JP2857332B2 - Piston position detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston position detecting device, and more particularly to a piston position detecting device for magnetically detecting a piston position of a hydraulic cylinder.

[0002]

2. Description of the Related Art Conventionally, as such a piston position detecting device, there is, for example, a magnetic proximity switch disclosed in Japanese Utility Model Publication No. 6-24722. As shown in FIG. 4, this magnetic proximity switch is a reed switch 9 having different sensitivities.
1, 92 are arranged parallel to the axis of the cylinder tube T. As shown in FIG. 5, each reed switch 91, 9
2 is connected in parallel to the power supply line. When the sensitive reed switch 91 is first turned on by the approach of the piston P, the power supply voltage is changed to the reed switch 91, the diode 93,
The voltage is applied to the LEDs 95 and 96 via the resistor 94. On the other hand, a high-level signal is input to the base of the switching transistor 97 and the switching transistor 97 is turned on.
Is in the off state, the switching transistor 98 does not turn on. As a result, only the LED 96 is turned on, and LE
D95 does not light. When the piston P moves further,
Reed switch 91 remains on and reed switch 9
2 turns on. Therefore, the switching transistor 98
Is turned on, a power supply voltage is applied to the LED 95.
As a result, both the LEDs 95 and 96 are turned on. When the piston P moves further and the reed switch 92 turns off,
As described above, since the switching transistor 98 is turned off, the LED 95 is turned off and only the LED 96 is turned on. As a result, in the range where the piston P is detected only by the reed switch 91 (that is, the allowable range), the LED 96 is detected.
Is turned on, and the LED 95 is turned on in a range that can be detected by the reed switch 92 (that is, an optimum range). Therefore, it is determined whether the piston P is in the optimum range or not and in the allowable range.

[0003] When the magnetic detection switch is mounted on the cylinder tube T, a mounting position is set in which the actual stop position of the piston P and the optimum range of the magnetic detection switch correspond.

[0004]

However, when a pneumatic cylinder having a magnetic proximity switch attached to a predetermined position is actually used in a process or the like as described above, the actual stop position of the piston is attached due to deformation of a work or the like. The magnetic detection switch may deviate from the optimum range and fall within the allowable range. In this case, the mounting position of the piston position detecting device is readjusted so that the actual piston position falls within the optimum range. However, it was not possible to determine which side of the two allowable ranges on both sides of the optimum range the actual piston position was, so that the adjustment could not be performed immediately.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to determine which side of the optimum range the piston stops when the piston stop position is out of the optimum range. It is to provide a piston position detecting device.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a first reed switch,
A second reed switch and a third reed switch are provided. The detection range of the first reed switch and a part of the detection range of the second reed switch overlap, and the detection range of the second reed switch and the third reed switch are different. The first and second reed switches are displaced in the position detection direction so that the detection ranges of the switches overlap with each other and the detection ranges of the first and third reed switches do not overlap.
The first light emitting element is turned on by setting the detection range in which only the reed switch is turned on as the first allowable range, and at least the second light emitting element is turned on.
The second light-emitting element is turned on with the detection range where the reed switch is turned on as the optimum range, and the third light-emitting element is turned on with the detection range where only the third reed switch is turned on as the second allowable range. .

According to a second aspect of the present invention, in the piston position detecting device of the first aspect, a first light emitting element is connected in series to a first reed switch, and a second light emitting element is connected to a second reed switch. The light emitting elements were connected in series, and the third light emitting element was connected in series to the third reed switch.

According to a third aspect of the present invention, in the piston position detecting device according to the second aspect, a series circuit including each reed switch is connected in parallel, and the series circuit of the first reed switch and the third reed switch. Switching diodes were connected in series to the series circuits of the switches.

According to a fourth aspect of the present invention, in the piston position detecting device of the first aspect, instead of disposing the reed switches in the position detecting direction as described in the first aspect, the first position is changed to the first position. And the third reed switch are offset type reed switches,
Without shifting the reed switch and the third reed switch in the direction of position detection with respect to the second reed switch.
A piston position detecting device arranged such that a contact point of a first reed switch and a contact point of a third reed switch are on opposite sides.

[0010]

Therefore, according to the first aspect of the present invention, the first reed switch which is displaced in the position detection direction,
A detection range detected by only the first reed switch, a detection range detected by at least the second reed switch, and a detection range detected by only the third reed switch by the second reed switch and the third reed switch. Is formed. The detection range in which the first reed switch is turned on is the first allowable range, the detection range in which at least the second reed switch is turned on is the optimal range, and the detection range in which the third reed switch is turned on is the second allowable range. And the first to third light emitting elements are turned on corresponding to each detection range.

According to the second and third aspects of the present invention, in addition to the operation of the first aspect, the circuit configuration can be simplified and the number of parts can be reduced. it can.

According to the fourth aspect of the invention, in addition to the operation of the first aspect, the first reed switch and the third reed switch are positioned with respect to the second reed switch. Since they are arranged without being shifted in the detection direction, the size can be suppressed.

[0013]

FIG. 1 shows an embodiment of the present invention.
Explanation will be made according to 2. As shown in FIG. 1, the magnetic detecting unit 61 of the piston position detecting device of the present embodiment includes a first reed switch 62, a second reed switch 63, and a third reed switch 64 having the same detection range with the same sensitivity. It is configured. These three reed switches 62, 63,
The reference numeral 64 is arranged such that the respective detection directions are parallel to each other and the respective contact portions are shifted by a distance d in the detection direction. When the piston position is within the first allowable range with respect to the piston position detecting device, only the reed switch 62 is turned on. When the piston position is within the optimum range, at least the reed switch 63 is turned on.
When the piston position is within the second allowable range, only the reed switch 64 is turned on. The magnetic detector 61 is mounted on a circuit board provided inside a case (not shown) of the piston position detecting device.

Next, the reed switches 62, 63, 6
4 will be described. As shown in FIG. 2, a reed switch 62, a switching diode 67, and a red LED 6 as a first light emitting element are provided between a power supply line 65 (positive input line) and a ground line 66 (negative side).
8 are connected in series. Switching diode 6
7. The LED 68 is connected with the anode on the positive side. A reed switch 63 is provided between the power supply line 65 and the ground line 66, and a green L as a second light emitting element.
The ED 69 is connected in series. The LED 69 is connected with the anode on the plus side. A reed switch 64, a switching diode 70, and a red LED as a third light emitting element are provided between the power supply line 65 and the ground line 66.
71 are connected in series. Switching diode 7
0 and the LED 71 are connected with the anode on the plus side, respectively. Therefore, each of the above reed switches 62, 6
The series circuits including 3, 64 are connected in parallel with each other.
Further, a zener diode 72 is connected between the power supply line 65 and the ground line 66 with its anode on the negative side.

Next, the operation of the piston position detecting device configured as described above will be described. As shown in FIG. 1, the piston position detecting device of the present embodiment is used, for example, fixed to the outer peripheral surface of a cylinder tube T of a pneumatic cylinder S in which a ring-shaped magnet M is mounted on the outer peripheral side of a piston P. You. FIG. 1 is a schematic diagram showing an attached state, and the dimensional relationship is different from the actual one. The piston position detecting device includes the reed switches 62, 63,
64 is fixed to the outer peripheral surface of the cylinder tube T so that the detection direction is parallel to the axis of the cylinder tube T. Further, the contact portion of the reed switch 63 is arranged so as to correspond to a predetermined stop position of the piston P.

In the pneumatic cylinder S equipped with the piston position detecting device, the moving piston P
Approach from the reed switch 62 side, first, the magnetic field of the magnet M
, The reed switch 62 is turned on. As a result, a current flows through the switching diode 67 and the LED 68, so that only the red LED 68 is turned on. Therefore, the operator can easily visually recognize that the piston position is within the first allowable range.

Further, when the piston P moves in the same direction, a magnetic field acts on the reed switches 62 and 63.
Both the reed switches 62 and 63 are turned on. When both the reed switch 63 and the reed switch 62 are turned on, a circuit of the reed switch 62, the switching diode 67 and the LED 68, and a circuit of the reed switch 63 and the LED 69 are formed between the power line 65 and the ground line 66. However, since the voltage drop of the circuit including the switching diode 69 is large and almost no current flows to the LED 69, only the green LED 69 is turned on. Therefore, the operator can easily visually recognize that the piston position is within the optimum range.

Further, when the piston P moves in the same direction, the magnetic field acts only on the reed switch 63, so that only the reed switch 63 is turned on. As a result, LED6
Since the current flows through only the LED 3, the green LED 69 is turned on. In this case, the operator can easily visually recognize that the piston position is within the optimum range.

When the piston P moves in the same direction, a magnetic field acts on the reed switches 63 and 64, so that both the reed switches 63 and 64 are turned on. Also in this case, since the current flows through the LED 69, similarly, the green LED 69
Lights up. Therefore, the operator can easily visually recognize that the piston position is within the optimum range.

Further, when the piston P moves in the same direction, the magnetic field acts only on the reed switch 64, so that only the reed switch 64 is turned on. As a result, a current flows through the switching diode 70 and the LED 71,
Only the red LED 71 lights up. Therefore, the operator can easily visually recognize that the piston position is within the second allowable range.

Since a zener diode 72 is connected between the power supply line 65 and the ground line 66, a large voltage is applied to each of the switching diodes 67, 70 and 70 when each of the reed switches 62, 63, 64 is turned on. Each LED6
8, 69 and 71 are not applied.

As described in detail above, in the piston position detecting device of this embodiment, since the direction in which the piston position deviates from the optimum range can be easily known, the mounting position of the piston position detecting device must be readjusted. It can be done easily.

Further, the piston position detecting device of the present embodiment
Since a part of each detection range of the adjacent reed switches 62, 63, and 64 is overlapped with each other to form a first allowable range, an optimum range, and a second allowable range, the first and second allowable ranges or the optimum ranges are formed. It is possible to reliably detect the position of the piston located inside.

Further, the piston position detecting device of this embodiment is provided with three reed switches 62, 63, 64, and each of the reed switches 62, 63, 64 turns on another LED 68, 69, 71, respectively. As a result, the circuit configuration can be simplified as compared with the conventional magnetic detection switch. Therefore, the number of components can be reduced, and the size of the circuit board can be reduced.

In the piston position detecting device of this embodiment, the detection range is widened by sequentially shifting the three reed switches 62, 63, 64 by a predetermined distance to form a detection range. Therefore, when the cylinder to which the piston position detecting device is attached has a variation in the piston stop position such as a clamping cylinder, it is possible to avoid a trouble in which the piston position is not detected due to the variation.

It should be noted that the present invention is not limited to the above-described embodiment, but may be configured as follows. (1) As shown in FIG. 3, offset type reed switches 84 and 8 (center gap type in which a contact is provided at the center of a glass tube) are replaced with reed switches 62 and 64.
5, the magnetic detection unit 86 may be configured such that the reed switches 84 and 85 are arranged so that the respective contacts are on opposite sides without being shifted with respect to the reed switch 63 in the position detection direction. In this case, the size of the magnetic detection unit 86 in the axial direction can be suppressed.

(2) In the above embodiment or another example (1), a reed switch having a detection range longer than the detection range of the reed switch 63 may be used for the reed switches 62 and 64. In this case, the first and second allowable ranges can be made wider than the optimum range.

(3) In the above embodiment, the LEDs 68, 6
Instead of 9, 71, another light emitting or display element, for example, an electroluminescent element (EL element), a liquid crystal element, or the like may be used to display the optimum range and the first and second allowable ranges in a distinguishable manner. .

(4) In the above embodiment, the LEDs 68, 6
9 and 71 may be the same color, or the color combination may be a color other than the combination of green and red. Furthermore, LED
The colors 68 and 71 may be different colors instead of the same color. In this case, it is easier to determine which side the piston stop position has shifted to the allowable range.

(5) In the above embodiment, each LED 68, 6
The signals output to the components 9 and 71 may be taken out of the piston position detecting device, and the operation of the pneumatic cylinder S may be managed based on these signals. For example, when the piston stop position is continuously detected in the first or second allowable range a predetermined number of times, a warning or the like is turned on, and each LED 68,
Correction of the mounting position of the piston position detecting device is performed according to the display of 71.

[0031]

As described in detail above, according to the first aspect of the present invention, when the piston position deviates from the optimum range,
Which side of the optimum range has been shifted can be easily determined by turning on the light emitting element.

According to the second and third aspects of the present invention, in addition to the effects of the first aspect, the circuit configuration can be simplified and the number of parts can be reduced. it can.

According to the invention described in claim 4, in addition to the effect of the invention described in claim 1, the first reed switch and the third reed switch are positioned with respect to the second reed switch. Since they are arranged without being shifted in the detection direction, the size can be suppressed.

[Brief description of the drawings]

FIG. 1 is a plan view of a magnetic detection unit of a piston position detection device according to an embodiment.

FIG. 2 is a circuit diagram of a piston position detecting device.

FIG. 3 is a plan view of a magnetic detection unit of another example of the piston position detection device.

FIG. 4 is a plan view of a magnetic detection unit of a conventional magnetic proximity switch.

FIG. 5 is a circuit diagram of a magnetic proximity switch.

[Explanation of symbols]

62: a first reed switch; 63, a second reed switch; 64, a third reed switch; 68, an LED as a first light emitting element; 69, an L as a second light emitting element
ED, 71 ... LED as third light emitting element, 67, 7
0: Switching diode.

Continued on the front page (56) References JP-A 4-66744 (JP, U) JP-A 63-67808 (JP, U) JP-A 2-37309 (JP, U) JP-A 2-27501 (JP , U) Tokiko 1-39526 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 7/00 F15B 15/28

Claims (4)

(57) [Claims] A first reed switch (62), a second reed switch (62)
The reed switch (63) and the third reed switch (6
4), the detection range of the first reed switch (62) and the second
Part of the detection range of the switch (63) overlaps,
Detection range of reed switch (63) and third reed switch
Switch (64) overlaps a part of the detection range,
Detection range of the reed switch (62) and the third reeds
Each lead so that the detection range of the switch (64) does not overlap.
The switch is displaced in the position detection direction, and a detection range in which only the first reed switch (62) is turned on.
The first light emitting element (68) is turned on by setting the first allowable range.
And at least a second reed switch (62, 63)
The second light emitting element with the detection range in which
(69) is turned on, and the third reed switch (64) is turned on.
The third detection range is set as the detection range in which only the
Piston position detection that turns on the optical element (71)
Output device. 2. The piston position detecting device according to claim 1,
Here, the first light emitting element is connected to the first reed switch (62).
And a second reed switch (6).
3) A second light emitting element (69) is connected in series to the third light emitting element (69).
The third light emitting element (71) is connected in series with the mode switch (64).
Connected piston position detector. 3. The piston position detecting device according to claim 2,
Including each reed switch (62, 63, 64)
A series circuit connected in parallel, a first reed switch (62)
And the series circuit of the third reed switch (64).
Switching diodes (67, 70) on the road
Are connected in series. 4. A piston position detecting device according to claim 1,
In addition, each reed switch (6
2, 63, 64) in the position detection direction.
Instead of the first reed switch and the third reed switch.
Switch to an offset type reed switch (84, 85)
And a first reed switch (84) and a third reed
The switch (85) is connected to the second reed switch (63).
The first lead switch without shifting in the position detection direction.
Switch (84) and the third reed switch (85).
Piston position detection arranged so that the contact is on the opposite side
apparatus.