JPH07180904A - Hot water-supplying apparatus - Google Patents

Abstract

PURPOSE:To allow an end output hot water temperature of an output hot water cock to smoothly follow up a set temperature by compensating influence of heat dissipation and absorption of a tube by controlling even if a length of the tube from a hot water supplying apparatus to the cock is considerable. CONSTITUTION:A temperature sensor 27 is mounted on the way of a hot water supply tube 17 from a hot water supplying apparatus 1 to an output hot water cock 19 to measure a temperature TP of the tube 17. A controller 15 calculates heat absorption and dissipation amounts between hot water at the time of passing the tube 17 and the tube 17 based on the temperature TP, a set temperature TS and a thermal capacity H of the tube 17, and controls combustion of a burner 9 based on the amounts. Further, the controller 15 calculates a hot water temperature drop due to heat dissipation from the tube 17 to the atmosphere, adds a correction temperature AT corresponding to the drop to the temperature TS, and so controls the combustion that an output hot water temperature TH of the apparatus coincides with (TS+DELTAT).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of hot water temperature control in a hot water supply device.

[0002]

2. Description of the Related Art In a general hot water supply device, as shown in FIG. 1, the hot water temperature TH at the hot water outlet of the device itself is detected, and as shown in FIG.
As shown in, feedback control is performed so that the hot water temperature TH at the outlet of the device (hereinafter referred to as the hot water output from the device) matches the set temperature TS (normally, feedforward based on the feed water temperature TC and the feed water amount Q). Control is also used). Various control measures have been implemented in order to quickly and accurately match the apparatus outlet hot water temperature TH with the set temperature TS.

[0003]

However, the temperature of the hot water actually supplied to the user is not the device hot water temperature TH as shown in FIG. It is called hot water temperature). Therefore, particularly when the pipe length from the hot water supply device to the hot water tap is considerable, the influence of heat radiation and heat absorption in the pipe cannot be ignored.

As a result, as shown in FIG. 3 (A), even if the follow-up performance of the apparatus discharge hot water temperature TH with respect to the set temperature TS is improved, the follow-up performance of the terminal discharge water temperature TE is not improved so much and the desired temperature There is a problem that it takes time to get hot water.

Further, especially when the outside air temperature is low, the heat radiation from the pipe to the outside air cannot be ignored, and as shown in FIG. 3 (B), an offset occurs between the terminal outlet hot water temperature TE and the set temperature TS. Sometimes. As a countermeasure, the user is currently setting the set temperature TS slightly higher than the desired temperature for use.

Therefore, an object of the present invention is to control the end hot water temperature at the hot water tap by compensating for the influence of heat radiation and heat absorption in the hot water supply device even if the hot water supply device to the hot water tap has a considerable length. It is to be able to follow the set temperature well.

[0007]

The first hot water supply apparatus according to the present invention is a heat balance calculation means for calculating the heat balance between the hot water supply pipe and the hot water when the hot water discharged from the device passes through the hot water supply pipe. When,
And a heating control means for controlling the heating amount when the hot water is generated based on the heat balance from the heat balance calculation means.

Further, the second hot water supply apparatus according to the present invention includes a correction temperature calculation means for calculating a correction temperature corresponding to a decrease in the hot water temperature generated when the hot water discharged from the apparatus passes through the hot water supply pipe, and this correction Target temperature changing means for changing the target temperature of the hot water based on the temperature.

[0009]

According to the first hot water supply device, the heating amount is controlled according to the heat balance between the hot water supply pipe and the hot water. Therefore, since the heating amount is adjusted to be larger or smaller in consideration of the amount of heat absorption and heat radiation in the hot water supply pipe in advance, the followability of the terminal hot water temperature to the set temperature during the control transition is improved.

According to the second hot water supply device, the target temperature is corrected by the amount of decrease in the hot water temperature in the hot water supply pipe. Therefore, the offset of the outlet hot water temperature at the time of steady control is reduced.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 4 shows a schematic structure of an embodiment of a hot water supply apparatus according to the present invention.

As shown in FIG. 4, in the hot water supply device 1, a water supply pipe 3, a heat exchanger 5, a hot water discharge pipe 7, a gas burner 9, a supply gas pipe 11, a proportional valve 13 for adjusting a gas amount, and a control device 15. Etc. are provided. The outlet of the hot water outlet pipe 7 is connected to a hot water tap 19 via an external hot water supply pipe 17. Furthermore, the remote controller 2 for setting the tap water temperature, etc.
0 is a water heater 1 through a wired or wireless communication channel
Connected to.

The water supply pipe 3 is provided with a water amount sensor 21 for measuring the water supply amount Q and a water temperature sensor 25 for measuring the water supply temperature TC. A hot water temperature sensor 27 for measuring the hot water temperature (apparatus hot water temperature) TH at the outlet of the hot water pipe 7 is attached. Furthermore, a pipe temperature sensor 27 for measuring the temperature TP of the pipe 17 is attached to the hot water supply pipe 17. The pipe temperature sensor 27 is preferably attached at a position where an average temperature of the pipe 17 is obtained, for example, an intermediate position between the hot water supply device 1 and the hot water tap 19.

The information Q, TC, TH, TP detected by these sensors 21, 23, 25, 27 and the set temperature TS issued by the remote controller 20 are input to the controller 15. The control device 15 controls the gas amount control valve 13 by performing a control calculation to be described later based on the input information when hot water is burned. As a result, the hot water temperature (end hot water temperature) TE at the hot water tap 19 is controlled so as to match well with the set temperature TS.

FIG. 5 shows a functional configuration of the control device 15.

As shown in FIG. 5, the control device 15 includes a feedforward calculation unit 51, a feedback calculation unit 53,
A heat capacity calculation unit 55, a correction calculation unit 57, a set temperature change detection unit 59, a hot water start detection unit 61, and a proportional valve adjustment unit 63 are provided.

The feedforward calculator 51 calculates a heat quantity value F1 per unit time required to heat the feed water to the set temperature TS based on the set temperature TS, the feed water temperature TC and the feed water amount Q. Feedback calculation unit 53
Calculates the calorific value F2 per unit time that should be corrected and added in order to make the deviation zero, based on the deviation between the actual apparatus outlet hot water temperature TH and the set temperature TS. In addition, this 2
Since well-known appropriate elements can be adopted as the arithmetic units 51 and 53, detailed description of the arithmetic processing will be omitted.
The calorific value F output from the known calculation units 51 and 53
The addition value (F1 + F2) of 1 and F2 is the device outlet temperature TH
Is a heat quantity value per unit time optimized for quickly and accurately matching the set temperature TS with the set temperature TS.

The heat capacity calculation unit 55 calculates the heat capacity H of the pipe 17.
(If the heat capacity of the hot water tap 19 cannot be ignored, this is also included). As a calculation method, for example, calculation is performed according to the following equation (1) based on the total length 1 of the pipe 17, the diameter d, the wall thickness t, the specific heat c and the density ρ, and the coefficient K.

[0020]

[Equation 1] In this case, in the right side of the equation (1), a fixedly fixed portion is stored in advance in a memory or the like, and only the value of the variable portion (for example, the pipe length 1) is determined ( For example, the pipe heat capacity H
Is calculated.

The correction calculator 57 calculates a heat radiation amount F3 per unit time from the hot water passing through the pipe 17 to the pipe 17, based on the set temperature TS, the pipe temperature TP and the pipe heat capacity H. The correction calculation unit 57 includes the hot water start detection unit 6
1 and the detection signal from the set temperature change detection unit 59,
Each time the tapping is started and the set temperature TS is changed, the calculation operation described below is performed.

The hot water discharge start detecting section 61 is a water quantity sensor 21.
Alternatively, it receives a signal from a water flow switch (not shown) to detect the start of hot water discharge, and the set temperature change detection unit 59 receives a signal from the remote controller 20 to detect a change in the set temperature TS.

When the start of hot water discharge or the change of the set temperature is detected, the correction calculation unit 57 firstly calculates the total amount of heat radiation ΔF in the pipe 17 (that is, the start of hot water discharge or the change of the set temperature) according to the following equation (2). The heat radiation amount from the time zero until the terminal hot water temperature TE is settled) is calculated. Note that the total heat dissipation ΔF
Is a positive value, this means heat dissipation to the pipe, and a negative value means it is heat absorption from the pipe.

[0024]

[Equation 2] Here, TS is the set temperature at the start of tapping or after the set temperature is changed, and TP is the pipe temperature immediately before the start of tapping or immediately before the set temperature is changed.

Next, the correction calculator 57 calculates the heat radiation amount F3 per unit time based on the total heat radiation amount ΔF. The heat radiation amount F3 is a time function whose absolute value decreases with the passage of time, and is a function having the following relationship with the total heat radiation amount ΔF.

[0026]

[Equation 3] Here, τ is the time constant τ of the terminal tapping temperature TE, and t is time.

This function can, of course, be theoretically defined, but in this embodiment, an experiment was conducted beforehand so that the heat radiation amount F3 at that time can be uniquely determined from the total heat radiation amount ΔF and the elapsed time. It is stored in advance in the memory in the form of a heat radiation amount data table or a heat radiation amount calculation formula defined based on the data measured in advance. The correction calculation unit 57 obtains the heat radiation amount F3 corresponding to the total heat radiation amount ΔF and the elapsed time by using the heat radiation amount data table in the memory or the heat radiation amount calculation formula.

The heat radiation amount F3 thus obtained is
The heat amounts F1 and F2 from the feedforward calculation unit 51 and the feedback calculation unit 53 are added, and the added value (F1 + F2 + F3) is input to the proportional valve operation unit 63. The proportional valve operating unit 63 displays the heat quantity addition value (F1 + F2).
The proportional valve 13 is operated so that the amount of heat per unit time corresponding to + F3) is supplied from the burner 9 to the water in the heat exchanger 5.

FIG. 6 shows how the control device 15 operates as described above.

FIG. 6A shows a feed-forward calculation section 51 and a feedback calculation section 5 during control transition.
The heat quantity value (F1 + F2) output from No. 3 is shown. This calorific value is the calorific value per unit time required to make the hot water discharge temperature TH of the device favorably follow the set temperature TS. FIG. 6 (B)
Indicates a heat radiation amount value F3 output from the correction calculation unit 57. This value corresponds to the amount of heat absorption and heat dissipation in the pipe 17 per unit time. Addition value of these calorific values (F1 + F2 + F3)
Is as shown in FIG. 6 (C).

The burner combustion is controlled so as to supply the amount of heat shown in FIG. 6 (C), and as a result, as shown in FIG. 6 (D), the apparatus outlet hot water temperature TH undergoes a transient change similar to an overshoot. However, the excess (or lack) heat amount of the overshoot-like portion compensates for heat radiation (or heat absorption) in the pipe 17, and as a result, the terminal tap water temperature TE
The followability to the set temperature TS of is improved.

FIG. 7 shows a modification of the heat capacity calculating section in the control device 15 of the above embodiment.

The heat capacity calculation unit 65 shown in FIG. 7 recursively calculates the pipe heat capacity H from the deviation between the hot water discharge temperature TH and the terminal hot water temperature TE at the time of starting hot water discharge or changing the set temperature in the past. Therefore, in this method, as shown in FIG.
As shown by a broken line in FIG. 3, a hot water temperature sensor 29 for measuring the terminal hot water temperature TE is further provided, and a detection signal thereof is input to the control device 15.

Now, FIG. 8 shows changes in the apparatus outlet hot water temperature TH (1) and the terminal hot water outlet temperature TE (1) at the start of hot water discharge performed at a certain time. The heat capacity calculation unit 65 monitors such a transient change with the apparatus outlet hot water temperature TH (1), and from the time zero until the terminal outlet hot water temperature TE (1) is settled (this settling time t
1 is preset in the timer 67) and the total heat radiation amount ΔF is calculated by the following equation. The total heat radiation amount ΔF corresponds to the area of the hatched portion shown in FIG.

[0035]

[Equation 4] Next, the heat capacity calculation unit 65 calculates the heat capacity H of the pipe by the following equation.
Calculate (1).

[0036]

[Equation 5] Here, TE (1) _0 is the end tapping temperature TE (1) at time 0, and TE (1) _t1 is the end tapping temperature TE (1) at settling time t1.

The heat capacity H (1) thus obtained is sent to the correction calculator 57, which then calculates the heat capacity H (1).
Use (1) at the next hot water start or opportunity to change the set temperature,
The correction heat quantity F3 is calculated by the method already described.

The heat capacity calculation section 65 obtains the heat capacity H (2), H (3), ... The heat capacity H is made accurate by repeating the cycle. After that, the correction calculation unit 57 performs calculation using this accurate heat capacity H.

FIG. 9 shows a functional configuration of the controller 15 in another embodiment of the present invention. This control is mainly performed by the terminal hot water temperature T due to steady heat radiation from the pipe 17 to the outside air.
The purpose is to eliminate the offset between E and the set temperature TS. By combining this control with the control of either of the previous two embodiments, it can be expected that both offset cancellation and control followability can be obtained.

The feature in FIG. 9 is the existence of the set temperature correction unit 69, and the feedforward calculation unit 51 and the feedback calculation unit 53 in the subsequent stage have the same known configuration as that shown in FIG. The set temperature correction unit 69
The correction temperature ΔT corresponding to the offset in the steady state is generated. This corrected temperature ΔT is added to the set temperature TS set by the user and input to the feedforward calculation unit 51 and the feedback calculation unit 53. That is, the set temperature correction unit 69 automatically corrects the set temperature TS in consideration of the offset, which is conventionally performed by the user.

FIG. 10, FIG. 11 and FIG. 12 show variations of the method of generating the correction temperature ΔT by the set temperature correction unit 69.

FIG. 10 shows that the terminal outlet temperature TE is actually detected in the steady state during tapping, and this and the apparatus outlet temperature TH are detected.
The difference (TH-TE) with the operational amplifier 691 is obtained, and this temperature difference (temperature drop in the pipe 17) is corrected temperature Δ.
The method is T.

FIG. 11 shows that the pipe temperature TP is detected in the steady state during tapping, and the difference (T
H-TE) with a predetermined increasing function (for example, FIG.
Is calculated by the calculation unit 693, and the function value is used as the correction temperature ΔT.

In FIG. 12, the outside temperature TK is measured, and a predetermined decreasing function (for example, a linear linear function as shown in FIG. 6B) with respect to this outside temperature TK is calculated by the calculating unit 695, and the function value is calculated. This is a method of setting the correction temperature ΔT.

By automatically generating such a correction temperature ΔT and correcting the set temperature TS, the offset of the outlet hot water temperature TE can be automatically eliminated.

Although some embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be carried out in various other modes without departing from the gist thereof. You can

[0047]

According to the first aspect of the present invention, since the amount of heat absorbed and radiated in the hot water supply pipe is estimated in advance, the heating amount is adjusted to be larger or smaller, so that the terminal hot water temperature at the time of control transition is adjusted. The followability to the set temperature of is improved.

According to the second aspect, the target temperature is corrected by the amount of decrease in the hot water temperature in the hot water supply pipe.
The offset of the outlet hot water temperature during the steady control is reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a conventional hot water supply device.

FIG. 2 is a block diagram showing control of a conventional water heater.

FIG. 3 is a diagram showing a problem of the conventional technique.

FIG. 4 is a schematic configuration diagram of an embodiment of a water heater according to the present invention.

FIG. 5 is a block diagram showing functions of the control device of the embodiment.

FIG. 6 is a diagram showing a state of control according to the embodiment.

FIG. 7 is a block diagram showing a modification of the heat capacity calculation of the embodiment.

FIG. 8 is a diagram showing a state of calculation according to the modification.

FIG. 9 is a block diagram showing functions of a control device according to another embodiment of the present invention.

FIG. 10 is a block diagram showing an example of a correction temperature calculation method in the embodiment.

FIG. 11 is a block diagram showing another example of a correction temperature and a calculation method.

FIG. 12 is a block diagram showing still another example of the correction temperature and the calculation method.

[Explanation of symbols]

 1 Hot Water Supply Device 9 Burner 13 Proportional Valve 15 Control Device 17 Hot Water Supply Pipe 19 Hot Water Tap 20 Remote Controller 21 Water Flow Sensor 23 Water Temperature Sensor 25 Hot Water Temperature Sensor 27 Pipe Temperature Sensor 29 Hot Water Temperature Sensor 51 Feedforward Calculation Unit 53 Feedback Calculation Unit 55, 65 Heat capacity calculation unit 57 Correction calculation unit 59 Set temperature change detection unit 61 Hot water start detection unit 63 Proportional valve operation unit 67 Timer 69 Set temperature correction unit

Claims (5)

[Claims] 1. A heating unit heats water to generate hot water,
In a hot water supply device for supplying hot water to a hot-water tap through a hot water supply pipe, heat balance calculation means for calculating a heat balance between the hot water supply pipe and the hot water when the hot water passes through the hot water supply pipe, and the heat balance. And a heating control unit that controls the heating unit based on the heat balance from the calculation unit. 2. The hot water supply apparatus according to claim 1, wherein the heating control means calculates a heating amount required to match the hot water temperature at the inlet of the hot water supply pipe with a set temperature, and the heating amount. A hot water supply apparatus comprising: a unit that corrects based on the heat balance; and a unit that controls the heating unit so as to supply the corrected heating amount to the water. 3. The hot water supply apparatus according to claim 1, wherein the heat balance calculation means determines the heat capacity of the hot water supply pipe based on a physical attribute value of the hot water supply pipe, and the heat balance based on the heat capacity. A hot water supply device characterized by calculating. 4. The hot water supply apparatus according to claim 1, wherein the heat balance calculation means calculates the heat balance based on the difference between the hot water temperature at the inlet of the hot water supply pipe and the hot water temperature at the tap. Hot water supply device characterized by: 5. The heating unit heats water to generate hot water,
In a hot water supply device that supplies this hot water to a hot water tap through a hot water supply pipe, a correction temperature calculation means for calculating a correction temperature commensurate with a temperature drop of the hot water that occurs when the hot water passes through the hot water supply pipe, and the correction temperature And a target temperature changing means for changing a target temperature of hot water to be generated by the heating unit based on the hot water supply device.