JP5674743B2 - Gas stove - Google Patents

Description

  The present invention relates to a gas stove that includes a burner that heats a cooking container placed on the virtues on a top plate and a pan bottom temperature sensor that detects the temperature of the cooking container.

  Conventionally, as this type of gas stove, in order to perform temperature control to maintain the temperature of the cooking container within a predetermined set temperature range, the detected temperature of the pan bottom temperature sensor is the upper limit temperature of the set temperature range in the gas supply path to the burner. A motor-operated valve that opens when the temperature detected by the pan bottom temperature sensor falls below the lower limit temperature of the set temperature range, and an orifice in parallel with the motor-operated valve. What is provided is known (see, for example, Patent Document 1).

  In this case, when the temperature detected by the pan bottom temperature sensor exceeds the upper limit temperature, the electric valve is closed and the amount of gas supplied to the burner is limited to the minimum amount specified by the orifice. When the temperature of the container is lowered, the temperature detected by the pan bottom temperature sensor is equal to or lower than the lower limit temperature, and the motor-operated valve is opened, the burning power of the burner becomes high and the temperature of the cooking container rises.

  Here, in order to reduce the undershoot of the cooking vessel temperature relative to the lower limit temperature and improve the temperature control performance, shorten the opening operation time required for switching the motor-operated valve from the closed state to the open state. Is desired. However, if the opening operation time is shortened and the amount of gas supplied to the burner is suddenly increased, the amount of primary air supplied to the burner will not increase suddenly due to inertia, so the flame will lift due to a shortage of primary air. It becomes a state and spreads outside, so that it becomes easy to generate a so-called flame overflow in which a flame overflows from the bottom surface of the cooking container.

  Therefore, conventionally, the opening time of the motor-operated valve is made relatively long, and the amount of gas supplied to the burner is gradually increased to prevent the overflow of the flame. Therefore, the undershoot of the cooking vessel temperature with respect to the lower limit temperature cannot be made sufficiently small.

  By the way, the present inventor has come to know the following as a result of diligent efforts. That is, when the temperature of the flame outlet portion of the burner is lowered, as will be described in detail later, even if the opening time of the motor-operated valve is shortened, it is difficult for flame overflow to occur.

JP 2010-139189 A

  An object of the present invention is to provide a gas stove that can improve the temperature control performance by avoiding unnecessarily prolonging the opening time of the motor-operated valve without causing an overflow of the flame based on the above-described knowledge. It is said.

  In order to solve the above-mentioned problems, the present invention is a gas stove comprising a burner for heating a cooking container placed on the virtues on a top plate, and a pan bottom temperature sensor for detecting the temperature of the cooking container. The gas supply passage is closed when the temperature detected by the pan bottom temperature sensor is equal to or higher than the upper limit temperature of the preset temperature range, and is opened when the temperature detected by the pan bottom temperature sensor falls below the lower limit temperature of the preset temperature range. In a valve having a motor-driven motor driven by a motor and an orifice parallel to the motor-operated valve, the opening operation time required for switching the motor-operated valve from the closed state to the open state is determined by It is characterized by being variable stepwise or continuously according to the temperature of the flaming portion so as to become shorter as the temperature becomes lower.

  Here, when the temperature of the flame opening is low, even if the opening time of the motor-operated valve is shortened and the amount of gas supplied to the burner is rapidly increased, no flame overflow occurs. Therefore, if the opening operation time of the motor-operated valve is varied so as to become shorter as the temperature of the flame opening becomes lower, it is possible to avoid unnecessarily prolonging the opening operation time without causing a flame overflow and improve the temperature control performance. .

  “Varying the opening operation time stepwise according to the temperature of the flaming portion” includes changing the opening operation time by one step depending on whether the temperature of the flaming portion is equal to or higher than a predetermined threshold value. It is.

  Further, since the temperature of the burner portion of the burner becomes higher as the elapsed time from the start of combustion of the burner becomes longer, the elapsed time from the start of combustion of the burner may be used as a parameter representing the temperature of the portion of the burner. This eliminates the need for a sensor that actually measures the temperature of the flaming portion, thereby reducing costs.

Sectional drawing of the principal part of the gas stove of embodiment of this invention. Sectional drawing of the motor operated valve used with the gas stove of FIG. The flowchart which shows the content of the temperature control performed with the gas stove of FIG. The flowchart which shows the content of the valve opening control of the motor operated valve in the temperature control of FIG. The graph explaining the specific method of changing the opening operation time of a motor operated valve. The graph which shows the change by the temperature of the flame part of the excess air ratio immediately after opening a motor operated valve by short opening operation time.

  Referring to FIG. 1, reference numeral 1 denotes a top plate that covers the upper surface of a stove body (not shown). The top plate 1 is provided with a burner opening 1a, and a burner 2 is installed on the stove body so as to face the burner opening 1a. On the top plate 1, a virtues 3 formed by attaching a plurality of virtuosity claws 32 radially to an annular virtuosity frame 31 so as to surround the burner 2, and cooking containers such as pots placed on the virtues 3 Is heated by the burner 2.

  The burner 2 includes an annular burner body 22 connected to the mixing tube 21, an annular burner cap 24 that is placed on the burner body 22, and defines a flame opening 23 between the burner body 22, and the burner cap 24 And an annular secondary air guide plate 25 that defines a secondary air passage between the burner cap 24 and a known annular burner. An ignition electrode 26 and a thermocouple 27 for flame detection are attached to the outer periphery of the burner 2.

  In the gas supply path 4 to the burner 2, in order from the upstream side, an electromagnetic safety valve 41 that closes when the electromotive force of the thermocouple 27 falls below a predetermined level due to the misfire of the burner 2, and the front surface of the stove body are not shown. A manual main valve 42 opened by an ignition operation by an operation button and closed by a fire extinguishing operation, a manual flow rate adjustment valve 43 interlocked with a heating power adjustment lever (not shown) on the front of the stove body, an electric valve 44, an electric valve An orifice 45 in parallel with the valve 44 is provided.

  As shown in FIG. 2, the electric valve 44 includes a valve housing 441 having a gas inlet 441a and a gas outlet 441b. Inside the valve housing 441 are a valve chamber 441c communicating with the gas inlet 441a, a valve seat 441e provided on one end wall 441d of the valve chamber 441c, and a valve chamber 441c and a gas outlet 441b formed in the valve seat 441e. And a valve hole 441f that communicates with each other.

  The valve housing 441 is formed with a passage hole 441g in parallel with the valve hole 441f that communicates the valve chamber 441c and the gas outlet 441b, and an orifice 45 is provided in the passage hole 441g. That is, a part of the passage hole 441 g is formed in a small diameter hole that becomes the orifice 45.

  The motorized valve 44 further includes a diaphragm 442 mounted on the other end face of the valve chamber 441c, a valve body 443 provided on the diaphragm 442 so as to face the valve seat 441e, a motor 444 including a stepping motor, and the like. A feed screw mechanism 445 that displaces the diaphragm 442 so that the valve body 443 approaches and separates from the valve seat 441e by forward and reverse rotation of the motor 444 is provided.

  A diaphragm cover 446 is attached to the outer surface of the valve casing 441 so that the periphery of the diaphragm 442 is sandwiched between the valve casing 441 and a motor 444 is mounted on the outer end of the diaphragm cover 446. The feed screw mechanism 445 includes a screw shaft 445a on the output shaft of the motor 444 and a nut 445b screwed to the screw shaft 445a. The nut 445b is slidably accommodated in a state in which the nut 445b is prevented from rotating around the diaphragm cover 446, and the nut 445b moves forward and backward in the axial direction by forward and reverse rotation of the screw shaft 445a by the motor 444.

  A metal or hard resin plate 442 a that contacts the nut 445 b is fixed to the outer surface of the diaphragm 442. Then, the diaphragm 442 is urged toward the nut 445b by the spring 442b, and the diaphragm 442, that is, the closed side where the valve body 443 approaches the valve seat 441e is separated from the valve seat 441e following the forward and backward movement of the nut 445b. Displacement to the open side.

  The valve body 443 can be directly connected to the nut 445b, and the diaphragm 442 can be omitted. However, when the diaphragm 442 is provided as in the present embodiment, the arrangement portion of the feed screw mechanism 445 is hermetically sealed by the diaphragm 442 with respect to the valve chamber 441c, so that the feed screw mechanism 445 prevents gas leakage to the motor 444. It is not necessary to incorporate a seal member. Therefore, power loss due to friction with the seal member does not occur and power consumption can be reduced, which is advantageous when the power source is a dry battery.

  In addition, the gas stove of the present embodiment includes a pan bottom temperature sensor 5 that protrudes above the burner 2 through a burner inner space surrounded by the burner 2. The pan bottom temperature sensor 5 includes a support pipe 51 that is vertically long and inserted into the burner inner space, and a thermal head 52 that is supported by the upper end of the support pipe 51. The support pipe 51 is fixed to the burner 2 with a fixture (not shown). The thermal head 52 includes a heat collecting plate 52a that comes into contact with the bottom surface of the cooking container, an inner cylinder 52b whose upper end is closed by the heat collecting plate 52a, and an outer cylinder 52c for heat insulation that surrounds the inner cylinder 52b. A thermal element 53 such as a thermistor for detecting the temperature of the cooking container is attached to the lower surface of the hot plate 52a via the heat collecting plate 52a.

  The inner cylinder 52b is externally inserted in a spring receiver 54a fixed to the upper end of the support pipe 51 so as to be movable up and down. A spring 54 is interposed between the spring receiver 54a and the heat collecting plate 52a so as to support the support pipe. A thermal head 52 is biased upward by a spring 54 with respect to 51. Further, a stepped portion 52d having a reduced diameter is formed at the lower end portion of the inner cylinder 52b. When the cooking container is not placed on Gotoku 3, the thermal head 52 contacts the lower surface of the spring receiver 54a with the stepped portion 52d. It is held at the upper moving end position regulated by contact. At the upper moving end position, the thermal head 52 protrudes above the virtues 3. When the cooking container is placed on Gotoku 3, the thermal head 52 comes into contact with the bottom surface of the cooking container and is pushed down against the biasing force of the spring 54, and the heat collecting plate 52a is cooked by the compression reaction force of the spring 54. The bottom surface of the container is surely contacted.

  The lead wire 53a extending from the heat sensitive element 53 is inserted into the support pipe 51, pulled out from the lower end thereof, and connected to the controller 6 as control means (see FIG. 1). A heat insulating coating 53b is externally attached to the lead wire 53a.

  The controller 6 performs temperature control based on the temperature detected by the pan bottom temperature sensor 5 (thermal element 53) when the temperature control mode is selected as the heating mode by the operation unit on the stove front surface. In the temperature control, as shown in FIG. 3, in STEP 1, it is determined whether or not the detected temperature T of the pan bottom temperature sensor 5 is equal to or higher than the upper limit temperature YTmax of a predetermined set temperature range, and when T ≧ YTmax, Proceeding to STEP 2, the motor-operated valve 44 is closed. Next, proceeding to STEP 3, it is determined whether or not the detected temperature T of the pan bottom temperature sensor 5 has become equal to or lower than the lower limit temperature YTmin of the set temperature range. When T ≦ YTmin, the routine proceeds to STEP 4 and the motorized valve 44 is opened. After making the valve, return to STEP1.

  When the motor-operated valve 44 is closed, the amount of gas supplied to the burner 2 is limited to the minimum gas amount defined by the orifice 45, and the cooking vessel temperature detected by the pan bottom temperature sensor 5 gradually decreases due to the reduction in the heating power of the burner 2. . Moreover, when the motor-operated valve 44 is opened, the amount of gas supplied to the burner 2 increases, and the cooking vessel temperature gradually rises. Here, in order to reduce the undershoot of the cooking vessel temperature with respect to the lower limit temperature YTmin and improve the temperature control performance, the opening operation time required for switching the motor-operated valve 44 from the closed state to the open state is shortened. It is desirable to do. However, when the opening operation time is shortened and the amount of gas supplied to the burner 2 is suddenly increased, the amount of primary air supplied to the burner 2 does not increase rapidly due to the influence of inertia. The excess air ratio (primary air amount / theoretical air amount) of the jetted air-fuel mixture temporarily becomes too small, and the flame becomes lifted and spreads outward and tends to overflow.

  The inventor of the present application uses an electric valve 44 having a stroke from the fully closed position to the fully open position of about 1 mm, and mixing immediately after the electric valve 44 is opened with a relatively short opening operation time of about 0.1 seconds. A test for measuring the excess air ratio is performed by changing the temperature of the flame port 23 (specifically, the temperature in the vicinity of the flame port 23 of the burner cap 24), and the result shown by the a line in FIG. 6 is obtained. It was. In addition, the b line of FIG. 6 has shown the excess air ratio at the time of the stable combustion in the valve opening state of the motor operated valve 44. FIG. Here, when the temperature of the flame opening 23 is high, the mixture passage area of the flame opening 23 becomes small due to the thermal expansion of the meat part other than the flame opening 23 of the burner cap 22, and the pressure of the mixture inside the burner increases. Thus, the suction force of the primary air into the mixing pipe 21 is reduced, and the drop in the excess air ratio immediately after the motor-operated valve 44 is opened increases. On the other hand, when the temperature of the flame opening 23 is lowered, the drop of the excess air ratio immediately after the opening of the motor-operated valve 44 becomes relatively small.

  The line c in FIG. 6 shows the excess air ratio that becomes the flame overflow limit when a flame overflow is defined as a state in which the flame spreads outward by 10% or more compared to the flame at the time of stable combustion when the motor-operated valve 44 is open. When the excess air ratio falls below the c line, flame overflow occurs. When the temperature of the flame opening 23 becomes lower, the a line in FIG. 6 exceeds the c line, and even if the opening time of the motor operated valve 44 is shortened, the flame does not overflow.

  Therefore, in the valve opening control of the electric valve 44 in STEP 4 of FIG. 3, the opening operation time of the electric valve 44 is variable according to the temperature of the flame mouth 23 portion so as to become shorter as the temperature of the flame mouth 23 portion becomes lower. By doing so, it is possible to avoid unnecessarily prolonging the opening operation time without causing overflow of the flame, and the temperature control performance is improved.

  Here, it is also possible to detect the temperature of the flame port 23 by a sensor, but the temperature of the flame port 23 increases as the elapsed time from the start of combustion of the burner 2 becomes longer. The elapsed time from the start of combustion of the burner 2 can be used as a parameter representing the temperature. Therefore, in the present embodiment, when valve opening control of the electric valve 44 is performed, as shown in FIG. 4, it is determined whether or not the elapsed time TM from the start of combustion of the burner 2 is equal to or less than a predetermined threshold YTM in STEP 41. If ≦ YTM, the process proceeds to STEP 42 and the opening operation time is made relatively short. If TM> YTM, the process goes to STEP 23 and the opening operation time is made relatively long.

  As a specific method of changing the opening operation time, there is a method of changing the moving speed (rotational speed of the motor 444) from the fully closed position to the fully open position of the valve body 443, as shown in FIG. . In this case, the gas amount changes greatly when the valve element 443 is displaced within a predetermined distance or less from the valve seat 441e. Therefore, as shown by the dotted line in FIG. 5A, the predetermined amount from the valve seat 441e (fully closed position) is obtained. It is also possible to lengthen the opening operation time by slowing the moving speed of the valve body 443 in the range below the distance.

  In the case where the motor 444 is a stepping motor, power consumption increases when the drive frequency of the motor 444 is decreased to decrease the rotation speed. Therefore, as shown in FIG. 5 (b), the valve body 443 may be intermittently moved to the closing side by intermittent operation of the motor 444, thereby extending the opening operation time. Further, it is possible to vary the opening operation time by varying the pause time of intermittent operation of the motor 444.

  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 operation time is varied by one step depending on whether or not the elapsed time from the start of combustion (temperature of the flaming portion) is equal to or greater than a threshold value. The opening operation time may be changed in several steps, or the opening operation time may be continuously changed according to the elapsed time from the start of combustion (temperature of the flame opening).

  Moreover, in the said embodiment, although the contact-type sensor contact | abutted to the bottom face of a cooking container is used as the pot bottom temperature sensor 5, you may comprise a pot bottom temperature sensor with the non-contact type sensor using infrared rays etc.

  In the above embodiment, the valve housing 441 is connected to the valve chamber 441c and the gas outlet 441b, the passage hole 441g is formed in parallel with the valve hole 441f, and the orifice 45 is provided in the passage hole 441g. The valve body 443 may be formed with a passage hole communicating the valve chamber 441c and the valve hole 441f, and an orifice may be provided in the passage hole. Such an orifice is also included in the orifice 45 in parallel with the motor-operated valve 44. .

  DESCRIPTION OF SYMBOLS 1 ... Top plate, 2 ... Burner, 3 ... Gotoku, 4 ... Gas supply path, 44 ... Electric valve, 444 ... Motor, 45 ... Orifice, 5 ... Pan bottom temperature sensor.

Claims (2)

A gas stove comprising a burner for heating a cooking vessel placed on the top plate on a top plate, and a pan bottom temperature sensor for detecting the temperature of the cooking vessel,
The gas supply path to the burner closed when the temperature detected by the pan bottom temperature sensor exceeded the upper limit temperature of the preset temperature range, and the temperature detected by the pan bottom temperature sensor fell below the lower limit temperature of the set temperature range. A motor-driven motor driven by a motor that is sometimes opened and an orifice parallel to the motor-operated valve.
The opening operation time required for switching the motor-operated valve from the closed state to the open state can be varied stepwise or continuously depending on the temperature of the flame opening so that the temperature of the flame opening of the burner becomes shorter. A gas stove characterized by Gas stove according to claim 1, characterized by using the elapsed time from the start of combustion of the burner as a parameter indicative of the temperature of the flame port portion.

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