JP5810112B2 - Water heater - Google Patents

Description

  The present invention relates to a water heater provided with a bypass path that connects an upstream water supply path and a downstream hot water supply path of a heat exchanger heated by a burner in parallel with the heat exchanger.

  In the water heater, when the temperature of the hot water discharged from the heat exchanger is low, water vapor in the combustion exhaust of the burner is condensed in the heat exchanger and drainage is generated. If a bypass passage is provided, even if the hot water temperature from the heat exchanger is higher than the hot water supply set temperature, the water from the bypass passage is mixed with the hot water discharged from the heat exchanger, and downstream of the bypass passage junction. Hot water at the hot water supply set temperature can be supplied to the hot water supply passage. Therefore, the generation of drain can be prevented even when the hot water supply set temperature is low.

  Here, in the water heater, generally, the total water flow amount to the heat exchanger and the bypass passage is varied in the upstream portion from the bypass passage branch portion of the water supply passage or the downstream portion from the bypass passage merging portion of the hot water passage. An electric water amount control valve is provided, and if the hot water supply temperature does not reach the set temperature even when the burner combustion amount is maximized, control is performed to reduce the total water flow rate.

  In addition, conventionally, in addition to the water amount adjustment valve, there is also known one provided with a bypass valve that adjusts the ratio of the amount of water flow to the heat exchanger and the amount of water flow to the bypass passage (see, for example, Patent Document 1). . However, since the cost increases when the bypass valve is provided, a fixed bypass water heater without a bypass valve is also widely used (see, for example, Patent Document 2).

  By the way, in the fixed bypass system, the bypass ratio (the amount of water passing through the bypass passage / the amount of water passing through the heat exchanger) should theoretically be a predetermined value corresponding to the pipe diameter of the bypass passage. If the water supply pressure is so low that a sufficient amount of water cannot be obtained even in a sufficiently opened state, the substantial bypass ratio becomes smaller than a predetermined value. Therefore, when the feed water pressure is so low, the difference between the hot water temperature from the heat exchanger and the hot water set temperature becomes relatively small, and when the hot water set temperature becomes low, drainage tends to occur.

JP 2003-194404 A JP-A-11-294761

  In view of the above, the present invention provides a water heater that can prevent a substantial decrease in the bypass ratio when the feed water pressure is low without using a bypass valve separate from the water amount adjustment valve. It is an issue.

In order to solve the above-mentioned problem, to the bypass path connecting the upstream water supply path and the downstream hot water supply path of the heat exchanger heated by the burner in parallel with the heat exchanger, to the heat exchanger and the bypass path In the water heater provided with an electrically operated water amount control valve that varies the total water flow rate, the valve housing of the water amount control valve is upstream of the bypass channel branching portion of the water supply channel or downstream of the bypass channel junction of the hot water channel A first port connected to the portion, a second port connected to a portion downstream of the bypass passage branching portion of the water supply passage or an upstream portion of the bypass passage merging portion of the hot water supply passage, and a third connected to the bypass passage. A first valve chamber that communicates with the port, a first valve chamber that communicates with the first port, and a second valve chamber that communicates with the second port and the third port and constitutes the bypass channel branching portion of the water supply channel or the bypass channel merging unit of the hot water channel The water volume control valve has a valve shaft driven by a motor A main valve body that is connected to the valve shaft and varies the communication opening degree of the second valve chamber with respect to the first valve chamber, and a sub-valve element that is connected to the valve shaft and changes the communication opening degree of the third port to the second valve chamber. The sub-valve body maintains a constant opening degree of the third port with respect to the second valve chamber when the main valve body is closer to the closed side than the predetermined intermediate opening position, and the main valve body is opened intermediately. The opening degree of the third port with respect to the second valve chamber is increased when moving to the opening side relative to the position , and the main valve body opens intermediately when the feed water pressure is lower than a predetermined reference pressure. The valve shaft is driven so as to move to the opening side from the position .

  Here, if the communication opening degree of the 3rd port with respect to a 2nd valve chamber is made to increase, the water flow amount to a bypass channel will increase. Then, according to the present invention, when the water supply pressure is low, the valve body is driven so that the main valve body of the water amount adjusting valve moves to the opening side from the intermediate opening position. Can be compensated for to some extent, and the opening degree of the third port with respect to the second valve chamber can be increased by the sub-valve to prevent a substantial decrease in the bypass ratio. Furthermore, since only the auxiliary valve body is added to the water amount adjusting valve, the cost can be reduced as compared with a case where a bypass valve separate from the water amount adjusting valve is provided.

  Moreover, in this invention, it is provided with the detection means which detects the total water flow amount to a heat exchanger and a bypass, and with respect to the 1st valve chamber obtained from the position of the main valve body calculated based on the rotation information of a motor Based on the correlation between the communication opening degree of the second valve chamber and the detected water amount of the detection means, it is determined whether the feed water pressure is higher or lower than a predetermined reference pressure. It is desirable to drive the valve shaft so that the body moves to the opening side from the intermediate opening position. According to this, when the feed water pressure is low, the communication opening degree of the third port with respect to the second valve chamber can be automatically increased, and a special sensor for detecting the feed water pressure becomes unnecessary, which is advantageous. .

Sectional drawing of the water quantity adjustment valve which attached the piping circuit of the hot water heater of 1st Embodiment of this invention. The perspective view of the subvalve body of the water quantity adjustment valve of FIG. Sectional drawing of the water quantity adjustment valve which attached the piping circuit of the hot water heater of 2nd Embodiment of this invention.

  The water heater of the embodiment of the present invention shown in FIG. 1 includes a burner 1 and a heat exchanger 2 heated by the burner 1. Furthermore, the total water flow to the heat exchanger 2 and the bypass path 5, the bypass path 5 connecting the upstream water supply path 3 and the downstream hot water supply path 4 of the heat exchanger 2 in parallel with the heat exchanger 2. And an electrically-operated water amount adjusting valve 6 that can vary the above.

  The valve housing 61 of the water amount adjusting valve 6 is connected to the first port 611 connected to the upstream portion 3a of the bypass passage 5 branching portion of the water supply passage 3, and to the downstream portion 3b of the bypass passage 5 branching portion of the water supply passage 3 The second port 612, the third port 613 connected to the bypass passage 5, the first valve chamber 61a communicating with the first port 611, the second port 612 and the third port 613, and the water supply passage 3 and a second valve chamber 61b constituting a bypass passage 5 branching portion.

  Note that the end surface of the first valve chamber 61a on the second valve chamber 61b side is a valve seat 61c in which an opening communicating with the second valve chamber 61b is formed. Further, the second valve chamber 61 b is formed in a columnar shape concentric with the second port 612. A valve hole 61d communicating with the third port 613 is formed in a part of the peripheral surface of the second valve chamber 61b.

  The water amount adjusting valve 6 includes a valve shaft 63 that is driven by a motor 62 such as a stepping motor, and a main valve body 64 that is connected to the valve shaft 63 and varies the opening degree of the second valve chamber 61b with respect to the first valve chamber 61a. And a sub-valve element 65 that is connected to the valve shaft 63 and varies the degree of communication of the third port 613 with respect to the second valve chamber 61b.

  The valve shaft 63 is slidably inserted into a guide member 614 that is fixed to the valve housing 61 that is fitted to the outer end portion of the first valve chamber 61a. A spline 63 a is formed on the outer periphery of the axially outer end portion of the valve shaft 63. A spline sleeve 62 a that is rotationally driven by the motor 62 is fitted on the spline 63 a, and the valve shaft 63 is rotated forward and backward by the motor 62. To be. Further, a male screw 63b adjacent to the spline 63a is formed on the valve shaft 63, and this male screw 63b is screwed to a female screw 614a formed on the inner periphery of the outer end portion of the guide member 614. It is made to advance and retreat in the axial direction by the opening / closing stroke.

  The sub-valve element 65 is connected to the inner end of the valve shaft 63 in the axial direction while being prevented from coming off by a retaining ring 63c. Further, the main valve element 64 is connected to the valve axis 63 by a spring 64a on the sub-valve element 65 side. Extrapolated in the state of being energized. The main valve body 64 advances and retreats toward the valve seat 61c as the valve shaft 63 advances and retreats in the first valve chamber 61a. When the main valve body 64 moves to the closing side approaching the valve seat 61c, the communication opening degree of the second valve chamber 61b with respect to the first valve chamber 61a is gradually reduced. As 64 moves to the open side away from the valve seat 61c, the opening degree of the second valve chamber 61b with respect to the first valve chamber 61a gradually increases.

  The sub-valve element 65 rotates and advances and retreats integrally with the valve shaft 63 and is formed in a cylindrical shape that is fitted in the second valve chamber 61 b, and its internal space is always in communication with the second port 612. . In the peripheral wall portion of the sub-valve element 65, a slit 651 is formed continuously in the circumferential direction to communicate the internal space with the valve hole 61d. A plurality of ribs 652 extending in the bus-line direction are formed on the inner peripheral surface of the peripheral wall portion of the sub-valve element 65 so as to prevent the sub-valve element 65 from being separated by the slit 651. In addition, a plurality of through holes 653 into which water from the first valve chamber 61a flows is formed in the end wall portion of the sub valve body 65 on the main valve body 64 side.

  Here, as shown in FIG. 2, a part of the slit 651 in the circumferential direction is formed in a wide part 651a having a width wider than that of the other part. When the main valve body 64 is on the closing side with respect to the predetermined intermediate opening position, that is, when the rotation angle of the valve shaft 63 is in an angle range for moving the main valve body 64 to the closing side with respect to the intermediate opening position. The portions other than the wide portion 651a of the slit 651 are directed toward the valve hole 61d so that the communication opening degree of the third port 613 with respect to the second valve chamber 61b is maintained at a relatively small constant opening degree. Further, when the main valve body 64 moves to the opening side from the intermediate opening position, that is, when the valve shaft 63 is rotated in the direction in which the main valve body 64 moves to the opening side from the angle range, the slit 651 is widened. The part 651a faces the valve hole 61d side so that the communication opening degree of the third port 613 with respect to the second valve chamber 61b increases.

  A water amount sensor 7 having an impeller 7a that is rotated by a water flow is provided in a passage portion between the first port 611 of the valve housing 61 and the first valve chamber 61a, and the heat exchanger 2 And a detecting means for detecting the total water flow amount to the bypass 5 is configured. Further, a temperature sensor 8 that detects the water temperature (water supply temperature) of the water supply path 3 and a temperature sensor 9 that detects the hot water temperature (hot water supply temperature) of the downstream portion 4 a from the junction of the bypass path 5 of the hot water supply path 4 are provided. . Then, a controller (not shown) calculates the amount of heat necessary for setting the hot water supply temperature to the set temperature from the deviation between the hot water supply set temperature and the water supply temperature and the amount of water detected by the water amount sensor 7 so that this amount of heat can be obtained. The combustion amount of the burner 1 is feedforward controlled, and the combustion amount of the burner 1 is feedback controlled so that the hot water supply temperature becomes the set temperature. If the hot water supply temperature does not rise to the set temperature even when the burner 1 has the maximum combustion amount, the total water flow amount to the heat exchanger 2 and the bypass passage 5 is decreased by the water amount adjustment valve 6 to thereby increase the hot water supply temperature. Increase to set temperature.

  By the way, when the water supply pressure is low enough that a sufficient amount of water cannot be obtained even when the water amount adjustment valve 6 is sufficiently opened, that is, when the water supply pressure is lower than a predetermined reference pressure, Substantial bypass ratio (amount of water flowing to bypass channel 5 / amount of water flowing to heat exchanger 2) decreases, and the temperature of hot water from heat exchanger 2 (upstream portion of merging portion of bypass channel 5 of hot water channel 4) The difference between the hot water temperature 4b) and the hot water supply temperature becomes relatively small, and drainage tends to occur when the hot water supply set temperature is lowered.

  Here, from the position of the main valve body 64 calculated based on the amount of water detected by the water amount sensor 7 (total amount of water passing through the heat exchanger 2 and the bypass 5) and the rotation information of the motor 62 of the water amount adjusting valve 6. The water supply pressure can be calculated from the correlation between the obtained opening degree of the second valve chamber 61b and the first valve chamber 61a. Therefore, in the present embodiment, the controller determines whether or not the water supply pressure is higher than the predetermined reference pressure based on the correlation, and when it is determined that the supply water pressure is low, the main valve of the water amount adjusting valve 6 is determined. Control was performed to drive the valve shaft 63 so that the body 64 moves to the opening side from the intermediate opening position.

  When the communication opening degree of the third port 613 with respect to the second valve chamber 61b is increased, the amount of water flowing into the bypass passage 5 is increased. And according to this embodiment, when the water supply pressure is lower than the reference pressure, the main valve body 64 of the water amount adjusting valve 6 is moved to the opening side from the intermediate opening position, so that the total water flow rate is reduced due to a decrease in the water supply pressure. Can be compensated for to some extent, and the opening degree of the third port 613 with respect to the second valve chamber 61b can be increased by the sub-valve element 65 to prevent the substantial bypass ratio from being lowered. Thereby, when the feed water pressure is lower than the reference pressure, it is difficult for drainage to occur even if the hot water supply set temperature is lowered. Further, since only the auxiliary valve element 65 is added to the water amount adjusting valve 6, the cost can be reduced as compared with the case where a bypass valve separate from the water amount adjusting valve 6 is provided.

  Further, in the present embodiment, based on the correlation between the communication opening degree of the second valve chamber 61b with respect to the first valve chamber 61a obtained from the rotation information of the motor 62 of the water amount adjustment valve 6 and the detected water amount of the water amount sensor 7. Since it is determined whether the feed water pressure is higher or lower than a predetermined reference pressure, a special sensor for detecting the feed water pressure becomes unnecessary, which is advantageous in reducing costs.

  Next, a second embodiment shown in FIG. 3 will be described. In the second embodiment, the downstream portion 4a is connected to the first port 611 of the valve housing 61 of the water amount adjusting valve 6 from the junction of the bypass passage 5 of the hot water supply passage 4, and the bypass passage of the hot water supply passage 4 to the second port 612. The upstream portion 4b is connected to the 5 junction portion, and further, the bypass passage 5 is connected to the third port 613, and the bypass passage 5 junction portion of the hot water supply passage 4 is configured by the second valve chamber 61b. Also in this case, the same effect as the first embodiment can be obtained.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to this. For example, in the above embodiment, the opening degree of the third port 613 with respect to the second valve chamber 61b is varied by the rotation of the sub-valve element 65, but the valve shaft 63 does not rotate but moves forward and backward in the axial direction. Thus, a slit extending in the axial direction may be formed on the surface of the sub-valve element 65 facing the valve hole 61d side. In this case, when the main valve body 64 moves to the opening side from the intermediate opening position, the wide portion of the slit is displaced to the axial position facing the valve hole 61d, and the third port 613 with respect to the second valve chamber 61b is displaced. The communication opening is configured to increase.

  DESCRIPTION OF SYMBOLS 1 ... Burner, 2 ... Heat exchanger, 3 ... Water supply path, 3a ... Upstream part from bypass path branch part of water supply path, 3b ... Downstream part from bypass path branch part of water supply path, 4 ... Hot water supply path, 4a ... The downstream portion of the hot water supply passage bypass portion, 4b... The upstream portion of the hot water supply passage bypass portion, 5. 2nd valve chamber, 611 ... 1st port, 612 ... 2nd port, 613 ... 3rd port, 62 ... Motor, 63 ... Valve shaft, 64 ... Main valve body, 65 ... Sub valve body.

Claims (2)

Electricity that varies the total water flow to the heat exchanger and bypass path, bypass path that connects the upstream water supply path and downstream hot water supply path of the heat exchanger heated by the burner in parallel with the heat exchanger In a water heater provided with a water amount control valve of the type
The valve housing of the water amount adjusting valve has a first port connected to a portion upstream of the bypass passage branch portion of the water supply passage or a downstream portion of the bypass passage junction portion of the hot water supply passage, and downstream of the bypass passage branch portion of the water supply passage. A second port connected to a portion or a portion upstream of the bypass passage merging portion of the hot water supply passage, a third port connected to the bypass passage, a first valve chamber communicating with the first port, a second port, and a second port; A second valve chamber that communicates with 3 ports and constitutes a bypass passage branching portion of a water supply passage or a bypass passage merging portion of a hot water supply passage;
The water amount adjusting valve includes a valve shaft that is driven by a motor, a main valve body that is connected to the valve shaft and varies a communication opening degree of the second valve chamber with respect to the first valve chamber, and is connected to the valve shaft and that is connected to the second valve chamber. A sub-valve that varies the communication opening of the third port,
When the main valve body is on the closed side with respect to the predetermined intermediate opening position, the auxiliary valve body maintains the communication opening of the third port with respect to the second valve chamber to be constant, and the main valve body opens more than the intermediate opening position. Configured to increase the communication opening degree of the third port with respect to the second valve chamber when moving to the side ,
A water heater , wherein a valve shaft is driven so that a main valve element moves to an opening side from an intermediate opening position when a supply water pressure is lower than a predetermined reference pressure .   Detection means for detecting a total water flow amount to the heat exchanger and the bypass passage, and the first valve chamber obtained from the position of the main valve body calculated based on rotation information of the motor. Based on the correlation between the communication opening degree of the two valve chambers and the detected water amount of the detection means, it is determined whether the feed water pressure is higher or lower than the predetermined reference pressure, and when it is determined that the supply water pressure is lower, The water heater according to claim 1, wherein the valve shaft is driven so that the valve shaft moves to an opening side from an intermediate opening position.

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