JP5680332B2 - Metering device - Google Patents

Description

  The present invention relates to a quantitative supply device, and more particularly to a quantitative supply device that supplies an object to be weighed for a predetermined target weight value.

  For example, a reservoir containing a large amount of objects to be weighed, such as a metering apparatus for handling powdery (rose-like) objects with high fluidity such as resin pellets and granulated sugar. Some have a hopper and a weighing hopper that is disposed below the reservoir hopper and receives the supply of an object to be weighed from the reservoir hopper. A load sensor such as a load cell is attached to the weighing hopper, and the weight of an object to be weighed supplied to the weighing hopper is sequentially obtained based on a weighing signal output from the load sensor. Then, when the obtained weight measurement value coincides with a predetermined supply stop weight value smaller than the target weight value, the supply of the object to be weighed from the reservoir hopper to the weighing hopper is stopped. Thereby, the quantitative supply of supplying the objects to be weighed for the target weight value is realized. Furthermore, in order to realize this constant supply with high speed and high accuracy, the supply amount of the object to be weighed per unit time may be changed stepwise.

  Specifically, in the initial stage immediately after the supply of the weighing object from the reservoir hopper to the weighing hopper is started, the weighing object is supplied with a relatively large supply amount. As a result, the time required from the start of supply of the object to be weighed to the stop of supply, that is, the supply time, can be shortened, that is, the speed of quantitative supply can be increased. Then, when a certain amount of time has elapsed from the start of supply of the object to be weighed, for example, when the above-described weight measurement value reaches a predetermined switching weight value that is smaller than the supply stop weight value, the supply amount becomes relatively small. Can be switched. Thereby, the increasing speed of the weight measurement value that increases with the passage of time decreases, and it becomes easy to obtain the timing at which the weight measurement value coincides with the supply stop weight value, that is, the timing to stop the supply of the weighing object. . Even if a slight deviation occurs in the acquisition of the timing, the supply amount of the object to be weighed is originally suppressed to be small, so that the influence (error) due to the deviation is reduced. As a result, the accuracy of the final supplied weight value of the object to be weighed with respect to the target weight value, that is, the supply accuracy, is improved, and high accuracy of quantitative supply is realized.

  Note that the supply amount of the object to be weighed per unit time is controlled by, for example, the opening of an open / close gate provided at the discharge port at the bottom of the reservoir hopper. That is, the larger the gate opening, the larger the supply amount of the object to be weighed per unit time, and the smaller the gate opening, the smaller the supply amount of the object to be weighed per unit time. When the open / close gate is closed, the supply of the objects to be weighed from the reservoir hopper to the weighing hopper is stopped. However, even if the open / close gate is closed, the object to be weighed continues to be supplied to the weighing hopper for a while after that. This is mainly due to a distance between the open / close gate and the weighing hopper, that is, a so-called drop amount. In addition, there may be a slight response delay from when the timing for closing the open / close gate arrives, that is, after the weight measurement value matches the supply stop weight value, until the open / close gate is actually closed. ,to cause. Considering these, as described above, the supply stop weight value is set to a value smaller than the target weight value.

  Thus, in the so-called gate opening control method in which the supply amount of the object to be weighed is controlled by the gate opening, when the gate opening is changed in stages, the amount of the object before and after the switching time is changed. Due to the difference in the supply amount of the weighing object, the impact load to the weighing hopper to which the object to be weighed is supplied changes. Then, the weighing system including the weighing hopper vibrates, and an approximately sinusoidal vibration component having a frequency corresponding to the natural frequency of the weighing system is generated in the weighing signal that is the output of the weighing system. This vibration component appears as an error in the weight measurement value obtained based on the measurement signal including the vibration component. Therefore, in order to obtain an accurate weight measurement, it is necessary to wait for this vibration component to sufficiently attenuate. In particular, in order to accurately obtain the supply stop timing of the object to be weighed in the final stage where the supply amount of the object to be weighed is small, that is, the small supply stage, a waiting time until the vibration component attenuates is set. In addition, it is necessary to set a longer time for the small supply stage. However, in this case, although it is possible to achieve high accuracy of the quantitative supply, the total supply time including the small supply time becomes long, which is contrary to the speeding up of the quantitative supply. In order to avoid this inconvenience, there is a conventional one disclosed in Patent Document 1, for example.

  According to this prior art, as shown in FIG. 17A, the open / close gate is opened with the time tx as a base point when tx = 0. Thereby, the supply of the object to be weighed from the reservoir hopper to the weighing hopper is started. The gate opening Gx immediately after the start of the supply of the object to be weighed takes a certain response time and becomes a relatively large constant value of Gx = G1a. Accordingly, the supply amount of the object to be weighed per unit time also becomes a relatively large value according to the gate opening G1a. In this large supply (large input) stage, as shown in FIG. 17B, the weight measurement value Wx increases at a relatively high speed (dWx / dtx) corresponding to the gate opening G1a. When the weight measurement value Wx reaches a predetermined first switching weight value W1a that is smaller than the supply stop weight value Wca (Wx ≧ W1a), at the time t1a, medium supply (medium input) is started. ) Switch to the gradual reduction step. In this gradual decrease step, the gate opening Gx is gradually decreased as the weight measurement value Wx increases with the passage of time tx, and more specifically, the following equation using the weight measurement value Wx as a variable: 1 is controlled.

<< Formula 1 >>
Gx = (G1a-G2a) · {(W2a-Wx) / (W2a-W1a)} αa + G2a

  In Equation 1, G2a is a gate opening Gx in a small supply (small input) stage described later, and the gate opening G2a in the small supply stage is smaller than the gate opening G1a in the large supply stage ( G2a <G1a). W2a is a predetermined second switching weight value, and this second switching weight value W2a is larger than the first switching weight value W1a described above and smaller than the supply stop weight value Wca ( W1a <W2a <Wca). Further, the heel index αa is an arbitrary value satisfying 0.3 ≦ αa ≦ 0.7, and the transition of the gate opening degree Gx with respect to the elapse of time tx in the gradual decrease stage varies depending on the value of the heel index αa. For example, as the value of the power index αa is smaller, the gate opening degree Gx changes so as to swell upward in a circular arc shape (convex shape) in FIG. Then, the larger the value of the heel index αa, the smaller the bulge.

  In this gradual decrease stage, the supply amount of the object to be weighed gradually decreases with the gate opening Gx that gradually decreases with the lapse of time tx, so that the increasing speed of the weight measurement value Wx also gradually decreases. When the weight measurement value Wx reaches the second switching weight value W2a (Wx ≧ W2a), the gradual reduction stage is switched to the small supply stage at the time t2a. Note that the gate opening Gx at the time point t2a at which the gradual reduction stage is switched to the small supply stage is Gx = G2a as can be seen from Equation 1.

  In the small supply stage, this constant gate opening Gx of G2a is maintained. Thereby, the supply amount of the object to be weighed becomes a relatively small constant value corresponding to the gate opening G2a, and the increasing speed of the weight measurement value Wx further decreases. Then, when the weight measurement value Wx coincides with the supply stop weight value Wca (Wx ≧ Wca), the gate opening Gx is set to Gx = 0 at the time t3a. That is, the open / close gate is closed. However, as described above, even if the open / close gate is closed, the object to be weighed continues to be supplied to the weighing hopper for a while thereafter. Along with this, the weight measurement value Wx continues to increase, and specifically increases by the drop amount Wda. Finally, the weight measurement value Wx converges to a value Wfa (≈Wpa) close to the target weight value Wpa. When this final weight value Wfa is obtained, specifically, the weight measurement value Wx at the time t4a when the predetermined stabilization waiting time Tfa has elapsed from the supply stop time t3a when the open / close gate is closed is acquired as the final weight value Wfa. Then, the object to be weighed supplied to the weighing hopper is quickly discharged from the weighing hopper. This completes a series (one time) of quantitative supply.

  As described above, in the conventional technique disclosed in Patent Document 1, a gradual reduction stage as a middle supply stage is provided between the large supply stage and the small supply stage. In this gradual reduction stage, the gate opening Gx is continuously reduced from the same opening G1a as in the large supply stage to the same opening G2a as in the small supply stage. As a result, the difference in the supply amount of the weighing object before and after the switching times t1a and t2a between the respective stages is reduced, and the generation of vibration components at the switching times t1a and t2a is suppressed (however, The initial vibration component having a relatively large amplitude generated by the drop impact force of the object to be weighed immediately after the start of supply is not suppressed regardless of whether there is a gradual decrease step). In particular, by suppressing the generation of vibration components at the time t2a when the gradual reduction stage is switched to the small supply stage, the small supply time T3a (= t3a-t2a) can be shortened, and consequently the small supply time T3a. The total supply time Twa (= T1a + T2a + T3a) including can be shortened. The short supply time T3a is shortened by, for example, bringing the second switching weight value W2a closer to the supply stop weight value Wca. In other words, the difference Wea between these W2a and Wca (= Wca−W2a) is reduced. This is realized. Further, among the large supply time T1a (= t1a-0), the gradually decreasing time T2a (= t2a-t1a) and the small supply time T3a constituting the total supply time Twa, the gradually decreasing time T2a is conventionally used. Is the longest and the short supply time T3a is the shortest (T2a> T1a> T3a) (strictly, it is set to be so).

  By the way, in the quantitative supply device including this prior art, as mentioned above, speeding up and high accuracy of quantitative supply are regarded as important, but in addition to this, the number of executions per unit time of the quantitative supply is uniform ( (Constant), that is, equalization of the total supply time Twa may be emphasized. This requirement is particularly strong in a system in which a weight sorting device is provided at the subsequent stage of the quantitative supply device. In other words, in the system, the objects to be weighed quantitatively supplied by the quantitative supply device are sequentially sent to the subsequent weight selection device. In the weight sorting apparatus, the weights of the objects to be weighed in sequentially from the fixed quantity supply apparatus are measured with higher accuracy, and the objects to be weighed are sequentially sorted based on the measurement results. Here, the sorting accuracy (weight measurement accuracy) by the weight sorting device is higher as the time taken for the sorting process is longer. The higher the sorting accuracy, the higher the quality of the finally produced product, particularly the weight quality. On the other hand, if the time required for the sorting process is long, the production speed of the product is reduced correspondingly, that is, the productivity is lowered. Therefore, in order to satisfy the two levels of the contradictory relationship between the quality and productivity of these products at the highest possible level, the feeding time interval of the objects to be weighed sequentially fed from the quantitative feeding device to the weight sorting device ( (Period) is uniform, that is, the total supply time Twa for each quantitative supply by the quantitative supply device is required to be uniform.

  However, in the above-described conventional technology, the total supply time Twa cannot be made uniform. That is, in the related art, during the operation, the accommodation amount, the accommodation posture, and the like of the object to be weighed in the reservoir hopper change. In addition, depending on the type of the object to be weighed, properties such as its particle size, viscosity, and apparent specific gravity change during the operation. And if these various conditions change, even if it is the same gate opening degree Gx, the supply amount per unit time of a to-be-measured object will change. That is, the relationship between the gate opening Gx and the supply amount of the object to be weighed per unit time changes, in other words, the relationship between the gate opening Gx and the increase rate of the weight measurement value Wx changes. This phenomenon occurs not only in the prior art but also in other quantitative supply devices. However, in the prior art, since the switching between the respective stages is performed using the weight measurement value Wx as a control parameter, the total supply time Twa for each quantitative supply varies, and particularly occupies most of the total supply time Twa. The large supply time T1a and the gradual decrease time T2a vary significantly. Thus, in the prior art, since the total supply time Twa is not uniform, both the quality and productivity of the product are not sufficiently satisfied particularly in the system in which the weight sorting device is provided in the subsequent stage as described above.

  Thus, as another conventional technique, for example, there is one disclosed in Patent Document 2. In other words, according to the second prior art, unlike the first prior art disclosed in Patent Document 1, switching between each stage is not performed using the weight measurement value Wx as a control parameter. Switching between the stages is performed using the elapsed time tx starting from the supply start time (tx = 0) as a control parameter. That is, in the first prior art, constant weight values of the first switching weight value W1a and the second switching weight value W2a are set in advance as a comparison target standard with the weight measurement value Wx that is the control parameter. 2 In the prior art, as a reference to be compared with the elapsed time tx that is a control parameter, as shown in FIG. 18, certain time points of a first switching time point t1b and a second switching time point t2b are set in advance. Further, the elapsed time tx is measured simultaneously with the start of supply of the object to be weighed.

  Specifically, the large supply stage is set until the elapsed time tx reaches the first switching time t1b. In this large supply stage, as shown in FIG. 18A, the gate opening degree Gx is set to a relatively large constant value of Gx = G1b. Accordingly, as shown in FIG. 18B, the weight measurement value Wx increases at a relatively high speed according to the gate opening degree G1b. Then, when the elapsed time tx reaches the first switching time t1b, the large supply stage is switched to the gradual reduction stage. In this gradual reduction stage, the gate opening degree Gx is controlled based on the following equation 2 using the elapsed time tx as a variable.

<< Formula 2 >>
Gx = (G1b−G2b) · {(t2b−tx) / ( ^t2b −t1b)} ^αb + G2b

  In Equation 2, G2b is the gate opening degree Gx in the small supply stage. The gate opening G2b in the small supply stage is smaller than the gate opening G1b in the large supply stage (G2b <G1b). The heel index αb is an arbitrary value satisfying 0 <αb ≦ 1, and the transition of the gate opening degree Gx with respect to the elapsed time tx in the gradual reduction stage varies depending on the value of the heel index αb. For example, as the value of the power index αb is smaller, the gate opening degree Gx changes so as to swell upward in an arc shape in FIG. The larger the value of the power index αb is, the smaller the bulge is. When αb = 1, the gate opening degree Gx changes linearly.

  This gradual decrease step is continued until the elapsed time tx reaches the second switching time t2b, and during this time, the increase rate of the weight measurement value Wx also decreases gradually with the gate opening Gx gradually decreasing with the elapsed time tx. To do. Then, when the elapsed time tx reaches the second switching time t2b, the gradual decrease stage is switched to the small supply stage. Note that the gate opening Gx at the second switching time point t2b is Gx = G2b as can be seen from Equation 2.

  In the small supply stage, the constant gate opening Gx of G2b is maintained, and accordingly, the supply amount of the object to be weighed becomes a relatively small constant value corresponding to the gate opening G2b. Together, the weight measurement Wx increases at a lower constant rate. When the weight measurement value Wx matches the supply stop weight value Wcb (Wx ≧ Wcb), the gate opening Gx is set to Gx = 0 at the time t3b, and the open / close gate is closed. As a result, the weight measurement value Wx increases by the drop amount Wdb from the supply stop time t3b, and finally converges to a value Wfb (≈Wpb) close to the target weight value Wpb. Then, the weight measurement value Wx at the time point t4b when the predetermined stabilization waiting time Tfb has elapsed from the supply stop time point t3b is acquired as the final weight value Wfb, and then the object to be weighed in the weighing hopper is quickly discharged, and a series of The fixed amount supply ends.

  As described above, in the second prior art, as in the first prior art, a gradual reduction stage is provided between the large supply stage and the small supply stage, and therefore, the coverage before and after the switching times t1b and t2b between these stages is increased. The difference in the supply amount of the weighing object is reduced, and the generation of the vibration component at the switching times t1b and t2b is suppressed (however, the generation of the initial vibration component immediately after the start of the supply of the measurement object is not suppressed). In particular, by suppressing the generation of vibration components at the time t2b when the gradual reduction stage is switched to the small supply stage, the small supply time T3b (= t3b−t2b) can be shortened, and consequently the total supply time Twb ( = T1b + T2b + T3b) can be shortened. The shortening of the small supply time T3b is such that the expected weight measurement value W2b expected at the second switching time t2b approaches the supply stop weight value Wcb, in other words, the difference Web between the two W2b and Wcb. This is realized by setting the second switching time t2b so that (= Wcb−W2b) is reduced. Further, among the large supply time T1b (= t1b-0), the gradual decrease time T2b (= t2b-t1b) and the small supply time T3b constituting the total supply time Twb, the gradual decrease time T2b is usually the longest and small. The supply time T3b is the shortest (T2b> T1b> T3b) (strictly, it is set to be so).

  Further, according to the second prior art, the switching times t1b and t2b between the stages are constant, that is, the large supply time T1b and the gradual decrease time T2b occupying most of the total supply time Twb are constant. Therefore, only the remaining small supply time T3b becomes a variation factor of the total supply time Twb. Therefore, according to the second prior art, it seems that the fluctuation of the total supply time Twb is suppressed as compared with the first prior art, that is, the total supply time Twb is made uniform. However, even with the second prior art, it is insufficient to make the total supply time Twb uniform.

  That is, in the second prior art, switching between the respective stages is performed using the elapsed time tx as a control parameter as described above. This is because the relationship between the gate opening Gx and the supply amount per unit time of the object to be weighed. It is assumed that it is always constant, in other words, that the relationship between the gate opening Gx and the rate of increase of the weight measurement value Wx is always constant. However, this relationship varies depending on various conditions such as the properties of the object to be weighed, and as a result, the total supply time Twb varies.

  For example, it is assumed that various conditions such as the properties of the object to be weighed are stable and the relationship between the gate opening Gx and the supply amount of the object to be weighed is as expected. In this case, as indicated by a thick solid line B in FIG. 19B, which is a partially enlarged view of FIG. 18, at the second switching time t2b, the weight measurement value Wx is an expected value at the second switching time t2b. Reach W2b (Wx = W2b). Then, the weight measurement value Wx increases at a constant speed according to the gate opening G2b in the small supply stage, and at time t3b when the weight measurement value Wx coincides with the supply stop weight value Wcb, the weight measurement value Wx is thick in FIG. As indicated by the solid line A, the gate opening degree Gx is set to Gx = 0. At the intended supply stop time t3b, the vibration component generated at the second switching time t2b is sufficiently attenuated. In other words, the small supply time T3b is set so as to be, in other words, Since the weight value difference Web is set, the expected supply accuracy can be obtained as a result.

  Here, it is assumed that the relationship between the gate opening degree Gx and the supply amount of the object to be measured changes, for example, that the supply amount of the object to be weighed becomes larger than expected. In this case, as indicated by a one-dot chain line B 'in FIG. 19B, the weight measurement value Wx at the second switching time t2b is larger than the initial value W2b. That is, the difference Web ′ between the actual weight measurement value Wx and the supply stop weight value Wcb at the second switching time t2b is smaller than the initial value Web (Web ′ <Web). On the other hand, when the actual weight measurement value Wx coincides with the supply stop weight value Wcb, at time t3b ′, the gate opening degree Gx becomes Gx = 0 as shown by a one-dot chain line A ′ in FIG. It is said. In short, the gate opening degree Gx becomes Gx = 0 at a certain time point t3b ′ before the intended supply stop time point t3b. As a result, the actual small supply time T3b ′ (= t3b′−t2b) is shorter than the intended small supply time T3b (T3b ′ <T3b), and accordingly, the actual total supply time Twb ′ (= T1b + T2b + T3b). ') Is also shorter than the desired total supply time Twb (Twb' <Twb). In addition, if the actual small supply time T3b ′ is short, particularly too short, the vibration component generated at the second switching time t2b, which is also the starting point of the actual small supply time T3b ′, is not sufficiently attenuated. The supply stop time t3b ′, which is the end point of the actual small supply time T3b ′, arrives, and the supply accuracy decreases. In order to avoid this, the intended small supply time T3b may be increased by, for example, increasing the second switching time t2b or decreasing the gate opening G2b in the small supply stage. Even if it does so, the fluctuation | variation of the total supply time Twb including the said small supply time T3b cannot be suppressed. In addition, if the small supply time T3b is increased, the total supply time Twb is naturally increased, which is against the speeding up of the quantitative supply.

  On the other hand, when the supply amount of the object to be weighed becomes smaller than the expected amount, the weight measurement value Wx at the second switching time t2b becomes the expected value as shown by a two-dot chain line B ″ in FIG. That is, the difference Web ″ between the actual weight measurement value Wx and the supply stop weight value Wcb at the second switching time t2b is larger than the initial value Web (Web ″> Web). At the time point t3b ″ when the weight measurement value Wx coincides with the supply stop weight value Wcb, the gate opening Gx becomes Gx = 0 as indicated by a two-dot chain line A ″ in FIG. 19A. At a certain time t3b ″ after the supply stop time t3b, the gate opening degree Gx becomes Gx = 0. As a result, the actual small supply time T3b ″ (= t3b ″ −t2b) becomes longer than the intended small supply time T3b (T3b ″> T3b), and accordingly, the actual total supply time Twb ″ (= T1b + T2b + T3b). ") Also becomes longer than the desired total supply time Twb (Twb"> Twb).

  Thus, also in the second prior art, the total supply time Twb varies depending on various conditions such as the properties of the object to be weighed. That is, the number of executions per unit time of the constant supply cannot be made uniform.

JP-A-62-230527 Japanese Utility Model Publication No. 2-99324

  That is, the problem to be solved by the present invention is that neither the first prior art nor the second prior art described above can achieve the uniform number of executions per unit time of quantitative supply.

  Therefore, the present invention can achieve a uniform number of executions per unit time of quantitative supply in a quantitative supply apparatus that supplies an object to be measured divided into a plurality of stages including a gradual reduction stage and a small supply stage. The object is to provide a new technology that can be used.

  In order to achieve this object, the present invention provides, in a quantitative supply device for supplying an object to be weighed for a predetermined target weight value, a supply means for supplying an object to be weighed according to a supply control signal, and the supply control A supply control means for generating a signal; an elapsed time measuring means for measuring an elapsed time from a supply start time of the object to be weighed by the supplying means; Are provided. Here, the supply stop weight value smaller than the target weight value, the target switching weight value smaller than the supply stop weight value, and the elapsed time when the weight measurement value by the weight measuring means coincides with the target switching weight value. The reference switching time, which is the reference of, is determined in advance. The supply control means includes a gradual reduction stage in which the supply amount of the object to be weighed by the supply means gradually decreases, and a final stage following this gradual decrease stage, and the supply amount of the object to be weighed per unit time Is divided into a plurality of stages including a small supply stage having a constant value substantially equivalent to that at the end point of the gradual reduction stage, and a supply control signal is generated so that the object to be weighed is supplied by the supply means. Further, the supply control means switches from the gradually decreasing stage to the small supply stage at the first time point when the elapsed time measured by the elapsed time measuring means coincides with the reference switching time in the gradually decreasing stage, and at this first time point. The supply control signal is generated so that the measured weight value of the current matches the target switching weight value. In addition, the supply control means generates a supply control signal so that the supply of the object to be weighed by the supply means is stopped at the second time point when the weight measurement value matches the supply stop weight value in the small supply stage. That's it.

  That is, according to the present invention, the supply means supplies the objects to be weighed according to the supply control signal given from the supply control means. Specifically, the supply means is a gradual reduction stage in which the supply amount per unit time of the object to be weighed is gradually reduced, and a final stage following the gradual reduction stage, where the supply quantity per unit time is at the end of the gradual reduction stage. The object to be weighed is supplied in a plurality of stages including a small supply stage that is a constant value substantially equivalent to. In parallel with the supply operation of the object to be weighed by the supply means, the elapsed time measuring means measures the elapsed time from the supply start time of the object to be weighed by the supply means. In addition, the weight measuring unit measures the weight of the object to be weighed that has been supplied by the supplying unit. In addition, in the gradual reduction stage, the elapsed time measured by the elapsed time measuring means, that is, the elapsed time from the supply start time of the object to be weighed, is the first time point that matches the predetermined reference switching time. Switch from the gradual reduction stage to the small supply stage. In addition, the supply amount of the object to be weighed per unit time in the gradual reduction stage is controlled so that the weight measurement value at the first time point matches the predetermined target switching weight value. Then, in the small supply stage, the supply operation of the object to be weighed by the supply means is stopped at the second time point when the weight measurement value matches the predetermined supply stop weight value. Thereby, the quantitative supply of supplying the objects to be weighed for the target weight value is realized.

  Here, the sum of the so-called first time from the supply start time of the weighing object to the first time point and the second time from the first time point to the second time point, that is, the small supply time, is the sum of the weighing object. This is the total supply time for supply. Of this total supply time, the first time is always constant. On the other hand, the small supply time may vary depending on various conditions such as the properties of the object to be weighed. Specifically, the small supply time is determined by the weight measurement value at the first time point and the supply amount per unit time of the object to be weighed in the small supply stage. Then, the weight measurement value at the first time point of the former is constant. On the other hand, the supply amount in the latter small supply stage may change depending on various conditions such as the properties of the object to be weighed. However, the supply amount in the small supply stage is a constant value substantially equivalent to that at the end point of the gradual reduction stage, and is originally small. Therefore, even if various conditions such as the properties of the object to be weighed change and the supply amount in the small supply stage changes accordingly, the amount of fluctuation in the small supply time due to this change is extremely small. Thus, the small supply time is generally constant and the total supply time is also generally constant.

  In the present invention, the following configuration may be employed. That is, a plurality of standard weight values smaller than the switching weight value and a plurality of reference times that are references for the elapsed time when the weight measurement value matches each of the plurality of standard weight values are determined in advance. Then, the supply control means controls the supply control so that the weight measurement value at the third time point when the elapsed time coincides with each of the plurality of reference times coincides with the corresponding standard weight value in the gradual decrease stage. Generate a signal. According to this configuration, in the gradual reduction step, the actual weight measurement value at the third time point and the actual weight measurement value at the third time point when the elapsed time from the supply start time of the weighing object matches each of the plurality of reference times. The standard weight value corresponding to is compared. Then, the supply amount per unit time of the object to be weighed is controlled so that these two values coincide with each other, that is, the weight measurement value changes as expected. As a result, the weight measurement value at the first time point when the gradual decrease stage is switched to the small supply stage smoothly matches the target switching weight value.

  More specifically, the supply control unit may include a comparison unit that compares the weight measurement value at each third time point with the corresponding standard weight value. In this case, the supply control means further includes supply control signal generation means for generating a supply control signal based on the comparison result by the comparison means.

  Further, in the present invention, the first time described above from the supply start time of the weighing object to the first time point is longer than the small supply time as the second time from the first time point to the second time point, desirable. That is, among the first time and the small supply time constituting the total supply time, the first time is always constant, and the small supply time may vary although it is very small. Therefore, in order to make the total supply time uniform, it is desirable that the first time is longer than the small supply time.

  As described above, according to the present invention, in a quantitative supply device that supplies an object to be weighed in a plurality of stages including a gradual reduction stage and a small supply stage, various conditions such as the properties of the object to be weighed have changed. However, the total supply time is generally constant. That is, the number of executions per unit time of the constant supply can be made uniform. This is extremely effective in satisfying both product quality and productivity, particularly in a system in which the above-described weight sorting apparatus is provided at the subsequent stage of the quantitative supply apparatus.

It is the schematic which shows the whole structure of one Embodiment of this invention. It is a block diagram which shows the electrical structure of the control apparatus in the embodiment. It is an illustration figure which shows transition of the gate opening degree and the weight measured value with respect to progress of time at the time of the driving | running operation in the embodiment. It is an illustration figure showing transition of the gate opening degree and the weight measurement value with respect to passage of time at the time of the first test operation in the same embodiment. It is an illustration figure for demonstrating the calculation point of the weight estimated value for the improvement of the said 1st test driving | operation. It is another illustration figure for demonstrating the calculation point of the same weight estimated value. It is an illustration figure which shows transition of the gate opening degree, the weight measured value, and the weight estimated value with respect to passage of time at the time of the first test operation to which the weight estimated value is applied. It is an illustration figure showing transition of the gate opening degree, the weight measurement value, and the weight estimated value with the passage of time at the time of the second test operation in the embodiment. It is an illustration figure which shows the reference | standard table conceptually in the same embodiment. It is a flowchart which shows the flow of the automatic driving | running | working task performed by CPU in the same embodiment. It is a flowchart following FIG. 12 is a flowchart following FIG. 10 and FIG. 11. It is a flowchart which shows the flow of the interruption task performed by the CPU. It is a flowchart following FIG. It is an illustration figure for demonstrating another example in the same embodiment. FIG. 16 is an illustrative view for explaining another example different from FIG. 15. It is an illustration figure which shows transition of the gate opening degree and weight measurement value with respect to passage of time in 1st prior art. It is an illustration figure which shows transition of the gate opening degree and weight measurement value with respect to passage of time in 2nd prior art. It is an illustration figure which expands and shows a part of FIG.

  An embodiment of the present invention will be described with reference to FIGS.

  The fixed-quantity supply apparatus 10 which concerns on this embodiment handles the powdery to-be-measured object 100 with high fluidity like a resin pellet or granulated sugar, and as shown in FIG. A reservoir hopper 12 accommodated in the reservoir hopper 12, and a weighing hopper 14 which is disposed below the reservoir hopper 12 and receives the supply of the object 100 from the reservoir hopper 12. An opening / closing gate 16 is provided at the discharge port at the bottom of the reservoir hopper 12, and an opening Gx of the opening / closing gate 16 causes the weighing object 100 to be weighed from the reservoir hopper 12 to the weighing hopper 14 per unit time. The supply amount (flow rate) Qx is controlled. Note that the gate opening Gx and the supply amount Qx are the properties of the object to be weighed 100 such as the particle size, viscosity, apparent specific gravity, etc. Assuming that various situations such as postures are constant, they are correlated with each other, for example, in a proportional relationship. That is, the supply amount Qx can be considered as a mass flow rate per unit time of the object 100 to be weighed. And so that this relationship is maintained, the reservoir hopper 12 has a volume sufficiently larger than the weighing hopper 14. At the same time, the weighing object 100 is appropriately refilled in the reservoir hopper 12 by a filling device (not shown) so that the accommodation height H of the weighing object 100 in the reservoir hopper 12 is always kept within a certain range. .

  The weighing hopper 14 includes a load cell 18 as a load sensor, and the load cell 18 generates an analog load detection signal Wy having a magnitude (voltage value) corresponding to a load applied to itself. The analog load detection signal Wy is input to a control device 22 including, for example, a liquid crystal display 20 as information output means. As the load cell 18, for example, a strain gauge type is suitable, but other than this, an appropriate type such as a magnetostrictive type, a capacitance type, or a gyro type may be employed. A load sensor other than the load cell 18 may be employed.

  As shown in FIG. 2, the control device 22 includes an amplifier circuit 24, and the analog load detection signal Wy is input to the amplifier circuit 24. The analog load detection signal Wy input to the amplifier circuit 24 is amplified here and then input to the A / D conversion circuit 26. Although not shown, the amplifier circuit 24 includes a noise component in a relatively high frequency band included in the analog load detection signal Wy, specifically, a so-called line noise having a frequency of 50 Hz to 60 Hz, which is included in the analog load detection signal Wy. A low-pass filter circuit (for example, a first-order lag filter circuit) for removing noise components due to electrical factors in the above frequency band is provided. Further, the low-pass filter circuit may be incorporated in the amplifier circuit 24 itself.

  The A / D conversion circuit 26 samples the analog load detection signal Wy input via the amplifier circuit 24 in accordance with the rising edge (or falling edge) of the clock pulse CLK supplied from the clock pulse generation circuit 28 as the pulse generation means. To do. Thereby, the analog load detection signal Wy is converted into a digital signal. Note that the sampling period by the A / D conversion circuit 26, that is, the period ΔT of the clock pulse CLK is, for example, ΔT = 1 ms.

A digital load detection signal Wy after conversion by the A / D conversion circuit 26 is sent to a CPU (Central
Strictly speaking, the data is taken into the CPU 32 in accordance with the rise (or fall) of the clock pulse CLK described above. Therefore, the clock pulse CLK is also given to the CPU 32 via the input / output interface circuit 30. On the digital load detection signal Wy captured by the CPU 32, an approximately sinusoidal vibration component having a frequency corresponding to the natural frequency of the weighing system including the weighing hopper 14 is superimposed. The CPU 32 performs a first smoothing process on the digital load detection signal Wy so as to attenuate the vibration component. As the first smoothing process, the natural frequency of the balance system is approximately 10 Hz, and the natural frequency corresponds to the increase in the weight of the balance system including the object 100 when the quantitative supply described later is added. Therefore, for example, a filtering process for forming a relatively large attenuation band having a width of several Hz in the vicinity of 10 Hz, more specifically, an attenuation band by two notch frequencies of 9 Hz and 11 Hz that are close to each other is formed. Multiple (double) moving average processing is appropriate. Then, the CPU 32, based on the digital load detection signal Wy after the first smoothing process is performed, the weight value of the object to be weighed 100 currently supplied to the weighing hopper 14, that is, true supply has been completed. The weight value Wx ′ is obtained, and specifically, the weight measurement value Wx that is a measurement value of the true supplied weight value Wx ′ is obtained. Further, the CPU 32 generates a gate control signal Sg based on the weight measurement value Wx. The gate control signal Sg is input to the D / A conversion circuit 34 via the input / output interface circuit 30 and is converted into an analog signal here, and then described later for driving the open / close gate 16 described above. Input to the servo amplifier circuit 36. In addition to the gate control signal Sg, the CPU 32 generates a discharge control signal Sc. The discharge control signal Sc is given to a cylinder 38 to be described later via the input / output interface circuit 30.

  The operation of the CPU 32 is controlled by a control program stored in a memory circuit 40 serving as storage means connected to the CPU 32. Further, the display 20 described above and, for example, operation keys 42 as command input means for inputting various commands to the CPU 32 are connected to the CPU 32 via the input / output interface circuit 30. The display 20 and the operation keys 42 may be integrated with each other, and may be configured by, for example, a touch screen.

  Returning to FIG. 1, the servo amplifier circuit 36 generates a drive signal Sd for driving the servo motor 44 based on the gate control signal Sg input from the control device 22. The servo motor 44 is driven in accordance with the drive signal Sd, and the driving force is given to the open / close gate 16 via a gear mechanism 50 as a driving force transmitting means having a driving gear 46 and a driven gear 48. Thereby, the open / close gate 16 opens and closes, that is, the gate opening degree Gx is controlled. Further, the rotary shaft of the servo motor 44 is coupled with a rotary potentiometer 52 as a rotation angle detecting means for detecting the rotation angle, and the rotation angle detection signal Sp output from the potentiometer 52 is Feedback is provided to the servo amplifier circuit 36. The servo amplifier circuit 36 compares the feedback rotation angle detection signal Sp with the gate control signal Sg described above, and based on the comparison result, the desired gate opening Gx is obtained. The drive signal Sd is corrected.

  The bottom of the weighing hopper 14 forms a discharge port for discharging the object to be weighed 100 supplied to the weighing hopper 14, and this discharge port has a gate different from the open / close gate 16, so to speak. A discharge gate 54 is provided. The cylinder 38 described above is provided as a driving means for driving the discharge gate 54. As the cylinder 38, for example, a pneumatic type is suitable, but a cylinder other than the pneumatic type such as a hydraulic type can also be used. Further, instead of the cylinder 38, other drive means such as an electromagnetic solenoid or a motor may be employed.

  According to the quantitative supply device 10 according to the present embodiment configured as described above, the quantitative supply of the workpiece 100 is realized by the following procedure.

That is, also in the quantitative supply device 10 according to the present embodiment, as shown in FIG. 3, as in the first and second prior arts, as shown in FIG. The object to be weighed 100 is supplied from the reservoir hopper 12 to the weighing hopper 14 in three stages. In the small supply stage, when the weight measurement value Wx coincides with a predetermined supply stop weight value Wc that is smaller than the target weight value Wp by the head amount Wd (Wx = Wc), the supply of the object to be weighed 100 is performed. In detail, the gate opening degree Gx is set to Gx = 0. The switching from the large supply stage to the gradual reduction stage, and the switching from the gradual reduction stage to the small supply stage, as in the second prior art, are based on the starting point of supply of the object 100 (tx = 0). Time tx is used as a control parameter. For this reason, the measurement of the elapsed time tx is started at the same time as the supply of the object to be weighed 100 is started. At the same time, as a reference for comparison with the elapsed time tx, a fixed time point of the first switching time point t1s and the second switching time point t2s is set in advance. In addition, in the present embodiment, a predetermined time point, a storage start time point t0s described later, is set in advance before the first switching time point t1s, and the maximum standard weight described later is smaller than the supply stop weight value Wc. A constant weight value of value Ws [N] (<Wc) is preset.

  Specifically, the period from when the supply of the object 100 is started until the above-described elapsed time tx reaches the first switching time t1s is a large supply stage. In this large supply stage, as shown in FIG. 3A, the gate opening Gx is set to a relatively large constant value of Gx = G1. Accordingly, as indicated by a thick solid line X in FIG. 3B, the weight measurement value Wx increases at a relatively high speed according to the gate opening G1. In addition, the thick broken line Y in FIG.3 (b) shows transition of the true supplied weight value Wx '. Further, when the elapsed time tx reaches the storage start time t0s during the large supply stage, storage of the weight measurement value Wx for calculating the weight estimation value Wx ″ described later is started.

  When the elapsed time tx reaches the first switching time t1s, the large supply stage is switched to the gradual reduction stage. In the gradual reduction stage, the gate opening degree Gx is controlled based on a quadratic function expression shown in the following expression 3 using the elapsed time tx as a variable, strictly based on an expression 12 described later.

<< Formula 3 >>
Gx = a1 · tx ² + a2 · tx + a3

  In Equation 3, a1, a2, and a3 are all constants and are determined so that the following three conditions are satisfied. That is, as the first condition, it is required that Gx = G1 when tx = t1s. As a second condition, it is required that Gx = G2 when tx = t2s. G2 is the gate opening degree Gx in the small supply stage, and the gate opening degree G2 in the small supply stage is smaller than the gate opening degree G1 in the large supply stage (G2 <G1). Further, as a third condition, it is required that Gx = G1 ′s when tx = t1 ′s. Note that t1's is an intermediate time (not shown) set between the first switching time t1s and the second switching time t2s, G1's is smaller than the gate opening G1 in the large supply stage, and A predetermined value (G2 <G1s ′ <G1) not shown which is larger than the gate opening G2 in the small supply stage. The intermediate time point t1's and the gate opening degree G1's corresponding to the intermediate time point t1's will be described in detail later.

  Based on Formula 3, the gate opening Gx in the gradual decrease stage gradually decreases as the time tx elapses. Specifically, the gate opening Gx itself increases while gradually increasing its rate of change with respect to the elapsed time tx, that is, a gradually decreasing speed (| dGx / dtx | = | 2 · a1 · tx + a2 |; a1 <0). Changes so as to gradually decrease. Along with this, the increasing speed of the weight measurement value Wx also gradually decreases. When the elapsed time tx reaches the second switching time t2s, the gradual reduction stage is switched to the small supply stage. In the gradual decrease stage, the weight measurement value Wx at the second switching time point t2s, which is the end point thereof, strictly speaking, the estimated weight value Wx ″ [N] at the second switching time point t2s is the above-mentioned maximum standard. The gate opening Gx is appropriately controlled so as to coincide with the weight value Ws [N] (Wx ″ [N] = Ws [N]), that is, correction control (fine adjustment) is performed as necessary. The control point of the gate opening degree Gx in the gradual reduction step including the correction control will be described in detail later.

  In the small supply stage, the gate opening Gx is maintained at a constant value of Gx = G2. Accordingly, the weight measurement value Wx increases at a relatively low constant speed according to the gate opening degree G2. When the weight measurement value Wx matches the supply stop weight value Wc (Wx ≧ Wc), the gate opening Gx is set to Gx = 0 at the time t3, and the open / close gate is closed. As a result, the weight measurement value Wx increases by the drop amount Wd from the time point t3, and finally converges to the final weight value Wf (≈Wp) close to the target weight value Wp.

  When the final weight value Wf is obtained, specifically, when the weight measurement value Wx at the time t4 when the predetermined stabilization waiting time Tf has elapsed from the supply stop time t3 is acquired as the final weight value Wf, the final weight value Wf is displayed on the display 20 described above. Strictly speaking, the final weight value Wf is obtained by a moving average process as a second smoothing process based on the following equation 4.

<< Formula 4 >>
Wf = {ΣWx [i−j] / J} where j = 0 to {J−1}

  In Equation 4, i is an arbitrary sampling number by the A / D conversion circuit 26 shown in FIG. J is the number of taps, and more specifically, an arbitrary integer of 1 or more. In the multiple moving average process as the first smoothing process described above, a process based on the same arithmetic expression as Expression 4 is performed. Specifically, the moving average process with different tap numbers is performed continuously twice ( (Cascading). In addition, the moving average process based on Equation 4 attenuates a vibration component in a frequency band that is lower than that to be attenuated by the first smoothing process, for example, a vibration component in an extremely low frequency band of about 5 Hz such as floor vibration. Therefore, a lower notch frequency than that of the first smoothing process is formed (the number of taps J is set so as to be so). Then, in order to realize the moving average processing based on the equation 4, the weight measurement value Wx after the supply stop time t3 is sequentially stored in a register (not shown) having J storage areas. The same applies to the first smoothing process.

  After the final weight value Wf is obtained, the cylinder 38 described above is driven and the discharge gate 54 is opened. As a result, the object to be weighed 100 supplied to the weighing hopper 14 is discharged through the discharge gate 54 and stored in a packaging bag (not shown), for example. The discharge gate 54 is closed when the discharge of the object to be weighed 100 ends, specifically at the time t5 when a predetermined discharge time Tg has elapsed from the time t4 when the final weight value Wf is acquired. This completes a series of quantitative supply. Then, at the time t6 when a predetermined preparation time Th has elapsed from the time t5 when this series of quantitative supply is completed, the next quantitative supply is started. That is, the time point t6 is the start time (tx = 0) of the next quantitative supply.

  As described above, according to the present embodiment, as in the first and second prior arts described above, the gradual reduction stage is provided between the large supply stage and the small supply stage. Generation of vibration components at the first switching time point t1s and the second switching time point t2s, which are time points, is suppressed (however, the initial vibration component generated immediately after the supply of the object 100 is started is not suppressed. It seems that the vibration components generated at the first switching time t1s and the second switching time t2s are removed by performing the first smoothing process described above, but the amplitude of these vibration components is the time tx. Since it decays with the passage of time and the period also changes with the passage of time tx (that is, it is not a perfect sine wave), even if the first smoothing process is performed, it remains without being completely removed. It is, also, the same vibration component generated by supply stop time t3). In particular, since the generation of the vibration component at the second switching time t2s when switching from the gradual reduction stage to the small supply stage is suppressed, the small supply time T3 (= t3-t2s) can be shortened, and as a result The time Tw (= T1 + T2 + T3) can be shortened. In addition, the shortening of the small supply time T3 is because the weight measurement value Wx at the second switching time point t2s, that is, the above-described maximum standard weight value Ws [N] approaches the supply stop weight value Wc. This is realized by reducing the difference We (= Wc−Ws [N]) between the two Ws [N] and Wc, and in other words, by setting the second switching time t2s so as to be so. . Further, among the large supply time T1 (= t1s-0), the gradual decrease time T2 (= t2s-t1s) and the small supply time T3 constituting the total supply time Tw, the gradual decrease time T2 is usually the longest and the smallest. The supply time T3 is the shortest (T2> T1> T3) (strictly, it is set to be so).

  In addition, according to the present embodiment, the first switching time t1s at which the large supply stage is switched to the gradual reduction stage and the second switching time t2s at which the gradual reduction stage is switched to the small supply stage are constant. That is, the large supply time T1 and the gradual decrease time T2 that occupy most of the total supply time Tw are always constant. Moreover, the weight measurement value Wx at the second switching time t2s, which is also the starting point of the small supply stage, is a constant value (Wx≈Ws [N]) that is substantially equivalent to the maximum standard weight value Ws [N]. The gate opening degree Gx in the gradual reduction stage is controlled so as to be so. Therefore, for example, even if various conditions such as the properties of the object to be weighed 100 change and the relationship between the gate opening Gx and the supply amount Qx per unit time of the object to be weighed 100 changes, Unlike the first prior art and the second prior art, the total supply time Tw does not vary greatly. That is, the total supply time Tw is made uniform. In particular, unlike the second prior art, the supply accuracy does not decrease.

  This will be described in detail. The large supply time T1 and the gradual decrease time T2 that occupy most of the total supply time Tw are always constant. This means that only the remaining small supply time T3 is the total supply time. It becomes a fluctuation factor of time Tw. Here, the small supply time T3 is determined by the weight measurement value Wx at the second switching time t2s and the supply amount Qx per unit time of the weighing object 100 in the small supply stage. Among these, the former weight measurement value Wx at the second switching time t2s is a constant value substantially equivalent to the maximum standard weight value Ws [N] as described above. On the other hand, the supply amount Qx per unit time of the object to be weighed 100 in the latter small supply stage is determined by the gate opening G2 in the small supply stage. If the situation changes, it may change under the influence. However, the gate opening G2 in the small supply stage is originally small, and therefore the supply amount Qx in the small supply stage is also originally small. Therefore, even if various conditions such as the properties of the object to be weighed 100 change and the supply amount Qx in the small supply stage changes accordingly, the amount of change in the small supply time T3 due to this change is extremely small. Moreover, the small supply time T3 is originally short. Therefore, the small supply time T3 is substantially constant, and the total supply time Tw is also substantially constant.

  Furthermore, since the small supply time T3 is substantially constant as described above, a waiting time until the vibration component generated at the second switching time t2s that is the starting point is sufficiently attenuated is ensured. That is, at the supply stop time t3 that is the end point of the small supply time T2, the vibration component is sufficiently damped. Therefore, the supply stop time t3 is accurately obtained without being affected by the vibration component. As a result, supply accuracy that is always above a certain level (as expected) can be obtained.

  In order to bring about such a great effect, the gate opening Gx in the gradual reduction stage is appropriately controlled. The control of the gate opening Gx in the gradual reduction stage is realized by the following procedure.

  First, prior to actual operation operation, adjustment work including preliminary test operation is performed. For this purpose, the adjustment mode is selected by operating the operation key 42 described above. Subsequently, as shown in FIG. 4, a desired target weight value Wp and a supply stop weight value Wc commensurate with this (that is, considering the drop amount Wd) are set by operating the operation key 42. . In addition, the gate opening G1 in the large supply stage and the gate opening G2 in the small supply stage are set. Further, a temporary first switching weight value W1 and a temporary second switching weight value W2 are set. The provisional second switching weight value W2 is smaller than the supply stop weight value Wc, and the provisional first switching weight value W1 is further smaller than the provisional second switching weight value W2 (Wc> W2> W1). ). Further, a temporary intermediate weight value W1 '(= {W1 + W2} / 2) is set between the temporary first switching weight value W1 and the temporary second switching weight value W2, for example, in the middle. After such a setting is made, a provisional quantitative supply using the weight measurement value Wx as a control parameter is performed, so that a test operation is performed in the same manner as the quantitative supply according to the first prior art. Even in this test operation, the elapsed time tx with the starting point of supply of the object 100 to be measured as a base point is measured.

  That is, as shown in FIG. 4A, immediately after the supply of the object to be weighed 100 is started, the gate opening Gx is set to Gx = G1, and the provisional large supply stage is entered. In the provisional large supply stage, the gate opening G1 is maintained, and accordingly, as shown by a thick solid line X in FIG. 4B, the weight measurement value Wx is compared according to the gate opening G1. Increase at a very high rate. Note that the thick broken line Y in FIG. 4B shows the transition of the true supplied weight value Wx ′.

  When the weight measurement value Wx reaches the temporary first switching weight value W1 (Wx ≧ W1), the temporary large supply stage is switched to the temporary gradual reduction stage at the time t1. In addition, the time point t1 is stored as a temporary first switching time point (by the CPU 32 in the memory circuit 40), and strictly speaking, the elapsed time tx at the simultaneous point t1 is stored. In the provisional gradual reduction stage, the gate opening degree Gx is controlled based on the following formula 5 based on the formula 1 described above. It should be noted that the power index α in the formula 5 is an arbitrary value satisfying 0 <α ≦ 1.

<< Formula 5 >>
Gx = (G1-G2). {(W2-Wx) / (W2-W1)} ^α + G2

  Based on this equation 5, the gate opening Gx in the temporary gradual decrease step gradually decreases as the time tx elapses, strictly speaking, as the weight measurement value Wx increases. Along with this, the increasing speed of the weight measurement value Wx also gradually decreases. When the weight measurement value Wx reaches the temporary intermediate weight value W1 ′ (Wx ≧ W1 ′), the time point t1 ′ is stored as the temporary intermediate time point, strictly speaking, the elapsed time tx at the simultaneous point t1 ′ is stored. Is done. Further, when the weight measurement value Wx reaches the temporary second switching weight value W2 (Wx ≧ W2), the time point t2 is stored as the temporary second switching time point, and strictly speaking, the elapsed time tx at the simultaneous point t2 is stored. Is done. At the same time, the temporary gradual reduction stage is switched to the temporary small supply stage. The gate opening Gx at the temporary second switching time t2 is Gx = G2, as can be seen from Equation 5.

  In the temporary small supply stage, the same gate opening G2 as that at the temporary second switching time t2 is maintained, and accordingly, the weight measurement value Wx is a relatively low constant speed corresponding to the gate opening G2. Increase with. When the weight measurement value Wx matches the supply stop weight value Wc (Wx ≧ Wc), the gate opening Gx is set to Gx = 0 at the time t3. Furthermore, the final weight value Wf is acquired at the time t4 when the above-described stabilization waiting time Tf has elapsed from the supply stop time t3. The acquired final weight value Wf is displayed on the display 20. The final weight value Wf displayed on the display 20 is collated with the target weight value Wp. Then, based on the collation result, the gate opening G1 at the large supply stage, the gate opening G2 at the small supply stage, the provisional first switching weight value W1, the provisional second switching weight value W2, and the supply stop weight value Wc. And the suitability of each setting condition such as the power index α in Equation 5 is confirmed. Further, if necessary, that is, if the difference between the final weight value Wf and the target weight value Wp (= Wp−Wf) exceeds a predetermined allowable range, each setting condition is set so that the difference is minimized. Are appropriately changed. At that time, an effort is also made to make the total supply time Tw from the supply start time to the supply stop time t3 as short as possible. Since the changing procedure of each setting condition is not directly related to the gist of the present invention, further detailed description is omitted.

  After obtaining the final weight value Wf, the discharge gate 54 is opened at an appropriate time. Thereby, the object 100 to be weighed in the weighing hopper 14 is discharged. Then, at an appropriate time after the discharge, the discharge gate 54 is closed and returns to the original state. This completes a series (one time) of test operations.

  By performing the test operation in this manner, a temporary first switching time point t1, a temporary intermediate time point t1 ', and a temporary second switching time point t2 are obtained. Further, by substituting the temporary intermediate weight value W1 'for the weight measurement value Wx of Equation 5, the gate opening G1' at the temporary intermediate time point t1 'is obtained.

  Here, in Equation 3 above, the first condition that Gx = G1 when tx = t1, the second condition that Gx = G2 when tx = t2, and tx = t1 The constants a1, a2, and a3 in Equation 3 are obtained so that the third condition of Gx = G1 ′ when “3” is satisfied. As a result, the control expression of the gate opening degree Gx in the temporary gradual reduction stage is converted from Expression 5 using the weight measurement value Wx as a variable to Expression 3 using the elapsed time tx as a variable.

  However, since the weight measurement value Wx in Equation 5 is affected by the vibration component including the initial vibration component described above, the gate opening degree Gx is controlled based on Equation 5 using the weight measurement value Wx as a variable. Then, the gate opening degree Gx is also affected by the vibration component. Then, the provisional first switching time t1, the provisional intermediate time t1 ′ and the provisional second switching time t2 necessary for the conversion from Expression 5 to Expression 3 cannot be obtained accurately, and the conversion becomes inappropriate. . In order to avoid such an inconvenience, a weight estimation value Wx ″ described below is applied instead of the weight measurement value Wx in Equation 5.

  This estimated weight value Wx ″ is obtained by estimating the true supplied weight value Wx ′ as a function of the elapsed time tx, and is based on the past {β + 1} (β: integer of 1 or more) weight measurement values Wx. Specifically, as shown in Fig. 5, the weight measurement values Wx obtained for each period ΔT of the clock pulse CLK described above are sequentially stored every γ (γ; an integer of 1 or more), In other words, the data are sequentially stored in a cycle of Td = γ · ΔT, and at the past {β + 1} timings {k−β} to k including a certain timing k (k: storage order of the weight measurement value Wx). Based on the stored {β + 1} weight measurement values Wx <k−β> to Wx <k>, the estimated weight value Wx ″ <k> at the same timing k is obtained. That is, the estimated weight value Wx ″ <k> at a certain timing k is obtained based on the measured weight values Wx <k−β> to Wx <k> for a period of Tc = β · Td.

  It is to be noted that the {β + 1} weight measurement values Wx <k−β> to Wx <k> necessary for calculating the weight estimated value Wx ″ <k> at a period of Tc, that is, at a certain timing k. The estimation weight value acquisition period for acquisition is set to be longer than the natural vibration period To of the weighing system including at least the weighing hopper 14 (Tc> To), and more specifically, longer than the longest natural vibration period Tomax of the weighing system. For example, the maximum natural vibration period Tomax of the scale system is Tomax = 100 msec, and the integer γ related to the storage period of the above-described weight measurement value Wx called Td is γ = 10. In this case, since the storage cycle Td is Td = γ · ΔT = 10 msec (∵ΔT = 1 msec), the integer β related to the estimation weight value acquisition period Tc is β ≧ 11. If so, the estimation weight value acquisition period Tc is Tc = β · Td ≧ 110 msec, which is longer than the longest natural vibration period Tomax (= 100 msec). By setting longer than the natural vibration period Tomax, the influence of the natural vibration of the scale system that causes an error in calculating the weight estimated value Wx ″ <k> is suppressed, and thus a more accurate weight estimated value. Wx ″ <k> is obtained. However, if the estimation weight value acquisition period Tc is too long, it takes a corresponding time until the (especially first) weight estimation value Wx ″ <k> is obtained. Responsiveness deteriorates. Therefore, the estimation weight value acquisition period Tc is preferably shorter than twice the longest natural vibration period Tomax (Tc <2 · Tomax), for example, 1.1 times to 1.3 times the longest natural vibration period Tomax. It is preferable that it is about double (1.1 · Tomax ≦ Tc ≦ 1.3 · Tomax).

  The calculation procedure of the estimated weight value Wx ″ <k> at a certain timing k will be described more specifically. The estimated weight value Wx ″ <k> at the certain timing k is a linear function of the following equation (6). It is expressed by an equation (linear equation). In Equation 6, b1 <k> and b2 <k> are constants at a certain timing k.

<< Formula 6 >>
Wx ″ <k> = b1 <k> · k + b2 <k>

  And in order to obtain | require two constants b1 <k> and b2 <k> which comprise this Formula 6, the following Formula 7 based on the said Formula 6 is assembled.

<< Formula 7 >>
f <tx> = b1 <k> .tx + b2 <k>

  Furthermore, in this equation 7, the past {β + 1} weight measurement values Wx <k−β> to Wx <k> are substituted for f <tx> on the left side, and these are assigned to the variable tx on the right side. By substituting the respective timing values {k−β} to k corresponding to the weight measurement values Wx <k−β> to Wx <k>, {β + 1} primarys as in the following Expression 8: A function expression is assembled.

<< Formula 8 >>
Wx <k−β> = b1 <k> · {k−β} + b2 <k>
Wx <k−β + 1> = b1 <k> · {k−β + 1} + b2 <k>
:
Wx <k-1> = b1 <k>. {K-1} + b2 <k>
Wx <k> = b1 <k> .k + b2 <k>

  Then, constants b1 <k> and b2 <k> common to the linear function expressions are obtained by a regression analysis method using these {β + 1} linear function expressions, for example, by the least square method. Note that the constants b1 <k> and b2 <k> may be obtained not only by the method of least squares but also by other regression analysis methods or calculation methods other than the regression analysis method. However, according to the regression analysis method such as the least square method, the constants b1 <k> and b2 <k> are obtained without causing a (large) time delay, and the weight estimated value Wx ″ <k> is eventually obtained. Desired.

  When the constants b1 <k> and b2 <k> at a certain timing k are obtained in this way, the constants b1 <k> and b2 <k> are substituted into the above equation 6. Thus, the estimated weight value Wx ″ <k> at the certain timing k is obtained. In the same manner, the estimated weight values Wx ″ <k + 1> and Wx ″ <k + 2 after the next timing {k + 1}. In other words, the estimated weight value Wx ″ is sequentially obtained at the same period as the storage period of the above-described weight measurement value Wx called Td.

  In calculating the estimated weight value Wx ″, as shown in FIG. 6, a temporary storage start weight value W0 (<W1) smaller than the temporary first switching weight value W1 is set in advance. At the time t0 when the value Wx reaches the temporary storage start weight value W0 (Wx ≧ W0), the storage of the weight measurement value Wx for calculating the weight estimated value Wx ″ is started. Therefore, for example, the first estimated weight value Wx ″ <β> is stored at the time when the estimation weight value acquisition period Tc described above has elapsed from the time t0 when the weight measurement value Wx is stored. At the time t0 ′ when the {β + 1} weight measurement values Wx <0> to Wx <β> including the weight measurement value Wx <0> are stored (strictly, an estimated calculation time elapses from this time t0 ′) The second and subsequent estimated weight values Wx ″ <β + 1>, Wx ″ <β + 2>,... Are sequentially obtained at a period of Td as described above from the time point t0 ′. It is done.

  FIG. 6 illustrates the case where the integer β is β = 9. In FIG. 6, a straight line labeled L0 is a linear function straight line that follows the above-described equation 7 and passes through the first estimated weight value Wx ″ <β>. The straight line is a linear function line according to Equation 7 that passes through the second estimated weight value Wx ″ <β + 1>, and the straight line labeled L2 is the third estimated weight value Wx ″ <β + 2>. Is a linear function line according to the equation 7. Further, as can be seen from FIG.6, the first weight estimated value Wx ″ <β>, the second weight estimated value Wx ″ <β + 1>, and the third weight. An estimated initial weight estimated value Wx ″ such as an estimated value Wx ″ <β + 2> usually deviates from the true supplied weight value Wx ′ indicated by the thick broken line Y. However, the weight indicated by the thick solid line X Compared with the measured value Wx, the estimated initial weight value Wx " Generally it is closer to the true been supplied weight value Wx '. The estimated weight value Wx ″ approaches the true supplied weight value Wx ′ as the time tx elapses. For example, the estimated weight value Wx ″ itself reaches the temporary first switching weight value W1 ( When Wx ″ ≧ W1), the actual supplied weight value Wx ′ is substantially equivalent (Wx ″ ≈Wx ′).

  Here, the test operation will be described again. As shown in FIG. 7A, immediately after the supply of the object to be weighed 100 is started, the gate opening Gx is set to Gx = G1, and the provisional large supply stage starts. In the provisional large supply stage, the gate opening G1 is maintained, and accordingly, as shown by a thick solid line X in FIG. 7B, the weight measurement value Wx is compared according to the gate opening G1. Increase at a very high rate. Note that the thick broken line Y in FIG. 7B shows the transition of the true supplied weight value Wx ′.

  When the weight measurement value Wx reaches the temporary storage start weight value W0, the storage of the weight measurement value Wx for calculating the weight estimated value Wx ″ is started at the time t0. t0 is stored as the tentative first switching time point, strictly speaking, the elapsed time tx at the simultaneous point t0 is stored, although not shown in FIG. At the time point t0 ′ when the value acquisition period Tc has elapsed, the first estimated weight value Wx ″ <β> is obtained as shown in FIG. Thereafter, the estimated weight value Wx ″ is sequentially obtained at a period of Td.

  When the estimated weight value Wx ″ reaches the temporary first switching weight value W1 (Wx ″ ≧ W1), at the time t1, the temporary large supply stage is switched to the temporary gradual decrease stage. In addition, the time t1 is stored as a temporary first switching time. However, since the estimated weight value Wx ″ is obtained at a period of Td (= γ · ΔT) as described above, the estimated weight value Wx ″ at the temporary first switching time point t1 is the temporary first switching weight value W1. May not match. That is, as shown in FIG. 6 described above, for example, at a certain timing of k ′, when the weight estimated value Wx ″ becomes the first switching weight value W1 or more (Wx ′ <k ′> ≧ W1) for the first time, The timing k ′ is specified as the tentative first switching time t1, and in order to specify the tentative first switching time t1 in this way, at least before the tentative first switching time t1. It is necessary to obtain one or more estimated weight values Wx ″, in other words, the provisional storage start weight value W0 needs to be set so as to be.

  In the provisional gradual reduction stage, the gate opening degree Gx is controlled based on the following equation 9 to which the estimated weight value Wx ″ is applied instead of the weight measurement value Wx in the above-described equation 5.

<< Formula 9 >>
Gx = (G1-G2). {(W2-Wx ″) / (W2-W1)} ^α + G2

  Based on Equation 9, the gate opening Gx in the tentative gradual decrease step gradually decreases as the estimated time value Wx ″ increases as the time tx elapses. The rate of increase of the weight estimate Wx ″ also decreases gradually. When the estimated weight value Wx ″ reaches the temporary intermediate weight value W1 ′ (Wx ″ ≧ W1 ′), the time point t1 ′ is stored as a temporary intermediate time point. Further, when the estimated weight value Wx ″ reaches the temporary second switching weight value W2 (Wx ″ ≧ W2), the time point t2 is stored as the temporary second switching time point. At the same time, the temporary gradual reduction stage is switched to the temporary small supply stage. The gate opening Gx at the temporary second switching time t2 is Gx = G2, as can be seen from Equation 9. At the temporary second switching time point t2, the calculation of the estimated weight value Wx ″ (estimation of the true supplied weight value Wx ′) is completed, and the measured weight value for calculating the estimated weight value Wx. Wx storage is terminated.

  In the temporary small supply stage, the gate opening G2 equivalent to that at the temporary second switching time t2 is maintained, and accordingly, the weight measurement value Wx is a relatively low constant corresponding to the gate opening G2. Increases at a speed of When the weight measurement value Wx matches the supply stop weight value Wc, the gate opening degree Gx is set to Gx = 0 at the time t3. The subsequent steps are the same as described with reference to FIG.

  By performing the test operation in this manner, as described above, the temporary first switching time point t1, the temporary intermediate time point t1 ′, and the temporary second switching time point t2 are obtained, and the temporary intermediate time point t1 ′. The gate opening G1 ′ at is obtained. In addition, a temporary storage start time t0 is obtained.

  Then, by repeating this test operation a plurality of times, the provisional storage start time t0, the provisional first switching time t1, the provisional intermediate time t1 ′, the provisional second switching time t2, and the provisional intermediate time t1 ′. A plurality of gate openings G1 ′ are obtained. During this time, when various conditions such as the properties of the object to be weighed 100 change, the temporary storage start time t0, the temporary first switching time t1, the temporary intermediate time t1 ′, and the temporary second switching time t2 respectively. Results in different results. However, the gate opening G1 'at the temporary intermediate time point t1' is constant (invariable). Furthermore, the gate opening G1 ′ at the temporary storage start time t0, the temporary first switching time t1, the temporary intermediate time t1 ′, the temporary second switching time t2, and the temporary intermediate time t1 ′. Average values t0m, t1m, t1′m, t2m and G1′m are obtained. The average values t0m, t1m, t1′m, t2m and G1′m are, for example, the formal storage start time t0, first switching time t1s, intermediate time t1 ′s, second switching time t2s and intermediate time t1 ′. It is determined as the gate opening G1′d at s. The formal storage start time t0, the first switching time t1s, the intermediate time t1 ′s, and the second switching time t2s are determined so as to be synchronized with the calculation timing of the weight estimated value Wx ″ according to the period Td described above. In other words, the time from the storage start time t0 to the first switching time t1s, the intermediate time t1 ′s, and the second switching time t2s is determined to be divisible by the period Td.

  Then, again, the first condition that Gx = G1 when tx = t1, the second condition that Gx = G2 when tx = t2, and the time when tx = t1 ′. The constants a1, a2, and a3 in Expression 3 are obtained so that the third condition of Gx = G1 ′ and the third condition are satisfied. Thereby, the conversion from the equation 9 using the estimated weight value Wx ″ as a variable to the equation 3 using the elapsed time tx as a variable is appropriately performed.

  Then, this time, a test operation using the appropriately converted Equation 3 is performed, that is, a second test operation.

  In other words, the storage start time t0s, the first switching time t1s, and the second switching time t2s determined by the first test operation are set in advance as shown in FIG. At the same time, the gradual decrease time T2 from the first switching time point t1s to the second switching time point t2s is divided by N (= T3 / Td) by dividing it by the calculation period of the weight estimated value Wx ″ Td described above. Then, the time point corresponding to the boundary between the N equally divided sections is set as the reference time point t [n] (n = 0 to N), that is, the first switching time point t1s is set as the first reference time point t. [0], and the second switching time t2s is the last reference time t [N], and {N + 1} reference times t [n] are set at equal intervals. Then, the second test operation using the elapsed time tx as a control parameter is started, and also in this second test operation, the elapsed time tx starting from the supply start time of the object 100 is measured. The

  Specifically, as shown in FIG. 8A, immediately after the supply of the object to be weighed 100 is started, the gate opening Gx is set to Gx = G1, and the large supply stage is entered. In the large supply stage, the gate opening degree G1 is maintained. As a result, as indicated by a thick solid line X in FIG. 8B, the weight measurement value Wx increases at a relatively high speed according to the gate opening G1. In addition, the thick broken line Y in FIG.8 (b) shows transition of the true supplied weight value Wx '.

  When the elapsed time tx reaches the storage start time t0s, storage of the weight measurement value Wx for estimating the weight estimated value Wx ″ is started. Further, when the elapsed time tx reaches the first switching time t1s. In this second test operation, the weight estimated value Wx ″ according to the above-described procedure is not used at the first switching time t1s, but at the time t0 ′ shown in FIG. Calculation starts. Further, the estimated weight value Wx ″ at the first switching time point t1s, that is, the estimated weight value Wx ″ [0] at the first reference time point t [0] is ideally set to the temporary first switching weight value W1. This is equivalent (Wx ″ [0] = W1), and the estimated weight value Wx ″ [0] is stored in a state associated with the first reference time point t [0].

  In the gradual reduction stage, the gate opening degree Gx is controlled based on the above-described (appropriately converted) Equation 3. As a result, the gate opening Gx gradually decreases as time tx elapses. At the same time, the estimated weight value Wx ″ also gradually decreases. Each time the elapsed time tx reaches each reference time point t [n], the estimated weight value Wx ″ [n] is obtained. "[N] is stored in a state associated with the reference time point t [n]. When the elapsed time tx reaches the second switching time point t2s that is the last reference time point t [N], it is gradually decreased. The estimated weight value Wx ″ [N] at the second switching time t2s is ideally equivalent to the temporary second switching weight value W2 (Wx ″ [N] = The gate opening Gx at the second switching time t2s is Gx = G2. At the second switching time t2s, the calculation of the estimated weight value Wx ″ is completed, and Measured weight value W for calculation of estimated weight value Wx Storage of is terminated.

  In the small supply stage, the gate opening G2 equivalent to that at the second switching time t2s is maintained, and accordingly, the weight measurement value Wx increases at a relatively low constant speed corresponding to the gate opening G2. . When the weight measurement value Wx matches the supply stop weight value Wc, the gate opening degree Gx is set to Gx = 0 at the time t3. The subsequent steps are the same as in the first test operation. The final weight value Wf is also stored.

  By performing the second test operation in this way, the estimated weight value Wx ″ [n] at each reference time t [n] in the gradually decreasing stage is stored, and the final weight value Wf is also stored. Then, this second test operation is repeated a plurality of times.

  Of the plurality of test results obtained by the plurality of second test operations, the estimated weight value Wx ″ [N] at the second switching time t2s (= t [N]) is within a predetermined allowable range. Only certain ones, specifically those satisfying the following expression 10, are extracted, where ΔWa in this expression 10 is an error weight allowed as a weight estimated value Wx ″ [N] at the second switching time t2s. For example, it is a few percent of the provisional second switching weight value W2, and is approximately 0.5% to 2% (ΔWa = 0.005 · W2 to 0.02 · W2).

<< Formula 10 >>
W2−ΔWa ≦ Wx ″ [N] ≦ W2 + ΔWa

  Further, only test results with final supply accuracy of a certain level or more, specifically those with final weight value Wf satisfying the following equation 11 are extracted from the test results satisfying this equation 10. Note that ΔWb in this equation 11 is an error weight value different from the above-described allowable weight value as the final weight value Wf, and is, for example, several percent of the target weight value Wp, and is approximately 0.5% to 2% (ΔWb = 0.005 · Wp to 0.02 · Wp).

<< Formula 11 >>
Wp ≦ Wf ≦ Wp + ΔWb

  Thus, after only the test results that satisfy both Expression 10 and Expression 11 are extracted, the weight estimation value Wx ″ [n] of the extracted test results is determined for each reference time point t [n]. An average value Wm ″ [n] is obtained. The average value Wm ″ [n] is determined as a standard value of the estimated weight value Wx ″ at each reference time point t [n], that is, a standard weight value Ws [n].

  The standard weight value Ws [n] is stored in, for example, a reference table shown in FIG. 9 in a state associated with each reference time t [n]. Further, by substituting each reference time t [n] for the variable tx in the above-described equation 3, the standard value of the gate opening Gx at each reference time t [n], that is, the standard gate opening Gs [ n], is determined. The standard gate opening Gs [n] is also stored in the reference table. The minimum standard weight value Ws [0] in this reference table is basically equivalent to the temporary first switching weight value W1 (Ws [0] = W1). The maximum standard weight value Ws [N] is forcibly equivalent to the provisional second switching weight value W2 (Ws [N] = W2). The standard gate opening Gs [0] at the first reference time t [0] is equivalent to the gate opening G1 in the large supply stage (Gs [0] = G1), and the last reference time t [N]. ] Is equivalent to the gate opening G2 in the small supply stage (Gs [N] = G2).

  When this reference table is completed, the previous adjustment work is completed. Thereby, an actual operation operation becomes possible.

  This actual operation operation will be described again. First, the operation mode is selected by operating the operation key 42. Then, the supply of the object to be weighed 100 is started, and the elapsed time tx with the starting point of the supply of the object to be weighed 100 as a base point is measured.

  Immediately after the supply of the object to be weighed 100 is started, the gate opening Gx is set to Gx = G1 as shown in FIG. In the large supply stage, the gate opening degree G1 is maintained. As a result, as indicated by a thick solid line X in FIG. 3B, the weight measurement value Wx increases at a relatively high speed according to the gate opening G1.

  When the elapsed time tx reaches the storage start time t0s, storage of the weight measurement value Wx for estimating the weight estimated value Wx ″ is started. Further, the elapsed time tx is set to the first switching time t1s. When it reaches, the large supply phase is switched to the gradual reduction phase. At the same time as in the second test described above, at the first reference time point t [0] that is the first switching time point t1s, the estimated weight value Wx ″ Calculation starts. Ideally, the estimated weight value Wx ″ [0] at the first reference time point t [0] is equivalent to the minimum standard weight value Ws [0] (Wx ″ [0] = Ws [0]). Depending on various conditions such as the properties of the object to be weighed 100, this may not occur. Therefore, the gate opening degree Gx [n] (here, Gx [0]) is controlled based on the following Expression 12.

<< Formula 12 >>
Gx [n] = Gs [n] −ε · (Wx ″ [n] −Ws [n])

  In Equation 12, ε is for converting the difference between the estimated weight value Wx ″ [n] and the standard weight value Ws [n] at an arbitrary reference time t [n] into the gate opening Gx [n]. Strictly speaking, this coefficient is a coefficient for converting the difference into a corrected amount of the gate opening Gx [n], and this conversion coefficient ε is obtained by the following equation 13, for example. The conversion coefficient ε may be arbitrarily set according to the control situation.

<< Formula 13 >>
ε = G2 / (Wc−W2)

  According to Equation 12 including the conversion coefficient ε of Equation 13, when the estimated weight value Wx ″ [0] is equivalent to the minimum standard weight value Ws [0] at the first reference time point t [0], the gate The opening Gx [0] is equivalent to the maximum standard gate opening Gs [0] (Gx [0] = Gs [0]), whereas the estimated weight value Wx ″ [0] is the minimum standard weight value. If it is larger than Ws [0] (Wx ″ [0]> Ws [0]), the gate opening Gx [0] is smaller than the maximum standard gate opening Gs [0] (Gx [0] <Gs In other words, the estimated weight value Wx ″ [0] is smaller than the minimum standard weight value Ws [0] (Wx ″ [0] <Ws [0]. ), The gate opening Gx [0] is equivalent to the maximum standard gate opening Gs [0].

  Similarly, until the elapsed time tx reaches the last reference time t [N], the elapsed time tx reaches each reference time t [n] (n = 1 to {N−1}). Every time, the gate opening degree Gx [0] is controlled based on the above equation 12. That is, at an arbitrary reference time point t [n], for example, when the estimated weight value Wx ″ [n] is equivalent to the standard weight value Ws [n] (Wx ″ [n] = Ws [n]), Gx [n] is equivalent to the standard gate opening Gs [n] (Gx [n] = Gs [n]). On the other hand, when the estimated weight value Wx ″ [n] is larger than the standard weight value Ws [n] (Wx ″ [n]> Ws [n]), the gate opening Gx [n] is the standard gate. The opening is smaller than Gs [n] (Gx [n] <Gs [n]). On the other hand, when the estimated weight value Wx ″ [n] is smaller than the standard weight value Ws [n] (Wx ″ [n] <Ws [n]), the gate opening Gx [n] is the standard value. The gate opening is larger than Gs [n] (Gx [n]> Gs [n]).

  When the elapsed time tx reaches the second switching time t2s, which is the last reference time t [N], the gate opening Gx [N] is forcibly equivalent to the maximum standard gate opening Gs [N] (Gx [N] = Gs [N]). By appropriately controlling the gate opening Gx in this way, the estimated weight value Wx ″ [n] at the second switching time t2s is substantially equivalent to the maximum standard weight value Ws [N] (Wx ″ [N]). ≈Ws [n]). On the other hand, since the vibration component including the initial vibration component described above is sufficiently attenuated at the second switching time t2s, the weight measurement value Wx at the second switching time t2s is the weight estimated value Wx ″ [ N] and substantially equivalent (Wx = Wx ″ [N]). As a result, as described above, the weight measurement value Wx at the second switching time t2s becomes a constant value substantially equivalent to the maximum standard weight value Ws [N]. Then, at the second switching time t2s, the calculation of the estimated weight value Wx ″ is completed and the storage of the measured weight value Wx for calculating the estimated weight value Wx is completed. The operation is switched to the small supply stage, as described above.

  Thus, according to the present embodiment, every time the elapsed time tx from the supply start time of the weighing object 100 reaches the respective reference time t [n] in the gradual reduction stage, the above-described Expression 12 is used. The gate opening Gx is controlled. This is because the weight estimated value Wx ″ [n] is compared with the standard weight value Ws [n] at each reference time point t [n], and both the Wx ″ [n] and Ws [n] match each other. In other words, it means that the gate opening Gx is appropriately controlled, that is, real-time controlled so that the estimated weight value Wx ″ [n] changes as expected. By the real-time control of the gate opening Gx, the weight measurement value Wx becomes the maximum standard weight value Ws [n] at a predetermined second switching time t2s that is the end point of the gradual reduction stage and the start point of the small supply stage. As a result, the total supply time Tw is made uniform, that is, the number of executions of the quantitative supply per unit time is made uniform. Supply device 1 In the system weight sorting apparatus described above to the subsequent is provided, to satisfy both the quality and productivity of products, it is extremely effective.

  In order to realize quantitative supply including real-time control of the gate opening Gx in such a gradual reduction stage, the CPU 32 operates as follows according to the control program described above during operation. In this operation, the open / close gate 16 is closed, and the reservoir hopper 12 contains a predetermined amount (accommodating height H) of the object 100 to be weighed. In addition, it is assumed that the weighing hopper 14 is empty and the discharge gate 54 is closed.

  First, when an automatic operation ON command is input by operating the operation key 42, the CPU 32 proceeds to step S1 of the automatic operation task shown in FIG. In step S1, an initial setting process is performed. Specifically, the count values of three counters Cd, Cf, and Cg, which will be described later, are all reset (set to 0), and each of the seven flags F0, F1, F2, F3, F4, F5, and F6, which will be described later, is set. Set to 0. And after execution of this step S1, it progresses to step S3 and starts execution of the interruption task mentioned later.

  Further, the CPU 32 proceeds to step S5 to prepare for setting the gate opening degree Gx to Gx = G1, and in detail prepares to generate the above-described gate control signal Sg. In step S7, the gate control signal Sg is generated, that is, the open / close gate 16 is controlled. This starts the large supply phase.

  After execution of step S7, the CPU 32 proceeds to step S9. In step S9, the count value of the counter Cu is reset. The count value Cu is for capturing the above-described storage start time t0s. Specifically, the storage start waiting time Tu (= t0s− from the supply start time of the object 100 to the storage start time t0s is described in detail. 0; see FIG. 3).

  Then, the CPU 32 proceeds to step S11 and sets 1 to the flag F0. The flag F0 is an index indicating whether or not the supply of the weighing object 100 from the reservoir hopper 12 to the weighing hopper 14 is started. For example, when the flag F0 is F0 = 1, the weighing object 100 Indicates that the supply has started. On the other hand, when the supply start flag F0 is F0 = 0, this means that the supply of the object 100 is not started.

  After executing step S11, the CPU 32 proceeds to step S13, and determines whether or not the elapsed time tx from the supply start time of the object 100 has reached the storage start time t0s. Specifically, the count value Cu for counting the storage start waiting time Tu and the storage start waiting time Tu (strictly, a count conversion value corresponding to a value obtained by dividing the storage start waiting time Tu by the sampling period ΔT). And compare. The count value Cu is managed in an interrupt task as will be described later. When the count value Cu reaches the storage start waiting time Tu (Cu ≧ Tu), that is, when the elapsed time tx reaches the storage start time t0s, the CPU 32 proceeds from step S13 to step S15.

  In step S15, the CPU 32 sets 1 to a flag called F1. This flag F1 is an index indicating whether or not the storage of the weight measurement value Wx for calculating the estimated weight value Wx ″ is started. For example, when the flag F1 is F1 = 1, the weight measurement value On the other hand, when the estimation start flag F1 is F1 = 0, this means that the storage of the weight measurement value Wx has not been started yet.

  Then, the CPU 32 proceeds to step S17 to determine whether or not the elapsed time tx has reached the first switching time t1s. Specifically, an index value k indicating the storage order of the weight measurement value Wx for estimation of the weight estimation value Wx ″ described with reference to FIGS. 5 and 6, a predetermined reference value R, Note that the value of the index k is managed in the interrupt task, and the reference value R is the estimated waiting time Tr (= t1s−t0s; from the storage start time t0s to the first switching time t1s; 3) is converted into the value of the index k and corresponds to, for example, the value of k ′ in FIG 6. In this step S17, the value of the index k reaches the reference value R (k ≧ R). In other words, when the elapsed time tx reaches the first switching time t1s, the CPU 32 proceeds to step S19 in FIG. 11 in order to switch from the large supply stage to the gradual reduction stage.

  In step S19, the CPU 32 sets 0 to an index different from the above-mentioned n for specifying the weight estimated value Wx ″ [n] at an arbitrary reference time point t [n], and proceeds to step S21. The index value k is copied to the count value of the counter Cp, that is, the value R is set in the count value Cp in step S21. As such, it is used to update the weight estimate Wx ″.

  After executing step S21, the CPU 32 proceeds to step S23, and compares the value of the index k with the count value Cp described above. This step S23 is repeated until the value of the index k becomes equal to or greater than the count value Cp (k ≧ Cp). When the value of the index k becomes equal to or greater than the count value Cp, the CPU 32 proceeds to step S25 to calculate the weight estimated value Wx ″. When this step S23 is executed for the first time, the above-described step S21 is performed. Since it is immediately after execution, the value of the index k and the count value Cp are both R (k = Cp = R). Therefore, the CPU 32 immediately proceeds to step S25.

  In step S <b> 25, the CPU 32 includes the past {β + 1} pieces of weight measurement values Wx <k> of the currently stored weight measurement values Wx including the most recently stored weight measurement value Wx <k>. Based on the measured weight values Wx <k−β> to Wx <k>, an estimated weight value Wx ″ <k> at the current timing of k is obtained. Based on β + 1} linear function expressions, two constants b1 <k> and b2 <k> common to these linear function expressions are obtained, and these two constants b1 <k> and b2 <k> are obtained. Is substituted into Equation 6 to obtain the estimated weight value Wx <k>.

  The CPU 32 then proceeds to step S27 and replaces the estimated weight value Wx ″ <k> obtained in step S25 with the estimated weight value Wx ″ [n] specified by the index n described above. Further, the CPU 32 proceeds to step S29 and specifies the standard weight value Ws [n] and the standard gate opening degree Gs [n] corresponding to the index n by referring to the reference table shown in FIG. Then, the process proceeds to step S31, where the gate opening degree Gx [n] is calculated based on the above equation 12, and the process proceeds to step S33, where a gate control signal Sg corresponding to the gate opening degree Gx [n] is generated. To do. Thereby, real-time control of the gate opening degree Gx is realized.

  After execution of step S33, the CPU 32 proceeds to step S35 and increments the index value n by one. In step S37, the value of the index n after the increment is compared with the maximum value N. Here, for example, when the value of the index n is smaller than the maximum value N (n <N), that is, when the elapsed time tx has not yet reached the last reference time t [n], which is the second switching time t2s. Advances to step S39 to newly calculate the estimated weight value Wx ″ [n]. In step S39, the count value Cp for updating the estimated weight value Wx ″ [n] is incremented by 1. Then, the process returns to step S23. On the other hand, when the value of the index n reaches the maximum value N (n = N), that is, when the elapsed time tx reaches the last reference time t [N], the process proceeds from step S37 to step S41.

  In step S41, the CPU 32 prepares to generate a gate control signal Sg for setting the gate opening degree Gx to Gx = G02. In step S43, the gate control signal Sg is generated and the open / close gate 16 is controlled. As a result, the gradual reduction stage is switched to the small supply stage.

  Further, the CPU 32 proceeds to step S45 and sets 1 to a flag F2. This flag F2 is an index indicating whether or not the small supply stage has already been entered. For example, when the flag F2 is F2 = 1, it indicates that the small supply stage has already been entered. On the other hand, when the small supply start flag F2 is F2 = 0, this means that the small supply stage has not yet been entered. After executing step S45, the CPU 32 proceeds to step S47 in FIG.

  In step S47, the CPU 32 compares the weight measurement value Wx with the supply stop weight value Wc. This step S47 is repeated until the weight measurement value Wx is equal to or greater than the supply stop weight value Wc (Wx ≧ Wc). When the weight measurement value Wx becomes equal to or greater than the supply stop weight value Wc, the CPU 32 proceeds from step S47 to step S49 in order to close the open / close gate 16.

  In step S49, the CPU 32 prepares to generate a gate control signal Sg for setting the gate opening Gx to Gx = 0. In step S51, the gate control signal Sg is generated and the open / close gate 16 is controlled. Thereby, the open / close gate 16 is closed.

  Then, the CPU 32 proceeds to step S53 and sets 1 to the flag F3. This flag F3 is an index indicating whether or not the stabilization waiting operation for obtaining the final weight value Wf described above has been started. In other words, the stabilization waiting time Tf described with reference to FIG. It is an index indicating whether or not it is in the middle. For example, when the stabilization waiting start flag F3 is F3 = 1, this indicates that the stabilization waiting operation has started, that is, the stabilization waiting time Tf is being measured. On the other hand, when this is not the case, the stabilization waiting start flag F3 is F3 = 0.

  After executing step S53, the CPU 32 proceeds to step S55. In step S55, it is determined whether the flag F4 is F4 = 1. This flag F4 is an index indicating whether or not the above-described stabilization waiting operation has been completed, and is managed by an interrupt task. For example, when the stabilization wait end flag F4 is F4 = 1, this means that the stabilization wait operation has ended, and when the flag F4 is F4 = 0, the stabilization wait operation has not yet ended. Represents. This step S55 is continued until the stabilization waiting end flag F4 becomes F4 = 1, that is, until the stabilization waiting operation ends. When the stabilization waiting operation is completed, the CPU 32 proceeds from step S55 to step S57.

  In step S57, the CPU 32 calculates the final weight value Wf by the moving average process as the second smoothing process based on the above-described formula 4. In step S59, the final weight value Wf calculated in step S57 is displayed on the display 20. Although the detailed illustration is omitted, the display of the final weight value Wf on the display 20 is performed over a certain period, for example, until immediately before the next quantitative supply is started. The final weight value Wf can also be output to an external device (not shown) such as a printing device or a sorting device.

  After execution of step S59, the CPU 32 proceeds to step S61, controls the cylinder 38 to open the discharge gate 54, that is, generates a discharge control signal Sc. Thereby, the object 100 to be weighed in the weighing hopper 14 is discharged from the weighing hopper 14.

  Then, the CPU 32 proceeds to step S63 and determines whether or not the flag F5 is F5 = 1. The flag F5 is an index indicating whether or not the discharge of the object 100 in the weighing hopper 14 has been completed, and this is also managed by an interrupt task. For example, when the discharge end flag F5 is F5 = 1, this means that the discharge of the object 100 in the weighing hopper 14 has ended, and when the flag F5 is F5 = 0, the object to be measured This means that 100 discharges are not completed. This step S63 is continued until the discharge end flag F5 becomes F5 = 1, that is, until the discharge of the object 100 in the weighing hopper 14 is completed. When the discharge of the object 100 is completed, the CPU 32 proceeds from step S63 to step S65, and controls the cylinder 38 to close the discharge gate 54.

  After executing step S65, the CPU 32 proceeds to step S67 and determines whether or not the flag F6 is F6 = 1. The flag F6 is an index indicating that the discharge gate 54 is completely closed, in other words, a series (one time) of quantitative supply is completed, and this is also managed by the interrupt task. For example, when the one batch end flag F6 is F6 = 1, this means that a series of quantitative supply has ended, and when the flag F6 is F6 = 0, it means that the quantitative supply has not ended. Represent. This step S67 is continued until the one-batch end flag F6 becomes F6 = 1, that is, until a series of quantitative supply ends. Then, when the series of quantitative supply ends, the CPU 32 proceeds from step S67 to step S69.

  In step S69, the CPU 32 sets 0 to all the flags F1, F2, F3, F4, F5 and F6. Then, the process proceeds to step S71, and it is determined whether or not an automatic operation OFF command has been input (or input) by operating the operation key 42. In this step S71, for example, when an instruction for turning off the automatic operation is not input, the CPU 32 returns to step S5 in FIG. 10 to start the next quantitative supply again. On the other hand, if an automatic operation OFF command is input, the process proceeds to step S73, and the interrupt task is terminated. Then, the CPU 32 ends this automatic driving task.

  Next, the interrupt task will be described in detail. This interrupt task is performed at the rising edge (or falling edge) of the clock pulse CLK. That is, when the rising edge of the clock pulse CLK arrives, the CPU 32 proceeds to step S101 in FIG. In step S101, it is determined whether or not the above-described one batch end flag F6 is F6 = 0, in other words, whether or not a series of quantitative supply is being performed. Here, for example, when the one-batch end flag F6 is F6 = 1, that is, when a series of quantitative supply ends, the interrupt task is temporarily ended. On the other hand, when the one batch end flag F6 is F6 = 0, that is, when a series of quantitative supply is being performed, the process proceeds from step S101 to step S103.

  In step S103, the CPU 32 determines whether or not the discharge end flag F5 is F5 = 0, in other words, whether or not the discharge of the object 100 in the weighing hopper 14 has ended. Here, for example, if the discharge end flag F5 is F5 = 0, that is, if the discharge of the weighing object 100 in the weighing hopper 14 has not yet ended, the process proceeds to step S105. Note that the case where the discharge end flag F5 is F5 = 1, that is, the case where the discharge of the object 100 in the weighing hopper 14 is ended will be described in detail later.

  In step S105, the CPU 32 determines whether or not the stabilization wait end flag F4 is F4 = 0, in other words, whether or not the stabilization wait operation has ended. Here, for example, if the stabilization waiting end flag F4 is F4 = 0, that is, if the stabilization waiting operation has not yet ended, the process proceeds to step S107. The case where the stabilization wait end flag F4 is F4 = 1, that is, the case where the stabilization wait operation is finished will be described in detail later.

  In step S <b> 107, the CPU 32 acquires the digital load detection signal Wy from the A / D conversion circuit 26 via the input / output interface circuit 30. And it progresses to step S109, performs the 1st smoothing process mentioned above with respect to the said digital load detection signal Wy, and also measures weight based on the digital load detection signal Wy after this 1st smoothing process was performed. A value Wx is obtained.

  After executing step S109, the CPU 32 proceeds to step S111 to determine whether or not the stabilization wait start flag F3 is F3 = 0, in other words, whether or not the stabilization wait operation has been started. Here, for example, when the stabilization waiting start flag F3 is F3 = 0, that is, when the stabilization waiting operation has not been started yet, the process proceeds to step S113. The case where the stabilization waiting start flag F3 is F3 = 1, that is, the case where the stabilization waiting operation is started will be described in detail later.

  In step S113, the CPU 32 determines whether or not the small supply start flag F2 is F2 = 0, in other words, whether or not the small supply stage has been entered. Here, for example, when the small supply start flag F2 is F2 = 0, that is, when the small supply stage is not yet entered, the process proceeds to step S115. On the other hand, when the small supply start flag F2 is F2 = 1, that is, when the small supply stage has already been entered, this interrupt task is once ended.

  In step S115, the CPU 32 determines whether or not the estimation start flag F1 is F1 = 0, that is, whether or not storage of the weight measurement value Wx for calculating the weight estimation value Wx ″ is started. Here, for example, when the estimation start flag F1 is F1 = 0, that is, when the storage of the weight measurement value Wx for calculating the weight estimation value Wx ″ has not started yet, the process proceeds to step S117. move on. The case where the estimation start flag F1 is F1 = 0, that is, the case where the storage of the weight measurement value Wx for calculating the weight estimation value Wx ″ is started will be described in detail later.

  In step S117, the CPU 32 determines whether or not the supply start flag F0 is F0 = 0, in other words, whether or not the supply of the weighing object 100 is started. Here, for example, if the supply start flag F0 is F0 = 0, that is, if the supply of the object to be weighed 100 has not yet started, the process proceeds to step S119. On the other hand, when the supply start flag F0 is F0 = 1, that is, when the supply of the object to be weighed 100 is started, the process proceeds to step S121, and the count value of the counter for counting the storage start waiting time Tu described above. After incrementing Cu by 1, the process proceeds to step S119.

  In step S119, the CPU 32 sets a value of 0 to an index k indicating the storage order of the weight measurement value Wx for estimation of the weight estimation value Wx ″ described above. Then, the process proceeds to step S123, where the index k is used. The specified weight measurement value Wx <k> is stored, and the interrupt task is temporarily ended.

  On the other hand, when the estimation start flag F1 is F1 = 1 in step S115 described above, that is, when the storage of the weight measurement value Wx for calculating the weight estimation value Wx ″ is started, the CPU 32 performs step S125. In step S125, the count value of the counter Cd described above is incremented by 1. Note that the count value Cd is a storage period Td of the weight measurement value Wx, in other words, as will be described below. This is used to measure the calculation period (estimation period) of the estimated weight value Wx ″.

  After executing step S125, the CPU 32 proceeds to step S127, and compares the count value Cd for measuring the estimated period Td and the integer γ related to the estimated period Td. Here, for example, when the count value Cd is equivalent to the integer γ (Cd = γ), that is, when one estimation cycle Td has elapsed, the process proceeds to step S129. On the other hand, if the count value Cd is not equivalent to the integer γ (Cd ≠ γ; actually Cd <γ), that is, if one estimation cycle Td has not yet elapsed, this interrupt task is temporarily terminated. To do.

  In step S129, the CPU 32 resets the count value Cd for the estimation period Td measurement. In step S131, the value of the index k indicating the storage order of the weight measurement value Wx for estimation is incremented by 1, and then the weight measurement value Wx <k> specified by the index k is stored. The process proceeds to step S123.

  In step S111 described above, when the stabilization wait start flag F3 is F3 = 1, that is, when the stabilization wait operation is started, the CPU 32 proceeds to step S133 in FIG. In step S133, the current weight measurement value Wx is stored in a shift register (not shown) for calculating the final weight value Wf by the second smoothing process based on the above-described equation 4. The weight measurement value Wx stored in this shift register has been subjected to the first smoothing process as described above. In addition, J weight measurement values Wx are stored in the shift register. The J weight measurement values Wx are discarded in order from the oldest one each time a new weight measurement value Wx is stored. The A similar register is used for the first smoothing process, but detailed description thereof will be omitted including illustration of steps.

  After executing step S133, the CPU 32 proceeds to step S135. In step S135, the count value of the counter Cf is incremented by 1. The count value Cf is used to measure the stable waiting time Tf, as will be described next.

  After executing step S135, the CPU 32 proceeds to step S137, and corresponds to the above-described count value Cf for measuring the stable waiting time Tf and the stable waiting time Tf (strictly, the value obtained by dividing the stable waiting time Tf by the sampling period ΔT). Compared with the count conversion value). Here, for example, when the count value Cf reaches the stable waiting time Tf (Cf ≧ Tf), that is, when the stable waiting time Ts has elapsed, the CPU 32 proceeds to step S139. On the other hand, if the count value Cs has not reached the stable waiting time Ts (Cf <Tf), that is, if the stable waiting time Ts has not yet elapsed, the interrupt task is once terminated.

  In step S139, the CPU 32 sets 1 to the stabilization wait end flag F4. In step S141, the count value Cf for measuring the stable waiting time Tf is reset, and then the interrupt task is temporarily terminated.

  If the stabilization wait end flag F4 is F4 = 1 in step S105 of FIG. 13, that is, if the stabilization wait operation is finished, the CPU 32 proceeds to step S143 of FIG. In step S143, the count value of the counter Cg described above is incremented by one. The count value Cg is used to manage the opening / closing operation of the discharge gate 54 as will be described below. Specifically, the count value Cg is used to measure the discharge time Tg and the preparation time Th.

  After execution of step S143, the CPU 32 proceeds to step S145, where the count value Cg for managing the discharge gate 54 and the discharge time Tg (strictly, the count conversion value corresponding to the value obtained by dividing the discharge time Tg by the sampling period ΔT). ). Here, for example, when the count value Cg reaches the discharge time Tg (Cg ≧ Tg), that is, when the discharge time Tg has elapsed, the CPU 32 proceeds to step S147. On the other hand, if the count value Cg has not reached the discharge time Tg (Cg <Tg), that is, if the discharge time Tg has not yet elapsed, the interrupt task is temporarily terminated.

  In step S147, the CPU 32 sets 1 to the discharge end flag F5. In step S149, the count value Cg for managing the discharge gate 54 is reset, and then the interrupt task is temporarily ended.

  Further, in step S103 in FIG. 13, if the discharge end flag F5 is F5 = 1, that is, if the discharge of the object 100 in the weighing hopper 14 is ended, the CPU 32 proceeds to step S151 in FIG. In step S151, the count value Cg for managing the discharge gate 54 is incremented by 1, and the process proceeds to step S153.

  In step S153, the CPU 32 compares the count value Cg for managing the discharge gate 54 with the preparation time Th (strictly, a count conversion value corresponding to a value obtained by dividing the preparation time Th by the sampling period ΔT). Here, for example, when the count value Cg reaches the preparation time Th (Cg ≧ Th), that is, when the preparation time Th elapses, the CPU 32 proceeds to step S155. On the other hand, if the count value Cg has not reached the preparation time Th (Cg <Th), that is, if the preparation time Th has not yet elapsed, the interrupt task is once terminated.

  In step S155, the CPU 32 sets 1 to the 1 batch end flag F6. Then, the process proceeds to step S149 described above, and after resetting the count value Cg for managing the discharge gate 54, the interrupt task is terminated.

  By operating the CPU 32 in this manner, a quantitative supply including real-time control of the gate opening degree Gx in the gradual reduction stage is realized.

  In the present embodiment, the standard weight value Ws [n] and the standard gate opening degree Gs [n] at each reference time point t [n] in the gradual decrease stage are determined based on the above-described formula 3, and as a result Although the gate opening Gx in the gradual decrease stage is controlled, the present invention is not limited to this. For example, instead of the formula 3, the following formula 14 based on the formula 2 may be applied.

<< Formula 14 >>
Gx = (G1−G2) · {(t2s−tx) / (t2s−t1s)} ^α + G2

  Separately from this, for example, based on a cubic function expressed by the following Expression 15, the standard weight value Ws [n] and the standard gate opening Gs [n] at each reference time t [n] in the gradual decrease stage. Then, the gate opening degree Gx in the gradual decrease step may be controlled.

<< Formula 15 >>
Gx = c1 · tx ³ + c2 · tx ² + c3 · tx + c4

  In Expression 15, c1, c2, c3, and c4 are all constants, and are determined so that the following four conditions are satisfied. That is, as the first condition, it is required that Gx = G1 when tx = t1s. The second condition is that the gate opening G1 when tx = t1s is the maximum value of the gate opening Gx. Further, as a third condition, it is required that Gx = G2 when tx = t2s. The fourth condition is that the gate opening G2 when tx = t2s is the minimum value of the gate opening Gx.

  According to Expression 15, the gate opening degree Gx changes in a substantially S shape with respect to the elapsed time tx. Specifically, the gate opening Gx changes so that the rate of change (| dGx / dtx |) of the gate opening Gx with respect to the elapsed time tx first increases gradually and then gradually decreases. Thereby, in particular, the change in the gate opening Gx at the second switching time t2s when switching from the gradual reduction stage to the small supply stage becomes continuous (smooth), and the weighing object 100 before and after the second switching time t2s changes. The change in the supply amount Qx is reduced. As a result, generation of vibration components at the second switching time t2s is further suppressed. This contributes to further shortening of the small supply time T3, and thus greatly contributes to further shortening of the total supply time Tw including the small supply time T3.

  Further, the weight measurement value Wx for calculating the weight estimated value Wx ″ is stored for each period of Td (= γ · ΔT) with the above-described storage start time t0s as a base point, and the weight estimated value Wx ″ is obtained. However, it is not limited to this. For example, the weight measurement value Wx may be stored starting from the supply start time of the object to be weighed 100, and the weight estimated value Wx ″ may be obtained.

  In addition, the weight measurement value Wx may be stored and the weight estimation value Wx ″ may be obtained for each sampling period ΔT instead of every period of Td described above. In view of the fact that accuracy in control of the gate opening Gx is not required compared to the stage, and that the burden on the CPU 32 is reduced, in other words, even a relatively inexpensive CPU 32 can be adopted. It is also a kind of good idea to follow the period Td as in this embodiment.

  In the present embodiment, the gate opening degree Gx is corrected and controlled based on the above equation 12, but the present invention is not limited to this. For example, instead of Expression 12, the following Expression 16 may be employed. Note that ρ in Equation 16 is a correction coefficient larger than 0 (ρ> 0).

<< Formula 16 >>
Gx [n] = Gs [n] · {1-ρ · (Wx ″ [n] −Ws [n])}

  In any case, the gate opening Gx at the gradual decrease stage may be appropriately controlled so that the estimated weight value Wx ″ at the second switching time t2s is constant.

  Further, in the present embodiment, at the first switching time t1s when the weight measurement value Wx reaches the minimum standard weight value Ws [0] equivalent to the temporary first switching weight value W1, the large supply stage gradually decreases. Although it was decided to switch, it is not restricted to this. For example, as shown in FIG. 15, at the time when the above-described estimation weight value acquisition period Tc has elapsed from the storage start time t0s, that is, at the time t0 ′s when the first estimated weight value Wx ″ <β> is obtained. In this case, since the gradual decrease time T2 is lengthened, the control range of the gate opening Gx in the gradual decrease step is widened, and the control is flexible. However, since the large supply time T1 is shortened, the total supply time Tw may be prolonged.

  Further, in this case, for example, as shown in FIG. 16, the initial weight estimated value Wx ″ <β−q> (q; 1 ≦ p <β is satisfied at time t0 ″ s earlier than the time t0 ′s described above. At this point in time t0 ″ s, the large supply stage may be switched to the gradual reduction stage opening. Specifically, q is less than {β + 1} by {β + 1−q } At the time when the weight measurement values Wx are stored, that is, at the time t0 ″ s when the period of Tc ′ (= {β−q} · Td <Tc) has elapsed from the storage start time t0s, the {β + 1−q} The first estimated weight value Wx ″ <β−q> is determined based on the weight measurement values Wx. The estimated weight value Wx ″ <β− based on the {β + 1−q} weight measurement values Wx. q> is calculated based on the above-described {β + 1} weight measurement values Wx. It is the same. Thereafter, the number of weight measurement values Wx is incremented by one, such as {β + 2-q}, {β + 3-q},..., And the second and subsequent weight estimation values Wx ”in the same manner. <Β-q + 1>, Wx ″ <β-q + 2>,... Are sequentially obtained. Then, after the time point t0's when the number of stored weight measurement values Wx reaches {β + 1}, the estimated weight value Wx ″ is obtained based on the {β + 1} weight measurement values Wx. In this case, the first estimated weight value Wx ″ <β−q>, the second estimated weight value Wx ″ <β−q + 1>, the third estimated weight value Wx ″ <β−q + 2>, etc. The estimated weight value Wx ″ deviates relatively from the true supplied weight value Wx ′. FIG. 16 shows the case where the integer β is n = 9 and the subtracted integer q is q = 3. Illustrated.

  In an extreme case, the standard weight value Ws [n] and the standard gate opening degree Gs [n] at each reference time point t [n] in the gradual reduction stage are based on the weight measurement value Wx instead of the weight estimation value Wx ″. As a result, the gate opening degree Gx in the gradual decrease step may be controlled, but in this case, the influence of the vibration component including the initial vibration component is as described above. If the vibration component is relatively small, it is also a kind of advantage to be based on this weight measurement value Wx.

  In the present embodiment, the quantitative weighing device 10 that handles the granular material 100 having high fluidity such as resin pellets and granulated sugar is exemplified, but the present invention is not limited thereto. For example, the present invention can be applied to an apparatus that handles an object to be weighed having a lower fluidity than the resin pellet or granulated sugar, an object to be weighed having viscosity, and the like. In particular, when handling a viscous object to be weighed, a configuration may be adopted in which the object to be weighed is stored by a screw feeder and supplied from a reservoir hopper to the weighing hopper.

  In addition, in the present embodiment, the weighing hopper 14 is disposed below the reservoir hopper 12, and on the basis of the output Wy of the load sensor such as the load cell 18 attached to the weighing hopper 14, the weighing hopper 14 Although the configuration in which the supplied weight value Wx of the weighing object 100 is measured has been described as an example, the configuration is not limited thereto. For example, a load sensor such as a load cell 18 is provided on the reservoir hopper 12 side, and based on the output of the load sensor, the discharged weight value of the object 100 discharged from the reservoir hopper 12 is measured. The present invention may be applied.

  Further, although the servo motor 44 is employed as means for driving the open / close gate 16, it is not limited thereto. For example, instead of the servo motor 44, a stepping motor (pulse motor) may be employed. In this case, instead of the servo amplifier circuit 36, a drive circuit for a stepping motor is used. In addition, a pulse output circuit that outputs a predetermined drive pulse under the control of the CPU 32 is provided instead of the D / A conversion circuit 34 constituting the control device 22. The rotation angle of the stepping motor is controlled by the number of drive pulses applied from the pulse output circuit to the stepping motor via the drive circuit, and thus the gate opening degree Gx is controlled. Further, the rotation speed of the stepping motor is controlled by the period of the drive pulse, and consequently the rate of time change of the gate opening degree Gx (the opening / closing operation speed of the opening / closing gate 16) is controlled. By adopting the stepping motor in this way, the potentiometer 52 as the rotation angle detecting means is not necessary, and the configuration of the entire quantitative supply device 10 is simplified. On the other hand, in order to prevent the stepping motor from stepping out, it is necessary to gradually change the rotation speed particularly at the start of driving, that is, it is necessary to appropriately devise the number and period of driving pulses. Note that a motor other than the stepping motor or a driving means other than the motor, for example, a means such as the cylinder 38 described above may be employed.

  Moreover, although the case where the to-be-measured object 100 is supplied in three steps, a gradually decreasing step as a large supply step and a medium supply step, and a small supply step has been described, the present invention is not limited to this. For example, the object to be weighed 100 may be supplied in two stages of a gradual reduction stage and a small supply stage, or the object to be weighed 100 may be supplied in four or more stages. In any case, as described above, the gate opening Gx in the gradual reduction stage is appropriately controlled so that the estimated weight value Wx ″ at the second switching time t2s, which is the starting point of the small supply stage, is constant. However, it is essential.

DESCRIPTION OF SYMBOLS 10 Fixed supply apparatus 12 Reservoir hopper 14 Weighing hopper 16 Opening / closing gate 18 Load cell 22 Control apparatus 32 CPU
44 Servo motor

Claims (4)

In a quantitative supply device that supplies an object to be weighed for a predetermined target weight value,
Supply means for supplying the object to be weighed according to a supply control signal;
Supply control means for generating the supply control signal;
An elapsed time measuring means for measuring an elapsed time from the supply start time of the measurement object by the supply means;
A weight measuring means for measuring the weight of the object to be weighed supplied by the supplying means;
Comprising
The supply stop weight value smaller than the target weight value, the target switching weight value smaller than the supply stop weight value, and the elapsed time when the weight measurement value by the weight measuring means coincides with the target switching weight value. The standard switching time that is the standard of
The supply control means includes a gradual reduction stage in which the supply amount per unit time of the object to be weighed by the supply means gradually decreases and a final stage following the gradual decrease stage, and the supply amount is at the end of the gradual decrease stage. The supply means is supplied by the supply means in a plurality of stages including a small supply stage that is a constant value that is substantially equivalent to the reference value, and the elapsed time coincides with the reference switching time in the gradual reduction stage. At the first time point, the gradual reduction stage is switched to the small supply stage, and the weight measurement value at the first time point coincides with the target switching weight value. Generating the supply control signal so that the supply of the object to be weighed by the supply means is stopped at a second time point coincident with the supply stop weight value;
A quantitative supply device characterized by A plurality of standard weight values that are smaller than the switching weight value and a plurality of reference times that are a reference for the elapsed time when the weight measurement value matches each of the plurality of standard weight values are determined in advance. And
The supply control means outputs the supply control signal so that the weight measurement value at the third time point at which the elapsed time coincides with each of the plurality of reference times in the gradual decrease step coincides with the corresponding standard weight value. Generate,
The quantitative supply device according to claim 1. The supply control means compares the weight measurement value at each third time point with the corresponding standard weight value, and supplies the supply control signal based on the comparison result by the comparison means. Control signal generating means,
The fixed-quantity supply apparatus of Claim 2. The first time from the supply start time of the weighing object to the first time point is longer than the second time from the first time point to the second time point,
The fixed-quantity supply apparatus in any one of Claim 1 thru | or 3.

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