JPH0443185B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hot water mixing type hot water supply control device, and improves hot water output characteristics by controlling the hot water side temperature so that the hot water mixing ratio is always constant. The present invention relates to a scale and a hot water supply control device that is easy to use.

(Prior Art) Generally, in hot water mixing type hot water supply control devices that mix water and hot water to obtain a desired hot water outlet temperature, a method is adopted in which the hot water side outlet temperature is set to a constant high temperature. (Refer to Japanese Utility Model Application Publication No. 58-120443.) In such conventional methods, feedback control is adopted in which the hot water mixing valve is controlled while comparing the mixed hot water temperature TM and the set temperature TS. When TM changes, the hot water mixing valve is driven to match it with the set temperature TS.

(Problems to be Solved by the Invention) In this conventional method of setting the hot water outlet temperature at a constant high temperature, the hot water mixing ratio changes every time the set temperature changes.

In other words, the relationship between the hot water temperature from the heat exchanger (= hot water side hot water temperature) TH, the inlet water temperature TC, the hot water side flow rate QH, the mixed hot water temperature TM, the hot water output amount QM, and the heating capacity G is as follows: G = (TH- TC)・QH=(TM−TC)・QM……(1) QM=QH+QC……(2) QH/QM=TM−TC/TH−TC……(3) The following formula holds true.

For example, in each equation (1), (2), and (3) above, the hot water outlet temperature
TH=80℃, set temperature TS=TM=38℃, water inlet temperature
Substituting TC = 15°C and hot water flow rate QM = 10/min, the hot water side flow rate QH = 3.54/min and the bypass water flow rate QC = 6.46/min.
Also, when the set temperature TS=TM is changed to 45℃,
Hot water side flow rate QH = 4.62/min, bypass water flow rate QC =
It becomes 5.38/min. In other words, the hot water mixing ratio changes as follows: when TS = 38°C, QH/QM = 0.354, and when TS = 45°C, QH/QM = 0.462.

When the set temperature TS changes, the mixing ratio must also be changed, but since the mixing ratio is controlled using feedback control, a control delay occurs, causing a delay in the response of the hot water mixing valve, and furthermore, when the ratio is changed, the response of the hot water mixing valve is delayed. Therefore, there are problems in that the reaction is slow, such as requiring control of the hot water mixing valve that takes a long time to drive, and the hot water output characteristics are deteriorated.

The present invention was made in consideration of the above-mentioned circumstances, and by controlling the hot water temperature so that the hot water mixing ratio is always constant, the hot water tapping characteristics are improved and the ease of use is improved. The object of the present invention is to provide a hot water mixing control device for a water heater.

(Means for Solving the Problems) In order to achieve the above object, the hot water supply control device according to the present invention includes a water temperature detector that detects the incoming water temperature, a temperature setting device that sets the mixed outlet temperature, and a water temperature A hot water side temperature setting means for receiving the outputs of the detector and the temperature setting device and setting a hot water side set temperature that has a predetermined functional relationship with these, the set hot water side outlet temperature, the signal of the water temperature detector, and the heating path. The heating device is characterized by being provided with a capacity control device that controls the amount of heat generated by the heating device based on a signal from a flow rate detector provided in the heating device.

With this configuration, when changing the set temperature TS or the inlet water temperature TC, the hot water side temperature can be controlled to the desired outlet temperature TS by changing the hot water side temperature while keeping the hot water mixture ratio constant. It is possible to prevent deterioration of hot water output characteristics due to response delay of the mixing valve.

(Embodiment) The drawing shows an embodiment of the present invention, in which reference numeral 1 denotes a hot water supply circuit comprising a heating path 3 passing through a heat exchanger 2 and a bypass path 4 parallel to the heat exchanger 2. 5 is a heating device such as a burner that heats the heat exchanger 2; 6 is a capacity control device such as a gas proportional valve that controls the amount of heat generated by the heating device 5; 7 is a water temperature detector provided on the water inlet side of the hot water supply circuit 1 to detect the temperature of the water supply;
is a hot water temperature detector installed on the hot water outlet side of the hot water supply circuit 1 to detect the mixed hot water temperature. A flow rate detector 9 detects the flow rate to the heat exchanger 2, and is arranged in the heating path 3. Reference numeral 10 denotes a water flow control valve that is provided in the bypass passage 4 and controls the flow of bypass water. 11 is a temperature setting device. 12 is a control circuit section, which includes a water temperature detector 7;
, a heat amount control unit 13 that operates the capacity control device 6 based on the signals from the flow rate detector 9 and the temperature setting device 11; and a hot water side that receives the outputs of the water temperature detector 7 and the temperature setting device 11 and has a predetermined functional relationship therewith. It incorporates a hot water side temperature setting means 15 for setting a set temperature, and a water flow control section 14 for operating a water flow control valve 10 based on signals from the temperature setting device 11 and hot water temperature detector 8.

The control circuit section 12 sets the hot water side temperature set temperature TS' based on the set temperature TS of the temperature setting device 11 and the incoming water temperature TC detected by the water temperature detector 7, for example, based on the following equation (4), The hot water outlet temperature TH on the hot water side is set to this set value.
The opening degree of the gas proportional valve 6 is controlled so that the values match.

TS'=f(TS, TC) =K・TS+(1−K)・TC (4) The operation in the above configuration will be explained. The supplied water is divided into a heating path 3 and a bypass path 4. In the heating path 3, the water temperature detector 7 detects the inlet water temperature TC, the flow rate detector 9 detects the flow rate QH, and sends a signal to the heat amount control section 13. The heat amount control unit 13 calculates the amount of gas G to be combusted by the heating device 5 from these data together with the signal from the temperature setting device 8, and sends a signal to the capacity control device 6 to cause the gas amount to flow. Then, the water flowing through the heating path 3 is heated by the heat exchanger 2, and in anticipation of the cold water mixture, the hot water temperature is slightly higher than the set temperature TS.
Become TH. That is, the gas amount G is calculated from the above equation (1) by setting TH=TS', and heating is performed through feedforward control. After that, it is mixed with cold water, but in order to correct errors caused by variations in equipment, the hot water temperature TM after mixing is detected by the hot water temperature detector 8, and the water flow control unit 14 is operated by a water flow control valve so that TM=TS. The opening degree of 10 may be calculated and the water flow control valve 10 may be operated.

By the way, suppose that the set temperature TS is changed during hot water supply. As mentioned above, the set temperature TS' on the hot water side is determined by equation (4), and now TH=TS', so equation (4) is TH=K・TS+(1−K)・TC... (5) and TM=TS, so TH in equation (3) becomes
Substituting equation (5) and setting TM to TS, equation (3) becomes QH/QM=TS−TC/K・TS+(1−K)・TC−TC=1/K (constant), and the setting The mixing ratio of hot water and water will always remain constant regardless of the temperature. Also, this is the water inlet temperature TC
Similarly, it remains constant even if changes.

Note that an appropriate value exceeding 1 can be selected as the value of K.

(Effects of the Invention) As described above, according to the present invention, the set temperature on the hot water side is made a function of the set temperature and the inlet water temperature, and even if the set temperature and the inlet water temperature change, the hot water mixing ratio is kept constant, and the capacity is increased. By configuring the hot water side outlet temperature to be controlled by the feed forward control of the control device, even if the set temperature is changed, the capacity control side with a quick response time will respond, and the hot water mixing ratio with a slow response time will be adjusted. It is possible to control the mixed hot water temperature without any control delay, improve the hot water tap characteristics, and increase usability.

[Brief explanation of the drawing]

FIG. 1 is an overall circuit diagram of the present invention. FIG. 2 is a block circuit diagram of the control circuit section. 1...Hot water supply circuit, 2...Heat exchanger, 3...Heating path, 4...Bypass path, 5...Heating device, 6...
Capacity control device, 7...Water temperature detector, 8...Hot water temperature detector, 9...Flow rate detector, 10...Water flow control valve,
11...Temperature setting device, 12...Control circuit section, 13
...Hot water side temperature setting means.

Claims (1)

[Claims] 1. A hot water supply circuit composed of a heating path passing through a heat exchanger and a bypass path parallel to the heat exchanger, a heating device that heats the heat exchanger, a water temperature detector that detects the temperature of incoming water, and a mixed hot water outlet. a temperature setting device for setting the temperature, a hot water side temperature setting means for receiving the outputs of the water temperature detector and the temperature setting device and setting a hot water side set temperature that has a predetermined functional relationship with these, and a hot water side temperature setting device that sets the set hot water side temperature. and a capacity control device for controlling the amount of heat generated by the heating device based on a signal from the water temperature detector and a signal from a flow rate detector provided in the heating path.