JP2744778B2 - Weight detector for cooking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weight detector for a cooking device having a turntable such as a microwave oven, and more particularly to a weight for a cooking device which converts the weight of an object placed on the turntable into a capacitance and measures the capacitance. It relates to a detection device.

[0002]

2. Description of the Related Art In a recent microwave oven, when an object is placed on a turntable during cooking, weight measurement is automatically performed, and cooking is performed according to the measured weight. A weight detection device (conventional device) used for such a microwave oven will be described with reference to the drawings.

FIG. 5 is a longitudinal sectional front view showing an example of a conventional apparatus. In the figure, 10 is a heating chamber, 11 is a heating chamber 10
A turntable 12 rotatably disposed therein, 12 a support shaft of the turntable, 20 a drive unit provided below the heating chamber 10 and bearings 21, 2 for supporting the support shaft 12.
2, including a driven gear 23, a driving gear, a motor, and the like.

The weight detecting device 30 is provided below the driving section 20 and includes a fixed electrode plate 31, a movable electrode plate 32, and both electrode plates 3.
1, 32 adjustment mechanisms 33 are included. Fixed electrode plate 31
Is fixed to the weight detecting device main body 34 via an insulating plate. The movable electrode plate 32 is provided with a slight gap from the fixed electrode plate 31.

[0005] One end 35 of the movable electrode plate 32 is rotatably supported by a main body 34, and an intermediate portion receives the load of the support shaft 12 via a ball 36 provided at the lower end of the support shaft 12. . Further, the other end is formed in an L-shape, and its tip projects out of the main body 34 and includes an adjustment mechanism 3 including a spring 37.
3 and is always elastically supported by a spring 37.

The two electrode plates 31 and 32 are both made of metal and insulated from each other to form a kind of air capacitor. The adjusting mechanism 33 controls the spring constant of the spring and the gap between the two electrode plates 31 and 32. The default settings are adjusted.

When an object is placed on the turntable 11, the support shaft 12 slides downward and presses the movable electrode plate 32.
The movable electrode plate 32 rotates around the end 35 in the direction indicated by the arrow A, pulls the spring 37 of the adjustment mechanism 33, and balances the weight of the object. At this time, the size of the gap between the two electrode plates 31 and 32 changes more than when no object is placed on the turntable 11 and the capacitance changes accordingly. This capacitance change is measured by an oscillator (not shown) as a change in the oscillation frequency and the weight of the object is measured.

The mechanism for changing the distance between the fixed electrode plate and the movable electrode plate is, in addition to the mechanism described above, a mechanism for detecting a subtle gap change between fixed electrodes fixed to the outside of a platform weighing mechanism or a roberval mechanism as a change in capacitance. Used.

[0009]

However, in the former, it is very difficult to adjust the spring constant and the initial setting of the gap between the two electrodes by using the adjusting mechanism, so that much time is required for assembly and adjustment. Was. Also, in the latter using a platform weighing mechanism or a roberval mechanism, the measurement accuracy is greatly improved, but the number of components is larger than the former, which is disadvantageous in terms of cost, and it is difficult to miniaturize structurally. Was.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a low-cost and miniaturized weight detector for a cooking device.

[0011]

A weight detector for a cooking device according to the present invention captures the weight of an object placed on a turntable in a heating chamber as the amount of displacement of a support shaft of the turntable in the thrust direction. A weight detector for a heating cooker that converts the displacement amount into a capacitance change by a change in the gap size between a fixed electrode plate and a movable electrode plate disposed below the support shaft, and detects the capacitance change to detect the weight. So,
The movable electrode plate is formed in a gimbal spring shape, and its periphery is fixed to the main body, and the central portion is arranged so as to receive the load of the support shaft. The gimbal spring-shaped movable electrode plate includes a central plane portion, an outer peripheral portion, and a plurality of arm portions. The arm portion connects the central planar portion and the outer peripheral portion integrally so that the arm portion can be easily deformed under load. The second moment of area is formed sufficiently smaller than the central plane portion.

In the gimbal spring-shaped movable electrode plate which receives a load via the support shaft of the turntable, the outer peripheral portion and the central plane portion move in parallel with the load, so that the capacitance is substantially equal to the load. It changes linearly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an embodiment of a weight detecting device for a cooking device according to the present invention with reference to the drawings, a heating device for a cooking device as a premise of the weight detecting device for a cooking device according to the present invention will be described. The weight detection device will be described.

FIG. 1 is a front sectional view of a weight detector for a cooking device which is a premise of the weight detection device for a cooking device according to the present invention.
FIG. 2 is a side view for explaining a deformed state of the leaf spring under the load of FIG. The same parts as those in the prior art are denoted by the same reference numerals.

In FIG. 1, a support shaft 12 protrudes substantially at the center of the heating chamber 10, and a turntable plate 13 is provided at an upper end of the support shaft 12. The boss portion 13A of the turntable plate 13 is fitted to the support shaft 12 of the turntable with a predetermined dimension, and
B is configured to place the turntable 11 thereon.

At the lower side of the heating chamber 10, a motor mounting bracket 24, for example, spot-welded to the heating chamber 10, is fixed, and a turntable motor 25 for rotating the turntable 11 and a main body of the weight detecting device 40. 41 are attached. The turntable motor 25 includes a motor (not shown) that rotates synchronously with the power supply frequency, a reduction mechanism, and a support shaft 12 that outputs rotation reduced by the reduction mechanism and that can slide in the thrust direction. At the lower end of the support shaft 12, a conical or spherical protrusion 12A is formed. The weight detection device 40 includes a fixed electrode plate 42 and a movable electrode plate 4.
3 and is provided in the main body 41.

The fixed electrode plate 42 is fixed to an insulating plate 44 provided on the bottom of the main body 41. The movable electrode plate 43 is formed of a rectangular plate spring, and is supported by a knife edge 44A formed on both sides of the insulating plate 44 so as to protrude therefrom. , 4
3 form an air condenser. The protrusion 12A is supported at a substantially central portion of the movable electrode plate 43,
The rotating torque of the support shaft 12 is reduced, and the weight of the turntable 11 and the object is accurately adjusted by the movable electrode plate 43.
It can be said. The insulating plate 44 and the support shaft 12 are preferably formed of, for example, ceramic or the like. A lead wire 45 is electrically connected to the two electrode plates 42 and 43, and is connected to an external weight detection device (not shown). Next, the operation of the above-described weight detection device for a cooking device will be described.

When an object is placed on the turntable 11, the weight of the object and the turntable 11 is received at the center of the movable electrode plate 43 via the support shaft 12. Assuming now that the weight of the turntable 11 is W1, the weight of the object is W2, and the distance between the left and right knife edges 44A is 1, the deflection δ of the movable electrode plate 43 at a distance X from one of the knife edges 44A is expressed by the following equation. Is done.

[0019]

(Equation 1)

(Where E is the elastic modulus, I is the second moment of area, and the weight of the support shaft 12 is ignored).

[0021]

(Equation 2)

(See FIG. 2).

Due to the displacement, the capacitance between the two electrode plates 42 and 43 changes by a value corresponding to the displacement, and is converted into a weight by an external weight detection circuit and used for heating control.

According to the embodiment of the heating cooker weight detecting device which is the premise of the heating cooker weight detecting device of the present invention, the structure is simpler and the number of parts is smaller than that of the conventional device.
Small size and low cost can be realized. In this embodiment, when a load is applied, the rectangular plate spring forming the movable electrode plate 43 is deformed by the curve having the central portion as the vertex as described above because both ends are supported. Therefore, the relationship between the load and the change in capacitance becomes non-linear,
It is necessary to prepare an arithmetic circuit having a non-linear characteristic corresponding to this.

Next, an embodiment of the weight detecting device for a cooking device according to the present invention will be described. FIG. 3 is a plan view of a movable electrode plate used in the weight detecting device for a cooking device according to the present invention, and FIG. 4 is a side sectional view for explaining a deformed state of the movable electrode plate under the load shown in FIG.

In the embodiment of the heating cooker weight detecting device according to the present invention, the movable electrode plate 50 is formed in a gimbal spring shape (for example, a gimbal spring) instead of a rectangular plate spring, and the center plane portion 51 and the outer periphery are formed. It comprises a part 52 and a plurality of arm parts 53. The center plane portion 51 has an area acting as a movable electrode, and the outer peripheral portion 52 is fixed to the main body 41 via an insulating plate 54.

The arm portion 53 includes a central plane portion 51 and an outer peripheral portion 5.
2 are integrally connected, and the second moment of area is formed sufficiently smaller than that of the center plane portion 51 so that the second moment can be easily deformed under load. The arm 53
Is usually preferably 4 to 8. When a load is applied to the center portion of the movable electrode plate 50, the center plane portion 51 is closer to the rigid body than the arm portion 53 and therefore translates downward while maintaining a substantially flat surface, and the gap with the fixed electrode plate 42 changes. I do. According to this embodiment, measurement accuracy is obtained that is not inferior to that of a weight detection device using a Roberval mechanism.

[0028]

As described above, in the device of the present invention, since the movable electrode plate is formed in a gimbal spring shape, the structure can be simplified and the device can be made compact, and furthermore, the weight detecting device utilizing a roberval mechanism. The measurement accuracy is not inferior to the measurement accuracy.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a heating cooker weight detection device which is a premise of the heating cooker weight detection device of the present invention.

FIG. 2 is a side view illustrating a deformed state of a leaf spring at the time of load shown in FIG. 1;

FIG. 3 is a plan view of a movable electrode plate of the weight detecting device for a cooking device according to the present invention.

FIG. 4 is a side sectional view illustrating a deformed state of the movable electrode plate under the load of FIG. 3;

FIG. 5 is a vertical sectional front view of a conventional microwave oven weight detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heating chamber 11 Turntable 12 Support shaft 40 Weight detection device 42 Fixed electrode plate 43 Movable electrode plate 50 Movable electrode plate 51 Center plane part 52 Outer part 53 Arm part

Claims (2)

(57) [Claims] 1. A fixed electrode plate and a movable electrode, wherein the weight of an object placed on a turntable in a heating chamber is captured as the amount of displacement of the support shaft of the turntable in the thrust direction, and the amount of displacement in the thrust direction is disposed below the support shaft. It is a weight detector for a heating cooker that converts a capacitance change by a gap size change with a plate and detects a capacitance change to detect a weight, wherein the movable electrode plate is formed in a gimbal spring shape, A weight detecting device for a cooking device, wherein a periphery thereof is fixed to a main body, and a central portion is arranged so as to receive a load of a support shaft. 2. The gimbal spring-shaped movable electrode plate includes a central plane portion, an outer peripheral portion, and a plurality of arms, and the arm portion integrally connects the central planar portion and the outer peripheral portion, so that it can be easily loaded. 2. The weight detecting device for a cooking device according to claim 1, wherein a second moment of area is formed sufficiently smaller than a central plane portion so as to be deformable.