JPH02150701A - Piston position detecting device - Google Patents

Abstract

PURPOSE:To detect the position of a piston from two waves of modulated signals by inserting a piston coupling section alternately provided with magnetic and nonmagnetic annular bodies on its outer peripheral surface into a primary coil for excitation and two sets of detection coils for leading out signals. CONSTITUTION:Magnetic sections N1, N2...Nn and nonmagnetic sections P1, P2...Pn are alternately arranged on the outer peripheral surface of a piston coupling member 20 at the same width (l). A primary coil 44 for excitation which inputs high-frequency signals S1 and the 1st and 2nd detection coils 46 and 48 which are arranged on the same circle center with the coil 44 in between are arranged in a metallic box body 42 and the member 20 is inserted into the box body 42. Then signals S2 and S5 produced as a result of the reciprocating motions m1 and -m0 of the member 20 are inputted to a signal processing system 14 from the coils 46, 48 and two waves of modulated signals forming a envelope signal section having a phase difference of 90 deg. are lead out. Thus the position of a piston can be detected with a simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a piston position detection device, in particular:
A piston connecting member that is connected to a piston that slides inside a cylinder tube and in which magnetic and non-magnetic materials of the same width are arranged alternately, and an excitation member that is supplied with a high frequency signal.
In a signal detector consisting of a secondary coil and two sets of detection coils arranged in an electromagnetic induction state, the secondary coil The present invention relates to a piston position detection device capable of detecting a piston position within a cylinder tube based on signals derived from a set of detection coils.

[Background of the Invention] In general, in robots for assembly processes that employ fluid pressure cylinders, the position of the piston that slides inside the tube that constitutes the fluid pressure cylinder is changed as the workpieces are transported in the order of the steps. It is necessary to check whether or not it exists in a predetermined position. In order to confirm this conformity, a detection means is employed that derives a detection signal or the like corresponding to the position of the piston within the cylinder tube. In this case, the compatible state of the piston position is displayed using a detection signal derived from the detection means. On the other hand, feedback control is performed using the derived detection signal to finely adjust the piston position to an appropriate state.

As a result of recent advances in precision assembly processes, relatively high precision has been required for the detection means employed in these devices, and as a result, light emitting/receiving elements, magnetoresistive elements, saturable cores, and the like have come to be used.

In a displacement sensor using a light emitting/receiving element, strong light from the outside causes an adverse effect, and the detecting ability of the emitting/receiving element deteriorates over time due to adhesion of dust and the like. Furthermore, displacement sensors that utilize magnets and magnetic sensing elements have their own disadvantages, such as a decrease in magnetic force over time.

[Object of the Invention] The present invention has been made in order to overcome the above-mentioned disadvantages, and the present invention has been made in order to overcome the above-mentioned disadvantages. A signal including piston connecting members arranged alternately, a primary coil for excitation into which a high frequency signal is input, and two sets of detection coils for deriving signals that sandwich the primary coil and take an electromagnetic induction state. A primary coil and two sets of detection coils are inserted into the piston connection member, and a 90” phase difference envelope signal portion is transmitted from the two sets of detection coils during reciprocating movement of the piston connection member. The formed high frequency signal (hereinafter referred to as a two-wave modulation signal) is derived, a sine wave and a cosine wave signal are extracted from the derived two-wave modulation signal, and the piston is extracted from the sine wave and cosine wave signal. It is configured to generate a position detection signal indicating the piston position as the connecting member reciprocates, and has a relatively simple configuration and does not require a contact member to detect movement, thereby avoiding wear of the member. It also acts relatively favorably against disturbances such as light, magnetic fields, and vibrations.
A further object of the present invention is to provide a piston position detection device that can effectively prevent deterioration in detection ability over time.

[Means for Achieving the Object] In order to achieve the above object, the present invention includes a cylinder and a magnetic and non-magnetic annular ring having the same width and connected to a piston that slides on the inner peripheral surface of the cylinder. A piston connecting member whose bodies are arranged alternately on an outer peripheral surface, at least one primary coil for excitation that is inserted through the piston connecting member and to which a high frequency signal is supplied, and an electromagnetic induction state of the primary coil. and is inserted into the piston connecting member and near one surface of the primary coil so as to transmit a first signal in which a sinusoidal envelope signal portion is generated upon movement of the piston connecting member. At least one or more first detection coils are disposed and are in an electromagnetic induction state with the primary coil, and are inserted into the piston connecting member, and when the piston connecting member moves, an envelope signal portion of a cosine wave is generated. A carrier wave signal is supplied to at least one or more second detection coils disposed near the other surface of the primary coil so as to send out the generated second signal, and to the excitation primary coil. a high frequency signal generating means for causing the
It is characterized by comprising movement and amount detection signal generation means for deriving a detection signal indicating the movement l of the piston connecting member from the sine wave signal and cosine wave signal drawn from the first signal and the second signal. shall be.

[Embodiment] Next, a preferred embodiment of the piston position detection device according to the present invention will be described in detail below with reference to the attached drawings. In the drawings, common components are given common reference numerals and redundant explanations will be omitted in order to avoid clutter in the text.

FIG. 1 shows a piston position detection device according to the present invention, which includes a cylinder 12 and a signal processing system 1.
It is roughly composed of 4.

The cylinder 12 includes a cylinder tube 16 that is a metal cylindrical tube, a piston 18 that slides on the inner circumferential surface of the cylinder tube 16, and a piston connecting member 20 that has one end fixed to the piston 18. The outer peripheral surface of the piston connecting member 20 has a magnetic material portion (N+
, N2, N:l...Nn) and the non-magnetic part (P +
, P2, P3 .''P-) are alternately arranged with the same width β.

The piston 18 is provided to slide within the cylinder tube 16 with seal members 22 and 23 interposed therebetween. Furthermore, one end 2Of of a piston connecting member 20 is passed through the piston 18, and is firmly tightened with screw members 24a and 2.4b.

One end 16r of the cylinder tube 16 is fitted onto the lid 28 up to a predetermined position. On the other hand, cylinder tube 1
The other end 16β of 6 is externally fitted and fixed to the lid 30 up to a predetermined position, and furthermore, the piston connecting member 20 is axially passed through the center opening 30a.

The lids 28 and 30 have screw members 32a and 32b.
Further, the cylinder tube 16 is firmly fixed by a similar screw member (not shown), and the inside of the cylinder tube 16 is maintained in a sealed state. The direction m1- of the piston connecting member 20 is inside the lid body 30.
A signal detection unit 40 is provided to obtain a detection signal accompanying the reciprocating movement of Tl1o. As can be understood from the figure, in the signal detection section 40, the piston connecting member 20 is inserted into a metal frame 42 that also serves as a shield, and a high frequency signal SI is input to the piston connecting member 20. The primary coil 44 for excitation and the primary coil 4
A first sensing coil 46 and a second sensing coil 48, which are arranged with the center line of the center line being the same, are axially passed through. In this case, the primary coil 44, the first detection coil 46,
The second detection coils 48 are each mounted on a bobbin member (not shown) with the loop wires wound in a unified direction, for example, in a right-handed manner, and are fixed in the frame body 42 via an attachment member (not shown). has been done. Then, the first detection coil 46 and the second detection coil 48 send out detection signals S2 and Ss generated during the reciprocating movement of the piston connecting member 20 in the direction mi-mo, and these detection signals S2 and S5 are processed by signal processing. It is input to system 14.

Further, the lid 28 and the lid 30 are provided with ports 50 and 52 for supplying and discharging fluid.

It is understood that with the above configuration, as the piston 18 reciprocates in the direction m1-mo, the head 20h of the piston connecting member 20 can reciprocate in the VI Vo directions shown in the figure in response. It will be. The head 20h of the piston connecting member 200 is attached to a mechanical part that serves as a drive means for various devices (not shown), thereby forming a reciprocating drive means, a rotation means, etc., and serves the desired purpose. . Then, the direction mi of this piston 18
-mo reciprocation to ports 50 and 52, e.g.
This is achieved by intermittently sucking and exhausting compressed air into the first chamber SP and the second chambers S and 2.

Here, the configuration of the signal processing system 14 will be explained. FIG. 2 shows the configuration of main blocks of the signal processing system 14.

The signal processing system 14 includes an oscillation means 56 that oscillates a high frequency signal S of carrier wave of 100 KI (z) and applies it to the primary coil 44. A rectifier circuit 58 into which the signal S2 is input, and a rectified signal S half-wave rectified by the rectifier circuit 58.
, and is provided with a DC amplifier 60 that sends out an amplified signal S6 amplified to a predetermined value. Furthermore, a rectifier circuit 62 to which the detection signal S derived from the second detection coil 48 is input, and a rectification signal S7 that has been half-wave rectified in the rectifier circuit 62 are supplied, and the amplified signal S is amplified to a predetermined value. ,
It has a DC amplifier 64 that sends out. It also includes a phase division circuit 66 to which the amplified signals S6 and S are respectively supplied. The phase division circuit 66 also includes an output terminal 68 from which an output signal SIO is derived.

Next, the piston connecting member 20 will be explained in detail with reference to FIG. This piston connecting member 20 is made of, for example, 345C (carbon steel), as can be understood from FIG. 3A, and has magnetic parts (Nl, N2, N3"
'N, ) and non-magnetic parts (P+, P2, Ps...
・P, ) are arranged alternately with the same width l.

The magnetic part is made of 345C material, and the non-magnetic part is formed by the following method. First, a portion of the surface layer of the material where the non-magnetic material portion will be formed is removed to a predetermined depth, and grooves are formed alternately. Next, non-magnetic chrome plating is applied to fill the grooves and polish the surface. In this way, a piston connecting member 20 is created in which magnetic parts (NI, N2, N3...N, , ) and non-magnetic parts (p, , P2, P3...P,) are alternately formed. be done. As the next example, in the example shown in FIG. 3, the surface of a member such as a 345C round bar is first subjected to, for example, a coating lamination process, and then a magnetic plating process, such as a chrome plating process, is applied. Furthermore, the plating layer is removed by performing etching treatment alternately with a width β. Furthermore, a nonmagnetic chrome plating process is performed to fill in the grooves removed by the etching, and finally, the surface is polished. In this way, a piston connecting member 20 is created in which magnetic portions (NI, N2, N3...Nh) and non-magnetic portions (Pr, P2, P3''P,) are alternately formed.

Next, with reference to FIG.
N2, N3...N, ) and the non-magnetic part (P, , P
2, P3...P,) will be explained in detail.

Primary coil 44 and first sensing coil 46 inside frame 42
The width d (thickness) of the second sensing coil 48 is formed between the width l of the magnetic material portion and the non-magnetic material portion. The first sensing coil 46 is arranged so that the center line a when the thickness is divided is the same as the center line a when the width l of the non-magnetic part P2 is divided. Further, the second sensing coil 48 is arranged so that its center line in its thickness is as close as possible to the junction line between the non-magnetic portion P and the magnetic portion N3. The first
A primary coil 44 is attached between the detection coil 46 and the second detection coil 48. By being arranged in this way, the first sensing coil 46 and the second sensing coil 48 are connected to the magnetic body part (NI
, N2, N, . . . N,), the signal with the maximum value is derived. Also, non-magnetic parts (P+, P2, P3
. Furthermore, the first and second sensing coils 46
The signal derived from 48 and 48 includes a 90° phase difference signal, that is, is sent out as a two-wave modulated signal.

The piston position detection device according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

The first chamber SP and the second chamber S in the cylinder tube 16
.

Then, the oscillating means 56 supplies the primary coil 44 with, for example, 1
A high frequency signal S1 for excitation of 00 KHz is applied. As a result, the first and second sensing coils 46 and 48 generate a voltage (hereinafter referred to as induced voltage) induced by electromagnetic induction at the same frequency as the high frequency signal SI. The induced voltages are derived as detection signals S2 and S5, respectively.

In a state where such an induced voltage is generated in the first and second sensing coils 46 and 48, the piston connecting member 2
0 is reciprocated in the direction mi-mo, the magnetic body portion (NI SN
2, N5-N-) and the non-magnetic part (P, , P2, P3.
. . P, , ), the magnetic permeability changes, and as shown in FIG. 5, detection signals S2 and S5 are derived in which the carrier wave of the high-frequency signal S1 is modulated in accordance with its movement. be done. A phase difference of 90° is formed between the sine wave envelope portion 82N and the cosine wave envelope portion SSX formed in the detection signals S2 and S5. Next, the detection signal S2
is rectified by the rectifier circuit 58, and as shown in FIG. 5, a rectified signal S of the sine wave envelope portion S2X is extracted. The rectified signal S is amplified to a predetermined value by a DC amplifier 60, and a sinusoidal amplified signal S6 is derived as shown in FIG. 5C.

On the other hand, the detection signal S5 is similarly rectified by the rectifier circuit 62, and as shown in FIG.
A rectified signal S7 of M is extracted.

The rectified signal S7 is amplified to a predetermined value by the DC amplifier 64, and as shown in FIG.
, is derived.

The thus derived sine wave and cosine wave amplified signals S6 and S9 are supplied to a phase division circuit 66, respectively. Here, sine wave and cosine wave amplified signals S6 and S
9 is divided into equal parts, a corresponding pulse signal is generated, and the generated pulse signal is outputted to the output terminal 68. The output signal SIO formed into the pulse signal is, for example, in a counter,
The number of pulses is counted on the time axis to calculate the absolute amount of movement of the piston connecting member 20 with respect to the signal detection unit 40.

Next, modified examples of the signal detection section will be explained using FIGS. 6 to 8.

In both of these modified examples, two sets of signal detection sections corresponding to the signal detection section 40 are used. The purpose of this is to increase the output level of the detection signals S2 and S5.

In FIG. 6, the primary coil 8 is composed of a first detection section 70 and a second detection section 75, and is housed in a frame 78 that also serves as a shield.
0, and first and second sensing coils 82 and 84 having the same circular center line with the primary coil 80 in between. On the other hand, the second detection unit 75 also uses the primary coil 90 in the same manner.
, first and second sensing coils 92 and 94.

Here, the magnetic material portion (N
, , N2, N5-N,) and the non-magnetic part (P, ,
P2, P.

...Ph), the primary coil 80.90, the first detection coils 82 and 92, and the second detection coils 84 and 94.

In this case, each of the coils is formed with the same width d, and the magnetic material portion (No, N2
, N3...N, ) and the non-magnetic part (P+ , P2 ,
P3...P,,) are arranged.

The first sensing coil 82 and the non-magnetic portion P2 have the same centerline C, and the second sensing coil 84 and the magnetic portion N have the same centerline e. Furthermore, the center line f of the first sensing coil 92 is arranged on the same line as the joining line between the non-magnetic part P5 and the magnetic part N8. The center line g of the second detection coil 94 is between the magnetic part N4 and the non-magnetic part P4.
It is located on the same line as the joining line. With this arrangement, first, the high frequency signal S1 is supplied from the oscillating means 56 to the primary coils 80 and 90, and the piston connecting member 2° is caused to reciprocate in the directions m and mo. As a result, the first and second detection coils 92 and 94 derive detection signals in which the carrier wave of the high-frequency signal S1 is modulated. The detection signal includes substantially sine wave and cosine wave signals having a phase difference of 90° between the envelope portions formed. However, the detection signals of the first detection coil 82 and the second detection coil 84 have opposite phases. Therefore, as shown in the figure, the connection wires of the second sensing coil 84 are connected in reverse in advance. Note that the first detection coil 92
The same applies to the second detection coil 94.

Therefore, the obtained detection signal S2b is
and the detection signal of the second detection coil 84, that is, the signal value is obtained by superimposing and adding the induced voltage with the same phase. Similarly, the detection signal Sob has a signal value obtained by superimposing and adding the induced voltages of the first detection coil 92 and the second detection coil 94 with the same phase.

This configuration is advantageous, for example, when remote control is employed and the detection signals S2b and SSb are sent to a relatively remote location, that is, when transmission loss is relatively large.

Further, in FIG. 7, the first detection coil 82 and the second detection coil 84 are in the same phase, and the first detection coil 92
and the second detection coil 94 are also in the same phase.

Furthermore, in the example of FIG.
The width l of a and 94a is made larger than that shown in FIGS. 4, 6 and 7, and this is an example of a configuration in which the output voltage is increased and derived, for example. The respective functions in FIGS. 7 and 8 are basically the same as those in the example shown in FIG. 6, and a redundant explanation thereof will be omitted.

In the above-described example of the present invention, the cylinder tube 16 is made of a metal material, but it is not prohibited to use a plastic member or the like, or to use a tubular member instead of a rod-like member for the piston connecting member 20. . Further, the cross section of the cylinder tube 16 is not circular, for example,
It may also have a square shape.

[Effects of the Invention] As described above, according to the present invention, a piston connection is provided that is connected to a piston that slides in a cylinder tube, and in which magnetic and non-magnetic annular bodies having the same width are alternately arranged on the outer periphery. A signal detector including a member, a primary coil for excitation to which a high frequency signal is manually applied, and two sets of detection coils for deriving a signal that is in an electromagnetic induction state, sandwiching the primary coil,
A primary coil and two sets of detection coils are inserted through the piston coupling member, and envelope signal portions with a 90° phase difference are formed from the two sets of detection coils during reciprocating movement of the piston coupling member. Deriving a wave modulation signal, extracting a sine wave and a cosine wave signal from the derived two-wave modulation signal, and a position indicating the piston position as the piston connecting member reciprocates from the sine wave and cosine wave signals. The structure is configured to generate a detection signal, and as a result, the structure is relatively simple and movement detection does not require a contact member, so there is no wear of the member and it is not susceptible to external disturbances such as light, magnetic fields, vibrations, etc. This works relatively advantageously, and has the effect of effectively preventing the deterioration of detection ability over time.

Although the present invention has been described above by citing preferred embodiments, the present invention is not limited to these embodiments (
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of a piston position detection device according to the present invention, FIG. 2 is a circuit block diagram showing main parts of a signal processing system of the piston position detection device shown in FIG. 1, and FIG. 3 is a partial sectional view showing the configuration of a piston connecting member in one embodiment of the piston position detection device shown in FIG. 1, and FIG. 4 is a signal in one embodiment of the piston position detection device shown in FIG. 1. FIG. 5 is a processing waveform diagram in the signal processing system shown in FIG. 2; FIG. 6 is a cross-sectional view showing the configuration of a modified example of the signal detection section shown in FIG. 1; 7 is a sectional view showing the configuration of another modification of the signal detection unit shown in FIG. 1, and FIG. 8 is a sectional view showing the configuration of still another modification of the signal detection unit shown in FIG. 1. FIG. 12... Cylinder 16... Cylinder tube 18... Piston 20... Piston connecting member 28. 30... Lid body 40... Signal detection section 44... Primary coil for excitation 46. ...First detection coil 48...Second detection coil S, ...High frequency signal for excitation S2...Detection signal S from the first detection coil, ...Detection signal milk from the second detection coil . ...output signal
N, ~N,...Magnetic body part P1-P0...Nonmagnetic body part FIG, 6 FIG, 5

Claims (1)

[Claims] (1) A cylinder, a piston connecting member connected to a piston that slides on the inner peripheral surface of the cylinder, and in which magnetic and non-magnetic annular bodies of the same width are alternately arranged on the outer peripheral surface, and the piston connecting member. at least one primary coil for excitation that is inserted through the member and to which a high frequency signal is supplied; and a state of electromagnetic induction with the primary coil, and movement of the piston connecting member while being inserted through the piston connecting member. The first part in which a sinusoidal envelope signal part is generated at
at least one or more first sensing coils disposed near one surface of the primary coil so as to send out a signal; and at least one first sensing coil that is in an electromagnetic induction state with the primary coil and inserted into the piston connecting member. at least one coil disposed near the other surface of the primary coil so as to transmit a second signal in which a cosine wave envelope signal portion is generated upon movement of the piston connecting member. 2 detection coils;
High frequency signal generating means for supplying a carrier signal to the excitation primary coil, and detection indicating the amount of movement of the piston connecting member using a sine wave signal and a cosine wave signal extracted from the first signal and the second signal. A piston position detection device comprising a movement amount detection signal generation means for deriving a signal.