JP2790435B2 - 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 in a high-temperature environment.

[0002]

2. Description of the Related Art A conventional piston position detecting device for magnetically detecting the piston position of a hydraulic cylinder is disclosed in Japanese Utility Model Publication No. 6-24722, for example. In this piston position detecting device, as shown in FIG. 7 , the magnetic detecting unit 20 is composed of two reed switches 21 and 22 having the same length of glass tube and different sensitivities. The two reed switches 21 and 22 are arranged so that their position detection directions are parallel to the axis of the cylinder tube T of the pneumatic cylinder S for detecting the piston position, and the centers of both operation ranges coincide. Placed in As a result, the operating range of the reed switch 22 with low sensitivity is included in the operating range of the reed switch 21 with high sensitivity.

[0003] The body of the piston position detector, to detect and display circuit 23 connected to the respective lead switches as shown in FIG. 8 is provided. When the piston P approaches the operating range of the reed switches 21 and 22, first, only the highly sensitive reed switch 21 is turned on, so that the red LED 24 and the infrared LED 25 are turned on. Further, when the piston P approaches, the reed switch 22 having low sensitivity is also turned on, so that the transistor 26 is turned on and the green LED 27 is turned on. At this time, when the transistor 26 is turned on, the anode potential of the LED 24 decreases and becomes lower than the voltage at which the LED 24 is turned on.
The LEDs 24 and 25 do not light. Here, the infrared LE
When the transistor 26 is turned on and the potential of the anode of the LED 24 decreases, the voltage D25 decreases due to the voltage drop.
The ED 24 is not turned on. When the piston P moves away from the center of the operation range, the reed switch 22 is turned off, so that the LED 27 is turned off and the LEDs 24 and 25 are turned on. As a result, it can be visually recognized that the piston P is in the dangerous mounting range in the range where only the LEDs 24 and 25 are turned on, and that the piston is in the optimum mounting range in the range where only the LED 27 is turned on.

In order to attach the piston position detecting device to the pneumatic cylinder S or the like, first, the piston P is arranged at a position where the piston P is to be detected in the pneumatic cylinder S. Then, the piston position detecting device is connected to the pneumatic cylinder S
Is moved toward the piston P while being in contact with the outer peripheral surface on one end side of the piston. Then, the position where the reed switch 22 is turned on during the movement and the LED 27 is turned on is marked on the pneumatic cylinder S. Next, the piston position detector is moved toward the piston P in a state where the piston position detector contacts the outer peripheral surface on the other end side of the pneumatic cylinder S. Then, similarly, the reed switch 22 is turned on and the LED is turned on.
The position where 27 lights up is marked on the pneumatic cylinder S. Finally,
The center of both the previous and current marks is the mounting position of the piston position detecting device. As a result, the piston position to be detected is set at the center of the optimum mounting range of the piston position detecting device.

[0005]

However, when detecting the piston position of the pneumatic cylinder S used in a high temperature environment (about 100 ° C.) such as a molten steel furnace, since the temperature is extremely high, the LEDs 24 and 25 are turned off. Does not work properly. Therefore, when the above piston position detecting device is mounted on the pneumatic cylinder S, the LED 24, built in the piston position detecting device,
The mounting position cannot be determined based on the lighting of 25.

Therefore, the reed switches 21 and 22 of the piston position detecting device are separated from the detection / display circuit 23, only the reed switches 21 and 22 are attached to the pneumatic cylinder S, and the detection / display circuit 23 is provided with LEDs 24 and 27. A method of arranging the device under a temperature environment in which it operates normally can be considered. However, in this case, the LEDs 24 and 27 are
From the LED 2 while moving the piston position detecting device in contact with the outer peripheral surface of the pneumatic cylinder S.
It was not easy to confirm the lighting of 4,27.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to be able to be used at a high temperature and to be able to move to a position corresponding to a predetermined piston position without display means. An object of the present invention is to provide a piston position detecting device that can be easily mounted.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, a first aspect of the present invention provides a reed switch for detecting a piston position and a reed switch for detecting a mounting position having an operation range smaller than the operation range. Consisting of a magnetic sensing element,
The operating range of the reed switch is matched with the center of the operating range of the magnetic sensing element, and the magnetic sensing element is connected to an operating range detecting device that detects the operating range of the magnetic sensing element when mounted on the hydraulic cylinder. Terminals were provided.

According to a second aspect of the present invention, in the first aspect, the magnetic detecting element is a reed switch. According to a third aspect of the present invention, in the second aspect, the longitudinal direction of the glass tube of the reed switch is disposed in a plane perpendicular to the axis of the hydraulic cylinder for detecting the piston position. I did it.

[0010]

According to the first aspect of the present invention, when the piston position is set within the operating range of the magnetic detecting element for detecting the mounting position, the piston is located substantially at the center of the operating range of the reed switch for detecting the piston position. The position is set.
When mounting the piston position detecting device at a predetermined position of the hydraulic cylinder, the piston position is detected by connecting an operating range detecting device for detecting an operating range of the magnetic detecting element to a terminal to which the magnetic detecting element is connected. I do.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, since the magnetic detecting element is a reed switch, the detection of the piston is a switching output by an on / off operation. Is output as

According to the third aspect of the present invention, in addition to the operation of the second aspect, the operating range of the reed switch as the magnetic sensing element is sufficient compared to the operating range of the reed switch. Therefore, if the piston position is set in the operating range of the reed switch as the magnetic detection element at the time of mounting, the piston position is set substantially at the center of the operating range of the reed switch.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG. As shown in FIG. 1, a piston position detecting device of the present embodiment includes a first reed switch 1 for detecting a piston position provided inside a case (not shown).
And a second reed switch 2 for detecting the mounting position. The first reed switch 1 makes the longitudinal direction of the glass tube parallel to the axis of the pneumatic cylinder S,
The second reed switch 2 is fixed on the substrate 3 which is in contact with the outer peripheral surface of the pneumatic cylinder S or the like, with the longitudinal direction of the glass tube perpendicular to the longitudinal direction of the first reed switch 1. Have been. Further, the axis of the second reed switch 2 is disposed at a position facing the center of the first reed switch 1 in the longitudinal direction. The two reed switches 1 and 2 use a center gap type reed switch in which each contact portion is arranged at the center in the longitudinal direction of the glass tube. Then, the size of the operation range of the first reed switch 1 is set to an allowable deviation range from the optimum position of the piston. The size of the operating range of the second reed switch 2 is set so that the piston position set within this operating range is set substantially at the center of the operating range of the first reed switch 1. .

Next, the electrical configuration of the piston position detecting device including the magnetic detecting section will be described. As shown in FIG.
Both ends of the second reed switch 2 of the piston position detecting device 4 are connected to connection terminals 6 for connecting a checker 5 as an operation range detecting device provided outside the piston position detecting device 4.

The checker 5 includes, for example, a DC power supply (for example, 9 V) 7, a resistor 8, and a light emitting diode (hereinafter, referred to as LED) 9. That is, the DC power supply 7
The anode of the LED 9 is connected to the plus side via the resistor 8. The negative side of the DC power supply 7 and the cathode of the LED 9 are respectively connected to a pair of terminals 10 connected to both terminals 6 of the piston position detecting device 4. The checker 5 according to the present embodiment is configured so that it can be used near the piston position detecting device 4.

On the other hand, both ends of the first reed switch 1 have a pair of terminals 1 connectable to the outside of the piston position detecting device 4.
1 connected. A DC power source 12 and a sequencer 13 for inputting the operation of the first reed switch 1 are connected to the terminals 11.

Next, the operation of the piston position detecting device configured as described above will be described. As shown in FIG.
In the pneumatic cylinder S in which the piston position detecting device 4 is mounted at the mounting position corresponding to the predetermined piston position, when the piston moves and enters the operation range of the first reed switch 1, the first reed switch 1 Exceeds the operating magnetic field MTH. As a result, the first reed switch 1 is turned on, so that an H-level signal is output to the sequencer 13. The sequencer 13 performs sequence control of the pneumatic cylinder S based on this signal.

In the pneumatic cylinder S to which the piston position detecting device 4 is attached, the strength of the magnetic field acting on each of the reed switches 1 and 2 when the piston approaches the operating range of each of the reed switches 1 and 2 is determined by the operating magnetic field MTH. by weight, the reed switch 1 and 2 you turned on, respectively. Immediate Chi,
The operating range of the first reed switch 1 is included in the operating range of the second reed switch 2, and the centers of both operating ranges coincide.

When the piston position detecting device 4 of the present embodiment is mounted at a mounting position corresponding to a predetermined piston position of the pneumatic cylinder S, for example, the following is performed. First, the piston is arranged at a position where the piston of the pneumatic cylinder S is to be detected, and the checker 5 is connected to both terminals 6 in this state.
Is brought into contact with the first end side of the cylinder tube T near the piston position. still,
At this time, the sequencer 13 and the like are not connected to the terminal 11.
Then, the piston position detecting device 4 is connected to the cylinder tube T
Of the cylinder tube T while being in contact with the outer peripheral surface of the cylinder tube T.
Move toward the end. When the piston position detecting device 4 approaches the position where the second reed switch 2 corresponds to the piston, the strength of the magnetic field acting on the second reed switch 2 exceeds its operating magnetic field MTH, so that the second reed switch 2 Turns on. Therefore, in the checker 5, a current flows from the DC power supply 7 to the LED 9 via the resistor 8 and the LED 9
9 emits light. The position of the piston position detection device 4 at this time is defined as a mounting position. In addition, since the checker 5 is configured so that it can be used near the piston position detecting device 4, the LED is moved while the piston position detecting device 4 is being moved.
9 can be easily visually recognized.

As described in detail above, according to the piston position detecting device 4 of the present embodiment, the mounting of the piston position detecting device 4 to the pneumatic cylinder S is performed only when the terminal 6 is mounted.
Is performed using the checker 5 connected to. Then, using the checker 5, the piston arranged at a predetermined position is detected in the operation range of the second reed switch 2 by turning on the LED 9. Therefore, even when the pneumatic cylinder S is in a high-temperature environment in which the LED cannot be used, the checker 5 that can visually recognize the detection of the piston by the LED 9 can be used at hand, so that the piston position can be easily detected.

Further, according to this embodiment, since the magnetic detecting element is constituted by the second reed switch 2, the detection of the piston is output as a switching output by the on / off operation of the second reed switch 2. You. Accordingly, since the checker 6 connected to the terminal 5 only needs to switch the LED 9 using the second reed switch 2 as a switch, the circuit configuration can be the simplest.

Further, according to this embodiment, the longitudinal direction of the glass tube of the second reed switch 2 is arranged in a direction orthogonal to the longitudinal direction of the first reed switch 1.
The operating range can be minimized. As a result, when the piston position detecting device 4 is mounted, the piston disposed at a predetermined position is simply detected by the second reed switch 2, and the piston position is substantially at the center of the operating range of the first reed switch 1. Can be set.

Further, according to the present embodiment, the first reed switch 1 for detecting the piston position and the second reed switch 2 for detecting the mounting position are provided independently and are insulated from each other. . Therefore, even when the load voltage is applied to the first reed switch 1, or when the voltage applied to the first reed switch 1 is an alternating current, the operation of the second reed switch 2 is the first reed switch 2. Reed switch 1
There is no side effect. Therefore, the piston position can be set at the center of the operation range of the first reed switch 1 without being affected by the second reed switch 2 side.

It should be noted that the present invention is not limited to the above embodiment, but may be configured as follows. (1) In the above embodiment, the second reed switch 2 was used as the magnetic detecting element for detecting the mounting position. However, as shown in FIG. The magnetoresistive element 13 having an operation range may be used. However, in this case, as a circuit of the checker 5, as shown in Japanese Utility Model Publication No. 6-28741, a circuit section such as a reference voltage setting circuit and a comparison circuit is required.

(2) The glass tube of the second reed switch 2 may be arranged parallel to the axis of the pneumatic cylinder S. In this case, the second reed switch 2
The sensitivity of the second reed switch 2 may be set to be lower than the sensitivity of the first reed switch 1 in order to make the operation range of the first reed switch 1 smaller than that of the first reed switch 1. Similarly, the length of the glass tube of the second reed switch 2 (that is, the length of the operating range) may be shorter than the length of the glass tube of the first reed switch 1. Further, by arranging the second reed switch 2 at a position further radially of the pneumatic cylinder S than the first reed switch 1, the operating range of the second reed switch 2 can be changed. May be configured to be smaller than the operation range.

(3) In each of the embodiments and other examples (1) and (2), the first and second reed switches 1 and 2 are arranged at positions overlapping the radial direction of the cylinder tube T. You may comprise.

(4) The second reed switch 2 is not limited to a position perpendicular to the longitudinal direction of the first reed switch 1 on the substrate 3 but may be any position within a plane perpendicular to the axis of the pneumatic cylinder S. It may be configured to be arranged at the position. In this case, the reed switches 1 and 2 may be arranged at positions overlapping the radial direction of the cylinder tube T.

(5) As shown in FIGS. 5 and 6, the first and second reed switches 1 and 2 are arranged at positions overlapping in the radial direction of the cylinder tube T, and the second reed switch 2 is moved to the first position. In the longitudinal direction of the reed switch 1 (that is,
(The same direction as the axis of the cylinder tube T)). Also in this case, the operation range of the second reed switch 2 can be set to be smaller than the operation range of the first reed switch 1.

(6) As the first and second reed switches 1 and 2, offset type reed switches having contact points offset to one end of the glass tube may be used.

[0030]

As described in detail above, according to the first aspect of the present invention, since the operating range detecting device is connected via the terminal at the time of attachment, it can be used at a high temperature. At the same time, attachment to a position corresponding to a predetermined piston position can be easily performed without the display means.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, the switching output by the on / off operation based on the detection of the piston causes the LED to emit light.
, The circuit configuration of the operation detecting device that is connected at the time of mounting and detects the operation can be most simplified.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, the piston position is set substantially at the center of the operation range of the reed switch only by detecting the piston at the time of mounting. Can be set. Therefore,
Attachment to a predetermined position such as a pneumatic cylinder can be easily performed.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a piston position detecting device.

FIG. 2 is an electric circuit diagram in which a piston position detecting device and a checker are connected.

FIG. 3 is an operation chart of a magnetic field strength and a reed switch.

FIG. 4 is a schematic plan view showing another example of the piston position detecting device.

FIG. 5 is a schematic plan view showing a piston position detecting device.

FIG. 6 is a schematic front view of the position detection device.

FIG. 7 is a schematic plan view showing a conventional piston position detecting device.

FIG. 8 is an electric circuit diagram of a piston position detecting device.

[Explanation of Signs] 1. First reed switch for detecting piston position
2, a second reed switch as a reed switch for detecting an attachment position; 5, a checker as an operating range detecting device; 6, a terminal; S, a pneumatic cylinder as a fluid pressure cylinder.

Claims (3)

(57) [Claims] 1. A reed switch (1) for detecting a piston position, and a magnetic detection element for detecting a mounting position having an operation range smaller than the operation range thereof. A terminal (5) for matching the center of each operating range of the detecting element and connecting the magnetic detecting element to an operating range detecting device (5) for detecting the operating range of the magnetic detecting element when attached to the hydraulic cylinder (S). A piston position detecting device provided with 6). 2. The piston position detecting device according to claim 1, wherein the magnetic detecting element is a reed switch (2). 3. A hydraulic cylinder (S) for detecting a piston position in a longitudinal direction of a glass tube of a reed switch (2).
The piston position detecting device according to claim 2, wherein the piston position detecting device is arranged in a plane perpendicular to the axis of the piston.