JPH0315909A - Position detection device for fluid pressure operation unit - Google Patents

Abstract

PURPOSE:To secure a sufficient detection signal time width even if a magnetism generator moves at high speed by permitting a switch to execute an on-operation in the going route of the reciprocating movement of the magnetic generator and holding the on-state until the magnetism generator passes through a detection element in a return route. CONSTITUTION:When the piston of a fluid pressure operation unit approaches to the Hall switch 1 from the return route, the switch is turned on when the magnetic flux density of the magnetism generator in the fluid pressure operation unit reaches the operation level point (a) of the Hall switch 1. When the movement of the piston of the fluid pressure operation unit changes from the forward route to the return route, a magnet being the magnetism generator approaches the Hall switch 1 and reaches the operation level point (b) of a negative magnetic field, the on-operation changes to an off-operation. Namely, a detection signal is outputted for a long time irrespective of the operation speed of the piston in the fluid pressure operation unit, because a negative magnetic field holds the on-state. Thus, it is prevented that the signal is failed to be detected in a sequencer and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position detection device for fluid pressure operated devices, and particularly for fluid pressure operated devices such as cylinders and low reactuators equipped with moving members such as reciprocating pistons. The present invention relates to a technique that is effective when applied to detecting the position of equipment.

[Conventional technology]

There is a technology that detects the movement of a piston sliding inside a cylinder in response to fluid pressure such as air pressure, and controls the operation of a controlled device such as a solenoid valve based on the detected output.

A position detection sensor such as a reed switch, a Hall element, or a magnetic resistance element is generally used to detect the position of the piston within the cylinder. Among these, those using a Hall element utilize the fact that a magnet is attached to a piston, and when the magnetic field of the magnet cuts the Hall element, a voltage is generated from the output terminal of the element. The output voltage of the Hall element is sent to a comparison circuit such as an operational amplifier, and after processing such as amplification, is used to drive a display or other control circuits.

It should be noted that the Hall element of a position detection device is rarely used as a stand-alone device, but instead is a digitally operated switch unit (hereinafter referred to as a Hall switch) that generates an on-voltage when the strength of the magnetic field exceeds a certain level. Generally used.

[Problem to be solved by the invention]

However, in the above-mentioned position detection device for fluid pressure operated equipment using the Hall switch, since the Hall element is in the on state while a magnetic field is applied, it is detected only at the relative movement interval (for example, 5 mm) between the Hall element and the piston. A signal was being output. For example, when the detection width is 51II1 and the piston speed is V, the signal width time for each speed V is as follows.

When v=lm/sec, signal width time=51IISv=2m
/second, the signal width time -2. 5 msv = 5 m/sec, signal width time = lms Therefore, when the piston passes at high speed, a detection signal is generated for only a very short time, and when the detection signal is used in a control device such as a sequencer, there is a possibility of a detection error. There was a risk that this would occur.

An object of the present invention is to provide a technique that can obtain a sufficient detection signal time width even when a moving member of a fluid pressure operated device operates at high speed.

[Means to solve the problem]

The position detection device for a fluid pressure operated device of the present invention uses, as a sensor, a detection element that generates an electric signal in response to the approaching passage of a magnetic generator attached to a piston provided in a fluid pressure operated device so as to be movable back and forth. In a position detection device configured using a switch, the switch turns on on the outward path of the reciprocating movement of the magnetic generating body and maintains the on state until the magnetic generating body passes the detection element on the returning path. It is made to have characteristics.

In addition, depending on the desired function, the detection element may include a Hall element,
A magnetoresistive element or a reed switch can be used.

[Effect]

According to the above-mentioned means, the magnetic generator of the fluid pressure operated device is switched on when heading toward the switch from the outward path,
When the passed magnetic generator passes through the switch on its return path, the switch operation is changed from on to off. In other words, it remains on during the outward journey and is turned off when the returning magnetic generator passes through the switch, so it remains on during that time and even if the magnetic generator moves at high speed. Unlike the conventional method, the detection signal does not become extremely short.

Further, in the present invention, the switch is turned on and held in the on state on the outward path of the reciprocating movement of the magnetic generator, and the on state is reset from the outside, and the on state is maintained again on the return path. By providing a position detection device for a fluid pressure operated device characterized by having the above-mentioned characteristics, the same effects as described above can be obtained.

By using a Hall element as the detection element and making the element itself self-holding, the operating state can be maintained by itself, making it possible to apply it to high-speed moving fluid pressure-operated equipment while simplifying the configuration around the detection element and the subsequent circuit. Become.

Further, by using a magnetoresistive element or a reed switch as the detection element, storage and reset processing for the detection signal can be performed electrically.

[Example 1]

First, an embodiment in which a Hall element is used as a detection element and a switch is constructed using this Hall element will be described.

FIG. 1 is a block diagram showing a first embodiment of a position detection device for a fluid pressure operated device according to the present invention. Moreover, FIG. 2 is a characteristic diagram showing the characteristics of the Hall switch 1 as a switch.

As shown in FIG. 1, a Hall switch 1 using a Hall element 1l is attached to the outer periphery of a fluid pressure operated device (not shown), and is mounted on a piston that is reciprocatably mounted within the fluid pressure operated device. When a magnetic generating body such as a magnet approaches, it generates a binary signal voltage according to its magnetic force and polarity. An output circuit 2 is connected to the Hall switch 1, which converts the input binary signal voltage into a signal form required by the sequencer and outputs it. Further, a light emitting diode 4 is connected between the DC power supply Vc and the output terminal of the Hall switch l via a current limiting resistor 3, and lights up to indicate whether or not a magnetic generator of the fluid pressure operated device is detected.

The Hall switch 1 includes a Hall element 11 that converts the magnetic change of a magnet as a magnetic generator provided on a piston that is reciprocally mounted in a fluid pressure operated device into a voltage change, and converts the output voltage of the Hall element 11 into a voltage change. #l is provided by a signal processing section 12 consisting of an amplifying amplifier, a comparator, a display, etc., and an output transistor 13 operated by the output voltage of the signal processing section 12.

In the Hall switch 1, the Hall element 11 is arranged so that the magnetically sensitive surface becomes the south pole, and its characteristics are as shown in FIG. On the outward journey, the magnetic generator of the fluid pressure operated device enters from the direction of the arrow 8 in Fig. 2, and operates so that the output transistor 13 is turned on when the positive magnetic field reaches a predetermined level. When the generator enters and reaches a predetermined level of negative magnetic field, the output transistor 13 operates from on to off. That is, it has a characteristic that it is turned on by a positive magnetic field, and once turned on, it remains on until a negative magnetic field is activated.

Next, the operation of the above embodiment will be explained.

First, when the piston of the fluid pressure operated device approaches the Hall switch 1 from the outward path, the switch is turned on when the magnetic flux density of the magnetic generator of the fluid pressure operated device reaches the operating level point a of the Hall switch 1.

At this time, the signal processing unit 12 outputs a "1" level voltage, the output transistor 13 changes from OFF operation to ON operation, and the output transistor 13 becomes conductive, causing the light emitting diode 4 to light up and notify the position detection. Output times 12
generates a signal required by the sequencer when the output transistor 13 changes from OFF operation to ON operation.

Then, when the movement of the piston of the fluid pressure-operated device changes from the outward path to the backward path and the magnet, which is the magnetic field generator, approaches the Hall switch I and reaches the operating level of the negative magnetic field at point b, the on operation changes to the off operation.

By this operation, the signal processing unit l2 returns to the "0" level, the output transistor l3 is returned to a non-conductive state, and the light emitting diode 4 is turned off. Further, the output circuit 2 recognizes that the detection signal disappears when the output transistor 13 is turned off, and stops outputting the signal to the sequencer.

As described above, according to the embodiment shown in FIG. 1, since the ON state is maintained by the positive magnetic field, the detection signal is output for a long time regardless of the operating speed of the piston of the fluid pressure operated device. Therefore, there is no possibility that a sequencer or the like fails to detect a signal. In addition, since the passing state can be maintained, when the piston of the fluid pressure operated device is stationary, it is possible to judge which side the piston of the fluid pressure operated device is on with respect to the Hall switch 1 from the state of the detection signal. I can do it.

Incidentally, in the above embodiment, the Hall switch has a memory function, but in order to reset it, it is necessary to apply a magnetic field from the outside.

Further, it is not possible to specify whether to set or reset the power on/off (eg, set when the power is turned on, reset when the power is turned off, etc.).

To solve this problem, instead of using a Hall element as the detection element, a magnetoresistive element, a reed switch, or the like may be used. Examples thereof will be described below with reference to the drawings.

[Example 2] FIG. 3 is a block diagram showing a second embodiment of the present invention.

In the embodiment of FIG. 3, the detection element 5 is a magnetoresistive element or a reed switch.

A signal processing section 6 is connected to the detection element 5, which processes the change in the analog voltage into a binary change signal. This signal processing section 6 includes a storage circuit 7 for storing its operating state.
(For example, a non-volatile memory and a backup battery are used) are connected, and the memory contents can be reset by an externally applied reset signal. L depending on
An output circuit 8 is connected to drive an ED display 9 or to output an output signal to the outside.

FIG. 4 is a sectional view showing a state in which the sensor switch 10, which includes the detection element 5, the signal processing section 6, and the storage circuit 7, is installed.

A piston 15 as a reciprocating member is provided at the tip of the piston rod 14, and an annular magnet 16 is embedded in the outer periphery of the piston 15.

A cylindrical cylinder 1 into which a piston l5 is reciprocatably fitted.
7 is fixedly installed, and a sensor switch 10 is arranged on the detection position line on its outer periphery. This sensor switch 10
Each time the piston 15 passes through a portion facing the piston 15, an electric signal corresponding to the direction of movement is output from the signal processing section 6.

Next, regarding the operation of the embodiment according to the structure of FIG.
This will be explained with reference to the figures.

First, when the piston 15 approaches the sensor switch 10 while moving from the returning path to the outgoing path when the switch is off on the return trip, the detection element 5 is a magnetic resistance element in response to the approach of the magnet 16. When the signal increases in an analog manner and exceeds the threshold value, the signal processing section 6 generates an on signal as shown in FIG. 5(a) and turns on the switch. Moreover, when the detection element 5 is a reed switch,
When the magnetic force applied by the magnet 16 exceeds a certain level, a detection signal is output, and the signal processing unit 6 outputs a detection signal as shown in FIG.
) to generate an on signal. These operating states are
Even after the magnet 16 has passed the position facing the detection element 5, it is retained in the memory circuit 7.

On the other hand, when the piston 15 is reset on the outward journey and moves from the return journey to the outward journey while remaining switched on on the return journey, when the magnet 16 reaches the position facing the detection element 5 of the sensor switch 10, the fifth As shown in Figure (b), the switch turns off. This off state is maintained until the magnet 16 passes the detection position next.

Also, when the switch is on, the piston l5 moves from the outward path to the return path.
When the magnet l6 moves, as shown in FIG. 5(C), when the magnet l6 passes a position facing the detection element 5, it turns from on to off. Furthermore, when the piston 15 moves from the forward path to the return path while the switch is in the OFF state after a reset is performed, the OFF state occurs when the piston 15 passes the position facing the detection element 5 through the magnet 16, as shown in FIG. Turns on from.

In this way, the position facing the detection element 5 is set using the magnet l.
The operating state (on or off) force is reversed every time 6 passes. Further, if a reset is applied while the device is in the on or off state, the operating state is immediately reversed. Note that if the switch is turned on during the outward trip and then reset and turned off, the switch will be turned on on the return trip.

Furthermore, when the power is "off", the power supply to each circuit is cut off, but since the present invention is provided with the memory circuit 7, it is possible to keep track of the operating state at that time. ! 4 (on or off) is memorized, and even if the power is turned to "man" again, the state before the power was turned off is preserved.

Although the invention made by the present invention has been specifically explained based on Examples above, it goes without saying that the present invention is not limited to the above-mentioned Examples and can be modified in various ways without departing from the gist thereof. .

For example, the present invention can be widely applied to detecting the position of not only air cylinders but also moving members such as hydraulic cylinders or vanes of low reactor actuators.

〔Effect of the invention〕

According to the present invention, a switch whose sensor is a detection element that generates an electric signal in response to the approaching passage of a magnetic generator attached to a moving member provided in a fluid pressure operated device is used.
I. A position detection device in which the switch has a characteristic of turning on during the outward movement of the magnetic generating body and maintaining the on state until the magnetic generating body passes the detecting element on the backward movement. As a result, even if moving parts or magnetic generating bodies of fluid pressure operated equipment move at high speed,
A sufficient detection signal time width can be ensured.

Furthermore, by using a Hall element as the detection element, it is possible to simplify the peripheral circuit of the detection element and the subsequent circuit, and it is possible to apply the detection element to high-speed moving fluid pressure operated equipment.

Furthermore, by using a magnetoresistive element or a reed switch as the detection element, storage and resetting can be electrically processed without the detection element itself having self-holding characteristics or reset means other than electrical means. Become.

Furthermore, the switch has the characteristic of turning on and maintaining the on state on the outward journey of the magnetic generator's reciprocating movement, and also resetting the on state from the outside and maintaining the on state again on the return journey. By providing a position detection device for a fluid pressure operated device characterized by the following, the same effects as described above can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the position detection device for fluid pressure operated equipment according to the present invention, FIG. 2 is a characteristic diagram showing the characteristics of the Hall switch in the embodiment of FIG. 1, and FIG. FIG. 4 is a cross-sectional view illustrating the installation state of the sensor switch shown in FIG. 3, and FIG. FIG. 3 is a switch characteristic diagram illustrating the operation. 1... Hall switch, 2.8... Output circuit, 4 ・ 5 ・ 6, 7 ・ 1 0 ・ 1 1 ・ 1 3 ・ Light emitting diode, detection element, signal processing unit, memory circuit, sensor input , Hall element, output transistor. 1 Figure 1

Claims (5)

[Claims] 1. A position detection device that uses a switch whose sensor is a detection element that generates an electric signal in response to the approaching passage of a magnetic generator attached to a movable member that is reciprocally provided in a fluid pressure operated device. and that the switch has a characteristic of being turned on during the forward path of the reciprocating movement of the magnetic generating body and maintaining the on state until the magnetic generating body passes the detecting element on the returning path. Characteristic position detection device for fluid pressure operated equipment. 2. 2. The position detection device for fluid pressure operated equipment according to claim 1, wherein the detection element is a Hall element. 3. 2. The position detection device for fluid pressure operated equipment according to claim 1, wherein the detection element is a magnetoresistive element. 4. 2. The position detection device for fluid pressure operated equipment according to claim 1, wherein the detection element is a reed switch. 5. A position detection device that uses a switch whose sensor is a detection element that generates an electric signal in response to the approaching passage of a magnetic generator attached to a movable member that is reciprocally provided in a fluid pressure operated device. The switch has a characteristic of turning on and maintaining the on state on the outward path of the reciprocating movement of the magnetic generating body, and resetting the on state from the outside and maintaining the on state again on the return path. A position detection device for fluid pressure operated equipment, characterized in that: