JPS6332243A - Flow rate sensing device for heat exchanger - Google Patents

Abstract

PURPOSE:To improve an accuracy of sensing operation when an operation is started and to enable rapid heating to be performed up to a normal heating condition by a method wherein sensed outputs from a first and a second temperature sensing means are inputted to a comparator and an amount of water is calculated in reference to an output from the comparator, a heating calorie of a gas burner and a thermal efficiency of an endothermic unit part. CONSTITUTION:Endothermic unit parts 10 and 10 of a heat exchanger 1 are heated. Since a heating calorie under a combustion in a gas burner B is high and fins 12 and 12 are present in the endothermic unit parts 10 and 10, a temperature of the endothermic unit part 10 is increased. The corresponding endothermic unit part 10 of the first and second temperature sensing means 22 and 23 is positioned at the upper- most upstream side and after a heat exchanger 1 is started to operate, a variation in temperature is sensed at first. A sensed output from the sensed first and second temperature sensing means 22 and 23 is inputted to a comparator 3, an amount of passed water in a water circuit 2 is calculated by a calculation device 4 in reference to an amount of combustion and a thermal efficiency of the gas burner B and then inputted to an output device. With this arrangement, a time required to attain a normal heated condition is shortened and an accuracy of sensing when the operation is started to operate is increased.

Description

Detailed Description of the Invention (Field of Application and Summary of the Invention) The present invention relates to a flow rate detection device for a heat exchanger, particularly a device that heats a water circuit and detects the flow rate based on the temperature change at that time. It can be used as a flow rate detection device for forward control.

Further, the present invention aims to improve the responsiveness of this detection device at the time of startup by detecting the degree of temperature rise of the heated fluid passing through the heated tube heated by the heat source of the heat exchanger. It is.

(Prior art and its problems) The flow rate of the water circuit of the heat exchanger is detected, and the combustion amount of the burner as a heating source is controlled to a predetermined value based on the relationship between the detected flow rate and the set hot water temperature. , has already applied for a special application in 1982.
There is one disclosed in Japanese Patent No.-173335.

This is a heat exchanger (water circuit (2), as shown in Figure 7).
), a first heat-sensitive element (21a) and a second heat-sensitive element (21b) of indirect heating type or self-heating type are arranged at regular intervals, and the first heat-sensitive element (21a) is located upstream of the second heat-sensitive element (21b), and these two first... Second heat sensitive element (21a).

The output from the r21b) is input to the comparator (3), and the amplified output from the comparator (3) is used to control the gas burner (B).
A gas proportional valve (31) inserted into the circuit to is driven.

In this conventional example, as the amount of water flowing through the water circuit (2) increases, the degree of heating by the heater (H) of the second heat-sensitive element (21b) decreases. On the other hand, when the flow rate of water decreases, the detected temperature increases, and the comparator (3) performs a comparison calculation between the detected temperature of the first heat-sensitive element (21a) and the detected temperature of the second heat-sensitive element (21b). Changes in water volume can then be detected. Therefore, by converting the output of this comparator (3) into a predetermined hydraulic power and inputting it to the gas proportional valve (31), the combustion amount of the gas burner (B) can be adjusted according to the change in the amount of water flowing through the water circuit (2). This means that the hot water temperature can be maintained at the set temperature even if the water flow rate changes. Therefore, this one is the first one. The combination of the second heat sensitive element (2+a), (21b) and the comparator (3) and the amplifier functions as a drive device for the gas proportional valve (3), and the first and second heat sensitive elements (21a), (21b) and comparator (3) function as a flow rate detection device.

However, in this conventional device, the second heat sensitive element (21b
) is always in operation, and the flow rate detection unit cannot detect the flow rate with sufficient accuracy at the initial stage of ignition of the appliance.

When the appliance is started, the second heat-sensitive element (21b) simultaneously enters the detection state, but it takes a certain amount of time for the heater (H) to reach a steady state of heat generation, and during this start-up time,
This is because the difference in detected temperatures between the second heat-sensitive element (21b) and the first heat-sensitive element (21a) is not proportional to the amount of water flowing. This tendency becomes even more remarkable when the first heat-sensitive element (21a) and the second heat-sensitive element (2l b) are attached to the outside of the pipe wall of the water circuit (2), and in this case, the heater (H) is in a steady heating state. Even if it is, the difference in the detected temperatures between the first heat sensitive element (21a) and the second heat sensitive element (21b) will not be accurately proportional to the amount of water.

(Technical Problem) The present invention detects the amount of water by heating a part of the water circuit (2) that passes through the heat exchanger (1) and detecting the temperature change in this heated part, and the detection accuracy at the time of startup. In order to increase
The technical challenge is to enable the heating area for water volume detection to be rapidly heated to a steady state.

(Technical means) The technical means of the present invention taken to solve the above-mentioned technical problem is that the heat exchanger (1) is located at the most upstream side and the heat absorption pipe (
A first temperature detection means (22) is provided at the entrance to the endothermic unit (10) consisting of the heat absorbing unit (11) and the fins (12).
and a second temperature detection means (23) is provided at the outlet from the endothermic unit (10). Second
The detection outputs from the temperature detection means (22) and (23) are input to the comparator (3), and the output from the comparator (3), the combustion amount of the gas burner (B), and the endothermic middle part (1
0) is provided with an arithmetic device (4) that calculates the amount of water from the thermal efficiency.

(See Figure 1) (effect) The above technical means of the present invention operates as follows.

When the heat exchanger (1) is in operation, the gas burner (B)
enters a combustion state, and the endothermic unit (10
), (10) are heated. At this time, use the gas burner (
The amount of heat generated by combustion in B) is extremely large compared to that of conventional heaters (H), and moreover, the heat absorption unit (10)
, (10) is equipped with fins (12), (12), the amount of combustion heat of the gas burner (B) is transferred to the endothermic unit (10), and the heat absorption unit (10) is immediately transferred to the endothermic unit (10).
10) is heated. Moreover, the first and second temperature detection means (2
2) Since the corresponding endothermic units (10) of (23) are located on the most upstream side, temperature changes are detected first after the heat exchanger (1) starts operating.

In this way, the detected first . Second temperature detection means (
22) The detection outputs of (23) are input to the comparator (3), and the output from this comparator (3) and the gas burner (B)
The amount of water flowing through the water circuit (2) is calculated by the calculation device (4) from the combustion amount and thermal efficiency of the water, and is inputted to the output device.

(Effects) Since the present invention is a -1-synthetic acid, it has the following unique effects.

The first point is provided to detect the amount of water flowing. The endothermic unit (10) between the second temperature detection means (22) and (23) is heated with high calories by the combustion exhaust of the gas burner (B), and the rapid heating efficiency of the endothermic unit (10) is high. Since the efficiency is higher than that of only the heat absorbing tube (11), the time required for this part to reach a steady heating state is shortened, and the detection accuracy at the time of start-up is increased. In other words, the rise-L rise time until the detection state is reached is extremely short. In addition, the endothermic unit (10
) is the object of detection, so the above effect is excellent in this respect as well.

Next, the first. Second temperature detection means (22), (23)
This is because it is simply attached to the pipe wall of the water circuit (2).

These mounting structures become simpler.

(Example) Hereinafter, an example of the present invention will be described based on the drawings of FIGS. 2 to 4.

The first embodiment shown in FIGS. 2 and 3.

As shown in FIG. 3, the first unit has a plurality of endothermic units (10), (10) arranged and communicated in a plane. second heat absorption part (la),
(lb) are arranged in parallel in two stages, upper and lower. The second heat absorption parts (la) and (lb) are communicated with each other, and the gas burner (
B) The first heat absorption part (l
The first. Second temperature detection means (22), (2
3), and the first heat absorbing part (la) is located upstream of the second heat absorbing part (lb) in the water circuit (2).

In addition, the gas circuit to the gas burner (B) is equipped with a gas proportional valve (
31) is inserted, and this gas proportional valve (31) is controlled by an output control device (5).

This output control device (5) is equipped with a slow ignition device, and at the initial stage of ignition of the gas burner (B), the gas burner (B) always passes through a constant combustion amount state and then shifts to a set combustion state. For this reason, this output control device (5) includes an ignition initial gas amount setting means (51), and at the initial stage of ignition, the gas proportional valve (31) is set for a certain period of time by the ignition initial gas amount setting means (51). The opening is set to a certain degree. After that, the output control device (
5), the opening degree is set according to the output from the arithmetic device (4), and the outlet temperature is maintained at the set temperature.

For this reason, 1. Second temperature detection means (22), (23
) is input to the comparator (3), and this comparator (
As mentioned above, the output of 3) is input to the calculation device (4), and from the combustion amount set by the 1 ignition initial gas amount setting means (51) and the thermal efficiency of the endothermic unit (10), The amount of water passing through the water circuit (2) is calculated, and an output corresponding to this output is sent from the output control device (5) to the gas proportional valve (31).
) and operates as described in -F.

Next, in the second embodiment shown in FIG.
There is one in which the detection output is input to an arithmetic unit (0).

In this one, the first. Second temperature detection means (22), (
23) is inputted, the thermal efficiency of the endothermic unit (10), and the detected temperature of the third temperature detection means (24), the flow rate is calculated by the calculation device (0).

In this case, since the temperature detected by the third temperature detection means (24) is proportional to the amount of combustion, the amount of water passing through the water circuit (2) can be detected even under conditions where the amount of combustion of the gas burner (B) changes. becomes. Therefore, even if the amount of water changes while using hot water from the water heater, the first The temperature difference between the second temperature detection means (22) and (23) and the output of the third temperature detection means (24) which is proportional to the gas amount, and more! The amount of water can be calculated from the relationship between ± and thermal efficiency, and the hot water temperature can be maintained at the set temperature.

As the signal corresponding to the gas flow rate, an input signal to a proportional valve can also be adopted.

Next, the third embodiment shown in FIG. 5 is similar to the first embodiment described above. This is a combination of the feedforward control and feedback control of the second embodiment, and a fourth detection means (25) is provided on the outlet side of the heat exchanger (1), and this output is used to maintain the hot water temperature at the set temperature. That is. For this reason,
The output from the temperature setting means (6) and the fourth detection means (2)
5) is input to the comparator (70), and this comparator (
70), the output from the comparator (70) is input to the drive circuit (B2) via the changeover switch (B1), and the output from the drive circuit (82) is input to the gas proportional valve (31). is input.

Also, 1st. The output of the flow rate detection device consisting of the second temperature detection means (22), (23) and the yix device (4) is:

The output of the temperature setting means (6) and the other comparator (30
), and this comparator (30) provides a feedforward output, and the output of this comparator (30) is sent to the drive circuit (62) via a changeover switch (61). is input.

The changeover switch (61) is initially set to the comparator (3).
In order to input the output on the 0) side to the drive circuit (82), the circuit from the comparator (30) to the drive circuit (62) is made conductive, but when the output of the heat exchanger (1) reaches a certain condition. ,
The movable contact of the changeover switch (6!) is switched to the comparator (70) side by the changeover drive circuit (7).Therefore, the changeover drive circuit (7) switches the movable contact of the changeover switch (6!) to the comparator (70) side.
5) and the output from the temperature setting means (6), the detected temperature of the fourth detection means (25) reaches a temperature lower than the set temperature by - constant temperature (Δt). At this point, an output for switching is generated.

In addition, the timer (8) is equipped with a normally closed output contact,
When the gas burner (B) is ignited, the outputs from the comparator (30) and the comparator (70) are not manually applied to the drive circuit (82). The set time of this timer (8) coincides with the slow ignition time (T), and after the slow ignition time (T) has elapsed, its output contact is closed. Furthermore, due to the interlocking relationship between the changeover switch (81) and the gas proportional valve (31), the combustion amount during slow ignition is fixed in advance at a predetermined value, and the output from the comparator (30) and the comparator (70) The amount of gas to the gas burner (B) is set to a constant value under conditions that no input is made to the drive circuit (82).

In this embodiment, as shown in Fig. 6, the amount of combustion gas in the gas burner (B) is constant during the slow ignition time (T) at the start of operation of the appliance, and the amount of water is calculated under this condition, and the timer When the set time (8) has elapsed, the feedforward control proceeds based on the output from the comparator (30), and when the detected temperature of the fourth detection means (25) becomes a temperature lower than the set temperature by Δt, the switching drive is started. The temperature is controlled by switching to feedback control based on the output of the circuit (7).

In this case, the feedforward control is stopped at a temperature Δ lower than the set temperature, so it is possible to prevent the so-called overshoot phenomenon in which the hot water temperature exceeds the set temperature during this control, so the hot water temperature can be set quickly. The temperature can be approximated and stable feedback control can be performed. Note that the same effect can be obtained by using other flow rate detection devices in combination of this feedforward control and feedback control.

[Brief explanation of drawings]

FIG. 1 is a detailed diagram of the present invention, FIG. 2 is an explanatory diagram of the first embodiment, and FIG. 3 is a diagram of the first embodiment. Second heat absorption part (Ia),
(lb), FIG. 4 is an explanatory diagram of the second embodiment, FIGS. 5 and 6 are explanatory diagrams of the third embodiment, and FIG. 7 is an explanatory diagram of the conventional example. (1)...Heat exchanger (10)
... Endothermic unit (11) ... Endothermic tube (12)
...Fin (2)...Water circuit

Claims (1)

[Claims] In a device that heats a part of the water circuit (2) that passes through the heat exchanger (1) and detects the amount of water by capturing the temperature change in this heating section, it is located on the most upstream side of the heat exchanger (1) and Heat absorption tube (1
A first temperature sensing means (22) is provided at the inlet to the endothermic unit (10) consisting of the heat absorbing unit (10) and fins (12), and a second temperature detecting means (22) is provided at the outlet from the endothermic unit (10).
Temperature detection means (23) is provided, and the detection outputs from these first and second temperature detection means (22) and (23) are sent to a comparator (3).
), and is further equipped with an arithmetic device (4) that calculates the amount of water from the output from the comparator (3), the combustion amount of the gas burner (B), and the thermal efficiency of the endothermic unit (10). flow rate detection device