JPS6345520A - Vibration tape load measuring instrument - Google Patents

Abstract

PURPOSE:To make variation in obtained vibration frequency proportional to a load to be measured and to take a measurement with high accuracy by increasing or decreasing the ratio of the transmission of the load to be measured to a vibration type sensor at a constant rate corresponding to an increase in the load. CONSTITUTION:When the load W is placed on a measuring pan 6, a ring spring 11 expands and horizontal links 3 and 4 slant by an angle theta, so that a movable column 2 is displaced down perpendicularly by (y) which is nearly equal to L.theta. At this time, part of the load W, i.e., force k.y proportional to the displacement (y) is absorbed by the spring rigidity of the flexible part 5 of a link mechanism and not transmitted to a tuning fork vibrator 9. One end of the vibrator 9 is held by a link spring 11 which has non-linear characteristics, so the ratio k.y/W of the force k.y absorbed by the link mechanism to the load decreases as the load W increases. Consequently, the ratio F/W of axial force F transmitted to the vibrator 9 and the load W increases and the relation between the load W and variation DELTAf in oscillation frequency is made linear.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to measuring force, weight, etc. using a vibrating force sensor whose natural frequency changes depending on the applied axial force. , relates to a vibratory force measuring device that can eliminate linear errors in measured values.

[Prior Art] Vibratory force sensors such as vibrating strings and tuning fork vibrators have a certain relationship between the applied axial force and the natural frequency, so they detect the frequency and calculate the pressure, force, etc. Can be used to measure weight, etc. However, since force and frequency do not have a linear relationship due to the nature of wood, it is difficult to put it into practical use unless the frequency is linearized by calculations using a microprocessor, etc., and the measurement equipment becomes complicated and expensive. The surface is also limited to a narrow range.

A conventional weight measurement tube that uses a tuning fork vibrator as a force sensor! ]! An example of the configuration of the measuring device is shown in FIG. 10, with fixed columns 1. Movable column 2 and mutually parallel horizontal rings 3, 4 connecting them
As a result, a parallelogram link mechanism is formed using the four flexible parts 5 as hinges, and a weighing pan 6 is mounted on the movable column 2. Furthermore, the arm 7 and the protrusion 8 extend laterally from the fixed column 1 and the movable column 2, respectively, and the upper and lower ends of the tuning fork vibrator 9 are held via flexures 10 and 10, respectively. Such a load measuring mechanism, except for the tuning fork vibrator 9 and the flexure 10, may be formed into an integral structure by machining or gui-casting, or may be constructed by assembling a suitable number of parts. When a load W to be measured is applied to the weighing pan 6, a magnitude F equal to the load W is transmitted to the tuning fork vibrator 9 as an axial force. When the tuning fork vibrator 9 is vibrated by a known method, the vibration af changes according to the axial force F,
By measuring the frequency f, the axial force F, that is, the load W can be determined.

The frequency f when the axial force F is applied is obtained by the following equation (), where fO is the frequency under no load, F is the axial force, and K is a constant determined by the tuning fork vibrator 9.

f = to・ (1+@F)” ・・・
(1) As shown in Figure 11(a), this frequency f increases when a tensile force is applied and decreases when a compressive force is applied, based on the frequency fO under no load, but in the practical example The case of a large tensile force will be mainly explained below.

FIG. 11(b) is an enlarged view of the relationship between the frequency change Af=f-To and the axial force F for the hatched portion in FIG. 11(a). As shown in (b), the actual change Δf has a linearity error ( The maximum value of the error 6 is determined by setting Δera/ΔfO to 10 as the usage range of the tuning fork vibrator 9.
If Δfra/ΔfO is set to 20%, it will reach approximately 1.2% of the 21m at full scale 2, and if Δfra/ΔfO is set to 20%, it will reach approximately 2.3%. It is extremely difficult to compensate for the linearity error (with high accuracy) using calculations other than calculations using Δrm/ΔfO.
It is practically difficult to expand this over a wide range of 10% or more.

[Objective of the Invention] An object of the present invention is to eliminate the nonlinearity that exists between the load to be measured and the obtained frequency change in a force measurement mechanism using a vibrating force sensor, and to The object of the present invention is to provide a vibratory force measuring device that gives a linear relationship to the actual value and achieves highly accurate measurements.

[Summary of the invention] The gist of the present invention is to achieve the above objects.

By using a vibrating force sensor whose frequency changes according to the applied force, and using a nonlinear spring to increase or decrease the ratio of transmitting the load to be measured to the vibrating force sensor at a constant rate as the force increases, This is a vibrating force measuring device characterized in that it is configured such that the change in the obtained vibration frequency is proportional to the force to be measured.

[Embodiments of the Invention] The present invention will be described in detail based on embodiments illustrated in FIGS. 1 to 9.

FIG. 1 is a configuration diagram of a load measuring device based on an embodiment of the present invention. There is no difference from the conventional example shown in FIG. 10, except that a ring spring 11 having nonlinear characteristics is provided in one flexure 10 portion that holds the tuning fork vibrator 9.

The operation of such a load measuring device will be explained using FIG. 2, which is based on the same principle mechanism as FIG. 1. 2nd when no load
When the load W is applied to the weighing pan 6, the ring spring 11 expands as shown in FIG. 2(b), and the horizontal link 3. 4 is the angle θ
, and the movable column 2 is vertically displaced by y×L·θ. The spring rigidity of the link mechanism is determined by the four flexible parts 5.5.
5.5, and acts as a reaction torque T against the load W. However, since the inclination angle θ and the vertical displacement y are minute, the link mechanism has a Assume that an elastic drag force of magnitude -y acts on . In this case, k is the equivalent spring coefficient of the linkage for vertical displacement y. Furthermore, as is clear from FIG. 2(b), the extension of the swing spring 11 and the displacement of the movable column 2 are the same.

When a measurement load W is applied to the conventional load measuring device shown in FIG. -y is absorbed by a force proportional to the displacement y and is not transmitted to the tuning fork vibrator 9.

However, in the load measuring device of the present invention, the displacement y is not made proportional to the measured load W, but the relative displacement y/W with respect to the load W is decreased as W increases. In other words, the ratio of -y to the load W, -y/W, which is the force absorbed by the link mechanism and not transmitted to the tuning fork vibrator 9, is made smaller as the load W increases. As a result, as the load W increases, the ratio F/W of the actually transmitted axial force F and the load W increases, and finally the relationship between the load W and the frequency change Δf is It is a straight line. In order to decrease the relative displacement y/w of the load measuring device as the load W increases, a ring spring 11 having a non-linear characteristic in which the spring coefficient increases as the tension increases is installed between the tuning fork vibrator 9 and the fixed part or It is only necessary to insert it into the transmission path of

Next, the present invention will be considered theoretically. By slightly modifying equation (1), equation (2) is obtained.

f/ro=1+Δf/fO= (1+K −F)ζ・
(2) In the present invention, the relationship between the axial force F applied to the tuning fork vibrator 9 and the measured load W is not the same or proportional as in conventional load measuring instruments, but is expressed as shown in the following equation (3). Basically, as the load W increases, the force transmission rate F/W increases.

F/W=(a/K) ・(1+(a/4)・W) ・
-(3) However, a is a constant that can be selected as appropriate for practical use.

By transforming equation (3) and substituting it into equation (2) and rearranging it, equation (6) can be obtained through equations (4) and (5) below.

1+KeF=(1+a-W/2)2...-(4)(1
+ to −F) l″J=1+a・W/2 −(5)Δf
/ro= a -W/ 2 - (8) As is clear from this equation (6), the change in frequency Δf is correctly proportional to the measuring tube Bw, so if the condition of equation (3) can be satisfied. The linear error ε becomes zero, and the object of the present invention is achieved.

The characteristics of the load measuring device of the present invention based on equation (3) are specifically shown in FIG. 3. In FIG. 3(a), the axial force F applied to the tuning fork vibrator 9 as the load W increases It shows that it increases as a quadratic curve. In FIG. 3(b), the axial force F actually transmitted to the tuning fork vibrator 9 with respect to the load W to be measured
The characteristic of the ratio F/W, that is, the equation ('3) itself is shown, and it can be seen that it increases linearly as the load W increases.

According to the present invention, the characteristic straight line of the transmissibility F/W for linearizing the relationship between the load W, the change in the number of tuning fork oscillators, and df is not limited to the one tree illustrated in FIG. 3(b). These are the three major features of If we rewrite equation (3) using equation (6) for ease of understanding and calculation, we obtain equation (7).

F/W-(a/K) @ (1◆Δf/(2-ro))-
(7) Figure 3(c) uses this equation (7), and the horizontal axis is Δf
/fO and zero point, that is, F/W at Δf=o
= a / K is 0.5 to 1.0 (7) This is an example of the F/W @ gender line, which is qualitatively the same as Figure 3 (b). , Δf/f
20% of o is set as the measurement range, and the force transmission rate F near the zero point is
/ W = a / K is selected as 80%,
It can be seen that it is sufficient to set the F/W at maximum load to 88% and take the value obtained by connecting the two with a straight line at the midpoint. -As the crotch area,
As can be easily seen from equation (7), F at the zero point
/W as the standard, 10% of Δf/FO, F/W
All you have to do is increase it by 5%.

Based on the above considerations, the force distribution within the load measuring device of the present invention is as follows: Load W = (-y to the force absorbed by the link mechanism) + (
The axial force F) is transmitted to the tuning fork vibrator.

The ring spring 11 is easy to stretch at first, but as the applied force F increases and the ring spring 11 becomes longer in the direction of the force F, as illustrated in FIG. As F becomes smaller, qualitatively speaking, as the measured load W increases, the relative displacement y/W with respect to the load W also decreases. This is shown in the F-W curve in Figure 5,
As the load W increases, the rate of increase in #y in the force absorbed by the link mechanism decreases, but on the other hand, the transmission rate F/W of the force to the tuning fork vibrator 9 increases. The FW curve in FIG. 5 corresponds to the theoretical characteristic curve in FIG. 3(a), and if they match, the linearity error ε of the embodiment becomes zero.

As a result of a modified experiment, the direct kQ error ε/Δfm of the load measuring device according to the embodiment of the present invention shown in FIG. 1 was found to be Δfra/
It has been proven that when the range of ΔfO is 10%, a high accuracy of ±0.01% is achieved, and the reduction can be reduced to less than 1/100 of the conventional mechanism.

The ring spring 11 used in the load measuring device of the present invention includes:
Oval ring spring 1 illustrated in FIGS. 1, 2, and 4
In addition to 1, those illustrated in FIGS. 6(a) to 6(g), or those having a wide variety of other shapes can be used. Simply put, it is sufficient to use a spring whose spring coefficient increases as it expands. Figure 6 (
D, (g) is essentially a composite of two types of springs, large and small, and is sometimes effective when finely pursuing linear viscosity.

FIG. 7(a) shows another embodiment in which the vibration type sensor described in Japanese Unexamined Patent Application Publication No. 10122/1983 by the present applicant is incorporated into a load measuring device. Tuning fork vibrator 9 is lever 12.
The base 13 and the tension piece 14 are integrally formed, and the base 13 is attached to the arm 7, and the lower end of the tension piece 14 is attached to the protrusion 8, respectively.

A ring spring 11 having nonlinear characteristics, which is the basis of the present invention, is provided in the middle of the tension piece 14. Regarding the functions and effects related to linearization, there is no fundamental difference from the embodiment shown in FIG. 1, so a description thereof will be omitted. Regarding the installation location of the ring spring 11, it is of course possible to provide it in connection with the tuning fork vibrator 9, similar to the embodiment shown in FIG.

- As the crotch part, the ring spring 11 may be provided either between the tuning fork vibrator 9 and the fixed part or in the force transmission path between the tuning fork vibrator 9 and the flexible part.

In the embodiment shown in FIG. 7(b), a leaf spring 11' having nonlinear characteristics is used in place of the ring spring 11 shown in FIG. 7(a). The base of the leaf spring 11° is fixed to the lever 12, and the tension piece 14 is attached to the tip, but at least one of the opposing surfaces of the lever 12 and the leaf spring 11° is curved, so that both sides are curved. The spacing increases non-linearly towards the tip. In such a leaf spring 11', as the deflection y of the tip increases, the fixed point changes, and the leaf spring 11
Since the effective length of ' becomes shorter, the spring modulus increases as the tensile force increases. This characteristic is completely similar to that of the nonlinear ring spring 11 shown in FIG. 4, and the measuring mechanism of FIG. 7(b) can also achieve the purpose of linearization in the same way as the mechanism of FIG. 7(a).

FIG. 8 shows an embodiment in which the device is not a load measuring device, but is applied to pressure measurement. A bellows 21 attached to the bottom plate 20 is configured to introduce a fluid whose pressure is to be measured through a hole 22, and a bellows is attached to a lever 25 extending from a flexible portion 24 at the top of the column 23. 21 and the upper end of the tuning fork vibrator 9 are attached, and the lower end of the tuning fork vibrator 9 is attached to the bottom plate 20 via the ring spring 11. If the measured pressure of the fluid increases, the bellows 21 and ring spring 11 will expand, and the flexible portion 24 will rotate slightly. Similar to the previous example,
Since the increase in pressure is not proportional to the elongation of the ring spring 11, the ratio of the force absorbed by the elastic resistance of the bellows 21 and the flexible portion 24 decreases as the pressure increases. On the other hand, since the tension applied to the tuning fork vibrator 9 increases more than the rate of increase in pressure, a change in frequency proportional to the measured pressure is obtained as a result.

FIG. 9 shows a principle diagram of yet another embodiment. The tuning fork vibrator 9 is attached between the end of the lever 31 on one side of the fulcrum 30 and the fixed part, and the measurement load W is attached to the lever 32 on the other side of the fulcrum 30, which is inclined at an angle θ with respect to the horizontal direction. It is added vertically downward to the end portion 33. In the middle of the lever 32 is a ring spring 34 that can be easily expanded and contracted only in the longitudinal direction of the lever 32.
is provided. In a load measuring mechanism using such a lever 32, a is the length of the lever 31 on the tuning fork vibrator side,
When b is the length of the lever 32 on the load side, the ratio between the tension F applied to the tuning fork vibrator 9 and the measuring tube gEW is given by the following equation.

F/W-(b/&) IIcosO-(8) By the way, the length b of the load side of the lever 32 is not constant, and when the load W is applied, bO is changed by the action of the component force W・sinθ in that direction. The length of lever 32 when W = 0, C is lever 32
The length b of the lever 32 expands in proportion to the load W as shown in the following equation.

b=bo* (1+c eve sinθ)
-(9) Furthermore, by summarizing equations (8) and (8), we get the following (
10) Equation is obtained.

F/W= (bO/a) a cosθ* (1
+c-W* sin θ) ・(10) This (10)
On the right side of the equation, everything except the load W is constant, so
According to the present invention, the ratio of the tension F transmitted to the tuning fork vibrator 9 to the load W increases at a constant ratio according to the increase in the load W, and the change in the frequency of the tuning fork vibrator 9 is made proportional to the load W. It appears that the purpose has been achieved.

[)A effect] As explained above, the vibrating force measuring device according to the present invention has the following effects:
It has the following advantages:

(1) By simply inserting an extremely simple nonlinear spring, such as a ring spring, between the vibrating force sensor and the fixed part or into the force transmission path, the nonlinearity of the vibrating force sensor can be virtually eliminated. Therefore, an inexpensive and highly accurate vibrating force measuring device can be obtained.

(2) Linear output force can be measured without using a microprocessor. Even if linear compensation using calculations by a microprocessor or other electronic circuit is used together, the compensation device becomes simpler and the linear accuracy after compensation is significantly improved.

(3) Due to the non-linearity of the vibrating force sensor, the frequency change range ΔfmlΔFO that can be used for measurement was previously effectively limited to about 10%, but the constraints on linearization will be relaxed. Therefore, it can be expanded by 20% or more. This means that various errors such as zero point drift, creep, hysteresis, and reproducibility become relatively small, and accuracy other than linearity also improves.

[Brief explanation of drawings]

The drawings show an embodiment of the vibrating force measuring device according to the present invention,
Figure 1 is its configuration diagram, Figure 2 is an explanatory diagram of the operation of Figure 1, Figure 3 is the basic theoretical characteristic diagram, Figure 4 is the characteristic diagram of the ring spring, and Figure 5 is the implementation of Figure 1. A graph of the relationship between load and axial force in the example, Figure 6 is a shape diagram of various nonlinear springs, Figure 7 is a configuration diagram of another embodiment, Figure 8 is a configuration diagram of a vibrating pressure measuring device,
FIG. 9 is a principle diagram of still another embodiment, FIG. 10 is a configuration diagram of a conventional vibratory load measuring device, and FIG. 11 is a characteristic diagram of a tuning fork vibrator. 1 is a fixed column, 2 is a movable column, 3.4 is a link, 5 is a flexible part, 9 is a tuning fork vibrator, 11.34 is a ring spring, 14
is a tension piece, 21 is a bellows, 25.31.32 is a lever,
30 is a fulcrum. Figure 1 Figure 2 (O) Figure 10 Figure 11 (0) (b) Axial force F Procedural amendment (voluntary) March 13, 1988 Commissioner of the Patent Office Kuro 1) Akio Tono 2, Invention Name: Vibratory load measuring device 3, relationship with 119 persons making corrections Patent applicant address: 3-9-11 Yushima, Bunkyo-ku, Tokyo Name: Shinko Denshi Co., Ltd. Representative: Yuzuru Nishiguchi 4, agent: 121 Tokyo, Japan C-104 Umejima High Town, 2-17-3 Umejima, Adachi-ku Title of the invention in the application, Description 6, and content of amendments (1) Change the name of the invention in the application from "vibrating force measuring device" to "
"Vibration load measuring device". (2) Amend the specification according to the attached amended specification. Amendment Statement 1, Name of the Invention Vibratory Load Measuring Device 2, Claim 1, Using a vibrating force sensor whose frequency changes according to the applied force, the load to be measured is measured using the vibrating force sensor. A vibrating front panel characterized in that the ratio of transmission to the force sensor is increased or decreased by a nonlinear spring at a constant rate in response to an increase in force, so that the resulting change in frequency is proportional to the cage to be measured. 1 measuring device. 2. The nonlinear spring whose spring coefficient increases or decreases as the tensile force or compressive force increases is provided between the vibrating force sensor and the fixed part or in a path that transmits the force to be added to the vibrating force sensor. , the ratio of force to the measurement load that is absorbed into the mechanism and not transmitted to the vibrating force sensor based on elastic deformation that occurs in the measurement mechanism depending on the housing to be measured is decreased as the force increases. A vibratory load measuring device according to claim 1. 3. Detailed Description of the Invention [Field of Industrial Application] The present invention is applicable to measuring force, weight, etc. using a vibrating force sensor whose natural frequency changes according to the applied axial force. , relates to a vibrating load measurement device that can eliminate linear errors in measured values. [Prior Art] Vibratory force sensors such as vibrating strings and tuning fork vibrators have a certain relationship between the applied axial force and the natural frequency, so they detect the frequency and calculate the pressure-force ratio. Can be used to measure weight, etc. However, since force and frequency do not have a linear relationship due to the nature of wood, it is difficult to put it into practical use unless the frequency is linearized by calculations using a microprocessor, etc., and the measurement equipment becomes complicated and expensive, making it difficult to apply. limited to a narrow range. Conventional ff1ffi using a tuning fork vibrator as a force sensor
An example of the configuration of the measurement load measuring device is shown in Fig. 10. Fixed column 1
, movable columns 2 and mutually parallel horizontal links 3 connecting them
．． 4 forms a parallelogram link mechanism using the four flexible parts 5 as hinges, and a weighing pan 6 is mounted on the movable column 2. Furthermore, the arm 7 and the protrusion 8 extend laterally from the fixed column 1 and the movable column 2, respectively, and the upper and lower ends of the tuning fork vibrator 9 are held via flexures 10 and 10, respectively. Such a load measuring mechanism, except for the tuning fork vibrator 9 and the flexure 10, may be formed into an integral structure by machining or gui-casting, or may be constructed by assembling a suitable number of parts. When a load W to be measured is applied to the weighing pan 6, a magnitude F equal to the load W is transmitted to the tuning fork vibrator 9 as an axial force. Tuning fork vibrator 9 by a known method
When vibrated, the frequency f changes according to the axial force F, and by measuring the frequency f, the axial force F, that is, the load W can be determined. The frequency f when the axial force F is applied is obtained by the following equation (1), where fo is the frequency under no load, F is the axial force, and K is a constant determined by the tuning fork vibrator 9. f = 10・ (1+ to −F) I ... (
1) As shown in Figure 11(a), this frequency f increases when a tensile force is applied, and decreases when a compressive force is applied, based on the frequency fO under no load, but there are many practical examples. The case of tensile force will be mainly explained below. FIG. 11(b) is an enlarged view of the relationship between the frequency change Δf=f−fo and the axial force F for the hatched portion in FIG. 11(a). As shown in (b), with respect to the straight line connecting the point of frequency change Δfm in the axial force Fm at full scale and the zero point, the actual change Δ
f has a linearity error ε. The maximum value of the error ε is approximately 1.2 with respect to ΔFrs at full scale when Δfm/fO is selected as 10% as the usage range of the tuning fork vibrator 9.
If % and ff/fo are selected to be 20%, it will reach approximately 2.3%, so as mentioned above, it is extremely difficult to compensate for the linearity error ε with high accuracy other than through calculation by a microprocessor. Even after compensation, there may be a non-negligible error, so it is practically difficult to expand Δfm/fo to a wide range of 10% or more. [Object of the Invention] An object of the present invention is to eliminate non-linearity that exists between the load to be measured and the obtained frequency change in a force measurement mechanism using a vibrating force sensor, and to eliminate the non-linearity between the two. It is an object of the present invention to provide a vibratory load measuring device that provides a substantially linear relationship and achieves highly accurate measurements. [Summary of the Invention] The gist of the present invention for achieving the above-mentioned objects is as follows. By using a vibrating force sensor whose frequency changes according to the applied force, and using a nonlinear spring to increase or decrease the ratio of transmitting the load to be measured to the vibrating force sensor at a constant rate as the force increases, This is a vibratory load measuring device characterized in that it is configured such that a change in the obtained vibration frequency is proportional to the load to be measured. [Embodiments of the Invention] The present invention will be described in detail based on embodiments illustrated in FIGS. 1 to 9. FIG. 1 is a configuration diagram of a load measuring device based on an embodiment of the present invention. There is no difference from the conventional example shown in FIG. 10, except that a ring spring 11 having nonlinear characteristics is provided in one flexure 10 portion that holds the tuning fork vibrator 9. The operation of such a load measuring device will be explained using FIG. 2, which is based on the same principle mechanism as FIG. 1. 2nd when no load
When the load W is applied to the weighing pan 6, the ring spring 1 changes as shown in Fig. 2(b).
1 is extended, the horizontal link 3.4 having a length L is tilted by an angle θ, and the movable column 2 is displaced vertically downward by y−+L·θ. The spring rigidity of the link mechanism is determined by the four flexible parts 5.5.
5.5, and acts as a reaction torque T against the load fiW. However, since the inclination angle θ and the vertical displacement y are minute, the link mechanism is limited to the vertical displacement y of the movable column 2.
It is assumed that an elastic drag force of magnitude klly acts isometrically on the . In this case, k is the equivalent spring coefficient of the linkage for vertical displacement y. Furthermore, as is clear from FIG. 2(b), the extension of the ring spring 11 and the displacement y of the movable column 2 are the same. When a measurement load W is applied to the conventional load measuring device shown in FIG. y is absorbed by a force proportional to the displacement y and is not transmitted to the tuning fork vibrator 9. However, in the load measuring device of the present invention, the displacement y is not made proportional to the measured load W, but the relative displacement y/W with respect to the load W is decreased as W increases. In other words, φy/W, which is the ratio of the force key absorbed by the link mechanism and not transmitted to the tuning fork vibrator 9 to the load W, is made smaller as the load W increases. As a result, as the load W increases, the axial force F actually transmitted to the tuning fork vibrator 9 increases.
This will increase the ratio F/W between the load and the load ff1W,
Finally, the relationship between the load W and the frequency change Af is linearized. In order to decrease the relative displacement y/w of the load measuring device as the load W increases, a ring spring 11 having a non-linear characteristic in which the spring coefficient increases as the tension increases is installed between the tuning fork vibrator 9 and the fixed part or It is only necessary to insert it into the transmission path of Next, the present invention will be considered theoretically. By slightly modifying equation (1), equation (2) is obtained. f/fo=1+Δf/FO= (1+K -F) Shi...
- (2) In the present invention, the relationship between the axial force F applied to the tuning fork vibrator 9 and the measurement load W is the same as in the conventional load measuring device.
Alternatively, the basic principle is to increase the force transmission rate F/W as the load W increases, rather than proportionally, as shown in the following equation (3). F/W=(a/K) ・(1÷(a/4)・W) ・
(3) However, a is a constant that can be selected as appropriate for practical use. By transforming the equation (3) and substituting it into the equation (2), we can obtain the equation (8) through the following equations (4) and (5). 10KIIF=(1+a・W/2)2...(4)(
1+・F)'=1+aΦW/2...(s)Δ
f / fo= a @ W/ 2
-(6) As is clear from equation (6), the change in frequency Δf is correctly proportional to the measured load W, so (
If the condition of equation 3) can be satisfied, the linear error ε becomes zero, and the object of the present invention is achieved. The characteristics of the load measuring device of the present invention based on equation (3) are specifically shown in FIG. 3. In FIG. 3(a), the axial force F applied to the tuning fork vibrator 9 as the load W increases It shows that it increases as a quadratic curve. In FIG. 3(b), the axial force F actually transmitted to the tuning fork vibrator 9 with respect to the load W to be measured
The characteristics of the ratio F/W, that is, the equation (3) itself, is shown, and it can be seen that it increases linearly as the load W increases. The characteristic straight line of the transmissibility F/W for linearizing the relationship between the load W and the change in frequency Δf of the tuning fork vibrator is shown in Figure 3(b).
Another major feature of the present invention is that it is not limited to the one example shown in FIG. To facilitate understanding and calculation (6)
If equation (3) is rewritten using equation (7), equation (7) is obtained. F/W=(a/K) ・(1+Δf/(2-ro)
)・(7) Figure 3(c) uses this equation (7) and plots Δf/fo on the horizontal axis to calculate the F/W at the zero point, that is, Δf=o.
= For the case where a/K is 0.5 to 1.0, F/
This is an example of the W characteristic line, qualitatively shown in Figure 3 (
0 that has the same content as b) For example, 2 of Af/fO
Setting 0% as the measurement range, the force transmission rate F/W near the zero point
It can be seen that if = a / K is selected as 80%, the F/W at the maximum load should be 88%, and the value obtained by connecting the two with a straight line should be taken at the midpoint. -As a crotch, (7)
As can be easily seen from the formula, if the F/W at the zero point is taken as the standard, the F/W is increased by 5% for every 10% of Δf/fo.
You can increase it by increments. Based on the above considerations, the force distribution within the load measuring device of the present invention is as follows: Load W = (-y to the force absorbed by the link mechanism) +
(Axial force F transmitted to the tuning fork vibrator). The ring spring 11 is easy to stretch at first, but as the applied force F increases and the ring spring 11 becomes longer in the direction of the force F, as illustrated in FIG. F becomes smaller. Qualitatively, as the measured load W increases, the relative displacement y/W with respect to the load W similarly decreases. This is shown in the F-W curve in Figure 5,
As the load W increases, the rate of increase of -Y in the force absorbed by the link mechanism decreases, but on the other hand, the transmission rate F/W of the force to the tuning fork vibrator 9 increases. The FW curve in FIG. 5 corresponds to the theoretical characteristic curve in FIG. 3(a), and if they match, the linearity error ε of the embodiment becomes zero. As a result of a modification experiment, the linear error (/Δfm is Δfm/fo
When the range is 10%, it reaches a high accuracy of ±0.01%,
It has been proven that the size can be reduced to less than 1/100 of the conventional mechanism. In addition to the elliptical ring springs 11 illustrated in FIGS. 1, 2, and 4, the nonlinear ring springs 11 used in the load measuring device of the present invention are illustrated in FIGS. 6(a) to 6(g). It is also possible to use a variety of other shapes. Simply put, it is sufficient to use a spring whose spring coefficient increases as it expands. Figures 6(f) and 6(g) are essentially a combination of two types of springs, large and small, and are sometimes effective when fine linear accuracy is sought. FIG. 7(a) shows another embodiment in which the vibration type sensor described in Japanese Unexamined Patent Publication No. 60-10122 by the present applicant is incorporated into a load measuring device. The tuning fork vibrator 9 is a lever 12,
The base 13 and the tension piece 14 are integrally formed, and the base 13 is attached to the arm 7, and the lower end of the tension piece 14 is attached to the protrusion 8, respectively. A ring spring 11 having nonlinear characteristics, which is the basis of the present invention, is provided in the middle of the tension piece 14. Regarding the functions and effects related to linearization, there is no fundamental difference from the embodiment shown in FIG. 1, so a description thereof will be omitted. Regarding the installation location of the ring spring 11, it is of course possible to provide it in connection with the tuning fork vibrator 9, similar to the embodiment shown in FIG. - As the crotch part, the ring spring 11 may be provided either between the tuning fork vibrator 9 and the fixed part or in the force transmission path between the tuning fork vibrator 9 and the movable part. In the embodiment shown in FIG. 7(b), a plate spring 11° having nonlinear characteristics is used in place of the ring spring 11 shown in FIG. 7(a). The base of the leaf spring 11° is fixed to the lever 12, and the tension piece 14 is attached to the tip. However, at least one of the opposing surfaces of the lever 12 and the leaf spring 11' is curved, so that both sides are curved. The spacing increases non-linearly towards the tip. In such a leaf spring 11°. As the deflection y of the tip increases, the fixed point changes and the effective length of the leaf spring 11'' becomes shorter, so the spring coefficient increases as the tensile force increases. This characteristic is completely similar to that of the nonlinear ring spring 11 shown in FIG. 4, and the measuring mechanism of FIG. 7(b) can also achieve the purpose of linearization in the same way as the mechanism of FIG. 7(a). FIG. 8 shows an embodiment in which the present invention is applied not to a load measuring device but to a pressure measuring device. A bellows 21 attached to the bottom plate 20 is configured to introduce a fluid whose pressure is to be measured through a hole 22, and a bellows is attached to a lever 25 extending from a flexible portion 24 at the top of the column 23. 21 upper end and tuning fork vibrator 9
The upper end of the tuning fork vibrator 9 is attached, and the lower end of the tuning fork vibrator 9 is attached to the bottom plate 20 via a ring spring 11. If the measured pressure of the fluid increases, the bellows 21 and ring spring 11 will expand, and the flexible portion 24 will rotate slightly. As in the previous embodiment, since the increase in pressure is not proportional to the elongation of the ring spring 11, the ratio of the force absorbed by the drag force of the bellows 21 and the flexible portion 24 to the pressure decreases as the pressure increases. do. On the other hand, since the tension applied to the tuning fork vibrator 9 increases more than the rate of increase in pressure, a change in frequency proportional to the measured pressure is obtained as a result. FIG. 9 shows a principle diagram of yet another embodiment. The tuning fork vibrator 9 is attached between the end of the lever 31 on one side of the fulcrum 30 and the fixed part, and the measurement load W is attached to the lever 32 on the other side of the fulcrum 30, which is inclined at an angle θ with respect to the horizontal direction. end 3 of
3 is added vertically downward. In the middle of lever 32,
A ring spring 34 that can be easily expanded and contracted only in the longitudinal direction of the lever 32 is provided. In a load measuring mechanism using such a lever 32, a is the length of the lever 31 on the tuning fork vibrator side, and b is
When is the length of the lever 32 on the load side, the ratio of the tension F applied to the tuning fork vibrator 9 and the measurement load W is given by the following equation. F/W= (b/a) a cosθ
・(8) By the way, the length b of the load side of the lever 32 is not constant, and when the load W is applied, the component force Wasi in that direction
Due to the action of nO, when bo is the length of the lever 32 when W=O and C is the spring coefficient of the ring spring 34 regarding the extension of the lever 32, the length b of the lever 32 is calculated by the load as shown in the following equation. It expands in proportion to W. b=bO* (1+clIW* sinθ)
−(9) Furthermore, combining equations (8) and (9), we get the following (
10) Equation is obtained. F/W= (bO/a) a cosθ++ (
1+caW* 5jnO) −・−(10) This (
10) On the right side of the equation, everything except the load W is a constant, so the ratio of the tension F transmitted to the tuning fork vibrator 9 to the load W increases at a constant ratio according to the increase in the load W, and the tuning fork vibrator It can be seen that the object of the present invention, which is to make the change in the frequency of vibration 9 proportional to the load W, has been achieved. [Effects of the Invention] As explained above, the vibratory load measuring device according to the present invention has the following advantages. (1) By simply inserting an extremely simple nonlinear spring, such as a ring spring or an arcuate spring, between the vibrating force sensor and the fixed part or into the force transmission path, the nonlinearity of the vibrating force sensor can be virtually eliminated. (2) Linear output force can be measured without using a microprocessor.If linear compensation is performed using a microprocessor or other electronic circuit Even when used together, the compensator becomes simpler and the linear accuracy after compensation is significantly improved. (3) Due to the non-linearity of the vibrating force sensor, the frequency change range ΔFm/fO that can be used for measurement is However, what was previously limited to approximately 10% can now be expanded to 20% or more as constraints on linearization are relaxed.This means that zero point drift, creep, hysteresis, reproducibility, etc. This means that various errors are relatively small, and accuracy other than linearity is also improved. 4. Brief description of the drawings The drawings show an embodiment of the vibratory load measuring device according to the present invention, and FIG. Its configuration diagram, Figure 2 is an operation explanatory diagram of Figure 1,
Figure 3 is a basic theoretical characteristic diagram, Figure 4 is a characteristic diagram of a ring spring, Figure 5 is a graph of the relationship between load and axial force in the example of Figure 1, and Figure 6 is a shape of various nonlinear springs. 7 is a block diagram of another embodiment, FIG. 8 is a block diagram of a vibrating pressure measuring device, FIG. 9 is a principle diagram of still another embodiment, and FIG. 10 is a conventional vibrating pressure measuring device. The configuration diagram of the load measuring device and FIG. 11 are characteristic diagrams of the tuning fork vibrator. 1 is a fixed column, 2 is a movable column, 3.4 is a link, 5 is a flexible part, 9 is a tuning fork vibrator, 11.34 is a ring spring, 14
is a tension piece, 21 is a bellows, 25.31.32 is a lever,
30 is a fulcrum. Procedural amendment June 19, 1988 Commissioner of the Patent Office Black 1) Akio Yu Tono 2 Name of the invention Vibrating load measuring device 3 Person making the amendment Relationship to the case Patent applicant address 3-chome Yushima, Bunkyo-ku, Tokyo No. 9-11 Name: Shinko Denshi Co., Ltd. Representative: Yuzuru Nishiguchi 4, Agent: C-104 6, Umejima High Town, 2-17-3 Umejima, Adachi-ku, Tokyo 121 Subject of amendment: Filed on March 13, 1988 Procedural amendment 7, content of amendment (1) as shown in the attached sheet. (2) Delete (1) in the content of correction column. Proceedings 1 official document (spontaneous) March 13, 1988 Commissioner of the Japan Patent Office Kuro 1) Akio Yu 1, Indication of the incident 1986 Patent Application No. 115424 2, Name of the invention Vibrating load measuring device 3, Amendment Patent applicant address: 3-9-11 Yushima, Bunkyo-ku, Tokyo Name: Shinko Denshi Co., Ltd. Representative: Yuzuru Nishiguchi 4, agent: 2-17-3 Umejima, Adachi-ku, Tokyo 121 Hightown C-104 廿03 (852)3111■ 5. Specification subject to amendment

Claims (1)

[Claims] 1. Using a vibrating force sensor whose frequency changes according to the applied force, the ratio of transmitting the load to be measured to the vibrating force sensor is set at a constant rate as the force increases. 1. A vibrating force measuring device characterized in that the vibration frequency is increased or decreased by a nonlinear spring so that a change in the obtained vibration frequency is proportional to the force to be measured. 2. Providing the non-linear spring whose spring coefficient increases or decreases as the tensile force or compressive force increases, between the vibrating force sensor and the fixed part or in a path that transmits the force to be measured to the vibrating force sensor. , the ratio of the force absorbed within the mechanism and not transmitted to the vibrating force sensor to the measurement load is reduced as the force increases, based on elastic deformation occurring within the measurement mechanism in response to the force to be measured. A vibrating force measuring device according to claim 1.