JP2007170753A - Water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water heater capable of preventing a hunting phenomenon in a low flow rate, and preventing the supply of hot water of a high temperature. <P>SOLUTION: A control device 200 controls a mixing valve 16 with a mixing ratio in which an opening at a hot water side is fixed to a prescribed opening, when a flow rate detected by a flow rate counter 72 is small, the mixing valve 16 is controlled to keep the mixing ratio same as that in detecting a value smaller than a prescribed value for a prescribed time from the detection of the value less than the prescribed value, when the flow rate detected by the flow rate counter 72 is changed to a value smaller than the prescribed value, when the mixing valve 16 is controlled by PID control, and further the mixing valve 16 is controlled to the mixing ratio in which an opening at the hot water side is fixed to the prescribed opening after the lapse of a prescribed time. Thus the hunting phenomenon can be prevented, and the supply of hot water of a high temperature can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hot water supply apparatus, and more particularly, to a hot water storage type hot water supply apparatus provided with mixing means for hot water and water.

  Conventionally, as this type of hot water supply device, as shown in Patent Document 1, for example, a hot water supply device that generates hot water by exchanging heat between a heat storage fluid stored in a hot water storage tank and water with a heat exchanger to supply hot water It has been known. In this apparatus, mixing means for adjusting the hot water supply temperature of the hot water exchanged by the heat exchanger is provided, and the mixing means is controlled so that the hot water supply temperature becomes the hot water supply set temperature.

  More specifically, there are provided hot water amount detection means for detecting the flow rate through the hot water passage of the heat exchanger and hot water supply temperature detection means for detecting the hot water temperature discharged from the mixing means. Then, the mixing means is subjected to PID control (feedback control) at a mixing ratio at which the hot water temperature detected by the hot water supply temperature detecting means becomes the hot water supply set temperature.

  Here, the PID control (feedback control) is a control for changing the mixing ratio of the mixing means every time the tapping amount detecting means detects a constant flow rate (for example, about 0.1 liter). Even if the flow rate through the hot water passage changes from a small flow rate (for example, about 1.5 liters / minute) to a large flow rate (for example, about 15 liters / minute), temperature control to the hot water supply set temperature with the same rise time It can be performed.

Further, in this type of mixing means, for example, as shown in Patent Document 2, the mixing ratio of the mixing means is controlled according to the hot water supply set temperature when hot water is supplied, and the mixing ratio of the mixing means is set for a predetermined time when hot water is stopped. The mixing means is controlled to a mixing ratio that keeps the mixing ratio in the state when hot water supply is stopped and closes the hot water passage side of the mixing means after a predetermined time has elapsed. That is, control is performed to maintain the mixing ratio at the time of hot water supply stop so as to be able to respond quickly when hot water is supplied again within a predetermined time after the stop of hot water supply.
JP-A-14-122352 Japanese Patent Publication No. 7-72620

  However, in the above-mentioned document 1, when the flow rate through the hot water passage is reduced to a region less than a small flow rate (for example, about 1.5 liters / minute), the detection accuracy of the output pulse itself of the hot water detection means decreases, and PID There is a problem that a hunting phenomenon occurs in the hot water supply temperature at which the control (feedback control) becomes unstable and the mixing means is discharged.

  Moreover, in the said literature 2, when a flow volume falls further, for example, it will become an area | region below a micro flow volume (for example, about 0.5 liter / min), the amount-of-hot water detection means will be in a state which cannot be detected. Here, when hot water is supplied at such an extremely small flow rate within a predetermined time after the hot water supply is stopped, in this case, the amount of hot water detection means is detected as a hot water supply stop state, and the mixing ratio of the state when the hot water supply is stopped The state held in the state is continued, and an extremely small flow rate passes therethrough.

  In other words, in the mixing means for PID control in this case, when the temperature is generally less than a small flow rate (for example, about 1.5 liters / minute), the hot water supply temperature for hot water rises to the high temperature side (for example, JP 2003-83614 gazette based on FIG. 3). Accordingly, there is a problem that hot water is discharged.

  In view of the above, an object of the present invention is to provide a hot water supply apparatus that can prevent a hunting phenomenon at a small flow rate and prevent high-temperature hot water.

In order to achieve the above object, the technical means described in claims 1 to 6 are employed. That is, in the first aspect of the present invention, the internal water is heated by the heating means (2) and stored as hot water inside the hot water storage tank (1), and the water supply path for sending water to the hot water storage tank (1) ( 12), a hot water supply path (14) for sending hot water stored in the hot water storage tank (1), a bypass circuit (15) branched from the water supply path (12) and bypassing the hot water storage tank (1), and a hot water supply path ( 14) and the mixed hot water path (17) where the bypass circuit (15) merges, and the mixed hot water path (17) is provided, detects the flow rate of the mixed hot water passing through the mixed hot water path (17), and mixes hot water. The hot water supply amount detection means (72) for detecting the presence or absence of the supply of mixed hot water passing through the route (17), the hot water supply route (14), and the bypass circuit (15) are provided at the junction point, and the hot water supply route (14) is provided. Between passing hot water and water passing through the bypass circuit (15). The mixing means (16) for controlling the combined ratio by adjusting the opening degree of each path (14, 15) and the downstream of the mixing means (16) are provided, and the mixing means (16) is discharged. Hot water supply temperature detection means (71) for detecting the hot water supply temperature, and control means for controlling the mixing ratio of the mixing means (16) by PID control in which the hot water supply temperature detected by the hot water supply temperature detection means (71) becomes the hot water supply set temperature. (200)
The control means (200) is slower than the mixing ratio in which the opening degree on the hot water supply path (14) side is fixed at a predetermined opening degree or the PID control when the flow rate detected by the tapping amount detection means (72) is small. It is characterized in that the mixing means (16) is controlled to any one of the mixing ratios by the feedback control with the control time interval of the predetermined time by the gain.

  According to the present invention, when the flow rate is small (for example, less than about 1.5 liters / minute), the hot water side opening is controlled to a mixing ratio that is fixed, so that the hot water supply temperature is stabilized and the hunting phenomenon is prevented. It can be prevented.

  In addition, without using PID control for controlling the mixing ratio every time a constant flow rate is detected, feedback control is performed with a slower gain than that for a control time interval of a predetermined time, so that the hot water supply temperature is stabilized and the hunting phenomenon Can be prevented.

  In the invention described in claim 2, when the mixing means (16) is controlled by PID control, the control means (200) changes the flow rate detected by the tapping amount detection means (72) to less than a predetermined value. The mixing means (16) is controlled so that the predetermined time after detecting less than the predetermined value is maintained so that the mixing ratio when the less than predetermined value is detected or the water ratio larger than the mixing ratio is maintained. After the predetermined time has elapsed, either the mixing ratio at which the opening on the hot water supply path (14) side is fixed to the predetermined opening or the mixing ratio by feedback control with a gain slower than the PID control and the control time interval of the predetermined time. The mixing means (16) is controlled to one of the mixing ratios.

  According to the present invention, when there is reheating hot water whose flow rate increases again within the predetermined time, the temperature adjustment can be quickly coped with. However, when the state of low flow rate is hot water supply that continues for a predetermined time, the hot water supply temperature can be stabilized after the predetermined time has elapsed.

  In the third aspect of the present invention, when the mixing means (16) is controlled by PID control, the control means (200) determines that the flow rate detected by the tapping amount detection means (72) is less than a predetermined value. Mixing ratio at which the opening on the hot water supply path (14) side is fixed to a predetermined opening when detected continuously for a period, or a mixing ratio by feedback control with a control time interval of a predetermined time with a gain slower than PID control The mixing means (16) is controlled to any one of the mixing ratios.

  According to the present invention, when hot water is being supplied, when the flow rate changes to a small side (for example, less than about 1.5 liters / minute), the hot water side opening degree is set to a fixed mixing ratio or a predetermined value. By performing feedback control with the time control time interval, the hunting phenomenon can be prevented by stabilizing the hot water supply temperature.

  In the invention according to claim 4, when the hot water temperature detected by the hot water temperature detecting means (71) is equal to or higher than a predetermined value, the control means (200) closes the opening degree on the hot water supply path (14) side. The mixing means (16) is controlled to the mixing ratio.

  According to the present invention, the flow rate is small particularly in the case of either the predetermined time when the opening on the hot water supply path (14) side is open or the mixing ratio at which the opening is fixed at the predetermined opening (for example, , Less than about 1.5 liters / minute), for example, if the flow rate is less than a minute flow rate (for example, about 0.5 liters / minute), the amount of hot water detection means (72) is undetectable. However, by monitoring the hot water supply temperature, hot hot water can be prevented from being discharged.

  In the fifth aspect of the present invention, the control means (200) determines the predetermined time after detecting the hot water supply stop when the hot water detection means (72) detects the hot water supply stop through the mixed hot water path (17). The mixing means (16) is controlled so as to maintain the mixing ratio when the hot water supply stop is detected or the mixing ratio on the water side is larger than the mixing ratio, and the opening on the hot water supply path (14) side after a predetermined time has elapsed. It is characterized in that the mixing means (16) is controlled to a mixing ratio at which is blocked.

  According to the present invention, when the hot water is re-supplied within the predetermined time, the temperature can be quickly adjusted.

  In the invention according to claim 6, either or both of the hot water supply path (14) and the bypass circuit (15) are provided in the mixing means (16) via a check valve (23) that prevents backflow. It is characterized by having. According to the present invention, when the hot water supply is stopped within the predetermined time when the opening on the hot water supply path (14) side is open, the hot water supply path (14) and the bypass path (15) in the mixing means (16). The movement of hot water and water by natural convection with can be prohibited.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment mentioned later.

(First embodiment)
Hereinafter, a hot water supply apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic diagram illustrating a schematic configuration of a hot water supply apparatus according to the present embodiment, and FIG. 2 is a flowchart illustrating a temperature control process of the control apparatus 200. FIG. 3 is a transition diagram of a control mode for controlling the mixing ratio of the mixing valve 16 with respect to the detection value detected by the flow counter 72.

  As shown in FIG. 1, the hot water supply apparatus of the present embodiment includes a hot water storage tank 1, an introduction pipe 12 that is a water supply path, a discharge pipe 14 that is a hot water supply path, a pipe 17 that is a mixed hot water path, and a water supply pipe 15 that is a bypass path. The mixing valve 16 is a mixing unit, the heat pump unit 2 is a heating unit, and the control device 200 is a control unit.

  Reference numeral 1 denotes a metal (for example, stainless steel) hot water storage tank having excellent corrosion resistance, and a heat insulating material (not shown) is disposed on the outer peripheral portion, so that hot water for hot water supply can be kept warm for a long time. ing. The hot water storage tank 1 has a vertically long shape, and an introduction port 11 is provided on the bottom surface. An introduction pipe 12 that is a water supply path for introducing tap water into the hot water storage tank 1 is connected to the introduction port 11.

  The introduction pipe 12 is provided with a water supply thermistor 21 as temperature detection means, and outputs temperature information in the introduction pipe 12 to the control device 200 described later. The introduction pipe 12 is provided with a pressure reducing valve 51 that adjusts the water pressure of the introduced tap water to a predetermined pressure. The downstream side of the position where the water supply thermistor 21 and the pressure reducing valve 51 of the introduction pipe 12 are provided and the mixing valve 16 which is a mixing means described later are connected by a water supply pipe 15 which is a bypass path.

  On the other hand, a lead-out port 13 is provided at the top of the hot water storage tank 1, and a lead-out pipe 14, which is a hot water supply path for leading out hot water in the hot water storage tank 1, is connected to the lead-out port 13. A discharge pipe 52 provided with a relief valve 53 is connected in the course of the outlet pipe 14, and when the pressure in the hot water storage tank 1 rises above a predetermined pressure, the hot water in the hot water storage tank 1 is discharged to the outside. It is discharged so as not to damage the hot water storage tank 1 or the like.

  Reference numeral 16 denotes a mixing valve, which is a mixing means, and is arranged at the junction of the outlet pipe 14 and the water supply pipe 15. The mixing valve 16 is adjusted from the outlet pipe 14 by adjusting an opening area ratio (a ratio of a hot water side opening degree communicating with the outlet pipe 14 and a water side opening degree communicating with the water supply pipe 15) which is a mixing ratio. The mixing ratio between the hot water and the tap water from the water supply pipe 15 can be adjusted.

  The mixing valve 16 is an electric valve that adjusts the opening degree of each path by driving a valve body by a drive source such as a servo motor, and is operated by a control signal from a control device 200 described later and controls the operating state. The data is output to the apparatus 200.

  A check valve 23 for preventing a backflow is provided on the downstream side of each of the outlet pipe 14 and the water supply pipe 15. When the hot water supply is stopped while the opening degree of the mixing valve 16 is maintained, the check valve 23 is heated by natural convection between the hot water in the outlet pipe 14 and the water in the water supply pipe 15 through the mixing valve 16. The water supply pipe 15 and the water are prevented from moving to the outlet pipe 14.

  A pipe 17 that is a mixed hot water path to a faucet, a shower, a bath, or the like is connected to the outlet side of the mixing valve 16. The pipe 17 is provided with a hot water supply thermistor 71 that is a hot water supply temperature detection means and a flow rate counter 72 that is a hot water amount detection means. The hot water supply thermistor 71 is temperature information in the pipe 17, and the flow rate counter 72 is a flow rate in the pipe 17. The information is output to the control device 200 described later.

  The flow rate counter 72 detects the flow rate of the mixed hot water flowing through the pipe 17 and detects the presence or absence of supply of the mixed hot water flowing through the pipe 17 based on the flow rate. The flow rate information in the pipe 17 is used as the speed of the pulse signal. To output to the control device 200.

  For example, when the pulse signal from the flow rate counter 72 is input at 0 pps (plus / sec), the control device 200 determines that the hot water supply is stopped. If the pulse signal is 1 pps or more, it is determined that hot water is used in any of a faucet, shower, bath, and the like.

  By the way, the temperature control of the mixed hot water flowing through the pipe 17 is controlled by the control device 200 at the mixing ratio of the mixing valve 16. In other words, the control device 200 first adjusts the opening area ratio of the mixing valve 16 based on the temperature information from the water supply thermistor 21 and the temperature information from the hot water thermistor 32 described later according to the hot water supply set temperature. Then, based on the hot water supply temperature information from the hot water supply thermistor 71, the opening area ratio, which is the mixing ratio of the mixing valve 16, is finely adjusted by PID control (feedback control) so that the hot water supply temperature becomes the hot water supply set temperature. It comes to control.

  Here, FF (feed forward) control calculates the opening area ratio of the mixing valve 16 from the temperature information from the feed water thermistor 21 and the temperature information from the hot water thermistor 32 described later according to the hot water supply set temperature, and this area. The mixing ratio is set as the initial opening, and feedforward control is performed for a while. More specifically, every time the flow rate counter 72 detects a constant flow rate (for example, about 0.1 liter), the following PID control (feedback control) is performed.

Hn = Hn-1 + Kp (En-En-1) + Ki * En + Kd (En-2En-1 + En-2) where Hn: control input value, En, En-1, En-2 ... difference from target temperature, Kp ... Proportional coefficient, Ki ... integral coefficient, Kd ... differential coefficient When PID control is performed each time a constant flow rate is detected in this way, the control time interval (interval) can be changed according to the magnitude of the flow rate. Thereby, in the case of steady hot water supply after the end of the initial state, the hot water supply temperature is set at the same rise time from a medium flow rate (for example, 1.5 liters / minute) to a large flow rate (for example, 15 liters / minute). Temperature control can be performed.

  Therefore, in the present invention, the PID control (feedback control) is divided into two stages of the control constants (Kp, Ki, Kd, etc.), for example, PID-1 control and PID-2 control.

  Here, the PID-1 control has a smaller control constant (Kp, Ki, Kd, etc.) than the PID-2 control, and the flow rate is medium (for example, 1, 5 to 4.0 liters / minute). PID-1 control is performed at this time, and PID-2 control is performed when the medium flow rate is exceeded. Further, when the flow rate is smaller than this medium flow rate (for example, less than 1.5 liters / minute), the mixing valve 16 is controlled to a mixing ratio that fixes the opening degree on the hot water side to a predetermined opening degree (about this) , Described later).

  A suction port 18 for sucking water in the hot water storage tank 1 is provided in the lower part of the hot water storage tank 1, and a discharge port 19 for discharging hot water into the hot water storage tank 1 is provided on the upper side surface of the hot water storage tank 1. Is provided. The suction port 18 and the discharge port 19 are connected by a circulation circuit 20, and a part of the circulation circuit 20 is disposed in the heat pump unit 2.

  A heat exchanger (not shown) is provided in a portion of the circulation circuit 20 disposed in the heat pump unit 2 and heats water in the hot water storage tank 1 sucked from the suction port 18 by heat exchange with a high-temperature refrigerant. The water in the hot water storage tank 1 can be boiled up by returning it from the discharge port 19 into the hot water storage tank 1.

  The heat pump unit 2 is a heating unit in the present embodiment. The heat pump unit 2 is operated by a control signal from a control device 200 described later, and outputs an operation state to the control device 200.

  Further, a hot water thermistor 32 for detecting the water temperature in the upper part of the hot water storage tank 1 is provided on the upper outer wall surface of the hot water storage tank 1, and the temperature information of the water derived from the outlet 13 is output to the control device 200 described later. It is supposed to be.

  Further, a plurality of (six in this example) water level thermistors 33 are arranged on the outer wall surface of the hot water storage tank 1 at almost equal intervals in the vertical direction, and temperature information at each water level filled in the hot water storage tank 1 is obtained. Is output to the control device 200 described later. Therefore, the control device 200 can detect the boundary position between the hot water heated in the upper part of the hot water tank 1 and the water before being heated in the lower part of the hot water tank 1 based on the temperature information from the water level thermistor 33. It has become.

  Reference numeral 200 denotes a control device which is a control means, which includes temperature information from each of the thermistors 21, 32, 33, 71, flow information from the flow counter 72, and signals from operation switches provided on an operation panel (not shown). Based on the procedure described later, the heat pump unit 2, the mixing valve 16 and the like are controlled.

  An operation panel (not shown) is installed in the vicinity of a place where hot water is used such as in a bathroom or kitchen, and the operation panel other than the operation panel is installed in a suitable place such as outdoors.

  Next, the operation of the hot water supply apparatus having the above configuration will be described with reference to FIGS. When a power switch (not shown) of the hot water supply device is turned on, as shown in FIG. 2, in step 210, control device 200 starts temperature control. At this time, the opening of the mixing valve 16 on the hot water side is set to 0% (the hot water side is closed), and the mixing valve 16 is controlled so that the opening on the water side is set to 100%.

  At this time, the heat pump unit 2 is appropriately operated to heat the water in the hot water storage tank 1 based on temperature information from each thermistor provided in the hot water storage tank 1 or time information set by an operation panel (not shown). And hot water (for example, 85 ° C. hot water).

  In step 220, it is determined whether or not the flow rate information detected by the flow rate counter 72 is 0 pps. Here, it is determined whether or not the faucet or the like is opened and hot water supply via the pipe 17 is started. Specifically, if the flow rate information is 1 pps or more, it is determined that the hot water supply is started. 230. If the flow rate information is 0 pps, the hot water supply is determined to be stopped and is on standby.

  First, at step 230, the hot water side opening of the mixing valve 16 is fixed at, for example, 20% (water side fixed at 80%). In step 260, it is determined whether the flow rate information is 14 pps (about 2 liters / minute) or more. Here, it is determined whether or not the flow rate of hot water supply is a small flow rate. If the flow rate is small, the flow returns to step 230, and the hot water side opening is kept fixed at 20%. If it is a small flow rate or more, the process proceeds to step 270.

  In step 240 and step 250, as shown in FIG. 3, the flow rate information detected by the flow rate counter 72 and the hot water supply thermistor when the hot water side opening of the mixing valve 16 is fixed at 20%. It is a determination means for monitoring the hot water temperature information detected at 71. At this time, if the flow rate information becomes 0 pps, it is determined that the hot water supply has been stopped, and the routine returns to step 210 to close the opening on the hot water side. If the hot water supply temperature information is 65 ° C. or higher and continuous for 10 seconds, the process returns to step 210 to close the hot water side opening.

  If the flow rate information is 14 pps (about 2 liters / minute) or more in step 260 when the hot water side opening is fixed at 20%, in step 270, the first stage of normal control. PID-1 control is performed. More specifically, based on the hot water supply temperature information from the hot water supply thermistor 71, the mixing ratio of the mixing valve 16 is feedback controlled so that the hot water supply temperature becomes the hot water supply set temperature.

  In addition, when performing PID-1 control, specifically, it is performed when the flow rate is within a range of a medium flow rate (for example, about 1.5 to 4 liters / minute). That is, the flow rate information is monitored at step 280 and step 290, and PID-1 control is performed when it is 10 pps (about 1.5 liters / minute) or more at step 280 and less than 28 pps (about 4 liters / minute) at step 290. .

  When PID-1 control is being performed, if the flow rate information changes to a small flow rate of less than 10 pps (about 1.5 liters / minute) in step 280, the flow rate information changes in step 300. The mixing ratio of the final opening at that time or the mixing ratio on the water side larger than the mixing ratio is maintained. In step 290, when the flow rate information changes to a large flow rate of 28 pps (about 4 liters / minute) or more, the process proceeds to step 310.

  When the flow rate has changed to a small flow rate, it is determined in step 320 whether 10 minutes have passed since the final opening degree mixing ratio was maintained. If the predetermined time has elapsed, the process returns to step 230 and the hot water side opening is fixed to 20%. If it is within the predetermined time, flow information and hot water supply temperature information are obtained in steps 330 to 360. And monitor.

  In other words, when the PID-1 control is performed and the flow rate is changed to a small flow rate, each opening degree at that time is held as the final opening degree. Then, the final opening is held for a predetermined time. And if predetermined time passes, the opening degree of the hot water side will be fixed to 20%.

  In addition, if the flow rate information is 0 pps within the predetermined time, it is determined that the hot water supply has been stopped, and if the hot water supply temperature information continues, for example, at 65 ° C. or more for 10 seconds, the process returns to step 210 to return to the hot water side. Close the opening. At this time, if the hot water supply temperature information is less than 65 ° C., it waits until a predetermined time is reached.

  In step 350, when the flow rate information recovers to 14 pps or more, the process returns to step 270 to perform PID-1 control. If the flow rate information is less than 14 pps and the flow rate information is 1 to 9 pps for 5 seconds in step 360, the process returns to step 230 and the hot water side opening is fixed at 20%.

  On the other hand, when PID-1 control is being performed, if the flow rate information changes to a large flow rate of 28 pps (about 4 liters / minute) or more in step 290, FF (feed forward) control is performed in step 310. I do. In step 320, the PID-2 control in the second stage of the normal control is performed.

  Then, when this PID-2 control is performed, the flow rate information is monitored at step 380. Here, it is determined whether or not the flow rate information is less than 24 pps (about 3.5 liters / minute). That is, when PID-2 control is performed, if the flow rate information is less than 24 pps (about 3.5 liters / minute), the process returns to step 270 to perform PID-1 control and 24 pps (about 3.5 liters). / Min), the PID-2 control is continued.

  By performing such control, the mixing ratio of the mixing valve 16 can be controlled based on the flow rate information detected by the flow rate counter 72. Incidentally, as shown in FIG. 3, when the flow rate information is 24 pps (about 3.5 liters / minute) or more, temperature control is performed by PID-2 control.

  When the flow rate information is 10 (about 1.5 liters / minute) to 28 (about 4 liters / minute) pps, temperature control by PID-1 control is performed. When the flow rate information is less than 14 (about 2 liters / minute) pps, temperature control is performed by a mixing ratio in which the opening degree on the hot water side is fixed at 20%.

  Further, when the PID-1 control is performed, when the flow rate decreases, the opening degree is maintained at the mixing ratio when the flow rate decreases. Then, when the hot water supply temperature rises to 65 ° C. or more within a predetermined time during which the opening degree is maintained, and when the opening of the mixing valve 16 is fixed at 20%, the opening degree is closed. To be controlled.

  According to the hot water supply apparatus according to the first embodiment described above, when the flow rate detected by the flow rate counter 72 by the control device 200 is small (less than about 1.5 liters / minute), the opening degree on the hot water side is the predetermined opening degree. The mixing valve 16 is controlled to a mixing ratio fixed to.

  According to this, hot water supply temperature can be stabilized by fixing the opening degree of the hot water side to 20% without performing PID control at a small flow rate. Therefore, it is possible to prevent the occurrence of the hunting phenomenon of the hot water supply temperature, which is a drawback of PID control that becomes unstable when the flow rate is small.

  In addition, when the mixing valve 16 is controlled by PID-1 control, the control device 200 determines a predetermined value after detecting a value less than a predetermined value when the flow rate detected by the flow rate counter 72 changes below a predetermined value. For the time, the mixing valve 16 is controlled so that the mixing ratio at the time when less than a predetermined value is detected or the mixing ratio at the water side is larger than the mixing ratio is maintained. The mixing valve 16 is controlled to a mixing ratio fixed at a time.

  According to this, when there is reheating hot water whose flow rate increases again within the predetermined time, the temperature adjustment can be promptly dealt with. However, when the state of low flow rate is hot water supply that continues for a predetermined time, the hot water supply temperature can be stabilized after the predetermined time has elapsed.

  In addition, when the mixing valve 16 is controlled by PID control, the control device 200 detects the hot water side opening degree when the flow rate detected by the flow rate counter 72 continuously detects less than a predetermined value for a predetermined time. The mixing valve 16 is controlled to a mixing ratio fixed at a predetermined opening.

  According to this, when the hot water supply is performed, when the flow rate changes to a small side (for example, less than about 1.5 liters / minute), the hot water supply temperature is controlled by the mixing ratio at which the opening degree of the hot water side is fixed. Stabilization can prevent the hunting phenomenon.

  Further, when the hot water supply temperature detected by the hot water supply thermistor 71 is equal to or higher than a predetermined value, the mixing valve 16 is controlled to a mixing ratio at which the hot water opening is closed, whereby the hot water opening is predetermined. When the flow rate is small (for example, less than about 1.5 liters / minute) in either the time or the mixing ratio at which the opening is fixed at the predetermined opening, For example, when the area is less than about 0.5 liter / min), the flow rate counter 72 becomes undetectable. However, by monitoring the hot water supply temperature, hot hot water can be prevented from being discharged.

  In addition, when the flow rate counter 72 detects a hot water supply stop through the pipe 17, the control device 200 determines whether the predetermined time after detecting the hot water supply stop is equal to or higher than the mixing ratio at the time of detecting the hot water supply stop or the mixing ratio. The mixing valve 16 is controlled so that the mixing side maintains a large mixing ratio, and after a predetermined time has elapsed, the mixing valve 16 is controlled to a mixing ratio at which the opening degree of the hot water side is closed, so that hot water can be re-supplied within the predetermined time When there is, temperature control can respond quickly.

  In addition, the outlet pipe 14 and the water supply pipe 15 are provided in the mixing valve 16 via a check valve 23 for preventing a backflow, so that the hot water supply within the predetermined time when the hot water side opening degree is particularly open. When stopped, the mixing valve 16 can inhibit the movement of hot water and water by natural convection between the outlet pipe 14 and the water supply pipe 15.

(Second Embodiment)
In the first embodiment described above, when the flow rate information detected by the flow rate counter 72 is less than 14 (about 2 liters / minute) pps by the control device 200, the hot water side opening degree is fixed to 20%. The mixing valve 16 is configured to control the ratio, but not limited to this, when the flow rate information is less than 14 (about 2 liters / min) pps, control for a predetermined time with a gain slower than the PID-1 control. You may comprise so that the mixing valve 16 may be controlled to the mixing ratio by the feedback control made into a time interval.

  Specifically, as shown in FIG. 4, in step 230a, feedback (FB) control is performed at a control time interval of a predetermined time with a gain slower than PID-1 control. In other words, in PID-1 control, every time the flow rate counter 72 detects a constant flow rate (for example, about 0.1 liter), PID control (feedback control) is performed so that the hot water supply temperature becomes the set temperature. Yes.

  In the present embodiment, the accuracy is relaxed compared to the PID-1 control, and feedback (FB) control is performed at a control time interval of a predetermined time. Moreover, control constants (Kp, Ki, Kd, etc.) are set to be slower than PID-1 control.

  According to this, the hot water supply temperature can be stabilized when the flow rate is small compared to the PID-1 control. Therefore, the hunting phenomenon can be prevented by stabilizing the hot water supply temperature. In addition, about the other code | symbol shown in a figure, about the same control processing as 1st Embodiment, while attaching | subjecting the same code | symbol, description is abbreviate | omitted.

  Further, as shown in FIG. 5, according to the control according to the present embodiment, when the flow rate information is 24 pps (about 3.5 liters / minute) or more, temperature control is performed by PID-2 control. When the flow rate information is 10 (about 1.5 liters / minute) to 28 (about 4 liters / minute) pps, temperature control by PID-1 control is performed.

  When the flow rate information is less than 14 (about 2 liters / minute) pps, temperature control is performed by a mixing ratio by feedback control with a control time interval of a predetermined time with a gain slower than the PID-1 control.

(Third embodiment)
In this embodiment, as shown in FIG. 7, when the flow rate information detected by the flow rate counter 72 is 24 pps (about 3.5 liters / minute) or more, the control device 200 performs temperature control by PID-2 control. . When the flow rate information is less than 24 (about 3.5 liters / minute) pps, the mixing valve 16 is controlled to a mixing ratio by feedback control with a control time interval of a predetermined time with a gain slower than the PID-1 control. It is configured.

  When feedback control is performed, if the flow rate information is 0 pps, it is determined that hot water supply has been stopped, and the opening degree is maintained at the mixing ratio at that time. Then, when the hot water supply temperature rises to 65 ° C. or more within a predetermined time during which the opening degree is maintained, the opening degree is controlled to be closed.

  In addition, when the hot water supply temperature does not become 65 ° C. or more, for example, within a predetermined time during which the opening is maintained, the opening is controlled to be closed when the predetermined time is reached. This is specifically shown in the flowchart of FIG. 7, and can be configured by deleting steps 250 to 280, 350, and 360 described in the first and second embodiments.

  When the flow rate information is less than 24 (about 3.5 liters / minute) pps, the mixing valve 16 is controlled to a mixing ratio by feedback control with a control time interval of a predetermined time with a gain slower than the PID-1 control. By doing this, the hot water supply temperature can be stabilized when the flow rate is small, compared with the PID-1 control.

(Other embodiments)
The real value indicating the pulse signal of the flow rate information according to the above embodiment is an exemplification, and can be appropriately set according to various characteristics of the hot water supply device such as the arrangement position of the mixing valve 16, the pipe length and the handling. is there.

It is a schematic diagram which shows schematic structure of the hot water supply apparatus in 1st Embodiment of this invention. It is a flowchart which shows the control processing of the temperature control of the control apparatus 200 in 1st Embodiment of this invention. It is a transition diagram of the control form which controls the mixing ratio of the mixing valve 16 with respect to the detected value detected by the flow counter 72 in the first embodiment of the present invention. It is a flowchart which shows the control processing of the temperature control of the control apparatus 200 in 2nd Embodiment of this invention. It is a transition figure of the control form which controls the mixture ratio of the mixing valve 16 with respect to the detected value detected by the flow counter 72 in 2nd Embodiment of this invention. It is a transition figure of the control form which controls the mixture ratio of the mixing valve 16 with respect to the detected value detected by the flow counter 72 in 3rd Embodiment of this invention. It is a flowchart which shows the control processing of the temperature control of the control apparatus 200 in 3rd Embodiment of this invention.

Explanation of symbols

1 ... Hot water storage tank 2 ... Heat pump unit (heating means)
12 ... Introduction pipe (water supply route)
14 ... Outlet pipe (hot water supply route)
15 ... Water supply piping (bypass route)
16. Mixing valve (mixing means)
17 ... Piping (mixed hot water route)
23 ... Check valve 71 ... Hot water supply thermistor (hot water temperature detection means)
72 ... Flow rate counter (Tapping amount detection means)
200: Control device (control means)

Claims (6)

A hot water storage tank (1) for heating the internal water by the heating means (2) and storing it as hot water inside;
A water supply path (12) for sending water to the hot water storage tank (1);
A hot water supply path (14) for sending hot water stored in the hot water storage tank (1);
A bypass circuit (15) branched from the water supply path (12) and bypassing the hot water storage tank (1);
A mixed hot water path (17) in which the hot water supply path (14) and the bypass circuit (15) merge;
The amount of hot water detected is provided in the mixed hot water path (17), detects the flow rate of the mixed hot water passing through the mixed hot water path (17), and detects whether mixed hot water is supplied through the mixed hot water path (17). Means (72);
The mixing ratio of the hot water passing through the hot water supply path (14) and the water passing through the bypass circuit (15) is provided at the junction of the hot water supply path (14) and the bypass circuit (15). 14, 15) mixing means (16) controlled by adjusting the opening degree;
A hot water supply temperature detection means (71) provided on the downstream side of the mixing means (16) for detecting a hot water supply temperature for discharging the mixing means (16);
In a hot water supply apparatus comprising a control means (200) for controlling the mixing ratio of the mixing means (16) by PID control in which the hot water temperature detected by the hot water temperature detecting means (71) becomes a hot water supply set temperature.
When the flow rate detected by the tapping amount detection means (72) is small, the control means (200) is a mixture ratio at which the opening degree on the hot water supply path (14) side is fixed at a predetermined opening degree, or the PID A hot water supply apparatus, wherein the mixing means (16) is controlled to a mixing ratio of any one of mixing ratios by feedback control with a gain slower than control and a control time interval of a predetermined time. When the mixing means (16) is controlled by the PID control,
When the flow rate detected by the tapping amount detection means (72) changes to less than a predetermined value, the control means (200) detects that the predetermined time after detecting less than the predetermined value is less than the predetermined value The mixing means (16) is controlled so as to maintain the mixing ratio or the mixing ratio on the water side larger than the mixing ratio, and after the predetermined time has elapsed, the opening degree on the hot water supply path (14) side is a predetermined opening degree. The mixing means (16) is controlled to one of a mixing ratio fixed to a mixing ratio or a mixing ratio by feedback control with a gain slower than the PID control and a control time interval of a predetermined time. The hot water supply apparatus according to claim 1. When the mixing means (16) is controlled by the PID control,
When the flow rate detected by the tapping amount detecting means (72) detects that the flow rate detected by the tapping amount detecting means (72) is less than a predetermined value continuously for a predetermined time, the opening degree on the hot water supply path (14) side is a predetermined opening degree. The mixing means (16) is controlled to one of a mixing ratio fixed to a mixing ratio or a mixing ratio by feedback control with a gain slower than the PID control and a control time interval of a predetermined time. The hot water supply apparatus according to claim 1.   When the hot water temperature detected by the hot water supply temperature detecting means (71) is equal to or higher than a predetermined value, the control means (200) is configured so that the opening on the hot water supply path (14) side is closed. (16) is controlled, The hot-water supply apparatus as described in any one of Claim 1 thru | or 3 characterized by the above-mentioned.   The control means (200) detects a hot water supply stop for a predetermined time after detecting a hot water supply stop when the hot water detection means (72) detects a hot water supply stop through the mixed hot water path (17). The mixing means (16) is controlled so as to maintain the mixing ratio at that time or the mixing ratio on the water side larger than the mixing ratio, and after the predetermined time has elapsed, the opening degree on the hot water supply path (14) side is blocked. The hot water supply device according to any one of claims 1 to 4, wherein the mixing means (16) is controlled to a mixing ratio.   One or both of the hot water supply path (14) and the bypass circuit (15) are provided in the mixing means (16) via a check valve (23) for preventing backflow. The hot water supply device according to any one of claims 1 to 5.

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