JPS6321419A - Gas cooking stove having weight sensor - Google Patents

Abstract

PURPOSE:To accurately determine the amount of foodstuff to be cooked and to detect the boiling point by providing a bridge circuit which measures the weight by means of the amount of imbalance in the circuit which comprises vessel support hooks having a weight sensing part and multiple stain gauges affixed to the front and rear surfaces thereof. CONSTITUTION:The vertical part 12b of a vessel support hook 12a is so formed that its strain due to the weight of a pot etc. is larger than other parts of the vessel support hook 12a. A strain gauge 12c has characteristics in which its resistance is increased relative to the tension strain and is decreased relative to the compression strain. A bridge circuit is formed by a total of eight identical strain gauges 12c which are affixed to the front and rear surfaces of the weight sensing part 12c of four vessel support hooks 12a. Since the weight detection value is determined not directly from the change of the strain gauge resistance but from the amount of imbalance in the bridge circuit, there is little effect of difference in the ambient temperature to the weight detection value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a gas stove with a weight sensor that is used as a gas cooking appliance on which various types of pots and the like are placed for cooking.

Conventional Technology In recent years, there has been a trend toward automation of cooking by applying electronic technology such as temperature sensors to gas stoves.

I will explain the gas stove with a temperature sensor.

FIG. 5 shows an external view of a conventional gas stove with a temperature sensor.

(1) is a stove burner, and (2) is a temperature sensor that detects the temperature at the center of the bottom of the pot. (3) is a trivet, and the top surface 2a of the head of the temperature sensor (2) normally protrudes from the top surface 3b of the trivet pawl 3a, and by placing a pot on it, the spring inside the temperature sensor (2) is released. It is compressed, and the top surface 2a of the temperature sensor head and the top surface 3b of the trivet become the same horizontal plane.

As described above, the top surface 2a of the temperature sensor head is always in contact with the bottom of the pot, the temperature at the center of the bottom of the pot is detected, and the microcomputer uses the time differential coefficient to determine the amount of the object to be heated and calculate the boiling point. It's set.

Problems to be Solved by the Invention In detection using only a temperature sensor as in the conventional example above,
Since temperature detection is very localized, it is detected whether or not there is a solid object, such as a lump of meat or a lump of potato, in the pot directly above the top surface 2a of the temperature sensor head in the center of the bottom of the pot. Since there is a large difference in the absolute value of the temperature and its time derivative, there is a large error in determining the amount of the object to be heated. In addition, the boiling point is defined as the point at which the time differential coefficient of temperature rise significantly decreases, but depending on the type of pot, this may or may not be clearly detected, and the detection of the boiling point is limited by the type of pot. be done.

In other words, because the temperature detection point is local and the temperature is measured indirectly through the bottom of the pot rather than directly on the object to be heated, there is an intersonal point where direct information cannot be obtained by macroscopic measurement of the entire object to be heated. had.

In view of the above-mentioned problems, the present invention provides a gas stove with a weight sensor that measures macro information of the entire object to be heated and does not include errors in determining the amount of the object to be heated or detecting the boiling point.

Means for Solving the Problems The gas stove with a weight sensor of the present invention has a plurality of trivet claws each having a weight detecting section that generates relatively large distortion due to the weight of the object to be heated. It is characterized by comprising a bridge circuit using resistance wire thin film strain gauges of the same performance, and comprising an electric circuit for measuring weight based on the amount of imbalance of the bridge circuit.

Effects of the present invention With the above-described configuration, if the weight of the container to be heated such as a pot is measured in advance, the amount of the object to be heated (cooked object) can be accurately measured, and a large amount of steam is generated after boiling. By utilizing the fact that the time derivative of weight significantly decreases before and after boiling, the boiling point can be accurately detected regardless of the type of pot.

EXAMPLE Hereinafter, an example of a gas stove with a weight sensor according to the present invention will be described with reference to the drawings.

Figure 1 shows an external view of one embodiment of the gas stove with a weight sensor of the present invention, where αυ is the stove burner, α2 is the trivet, [2& is the trivet stopper, and [2b is the weight detection part (
12c is a resistance wire thin film strain gauge (hereinafter referred to as a strain gauge). Gotoku Tsume 12
a consists of a horizontal portion L2d and a vertical portion 121), and horizontal portion 12(l) has a vertical cross-sectional shape as shown in FIG.
As shown in the vertical cross-sectional view of a), the width 11A is small, the height B is large, the bending stiffness and moment of inertia 21) of the cross section are large, and almost no bending strain occurs due to the weight of the pot or the like. On the other hand, the vertical portion 12b of the trivet claw L2a, which is the weight detection portion, has a horizontal cross-sectional shape as shown in the horizontal cross-sectional view of FIG. 2 (1)).
The width O is large, the height D is small, the bending stiffness (secondary moment of cross section):I) is small, and the bending strain due to the weight of the pot etc. It constitutes the overall shape of the pawl 12a.

M amount detection part of trivet claw t2a + stove burner α of 217
The surface far from υ (hereinafter referred to as the front side) produces tensile strain in response to the load of the pot, and the surface closer to the stove burner α (hereinafter referred to as the back side) produces tensile strain in response to the load of the pot. Generates compressive strain. The strain gauge L2c has a property that its resistance value increases with respect to tensile strain and decreases with respect to compressive strain. This is because the extremely thin resistor m (about lOμ) printed on the strain gauge [2o] is the elongation of the object to be detected.
This is to expand and contract following the shrinkage. 4 trivet claws
A total of 8 strain gauges with the same performance were attached to the front and back sides of the 21L weight detection unit 12b with cyanoacrylate adhesive (00-15A) [2c, shown in Figure 3 (1)]. Configure a bridge circuit like this. As shown in Figure 3 (&), if the four trivet claws are X + 7
1z and u, the circuit configuration of each strain gauge 12c is as shown in FIG. 3(1)). Connect the strain gauges on the front and back sides of the opposing trivet claws in series, and connect the strain gauges on the front and back sides of the trivet claws facing each other in series. The DC power supply voltage (Voo) is applied to the ground (G) (not only the ground but also a constant potential point different from the A contact).

For the other facing trivet claw, there are two types: one where the strain gauges on the front side are connected together, and one where the strain gauges on the back side are connected together. (In other words, which 4-disc set is front - front 1 B contact - back 1 back, then back - back 1 contact - front 1 front) so that the potentials are reversed. Connect them together and apply them to the same DC power supply voltage (voD) and ground (G).

The potential of the B contact and the potential of the D contact are connected to a differential amplifier (AMP).
) Let the output (OUT) differentially amplified by α3 be the weight detection value.

With the above circuit configuration, the front surfaces are directly connected to each other and the back surfaces are directly connected, so the output of the detected value can be increased.Since the trivets facing each other are connected, it is possible to increase the output of the detected value. Even if the weight measurement object is placed slightly off the center of the trivet, the detected value does not include a large error. In addition, all strain gauges are in the same temperature environment, and the change in resistance value of the strain gauge is not directly used as the weight detection value, but the amount of imbalance in the bridge circuit is used as the superposition detection value, so the temperature environment The difference in weight has almost no effect on the detected weight value.

When actually cooking, by measuring the weight of only the container to be heated, such as a pot, in advance and subtracting it from the total weight including the object to be heated, the accurate weight of only the object to be heated can be detected. Further, when detecting the boiling point, the weight change of the object to be heated during cooking with respect to the heating time is as shown in FIG. α−
Before boiling, almost no water vapor is generated between β and the time change (decrease) in weight is negligible; when it boils, as in the case between β and 1, significant water vapor is generated and the weight changes (decrease) over time. When the weight increases and almost no water is present, the amount of water vapor generated becomes small again, and the change in weight over time becomes small as shown after the first point.

As mentioned above, the change in weight over time (time derivative of weight)
By following , the point at which the weight decreases over time becomes large, β
It is possible to detect a point as a boiling point, a point at which the weight decreases over time again, and a point as a burning point.

The above-mentioned changes in weight over time appear similarly even when the weight of the container to be heated is included.

In this example, there were 4 trivet claws, but 6
It may be made into a book, 8 books, etc. The shape of the trivet does not have to be the same as in this embodiment, as long as it generates a relatively large bending strain at the strain gauge attachment portion. Further, in combination with the conventional gas stove with a temperature sensor, the present invention can be used as a gas stove equipped with both a temperature sensor and a weight sensor, making it possible to more accurately determine the amount of the object to be heated and detect the boiling point.

Effects of the Invention As described above, the present invention provides trivet claws having a shape that has a weight detection part that generates relatively large distortion when a container for heated objects such as a pot is placed thereon, and several trivet claws attached to the front and back of the trivet claws. By equipping the strain gauge with a bridge circuit that measures the weight based on the amount of imbalance in the circuit, it is possible to grasp macroscopic information of the entire object to be heated, and eliminate errors in determining the amount of the object to be heated and detecting the boiling point. It has the effect of eliminating the presence of

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a gas stove with a weight sensor according to an embodiment of the present invention, and FIGS. 2(a) and (b) are vertical and horizontal cross-sectional views of the horizontal and vertical portions of the trivet. Figures 3 (&) and <b) are an explanatory diagram of the arrangement of trivet claws and a diagram of the bridge circuit configuration for weight detection using strain gauges, Figure 4 is a chart showing changes in the weight of the heated object with respect to heating time, and Figure 5 The figure is an external perspective view of a conventional gas stove with a temperature sensor. 11: Stove burner 12: Trivet 12a: Trivet claw 12b: Weight detection part of trivet claw 12c: Resistance wire thin film strain gauge 12d: Horizontal part of trivet claw

Claims (1)

[Claims] A bridge circuit is constructed with resistance wire thin film strain gauges of the same performance attached to the front and back of each weight detection part of a plurality of trivets, each having a weight detection part that generates a relatively large strain due to the weight of the container to be heated. , a gas stove with a weight sensor, characterized in that it is equipped with an electric circuit that measures weight based on the amount of imbalance in the bridge circuit.