the one-dot chain line. The number of production steps S to be performed is S
= S _FF b-S _FB a, which results in excessive correction.

Even in this case, the number of correction steps gradually stabilizes from S _FB a to S _FB b with the passage of time and becomes stable, but it takes an extra time for stabilization and the responsiveness of the temperature control becomes high. become worse.

Therefore, in order to obtain the hot water having the changed hot water supply temperature within a short time even if the hot water supply temperature is changed, the valve driving means 40d outputs the target step number calculation means 40b. Based on the target step number S _FF and the correction step number S _FB from the correction step number calculating means 40c, the actual step number S is calculated by the following equation (5).

S = S _FF · (1 + S _FB / A) (where A is a constant) (5) For example, when A = 145 is set, when ρc = 1 in FIG. 3, S _FB = -45, and when ρb = 0.8 according to the change in hot water supply temperature, S _FF
Since b = 70, the production step number S immediately after the change is
From the formula (5), S = 70. (1-45 / 145) = 48.
It becomes 3.

In this way, the actual operating step number S is determined in consideration of the characteristic change between the distribution rate and the step number, so that even if the hot water supply temperature is changed, the feedback control amount is used. The correction step number S _FB becomes a small value from the beginning, and the hot water of the changed hot water supply temperature is stabilized within a short time.

[0047]

According to the present invention, in the hot water supply system of the bypass bath mixing system, only the opening degree of the bypass valve provided in the bypass passage is adjusted to change the distribution ratio for mixing the hot and cold water to obtain a desired hot water supply temperature. Since the temperature control is performed so that the heating amount can be obtained, it is irrelevant to the means for controlling the heating amount, and not only the structure of the temperature control mechanism is simplified, but also the responsiveness of the temperature control is enhanced, and the hot water supply at the desired hot water supply temperature Can be done easily and accurately.

Particularly, since the bypass valve in which the valve element is driven by the stepping motor is adopted here, the relationship between the number of steps and the distribution ratio of hot and cold water is obtained in advance, and the target number of steps is determined based on this data. Since it can be obtained immediately, accurate and speedy temperature control can be achieved.

Further, particularly in the water heater according to the second aspect of the present invention, even when the hot water supply temperature is changed, the influence of the drift component due to the change in the hot water discharge characteristic of the water heater over time is reduced, so that it is short. Within a period of time, the hot water will be stabilized at the hot water temperature after the change.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a water heater according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a specific configuration of a bypass valve used in the water heater of FIG.

FIG. 3 is a characteristic diagram showing a relationship between the number of steps of a stepping motor stored in a storage unit that constitutes a controller and a distribution ratio of hot and cold water mixing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Water heater, 6 ... Heat exchanger, 10 ... Inlet, 12 ... Outlet, 14 ... Bypass, 22 ... Outlet temperature sensor, 24 ...
Hot water supply temperature sensor, 28 ... Bypass valve, 36 ... Stepping motor, 40 ... Controller, 40a ... Storage means, 4
0b ... Target step number calculation means, 40c ... Corrected step number calculation means, 40d ... Valve driving means, 42 ... Operation part.

Claims (2)

[Claims] 1. A bypass valve is provided in the middle of a bypass passage arranged in parallel with a heat exchanger to mix hot water heated by the heat exchanger and water passing through the bypass passage to a predetermined hot water supply temperature. In a bypass mixing type water heater to be adjusted, the bypass valve is configured such that a valve body is opened and closed by a stepping motor, and a controller for controlling the hot water temperature is provided, and the controller is a valve of the bypass valve. Storage means that stores data that determines the relationship between the number of steps of the stepping motor that determines the degree of opening and the distribution ratio of hot and cold water mixing calculated in advance according to the number of steps, the inlet water temperature, and the hot water outlet temperature from the heat exchanger. , And a target distribution ratio of hot and cold water mixture based on the preset hot water supply temperature, and based on the target distribution ratio and the data of the storage means, A target step number calculating means for calculating the number of steps S _FF, incoming water temperature, the hot water temperature from the heat exchanger, and based on the actual hot water temperature after the hot and cold water mixing, to calculate the actual distribution rate hot and cold water mixing, this A correction step number calculating means for calculating a correction step number S _FB based on a deviation between the actual distribution rate and the target distribution rate, and an actual operation step number S (that corrects the target step number S _FF by the correction step number S _FB = S _FF + S _FB ) and a valve drive means for driving the stepping motor based on the actual step number S, and a water heater. 2. The water heater according to claim 1, wherein instead of the valve driving means, S = S _FF · (1 + S _FB / A) based on the target step number S _FF and the correction step number S _FB. (Where A is a constant), and the hot water heater is provided with a valve drive means for driving the stepping motor based on the actual step number S.