JP2001343158A - Hot water storage type electric water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot water storage type electric water heater capable of storing desired high temperature hot water from an upper portion of a hot water storage tank from the middle to completion of boiling. SOLUTION: Boiling-up hot water temperature detection means 8 is positioned at the upper portion of a heater 2, and there is provided a water injection pipe 10 having a water injection inlet 11 that opens facing an upper inner wall of a hot water storage tank 1. Hereby, cold water injected from the water injection inlet 11 strikes the upper inner wall of the hot water storage tank 1 and diffuses along the inner wall at an upper portion in the hot water storage tank 1. Therefore, temperature detection delay of the boiling-up hot water temperature detection means 8 is eliminated, and there is ensured driving interruption of a circulation pump 4 before the injected cold water flows down to a lower portion of the heater 2. Further, since the temperature of the hot water temperature pushed down to the lower portion of the heater 2 is prevented from lowering, desired high temperature hot water is stored from the upper portion of the hot water storage tank 1 from the course of boiling-up to completion of the boiling-up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water storage type electric water heater in which a heater is provided above a hot water tank and hot water is stored from above the hot water tank.

[0002]

2. Description of the Related Art Conventionally, this type of water heater is disclosed in Japanese Patent Application Laid-Open No. 7-23.
No. 9153 has the following. FIG. 9 is a configuration diagram of a conventional hot water storage type electric water heater described in the above publication, and FIG. 10 is a temperature distribution diagram in a hot water storage tank of the conventional hot water storage type electric water heater.

In FIG. 8, 1 is a hot water storage tank, 2 is a hot water storage tank 1
The heater 3 disposed at the upper part of the hot water storage tank 1 has a circulation path communicating the area above the heater 2 in the hot water storage tank 1 and the lower part of the hot water storage tank 1.
Is a circulation pump, 5 is a first temperature sensor located slightly above the heater 2 on the wall of the hot water tank 1, 6 is a second temperature sensor located below the hot water tank 1, and 7 is the heater 2 and the circulation pump 4.
Is an energization control device that performs the above control. Then, when the first temperature sensor 5 detects that the water in the upper region of the hot water storage tank 1 is rapidly heated by the heater 2 to become hot water and reaches, for example, 85 ° C., the circulation pump 4 is controlled by the power supply control device 7.
The first temperature sensor 5 detects that the cold water in the lower part of the hot water tank 1 is circulated to the high temperature hot water in the upper part of the hot water tank 1 and the temperature of the hot water in the upper region of the hot water tank 1 drops, for example, to 75 ° C. Then, the power supply control device 7 stops the circulation pump. By repeatedly driving and stopping the circulation pump 4 as described above, the entire hot water in the hot water storage tank 1 is heated. Upon detecting that the second temperature sensor 6 at the lower part of the hot water storage tank has reached the set temperature, the energization control device 7 energizes the heater 2 and activates the circulation pump 4.
Stop driving.

[0004]

However, in the above-mentioned conventional configuration, the first temperature sensor 5 for driving / stopping the circulation pump 4 is slightly above the heater 2 and the circulating water is in the upper region of the hot water storage tank 1. Because it is far from where it flows into
By the time the first temperature sensor 5 detects that the temperature of the hot water has dropped to 75 ° C., the circulated cold water flows down to the lower portion of the heater 2. Therefore, as shown in FIG. 2, the temperature distribution in the hot water storage tank is 75 ° C. or less at the lower portion of the heater 2, and the temperature difference between the upper portion and the lower portion becomes large, so that there is a problem that desired hot water cannot be stored.

The present invention has been made to solve the above-mentioned problems, and can store desired high-temperature hot water from the upper portion of a hot water tank from the middle of boiling to the completion of boiling. The purpose is to provide a vessel.

[0006]

In order to solve the above-mentioned problems, a hot water storage type electric water heater according to the present invention is provided with a heater above a hot water tank, a boiling water temperature detecting means above the heater, and a lower part of the hot water tank. And a circulation path connected to a water injection pipe having a water injection port that opens to face the inner wall of the hot water tank via a circulation pump.

Accordingly, the cold water injected from the water injection port collides with the inner wall of the upper part of the hot water tank and is diffused along the inner wall at the upper part of the hot water tank, so that the boiling water temperature detecting means located at the upper part of the heater is used. The delay of the temperature detection is eliminated, and the drive of the circulation pump can be stopped before the injected cold water flows down to the lower part of the heater. Therefore, since the temperature of the high-temperature water pushed down to the lower portion of the heater is not reduced, desired high-temperature water can be stored from the upper portion of the hot water storage tank until the boiling is completed from the middle of the boiling. In addition, heat loss from the circulation path can be reduced by positioning the water injection pipe, which is a part of the circulation path, inside the hot water tank.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is characterized in that a heater is provided at the upper part of the hot water tank and a boiling water temperature detecting means is provided at the upper part of the heater. By providing a circulation path connected to a water injection pipe having a water injection port that opens oppositely, the cold water injected from the water injection port collides with the inner wall of the upper part of the hot water tank and is diffused along the inner wall at the upper part of the hot water tank. Therefore, there is no delay in temperature detection by the boiling water temperature detection means positioned at the top of the heater, and the circulation pump can be stopped before the injected cold water flows down to the bottom of the heater. The desired high-temperature hot water can be stored from the upper part of the hot water storage tank all the way. Further, a diffusion effect can be obtained without using any special diffusion means. In addition, heat loss from the circulation path can be reduced by positioning the water injection pipe, which is a part of the circulation path, inside the hot water tank.

The invention described in claim 2 is particularly advantageous in claim 1.
By providing the boiling water temperature detection means described in the above in the vicinity of the injection port at the top of the hot water tank, the temperature detection of the injection cold water becomes sharp, there is no delay in temperature detection, and before the injection cold water flows down to the lower part of the heater The driving of the circulation pump can be stopped.

[0010] The invention described in claim 3 is particularly advantageous in claim 1.
The water injection pipe described in (1) is replaceable, so that when the predetermined characteristics cannot be obtained due to breakage or deformation of the water injection pipe, replacement becomes easy, and the predetermined characteristics can be recovered by a simple operation.

[0011] The invention described in claim 4 is particularly advantageous in claim 1.
The pump has a variable speed of low speed and high speed, and has a pump inlet temperature detecting means for detecting the temperature of the inlet of the circulating pump, wherein the difference between the temperature of the circulating pump inlet and the set boiling temperature is predetermined. The difference between the temperature at the circulating pump inlet and the set boiling temperature is large by providing a pump drive control unit that drives the circulating pump at a low speed when the temperature difference is equal to or more than the predetermined temperature difference, and at a high speed when the temperature difference is equal to or less than the predetermined temperature difference. At low speeds, reduce the amount of injection per unit time to prevent cold water from flowing down to the lower part of the heater.If the difference between the temperature at the inlet of the circulating pump and the set temperature for boiling is small, increase the speed to unit time. Increase the injection amount of
By bringing the temperature of the injected water as close as possible to the temperature of the boiling water when the boiling is completed, desired high-temperature water can be stored from the upper part to the lower part of the hot water storage tank.

According to a fifth aspect of the present invention, a heater is provided at an upper portion of a hot water tank, and a boiling water temperature detecting means is provided at an upper portion of the heater. A circulation path connected to a water supply pipe having a water supply port to be supplied is provided, and after the heater power supply is stopped, the temperature detected by the boiling water temperature detection means decreases to a predetermined temperature set in advance, or stops after a predetermined time has elapsed. A pump stop control unit is provided to continue pump drive after stopping the heater power supply, move the residual heat of the heater to the lower part of the hot water tank, prevent excessive temperature rise, and reduce the temperature difference between the upper part and the lower part of the hot water tank. Can store hot water.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the conventional example and the respective embodiments, the same reference numerals are given to components having the same configuration and the same operation, and a part of the description is omitted.

(Embodiment 1) FIGS. 1 and 2 are block diagrams of a hot water storage type electric water heater according to a first embodiment of the present invention, and FIG. 3 is a temperature distribution diagram in a hot water storage tank in the first embodiment.

In FIG. 1 and FIG. 2, reference numeral 8 denotes a boiling water temperature detecting means positioned above the heater 2, which is installed on the outer can wall of the hot water storage tank 1. 9 is a pump inlet temperature detecting means for detecting the temperature of the inlet of the circulation pump 4, and 10 is a water injection pipe having a water injection port 11 opened inside the hot water storage tank 1 so as to face the inner wall of the hot water storage tank upper part. The can wall penetration is configured to be removable by a flange 12, and the flange 12 is connected to the circulation path 3 on the outlet side of the circulation pump 4 via a pipe joint 13. Reference numeral 14 denotes a control device that drives and controls the heater 2 and the circulation pump 4. Also, as shown in FIG.
The water inlet 11 is located near the boiling water temperature detecting means 8.

The operation and operation of the hot water storage type electric water heater configured as described above will be described below.

First, at the start of boiling, the water in the upper region of the hot water storage tank 1 is rapidly heated by the heater 2 to become hot water. When the hot water temperature detecting means 8 detects, for example, that the temperature has reached 90 ° C., The circulation pump 4 is driven by the control of the control device 12, and the lower cold water in the hot water tank 1 is circulated to the high-temperature hot water in the upper part of the hot water tank 1 to lower the hot water temperature in the upper region of the hot water tank 1, for example, 88.
° C is detected by the boiling water temperature detecting means 8,
The control device 12 stops the circulation pump 4. By repeatedly driving and stopping the circulation pump 4 as described above, the entire hot water in the hot water storage tank 1 is heated. The controller 12 stops the energization of the heater 2 and the drive of the circulation pump 4 when the boiling water temperature detecting means 8 detects that the temperature reaches the set boiling temperature (for example, 91 ° C.).

As described above, in the present embodiment, the boiling water temperature detecting means 8 is located above the heater 2 and the hot water tank 1
The provision of the water inlet 11 which is opened opposite to the upper inner wall allows the cold water injected from the water inlet 11 to collide with the upper inner wall of the hot water storage tank 1 and diffuse along the inner wall in the upper part of the hot water storage tank 1. The delay in temperature detection by the boiling water temperature detecting means 8 positioned above the heater 2 is eliminated, and the drive of the circulation pump 4 can be stopped before the injected cold water flows down to the lower portion of the heater 2. Without lowering the temperature of the depressed high-temperature water, and by locating the boiling water temperature detecting means 8 above the heater 2, the detection delay when the temperature rises when the circulation pump 4 is stopped is also reduced. As shown in FIG. 3, it is possible to store desired high-temperature hot water from the upper portion of the hot-water storage tank 1 from the middle of the heating to the completion of the heating, as shown in FIG. That.

The water injection pipe 1 which is a part of the circulation path 3
0 is located inside the hot water storage tank 1 so that the water injection pipe 1
0 is always in the high temperature range, and the length of the circulation path 3 exposed to the outside air is shortened, so that the heat radiation loss from the circulation path 3 can be reduced.

Since the boiling water temperature detecting means 8 is located near the opening of the water inlet 11 in the upper part of the hot water tank 1, the temperature detection by the boiling water temperature detecting means 8 is further improved, and the injection is performed. The cold water hardly flows down to the lower part of the heater 2.

The water injection pipe 10 inside the hot water storage tank has a replaceable structure having a flange 12 and a pipe joint 13 so that the water injection pipe can be replaced when predetermined characteristics cannot be obtained due to breakage or deformation of the water injection pipe. Becomes easier,
Predetermined characteristics can be restored with a simple operation.

(Embodiment 2) FIG. 4 is a block diagram of a hot water storage type electric water heater according to Embodiment 2 of the present invention, FIG. 5 is an explanatory diagram of a circulation flow rate and a temperature difference in Embodiment 2, and FIG. It is a temperature distribution figure in a hot-water storage tank. In FIG. 4, the circulation pump 4 has a variable speed of low speed and high speed, and 15 is a predetermined temperature difference between a temperature detected by the pump inlet temperature detecting means 9 and a temperature detected by the boiling water temperature detecting means 8. Temperature difference comparison unit to compare with
Reference numeral 16 denotes a pump drive control unit that drives the circulation pump 4 at low speed or high speed in response to the comparison result of the temperature difference comparison unit. The difference from the first embodiment is that a variable speed circulation pump 4 and a pump drive control unit 16 are provided. Is a point.

The operation and operation of the hot water storage type electric water heater configured as described above will be described below.

First, at the start of boiling, the water in the upper region of the hot water tank 1 is rapidly heated by the heater 2 to become hot water. When the hot water temperature detecting means 8 detects that the temperature has reached 90 ° C., for example, The circulation pump 4 is driven by the control of the control device 14. At this time, the difference between the temperature detected by the pump inlet temperature detecting means 9 and the temperature detected by the boiling hot water temperature detecting means 8 is compared with a predetermined temperature difference by a temperature difference comparing section, and the difference is set in advance. If the temperature difference is equal to or greater than the predetermined temperature difference (for example, 30 ° C.), the pump drive control unit 16 drives the circulation pump 4 at a low speed to reduce the amount of injection per unit time, so that the injection cold water flows down to the lower part of the heater. To prevent Next, if the comparison result in the temperature difference comparison unit is equal to or less than a predetermined temperature difference (for example, 30 ° C.), the pump drive control unit 16
Accordingly, by driving the circulation pump 4 at a high speed, the temperature of the injected water can be made as close as possible to the temperature of the boiling water when the boiling is completed, so that desired high-temperature water can be stored from the upper portion to the lower portion of the hot water storage tank 1. As shown in FIG. 5, when the heating amount is the same, the temperature difference is large when the flow rate is small (dT1 for Q1),
If the flow rate is large, the characteristic that the temperature difference is small (dT2 for Q2) is well known. Therefore, as shown in FIG. 6, when the flow rate is small, it is desirable to reach the lower part of the hot water tank at the completion of boiling, as indicated by the dotted line. However, if the flow rate is increased, desired hot water can be stored from the upper part to the lower part of the hot water storage tank as indicated by the solid line. Conversely, if the circulation pump 4 is rotated at a high speed in order to increase the flow rate, noise increases. Usually, as shown in FIG. 6, a high flow rate is required for a short time near the completion of boiling, so that the operation can be performed with low noise for most of the operation time.

As described above, the present embodiment has the pump inlet temperature detecting means 9 for detecting the temperature at the inlet of the circulating pump 4, and the temperature at the inlet of the circulating pump 4 and the boiling temperature which is the set boiling temperature. A pump drive control unit 16 is provided that drives the circulation pump 4 at a low speed when the difference from the temperature detected by the hot water temperature detecting means 8 is equal to or more than a predetermined temperature difference, and at a high speed when the difference is less than the predetermined temperature difference. Accordingly, when the difference between the temperature at the inlet of the circulation pump 4 and the set temperature for boiling is large, the speed is reduced to reduce the injection amount per unit time, thereby preventing the injection cold water from flowing down to the lower portion of the heater 2. When the difference between the temperature at the inlet of the circulation pump 4 and the set temperature for boiling is small, the speed is increased to increase the amount of injection per unit time, and when the boiling is completed, the temperature of the injected water is brought as close as possible to the temperature of the boiling water. Desired high-temperature hot water from the top to the bottom of hot water storage tank 1 It is possible to store.

The high flow rate is required for a short time near the completion of boiling, so that the operation can be performed with low noise for most of the operation time.

In this embodiment, the circulation pump 4
The pump inlet temperature detecting means 9 for detecting the temperature at the inlet of the circulating pump is configured to be attached to the circulation path of the circulating pump inlet.
The same effect can be obtained even if the structure is attached to the can wall or the inside of the lower part of the hot water tank.

(Embodiment 3) FIG. 7 is a configuration diagram of a hot water storage type electric water heater according to a third embodiment of the present invention, and FIG. 8 is an explanatory diagram of a temperature change in an upper portion and a lower portion of a hot water tank before and after the heater is stopped in the third embodiment. It is. In FIG. 7, reference numeral 17 denotes a heater driving unit, 18 denotes a temperature comparing unit which compares the detected temperature of the hot water temperature detecting means 8 after the heater power is stopped by the heater driving unit 17 and a predetermined temperature, 19 Is a timer that counts a preset time after the heater drive unit 17 stops energizing the heater, and 20 has a pump stop control unit having a temperature comparison unit 18 and a timer 19, which is different from the configuration of the first embodiment. The difference is that a pump stop control unit 20 having a temperature comparison unit 18 and a timer 19 is provided.

The operation and operation of the hot water storage type electric water heater configured as described above will be described below.

First, upon detecting that the boiling water temperature detecting means 8 has reached the set boiling temperature (for example, 91 ° C.), the heater driving unit 17 stops the energization of the heater 2 and receives the heater stop signal. Then, the timer 19 starts counting, and the temperature comparison unit 18 compares the detected temperature of the boiling water temperature detection means 8 with a predetermined temperature. When the temperature detected by the boiling water temperature detecting means 8 decreases to a predetermined temperature or when the count of the timer 19 elapses a predetermined time, the pump stop control unit 20 drives the circulation pump 4. To stop. As shown in FIG. 8, the temperature change of the upper and lower portions of the hot water storage tank 1 before and after the heater is stopped. A so-called excessive temperature rise phenomenon occurs in which the temperature is further increased from the temperature when the heater is stopped due to the influence of heat. Conversely, when the circulation pump is driven after the heater is stopped, the relatively low-temperature hot water in the lower part of the hot water tank 1 is injected. As shown by the solid line, the temperature of the upper part of the hot water tank is lower than the temperature at the time when the heater is stopped. However, it can be seen that the temperature at the lower part of the hot water tank rises.

As described above, in the present embodiment, after the heater power is stopped, the temperature detected by the boiling water temperature detecting means 8 decreases to a predetermined temperature set in advance, or stops after a predetermined time elapses. The pump stop control unit 20 is provided to continue the pump drive after stopping the heater power supply, move the heater residual heat to the lower part of the hot water storage tank 1, prevent the temperature from rising excessively, and maintain the temperature difference between the upper part and the lower part of the hot water storage tank 1. It is possible to store a desired high-temperature hot water with a small amount.

[0032]

As described above, claims 1, 2, 3, 4,
According to the invention described in 5, the desired high-temperature hot water can be stored from the upper portion of the hot water storage tank from the middle of the boiling to the completion of the boiling. In addition, heat loss from the circulation path can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a hot-water storage type electric water heater in Embodiment 1 of the present invention.

FIG. 2 is a top configuration diagram of a hot-water storage type electric water heater in Embodiment 1 of the present invention.

FIG. 3 is a temperature distribution diagram in a hot water storage tank of the hot water storage type electric water heater according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of a hot-water storage type electric water heater in Embodiment 2 of the present invention.

FIG. 5 is an explanatory diagram of a circulation flow rate and a temperature difference in Embodiment 2 of the present invention.

FIG. 6 is a temperature distribution diagram in a hot water storage tank of a hot water storage type electric water heater according to a second embodiment of the present invention.

FIG. 7 is a configuration diagram of a hot-water storage type electric water heater according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram of a temperature change in an upper part and a lower part of a hot water tank before and after a heater is stopped in a third embodiment of the present invention.

FIG. 9 is a configuration diagram of a conventional hot water storage type electric water heater.

FIG. 10 is a temperature distribution diagram in a hot water storage tank of a conventional hot water storage type electric water heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot water storage tank 2 Heater 3 Circulation path 4 Circulation pump 8 Hot water temperature detection means 9 Pump inlet temperature detection means 10 Water injection pipe 11 Water injection port 16 Pump drive control unit 20 Pump stop control unit

Claims (5)

[Claims] 1. A water supply having a heater at an upper part of a hot water storage tank and a boiling water temperature detecting means at an upper part of the heater, and having a water injection port opened from a lower part of the hot water storage tank so as to face an inner wall of the upper part of the hot water storage tank via a circulation pump. Hot water storage type water heater with a circulation path connected to the pipe. 2. A hot water storage type electric water heater according to claim 1, further comprising a boiling hot water temperature detecting means near the opening of the water inlet above the hot water storage tank. 3. The hot water storage type electric water heater according to claim 1, wherein a water injection pipe inside the hot water storage tank is replaceable. 4. The circulation pump has a variable speed of low speed and high speed,
A pump inlet temperature detecting means for detecting a temperature of the circulating pump inlet; when a difference between the temperature of the circulating pump inlet and the set boiling temperature is equal to or more than a predetermined temperature difference, the speed is reduced to a predetermined value; 2. The hot water storage type electric water heater according to claim 1, further comprising a pump drive control unit that drives the circulation pump at a high speed in the following cases. 5. A water injection port provided with a heater at an upper portion of a hot water storage tank and a boiling water temperature detecting means at an upper portion of the heater, and having a water injection port opened from a lower portion of the hot water storage tank to face an inner wall of the hot water storage tank via a circulation pump. A pump stop control unit that includes a circulation path connected to the pipe, and after the heater energization is stopped, the detection temperature of the boiling water temperature detection unit decreases to a predetermined temperature set in advance or stops after a predetermined time has elapsed. Hot water storage type electric water heater equipped.