JP7679265B2 - heat source machine - Google Patents

Description

The present invention relates to a heat source device that includes, inside a case, a heat exchanger, a heat source for heating the heat exchanger, a water supply passage and a hot water outlet passage connected to the upstream and downstream sides of the heat exchanger, respectively, a bypass passage that branches off from the water supply passage and is connected to the hot water outlet passage without passing through the heat exchanger, a first flow rate control valve that adjusts the total water flow rate of the heat exchanger and the bypass passage, and a second flow rate control valve connected to the first flow rate control valve that adjusts the ratio between the water flow rate of the heat exchanger and the bypass passage.

Conventionally, in this type of heat source device, the first flow control valve is placed on the inside bottom of the case and is connected to a water supply pipe located outside the case (see, for example, Patent Document 1).

If residual water is left in the valve chambers of both the first flow control valve and the second flow control valve, the residual water will freeze in cold weather, and the internal pressure of the valve housings of both valves will rise due to volume expansion caused by the freezing of the residual water, which may cause damage such as cracks to the valve housing. Therefore, in the technology described in Patent Document 1, a motor mounting plate for attaching an electric motor to the valve housings of both the electrically-operated first flow control valve and the second flow control valve is made of a plastically deformable material, and the valve guide is inserted axially into the valve housing while being pressed from the outside by this motor mounting plate. Then, the motor mounting plate is displaced axially outward due to volume expansion caused by the freezing of the residual water, and the valve guide is displaced axially outward, increasing the internal volume of the valve housing and absorbing the increase in internal pressure of the valve housing.

JP 2006-292131 A

However, in the technology described in Patent Document 1, valve guides are added as components of the first flow control valve and the second flow control valve in order to absorb the increase in internal pressure in the valve housing. This leads to a complex structure of the first flow control valve and the second flow control valve, which leads to complication of assembly work and parts inventory management, as well as higher costs.

In view of the above, the present invention aims to provide a heat source machine that can protect the valve housings of both the first and second flow control valves by absorbing the internal pressure rise caused by volume expansion associated with freezing of residual water in cold weather, without changing the structure of the first and second flow control valves, and can eliminate problems such as complication of assembly work and parts inventory management, as well as rising costs.

In order to solve the above problems, the present invention provides a heat source machine equipped inside a case with a heat exchanger, a heating source for heating the heat exchanger, a water supply passage and a hot water outlet passage connected to the upstream and downstream sides of the heat exchanger, respectively, a bypass passage branching off from the water supply passage and connected to the hot water outlet passage without passing through the heat exchanger, a first flow control valve for adjusting the total water flow rate of the heat exchanger and the bypass passage, and a second flow control valve connected to the first flow control valve for adjusting the ratio of the water flow rate of the heat exchanger to the bypass passage, wherein the first flow control valve is disposed on the inner bottom of the case and is connected to a water supply pipe located outside the case, and wherein a resin forming a valve housing of the second flow control valve contains an elastomer, and the breaking strain of the resin at temperatures below 0° C. is large enough to withstand an increase in internal pressure due to freezing of residual water and is larger than that of a resin not containing the elastomer forming the valve housing of the first flow control valve.

According to the heat source device of the present invention, even if the internal pressure of the valve housing of the first flow rate control valve rises due to volume expansion caused by freezing of residual water in cold weather, the heat source device can absorb the internal pressure rise and protect the valve housings of both the first flow rate control valve and the second flow rate control valve without changing the structure of the first flow rate control valve and the second flow rate control valve. Therefore, problems such as complicated assembly work for the first flow rate control valve and the inventory management of parts, and even rising costs can be eliminated.

FIG. 1 is a configuration diagram showing one embodiment of a heat source machine of the present invention. FIG. 2 is a configuration diagram of the dotted line portion shown in FIG. 1 as viewed from the X direction. 3 is a cross-sectional view of a main portion showing one embodiment of a first flow rate adjustment valve and a second flow rate adjustment valve of the heat source unit shown in FIGS. 1 and 2 . FIG.

1 and 2, the heat source device 1 according to one embodiment of the present invention includes a case 2 forming an outer shell. A can body 3 is stored inside the case 2. The can body 3 stores two burner units 4a and 4b arranged in parallel in the left-right direction of FIG. 1, which constitute a burner 4, and a heat exchanger 5 located above both burner units 4a and 4b and heated by each of the burner units 4a and 4b. In the heat source device 1, the burner 4 is used as a heat source for the heat exchanger 5. A combustion fan 6 that supplies combustion air to the burner 4 is connected to the lower surface 3a of the can body 3. An exhaust pipe 3b is provided at the upper end of the can body 3 located above the heat exchanger 5, and the exhaust pipe 3b penetrates the upper surface 2a of the case 2 and protrudes upward from the upper surface 2a of the case 2.

In addition, a gas supply passage 7 that supplies fuel gas to the burner 4 is housed inside the case 2. The gas supply passage 7 is connected to a gas supply pipe 9 located outside the case 2 via a first joint 8 provided on the inner bottom of the case 2. A first solenoid valve 10 and a proportional valve 11 are interposed in the gas supply passage 7, and the gas supply passage 7 branches into a first branch gas supply passage 7a and a second branch gas supply passage 7b downstream of the proportional valve 11. The first branch gas supply passage 7a penetrates upward through the lower surface 3a of the can body 3 and is connected to the burner unit 4a. Similarly, the second gas branch supply passage 7b also penetrates upward through the lower surface 3a of the can body 3 and is connected to the burner unit 4b. Second solenoid valves 12a and 12b for switching the capacity of the burner 4 are interposed in the first branch gas supply passage 7a and the second branch gas supply passage 7b, respectively.

The mixture of fuel gas supplied through the gas supply passage 7, the first branch gas supply passage 7a, and the second branch gas supply passage 7b and the combustion air supplied to the inside of the can body 3 by the operation of the combustion fan 6 is burned in one or both of the burner units 4a and 4b, and the heat of the combustion gas generated at this time is recovered in the heat exchanger 5. The heat exchanger 5 is composed of a first heat exchanger 5a that recovers the sensible heat of the combustion gas, and a second heat exchanger 5b located above the first heat exchanger 5a that recovers the latent heat of the combustion gas that has passed through the first heat exchanger 5a. The combustion gas whose heat has been recovered by both the first heat exchanger 5a and the second heat exchanger 5b is exhausted to the outside of the case 2 through the exhaust pipe 3b of the can body 3.

Furthermore, housed inside the case 2 are a water supply passage 13 connected to the upstream side of the heat exchanger 5 and supplying water to the second heat exchanger 5b, and a hot water outlet passage 14 connected to the downstream side of the heat exchanger 5 and outletting hot water from the first heat exchanger 5a. The water supply passage 13 is connected to a water supply pipe 16 located outside the case 2 via a second joint 15 provided at a position different from the first joint 8 on the inner bottom of the case 2. On the other hand, the downstream portion of the hot water outlet passage 14 is pulled downward from the bottom surface 2b of the case 2, or is connected to a hot water supply pipe or the like that communicates with the hot water supply destination via another joint.

The water supplied to the water supply passage 13 through the water supply pipe 16 is heated to hot water while flowing through the second heat exchanger 5b heated by the combustion gas generated by the combustion in the burner 4, and then flows through the first heat exchanger 5a, where it is further heated and discharged as hot water to the hot water outlet passage 14. A first flow rate control valve 17 and a second flow rate control valve 18 are interposed between the second joint 15 and the water supply passage 13. The first flow rate control valve 17 is located on the second joint 15 side, and the second flow rate control valve 18 is located on the water supply passage 13 side and is connected to the first flow rate control valve 17. Both the first flow rate control valve 17 and the second flow rate control valve 18 are motor-operated valves and are disposed on the inner bottom of the case 2. The second flow rate control valve 18 is connected to both the upstream end of the water supply passage 13 and the upstream end of the bypass passage 19, which is connected to the hot water outlet passage 14 without passing through the heat exchanger 5 and is located opposite to the downstream end that is the connection end to the hot water outlet passage 14.

The bypass passage 19 is a water flow path for allowing a portion of the water supplied through the water supply pipe 16 to flow into the hot water flowing through the hot water outlet passage 14, and for adjusting the temperature of the hot water supplied to the hot water supply destination to a predetermined temperature. The first flow rate control valve 17 is a valve for adjusting the total water flow rate of the heat exchanger 5, which is composed of the first heat exchanger 5a and the second heat exchanger 5b, and the bypass passage 19. The second flow rate control valve 18 is a valve for adjusting the ratio of the water flow rate of the heat exchanger 5 to the bypass passage 19.

Referring to FIG. 3, the first flow control valve 17 includes a valve housing 17d having a first port 17a to which the second joint 15 is connected, a second port 17b to which the second flow control valve 18 is connected, a valve chamber 17c communicating with the first port 17a and the second port 17b, a valve shaft 17f that is moved forward and backward by a motor 17e such as a stepping motor via a feed screw mechanism (not shown), and a valve body 17g that is connected to the valve shaft 17f and changes the degree of communication opening of the first port 17a to the valve chamber 17c.

A water flow sensor 20 having an impeller 20a that rotates with the water flow is provided inside a passage extending upward toward the valve chamber 17c of the first port 17a. The valve chamber 17c of the first flow control valve 17 is provided with a communication port 17h that opens in the axial direction of the valve shaft 17f at a portion located on the second port 17b side, and a valve seat 17i on the outer periphery of the communication port 17h. A flange 17g1 that protrudes radially outward is provided in a portion of the valve body _17g , and the outer diameter of the flange _17g1 is larger than the diameter of the communication hole 17h and is seated on the valve seat 17i. The outer diameter of the portion of the valve body 17g excluding the flange _17g1 , i.e., the portion of the valve body 17g located closer to the communication port _17h than the flange 17g1, is smaller than the diameter of the communication port 17h. Therefore, when the valve shaft 17f advances, the valve body 17g except for the flange _17g1 advances into the first port 17a through the communication port 17h. A spring 17j is fitted onto the valve shaft 17f so that the biasing force of the spring 17j acts on the valve body 17g.

When the valve shaft 17f is advanced to the left stroke end position and the flange _17g1 of the valve body 17g is seated on the valve seat 17i, the communication port 17h is closed and the water from the water supply pipe 16 shown in Figures 1 and 2 that flows into the valve chamber 17c through the first port 17a does not flow to the second port 17b. At this time, the total amount of water passing through the heat exchanger 5 and the bypass passage 19 becomes zero. On the other hand, as the valve shaft 17f is retreated to the right and the flange _17g1 of the valve body 17g leaves the valve seat 17i and the part of the valve body _17g other than the flange 17g1 passes through the communication port 17h, the amount of water passing through the second port 17b gradually increases , and when the valve shaft 17f is retreated to the right stroke end position, the total amount of water passing through the heat exchanger 5 and the bypass passage 19 becomes maximum. In this way, the first flow control valve 17 adjusts the opening degree of the communication port 17h by moving the valve shaft 17f back and forth between the left stroke end position and the right stroke end position, and adjusts the total water flow rate of the heat exchanger 5 shown in Figure 1 and the bypass path 19.

The second flow control valve 18 includes a first port 18a that is fitted into the second port 17b of the first flow control valve 17 to connect the second flow control valve 18 to the first flow control valve 17, a second port 18b that is connected to the upstream end of the water supply passage 13 shown in Figures 1 and 2, a third port 18c that is connected to the upstream end of the bypass passage 19, a valve housing 18e that has a valve chamber 18d that communicates with the first port 18a, the second port 18b, and the third port 18c, a valve shaft 18g that is moved vertically by a motor 18f such as a stepping motor via a feed screw mechanism not shown, and umbrella-shaped first and second valve bodies 18h and 18i that are connected to the valve shaft 18g and that respectively change the degree of communication opening between the second port 18b and the third port 18c relative to the valve chamber 18d. The first valve body 18h expands in diameter toward the top, while the second valve body expands in diameter toward the bottom.

In the second flow rate control valve 18, a first valve seat 18j and a second valve seat 18k are provided in the valve chamber 18d at the portions extending from the first port 18a toward the second port 18b and the third port 18c, respectively. A first valve hole 18j1 and a second valve hole 18k1 are formed in the first valve seat 18j _and the second valve seat 18k, respectively, in the axial direction of the valve shaft _18g . In other words, the degree of communication between the second port 18b and the third port 18c with respect to the valve chamber 18d varies depending on the degree of opening of the first valve hole 18j1 by the first valve body 18h and the degree of opening of the second valve hole _18k1 by the second valve body _18i when the valve shaft 18g moves in the vertical direction. For example, when the valve shaft 18g is moved to the lower stroke end position in Fig. 4, the first valve body 18h seats on the first valve seat 18j from above and the second valve hole _18k1 is fully opened, and when the valve shaft 18g is moved to the upper stroke end position in Fig. 4, the second valve body 18i seats on the second valve seat 18k from below and the first valve hole _18j1 is fully opened. In this way, the second flow rate control valve 18 adjusts the opening degree of the first valve hole _18j1 and the second valve hole _18k1 by vertical movement of the valve shaft 18h between the lower stroke end position and the upper stroke end position, and adjusts the ratio between the water flow rate of the heat exchanger 5 shown in Fig. 1 and the water flow rate of the bypass passage 19.

As described above, the first flow control valve 17 and the second flow control valve 18 are disposed on the inner bottom of the case 2. If the valves 17, 18 are not drained and residual water is left in the valve chambers 17c, 18d, etc., the residual water will freeze in cold weather. This freezing of residual water is particularly likely to occur in the first flow control valve 17 disposed near the second joint 15 provided on the underside 2b of the case 2 shown in Figures 1 and 2. When the residual water in the valve chamber 17e of the first flow control valve 17 freezes first, the internal pressure of the valve housing 17d of the first flow control valve 17 rises due to the volume expansion from water to ice, and this internal pressure rise is transmitted to the valve housing 18e of the second flow control valve 18, where the residual water is not frozen. Such an internal pressure rise has an adverse effect on the valve housing 18e of the second flow control valve 18, and there is a risk of damage such as cracks occurring in the valve housing 18e.

Therefore, in the heat source unit 1, the fracture toughness of the resin forming the valve housing 18e of the second flow rate control valve 18 is made larger than that of the resin forming the valve housing 17d of the first flow rate control valve 17, thereby improving the low-temperature toughness. Specifically, the fracture strain of the resin forming the valve housing 18e of the second flow rate control valve 18 at temperatures below 0°C, which is the freezing point of water, is large enough to withstand the increase in internal pressure caused by the freezing of residual water, and is larger than that of the resin forming the valve housing 17d of the first flow rate control valve 17. Therefore, even if the internal pressure of the valve housing 17d of the first flow rate control valve 17 increases due to volume expansion caused by the freezing of residual water, the valve housing 18e of the second flow rate control valve 18 can absorb the increase in internal pressure of the valve housing 17d of the first flow rate control valve 17. Therefore, since the valve housing 17d of the first flow rate control valve 17 does not necessarily require high low-temperature toughness, it is possible to use the resin not containing elastomer that has been used so far without changing it. The resin that can be used to form the valve housing 18e of the second flow rate control valve 18 is, for example, a mixed resin in which an elastomer is blended with polyphenylene sulfide (PPS).

In this way, in the heat source unit 1, by changing only the resin forming the valve housing 18e of the second flow control valve 18 without changing the structure of the first flow control valve 17 and the second flow control valve 18, it is possible to absorb the increase in internal pressure of the valve housing 17d of the first flow control valve 17 caused by volume expansion accompanying the freezing of residual water in cold weather, and protect the valve housings 17d, 18e of both the first flow control valve 17 and the second flow control valve 18. Therefore, problems such as complication of assembly work and parts inventory management for the first flow control valve 17 and the second flow control valve 18, as well as rising costs, can be eliminated.

If the valve chamber 18d of the second flow control valve 18 is not drained and the remaining water is left in the valve chamber 18d, there is a possibility that the remaining water will freeze. However, the valve housing 18e of the second flow control valve 18 is made of a resin whose breaking strain at temperatures below 0°C is large enough to withstand the increase in internal pressure caused by the freezing of the remaining water , and therefore can withstand the increase in internal pressure caused by the volume expansion that accompanies the freezing of the remaining water. Therefore, the occurrence of damage such as cracks in the valve housing 18e is sufficiently suppressed.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. For example, there are no particular limitations on the structures of the burner 4, heat exchanger 5, and combustion fan 6, as well as the structures of the gas supply path 7, water supply path 13, hot water outlet path 14, and bypass path 19. The same is true for the structures of the first flow rate control valve 17 and the second flow rate control valve 18.

1...heat source unit, 2...case, 4...heat source (burner), 5...heat exchanger, 13...water supply passage, 14...water outlet passage, 16...water supply pipe, 17...first flow control valve, 17d...valve housing, 18...second flow control valve, 18e...valve housing, 19...bypass passage.

Claims (1)

A heat source machine including, inside a case, a heat exchanger, a heat source for heating the heat exchanger, a water supply passage and a hot water outlet passage connected to the upstream and downstream sides of the heat exchanger, respectively, a bypass passage branching off from the water supply passage and connected to the hot water outlet passage without passing through the heat exchanger, a first flow rate control valve for adjusting the total water flow rate of the heat exchanger and the bypass passage, and a second flow rate control valve connected to the first flow rate control valve for adjusting the ratio of the water flow rate of the heat exchanger and the bypass passage,
The first flow rate control valve is disposed on the inner bottom of the case and connected to a water supply pipe located outside the case,
A heat source machine characterized in that the resin forming the valve housing of the second flow control valve is a mixed resin containing an elastomer, and the breaking strain of the resin at temperatures below 0°C is large enough to withstand the increase in internal pressure caused by the freezing of residual water, and is larger than that of a resin not containing elastomer that forms the valve housing of the first flow control valve.

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