Gas flow rate-adjusting apparatus and heating cooker mounted with gas flow rate-adjusting apparatus

Abstract

To stabilize a flow rate of fuel gas at a specific flow rate regardless of deviation in a stop position of a needle valve body within a valve chamber of a gas flow rate-adjusting apparatus.SOLUTION: A needle valve body is accommodated in a valve chamber, and a flow rate of fuel gas is adjusted by moving the needle valve body in an advancing and retracting direction along a center line of the valve chamber. The valve chamber has a step part 20c between a small-diameter part 20a and a large-diameter part 20b having different inner diameters, and a gas passage communicates between an end surface of the small-diameter part and a circumferential surface of the large-diameter part. The needle valve body has, at one end, a valve head part 22 insertable into the small-diameter part, and at the other end, a connection part connected to a drive mechanism. Further, while an inner diameter of the small-diameter part of the valve chamber is substantially constant, the valve head part of the needle valve body is provided, in order from a tip side toward the connection part side, with: a tip straight part 22a having a substantially constant outer diameter; a reduced-diameter part 22b having a decreasing outer diameter; and an enlarged-diameter part 22c having an increasing outer diameter. An angle formed between the reduced-diameter part and the enlarged-diameter part is an obtuse angle.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a gas flow rate regulator that is provided in a gas passage that supplies fuel gas to a combustion device and regulates the flow rate of the fuel gas, and to a cooking appliance equipped with the gas flow rate regulator. [Background technology]

[0002] Combustion devices such as gas burners that burn a mixture of fuel gas and air are widely used as heat sources for cooking appliances such as gas stoves. In addition, a gas flow regulator that regulates the flow rate of the fuel gas is generally provided in a gas passage that supplies the fuel gas to the combustion device, and the heating power of the combustion device can be changed by increasing or decreasing the flow rate of the fuel gas supplied to the combustion device with the gas flow regulator.

[0003] One known gas flow rate control device has a structure in which a substantially cylindrical needle valve element is housed in a substantially cylindrical valve chamber, and the needle valve element can move back and forth along the centerline of the valve chamber (see, for example, Patent Document 1). The valve chamber has a step between a small diameter section and a large diameter section, which have different inner diameters. A gas passage connects the end face of the small diameter section opposite the step to the circumferential surface of the large diameter section. The needle valve element has a valve head at one end adjacent to the small diameter section that can be inserted into the small diameter section, and a connection part at the other end opposite the valve head to a drive mechanism that drives the needle valve element. The inner diameter of the small diameter section and the outer diameter of the valve head are both substantially constant. Even if the valve head is inserted into the small diameter section and the insertion amount increases or decreases, the gap between the small diameter section and the valve head (the cross-sectional area of ​​the fuel gas passage) does not change significantly. However, the passage resistance of the fuel gas increases as the insertion amount increases. Therefore, the flow rate of the fuel gas can be adjusted by adjusting the insertion amount of the valve head into the small diameter section, which is linked to the movement of the needle valve element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-278811 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a gas flow control device that adjusts the flow rate of fuel gas by moving a needle valve element in a valve chamber in a forward / backward direction as described above, the stopping position of the needle valve element due to the drive mechanism may deviate from the target position, and if this changes the insertion amount of the valve head into the narrow diameter portion, the flow rate of fuel gas may fluctuate, resulting in unstable heating power of the combustion device. For example, at a specific flow rate of fuel gas corresponding to ignition, if the stopping position of the needle valve element deviates and the flow rate of fuel gas is insufficient, this can result in poor ignition, or if the flow rate of fuel gas is excessive, flames may overflow from the bottom of the cooking vessel.

[0006] The present invention has been made in response to the above-mentioned problems in the conventional technology, and aims to provide a technology that can stabilize the flow rate of fuel gas at a specific flow rate regardless of deviation of the stopping position of the needle valve element within the valve chamber of a gas flow control device. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the gas flow rate regulator of the present invention employs the following configuration: <First aspect> A gas flow rate control device is provided in a gas passage that supplies fuel gas to a combustion device, the gas flow rate control device comprising: a substantially cylindrical needle valve element housed in a substantially cylindrical valve chamber; and the gas flow rate control device controls a flow rate of the fuel gas supplied to the combustion device by moving the needle valve element in a forward and backward direction along a center line of the valve chamber, the valve chamber has a step between a small diameter portion and a large diameter portion having different inner diameters, and the gas passage communicates with an end face of the small diameter portion opposite to the step and a peripheral surface of the large diameter portion, the needle valve body has a valve head portion at one end adjacent to the narrow diameter portion, the valve head portion being insertable into the narrow diameter portion, and a connection portion at the other end opposite to the valve head portion, the connection portion being connected to a drive mechanism that drives the needle valve body; The inner diameter of the narrow diameter portion is substantially constant, The valve head a tip straight portion provided at the tip and having a substantially constant outer diameter; a tapered portion provided closer to the connection portion than the tip straight portion and having an outer diameter that decreases toward the connection portion; an expanded diameter portion that is provided closer to the connection portion than the reduced diameter portion and has an outer diameter that increases toward the connection portion; Equipped with The angle formed between the reduced diameter portion and the expanded diameter portion is an obtuse angle. It is characterized by:

[0008] In the gas flow rate control device of the first aspect, as the valve head section is inserted into the narrowed diameter section, first, in the tip straight section, as the insertion amount into the narrowed diameter section increases, the resistance to fuel gas passage increases even though the gap (cross-sectional area of ​​the fuel gas passage) between the narrowed diameter section and the tip straight section remains unchanged, resulting in a decrease in the flow rate of the fuel gas. Next, in the contracted diameter section, even if the insertion amount into the narrowed diameter section increases, the increase in the resistance to fuel gas passage is suppressed by the expansion of the gap between the narrowed diameter section and the contracted diameter section, thereby suppressing a decrease in the flow rate of the fuel gas and maintaining a substantially constant flow rate. As a result, even if the stopping position of the needle valve body deviates from the target position, the flow rate of the fuel gas can be stabilized within the range in which the insertion amount of the contracted diameter section relative to the narrowed diameter section changes due to the deviation of the stopping position. In particular, by stabilizing the flow rate of fuel gas at a specific flow rate, such as during ignition, it is possible to stabilize the thermal power of the combustion device.

[0009] Furthermore, by forming an obtuse angle between the reduced diameter portion and the expanded diameter portion, the resistance to fuel gas passage gradually increases when the valve head portion is inserted into the narrow diameter portion, transitioning from the reduced diameter portion to the expanded diameter portion, compared to when the angle is an acute angle, and a sudden decrease in the flow rate of fuel gas is less likely to occur, thereby suppressing a sudden change in the heating power of the combustion device. Furthermore, when the user manually operates the drive mechanism, an obtuse angle between the reduced diameter portion and the expanded diameter portion can suppress an increase in operating load (uncomfortable operation) caused by the expanded diameter portion coming into contact with a step in the valve chest as the valve head portion is inserted into the narrow diameter portion, compared to when the angle is an acute angle.

[0010] <Second aspect> In the gas flow rate regulator of the first aspect, The length of the reduced diameter portion in the advancing / retracting direction of the valve head is longer than the length of the expanded diameter portion. It is characterized by:

[0011] In the gas flow rate control device of the second aspect, by setting the reduced diameter portion to be long, even if the stop position of the needle valve element deviates from the target position, the reduced diameter portion can suppress fluctuations in the passage resistance of the fuel gas that accompany the deviation of the stop position, thereby ensuring a wide range in which the flow rate of the fuel gas can be kept approximately constant.

[0012] <Third aspect> In the gas flow rate regulator of the first or second aspect, The valve head portion is provided with a plurality of combinations of the reduced diameter portion and the expanded diameter portion in the advancing / retracting direction, The combinations are different, and the angle formed between the adjacent enlarged diameter portion and the adjacent reduced diameter portion is an obtuse angle. It is characterized by:

[0013] In the gas flow rate control device of the third aspect, by providing the valve head with multiple sets of reduced diameter portions and expanded diameter portions, it is possible to stabilize the heating power of the combustion device at multiple stages, thereby improving the convenience of adjusting the heating power of the combustion device. Furthermore, because the angles formed between adjacent expanded diameter portions and reduced diameter portions of different sets are obtuse, the change in the resistance to the passage of fuel gas when the insertion of the valve head into the small diameter portion transitions from the expanded diameter portion to the next reduced diameter portion is more gradual than in the case where the angles are acute, and abrupt changes in the flow rate of fuel gas are less likely to occur, thereby suppressing abrupt changes in heating power.

[0014] <Fourth aspect> In the gas flow rate regulator of the first or second aspect, a proximal straight portion having a substantially constant outer diameter is provided on the valve head portion closer to the connecting portion than the enlarged diameter portion, The outer diameter of the tip straight portion is smaller than the outer diameter of the base straight portion. It is characterized by:

[0015] In the gas flow rate regulator of the fourth aspect, by setting the outer diameter of the tip straight portion to be small, when the user manually drives the needle valve element and the tip straight portion begins to enter the narrow diameter portion, the tip straight portion is less likely to come into contact with a step in the valve chamber, thereby suppressing an increase in the operating load (uncomfortable operation). Also, by setting the outer diameter of the base straight portion to be large, when the valve head portion is inserted into the narrow diameter portion up to the base straight portion, variation in the position of the valve head portion in the radial direction of the narrow diameter portion can be suppressed, thereby making it possible to stabilize the heating power on the low side of the combustion device.

[0016] <Fifth aspect> The gas flow rate regulator according to any one of the first to fourth aspects is mounted on a cooking appliance, and food to be cooked is heated by combustion in the combustion device.

[0017] In such a cooking appliance, the flow rate of the fuel gas can be stabilized at a specific flow rate at the time of ignition, regardless of the deviation of the stopping position of the needle valve body in the valve chamber of the gas flow control device installed, thereby stabilizing the heat output of the combustion device. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view showing the appearance of a gas stove 1 as an example of a cooking device according to the present embodiment. [Figure 2] 2 is an explanatory diagram showing a schematic diagram of a fuel gas supply path in the gas stove 1. FIG. [Figure 3] FIG. 2 is an explanatory diagram showing the structure of a flow rate adjustment valve 14. [Figure 4] 10 is an explanatory diagram showing how the needle valve body 21 moves forward and backward in conjunction with the sliding operation of the heat adjustment lever 8. FIG. [Figure 5] 2 is an explanatory diagram showing the configuration of a valve head portion 22 of a needle valve element 21 in a flow rate adjustment valve 14 of the present embodiment. FIG. [Figure 6] 10 is an explanatory diagram showing the configuration of a valve head portion 22 of a needle valve element 21 in a flow rate adjustment valve 14 of a modified example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Fig. 1 is a perspective view showing the appearance of a gas stove 1 as an example of a cooking appliance according to this embodiment. The illustrated gas stove 1 is a tabletop stove that is placed on a kitchen stovetop and includes a box-shaped stove body 2 with an open top and a top plate 3 that is installed to cover the top of the stove body 2. A stove burner 4 that burns a mixture of fuel gas and air is installed inside the stove body 2, and the top of the stove burner 4 protrudes from an insertion hole formed in the top plate 3. In the illustrated example, two stove burners 4a and 4b are arranged on the left and right.

[0020] Trivets 5a and 5b are installed around each of the burners 4a and 4b on the top plate 3. These trivets are used to place cooking vessels such as pots for holding ingredients (foods to be cooked) above the burners 4a and 4b. The stove body 2 also has a built-in grill 6 (not shown) for grilling ingredients (foods to be cooked), and is equipped with a grill burner 6a that burns a mixture of fuel gas and air as its heat source.

[0021] A grill door 6d is provided on the front of the stove body 2, allowing the front of the grill 6 to be opened and closed. On the left and right sides of the grill door 6d, there are provided ignition / extinction buttons 7a, 7b, and 7g that the user operates to ignite and extinguish the two stove burners 4a, 4b and the grill burner 6a, respectively, as well as heat adjustment levers 8a, 8b, and 8g that are operated to adjust the heat.

[0022] In this embodiment, the ignition / extinction buttons 7a, 7b, and 7g are pressed toward the rear by the user. By pressing them from their initial position protruding toward the front to their full-extinction position at the rear, the corresponding burners 4a, 4b, and 6a are ignited. When the user releases the button, the ignition / extinction buttons 7a, 7b, and 7g are held in an intermediate position between their full-extinction and their initial positions, and combustion continues in the corresponding burners 4a, 4b, and 6a. When the button is then released by pressing it toward the rear again, the ignition / extinction buttons 7a, 7b, and 7g return to their initial positions, and the corresponding burners 4a, 4b, and 6a are extinguished. Furthermore, as will be described in detail later, the user can change the flame power of the corresponding burners 4a, 4b, and 6a by sliding the flame power adjustment levers 8a, 8b, and 8g left and right. Sliding the levers left decreases the flame power, and sliding the levers right increases the flame power.

[0023] 2 is an explanatory diagram showing a schematic diagram of the fuel gas supply path in the gas stove 1. The gas stove 1 of this embodiment is equipped with the two burners 4a, 4b and the grill burner 6a described above, and correspondingly, the gas passage 10 that supplies the fuel gas branches into three. That is, it branches into a left branch passage 11a corresponding to the left burner 4a, a right branch passage 11b corresponding to the right burner 4b, and a grill branch passage 11g corresponding to the grill burner 6a, and fuel gas is supplied to each of them. The burners 4a, 4b, and 6a of this embodiment correspond to the "combustion device" of the present invention.

[0024] In the left branch passage 11a, electromagnetic safety valve 12a and main valve 13a, which open and close the left branch passage 11a, and flow rate control valve 14a, which adjusts the flow rate of fuel gas in the left branch passage 11a, are provided in this order downstream. When electromagnetic safety valve 12a and main valve 13a are opened, fuel gas is injected from a nozzle (not shown) at the end of the left branch passage 11a at a flow rate corresponding to the opening of flow rate control valve 14a. The mixed gas, mixed with primary air for combustion, is supplied to the left stove burner 4a. This mixed gas is ejected from multiple flame ports in the left stove burner 4a, and combustion of the mixed gas is initiated by spark discharge from ignition plug 15a, heating the ingredients (food) in the cooking vessel above.

[0025] A thermocouple 16a is provided as a flame detector for detecting the combustion flame in the left stove burner 4a, and it is possible to detect ignition and extinguishing based on the electromotive force of the thermocouple 16a. In addition, a pot bottom temperature sensor 17a is provided that protrudes from the center of the left stove burner 4a and abuts against the bottom surface of the cooking vessel above, making it possible to detect the temperature of the cooking vessel.

[0026] Similarly, right branch passage 11b is provided with electromagnetic safety valve 12b, main valve 13b, and flow control valve 14b, as well as ignition plug 15b, thermocouple 16b, and pot bottom temperature sensor 17b corresponding to right stove burner 4b. Grill branch passage 11g is also provided with electromagnetic safety valve 12g, main valve 13g, and flow control valve 14g. Also, ignition plug 15g and thermocouple 16g corresponding to grill burner 6a are provided, and grill temperature sensor 18 is provided inside grill 6 to detect the temperature inside grill 6.

[0027] In this embodiment, the electromagnetic safety valves 12a, 12b, and 12g and the main valves 13a, 13b, and 13g can be opened and closed by pressing the corresponding on / off buttons 7a, 7b, and 7g. As described below, the flow rate control valves 14a, 14b, and 14g change their valve opening in conjunction with the sliding operation of the corresponding heat control levers 8a, 8b, and 8g. Each burner 4a, 4b, and 6a can adjust its heat during combustion by adjusting the valve opening (flow rate of fuel gas) of the corresponding flow rate control valve 14a, 14b, and 14g. The flow rate control valves 14a, 14b, and 14g in this embodiment correspond to the "gas flow rate control device" of the present invention. Furthermore, the flow rate control valves 14a, 14b, and 14g are basically the same. In the following description, when there is no need to distinguish between the flow rate control valves 14a, 14b, and 14g, they may be simply referred to as the "flow rate control valve 14."

[0028] FIG. 3 is an explanatory diagram showing the structure of the flow rate control valve 14. First, FIG. 3(a) shows a longitudinal cross-sectional view of the flow rate control valve 14. A substantially cylindrical valve chamber 20 is formed inside the flow rate control valve 14. This valve chamber 20 has a step 20c between a small diameter portion 20a and a large diameter portion 20b, which have different inner diameters. The downstream side of a branch passage 11 branching off from the gas passage 10 is connected to the end face of the small diameter portion 20a opposite the step 20c, and the upstream side of the branch passage 11 is connected to the circumferential surface of the large diameter portion 20b. That is, as shown by the outline arrow in the figure, fuel gas flows from the upstream side of the branch passage 11 into the large diameter portion 20b of the valve chamber 20 and flows out of the small diameter portion 20a via the step 20c to the downstream side of the branch passage 11.

[0029] A needle valve element 21 having a generally cylindrical shape is housed within the valve chamber 20, and as will be described in detail below, the flow rate of fuel gas supplied to the corresponding burner 4a, 4b, 6a through the branch passage 11 can be adjusted by moving the needle valve element 21 back and forth (left and right in the drawing) along the center line of the valve chamber 20. An O-ring 28 is fitted around the outer periphery of the needle valve element 21, and the presence of the O-ring 28 ensures airtightness between the inner periphery of the large-diameter portion 20b of the valve chamber 20 and the outer periphery of the needle valve element 21.

[0030] Furthermore, a pin 29 is fitted into the needle valve element 21 at the end (the left end in the figure) opposite the tip adjacent to the narrow-diameter portion 20a of the valve chamber 20, perpendicular to the advance / retract direction of the needle valve element 21. This pin 29 is inserted into a guide hole 30a formed in a guide plate 30 fixed to the flow rate control valve 14. Because the guide hole 30a is an elongated hole that is long in the advance / retract direction, movement of the pin 29 is guided along the guide hole 30a in the advance / retract direction. Furthermore, a drive cam 31 serving as a drive mechanism for driving the needle valve element 21 is provided rotatably about a support screw 32 that is perpendicular to the advance / retract direction. The drive cam 31 has a slit 31a through which the pin 29 is inserted, and the heat adjustment lever 8 described above is connected to the drive cam 31.

[0031] FIG. 3(b) shows a plan view of the needle valve element 21 and drive cam 31 from above, with the drive cam 31 shown in a see-through manner so that the needle valve element 21 can be seen. As shown, the slit 31a of the drive cam 31 is formed in an arc shape such that the distance from the support screw 32 changes continuously. Therefore, in the illustrated example, when the drive cam 31 rotates clockwise in the figure by sliding the heat adjustment lever 8, the pin 29 moves along the slit 31a toward the support screw 32, causing the needle valve element 21 to move toward the narrow-diameter portion 20a (to the right in the figure). On the other hand, when the drive cam 31 rotates counterclockwise in the figure by sliding the heat adjustment lever 8, the pin 29 moves away from the support screw 32 along the slit 31a, causing the needle valve element 21 to move to the opposite side of the narrow-diameter portion 20a (to the left in the figure). In this way, the sliding operation of the heat adjustment lever 8 is converted into the forward / backward movement of the needle valve element 21 via the drive cam 31. The needle valve element 21 does not have to be driven manually by the user sliding the heat control lever 8, but may be driven automatically by a motor or the like. The heat control lever 8 and drive cam 31 of this embodiment correspond to the "drive mechanism" of the present invention, and the pin 29 of this embodiment corresponds to the "connection part" of the present invention.

[0032] Figure 4 is an explanatory diagram showing how the needle valve element 21 moves back and forth in conjunction with the sliding operation of the flame power adjustment lever 8. Figures 4(a) to 4(c) show enlarged longitudinal cross-sectional views of the tip side of the needle valve element 21 adjacent to the small diameter portion 20a of the valve chamber 20. Figure 4(a) shows the needle valve element 21 when the flame power adjustment lever 8 is in the lowest flame power position, Figure 4(b) shows the needle valve element 21 when the flame power adjustment lever 8 is in the ignition position, and Figure 4(c) shows the needle valve element 21 when the flame power adjustment lever 8 is in the highest flame power position.

[0033] As shown in the figure, the needle valve body 21 has a valve head portion 22 at its tip close to the small diameter portion 20a that can be inserted into the small diameter portion 20a, and also has an abutment portion 23 that is located adjacent to the valve head portion 22 on the pin 29 side (left side in the figure), has a larger diameter than the valve head portion 22, and can abut against the step 20c. Furthermore, a through hole 24 is drilled in the needle valve body 21 on the pin 29 side of the abutment portion 23, perpendicular to the advancing / retracting direction of the needle valve body 21, and this through hole 24 communicates with an orifice 25 that is drilled along the advancing / retracting direction from the end face of the needle valve body 21 on the valve head portion 22 side.

[0034] When the flame adjustment lever 8 is at the lowest flame position, as shown in Figure 4(a), the entire valve head 22 of the needle valve element 21 is inserted into the small diameter portion 20a, and the abutment portion 23 abuts against the step 20c, thereby blocking the small diameter portion 20a. However, because the through hole 24 communicating with the orifice 25 of the needle valve element 21 opens at a position facing the upstream side of the branch passage 11 that communicates with the circumferential surface of the large diameter portion 20b of the valve chamber 20, even when the abutment portion 23 abuts against the step 20c, fuel gas flows from the upstream side of the branch passage 11 through the through hole 24 and the orifice 25 to the downstream side of the branch passage 11. Therefore, by adjusting the diameter of the orifice 25, a minimum flow rate of fuel gas can be ensured.

[0035] On the other hand, when the flame adjustment lever 8 is at the maximum flame position, as shown in Figure 4(c), the valve head 22 of the needle valve body 21 is not inserted into the small diameter portion 20a, leaving the small diameter portion 20a open. Therefore, the fuel gas that has flowed into the large diameter portion 20b from the upstream side of the branch passage 11 flows through the step 20c to the downstream side of the branch passage 11 that is connected to the small diameter portion 20a.

[0036] When the flame power adjustment lever 8 is between the lowest and highest flame power positions, part of the valve head portion 22 of the needle valve element 21 is inserted into the small diameter portion 20a, and when the flame power adjustment lever 8 is at the ignition position, in the example of Figure 4(b), approximately half of the valve head portion 22 is inserted into the small diameter portion 20a. At this time, the fuel gas that has flowed into the large diameter portion 20b from the upstream side of the branch passage 11 flows out to the downstream side of the branch passage 11 mainly through the gap between the small diameter portion 20a and the valve head portion 22.

[0037] If the inner diameter of the small diameter portion 20a and the outer diameter of the valve head portion 22 are each approximately constant, even if the insertion amount of the valve head portion 22 into the small diameter portion 20a increases or decreases, the gap (cross-sectional area of ​​the fuel gas passage) between the small diameter portion 20a and the valve head portion 22 does not change significantly, but as the insertion amount increases, the flow resistance of the fuel gas increases and the flow rate of the fuel gas decreases. Therefore, it is possible to adjust the flow rate of the fuel gas by the insertion amount of the valve head portion 22 into the small diameter portion 20a, which is linked to the movement of the needle valve element 21 in the forward and backward directions.

[0038] The graph in Figure 4(d) illustrates the relationship between the insertion depth of the valve head section 22 into the narrow diameter section 20a and the fuel gas flow rate when the inner diameter of the narrow diameter section 20a and the outer diameter of the valve head section 22 are both substantially constant. The horizontal axis represents the insertion depth L of the valve head section 22 into the narrow diameter section 20a, and the vertical axis represents the fuel gas flow rate F. The insertion depth L of the valve head section 22 into the narrow diameter section 20a is plotted in correspondence with Figures 4(a) to 4(c), with the insertion depth L increasing to the left on the horizontal axis (see Figure 4(a)) and decreasing to the right on the horizontal axis (see Figure 4(c)). As the insertion depth L of the valve head section 22 into the narrow diameter section 20a increases (moving the flame power adjustment lever 8 to the low side), the resistance to the passage of fuel gas through the gap between the narrow diameter section 20a and the valve head section 22 increases, resulting in a decrease in the fuel gas flow rate F.

[0039] In this type of flow control valve 14, the stop position of the needle valve element 21, which is linked to the sliding operation of the heat power adjustment lever 8, may deviate from the target position. As described above, the sliding operation of the heat power adjustment lever 8 is converted into the movement of the needle valve element 21 in the forward and backward directions via the drive cam 31. To allow the pin 29 inserted into the end of the needle valve element 21 to move smoothly along the slit 31a of the drive cam 31, a clearance is provided between the pin 29 and the slit 31a (see FIG. 3(b)). Due to this clearance, the stop position of the needle valve element 21 deviates when the heat power adjustment lever 8 is operated from low to high and when it is operated from high to low. If this causes a change in the insertion amount L of the valve head portion 22 into the small diameter portion 20a, the flow rate F of the fuel gas fluctuates, causing the heat of the burners 4a, 4b, and 6a to become unstable.

[0040] For example, as shown in Figure 4(d), if the insertion amount L of the valve head 22 corresponding to the ignition position of the heat control lever 8 deviates by ±α from the target insertion amount Li, the fuel gas flow rate F at ignition will fluctuate between F min (Li + α), which corresponds to an increase in insertion amount L, and F max (Li - α), which corresponds to a decrease in insertion amount L. If the fuel gas flow rate F at ignition is insufficient at F min, ignition failure may occur. Conversely, if the fuel gas flow rate F at ignition is excessive at F max, flames may overflow from the bottom of the cooking vessel. Therefore, the flow control valve 14 of this embodiment employs the following configuration to stabilize the fuel gas flow rate at a specific flow rate corresponding to ignition, regardless of the position of the needle valve element 21 (the insertion amount of the valve head 22 into the narrow-diameter portion 20a) within the valve chamber 20.

[0041] FIG. 5 is an explanatory diagram showing the configuration of the valve head portion 22 of the needle valve element 21 in the flow rate control valve 14 of this embodiment. First, FIG. 5(a) shows an enlarged longitudinal cross-sectional view of the outer peripheral shape of the valve head portion 22. As shown in the figure, the valve head portion 22 of this embodiment has a tip straight portion 22a with a substantially constant outer diameter, which is provided at the tip (right end in the figure) opposite the abutment portion 23; a reduced-diameter portion 22b, which is provided closer to the abutment portion 23 than the tip straight portion 22a (left side in the figure) and has an outer diameter that decreases toward the abutment portion 23; an expanded-diameter portion 22c, which is provided closer to the abutment portion 23 than the reduced-diameter portion 22b and has an outer diameter that increases toward the abutment portion 23; and a base straight portion 22d, which is provided closer to the abutment portion 23 than the expanded-diameter portion 22c and has a substantially constant outer diameter. The angle θ formed between the reduced-diameter portion 22b and the expanded-diameter portion 22c is an obtuse angle. The length of the reduced diameter portion 22b in the advance / retract direction (left / right direction in the figure) of the valve head portion 22 is longer than the length of the enlarged diameter portion 22c. Furthermore, the outer diameter of the tip straight portion 22a is smaller than the outer diameter of the base straight portion 22d.

[0042] 5(b) shows an enlarged longitudinal cross-sectional view of the valve head portion 22 inserted into the narrow diameter portion 20a. FIG. 5(b) illustrates a state in which the valve head portion 22 is inserted into the narrow diameter portion 20a to the target insertion amount Li at the time of ignition. The inner diameter of the narrow diameter portion 20a in this embodiment is substantially constant. If the position of the valve head portion 22 inserted into the narrow diameter portion 20a adjacent to the step 20c of the valve chamber 20 is defined as an adjacent point P, the target adjacent point Pi of the valve head portion 22 corresponding to the target insertion amount Li at the time of ignition is set to approximately the center of the reduced diameter portion 22b in the advancing / retracting direction of the needle valve element 21 (the left-right direction in the figure), as shown in the figure.

[0043] The graph in Fig. 5(c) shows the relationship between the insertion amount of the valve head section 22 into the narrow diameter section 20a and the flow rate of the fuel gas in the flow control valve 14 of this embodiment. As with Fig. 4(d) described above, the horizontal axis represents the insertion amount L of the valve head section 22 into the narrow diameter section 20a, and the vertical axis represents the flow rate F of the fuel gas. Before and after the target insertion amount Li at the time of ignition, the adjacent point P of the valve head section 22 adjacent to the step 20c fluctuates along the narrowed diameter section 22b (see Fig. 4(b)). Furthermore, at the narrowed diameter section 22b, even if the insertion amount into the narrow diameter section 20a increases, an increase in the resistance to the passage of the fuel gas in the gap between the narrow diameter section 20a and the valve head section 22 is suppressed by the widening of the gap between the narrow diameter section 20a and the narrowed diameter section 22b. Therefore, a decrease in the flow rate F of the fuel gas is suppressed and kept substantially constant.

[0044] Therefore, as shown in Figure 5(c), whether the insertion amount L of the valve head portion 22 corresponding to the ignition position of the heat power adjustment lever 8 is Li+α, which is shifted to the increasing side relative to the target insertion amount Li, or Li-α, which is shifted to the decreasing side, the flow rate F of the fuel gas is maintained at the target flow rate Fi, thereby stabilizing the heat power of the burners 4a, 4b, and 6a.

[0045] In the tip straight section 22a of the valve head section 22, which is closer to the tip than the reduced diameter section 22b (the side where the insertion amount L is smaller), as the insertion amount into the thin diameter section 20a increases, the resistance to the passage of fuel gas increases without changing the gap between the thin diameter section 20a and the tip straight section 22a, resulting in a decrease in the fuel gas flow rate F. In addition, in the expanded diameter section 22c of the valve head section 22, which is closer to the abutment section 23 than the reduced diameter section 22b (the side where the insertion amount L is larger), as the insertion amount into the thin diameter section 20a increases and the gap between the thin diameter section 20a and the expanded diameter section 22c narrows, the flow rate F of fuel gas tends to decrease as the resistance to the passage of fuel gas increases. Furthermore, in the base-end straight portion 22d of the valve head portion 22, which is closer to the abutment portion 23 than the enlarged diameter portion 22c, when the insertion amount into the narrow diameter portion 20a increases, the resistance to the passage of the fuel gas increases, although the gap between the narrow diameter portion 20a and the base-end straight portion 22d does not change, and the flow rate F of the fuel gas decreases.

[0046] As described above, in the flow rate control valve 14 of this embodiment, the inner diameter of the small diameter portion 20a of the valve chamber 20 is approximately constant, whereas the valve head portion 22 of the needle valve element 21 that can be inserted into the small diameter portion 20a is provided with, in this order from the tip side toward the abutment portion 23, a tip straight portion 22a with an approximately constant outer diameter, a reduced diameter portion 22b with a smaller outer diameter, and an expanded diameter portion 22c with an larger outer diameter. The angle formed by the reduced diameter portion 22b and the expanded diameter portion 22c is an obtuse angle.

[0047] In the flow control valve 14 of this embodiment, as the valve head section 22 is inserted into the small diameter section 20a, first, in the tip straight section 22a, as the insertion amount into the small diameter section 20a increases, the resistance to the passage of fuel gas increases even though the gap (the fuel gas passage cross-sectional area) between the small diameter section 20a and the tip straight section 22a remains unchanged, resulting in a decrease in the flow rate of fuel gas. Next, in the contracted diameter section 22b, even if the insertion amount into the small diameter section 20a increases, the increase in the resistance to the passage of fuel gas is suppressed by the expansion of the gap between the small diameter section 20a and the contracted diameter section 22b, thereby suppressing a decrease in the flow rate of fuel gas and making it possible to maintain a substantially constant flow rate. As a result, even if the stopping position of the needle valve element 21 deviates from the target position, the flow rate of fuel gas can be stabilized within the range in which the insertion amount of the contracted diameter section 22b into the small diameter section 20a changes in accordance with the deviation of the stopping position. In particular, by stabilizing the flow rate of fuel gas at a specific flow rate at the time of ignition, it is possible to prevent insufficient fuel gas flow rate resulting in poor ignition, or excessive fuel gas flow rate resulting in flames overflowing from the bottom of the cooking vessel, thereby stabilizing the thermal power of burners 4a, 4b, and 6a.

[0048] Furthermore, by providing the expanded diameter portion 22c at an obtuse angle closer to the abutment portion 23 than the reduced diameter portion 22b, when the insertion of the valve head portion 22 into the small diameter portion 20a transitions from the reduced diameter portion 22b to the expanded diameter portion 22c, the resistance to the passage of the fuel gas gradually increases, and a sudden decrease in the flow rate of the fuel gas is less likely to occur, compared to when the angle is acute. Therefore, a sudden change in the heating power of the burners 4a, 4b, and 6a can be suppressed. Furthermore, in the flow rate control valve 14 of this embodiment, since the needle valve element 21 is manually driven by the user sliding the heating power adjustment lever 8 as described above, when the expanded diameter portion 22c is at an obtuse angle with respect to the reduced diameter portion 22b, an increase in the operating load (uncomfortable operation) caused by the expanded diameter portion 22c coming into contact with the step 20c of the valve chamber 20 as the valve head portion 22 is inserted into the small diameter portion 20a can be suppressed compared to when the angle is acute.

[0049] Furthermore, in the flow rate control valve 14 of this embodiment, the length of the reduced diameter portion 22b in the advance / retract direction of the valve head portion 22 is longer than the length of the expanded diameter portion 22c. By setting the reduced diameter portion 22b to be long in this manner, even if the stopping position of the needle valve element 21 deviates from the target position, the reduced diameter portion 22b can suppress fluctuations in the resistance to the passage of the fuel gas that accompany the deviation of the stopping position, thereby ensuring a wide range in which the flow rate of the fuel gas can be kept approximately constant.

[0050] Furthermore, in the flow control valve 14 of this embodiment, a base-end straight portion 22d with a substantially constant outer diameter is provided on the valve head portion 22 closer to the abutment portion 23 than the enlarged-diameter portion 22c, and the outer diameter of the tip straight portion 22a is smaller than the outer diameter of the base-end straight portion 22d. Setting the outer diameter of the tip straight portion 22a to a small value in this manner makes it less likely for the tip straight portion 22a to come into contact with the step 20c when the user manually drives the needle valve element 21 by sliding the heat adjustment lever 8 and the tip straight portion 22a begins to enter the small-diameter portion 20a, thereby suppressing an increase in the operating load (uncomfortable operation). Furthermore, setting the outer diameter of the base-end straight portion 22d to a large value suppresses variation in the position of the valve head portion 22 in the radial direction of the small-diameter portion 20a when the valve head portion 22 is inserted into the small-diameter portion 20a up to the base-end straight portion 22d, thereby enabling stabilization of the low-side heating power of the burners 4a, 4b, and 6b.

[0051] The flow rate control valve 14 of the above-described embodiment also has the following modifications. The following describes the modifications, focusing on the differences from the above-described embodiment. In the description of the modifications, the same components as those in the above-described embodiment are given the same reference numerals and will not be described again.

[0052] In the flow rate control valve 14 of the above-described embodiment, only one combination of the reduced diameter portion 22b and the expanded diameter portion 22c is provided in the valve head portion 22. However, the combination of the reduced diameter portion 22b and the expanded diameter portion 22c is not limited to one, and multiple combinations may be provided in the forward and backward direction of the valve head portion 22. In the flow rate control valve 14 of the modified example, two combinations of the reduced diameter portion 22b and the expanded diameter portion 22c are provided in the forward and backward direction.

[0053] 6A and 6B are explanatory diagrams showing the configuration of the valve head portion 22 of the needle valve element 21 in a modified flow rate control valve 14. First, Fig. 6A shows an enlarged longitudinal cross-sectional view of the outer peripheral shape of the valve head portion 22. As shown in the figure, the valve head portion 22 of the modified example is provided with, in order from the tip side toward the abutment portion 23 side, a tip straight portion 22a, a first reduced diameter portion 22b1, a first expanded diameter portion 22c1, a second reduced diameter portion 22b2, a second expanded diameter portion 22c2, and a base straight portion 22d. The angle θ1 formed between the first reduced diameter portion 22b1 and the first expanded diameter portion 22c1 is an obtuse angle, and the angle θ2 formed between the second reduced diameter portion 22b2 and the second expanded diameter portion 22c2 is an obtuse angle. Furthermore, the angle θ3 formed between the first expanded diameter portion 22c1 and the second reduced diameter portion 22b2 is an obtuse angle, and the angle θ4 formed between the second expanded diameter portion 22c2 and the base end straight portion 22d is also an obtuse angle.

[0054] In addition, when the valve head section 22 is inserted into the narrow diameter section 20a up to the target insertion amount Li at the time of ignition, the target adjacent point Pi of the valve head section 22 adjacent to the step 20c of the valve chamber 20 is set to approximately the center of the first reduced diameter section 22b1 in the forward / backward direction. Furthermore, the modified stove burners 4a and 4b are equipped with an automatic rice cooking mode, and when the valve head section 22 is inserted into the narrow diameter section 20a up to the target insertion amount Lr at the time of rice cooking, which corresponds to the automatic rice cooking position of the heat adjustment lever 8, the target adjacent point Pr of the valve head section 22 adjacent to the step 20c of the valve chamber 20 is set to approximately the center of the second reduced diameter section 22b2 in the forward / backward direction.

[0055] The graph in Fig. 6(b) shows the relationship between the insertion amount of the valve head section 22 into the narrow diameter section 20a and the flow rate of fuel gas in the modified flow rate control valve 14. As with Fig. 5(c) described above, the horizontal axis represents the insertion amount L of the valve head section 22 into the narrow diameter section 20a, and the vertical axis represents the flow rate F of fuel gas. Before and after the target insertion amount Li at the time of ignition, the adjacent point P of the valve head section 22 adjacent to the step 20c fluctuates along the first reduced diameter section 22b1. At the first reduced diameter section 22b1, even if the insertion amount into the narrow diameter section 20a increases, the increase in the resistance to the passage of fuel gas in the gap between the narrow diameter section 20a and the valve head section 22 is suppressed by the widening of the gap between the narrow diameter section 20a and the first reduced diameter section 22b1. Therefore, the decrease in the flow rate F of fuel gas is suppressed and the flow rate F of fuel gas is maintained at the target flow rate Fi. Similarly, adjacent point P of valve head section 22 fluctuates along second reduced diameter section 22b2 around target insertion amount Lr during rice cooking. At second reduced diameter section 22b2, even if the insertion amount into thin diameter section 20a increases, an increase in the resistance to fuel gas passage in the gap between thin diameter section 20a and valve head section 22 is suppressed by the widening of the gap between thin diameter section 20a and second reduced diameter section 22b2, so that a decrease in fuel gas flow rate F is suppressed and maintained at target flow rate Fr.

[0056] In the flow rate control valve 14 of the above-described modified example, the valve head 22 is provided with a combination of the first reduced diameter portion 22b1 and the first expanded diameter portion 22c1, and a combination of the second reduced diameter portion 22b2 and the second expanded diameter portion 22c2. This configuration allows the first reduced diameter portion 22b1 to suppress fluctuations in the resistance to the passage of fuel gas, stabilizing the fuel gas flow rate at the target flow rate during ignition, even if the stopping position of the needle valve element 21 deviates from the target position during ignition. This stabilizes the heating power during ignition. Furthermore, even if the stopping position of the needle valve element 21 deviates from the target position during rice cooking, the second reduced diameter portion 22b2 to suppress fluctuations in the resistance to the passage of fuel gas, stabilizing the fuel gas flow rate at the target flow rate during rice cooking. This prevents undercooking due to insufficient cooking and scorching due to overcooking in the automatic rice cooking mode, thereby stabilizing the heating power during rice cooking. By stabilizing the heat power at two stages (when lighting and when cooking rice) in this way, the convenience of adjusting the heat power of the gas stove 1 can be improved.

[0057] Furthermore, in the modified flow rate control valve 14, the angle between the first enlarged diameter portion 22c1 and the second reduced diameter portion 22b2 is an obtuse angle, and therefore, when the insertion of the valve head portion 22 into the narrow diameter portion 20a transitions from the first enlarged diameter portion 22c1 to the second reduced diameter portion 22b2, the change in the resistance to the passage of the fuel gas is gradual compared to when the angle is acute, and sudden fluctuations in the flow rate of the fuel gas are less likely to occur, thereby suppressing sudden changes in thermal power.

[0058] The above describes the flow rate control valve 14 in the embodiment and modified examples, but the present invention is not limited to the above embodiment and modified examples, and can be embodied in various forms without departing from the spirit of the present invention.

[0059] For example, in the above-described embodiment, the downstream side of the branch passage 11 is connected to the end face of the small diameter portion 20a of the valve chest 20 opposite the step 20c, and the upstream side of the branch passage 11 is connected to the circumferential surface of the large diameter portion 20b. However, conversely, the upstream side of the branch passage 11 may be connected to the end face of the small diameter portion 20a opposite the step 20c, and the downstream side of the branch passage 11 may be connected to the circumferential surface of the large diameter portion 20b. Even in this case, the same effects as those of the above-described embodiment can be obtained.

[0060] In the above-described embodiment, the reduced diameter portion 22b and the expanded diameter portion 22c of the valve head portion 22 of the needle valve element 21 are adjacent to each other. However, the reduced diameter portion 22b and the expanded diameter portion 22c do not have to be adjacent to each other, and a straight portion with a substantially constant outer diameter may be provided between the reduced diameter portion 22b and the expanded diameter portion 22c. By transitioning the valve head portion 22 into the small diameter portion 20a from the reduced diameter portion 22b to the expanded diameter portion 22c via the straight portion, the change in the resistance to the passage of fuel gas becomes more gradual than when the valve head portion 22b transitions directly from the reduced diameter portion 22b to the expanded diameter portion 22c, thereby suppressing abrupt fluctuations in the flow rate of fuel gas. Similarly, a straight portion with a substantially constant outer diameter may be provided between the first expanded diameter portion 22c1 and the second reduced diameter portion 22b2 of the valve head portion 22 of the modified example. [Explanation of symbols]

[0061] 1...Gas stove, 2...Stove body, 3...Top plate, 4...Stove burner, 5...Trivet, 6...Grill, 6a...grill burner, 6d...grill door, 7...fire extinguishing button, 8...heat adjustment lever, 10...gas passage, 11...branch, 12...Electromagnetic safety valve, 13...Main valve, 14...Flow control valve, 15...Ignition plug, 16a...Thermocouple, 17...Pot bottom temperature sensor, 18...grill temperature sensor, 20...valve chamber, 20a...thin diameter portion, 20b...large diameter portion, 20c...step, 21...needle valve body, 22... valve head portion, 22a... tip straight portion, 22b... reduced diameter portion, 22c...expanded diameter portion, 22d...base end straight portion, 23...abutment portion, 24...through hole, 25...orifice, 28...O-ring, 29... pin, 30... guide plate, 30a... guide hole, 31...Drive cam, 31a...Slit, 32...Support shaft screw.

Claims

1. A gas flow rate control device is provided in a gas passage that supplies fuel gas to a combustion device, the gas flow rate control device comprising: a substantially cylindrical needle valve element housed in a substantially cylindrical valve chamber; and the gas flow rate control device controls a flow rate of the fuel gas supplied to the combustion device by moving the needle valve element in a forward and backward direction along a center line of the valve chamber, the valve chamber has a step between a small diameter portion and a large diameter portion having different inner diameters, and the gas passage communicates with an end face of the small diameter portion opposite to the step and a peripheral surface of the large diameter portion, the needle valve body has a valve head portion at one end adjacent to the narrow diameter portion, the valve head portion being insertable into the narrow diameter portion, and a connection portion at the other end opposite to the valve head portion, the connection portion being connected to a drive mechanism that drives the needle valve body; The inner diameter of the narrow diameter portion is substantially constant, The valve head a tip straight portion provided at the tip and having a substantially constant outer diameter; a tapered portion provided closer to the connection portion than the tip straight portion and having an outer diameter that decreases toward the connection portion; an expanded diameter portion that is provided closer to the connection portion than the reduced diameter portion and has an outer diameter that increases toward the connection portion; Equipped with The angle formed between the reduced diameter portion and the expanded diameter portion is an obtuse angle. A gas flow rate adjusting device characterized by:

2. The gas flow rate regulator according to claim 1, The length of the reduced diameter portion in the advancing / retracting direction of the valve head is longer than the length of the expanded diameter portion. A gas flow rate adjusting device characterized by:

3. The gas flow rate regulator according to claim 1 or 2, The valve head portion is provided with a plurality of combinations of the reduced diameter portion and the expanded diameter portion in the advancing / retracting direction, The combinations are different, and the angle formed between the adjacent enlarged diameter portion and the adjacent reduced diameter portion is an obtuse angle. A gas flow rate adjusting device characterized by:

4. The gas flow rate regulator according to claim 1 or 2, a proximal straight portion having a substantially constant outer diameter is provided on the valve head portion closer to the connecting portion than the enlarged diameter portion, The outer diameter of the tip straight portion is smaller than the outer diameter of the base straight portion. A gas flow rate adjusting device characterized by:

5. 3. A cooking appliance comprising the gas flow rate regulator according to claim 1 or 2, and for heating food by combustion in the combustion device.

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