JPH032829Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic sample plate lifting and lowering device that is incorporated into an electric scale that frequently performs repeated measurements.

[Conventional technology]

For example, an electric scale conventionally used in a heat-drying automatic moisture meter as disclosed in JP-A-54-111889 repeatedly measures the weight of a sample being dried at certain time intervals. Automatic moisture measurement calculates this measured value to obtain the moisture content of the sample, but this conventional electric scale uses the zero point obtained by a single tare as a reference before repeating measurements. Measuring the weight. This is because the electric scale of an automatic moisture meter is installed in a closed enclosure, which cannot be opened while the sample is being dried and its moisture evaporated.

[The problem that the invention is trying to solve]

When using an electric scale for simple weighing purposes,
There is no problem at all because the tare can be removed each time, but for example, when using a heated dry moisture meter to measure the moisture content of a sample, it is necessary to repeat weight fluctuations and perform continuous measurements. As the sample dries, the standard may shift over time due to changes in the temperature of the components of the electric scale, making it impossible to expect accurate weight measurements. Correct weight measurement can always be achieved by raising and lowering the sample each time periodic weight measurements are taken and resetting the zero point each time, but it is extremely troublesome to perform this operation manually. Therefore, it is desirable to use an automatic mechanism that performs periodic lifting and lowering operations, and such a mechanism may be a motor, a solenoid, or the like. Furthermore, it is desirable that the time spent raising and lowering the sample be as short as possible in order to shorten measurement intervals and increase observation density. If a damper is not used with a solenoid, the lifting speed is rapid and will impact the scale body. This is a problem for precise weight measurements. It is desirable to reduce the speed when the sample plate contacts the scale and increase the speed when it leaves the scale.This is possible by using a motor, but the mechanism for controlling the speed becomes complicated. The cost will be high.

[Means to solve problems]

Therefore, in the present invention, a shape memory alloy is used in the lifting device. Shape memory alloys change their shape when heated, and the amount of change is easy to control, so it is easy to control the speed of raising and lowering the sample dish.

According to the present invention, a sample plate, a lifting device for lifting and lowering the sample plate, and a lifting device connected to the sample plate,
In an electric scale including a measuring device capable of measuring the weight, the elevating device has support means that can move vertically, and supports the support means so as to be relatively slidable, and according to the direction of rotation. rotating cam means for moving the strut means upward or downward; an actuating means connected to the rotating cam means and made of a shape memory alloy that changes shape when electrically heated; It is possible to obtain an electric scale characterized in that it includes an electrically energized control means.

According to a preferred embodiment of the invention, the strut means of the lifting device has at least three struts, the rotary cam means includes a disc-shaped rotary cam member, and the rotary cam member has three circumferentially extending struts. a spaced apart inclined cam surface on each of which the lower end of each post slidably rests; and an actuating means coupled to act on the rotating cam member in opposite directions. It includes a pair of coils made of shape memory alloy, and a control means is electrically connected to the coils. It is further preferable from the viewpoint of structure that the coil is in the shape of a compression coil.

[Action and effect]

A high-frequency pulsed current is usually used to heat the shape memory alloy with electricity. By appropriately determining the pulse width, the compression speed and displacement of the coil can be controlled. In the above configuration, the speed of the lifting device can be arbitrarily controlled by passing an appropriate pulse current through the shape memory alloy, and the structure can be made very simple. In a preferred embodiment, when the coil is heated by passing an electric current through it, if it is a compression coil, the shape changes in the direction of compression, so that the rotary cam member connected to the coil can be rotated in a desired direction. Thereby, the sample dish can be raised and lowered at appropriate acceleration and deceleration.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring first to FIG. 6, there is shown therein generally designated by the reference numeral 10 an electric scale which, when used in an automatic moisture meter such as that shown in FIG. , a heat source 60 , a reflector 61 , and an enclosure 63 surrounded by a windshield 62 .

The electric balance 10 includes a weighing section 14 disposed within a housing 12 and an external sample pan 18 connected to the weighing section by a column 16. As is well known, the weighing section 14 includes an amplifier 20 for amplifying an electric signal indicating the weight measured by the weighing section 14;
A control device 26 including a calculation section 22 connected to the computer and a display section 24 connected to the calculation section is connected. The amplifier 20 is also connected to a temperature sensor 28 that senses temperature changes in the weighing section 14 .

A lifting device 30 for lifting the sample dish 18 and separating it from the weighing section 14 is installed on the housing 12, and as will become clear later, this lifting device 30 is connected to an autotear lifting control section 32 connected to the calculation section 22. It is connected to.

Next, referring to FIGS. 1 to 5, the lifting device 3
0 has a base 34 mounted on the housing 12 of the electric scale 10 with a side opening 3 on the base.
A generally cylindrical box 38 having a diameter of 6 is provided. A boss 40 is provided at the center of the box 38, and a central opening 42 is provided around the boss 40.
A disk-shaped rotary cam member 44 having a shape is rotatably arranged. The rotary cam member 44 has a ledge 46 projecting outward through the opening 36 of the box 38.
One end of each of a pair of compression coils 48 made of a shape memory alloy is connected to this projection 46. The opposite end of each compression coil 48 is connected to the base 3
It is connected to a stop pin 50 on 4. These compression coils 48 are arranged to apply rotational forces in opposite directions to the rotating cam member 44. Although not shown, these compression coils 48 are incorporated into the circuit of the lift control section 32 mentioned above, and are heated by receiving a high frequency pulse current therefrom, so that they are respectively displaced in the compression direction. It's getting old. Therefore, by applying an appropriate high-frequency pulse current to the compression coils 48 of these shape memory alloys, their displacement amount and displacement speed can be controlled. Since the compression coils 48 are provided so as to act in opposite directions, it is possible to finely control the rotation amount and rotation speed of the rotary cam member 44.

The rotary cam member 44 has three circumferentially spaced inclined cam surfaces 52, as seen particularly in FIGS. is slidably mounted. Each post 54 projects outwardly through a hole 56 in the top wall of the box 38, with its upper end facing the bottom surface of the sample pan 18, as seen in FIG. Therefore, when the rotary cam member 44 rotates, the column 54 moves up and down by the cam action with the cam surface 55, and this movement is caused by the hole 53 of the box 38.
guided by. For example, as the rotary cam member 44 rotates in a counterclockwise direction as viewed in FIG. You will get zero points. Then, when the rotary cam member 44 rotates clockwise, the support column 54 descends, and the sample dish 18 also descends, and its weight is measured by the weighing section 14.

In automatic moisture meters, such zero point setting and sample weight measurement are performed periodically at intervals until the measurement is completed. For reference, FIG. 7 shows an example of a timing chart of the operation of the lifting device.

Although an example in which the shape memory alloy is formed in the shape of a compression coil has been described, the coil may be in the shape of a tension coil or may not be in the form of a coil. The compression coil may also be coupled to the rotating cam member in other ways. In short, as long as the rotation of the rotary cam member can be controlled using thermal displacement of the shape memory alloy, any arrangement and form can be adopted.

[Brief explanation of the drawing]

FIG. 1 is a top view of the lifting device according to the present invention. FIG. 2 is a side view of the lifting device of FIG. 1.
FIG. 3 is a sectional view taken along the - line in FIG. 2. FIG. 4 is a plan view of the rotary cam member shown in FIG. 3. FIG. 5 is a side view of the rotary cam member of FIG. 4. FIG. 6 is a diagram showing an electric scale using the lifting device shown in FIGS. 1 to 5. FIG. 7 is a diagram showing an example of a timing chart of the operation of the lifting device according to the present invention. FIG. 8 is a perspective view of a heat-drying type moisture meter using an electric scale. In the drawings, 10...electric scale, 14...weighing section, 18...sample plate, 30...lifting device, 44...
... Rotating cam member, 48 ... Shape memory alloy compression coil, 52 ... Cam surface, 54 ... Support column, 60 ... Heat source, 61 ... Reflection plate, 62 ... Windshield, 63 ... Enclosure.

Claims (1)

[Claims for Utility Model Registration] (1) An electric scale that includes a sample plate, a lifting device for raising and lowering the sample plate, and a measuring device connected to the sample plate and capable of measuring its weight, A column means by which the elevating device can move in the vertical direction; a rotary cam means which supports the column means in a relatively slidable manner and moves the column means upward or downward depending on the direction of rotation; characterized in that it includes actuating means coupled to the rotating cam means and made of a shape memory alloy that changes shape when electrically heated; and control means for electrically energizing the actuating means. An electric scale. (2) Utility model registration In the electric scale according to claim 1, the support means of the lifting device has at least three supports, the rotating cam means includes a disk-shaped rotating cam member, The rotary cam member has three circumferentially spaced inclined cam surfaces, each of the inclined cam surfaces has a lower end of each support column slidably mounted thereon, and the actuating means is arranged to rotate the rotational cam member. An electric scale comprising a pair of coils made of a shape memory alloy connected to the cam member so as to act in opposite directions, and the control means is electrically connected to the coils. (3) Utility model registration The electric scale according to claim 2, wherein the coil is in the shape of a compression coil.