JP2003098001A - Weighing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weighing device capable of shortening a warming-up time by reducing the influence of temperature unbalance to a load detector from energization start of the weighing device. SOLUTION: After start of energization of this weighing device, the heat from an electrical component 26 is transferred homogeneously to a plurality of displacement parts 31c of the load detector by a homogenizing member 33, and thereby temperature equilibrium on each displacement part 31c can be acquired quickly, to thereby shorten the warming-up time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load cell type, electromagnetic balance type, differential transformer type or tuning fork type weight checker using a strain gauge, a weighing device such as an electronic scale or an electronic balance.

[0002]

2. Description of the Related Art Generally, in a weighing device having a weighing sensor such as a load cell, if a heat source such as a motor or a power source is present near one end of the load cell, a temperature gradient occurs in the load cell, and accurate weighing cannot be performed. Therefore, in order to obtain a temperature equilibrium state, normally, after starting the energization of the weighing device,
Warming up time of about 3 to 3 hours is required.

In this case, when the weighing device is used, if another person has already turned on the power, it cannot be determined whether it is a state immediately after the power is turned on or a state in which warming up is completed. For this reason, the warm-up is insufficient and the measured value is inaccurate, or the warm-up is actually completed, and more time is wasted.

To solve this problem, there is known a device in which a thermometer is provided in a place where the temperature difference is large until the temperature of the weighing sensor is kept in the temperature equilibrium and the weighing is started when the temperature difference becomes a predetermined value or less. (Japanese Patent Publication No. 7-65922).

[0005]

However, the conventional method has the following problems. (1) Weighing can be started after confirming the temperature equilibrium, but the maximum waiting time itself does not change because it is necessary to wait until the temperature equilibrium is reached. (2) At least two temperature sensors and the like are required, and processing control means for processing the sensor output is also required, which complicates the configuration.

An object of the present invention is to provide a weighing device capable of shortening the warm-up time by reducing the influence of temperature imbalance on the load detector from the start of energization of the weighing device.

[0007]

In order to achieve the above-mentioned object, a weighing device according to one aspect of the present invention comprises a fixed end portion,
A free end portion to which a load is applied, a Roberval mechanism having a plurality of displacement portions that connect the fixed end portion and the free end portion and are displaced according to the load of the free end portion, and the displacement of the free end portion. A load detector composed of a sensor section for detecting, an electric component arranged at a different distance from at least two displacement sections of the plurality of displacement sections and generating heat by energization, and a plurality of displacement sections covering the plurality of displacement sections. The homogenizing member is made of a material having a high thermal conductivity that conducts heat generated from the components to the respective displacement parts.

According to the above construction, after the start of energization of the weighing device, the heat from the electric parts is uniformly transferred to the plurality of displacement parts of the load detector by the equalizing member, so that the temperature equilibrium between the displacement parts can be quickly obtained. .

Preferably, a plurality of the sensor portions are provided, and the plurality of sensor portions are arranged in each of the plurality of displacement portions. Therefore, the heat from the electric components is evenly transferred to the plurality of sensor parts by the equalizing member, so that the temperature balance of the sensor parts can be quickly obtained.

According to another aspect of the present invention, there is provided a weighing device including a fixed end portion, a free end portion on which a load is applied, and a plurality of sensor portions for detecting displacement of the free end portion. And a plurality of sensor parts, which are arranged at different positions from at least two sensor parts, and which cover the plurality of sensor parts and the electric parts which generate heat when energized, and conduct heat generated from the electric parts to each sensor part. And a homogenizing member made of a material having high thermal conductivity.

According to this structure, the heat from the electric parts is uniformly transferred to the plurality of sensor parts of the load detector by the equalizing member, so that temperature equilibrium between the sensor parts can be quickly obtained.
The warming-up time from the start of energization of the weighing device can be shortened.

Preferably, the partition wall is made of a material having a low thermal conductivity that prevents thermal convection between the plurality of displacement portions or the plurality of sensor portions and the place where the electric component is provided. Therefore, since the thermal conductivity of air is low, temperature incompatibility is likely to occur due to thermal convection.By installing a partition wall, the thermal convection of high temperature air is blocked and the occurrence of temperature imbalance due to thermal convection is prevented. Therefore, the warm-up time can be further shortened. Further, even when the temperature is made uniform, the temperature difference itself made uniform by the partition wall becomes small, so that the warming-up time can be further shortened.

Preferably, one end of the uniformizing member is arranged near the partition wall. Therefore, the heat transmitted to the partition wall is uniformly transmitted to the displacement portion or the sensor portion by the uniformizing member, so that the temperature equilibrium of the displacement portion or the sensor portion can be obtained faster, so that the warming-up time can be further shortened.

Preferably, the uniformizing member is a heat pipe. Therefore, by using a heat pipe having high thermal conductivity, a highly uniform effect can be obtained.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a weighing device according to a first embodiment of the present invention, and this weighing device is a weight checker for weighing the weight of an article while being conveyed by a conveyor. In FIG. 1A, a conveyor frame 11, which is a kind of conveyor device, has a conveyor frame 11 supported by a load detector 31 via an apparatus frame 29. The load detector 31 is composed of a load cell (flexure element), and a support portion 32 that supports a fixed end portion 31a of the load cell is attached to a base 40 with a bolt (not shown). The mounting bracket 29a of the device frame 29 is the load cell 31.
The weight of the apparatus frame 29 and the transport conveyor 10 is supported on the free end portion 31b of the load cell 31 as the tare weight. With this load cell 31,
The fixed end portion 31a and the free end portion 31b are connected by the beam portion 31d, and a plurality of, for example, four displacement portions 31c that are displaced according to the load of the free end portion 31b are provided between the both ends 31a, 31b and the beam portion 31d. The free-valve mechanism R and the free end portion 31b which are respectively arranged in the respective displacement portions 31c.
Sensor units 31 such as strain gauges that detect the displacement of
e (FIG. 1 (B)).
The load detector 31 subtracts the tare weight from the weight detection value including the article 50 to obtain the weight of the article 50.

A drive roller 12 is provided at one end of the conveyor frame 11, and an idle roller 13 is provided at the other end of the conveyor frame 11. A conveyor belt 15 having a flat cross section is parallel to the rollers 12 and 13. It is stretched. A motor (electrical component) 26 and a gear box 38 incorporating a bevel gear are attached to the device frame 29 via a mounting bracket 29a, and the drive roller 12 is stretched between the output pulley 37 of the gear box 38. Driven by the motor 26 via the drive belt 27,
The conveyance belt 15 is driven to convey the article 50 along the conveyance path on the conveyance belt 15.

The motors 26 are arranged at different distances from the four displacement portions 31c, and hence from the four strain gauges 31e. This motor 26 generates heat when the metering device is energized.

Mounting bracket 29a of the device frame 29
And the loredo cell 31 are provided with a heat insulator 36, and the mounting bracket 29a, the heat insulator 36, and the load cell 3 are provided.
1 and the load cell 31 are fixed to the heat insulating body 36 by the bolt B2. This insulation 36
Is made of a material having a low thermal conductivity, such as a resin material, ceramics, or stainless steel, which reduces heat conduction between the device frame 29 and the load cell 31.

As shown in FIG. 1C, the present apparatus covers the four displacement portions 31c of the load cell 31 and is made of a material having a high thermal conductivity that conducts heat generated from the motor 26 to each displacement portion 31c. A partition plate 33, which is a configured uniformizing member, is provided. The partition plate 33 is fixed to the bottom wall 29b of the device frame 29 with bolts B3. The partition plate 33 is
For example, it is formed of an aluminum plate or a copper plate. Motor 26
Since the heat from is uniformly transferred to the plurality of displacement portions 31c of the load cell 31 by the partition plate 33 via the heat insulator 36, the temperature equilibrium of each displacement portion 31c can be quickly obtained, so that the warming-up time can be shortened. Further, since the heat from the motor 26 is evenly transmitted to each sensor unit 31e, a temperature gradient is not generated, the temperature resistance of the strain gauge is made uniform, the measurable state can be reached quickly, and the warming-up time can be further shortened. Further, since the partition plate 33 is fixed to the bottom wall 29b, the heat conducted to the partition plate 33 can be released from the bottom wall 29b having a low temperature, so that the temperature rise can be reduced and the temperature difference itself can be made uniform. Becomes smaller,
The warm-up time can be further shortened.

As shown in FIGS. 1 (A) and 1 (B), this device has a thermal conductivity that prevents thermal convection between the displacement portions 31c and the sensor portions 31e and the location where the motor 26 is provided. The partition wall 35 is made of a low material. The partition wall 35 is supported so that the upper end thereof extends downward on the upper wall of the apparatus frame 29. Since air has a low thermal conductivity and temperature imbalance due to thermal convection is likely to occur, the partition wall 35 is provided above the device frame to block the thermal convection of the hot air from the motor 26 above the device frame. The occurrence of temperature imbalance due to convection can be prevented.
Further, even when the temperature is made uniform, the temperature difference itself made uniform by the partition walls 35 can be reduced, so that the warm-up time can be further shortened.

As shown in FIG. 1 (B), the partition plate 33
One end 33a of the is disposed near the partition wall 35.
Therefore, the heat transmitted to the partition wall 35 is uniformly transmitted to the respective displacement portions 31c and the respective sensor portions 31e by the partition plate 33, so that the temperature equilibrium of the respective displacement portions 31c and the respective sensor portions 31e can be obtained earlier, and the warming-up time can be further shortened. Can be shortened.

FIG. 2 is a characteristic diagram showing the time during which the temperature of the load cell 31 becomes a steady state after the start of energization of the weighing device. The solid line α represents the present device provided with the uniformizing member (partition plate) 33, the partition wall 35, and the heat insulator 36, the dashed line β represents the case where only the heat insulator 36 is provided, and the two points represent the case where neither member is provided. Shown by a chain line γ. As can be seen from FIG. 2, according to this device, the temperature rise of the load cell is suppressed, and the time tα until the temperature reaches a steady state is shorter than the time tβ when only the heat insulator 36 is provided. To be done.

As a result, the motor 26 causes the load cell 31 to move.
Even if they are arranged at different distances from the respective displacement portions 31c and the sensor portions 31e, the heat from the motor 26 is evenly distributed to the respective displacement portions 31c and the sensor portions 31e by the equalizing member (partition plate) 33 and the partition wall 35. Will be transmitted to
Since the temperature equilibrium of each displacement portion 31c and each sensor portion 31e can be quickly obtained, the warm-up time can be shortened.

Next, the second embodiment will be described.
Unlike the partition plate 33 that covers the displacement portion 31c of the load cell 31 in the first embodiment, the uniformizing member of the second embodiment uses a heat pipe having high thermal conductivity. Other configurations are the same as those in FIG. As shown in FIG. 3, in the positional relationship between the motor (left side) 26 and the load cell 31,
A heat pipe 43 extending in the left-right direction X passing through the free end portion 31b and the fixed end portion 31a of the load cell 31 is provided. The heat pipe 43 is inserted into an insertion hole 47 provided in the load cell 31 and fixed to the load cell 31. Motor 26
Even if they are arranged at different distances from the four displacement portions 31c of the load cell 31 with respect to the heat from the (left side), by using the heat pipe 43 having high thermal conductivity, a highly uniform effect can be obtained. .

FIG. 4 shows a first modification of the second embodiment. In the first modified example, unlike FIG. 3, in the arrangement in which the load cell 31 is located below the electric component 48 serving as a heat source such as a motor or a power source section, the load cell 31 has a free end 31b and a fixed end 31a. Insertion hole 47 provided
A heat pipe 43A extending in the up-and-down direction Y is inserted into and fixed to. The heat pipe 43A having high thermal conductivity even when arranged at different distances from the four displacement portions 31c of the load cell 31 with respect to heat from the electric component 48.
By using, similar to the above, a high effect of uniformization can be obtained.

FIG. 5 shows a second modification of the second embodiment. In the second modified example, unlike FIG. 3, in the arrangement in which the load cell 31 is located on the lower right side of the electric component 48 serving as a heat source such as a motor or a power source section, the free end portion 31b and the fixed end portion 31a of the load cell 31 are arranged. Between load cells 3
The heat pipes 43B that extend obliquely to each other on both side faces of the No. 1 are provided. Against the heat from the electrical components 48,
Even if they are arranged at different distances from the four displacement portions 31c of the load cell 31, by using the heat pipe 43B having high thermal conductivity, a high homogenization effect can be obtained as in the above case.

FIG. 6 shows a third modification of the second embodiment. In the third modified example, unlike the case of FIG.
In the positional relationship between (left side) and the load cell 31, protrusions 45 protruding outward are provided at the upper and lower portions of the free end portion 31a of the load cell 31, and the protrusions 45 are connected to the protrusions 45 in both the upper and lower sides of the load cell 31 in the lateral direction X, respectively. A long heat pipe 43c extending and short heat pipes 43D extending in the left-right direction X are provided above and below the fixed end portion 31b of the load cell 31, respectively. The heat pipe 43D is inserted into an insertion hole 47D provided in the load cell 31 and fixed to the load cell 31. The heat transfer from the motor 26 (left side) to the heat dissipating pipes 43C having a high thermal conductivity even if they are arranged at different distances from the four displacement portions 31c of the load cell 31,
By using 43D, a high homogenization effect can be obtained as in the above.

FIG. 7 is a plan view showing a fourth modification of the second embodiment. In the fourth modified example, in an arrangement in which the load cell 31 is located on the side of an electric component 48 that serves as a heat source such as a motor or a power supply unit, a heat pipe 43E extending in the front-rear direction Z at the upper and lower positions of the load cell 31. Is provided. The heat pipe 43E is inserted into the insertion hole 47E provided in the load cell 31 and fixed to the load cell 31. Even if they are arranged at different distances from the four displacement portions 31c of the load cell 31 with respect to the heat from the electric component 48, by using the heat pipe 43E having high thermal conductivity, a highly uniform effect can be obtained. .

In the second embodiment shown in FIGS. 3 to 7, by extending the heat pipe to a region having a low temperature, for example, the bottom wall 29b (FIG. 1) of the apparatus frame 29,
Since the temperature rise of the load cell 31 can be suppressed to a low level and the temperature difference itself for uniformization becomes small, the warm-up time can be further shortened.

As shown in FIG. 8, instead of the heat pipe, an intermediate portion 44 extending in the left-right direction X may be provided at the vertical center position of the flexure element. Even if the four displacement portions 31c of the load cell 31 are arranged at different distances with respect to the heat from the motor 26 (left side), by using the intermediate portion 44, the heat is efficiently transferred to the right fixed end portion 31a. As a result, the heat conduction to each of the displacement portions 31c is made uniform, and as in the above case, a high effect of uniformization can be obtained.

Although the first and second embodiments are applied to the weight checker using the weighing conveyor, they may be applied to an electronic scale or an electronic balance.

FIG. 9 shows a third embodiment. The third embodiment is an electromagnetic balance type electronic balance. This electronic scale
Two parallel springs 108 perpendicular to the vertical wall of the base 101
The bases of a and 108b are fixed (fixed ends), the frames 109 are attached to the ends (free ends) of the parallel springs 108a and 108b, and the weighing platform 110 is attached to the upper ends of the frames 9. The two parallel springs 108a and 108b constitute a Roberval mechanism R having a plurality of displacement portions that are displaced according to the load of the free end portion. Further, the magnetic force support mechanism having the yoke 112, the permanent magnet 114, and the force coil 117, and the displacement detector 1
A sensor unit is constituted by 18 and. In this case, the electric component that generates heat when energized is, for example, a power supply unit including a transformer (not shown), and the power supply unit is arranged at different distances from the plurality of displacement parts.

In this electronic scale, the homogenizing member 133A which covers a plurality of displacement parts as described above and is made of a material having a high thermal conductivity for conducting the heat generated from the power source part to each displacement part.
Since the heat from the power supply unit is evenly transferred to the plurality of displacement parts by the equalizing member 133A after the energization of the weighing device is started, the temperature equilibrium of the displacement parts can be quickly obtained.
Warming up time can be shortened.

FIG. 10 shows a fourth embodiment. This 4th
The embodiment is a differential transformer type electronic scale. This electronic scale has two parallel springs 1 perpendicular to the vertical wall of the base 121.
22a and 122b have their bases fixed (fixed ends), the parallel springs 122a and 122b have tips (free ends) of which a frame 123 is attached, and the frame 123 has an upper end to which a weighing platform 124 is attached. The two parallel springs 122a and 122b constitute a Roberval mechanism R having a plurality of displacement portions that are displaced according to the load of the free end portion. Further, a magnetic force support mechanism having a yoke 125, a container 126 containing the magnetic fluid 130, a float 129 floating in the container 126, and a permanent magnet 127, and a displacement detector 135 constitute a sensor unit. In this case, the electric component that generates heat when energized is, for example, a power supply unit including a transformer (not shown), and the power supply unit is arranged at different distances from the plurality of displacement parts.

In this electronic scale, the homogenizing member 133B made of a material having a high thermal conductivity which covers the plurality of displacement portions as described above and conducts the heat generated from the power source portion to each displacement portion.
Since the heat from the power supply unit is evenly transferred to the plurality of displacement parts by the equalizing member 133B after the energization of the weighing device is started, the temperature balance of the displacement parts can be quickly obtained.
Similarly, the warm-up time can be shortened.

FIG. 11 shows a fifth embodiment. 5th rice
The embodiment is a tuning fork type electronic scale. In this electronic scale, the base of the tuning fork 155 is fixed at a right angle to the vertical wall of the base 151 (fixed end), the frame 156 is attached to one piece 155a of the tuning fork 155, and the weighing platform 154 is attached to the upper end of the frame 156. It is installed and this tuning fork 1
55 forms a Roberval mechanism R having a plurality of displacement portions that are displaced according to the load of the free end portion. Further, the vibration detector includes a core 157 fixed near the tip of the tuning fork 155 and a coil 158 that allows the core 157 to move in and out, thereby forming a sensor unit. In this case, the electric component that generates heat when energized is, for example, a power supply unit including a transformer (not shown), and the power supply unit is arranged at different distances from the plurality of displacement parts.

In this electronic scale, the homogenizing member 133c which covers a plurality of displacement portions as described above and is made of a material having a high thermal conductivity that conducts heat generated from the power source portion to each displacement portion.
Since the heat from the power supply unit is evenly transferred to the plurality of displacement units by the uniformizing member 133c after the energization of the weighing device is started, the temperature balance of the displacement units can be quickly obtained.
Similarly, the warm-up time can be shortened.

FIG. 12 shows a sixth embodiment. This 6th
The embodiment is a weighing device including a compression type (tensile type) load cell. This load cell (load detector) includes a fixed end 175 fixed to the base 171, a free end 176 to which a load 172 is applied, and a plurality of strain gauges such as a strain gauge for detecting the displacement of the free end 176. It is composed of a sensor unit 173. In this case, an electric component that generates heat when energized is a printer or the like not shown, and this printer is arranged at different distances from the plurality of sensor units 173.

In this measuring device, the equalizing member 133D, which is made of a material having a high thermal conductivity, is provided to cover only the plurality of sensor portions 173 as described above and conduct the heat generated from the printer to each sensor portion 173. As a result, the heat from the printer is uniformized by the uniformizing member 133 after the power supply to the weighing device is started.
Since it is uniformly transmitted to the plurality of sensor units 173 by D, the temperature equilibrium of the sensor units 173 can be quickly obtained, so that the warm-up time from the start of energization of the weighing device can be shortened.

Although not included in the present invention, instead of using the uniformizing member, the electric component may be cooled by a cooling member such as a Peltier element, and between the electric component and the load detector. Alternatively, a Peltier element may be arranged at the position where the electric component side is cooled and the load detector side is warmed to quickly reach the temperature equilibrium point.

[0041]

As described above, according to the present invention, since the heat from the electric parts is evenly transferred to the plurality of displacement parts of the load detector by the equalizing member after the energization of the weighing device is started, Since the temperature equilibrium can be obtained quickly, the warm-up time can be shortened.

[Brief description of drawings]

FIG. 1 is a side view showing a weighing device according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an operation of the weighing device of FIG.

FIG. 3 is a side view showing a part of the weighing device according to the second embodiment of the present invention.

FIG. 4 is a side view showing a first modification of the second embodiment of the present invention.

FIG. 5 is a side view showing a second modification of the second embodiment of the present invention.

FIG. 6 is a side view showing a third modified example of the second embodiment of the present invention.

FIG. 7 is a plan view showing a fourth modified example of the second embodiment of the present invention.

FIG. 8 is a side view showing another example of the second embodiment of the present invention.

FIG. 9 is a configuration diagram showing a weighing device according to a third embodiment of the present invention.

FIG. 10 is a configuration diagram showing a weighing device according to a fourth embodiment of the present invention.

FIG. 11 is a barrel diagram showing a weighing device according to a fifth embodiment of the present invention.

FIG. 12 is a configuration diagram showing a weighing device according to a sixth embodiment of the present invention.

[Explanation of symbols]

26 ... Electric parts, 31 ... Load detector (load cell), 3
1a ... fixed end portion, 31b ... free end portion, 31c ... displacement portion,
31d ... Beam part, 31e ... Sensor part, 33 ... Uniformizing member, 35 ... Partition wall, 50 ... Article, R ... Roberval mechanism.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01G 7/02 G01G 7/02 11/00 11/00 Z 19/52 19/52 H 23/48 23 / 48 G01L 1/22 G01L 1/22 E (72) Inventor Masaki Nakajima 1-share company, Ishida Shiga Works F-term (Reference) 2F049 AA12 BA17 CA10

Claims (6)

[Claims] 1. A Roberval having a fixed end portion, a free end portion to which a load is applied, and a plurality of displacement portions that connect the fixed end portion and the free end portion and are displaced according to the load of the free end portion. A load detector including a mechanism and a sensor unit that detects a displacement of the free end; an electric component that is disposed at a different distance from at least two displacement units of the plurality of displacement units and that generates heat by energization; A metering device, comprising: a uniformizing member that covers the plurality of displacement portions and that conducts heat generated from the electric component to each displacement portion and that is made of a material having a high thermal conductivity. 2. The weighing device according to claim 1, wherein a plurality of the sensor units are provided, and the plurality of the sensor units are arranged in each of the plurality of displacement units. 3. A load detector including a fixed end, a free end on which a load is applied, and a plurality of sensor units for detecting displacement of the free end, and at least one of the plurality of sensor units. It is composed of an electric component which is arranged at different positions from the two sensor parts and which generates heat when energized, and a material having a high thermal conductivity which covers the plurality of sensor parts and conducts heat generated from the electric parts to each sensor part. A weighing device having a uniformizing member. 4. The material according to claim 1, which is made of a material having a low thermal conductivity that prevents thermal convection between the plurality of displacement portions or the plurality of sensor portions and the lift where the electric component is provided. Measuring device with a bulkhead. 5. The weighing device according to claim 4, wherein one end of the uniformizing member is arranged near the partition wall. 6. The method according to any one of claims 1 to 5, The metering device, wherein the uniformizing member is a heat pipe.