Displacement measurement unit and displacement measurement device using same

Abstract

To prevent problems related to implementation even when a large number of Hall sensors HSi (i=1, 2, ..., N) are required.SOLUTION: There are provided: Hall sensors HSi arranged in a direction of the length of a scale member 11; a magnet MG, which relatively moves in proximity to the scale member 11; and an electric circuit EC built in the scale member 11. The electric circuit EC includes a resistor Ri (i=1, 2, ..., N) for each Hall sensor HSi, and outputs a detection voltage V variable according to the position of the Hall sensor HSi, which operates through the magnet MG.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a displacement measuring unit that can be used to measure the amount of displacement in, for example, an automatic tension adjuster for railway overhead lines, shock absorbers for various vehicles, and the like, and to a displacement measuring device that uses the same. [Background technology]

[0002] It has been proposed to use a Hall sensor (a magnetic sensor that uses a Hall element, the same applies below) as a displacement measuring unit to be applied to a spring-type automatic tension adjusting device for railway overhead lines (for example, Patent Document 1).

[0003] Conventional displacement measurement units combine Hall sensors arranged at equal intervals on a scale member with a magnet that moves relatively close to the scale member, and select and individually supply power to each Hall sensor via a demultiplexer in order to detect the position of the Hall sensors that are activated in sequence by the movement of the magnet. That is, the Hall sensor being powered is identified by counting the control pulses supplied to the demultiplexer, and the position of the magnet can be identified and the displacement of the measurement target can be detected by detecting that the sensor being powered is currently in operation via the magnet. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-217756 A Summary of the Invention [Problem to be solved by the invention]

[0005] In such conventional technology, the Hall sensors on the scale member are selected individually in sequence via a demultiplexer and powered. Therefore, when the stroke of the displacement measurement is increased and the measurement resolution is increased so that the number of Hall sensors required is increased to, for example, 100 or more, the wiring on the narrow scale member tends to become tangled, making mounting difficult and the overall size excessive.

[0006] In view of the problems with the conventional technology, an object of the present invention is to provide a displacement measuring unit and a displacement measuring device using the same, which can keep the overall size compact and eliminate mounting problems even when a large number of Hall sensors are required by identifying an operating Hall sensor in an analog manner from changes in the detection voltage output from an electric circuit. [Means for solving the problem]

[0007] The invention of claim 1 of this application for achieving this object comprises N switch-type Hall sensors mounted at equal intervals along the length of the scale member, a magnet that moves relatively close to the scale member, and an electric circuit incorporated in the scale member, the magnet activates the Hall sensors in sequence, the electric circuit branches a power supply voltage Vo from outside the scale member to each Hall sensor, and includes a resistor Ro with a resistance value ro to one end of which the power supply voltage Vo is supplied, and a series circuit of resistors Ri (i=1, 2...N) with resistance values ​​ri (i=1, 2...N) combined with each Hall sensor, and when the nth (n≦N) Hall sensor is activated via the magnet, a detection voltage V=(ra / (ro +ra ))Vo (where ra =r1 +r2 +...+rn ) is output to the outside of the scale member. Each resistor Ri can be set to a resistance value ri=r (constant value).

[0008] The invention of claim 3 is characterized in that it comprises N switch-type Hall sensors mounted at equal intervals along the length of the scale member, a magnet that moves relatively close to the scale member, and an electric circuit incorporated in the scale member, wherein the magnet activates the Hall sensors in sequence, and the electric circuit branches off a power supply voltage Vo from outside the scale member and supplies it to each Hall sensor, and includes a selection circuit for a resistor Ro having a resistance value ro to one end of which the power supply voltage Vo is supplied, and resistors Ri (i=1, 2...N) having different resistance values ​​ri (i=1, 2...N) selected by each Hall sensor, and when the nth (n≦N) Hall sensor is activated via the magnet, a detection voltage V=(rn / (ro +rn))Vo is output to the outside of the scale member.

[0009] Moreover, the Hall sensors may be arranged in multiple rows on the scale member.

[0010] The gist of the invention of claim 5 is that it comprises a displacement measuring unit of the invention of any one of claims 1 to 4, a power supply circuit that supplies a power supply voltage Vo to the electric circuit, and a calculation unit that inputs a detection voltage V from the electric circuit via an AD converter. Effect of the Invention

[0011] According to the configuration of the invention of claim 1, the detection voltage output from the electric circuit changes according to the position of the Hall sensor operated via the magnet, so that the position of the currently operating Hall sensor can be identified by reading the detection voltage from the electric circuit from the outside, and the position of the magnet that activates the Hall sensor can be identified. That is, if a magnet is connected to a displacement member of a measurement object such as an automatic tension adjusting device of a railway overhead line, the displacement of the measurement object can be measured based on the position of the magnet. In addition, since the Hall sensors in this case do not need to be individually selected and powered, even if the required number becomes a large number, for example, more than 100, there is no problem in mounting due to tangled wiring, and a compact overall size can be easily realized.

[0012] The number of Hall sensors is N, and resistors Ri (i=1, 2, ... N) included in the electric circuit correspond to each Hall sensor. When the nth (n≦N) Hall sensor is activated, the total resistance value ra = r1 + r2 + ... + rn of the 1st to nth resistors Ri in the series circuit of resistors Ri in the electric circuit can be used as an index to identify the position of the activated Hall sensor. However, the resistance value of each resistor Ri may be ri, and each resistor Ri at this time may be set to resistance value ri = r (constant value). In addition, in the selection circuit for resistors Ri in the electric circuit, the resistance value rn of resistor Rn selected when the nth Hall sensor is activated can be used as an index to identify the position of the activated Hall sensor. However, each resistor Ri at this time has a different resistance value ri, and the same resistance value ri is not included.

[0013] Hall sensors arranged in multiple rows on a scale member can easily improve the measurement resolution because Hall sensors arranged in one row at regular intervals can be arranged in two or three rows at the same interval, which effectively reduces the spacing to 1 / 2 or 1 / 3 of the original row, respectively, thereby achieving double or triple the measurement resolution, respectively.

[0014] When configured as claimed in claim 5, the power supply circuit supplies a power supply voltage to the electric circuit, while the arithmetic unit inputs the detection voltage of the electric circuit via an AD converter, thereby identifying the Hall sensor in operation based on the detection voltage, identifying the position of the magnet, and measuring the displacement of the object to be measured, thereby achieving the effect of the invention of claim 1. [Brief description of the drawings]

[0015] [Figure 1] Schematic perspective view of the displacement measuring unit [Diagram 2] Overall electrical system diagram [Diagram 3] Equivalent circuit diagram of the electrical circuit of the displacement measurement unit [Figure 4] Schematic diagram of an example of usage [Diagram 5] FIG. 3 shows another embodiment. [Figure 6] FIG. 13 is an explanatory diagram of the arrangement of Hall sensors according to another embodiment. [Figure 7] FIG. 13 is a schematic perspective view of a displacement measuring unit according to another embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the invention will be described with reference to the drawings.

[0017] The displacement measuring unit 10 includes N Hall sensors HSi (i=1, 2 . . . N) arranged at equal intervals in the longitudinal direction of a scale member 11, and a magnet MG on a support member 12 (FIGS. 1 and 2(A)).

[0018] The scale member 11 is a narrow insulating substrate on which the Hall sensors HSi are mounted, and an electric circuit EC including a connector CT and a series circuit of resistors Ro, Ri (i=1, 2...N) is also assembled. A power supply voltage Vo from pin 1 of the connector CT is branched and supplied to each Hall sensor HSi, and the output side of each Hall sensor HSi is connected to one end of the corresponding resistor Ri. Meanwhile, one end of the resistor Ro is connected to pin 1 of the connector CT, and the connection point with the other end of the resistor R1 is drawn to pin 3 of the connector CT as a detection voltage V. The other end of the output side of each Hall sensor HSi is grounded together with pin 2 of the connector CT.

[0019] A power supply voltage Vo is supplied to the electric circuit EC on the scale member 11 from a power supply circuit 13 via pin 1 of the connector CT (FIG. 2(B)). In addition, the outputs of a battery B and a connector CV for an external power supply are input to the power supply circuit 13. A detection voltage V from the electric circuit EC is input to an arithmetic unit 15 via pin 3 of the connector CT and via an AD converter 14 as a digital signal with a predetermined number of bits.

[0020] The support member 12 for the magnet MG is disposed adjacent to the scale member 11 (FIG. 1(A)). The support member 12 moves the magnet MG relatively parallel to the scale member 11 while bringing the magnet MG close to the scale member 11 (in the direction of the white arrow pointing to the right in FIG. 1(B)), and can sequentially activate the corresponding Hall sensors HSi on the scale member 11 via the magnet MG (indicated by the downward black arrows in FIGS. 1(A) and (B)).

[0021] Therefore, if each Hall sensor HSi is, for example, a switch type that detects both poles and reacts to the magnetic flux of the magnet MG, the electric circuit EC on the scale member 11 can be rewritten as the equivalent circuit in Fig. 3. That is, in Fig. 2(A) and Fig. 3, when the nth (n≦N) Hall sensor HSn is activated, the detection voltage V=(ra / (ro+ra))Vo (where ra=r1+r2+...+rn), and the Hall sensor HSn in operation can be identified based on the detection voltage V, and the position of the magnet MG can be detected from the position of the Hall sensor HSn to measure the displacement of the support member 12. Here, ro, ri (i=1, 2...N) are the resistance values ​​of resistors Ro, Ri, and the total resistance value ra of the 1st to nth resistors Ri (i=1, 2...n) can be used as an index indicating the Hall sensor HSn in operation.

[0022] On the other hand, the power supply circuit 13 in Fig. 2(B) supplies a power supply voltage Vo to the electric circuit EC on the scale member 11. Also, the arithmetic unit 15 reads the detection voltage V from the electric circuit EC via the AD converter 14, and identifies the positions of the Hall sensors HSn and magnets MG in operation based on the detection voltage V to measure the displacement of the support member 12. Thus, the power supply circuit 13 and the arithmetic unit 15 form a displacement measuring device in combination with the displacement measuring unit 10 in Figs. 1 and 2(A).

[0023] The displacement measuring device can be applied to, for example, a spring-type automatic tension adjusting device 20 of a railway overhead wire W as a measurement target (FIG. 4(A)).

[0024] The automatic tension adjusting device 20 is configured by combining a middle tube 22 and an inner tube 23 with an outer tube 21 so that they can slide freely in the axial direction, and by incorporating compression springs (not shown) between the outer tube 21 and the middle tube 22 and between the middle tube 22 and the inner tube 23. The automatic tension adjusting device 20 is capable of absorbing expansion and contraction of the railway overhead wire W via the built-in compression springs by mounting the outer tube 21 together with the reinforcing material 21a horizontally to the support WM and connecting the railway overhead wire W to the tip of the inner tube 23.

[0025] The scale member 11 of the displacement measuring unit 10 in the displacement measuring device is fixed to the outer surface of the outer cylinder 21, and the support member 12 for the magnet MG is fixed to the tip of the inner cylinder 23. When the railway overhead wire W expands and contracts and the inner cylinder 23 is displaced in the axial direction, the Hall sensors HSi on the scale member 11 are activated in sequence via the magnet MG, and the amount of displacement of the inner cylinder 23 can be measured via the calculation unit 15 (not shown). However, in Fig. 4(A), the Hall sensors HSi are indicated by the common symbol HS.

[0026] The displacement measuring device may measure a shock absorber 30 for a vehicle, which is a combination of a hydraulic damper 31 and a compression spring 32 (FIG. 4(B)).

[0027] Annular mounting parts 31a, 31b on the cylinder side and piston side are formed on both ends of the hydraulic damper 31. A support member 12 for the magnet MG is fixed to the base of the mounting part 31b on the piston side, and the scale member 11 on which the Hall sensor HSi is mounted is held in the extension / contraction direction of the shock absorber 30 so as to be adjacent to the magnet MG.

[0028] When the shock absorber 30 expands or contracts, the Hall sensor HSi on the scale member 11 is activated via the magnet MG, and the amount of displacement of the mounting portion 31b on the piston side can be measured via the calculation unit 15 (not shown). Note that the Hall sensor HSi is also indicated by the common symbol HS in FIG. 4(B). Other embodiments

[0029] On the scale member 11, the series circuit of the resistor Ri combined with the Hall sensor HSi can be replaced with a selection circuit of the resistor Ri by the Hall sensor HSi (FIG. 5). However, FIG. 5 is an equivalent circuit of the electric circuit EC corresponding to FIG.

[0030] In Figure 5, when the nth Hall sensor HSn is activated, the detection voltage V = (rn / (ro +rn )) Vo, and the detection voltage V is determined by the resistance value rn of the resistor Rn. Therefore, based on the detection voltage V, the position of the Hall sensor HSn in operation and the position of the magnet MG can be identified and the displacement of the measurement target can be measured. However, in this case, each resistor Ri has a different resistance value ri.

[0031] The Hall sensors HSi arranged in the longitudinal direction of the scale member 11 may be arranged in a single row (FIGS. 1 and 6(A)), or in multiple rows (FIGS. 6(B) and (C)). However, in FIG. 6(A) to (C), the left-right direction of each drawing is the longitudinal direction of the scale member 11, and only a predetermined number of Hall sensors HSi are shown, starting from n=1.

[0032] Hall sensors HSi arranged in one row at intervals d in the length direction of the scale member 11 can achieve a measurement resolution equivalent to the intervals d (FIG. 6(A)). In contrast, Hall sensors HSi arranged in two or three rows at the same intervals d achieve substantial intervals of d / 2 and d / 3, respectively (FIGS. 6(B) and (C)), and can achieve high measurement resolution equivalent to intervals d / 2 and d / 3. However, when arranged in two or three rows, the Hall sensors HSi in each row are shifted in the row direction by 1 / 2 pitch and 1 / 3 pitch of the original row, respectively. The configuration of the displacement measuring unit 10 when the Hall sensors HSi are arranged in three rows on the scale member 11 is shown in FIG. 7. However, in FIG. 7, the components on the scale member 11 other than the Hall sensors HSi are omitted from the illustration. [Industrial Applicability]

[0033] The present invention can be widely and suitably applied to any measurement object including an automatic tension adjuster for railway overhead lines, which tend to be used in harsh environments, and shock absorbers for various vehicles. [Explanation of symbols]

[0034] V: Detection voltage MG…Magnet EC: Electric circuit HSi (i=1, 2…N)…Hall sensor Ri (i=1, 2…N)…Resistor 10...Displacement measurement unit 11…Scale member 13…Power circuit 14...A / D converter 15...Calculation unit Patent applicant: Linear Circuit Co., Ltd.

Claims

1. 1. A displacement measuring unit comprising: N switch-type Hall sensors mounted and arranged at equal intervals along the length of a scale member; a magnet that moves close to the scale member and relatively to the scale member; and an electric circuit incorporated in the scale member, wherein the magnet activates the Hall sensors in sequence, and the electric circuit branches off a power supply voltage Vo from outside the scale member and supplies it to each of the Hall sensors, and includes a resistor Ro of resistance value ro to one end of which the power supply voltage Vo is supplied, and a series circuit of resistors Ri (i = 1, 2 ... N) of resistance values ​​ri (i = 1, 2 ... N) combined with each of the Hall sensors, and when the nth (n ≤ N) Hall sensor is activated via the magnet, a detection voltage V = (r a / (r a +r a ))Vo (where r a =r 1 +r 2 + ... +r n ) is output to the outside of the scale member.

2. 2. The displacement measuring unit according to claim 1, wherein each of said resistors Ri is set to have a resistance value ri = r (constant value).

3. 1. A displacement measuring unit comprising: N switch-type Hall sensors mounted and arranged at equal intervals along the length of a scale member; a magnet that moves close to the scale member and relatively to the scale member; and an electric circuit incorporated in the scale member, wherein the magnet activates the Hall sensors in sequence, and the electric circuit branches off a power supply voltage Vo from outside the scale member and supplies it to each of the Hall sensors, and has a selection circuit for a resistor Ro of resistance value ro to one end of which the power supply voltage Vo is supplied, and resistors Ri (i = 1, 2 ... N) of different resistance values ​​ri (i = 1, 2 ... N) selected by each of the Hall sensors, and when the nth (n ≦ N) Hall sensor is activated via the magnet, a detection voltage V = (rn / (r o + rn )) Vo is output to the outside of the scale member.

4. 4. The displacement measuring unit according to claim 1, wherein the Hall sensors are arranged in a plurality of rows on the scale member.

5. 5. A displacement measuring device comprising: a displacement measuring unit according to claim 1; a power supply circuit for supplying a power supply voltage Vo to said electric circuit; and an arithmetic unit for inputting a detection voltage V from said electric circuit via an AD converter.

Images