JP7651089B2 - Displacement measurement unit and displacement measurement device using same - Google Patents

Description

This invention relates to a displacement measurement unit that can be used to measure the amount of displacement in, for example, automatic tension adjustment devices for railway overhead lines and shock absorbers for various vehicles, and to a displacement measurement device that uses the same.

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

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 in order to detect the position of the Hall sensors that are activated in sequence by the movement of the magnet, each Hall sensor is selected and powered individually via a demultiplexer. In other words, the Hall sensor that is being powered is identified by counting the control pulses supplied to the demultiplexer, and by detecting that the sensor that is being powered is currently operating via the magnet, the position of the magnet can be identified and the amount of displacement of the measurement target can be detected.

JP 2013-217756 A

In this conventional technology, the Hall sensors on the scale member are selected and powered sequentially and individually via a demultiplexer. Therefore, when the stroke for displacement measurement is increased and the measurement resolution is increased, requiring a large number of Hall sensors, such as 100 or more, the wiring on the narrow scale member tends to become tangled, making implementation difficult and the overall size excessive.

In view of the problems with the prior art, the object of this invention is to provide a displacement measurement unit and a displacement measurement device that uses the same, which can keep the overall size compact and eliminate mounting problems even if a large number of Hall sensors are required, by analogically identifying the Hall sensor in operation from changes in the detection voltage output from an electrical circuit.

The invention of claim 1 of this application to achieve this object comprises N switch-type Hall sensors mounted at equal intervals along the length of the scale member, a magnet that moves relative to the scale member in proximity, and an electric circuit incorporated in the scale member, the magnet sequentially activates the Hall sensors, 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 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 Hall sensor, 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. Each resistor Ri can be set to a resistance value ri = r (constant value).

The invention of claim 3 is configured to include N switch-type Hall sensors mounted at equal intervals along the length of the scale member, a magnet that moves relative to the scale member in proximity, and an electric circuit incorporated in the scale member, the magnets actuate the Hall sensors in sequence, the electric circuit branches the power supply voltage Vo from outside the scale member to each Hall sensor, and includes a resistor Ro with resistance value ro, one end of which is supplied with the power supply voltage Vo, and a selection circuit for resistors Ri (i = 1, 2 ... N) with different resistance values ri (i = 1, 2 ... N) for each Hall sensor, and when the nth (n ≤ N) Hall sensor is actuated via the magnet, a detection voltage V = (rn / (ro + rn)) Vo is output to the outside of the scale member.

The Hall sensors may also be arranged in multiple rows on the scale member.

The gist of the invention of claim 5 is that it comprises a displacement measurement unit according to 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 the detection voltage V from the electric circuit via an AD converter.

In the configuration of the invention of claim 1, the detection voltage output from the electric circuit changes depending on the position of the Hall sensor that is activated via the magnet, so by reading the detection voltage from the electric circuit from the outside, the position of the currently activated Hall sensor can be identified, and the position of the magnet that is activating that Hall sensor can be identified. In other words, if a magnet is connected to a displacement member of the measurement object, such as an automatic tension adjustment device for railway overhead lines, the amount of 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 is a large number, such as 100 or more, there is no problem with mounting due to tangled wiring, and a compact overall size can be easily achieved.

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 Hall sensor in operation. 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 resistor 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 Hall sensor in operation. However, each resistor Ri at this time has a different resistance value ri, and no resistors with the same resistance value ri are included.

Hall sensors arranged in multiple rows on a scale member can easily improve measurement resolution. By arranging Hall sensors in one row at regular intervals, for example, in two or three rows at the same interval, it is possible to achieve essentially 1/2 or 1/3 the spacing of the original row, respectively, thereby achieving two or three times the measurement resolution, respectively.

When the invention of claim 5 is configured, 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, and can identify the Hall sensor in operation based on the detection voltage, identify the position of the magnet, and measure the amount of displacement of the measurement object, thereby achieving the effect of the invention of claim 1.

Schematic perspective view of the displacement measuring unit Overall electrical system diagram Equivalent circuit diagram of the electrical circuit of the displacement measurement unit Schematic diagram of an example of usage FIG. 3 shows another embodiment. FIG. 13 is an explanatory diagram of the arrangement of Hall sensors according to another embodiment of the present invention; FIG. 13 is a schematic perspective view of a displacement measuring unit according to another embodiment of the present invention;

The following describes an embodiment of the invention with reference to the drawings.

The displacement measurement unit 10 comprises N Hall sensors HSi (i = 1, 2...N) arranged at equal intervals along the length of the scale member 11, and a magnet MG on the support member 12 (Figures 1 and 2 (A)).

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 built. 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 the 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.

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

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 it close to the scale member 11 (in the direction of the white arrow pointing to the right in Fig. 1(B)), and through the magnet MG, the corresponding Hall sensors HSi on the scale member 11 can be activated in sequence (downward black arrows in Figs. 1(A) and (B)).

If each Hall sensor HSi is, for example, a switch type that detects both poles and responds 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 Figure 3. That is, in Figures 2(A) and 3, when the nth (n≦N) Hall sensor HSn is activated, the detection voltage V = (r a /(r o +r a )) Vo (where r a =r 1 +r 2 +...+r n ), 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, r o , r i (i = 1, 2...N) are the resistance values of resistors R o and R i , and the total resistance value r a of the 1st to nth resistors R i (i = 1, 2...n) can be used as an index indicating the Hall sensor HSn in operation.

Meanwhile, 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. The arithmetic unit 15 reads the detection voltage V from the electric circuit EC via the AD converter 14, and measures the displacement of the support member 12 by identifying the positions of the Hall sensors HSn and magnets MG in operation based on the detection voltage V. Therefore, the power supply circuit 13 and the arithmetic unit 15 form a displacement measurement device in combination with the displacement measurement unit 10 in Figs. 1 and 2(A).

The displacement measuring device can be applied to, for example, a spring-type automatic tension adjustment device 20 of a railway overhead line W as a measurement target (Figure 4 (A)).

The automatic tension adjustment 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 adjustment device 20 is capable of absorbing the 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.

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 wire W expands and contracts and the inner cylinder 23 displaces 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 with the common symbol HS.

The displacement measuring device may measure a shock absorber 30 for a vehicle, which combines a hydraulic damper 31 and a compression spring 32 (Figure 4 (B)).

The hydraulic damper 31 has annular mounting parts 31a and 31b on the cylinder side and piston side at both ends. 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 carrying the Hall sensor HSi is held in the extension/contraction direction of the shock absorber 30 so as to be close to the magnet MG.

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 part 31b on the piston side can be measured via the calculation unit 15 (not shown). Note that in FIG. 4(B), the Hall sensor HSi is also indicated with the common symbol HS.

Other embodiments

On the scale member 11, the series circuit of resistor Ri combined with Hall sensor HSi can be replaced with a selection circuit of resistor Ri by Hall sensor HSi (Figure 5). However, Figure 5 is an equivalent circuit of the electric circuit EC corresponding to Figure 3.

In FIG. 5, when the nth Hall sensor HSn is activated, the detection voltage V = (rn / (r o +r n )) 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.

The Hall sensors HSi arranged in the length direction of the scale member 11 may be arranged in a single row (Fig. 1, Fig. 6(A)), or in multiple rows (Fig. 6(B), (C)). However, in Fig. 6(A) to (C), the left-right direction of each figure is the length direction of the scale member 11, and only a certain number of Hall sensors HSi are shown, starting with n=1.

Hall sensors HSi arranged in one row at intervals d along the length of the scale member 11 can achieve a measurement resolution equivalent to the interval d (Fig. 6(A)). In contrast, Hall sensors HSi arranged in two or three rows at the same interval d can achieve substantial intervals of d/2 or d/3, respectively (Figs. 6(B) and (C)), and can achieve a high measurement resolution equivalent to the intervals d/2 or 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 or 1/3 pitch, respectively, of the original row. The form of the displacement measurement unit 10 when 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.

This invention can be widely and effectively applied to any measurement target, including automatic tension adjustment devices for railway overhead lines, which tend to be used in harsh environments, and shock absorbers for various vehicles.

V: detection voltage MG: magnet EC: electric circuit HSi (i=1, 2...N): Hall sensor Ri (i=1, 2...N): resistor 10: displacement measuring unit 11: scale member 13: power supply circuit 14: AD converter 15: calculation unit

Patent applicant: Linear Circuit Co., Ltd.

Claims (5)

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. 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) . 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 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 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. A displacement measurement unit according to any one of claims 1 to 3, characterized in that the Hall sensors are arranged in multiple rows on the scale member. 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 the electric circuit; and an arithmetic unit for inputting a detection voltage V from the electric circuit via an AD converter.

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