JPH05131076A - Dynamic quantity detector and washing machine utilizing thereof - Google Patents

Abstract

PURPOSE:To correctly detect the weight of a measured article independently of the deflection between the direction of the line of force of the weight of the measured article and the sensing direction of a dynamic quantity detector. CONSTITUTION:An added body 1 for placing a measured article W is supported by a spring 2 installed on a supporting body 3. Keeping a certain distance from the added body 1, a plurality of conversion elements 4 are installed on the supporting body 3. The spring 2 is deformed by the weight of the measured article W, and the deformation quantity is detected by each conversion element 4 and outputted. The true weight is obtained from the output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical quantity detector for detecting mechanical quantities such as weight and force for household appliances and industrial purposes. For example, a weight scale, an electronic scale, an on-vehicle quantity measuring machine, a load cell, etc. It can be used as any weight detector. Especially, it is effective in a situation where it is difficult to place the object to be measured on the load axis of the weight detector.

[0002]

2. Description of the Related Art As a device for detecting weight or force, it is used for consumer products such as weight scales and electronic scales for relatively small loads, and relatively large devices such as vehicle-mounted quantity measuring machines and press machines. There are industrial applications for loads, and high precision measurement represented by load cells.

These mechanical quantity detectors convert the mechanical quantity into an electric signal and output it, and it is necessary to strictly adjust the origin and set the weighing range according to the purpose. Further, the operating environment temperature also needs to be set relatively strictly, which means that the handling of each mechanical quantity detector is specialized.

As means for converting a mechanical quantity into an electric signal, one using a strain gauge, one detecting a capacitance of a parallel electrode plate, one utilizing a magnetostriction effect of a magnetic material, and a Hall element or an MR element There are various types such as those that capture the displacement of the magnet by using the.However, in most of these mechanical quantity detectors, the measured object is placed at a predetermined position and measured according to a determined method. The original function is obtained. Therefore, the balance to which the above-mentioned mechanical quantity detector is applied is the key to accuracy improvement in how accurately the weight of the measured object placed at any position on the measuring table is transmitted to the mechanical quantity detector. Become.

However, there are many cases where the mechanical quantity detector cannot be placed on the line of force of the weight of the object to be measured because of its structure. For example, a weight detector for a microwave oven is installed on a rotary shaft of a turntable, and its output varies depending on where on the turntable the cooked product is placed. In such a case, it is general to utilize the rotation of the turntable and use the integrated value or the average value of the output per time as the measured value of the weight.

Regarding the weight sensor of the laundry in the washing machine, JP-A-60-34493 and JP-B-61-445.
No. 18, Japanese Patent Laid-Open No. 61-263486 discloses that when a weight of a washing machine having four corners suspended by a suspension is to be measured, the weight is detected only at one position. Even if the device is installed, there is no problem if the center of gravity is always constant, but if the center of gravity changes depending on the loading position of the laundry, the measured value becomes completely unreliable. In such a case, it is common to install weight detectors at all four corners in order to obtain the resultant force of each component acting on each suspension.

[0007]

As described above, in order to maximize the performance of the mechanical quantity detector, it is necessary to pay attention to the force sensing direction. It must match the sensing direction. Even if the force lines are unavoidably displaced, the output value is unreliable unless there is a guarantee that the direction of force generation is always the same.

In view of the above, the present invention has an object to provide a mechanical quantity detector which can obtain a reliable output even if the direction of the force line is deviated.

[0009]

As shown in FIGS. 1 and 2, the means for solving the problems according to claim 1 of the present invention supports an additional body 1 to which a mechanical quantity such as weight and force is added, and the additional body 1. Elastic body 2
And a plurality of transducers 4 for detecting a deformation amount of the elastic body 2 due to a mechanical amount and converting the deformation amount into an electric signal.
Is arranged at a fixed position relative to the additional body 1.

In the second aspect, the outer frame 15 has a plurality of support rods 1.
In a washing machine including a water tub 16 suspended by 7, a mechanical quantity detector as a weight sensor is attached to one of the support rods 17.

[0011]

In the problem solving means according to the above-mentioned claim 1, when the transducers 4 are on the lines of force of the object to be measured W, an equal load is applied to each transducer 4, and the sum of these outputs represents the load W. ing.

When the transducer 4 is not present on the force line of the object to be measured W, the appendage 1 is inclined as shown in FIG. The forces Fa and Fb acting on the virtual force points A and B at this time satisfy the relationship of Fa + Fb = W, assuming that the additional body 1 is a rigid body.

On the other hand, the displacement amount of the virtual force points A and B is F
Since the ratio of the outputs of the transducers 4 is geometrically equal to the ratio of Fa and Fb from the figure, the sum of the outputs of the transducers 4 still depends on a and Fb. Represents.

Thus, even when the force line direction of the object to be measured W does not coincide with the sensing direction of the mechanical quantity detector, by using the plurality of transducers 4 whose relative positions are fixed to each other, It is possible to offset the change in position.

In the second aspect, when the weight sensor is attached to only one of the four rods, in the concept of the conventional mechanical quantity detector, the load applied to each rod is unique depending on the method of loading the laundry. Therefore, the sensed amount output when the laundry is not evenly put in the aquarium 16 is unreliable.

However, in the present weight sensor, the true weight can be calculated from the outputs of the plurality of conversion elements 4.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2, a mechanical quantity detector of the present embodiment includes an additional body 1 on which an object to be measured W is placed, a plurality of springs 2 for supporting the additional body 1, and each spring 2. Support 3 for supporting
And a plurality of electric converters 4 that detect the amount of deformation of the spring 2 and convert it into an electric signal.

The transducer 4 is, for example, a strain gauge or the like, and is arranged at a position spaced from the additional body 1 by a certain distance. The distance from the support body 3 by the deformation of the spring 2. Change. That is, the transmission shaft 5 fixed to the center of the additional body 1 penetrates the support body 3 and is fixed between the fixed plate 6 and the support body 3 fixed to the lower end of the support body 3, and further the transmission shaft 5 is The transducer 4 is mounted at symmetrical positions with respect to the center.

When the object to be measured W is placed right above the transmission shaft 5, the two electric transducers 4 are equally distorted.
The sum of the two represents the load W.

Next, when the measured object W is not on the transmission shaft 5, the additional body 1 is inclined as shown in FIG. The forces Fa and Fb acting on the virtual force points A and B at this time satisfy the relationship of Fa + Fb = W, assuming that the additional body 1 is a rigid body.

On the other hand, the displacement amount of the virtual force points A and B is F
It is obvious that it depends on a and Fb, and it is possible to measure the weight even if this displacement amount is converted into an electric signal. On the other hand, it is clear from the figure that the ratio of the outputs of the electric transducers 4 placed at equal distances from the object about the transmission shaft 5 is geometrically equal to the ratio of Fa and Fb. It is self-evident that the sum of the outputs of the converter 4 also represents the load W.

As described above, even when the vector of the weight of the object to be measured W does not coincide with the sensing direction of the mechanical quantity detector, the plurality of electric transducers 4 whose relative positions are fixed are used to determine the center of gravity. It is possible to offset the change in position.

Next, as shown in FIG. 3, the beam 10 having the length L is moved to the length L0 from the rotation supporting ends X and Y which are also separated by the distance L.
Consider a state in which the spring rods 11 and 12 are rotatably suspended.

Assuming that a load of weight W is placed at a distance of 1 from the right end as shown in the figure, the spring rods 11 and 12 are inclined at angles α and β, respectively, due to the shift of the center of gravity. This inclination angle is uniquely determined by the spring constant of the spring rod, the load W, and the position of the center of gravity.

Then, the respective spring rods 11 and 1
Measure the axial load of 2 and take the sum to obtain F'a + F'b
= W, the weight W of the object to be measured can be easily obtained,
This requires as many dynamic quantity detectors as there are spring rods.

Therefore, when the mechanical quantity detector according to the present invention is mounted right above the rotary support end X, the displacement amount of the spring rod is small enough to be ignored in comparison with the length of the beam and the length of the spring rod. Then, r≈0 and α = β
Is established. Only under this condition, the outputs of the plurality of transducers 4 placed at X can represent the load W.

Even when the deformation amount of the spring rod is too large to be ignored, the inclination angle α on the X side can be calculated back from the output difference between the two electric converters 4.

As described above, even if the object to be measured is installed at a position that affects the measurement error, it is possible to cancel the influence of the displacement of the center of gravity due to the arrangement of the object to be measured, and the output of the plurality of transducers 4 It is possible to provide a mechanical quantity detector that can derive a true load from

Further, even if the entire measuring system is tilted, the tilt angle can be calculated from a plurality of transducer outputs,
The effect of the installation angle can also be offset.

Here, an embodiment in which the mechanical quantity detector of the present invention is applied to a washing machine as a weight sensor will be described.

In the washing machine, as shown in FIG. 4, a washing tub 16 is suspended from an outer frame 15 by four rods 17.

A weight sensor 18 is provided for one of the four rods 17, and the sensor 18
The case 20 is attached to one corner of the outer frame 15.

As shown in FIG. 5, a compression spring 22 is fitted in the case 20, and a receiving tray 23 is fixed to the upper end of the compression spring 22. A groove is dug in a part of the tray 23, and the ring-shaped magnet 24 shown in FIG. 6 is externally fitted using the groove as a guide. The magnetizing direction of the magnet 24 is vertical as shown in FIG. .. The ring-shaped magnet 24 is detachably fixed to the tray 23 by a stop ring 25.

In the direction of the magnetic flux generated by the magnet 24, there is an element substrate 26 to which three Hall elements 25 are attached at intervals of 120 degrees, and the element substrate 26 is screwed to the bottom of the case 20.

A hole having a diameter of about 15 mm is formed at the center of the case 20 and the tray 23, and the rod 17 is penetrated therethrough. The upper end of the rod 17 is locked to the resin rod receiver 27, and the spherical convex portion of the rod receiver 27 and the spherical concave portion of the tray 23 are fitted to each other, whereby the rod 17
The load of the washing tub 16 is directly applied to the compression spring 22.

In the mechanical quantity detector shown in FIG. 1, the case 20 of this embodiment is the additional body 1, the compression spring 22 is the elastic body 2, the hall element 25 is the transducer 4, and the tray 23 is the support body. Each corresponds to 3.

In such a washing machine, the washing tub 16 and the basic drive unit are suspended by four rods 17 as shown in FIG. 5, and the weight is about 20 kg. Therefore, in the initial stage, the weight sensor has a load of about 1/4 of 5 kg.

Now, the weight sensor is one of the four rods.
It is attached only to a book, and the conventional concept of the mechanical quantity detector cannot rely on the sensed quantity that is output except when the laundry is evenly placed in the washing tub. This is because, in the conventional concept, the load applied to each rod is not uniquely determined by the method of loading laundry.

However, in the present weight sensor, the three hall elements 25 arranged on the same circumference as the ring-shaped magnet 24 at every 120 degrees are used as electric conversion elements, and the true output from each hall element is used. You can figure out the weight.

FIG. 9 shows the output characteristics of the present weight sensor, in which the horizontal axis represents time (SEC) and the vertical axis represents the output voltage (V) of the sensor. Experiment is 5kg to 25k in the washing tub
Pseudo load was applied at intervals of 5 kg up to g, and the output voltage of each hall element was recorded by artificially shaking the washing tub. Here, the artificial roll is a pseudo shift of the center of gravity.

In the figure, the thin solid lines indicate the output voltages of the three Hall elements, and the thick solid line indicates the weight sensor output calculated from the three output voltages. From a different point of view, the thin solid line is the weight sensor output based on the conventional concept, and the thick solid line is the weight sensor output based on the present invention.

Observing FIG. 7, the output voltage of each Hall element picks up a large vibration in some places. This vibrating part corresponds to when the roll is artificially given. However, it can be seen that the output of the weight sensor is suppressed to an extremely small vibration even though the output of each Hall element greatly fluctuates. In addition, the output of the weight sensor shifts in stages for each weight, which makes this weight sensor insensitive to changes in the position of the weight such as rolling, but sensitive to the weight itself. It is supported that it reacts to.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

The mechanical quantity detector of this embodiment is intended to make it possible to calculate the total resultant force vector from a part of the force component generated by the weight and structure of the object to be measured, and the electric transducer 4 As the above, a sensor using light, ultrasonic waves, electrostatic capacity or the like may be used.

Further, the elastic body 2 is not limited to a spring, and any material may be processed into an arbitrary shape depending on the property of a mechanical quantity to be sensed, and three-dimensional deformation may be allowed.

[0046]

As is apparent from the above description, according to claim 1 of the present invention, an additional body to which a mechanical amount such as weight and force is added, an elastic body supporting the additional body, and an elastic body of the elastic body. Equipped with a plurality of transducers that detect the amount of deformation due to mechanical quantity and convert it into an electrical signal, even if the force lines of the measured object do not match the sensing direction of the mechanical quantity detector, the relative position of each other is determined. By using a plurality of fixed transducers, changes in the position of the center of gravity can be offset.

According to the second aspect, by mounting the mechanical quantity detector as a weight sensor on one of the plurality of supporting rods for suspending and supporting the water tank, even when the laundry is not evenly thrown into the water tank, The true weight of the laundry can be determined.

Therefore, unlike the conventional case, it is not necessary to mount the weight sensors on all the supporting rods, and the number of parts can be reduced to provide the washing machine at low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a mechanical quantity detector of the present invention.

FIG. 2 is a schematic diagram of a mechanical quantity detector when the direction of a force line is deviated.

FIG. 3 is a view showing a beam suspended by a spring rod to which the mechanical quantity detector of the present invention is applied.

FIG. 4 is a perspective view of a washing machine using the mechanical quantity detector of the present invention as a weight sensor.

FIG. 5 is a partially cutaway front view of the weight sensor.

FIG. 6 is a plan view of the magnet of the weight sensor.

FIG. 7 is a partially cutaway front view of the magnet.

FIG. 8 is a plan view of a substrate on which Hall elements are arranged.

FIG. 9 is a diagram showing an output characteristic of a weight sensor.

[Explanation of symbols]

 1 Addition body 2 Elastic body 4 Converter 15 Outer frame 16 Washing tub 17 Support rod

Claims (2)

[Claims] 1. An addition body to which a mechanical quantity such as weight and force is added, an elastic body supporting the addition body, and a plurality of units for detecting a deformation amount of the elastic body due to the mechanical quantity and converting the electric body into an electric signal. A mechanical quantity detector, comprising: a plurality of transducers, wherein the transducers are arranged at a fixed position relative to the additional body. 2. A washing machine having a water tub suspended from an outer frame by a plurality of supporting rods, wherein one of the supporting rods is equipped with the mechanical quantity detector according to claim 1 as a weight sensor. A washing machine characterized by that.