The present invention relates to an elastic body for measuring loads and to a non-contact load-measuring device using the same. More particularly, the invention relates to an elastic body and a load-measuring device with which the precision for measuring load can be improved.
In the related art, the load cell is often used as a load-measuring device.
Referring to
Referring to
As described above, the strain gauges 10, 12, 14, 16 may be electrically connected with one another.
Referring to
When a load is applied, the strain gauges attached to the elastic body may expand or contract. Since resistance is changed according to the cross-sectional area and length of the wire, the expansion or contraction of a strain gauge alters the resistance value of the strain gauge. As the resistance values are changed, the equilibrium of the Wheatstone bridge circuit is broken.
In this way, an output value may be generated in the Wheatstone bridge of
The strain gauges may be attached with adhesive, but the adhesive may distort the rate of deformation of the elastic body, and its non-crystalline composition may cause unevenness in the mechanical properties.
Also, since the strain gauges themselves may experience changes in their deformation properties as they repeatedly undergo expansion and contraction, prolonged use may result in lower precision.
In an attempt to resolve these problems in contact-based load measuring by strain gauges, the inventors of the present application have proposed a non-contact load-measuring device in Korean registered patent No. 589228.
Referring to
Two boards 66, 68 may be included inside the load-measuring device. Referring to
The first board 66 and second board 68 may have electrical patterns formed thereon. The first board 66, as it is coupled to the fixed lower surface, is positioned immovably, whereas the second board 68, which is coupled to the lower surface of the elastic body, may have its position changed in correspondence with the deformation of the elastic body when a load is applied. When the elastic body 60 is deformed by a load, the second board 68 may move downwards.
To either the first board 66 or the second board 68, an alternating current may be provided. If, for example, an alternating current is provided to the pattern on the first board 66, an induced current may be generated in the pattern of the second board due to electromagnetic induction, when the second board is moved downwards by a load. If, for example, an alternating current is provided to the pattern on the second board 68, an induced current may be generated in the pattern of the first board 66 due to electromagnetic induction, when the second board is moved downwards by a load.
The non-contact load-measuring device disclosed in Korean registered patent No. 589228 can measure loads without contact using the induced current generated by electromagnetic induction as described above. The non-contact load-measuring device according to the related art is thus able to resolve the drawback of reduced precision in conventional strain gauges.
In this type of non-contact load-measuring device, however, the actual degree of precision still depends on the deformation of the elastic body, and when the same elastic body is used, it is difficult to further increase precision.
To resolve the problems in the related art such as those described above, an aspect of the present invention proposes a non-contact load-measuring device that can improve precision in measuring loads.
Another objective of the present invention is to provide a non-contact load-measuring device that can measure loads with a higher degree of precision compared to the amount of deformation in the elastic body, using the principle of leverage.
Other objectives of the present invention can be readily deduced by those skilled in the art from the embodiments described below.
To achieve the objectives above, an aspect of the present invention provides an elastic body for measuring a load. The elastic body includes: an elastic body base; a multiple number of slits formed in the elastic body base; and a deforming space part formed in the elastic body base. Inside the deforming space part are formed: a hinge, a first deforming part that is coupled with the hinge, and a second deforming part that is coupled with the first deforming part and the hinge and is formed with a greater length than that of the first deforming part. The first deforming part and the second deforming part are configured to undergo rotational movements about the hinge in correspondence to the load, the first deforming part configured to move downwards in correspondence to the load and the second deforming part configured to move upwards in correspondence to the load. The upward displacement of the second deforming part is used for measuring the load.
The deforming space part may be a hole formed in the elastic body base, and the hinge, the first deforming part, and the second deforming part may be formed inside the hole.
The slits may be formed in the elastic body base along a horizontal direction, and a first slit may be included that causes a deformation of the elastic body not to be provided to the hinge when the load is applied.
The slits may include a second slit that extends vertically from the first slit.
The slits may include a third slit that is separated from the second slit by a particular distance and is formed vertically on the elastic body base.
The second slit and third slit may be deformed in correspondence to the load, when the load is applied, and may define a load transferring part that transfers the load to the first deforming part.
The load transferring part may move downward in correspondence to the load and may be deformed to be perpendicular to the first deforming part.
The second slit can have rounded structures at both ends.
Indentations may be formed in portions of the second slit, the third slit, and the load transferring part defined by the second slit and the third slit.
A hole can be formed in a lower end of the third slit.
Another aspect of the present invention provides a load-measuring device that includes: an elastic body; an arm; a first board; and a second board. The elastic body includes a multiple number of slits and a deforming space part formed therein. Inside the deforming space part are formed a hinge, a first deforming part, and a second deforming part, where the first deforming part is coupled with the hinge, and the second deforming part is coupled with the first deforming part and the hinge and has a greater length than that of the first deforming part. The first deforming part and the second deforming part are configured to undergo rotational movements about the hinge in correspondence to a load, with the first deforming part configured to move downwards in correspondence to the load and the second deforming part configured to move upwards in correspondence to the load. The arm is coupled with the second deforming part of the elastic body along a lengthwise direction of the second deforming part, the first board is coupled to an end portion of the arm, and the second board is coupled to a securing element. Electrical patterns are formed on the first board and the second board, and the load is measured using an induced current generated in an electrical pattern formed on one of the first board and the second board in correspondence to a movement of the first board.
Certain aspects of the present invention make it possible to improve the precision of the non-contact load-measuring device in measuring loads, and using the principle of leverage, to obtain the measurements with a higher degree of precision compared to the amount of deformation of the elastic body.
The elastic body for measuring loads and the non-contact load-measuring device according to certain preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings.
Referring to
In
In
The first slit 702 may serve to prevent the deformation of the elastic body from being transferred below the first slit.
The second slit 704 may extend from the first slit 702 and may be formed along a generally perpendicular direction to that of the first slit 702.
The second slit 704, together with the third slit 706, may define a load transferring part 718. The third slit 706 may be separated from the second slit by a particular distance and may be formed along a vertical direction.
When the object of the load-measuring is placed, the load transferring part 718 may be deformed in correspondence to the load of the object.
The hinge 712, the first deforming part 714, and the second deforming part 716 may be formed inside the deforming space part 710. The first deforming part 714 and second deforming part 716 may be a single structure. For example, in
The deforming space part 710 may provide the space within which the second deforming part 716 may be deformed when a load is applied.
The hinge 712 may perform substantially the same role as a hinge in a lever arrangement. When a load is applied, the first deforming part 714 and second deforming part 716 may undergo rotational movements about the hinge.
Referring to
When a load is applied on the first deforming end 902, the first deforming end 902 may move downwards, while the second deforming end 904 may move upwards correspondingly. By the principle of leverage, if the first deforming end 902 moves down by Δa, then the second deforming end 904 moves up by Δb, where the ratio between Δa and Δb corresponds to the ratio between the lengths a and b. The longer b is compared to a, the greater the length of Δb compared to Δa.
In the non-contact load-measuring device illustrated in
In
Conversely, the end portion of the second deforming part 716 on the left side of the hinge 712 may move upward while rotating about the hinge.
The downward displacement of the first deforming part 714 and the upward displacement of the second deforming part 716 may vary depending on the lengths of the first deforming part 714 and the second deforming part 716.
Referring to
When a load is applied, the “f” portion of the elastic body base may move downwards and be deformed. The “e” portion, which corresponds to the load transferring part 718, may transfer the downward force caused by the application of the load to the first deforming part 714, which is coupled to the hinge 712.
The first deforming part 714 and the second deforming part 716, i.e. the “c” portion, may then undergo rotational movements about the hinge 712. The “e” portion, which corresponds to the load transferring part, may be deformed such that it is perpendicular to the first deforming part. While the “f” portion may undergo a simple downward movement when a load is applied, the “e” portion can maintain a perpendicular orientation in relation to the first deforming part as it moves downward, due to the third slit.
Referring to
Referring to
The second slit 1104 may extend vertically from the first slit 1102. Compared to the embodiment illustrated in
Together with the third slit 1106, the second slit 1104 may define a load transferring part 1118.
The third slit 1106 may be formed vertically on the elastic body base, and at the end of the third slit 1106, a hole 1130 may be formed.
When the object of which the load is being measured is placed, the load transferring part 1118 may be deformed in correspondence to the load of the object, with the amount of deformation corresponding with the load. The hole 1130 at the end of the third slit 1106 may increase the amount of deformation of the load transferring part 1118 and thereby improve precision.
An indentation 1132 may be formed in the middle of the second slit 1104, the third slit 1106, and the load transferring part, where the indentation 1132 may also increase the deformation of the load transferring part 1118 and improve precision.
The hinge 1112, the first deforming part 1114, and the second deforming part 1116 may be formed inside the deforming space part 1110. The first deforming part 1114 and the second deforming part 1116 may be a single structure, and in the example shown in
The end portion of the first deforming part 1114 may be coupled with the load transferring part 1118 and may be moved downwards when a load is applied.
The hinge 1112 may cause the first deforming part 1114 and the second deforming part 1116 to undergo rotational movements when a load is applied, similar to the embodiment illustrated in
The end portion of the second deforming part 1116, which is formed on the left of the hinge 1112, may move upwards in correspondence to the downward movement of the first deforming part 1114 because of the rotational movement. As described above, the upward displacement of the end portion of the second deforming part 1116 corresponds with the ratio between the lengths of the first deforming part 1114 and the second deforming part 1116.
Holes 1116a, 1116b can be formed in the second deforming part 1116. These holes 1116a, 1116b may be used to couple on the arm, which will be described later in more detail.
For a non-contact load-measuring device according to the related art, such as that illustrated in
With a non-contact load-measuring device based on an embodiment of the invention, however, it is possible to perform the measuring with greater precision compared to the elasticity of the elastic body, by forming several slits and the deforming space part in the elastic body and by applying the principle of leverage to the load-measuring device.
Referring to
The first board 1302 can include an electric pattern, i.e. a first pattern 1310, formed thereon, while the second board 1304 can include an electric pattern, i.e. a first pattern (not shown), formed thereon.
The arm 1300 can be coupled by way of the holes 1116a, 1116b of the second deforming part, and various coupling methods can be used.
The arm 1300 may substantially increase the length of the second deforming part 1116 and thus amplify the upward displacement caused by the downward movement of the first deforming part.
The first board 1302 may be coupled with the arm 1300. When a load is applied on the elastic body, causing the second deforming part 1116 to move upward, the arm 1300 may move upward in correspondence to the movement of the second deforming part 1116.
As the arm 1300 moves upward, the first board 1302 coupled with the arm 1300 may also move upward.
Conversely, the second board 1304 may be affixed independently of the first board 1302. According to an embodiment of the present invention, the second board 1304 can be immovably connected to a support 1320 that carries the elastic body. Thus, when a load is applied, the first board may move upward, but the second board may be kept still.
One of the first pattern 1310 of the first board 1302 and the second pattern of the second board 1304 may be provided with an alternating current, while the other may not be provided with an alternating current.
When a load is applied on the elastic body so that the first board 1302 is moved upward, an induced current may be generated in the pattern to which an alternating current is not provided. For example, if an alternating current is provided to the first pattern 1310 of the first board 1302 and no alternating current is provided to the second pattern of the second board 1304, then as the first board 1302 moves upward due to the load, an induced current is generated in the second pattern of the second board 1304. The induced current corresponds with the upward displacement of the first board.
As already described above, when using an elastic body according to an embodiment of the present invention, the deformation of the elastic body can be amplified using the principle of leverage, so that the displacement of the first board resulting from the load can also be amplified, and the load-measuring can be performed with greater precision.
Referring to
While
As described above, an alternating current may be provided to a pattern on one of the first board and the second board, while no alternating current may be provided to a pattern on the other. While
The load measurement according to an embodiment of the present invention can be achieved using either the magnitude of the induced current or the phase of the induced current. An appropriate type of pattern can be formed depending on which physical property is to be used.
In
As illustrated in
When the first board is moved as in
The second pattern on the second board where the induced current is generated may be electrically connected with a separate signal processing part.
Referring to
The signal converter part 1600 may serve to convert the induced current signal into a pre-designated format. For example, the signal converter part 1600 may perform a process of signal conversion, by converting the induced current, which is an analog signal, into a digital signal and removing noise components. The signal converter part 1600 can also perform amplification for the induced current.
The load calculating part 1602 may calculate the load of the object using the signal outputted from the signal converter part. According to an embodiment of the invention, the load calculating part 1602 can calculate the load using a microprocessor. The load calculating part 1602 may calculate the load using the magnitude and phase information of the output signal from the signal converter part. The load calculating part can calculate the load using a pre-designated calculation algorithm and, if a high level of precision is not required, can calculate the load using a lookup table.
The display part 1604 may serve to display the load calculated by the load calculating part. Various display devices can be used, such as an LCD, LED, etc.
While the present invention has been described with reference to particular embodiments, it is to be appreciated that various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the present invention, as defined by the appended claims and their equivalents.
Number | Date | Country | Kind |
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10-2008-0043582 | May 2008 | KR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/KR2009/002477 | 5/11/2009 | WO | 00 | 12/21/2010 |