JPH06241876A - Microwave oven weight detector - Google Patents

Abstract

(57) [Abstract] [Purpose] Weight detection of a microwave oven that automatically detects the weight of food placed on a turntable and controls the heating time of the food by microwaves based on the detected value. To provide the device at high cost by improving accuracy and sensitivity. [Structure] A weight detection body 12 is held while facing a rotation locus of a roller 3b of a turntable support body that rotates on an upper surface of a bottom plate 1a of a heating chamber 1, and the detection body 1 is provided via the bottom plate 1a.
2, a resin-made detector holder 31 integrally formed with a knob 32 for applying a pressing force from a roller is attached to the lower surface of the bottom plate 1a, and the knob 32 is moved by a repulsive force due to an elastic displacement of the knob 32 of a predetermined size. It is pressed against the lower surface of the bottom plate 1a.
Further, the detection body holder 31 is attached to the lower surface of the bottom plate 1a in a point contact relationship.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven which automatically detects the weight of food placed on a turntable and controls the heating time of the food by microwaves based on the detected value. The present invention relates to a weight detection device.

[0002]

2. Description of the Related Art Recently, a microwave oven with a weight sensor has been in widespread use, which automatically detects the weight of food placed on a turntable and controls the thawing time or the cooking time based on the detected value. . Applicants have commercialized a weight sensor using a piezoelectric element for several years, and are disclosed in Japanese Utility Model Publication No. 2-47366 and Japanese Utility Model Publication No. 3-485.
Many applications such as No. 02 have been filed.

FIGS. 3 and 4 show a basic microwave oven with a weight sensor using a piezoelectric element. In FIG.
Reference numeral 1 is a heating chamber, 2 is a turntable on which food is placed, 3 is a support of the turntable 2, has a plurality of arms 3a in a radial shape, and a roller 3b is pivotally attached to the tip thereof. Then, the support 3 is rotated by the operation of the motor 4 attached to the lower surface of the bottom plate 1a of the heating chamber 1.
The roller 3b rotates on the upper surface of the bottom plate 1a along the rotation locus 5 as shown by the alternate long and short dash line in FIG.

Incidentally, 6 is a magnetron, 7 is a waveguide, 8 is a cabinet forming the outer shell of a microwave oven, 9 is a door,
Reference numeral 10 denotes a food placed on the turntable 2. or,
WS is a weight sensor provided on the lower surface of the upper surface of the bottom plate 1a of the heating chamber 1 facing the rotation path 5, and a piezoelectric element is used as a weight detection body.

A conventional weight sensor WS is shown in FIG. In the sensor mounting plate 11 of the weight sensor WS, the opening 11a at the center of the top surface is fitted into the hole formed in the rotation path 5 on the upper surface of the bottom plate 1a of the heating chamber 1, and the periphery of the opening is the lower surface of the bottom plate 1a. Is adhered to (for example, spot welding).
20 is a detection body holder on which the piezoelectric element 12 is mounted as a weight detection body, and 21 is a pressing force of the roller 3b (food 10
Is a synthetic resin detection body cover integrally molded with a knob 21a for applying the weight of (1) to the piezoelectric element 12.

Then, the detection body holder 20 and the detection body cover 21 are fastened and fixed to the sensor mounting plate 11 together by a plurality of screws 22. Reference numeral 13 is a blind tape for closing the hole formed in the rotation path 5 of the bottom plate 1a of the heating chamber 1.

Therefore, when the turntable 2 on which the food 10 is placed rotates together with the support 3 by the operation of the motor 4 and the roller 3b pivotally attached to the arm 3a comes on the blinding tape 13, the detection body cover 21 is provided. The knob 21 a of the piezoelectric element 1 is pressed, and the pressing force of the knob 21 a is applied to the piezoelectric element 12.
2 produces an output according to the weight of the food 10 to control the thawing time or the cooking time.

[0008]

The conventional weight detecting device described above has a weight detecting sensitivity because a hole for pressing the knob 21a is formed in the turning locus 5 on the upper surface of the bottom plate 1a of the heating chamber 1. On the other hand, it requires a blinding tape 13 for closing the hole, which is disadvantageous in appearance and cost. If the blinding tape 13 has poor durability, water or juice may enter the weight detection device through the hole. There was a risk of causing quality defects.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a weight detection body facing a roller rotation locus of a turntable support which rotates the upper surface of the bottom plate of the heating chamber. And a resin detection body holder integrally molded with a knob for applying a pressing force from the roller to the detection body through the bottom plate is attached to the bottom plate bottom surface, and the repulsive force due to the elastic displacement of the knob of a predetermined size is applied. The weight detection device has a structure in which the knob is pressed against the bottom surface of the bottom plate.

According to the second aspect of the present invention, the weight detecting body is held while facing the roller rotation locus of the turntable support which rotates the upper surface of the bottom plate of the heating chamber, and the weight detecting body is attached to the detecting body via the bottom plate. A weight detecting device having a structure in which a resin-made detecting body holder integrally molded with a knob for applying a pressing force from a roller is attached to a bottom plate lower surface, and the detecting body holder is attached in a point contact relationship with the bottom plate lower surface. To do.

A piezoelectric element, a strain sensing element, or the like can be considered as the weight sensing element.

[0012]

[Function] Since there is no hole in the bottom plate of the heating chamber, there is no need for a blinding tape, which is advantageous in appearance and cost. When the blinding tape has poor durability, poor quality of the weight detecting device caused by water or juice intruding. Disappears. In addition, according to the invention of claim 1, the vertical positional relationship between the bottom plate lower surface of the heating chamber and the detection body holder, and by extension, the weight detection body (strictly speaking, the distance between the bottom plate lower surface and the weight detection body upper surface) is constant. And again
Since the knob is elastically pressed against the lower surface of the bottom plate, the bottom plate is less likely to be deformed, and the problem that excessive pressure is continuously applied to the weight detection body when not in use (no load) is unlikely to occur.

According to the second aspect of the present invention, since the bottom plate and the detection body holder are in point contact with each other, elastic deformation of the bottom plate caused by the pressing force of the roller is more than in the case where the upper surface of the side peripheral wall of the detection body holder is in full contact. Therefore, the sensitivity of weight detection is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the weight detecting device according to the present invention will be described below with reference to the drawings. The same parts as those of the conventional example will be described with the same reference numerals. In FIG. 1, reference numeral 31 denotes a resin detection body holder attached to the lower surface of the bottom plate 1a of the heating chamber 1, and the weight detection is performed by making the upper surface of the bottom plate 1a face the rotation locus of the roller 3b of the rotating turntable support. A knob 32, which holds the piezoelectric element 12 as a body and applies a pressing force from the roller 3b to the piezoelectric element 12 via the bottom plate 1a, is integrally molded.

As shown in FIG. 2, the knob 32 is integrally formed by a cantilever type arm portion 33 extending from the side peripheral wall of the detection body holder 31 toward the center, and the top surface abutting on the lower surface of the bottom plate 1a is located side by side. 3 provided on the upper surface of the peripheral wall at equal intervals (120 ° intervals)
It is higher than the apex of the hemispherical projections 34 at a certain position by a dimension A.

A notch 35 is formed in a part of the side wall of the detector holder 31, and the notch 3 is formed.
The piezoelectric element 12 is inserted from the position 5 and housed in the piezoelectric element receiving portion 36. In this stored state, the upper surface of the piezoelectric element 12 and the knob 32
The gap with the lower surface of the is set to be slightly smaller than the dimension A.

In FIG. 1, reference numeral 36 denotes a holder mounting plate for mounting the above-mentioned detector holder 31 on the lower surface of the bottom plate 1a, which is positioned at a predetermined position and fixed to the lower surface of the bottom plate 1a by spot welding. The height B of the bottom surface of the bottom plate 1a fixed to the bottom surface of the bottom plate 1a and the holder mounting surface of the holder mounting plate 36 is calculated from the mounting surface of the detector holder 31 shown in FIG. It is set to be slightly smaller than the height dimension C to the apex.

Detecting body holder 31 accommodating the piezoelectric element 12
Is attached to the holder attachment plate 36 with a plurality of screws 38, the three hemispherical projections 34 provided on the detection body holder 31 make stable point contact with the lower surface of the bottom plate 1a slightly pushed up, and the knob 32 moves to the arm. It is pressed down against the elasticity of the portion 33 and elastically pressed against the lower surface of the bottom plate 1a. Further, the lower surface of the knob 32 appropriately presses the piezoelectric element 12.

By adopting the above-mentioned mounting structure,
Since the detector holder 31 is directly attached to the lower surface of the bottom plate 1a of the heating chamber 1 while being pressed, the distance between the lower surface of the bottom plate 1a and the upper surface of the piezoelectric element is constant, and the weight detection accuracy is improved. Further, since the knob is elastically pressed against the lower surface of the bottom plate 1a, the bottom plate is less likely to be deformed by an external force, and excessive pressure due to the deformation continues to be applied to the piezoelectric element 12 when not in use (no load). Less likely to occur.

On the other hand, since the bottom plate 1a and the detection body holder 31 are in point contact with each other, the elastic deformation of the bottom plate 1a caused by the pressing force of the roller 3b causes the bottom plate 1a to be in contact with the entire upper surface of the side peripheral wall of the detection body holder 31. 1a has a degree of freedom of deformation, and the weight detection sensitivity is improved.

[0021]

As compared with the prior art, since there is no hole in the bottom plate of the heating chamber, no blinding tape is required, which is advantageous in appearance and cost, and the weight generated when the blinding tape has poor durability. The quality of the detection device is eliminated. Moreover, according to the first aspect of the invention, the distance between the lower surface of the bottom plate of the heating chamber and the upper surface of the detection body becomes constant, so that it is possible to provide a weight detection apparatus with little variation in weight detection, that is, high weight detection accuracy. According to the second aspect of the present invention, it is possible to provide a weight detecting device having a high degree of sensitivity with a degree of freedom in deformation of the bottom plate due to point contact between the bottom plate and the detection body holder.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a detection body holder according to the present invention.

FIG. 3 is a schematic cross-sectional view of a microwave oven with a weight sensor.

FIG. 4 is a diagram showing a rotation trajectory of a roller pivotally attached to a support of a turntable.

FIG. 5 is a partially cutaway sectional view of a microwave oven equipped with a conventional weight sensor.

[Explanation of symbols]

 1 Heating Chamber 1a Bottom Plate 2 Turntable 3 Support 3b Roller 12 Piezoelectric Element (Weight Detecting Body) 31 Detecting Body Holder 32 Knob 34 Hemispherical Protrusion

Claims (2)

[Claims] 1. A weight detection body is held so as to face a roller rotation locus of a turntable support that rotates the upper surface of the bottom plate of the heating chamber, and a pressing force from a roller is applied to the detection body through the bottom plate. The knob is integrally molded with a resin-made detector holder attached to the lower surface of the bottom plate, and the knob is pressed against the lower surface of the bottom plate by the repulsive force due to the elastic displacement of the knob of a predetermined size. Weight detection device for microwave oven. 2. A weight detection body is held so as to face a roller rotation locus of a turntable support body that rotates the upper surface of the bottom plate of the heating chamber, and a pressing force from a roller is applied to the detection body through the bottom plate. A weight detecting device for a microwave oven, characterized in that a detection body holder made of resin in which a knob is integrally molded is attached to the bottom surface of the bottom plate, and the detection body holder is attached in a point contact relationship with the bottom surface of the bottom plate. .