JPH01153803A - Piston position sensor - Google Patents

Abstract

PURPOSE:To eliminate the fitting adjustment of a contactless switch even if the position of a piston changes slightly by providing the first, the second and the third luminous elements which display that the position of the piston is in an allowable zone, adequate zone, and the optimum zone, respectively. CONSTITUTION:Magnetic sensors 26, 28 are arranged on the outer circumference of a cylinder 2 and output signals from the magnetic sensors 26, 28 are led via the first and second comparator 38, 42 a window comparator 40 to a red light emitting diode D2 related to the indication of an allowable operation zone, a green light emitting diode D4 related to adequate operation zone and a green light emitting diode D6 related to the optimum operation zone. Accordingly, it becomes possible to separately detect the adequate operation zone so that it becomes unnecessary to fit adjust a contactless switch again even if there is the slight change of the position of the piston.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a piston position sensing device, in particular:
A piston position detection device that detects whether or not a piston in a cylinder is reciprocating within a predetermined position range, and also detects and displays in which area within the cylinder the piston is located. Regarding.

[Background of the Invention] In general, when trying to accomplish precision work using a fluid pressure cylinder, for example, when trying to transport a workpiece to the next processing step using a fluid pressure cylinder, the piston inside the cylinder It is necessary to confirm whether the predetermined position has been reached. An example of such a case will be described below.

The cylinder 2 shown briefly in FIG. 1 has a piston 4 inside it.
Fluid pipes 6 and 8 are connected to two chambers separated by the piston 4 in a slidable manner. Note that reference symbols A to E indicate regions into which the chamber within the cylinder 2 is divided.

In this case, at a certain stage of the work process, the proper operating range is for the piston 4 to be located in area C, and even if the piston 4 is located in area B or D, it is still within the allowable operating range. It is said that However, in a predetermined work process, if the piston 4 is located in or near area A outside the allowable operating range, the intended work cannot be accomplished.

In order to improve these shortcomings, the present applicant has filed Utility Application No. 62-0.
As shown in No. 82659, a light emitting element that emits different light when the piston is in the proper area C in the cylinder and when it is in the permissible areas B and D, and an electric circuit that energizes it, is provided, Due to the difference in the emission color of the light emitting element,
We have proposed a piston position detection device that makes it easy to visually confirm from the outside whether the piston is within a proper operating range or an allowable operating range, and it has come to be widely adopted.

That is, in the piston position detection device according to the prior art, a logic gate is disposed between a magnetic sensor having a binary output of 0N10FF and a display circuit, and when the outputs of both magnetic sensors are ON, one The light emitting element provided separately from the light emitting element that operates when the magnetic sensor is ON is configured to operate.

Therefore, in the piston position detection device according to the prior art, for example, the piston is outside the left allowable movement range A in FIG.
When the piston moves to the right and reaches outside the permissible operating range, the first light emitting diode lights up to indicate that the piston is located within the left-hand permissible range B, and when the piston moves further to the right and reaches the proper operating range C. In this case, the first light emitting diode turns off, and the second light emitting diode, which emits light in a different color from the first light emitting diode, turns on.If it moves further to the right and reaches the right-side allowable operating range, the second light emitting diode turns off. , the third light emitting diode that emits light in the same color as the first light emitting diode is turned on, and if the third light emitting diode moves further to the right and goes outside the allowable operating range 13, the third light emitting diode is also turned off.

[Object of the Invention] The present invention is made in relation to the above-mentioned device, and includes:
As shown in Figure 2, the proper operating range C is divided into an optimal operating range C2 and sub-optimal operating ranges CI and C3, and different light-emitting elements or light-emitting elements with different emission colors are lit according to the divided ranges. This makes it possible to install the proximity switch within the optimum operating range C2, and in fact, even if the position of the piston 4 of the cylinder 2 changes slightly, it stays within the appropriate operating range C and the mounting position can be readjusted. The purpose of the present invention is to provide a piston position detection device that does not require the use of a piston position detection device.

[Means for Achieving the Object] In order to achieve the above object, the present invention provides a first light emitting element that indicates that the piston position within the cylinder is within the permissible range, and a first light emitting element that indicates that the piston position within the cylinder is within the permissible range. The piston position is characterized by comprising a second light emitting element that displays that the piston position is within an appropriate range, and a third light emitting element that displays that the piston position is within an optimal range within the appropriate range.

[Embodiments] Next, preferred embodiments of the piston position detection device according to the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the same components as those shown in FIG. 1 or FIG. 2 are given the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 3, a piston 4 is disposed inside the cylinder 2 and slides in the horizontal direction of the figure. Said cylinder 2
Magnetic sensors 26. having similar magnetic sensitivities are arranged on the outer peripheral surface of the piston 4 at a predetermined distance apart along the sliding direction of the piston 4.
28 are arranged, these magnetic sensors 26.28 output a signal proportional to the magnitude of the magnetic field acting from the magnet 24 arranged on the piston 4. Note that the cylinder 2 is made of a non-magnetic material that easily transmits the lines of magnetic force of the magnet 24, for example,
It is made of aluminum or the like.

Next, FIG. 4 shows a schematic circuit block diagram of a piston position detection device including the magnetic sensors 26 and 28. In the figure, the power supply terminals of the magnetic sensors 26 and 28 are connected to a power source (not shown) whose voltage is Vcc.
6.28 earth terminal is grounded. The magnetic sensor 2
The output signal of 6.28 is introduced into an amplifier 34.36.

The output signal E+ of the amplifier 34 is introduced into the input terminal of the first comparator 38 and also into the signal input terminal α of the window comparator 40. on the other hand,
The output signal E2 of the amplifier 36 is introduced into the input terminal of the second comparator 42, and is passed through an adder 44 and a subtracter 46 to the upper limit reference input terminal α of the window comparator 40. and a lower limit reference input terminal α.

In this case, the first and second comparators 38.42
A reference voltage VR obtained by dividing the power supply voltage Vcc by a variable resistor RV2 is introduced into the reference input terminal of the adder 44,
A variable resistor RV is connected to the addition or subtraction input terminal of the subtracter 46.
4. A minute voltage ΔE set by RV6 and added to the output signal E2 of the amplifier 36 is applied. Note that power supply voltages Vcc and -Vcc are applied to one end of the fixed terminals of the variable resistors RV4 and RV6, respectively, and the other end is grounded.

The output signal V1 of the first comparator 38 is output to the OR circuit 4.
8. Exclusive OR circuit 50 and AND circuit 5
2, the second comparator 42
The output signal V2 is introduced into the other input terminals of the OR circuit 48, the exclusive OR circuit 50, and the AND circuit 52. The output signal V3 of the OR circuit 48 is output from the buffer 5
4 to the base terminal of a transistor Q2 operating in an open collector type, and the emitter terminal of the transistor Q2 is grounded. Note that the collector terminal 56 of the transistor Q2 is used as a control output. Also,
The output signal V4 of the exclusive OR circuit 50 is current-amplified by a buffer 57, and then connected in series with a red light emitting diode D2 and a resistor R2 for displaying the permissible operating ranges B and D (see FIG. 1 or 2). introduced into the circuit. Further, the output signal V5 of the AND circuit 52 is passed through a buffer 58 to a series circuit of a green light emitting diode D4 and a resistor R4, which are connected to a semi-optimal operating range C1, C3 (see FIG. 2) within the above-mentioned proper operating range C. Along with being introduced to
It is introduced into one input terminal of the AND circuit 60. The output signal v6 of the window comparator 40 is introduced into the other input terminal of the AND circuit 60, and the output signal V7 of the AND circuit 60 is passed through the buffer 62 to the optimum operating range C2 (see FIG. 2). It is introduced into a series circuit consisting of a green light emitting diode D6 and a resistor R6 for display.

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.

5a to 5 schematically illustrate the positional relationship between the magnet 24 provided on the piston 4, that is, the piston 4, and the magnetic sensor 26, 28, and also show the position of the magnet 24, that is, the position of the piston 4, and the light emission. Diode D2) D4, D6
In the figure, the mesh indicates the off state and the white indicates the on state.

In the figure, a parabolic line indicates a signal E appearing in the outputs of the amplifiers 34 and 36 via the magnetic sensors 26 and 28 when the magnet 24 is at the apex position of the parabola.
1, the envelope of E2 is displayed. In this way, the magnetic sensor 26.28 outputs an analog signal depending on the strength of the magnetic field applied to the magnetic sensor 26.28. Moreover, in the figure, the dashed-dotted line indicates the reference voltage VR. In addition,
In Figures 5a to 5, the letters A, B, C+, C2, C5, D, circled below the light emitting diodes D2) D4, D6,
E corresponds to the alphabet indicating the predetermined area shown in FIG. 1 or 2.

First, as shown in FIG. 5g, if the magnet 24 is relatively far from the magnetic sensor 26.28, the magnet 24
The output signal E of the amplifier 34.36 is proportional to the output voltage generated in the magnetic sensor 26.28 by the magnetic field caused by the
E2 is below the reference voltage VR, and the light emitting diode D
2) Both D4 and D6 are off. Therefore, the piston 4 exists in region A outside the allowable operating range.

Next, when the magnet 24 at the position shown in FIG. 5g moves in the direction of arrow G due to the displacement of the piston 4, the output signal E1 caused by the magnetic sensor 26 as shown in FIG.
becomes equal to the reference voltage VR, the first comparator 38 is inverted, the OR circuit 48 and the exclusive OR circuit 50 are inverted, the transistor Q2 is energized, the red light emitting diode D2 is lit, and the piston 4 is turned on.
It is understood that this has fallen outside the permissible operating range. In this case, the second comparator 42 inputs a signal E2 to it.
Since the value of is less than the reference voltage VR, it is not inverted. Therefore, the AND circuit 52 does not operate and the green light emitting diode D4 does not light up.

Furthermore, since the window comparator 40 operates only when the absolute value IEI E2 l =ΔE+□ of the difference between the signals E1 and E2 is smaller than the minute voltage ΔE (see Fig. 5g), the green light emitting diode according to the optimum operating range C2 operates. D6 does not light up.

Next, if the magnet 24 further moves in the direction of arrow G, the fifth
As shown in Figure C, the output signal E2 caused by the magnetic sensor 28 also exceeds the reference voltage VR, and the output signal V4 of the exclusive OR circuit 50 becomes a low level, turning off the red light emitting diode D2, resulting in suboptimal operation. The green light emitting diode D4 related to the range C1 lights up. In this case as well, the output signal E1 caused by the magnetic sensor 26.28
Since the absolute value ΔE12 of the difference between and E2 is larger than the minute voltage ΔE, the window comparator 40 does not operate, and the green light emitting diode D6 indicating the optimum operating range C2 does not light up.

Furthermore, the magnet 24 moves in the direction of the arrow G, and the point shown in FIG. When the range is reached, the window comparator 40 operates, and the output signal V6 of the window comparator 40 becomes high level, while the AND circuit 6
Since the other input terminal of 0 is at a high level, the AND circuit 60 is inverted for the first time, and the green light emitting diode D6 lights up through the buffer 62 to indicate that the piston 4 is within the optimum operating range C2. In this case as well, the AND circuit 52 is energized and the sub-optimal operating range C1
The green light emitting diode D4, which displays , remains lit.

Next, when the magnet 24 moves further in the direction of arrow G, it reaches the position shown in FIG. (lit). Further, when the magnet 24 moves in the direction of the arrow G and reaches the state shown in FIG. Furthermore, when the magnet 24 moves in the direction of the arrow G, the red diodes D2 indicating the allowable operating range are lit one after another, as shown in FIG. The light goes out and reaches E, which is outside the allowable operating range on the right side. For these operations, see Figure 5a above.
It will be easily understood by referring to the explanation of the operation related to Sb, so it will not be explained in detail.

In this embodiment, a ring-shaped magnet 24 is used, but if the piston 4 has a structure that does not rotate itself, a block-shaped magnet such as a rectangular parallelepiped may be used. It can also be used. Therefore, the shape of the magnet is not particularly limited, and furthermore, the number of magnets is not limited as long as it is possible to form a desired magnetic field.

Further, as yet another embodiment of the present invention, in the circuit diagram shown in FIG. 4, the green light emitting diode D4 indicating the semi-optimal operating range CI and 03 and the green light emitting diode D6 indicating the optimum operating range C2 are removed, If the base terminal 70 of the transistor Q4 that drives the green light emitting diode D10 shown in FIG. 6 is connected to the output terminal of the buffer 58, and the base terminal 72 of the transistor Q6 is connected to the output terminal of the buffer 62, optimal operation A piston position detection device using so-called brightness modulation can be realized in which the brightness of the light emitting diode DIO when displaying the range C2 can be made brighter than the brightness of the light emitting diode D10 when displaying the sub-optimal operating range CI or C3.

In the above embodiment, the light emitting element is a light emitting diode, but the light emitting element is not limited to this, and it goes without saying that a lamp or the like can be used.

[Effects of the Invention] As described above, according to the present invention, a magnet is disposed on the piston, the magnitude of the magnetic field caused by the magnet is monitored by the output voltage of two magnetic sensors spaced apart by a predetermined interval, and ,
The configuration is such that the output voltages are compared using three comparators. Therefore, it is possible to detect the proper operating range of the piston in detail by separating it into the optimal operating range and the semi-optimal operating range. Even if the piston position changes slightly, there is no need to reinstall and adjust the proximity switch.

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 a conceptual explanatory diagram of the appropriate operating range, allowable operating range, etc. of a piston in a general fluid pressure cylinder; Fig. 2 is a conceptual explanatory diagram of the operating range of the piston position detection device according to the present invention; An explanatory diagram of a cylinder to which the piston position detection device according to the present invention is applied and a magnetic sensor constituting the piston position detection device; FIG. 4 is a schematic circuit block diagram of the piston position detection device according to the present invention; FIG. 5a These are operation explanatory diagrams of the piston position detecting device according to the present invention, and FIG. 6 is a circuit diagram showing another embodiment of the piston position detecting device according to the present invention. 2...Cylinder 4...Piston 24.
...Magnet 26.28...Magnetic sensor 3
4.36...Amplifier 38...Comparator 40...
・Window comparator 42...Comparator 44...Additional 3E device 4
6... Subtractor 48... OR circuit 50.
... Exclusive OR circuit 52 ... AND circuit D2 ... Red light emitting diodes D4, D6, Dlo ... Green light emitting diode Vcc.
··Power-supply voltage

Claims (5)

[Claims] (1) A first light-emitting element that indicates that the piston position in the cylinder is within the permissible range; a second light-emitting element that displays that the piston position is within the appropriate range within the permissible range; A piston position detection device comprising: a third light emitting element that indicates that the piston position is within the optimum range within the appropriate range. (2) A piston position detection device according to claim 1, wherein the first to third light emitting elements emit light of different colors. (3) In the device according to claim 1, the piston position detection device is characterized in that the second light emitting element and the third light emitting element emit light of the same color and different from that of the first light emitting element. . (4) A piston position detection device according to claim 1, in which the first light emitting element emits red light and the second light emitting element emits green light. (5) In the device according to any one of claims 1 to 4, a position configured to increase the amount of light from the second light emitting element when the piston position is within an optimal range within an appropriate range. Detection device.