JPH0338485B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a weight detection device for a microwave oven that can detect the weight of an object to be cooked placed on a turntable. <Prior Art> A microwave oven is known that automatically detects the weight of an object to be cooked when the object is placed on a turntable placed in a heating chamber of the microwave oven. An example of a conventional weight detection device of this type will be described below with reference to FIGS. 2 to 5. As shown in FIGS. 2 and 4, a magnetron 2 is attached to the top wall of the heating chamber 1, and a turntable for placing the food A on the inner bottom of the heating chamber 1. 3 is installed. This turntable 3 has a roller arm 4 having a shape in which three arms extend radially as shown in FIG.
It is supported by being placed on support rollers 5 attached to the ends of each arm, and each support roller 5 rotates on the same trajectory while rolling on the bottom wall 6 of the heating chamber 1. Thus, the turntable 3 is configured to be able to rotate inside the heating chamber 1.
Further, as shown in FIG. 4, a motor 7 is installed on the lower surface side of the bottom wall 6 of the heating chamber and is fixed by a motor mounting member 8. A roller arm 4 is removably pivoted. On the other hand, as shown in FIGS. 3 and 5, a penetrating hole 6a is provided at an arbitrary position on the rotation trajectory of the support roller 5 in the bottom wall 6 of the heating chamber 1. A circular piezoelectric element 11 is disposed below and on the lower surface side of the bottom wall 6. This piezoelectric element 11 has a detection member 12 that protrudes upward, and the detection member 12 is installed so as to face and penetrate the hole 6a from below the bottom wall 6 and protrude upward. Furthermore, a fixed angle 13 fixed by spot welding is attached to the lower surface side of the bottom wall 6, and a fixed member 14 is attached to the fixed angle 13.
is secured with screws. This fixing member 14 has a female threaded portion formed on its inner circumferential surface, and is integrally constructed by screwing a height adjusting member 15, which has a male threaded portion formed on its outer circumferential surface, into a screw hole of the fixing member 14. There is. The height adjusting member 15 is formed with an inner circumferential stepped portion 15a, and the piezoelectric element 11 is supported from below by the inner circumferential stepped portion 15a. It is configured such that the set height of the piezoelectric element 11 can be adjusted as desired. In the above configuration, if the protrusion height of the piezoelectric element detection member 12 from the upper surface of the bottom wall 6 of the heating chamber 1 is not at a predetermined height position, the height adjustment member 15 is adjusted by rotation with respect to the fixed member 14. Then, the set height of the detection member 12 of the piezoelectric element 11 is adjusted. When the motor 7 is driven, the roller arm 4 rotates, and following this, each support roller 5 turns while rotating on the upper surface of the bottom wall 6, and the piezoelectric element detection member protruding from the bottom wall 6 follows the turning trajectory. Turn while overcoming 12. When the detection member 12 of the piezoelectric element 11 receives a load from above by each support roller 5, a voltage is generated in the piezoelectric element 11, and this voltage is detected to determine the weight of the food A placed on the turntable 3. This is to detect. With the above weight detection device, even if there are variations in the thickness of the coating on the circumference of the heating chamber or the thickness of the various structural members that form the heating chamber, the errors can be absorbed by adjusting the height adjustment member. This method can prevent variations in the output level from the piezoelectric element, but it is necessary to adjust the set height of each detection member when it is installed in the heating chamber, and the size of the heating chamber Considering its box-like shape, it was not suitable for mass production. <Object of the Invention> The present invention has been made in view of the above, and includes a piezoelectric element detection unit consisting of a piezoelectric element, a piezoelectric element detection member, a fixing member, and an adjustment member, with a metal cover that can be called a virtual bottom wall, and a metal cover that can be called a virtual bottom wall. The aim is to improve mass productivity by making it possible to adjust the set height of the detection member with a single element detection unit. <Example> Hereinafter, one example of the weight detection device of the present invention will be described based on the drawings. FIG. 1 is a vertical sectional view of the weight detection mechanism of the present invention, and the same or equivalent parts as in the conventional example are given the same reference numerals, and the explanation thereof will be omitted. The piezoelectric element 11 as a weight detection element is supported by the inner peripheral stepped portion 16a of the height adjustment member 16, and is connected to the output lead wires 17, 1.
7 is a hole 16b provided in the height adjustment member 16, 1
6c. The height adjustment member 16 is screwed onto the fixing member 18 and is integrated with the fixing member 18. Boss-shaped hole 18 in the center of the fixing member 18
A detection member knob 19 is inserted into the hole so as to be slidable up and down, and is inserted into the center of a dome-shaped metal cover 21 that is fixed to the fixing member 18 with a plurality of screws 20 (one location in the figure). It is incorporated with its tip protruding from the provided hole 21a. That is, the piezoelectric element 11, the height adjustment member 16, the fixing member 18, and the knob 1.
9. The metal cover 21 is integrated with screws 20 to form a piezoelectric detection unit 22 . A fixed angle 13 is attached to the bottom wall 6 of the heating chamber by spot welding, and the piezoelectric detection unit 22 is attached to the fixed angle 13 with a plurality of screws 23.
It is attached at one location (in the figure). There is a hole 6 in the bottom wall 6 of the heating chamber that is sufficiently larger than the tip of the knob 19.
A protrusion 21b is provided on the upper surface of the cover 21 to fit into the hole 6b, for example, by half punching in press working. Protrusion 2
The protruding height of 1b is set to be approximately equal to the thickness of the heating chamber bottom wall 6, and the bottom wall 6 and the upper surface of the projection 21b are approximately flush with each other. The roller 5 rolls on the bottom wall 6 in the direction of arrow A, rides on the protrusion 21b of the cover 21, passes over the knob 19, and presses the piezoelectric element 11, so that a signal corresponding to the weight is obtained. The bottom wall 6 and the protrusion 21b are almost flush with each other, and even if there is a slight difference in level, the difference in level is sufficiently far away from the tip of the knob 19, so that the impact exerted on the roller 5 by the difference in level is attenuated, and the roller 5 does not touch the knob 19. It has no effect once it arrives. In addition, the amount of protrusion of the knob 19 (dimension B) is important for weight measurement; if the amount of protrusion is too large, a sideways force will be applied to the knob 19, and if the knob 19 falls below the rolling plane of the roller 5, the roller The acceleration of gravity due to the fall of the roller 5 may be added, or conversely, the roller 5 may not fall at all.
There may be a case where the signal passes directly over the knob 19 and no output is obtained. In the conventional example, after assembling the weight detection mechanism in the heating chamber 1, the height adjusting member 15 is rotated and the fixing member 14 is
Since the amount of screwing in the detection member 12 was changed to adjust the amount of protrusion of the detection member 12 from the bottom wall 6 of the heating chamber 1, the adjustment work was difficult or the large box (heating chamber 1) had to be moved. However, in the device of the present invention, the weight detection mechanism is made into a small assembly called a piezoelectric detection unit, making it easy to adjust and suitable for mass production. Highly accurate adjustment is possible.
Moreover, even if a relatively large hole 6b is made in the bottom wall 6 of the heating chamber, the cover 21 can be fitted into the hole 6b, and
Since the bottom wall 6 and the cover 21 are brought into contact with each other at the C portion, leakage of high frequency radio waves from the hole 6b can be prevented. <Effects of the Invention> 1. The height of the knob protruding from the upper surface of the bottom wall of the heating chamber can be easily adjusted, making it possible to improve output accuracy. 2. The amount of knob protrusion can be accurately adjusted using a small assembly separate from the heating chamber. 3. Mass productivity is improved because adjustments and checks including the circuit of the weight detection mechanism can be performed by attaching it to a separate standard chassis without attaching it to the heating chamber. 4. The weight detection mechanism can be freely replaced, making it easier for mass production.
It is advantageous in terms of service.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of essential parts showing an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view showing the entire microwave oven,
FIG. 3 is a plan view of a main part showing the positional relationship between the rotation trajectory of the support roller and the piezoelectric element in FIG. 2, FIG. FIG. 1 is a heating chamber, 3 is a turntable, 4 is a roller arm, 5 is a support roller, 6 is a bottom wall, 6b is a hole,
11 is a piezoelectric element, 16 is a height adjustment member, 18 is a fixing member, 19 is a detection member, 21 is a cover, and 22 is a piezoelectric detection unit.

Claims (1)

[Claims] 1. The voltage generated in the piezoelectric element due to the load received from the support roller rotating on the upper surface of the bottom wall of the heating chamber while supporting the turntable is detected, thereby detecting the weight of the food to be cooked on the turntable. In the weight detection device of the microwave oven,
The heating chamber has a cover that faces a hole in the bottom wall of the heating chamber formed on the rotation locus of the support roller and forms a part of the bottom wall of the heating chamber, and that allows the detection member of the piezoelectric element to penetrate into the heating chamber. A weight detection device for a microwave oven, comprising a piezoelectric detection unit configured to freely adjust the set height of the detection member with respect to the heating chamber side surface of the cover.