JP4776808B2 - Mass measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mass measuring apparatus, and more particularly, to a mass measuring apparatus capable of accurately correcting a measured value with respect to a temperature change.
[0002]
[Prior art]
In mass measuring devices that can measure fine masses, including electromagnetic balance weighing devices, the temperature characteristics of load sensors such as electromagnetic parts, or the temperature characteristics of mechanisms that transmit loads to these load sensors, etc. Thus, the measured value fluctuates corresponding to the temperature change. In particular, in the electromagnetic balance type device that can constitute the most accurate mechanism as a mass measuring device, the influence of the temperature is large, and therefore, the external temperature of the device and the temperature inside the weighing device are detected, and based on the detection result. A method for correcting the measured value is adopted. Hereinafter, unless otherwise specified, an explanation will be made taking an example of an electromagnetic balance type apparatus including the embodiment.
[0003]
[Problems to be solved by the invention]
In an electromagnetic balance type mass measuring device, it is known that the measured value changes due to the temperature change such as the temperature change around the device or the heat generation of the device itself. Yes. The change in the measured value is caused by various mechanisms such as a temperature coefficient of the magnet itself or a mechanical part having a mechanical structure, specifically, a load transmission mechanism in an electromagnetic balance type weighing device, and a rubber mechanism for guiding the mechanism. This is due to slight deformation of the mechanism due to differences in the linear expansion coefficients of a large number of parts constituting the.
[0004]
Usually, the measurement value is corrected in software based on temperature data measured by a temperature sensor arranged in the vicinity of an electromagnetic part, for example, a magnet 10 (see FIG. 1) constituting a part of the electromagnetic part. (Japanese Patent Laid-Open No. 5-59253, Japanese Patent Laid-Open No. 7-982341, Japanese Patent Laid-Open No. 7-120299, etc.).
[0005]
The method of placing the temperature sensor in the electromagnetic part can make a relatively good correction during measurement in the steady state, but when the temperature change outside the measuring device is in a transitional period, it is output from the temperature sensor of the electromagnetic part Depending on the temperature data, sufficient correction cannot be performed. For this reason, what provided the temperature sensor which detects the ambient temperature of a weighing device is also proposed (Unexamined-Japanese-Patent No. 2000-39356 etc.). However, this temperature sensor merely measures the ambient temperature of the weighing device, and does not directly detect the temperature effect of the ambient temperature on the mechanism, the weighing sensor, or the like in the weighing device.
[0006]
In other words, slight deformation of the mechanism due to differences in the linear expansion coefficient of each component constituting the mechanism of the electromagnetic balance type weighing device is caused by a complicated combination of deformation of each member. After all, it is very difficult to quantitatively grasp the influence of the deformation. For this reason, the change in the measured value mainly depends on the temperature coefficient of the electromagnetic part, and the actual value is that the measured value is corrected by the detected temperature of the electromagnetic part.
[0007]
In addition, since the electromagnetic part has a large heat capacity and is often arranged at the center of the apparatus as is apparent from the configuration of FIG. 1, it is relatively unaffected by external temperature changes. Changes and changes in measurement values correspond relatively well. On the other hand, as described above, the mechanical parts such as the load transmission mechanism and the roberval mechanism having a complicated configuration are at positions where they are more easily affected by the external temperature than the electromagnetic part. Therefore, if the temperature characteristics of these mechanisms can be detected more accurately, it can be expected that the measurement value is corrected more accurately.
[0008]
[Means for Solving the Problems]
The present invention is configured based on the above, and among the components constituting each mechanism part of the mass measuring device, there is a temperature change such as a component constituting the Roverval mechanism or a beam guided and operated by this Roverval mechanism. for the component that greatly affects the metric, a member made of a material having the same thermal conductivity and heat capacity and the component, separately from these components as a reference member for temperature detection (hereinafter simply referred to as "reference member") The mass measuring device is formed and configured to detect a temperature by providing a temperature sensor for the reference member, and to correct the measurement value based on temperature data detected by the reference member.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Of the members constituting the load transmission mechanism or the global mechanism for transmitting the sample load, a member whose temperature change affects the measured value, for example, a reference member made of the same material as the connection member for transmitting the sample load to the beam side It arrange | positions in the vicinity of the said connection member. The reference member is provided with a temperature sensor, and the temperature sensor directly detects the temperature of the reference member. The measured value is corrected by the temperature data detected in this reference member.
[0010]
Next, with reference to FIG. 1 showing an example of the configuration of the present invention, the background to the configuration of the present invention will be described.
In the figure, reference numeral 1 denotes an upper auxiliary rod, 2 denotes a lower auxiliary rod arranged in parallel with the upper auxiliary rod, and one end of both auxiliary rods 1 and 2 is connected to a frame 3 that supports the whole mechanism. 5 and 5 respectively. On the other hand, a floating frame 6 is connected to the other ends of the upper and lower auxiliary rods 1 and 2 via connecting members 7 and 8 having the same configuration as described above so as to be movable up and down. The frame 3, the upper and lower auxiliary rods 1 and 2, and the floating frame 6 constitute a Roverval mechanism.
[0011]
On the other hand, an electromagnetic part is accommodated in the frame 3. This electromagnetic part is composed of a yoke 9, a magnet 10 disposed in the yoke 9, a pole piece 11 positioned at the top of the magnet 10, and a coil 12 positioned around the pole piece 11. The coil 12 is wound around a bobbin 13, and the bobbin 13 is fixed to the beam 14 and is configured to move up and down together with the beam 14. The beam 14 is connected to the frame 3 by a connecting member 15 and is configured to swing around the connecting member 15 as a fulcrum.
[0012]
In the above configuration, when a sample is placed on the weighing pan 16, the load is transmitted to the floating frame 6 and is transmitted to the beam 14 through the connection member 17 while being guided by the Roverval mechanism. Thereby, a force is applied to the beam 14 so as to rotate about the connecting member 15 as a fulcrum. This force is transmitted to the coil 12 via the bobbin 13 connected to the beam 14 and tries to displace the coil 12. This displacement is detected by the sensor S, and electric power is supplied to the coil 12 so as to cancel the displacement and balance the beam 14, and the weight of the sample is measured by measuring the amount of electricity.
[0013]
In the above configuration, among the members constituting the load transmission mechanism or the robust mechanism for transmitting the load of the sample, the connection member 17 or the connection member 15 may be considered as the temperature change affects the measurement value. In this case, if a temperature sensor is directly attached to the connecting member 17 or the connecting member 15, the temperature sensor or a cable connected to the temperature sensor adversely affects the rigidity or displacement of these connecting members.
[0014]
In the present invention, a material having the same thermal conductivity and heat capacity as the connection member 17 or the connection member 15, for example, a component made of the same material as the connection member 17 or the connection member 15 is used as a reference member that is a member dedicated to temperature detection. Separately configured, the reference member is provided, for example, in the vicinity of the connection member 17 or the connection member 15, and a temperature detection unit such as a temperature sensor is provided on the reference member to measure the temperature of the reference member. , connecting member 17 or without providing a mechanism adverse effect on the connecting member 15 thermal effect mass measurement device WM that definitive to indirectly almost accurately detected, thereby accurately correcting the weight value of the weight measurement device WM It is the mass measuring device characterized by being constituted.
[0015]
【Example】
Embodiments of the present invention will be specifically described below with reference to the drawings.
In FIG. 2, reference numeral 20 denotes a temperature detection reference member made of the same material as the connection member 15 and the connection member 17. That is, the reference member 20 has the same thermal conductivity and heat capacity as those of the connection member 15 and the connection member 17, and is configured to be thermally homogeneous with the connection member 15 and the connection member 17. Further, if the shape and size of the reference member 20 are substantially the same shape and the same size as the component that is the target of the reference member 20, the measured temperature of the reference member 20 is set to be equal to that of the connection member 15 or the connection member 17. more can be expected to more approximate the temperature.
[0016]
This reference member 20 connecting member 15 and the connecting member 17, the position to equal thermal effects, more specifically, continuous space a and the connection with the space in which these connecting members 15 and the connecting member 17 is arranged In the vicinity of the member 15 and the connecting member 17, it is fixed to the frame 3 independently of these mechanisms so as not to affect the operation of the load transmission mechanism and the robust mechanism. The reference member 20 is not necessarily arranged close to the connection member 15 and the connection member 17 as long as the reference member 20 can receive the same thermal influence as the connection member 15 and the connection member 17.
[0017]
Next, reference numeral TS1 is a temperature sensor provided on the reference member 20, and the temperature data of the reference member 20 output from the temperature sensor TS1 is used as correction data for the measured value.
[0018]
Reference numeral 21 is a reference member disposed closer to the connection member 17. If the connecting member 15 and the connecting member 17 have a slight temperature difference, the reference member 21 is arranged at a position closer to the connecting member 17 even if the connecting member 17 and the arrangement space portion are continuous. If this is the case, more accurate correction can be expected. Reference numeral TS <b> 3 is a temperature sensor provided on the reference member 21.
[0019]
As described above, the present invention has been described by way of an example of an electromagnetic balance type mass measuring device. However, for example, a load cell type weighing device or the like, or a mass meter or a weight meter of another configuration, or the mass measuring device as a part of the configuration. It can be easily estimated by those skilled in the art that the present invention can be applied to an apparatus to which a mass measuring apparatus such as a moisture meter is applied.
[0020]
In each of the above embodiments, the reference member is provided on the mechanism side that transmits the load or measures the load, such as the frame 3, in any case, but the arrangement space is continuous with the connection members 15, 17 and the like. If the temperature of the connection member can be measured indirectly and accurately, the reference member is not on the mechanism unit side, but is a mechanism provided with a member for temperature measurement, such as the inner wall of the housing of the apparatus, for example. It can also be configured to be attached to another object.
[0021]
【The invention's effect】
According to the present invention, among components constituting a mechanism for transmitting a load to an electromagnetic part, for example, an electromagnetic balance type device, a member whose temperature change affects a measured value of a mass measuring device is thermally applied. Construct a reference member made of a material with equivalent properties, and place the reference member in a place where it is thermally affected by the part whose temperature is to be detected, and measure the temperature of the reference member This makes it possible to indirectly measure the temperature of a part that affects the change in the measured value without adversely affecting the load transmission mechanism, and to effectively correct the change in the measured value using this measured temperature data. It becomes.
[0022]
Further, in the present invention, the correction of the change in the measurement value is executed only as software, so there is no need to actively shut off the external temperature by installing a heat insulation structure, etc. The problem of can also be avoided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a mechanism portion of an electromagnetic balance type weighing device, showing an example of an object of the present invention.
2 is a partially broken perspective view showing a mechanism central portion of the mass measuring device WM shown in FIG. 1; FIG.
[Explanation of symbols]
3 Frame 6 Floating frame 10 Magnet 11 Pole piece 12 Coil 13 Bobbin 14 Beam 15 Connection member 17 Connection member 20 Reference member 21 Reference member TS1 Temperature sensor (for reference member 20)
TS2 Temperature sensor (for electromagnetic part)
TS3 Temperature sensor (for reference member 21)
WM mass measuring device

Claims (5)

The upper and lower auxiliary rods, the frame, and the floating frame constitute a Roverval mechanism, and a beam that swings guided by the Roverval mechanism with the connecting member as a fulcrum is provided. One end of the beam is connected to the floating frame through the connecting member. In the electromagnetic balance type mass measuring apparatus configured to transmit the load applied to the floating frame side to the electromagnetic part side by connecting the other end to the electromagnetic part, the same material as that constituting the connection member is used. A reference member is separately formed of a material having thermal conductivity and heat capacity, and the reference member is arranged at a position independent of the Roverval mechanism having these connection members and does not hinder the operation of the Roverval mechanism. Means for measuring the temperature of the reference member is provided. 2. The mass measuring device according to claim 1, wherein the connecting member is a connecting member for a beam fulcrum, and the reference member is provided on a frame of the mass measuring device in the vicinity of the beam fulcrum connecting member mounting position. . The connection member is a load transmission connection member that transmits a load to the beam side, and the reference member is provided on a frame of the mass measuring device in the vicinity of the load transmission connection member. Mass measuring device.   4. The mass measuring device according to claim 2, wherein the reference member is made of the same material as the beam fulcrum connection member or the load transmission connection member.   5. The mass measuring device according to claim 2, wherein the reference member has a shape and a size equivalent to a connection member for a fulcrum of a beam or a connection member for load transmission.

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