JP3951874B2 - Piston position detection device for hydraulic actuator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piston position detection device for a hydraulic actuator.
[0002]
[Prior art]
By adjusting the hydraulic pressure in the first hydraulic pressure chamber defined on the top surface side of the piston and the second hydraulic pressure chamber defined on the bottom surface side of the piston slidably disposed in the casing, Hydraulic actuators that control position are well known. In such a hydraulically operated actuator, as a device for detecting the piston position, a part acting on the object to be displaced by the hydraulically actuated actuator, for example, a part protruding outside the casing of the piston (hereinafter referred to as “action”). An apparatus for detecting the position of the "part" is known (for example, see Patent Document 1).
[0003]
Since such a piston position detecting device detects the position of the action part, it is necessary to be provided on the side of the action part of the hydraulic actuator (hereinafter referred to as “action part side”). is there. On the other hand, the hydraulically operated actuator as described above is usually attached to the device to which the actuator is attached (that is, the device having the object) with the action portion side facing toward the device. It is done.
[0004]
For this reason, when using a piston position detection device that detects the position of the action portion as described above, the piston position detection device may have to be mounted inside the device to which the actuator is mounted. This imposes various mounting constraints and may cause maintenance inconveniences.
[0005]
[Patent Document 1]
Japanese Utility Model Publication No. 4-54301 [Patent Document 2]
JP-A-9-31620 Gazette
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a piston position detection device that is attached to the side opposite to the action portion side of the hydraulic actuator and that is easy to install. Is to provide.
[0007]
[Means for Solving the Problems]
The present invention provides, as means for solving the above-mentioned problems, a piston position detecting device described in each claim.
[0008]
A first invention is a hydraulically operated actuator that controls the position of a piston slidably disposed in a casing by adjusting the hydraulic pressure in the hydraulic chamber, and is intended to be displaced by the hydraulically operated actuator. Detects the piston position of a hydraulically-actuated actuator having an action part side end surface projecting from the casing and a non-action part side end face opposite to the action part side end face. to a piston position detector, and a movable portion which is arranged in the non-working part-side end face through a hole in the casing of the hydraulic operated actuator, in contact without being attached to said piston, said as the movable portion is displaced in conjunction with the piston, said pin and said movable portion a contact maintaining means to maintain the contact between the movable portion and the piston Covering a contact maintaining means comprising a resilient member biasing toward ton top surface of the hole in the casing of the hydraulic operated actuator in the non-working part-side end face, and includes the movable portion therein And a movable part position detecting means for detecting the position of the movable part. The position of the piston is detected by detecting the position of the movable part. And a means for reducing a hydraulic pressure difference between the hydraulic pressure chamber and the cap portion, and the cap portion supports the movable portion so as to be slidable. Provided is a piston position detecting device characterized by comprising means .
[0009]
According to the present invention, there is provided a piston position detection device attached to the side opposite to the action part side of the hydraulic actuator. Usually, in order to perform the actuator function, the hydraulically operated actuator as described above is attached to the device to which the actuator is attached (that is, the device having the object) with the action portion side directed. Therefore, according to the present invention, it becomes possible to mount the piston position detecting device on the opposite side of the device to which the actuator is mounted, and this facilitates the mounting and maintenance of the piston position detecting device. Further, since the movable part is not attached to the piston, the degree of freedom of attachment of the piston position detecting device is increased, and attachment is facilitated.
[0010]
That is, the contact maintaining means includes an elastic member that urges the movable portion toward the top surface of the piston, and maintains the contact between the movable portion and the piston by a simple method. since it is, may not be fixedly coupling the said movable portion and said piston, the attachment of the piston position detector is facilitated.
[0011]
The piston position detecting device of the present invention is further characterized by further comprising means for reducing a hydraulic pressure difference between the hydraulic chamber and the cap portion .
When the hydraulic fluid in the hydraulic chamber enters the cap portion through the hole or the like provided in the casing, the elastic member that the contact between the movable portion and the piston urges the movable portion toward the top surface of the piston. If only the pressure is maintained, the movable portion may be separated from the piston when the hydraulic pressure difference between the hydraulic chamber and the cap portion increases. Since the piston position detection device of the present invention attempts to detect the position of the piston by detecting the position of the movable part, when the movable part moves away from the piston, the accurate position of the piston is detected. become unable. According to the present invention , since the hydraulic pressure difference between the hydraulic pressure chamber and the cap portion is reduced, the movable portion is prevented from being separated from the piston, and the accuracy of detecting the piston position is improved.
[0012]
Furthermore, the piston position detection device of the present invention is characterized in that the cap portion has a supporting means for slidably supporting the movable portion .
Thereby , according to this invention, since the said movable part is slidably supported by the support means which the said cap part has, the said movable part will slidably move within the predetermined | prescribed track | orbit. This is preferable in accurately detecting the position of the movable part. As described above, since the piston position detection device of the present invention is intended to detect the position of the piston by detecting the position of the movable portion, this feature improves the detection accuracy of the piston position.
The second invention is characterized in that, in the first invention, the hydraulic pressure difference reducing means is constituted by a hole communicating the hydraulic pressure chamber and the cap portion.
[0013]
Furthermore, a third invention is characterized in that in the first or second invention , the movable part position detecting means includes a potentiometer.
According to the present invention, the movable portion position detecting means can be configured easily and inexpensively, and the mounting of the piston position detecting device can be facilitated and the cost of the piston position detecting device can be reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing a hydraulic actuator 11 provided with a piston position detecting device 10 according to an embodiment of the present invention.
[0015]
The hydraulic actuator 11 (hereinafter simply referred to as “actuator”) has a casing 13 and a piston 15 slidably disposed in the casing 13. The piston 15 has a portion (hereinafter referred to as “action portion”) 17 that acts on an object (not shown) to be displaced by the actuator 11 and protrudes to the outside of the casing 13. In the casing 13, a first hydraulic chamber 23 is defined on the top surface side of the piston 15, and a second hydraulic chamber 25 is defined on the bottom surface side of the piston 15. In the present embodiment, the actuator 11 is operated by hydraulic pressure. Therefore, hereinafter, the first hydraulic chamber 23 is referred to as a first hydraulic chamber 23 and the second hydraulic chamber 25 is referred to as a second hydraulic chamber 25. Both the first hydraulic chamber 23 and the second hydraulic chamber 25 are filled with hydraulic oil. The first hydraulic chamber 23 and the second hydraulic chamber 25 are connected to the oil path switching valve 19 via hydraulic oil paths 22 and 24 that supply hydraulic oil to and discharge hydraulic oil from each. A hydraulic pressure source 21 is connected to the oil path switching valve 19 via a hydraulic oil path 26. A control device 47 is also connected to the oil passage switching valve 19, and the oil passage switching valve 19 is controlled by a signal from the control device 47.
[0016]
In the actuator 11, the oil pressure in the first hydraulic chamber 23 and the second hydraulic chamber 25 is adjusted by controlling the oil passage switching valve 19, and the position of the piston 15 is controlled. As a result, the action portion 17 connected to an object (not shown) to be displaced by the actuator 11 is displaced, and the object is displaced.
[0017]
The piston position detection device 10 includes a movable portion 29, a cap portion 27, and an elastic member 45 that urges the movable portion 29 toward the top surface of the piston 15. The movable portion 29 is located on the side opposite to the end surface (hereinafter referred to as “acting portion side end surface”) on the side where the acting portion 17 of the actuator 11 projects from the casing 13 (hereinafter referred to as “acting portion side end surface”). It is a rod-shaped member that is disposed in an end surface (hereinafter referred to as “non-acting portion side end surface”) through a hole 31 provided in the casing 13 and having one end in contact with the top surface of the piston 15.
[0018]
The cap part 27 covers the hole 31 and includes the movable part 29 therein and is attached to the casing 13. The cap portion 27 can be attached to the casing 13 by, for example, a detachable fastening means such as a screw. The cap portion 27 is preferably attached by applying a sealing means so that hydraulic fluid does not leak from between the cap portion 27 and the casing 13.
[0019]
In the piston position detection device 10, as shown in FIG. 1, holes 33 and 35 are provided at positions corresponding to the holes 31 provided in the casing 13 on the actuator side surface (bottom surface) of the cap portion 27. Is provided. The hole 33 is provided in the center so that the movable part 29 can be passed therethrough, and the peripheral part of the hole 33 constitutes a support part that slidably supports the movable part 29. On the other hand, a plurality of holes 35 are preferably provided around the hole 33 (see FIG. 2A) so that the hydraulic oil can freely move between the first hydraulic chamber 23 and the cap portion 27, A hydraulic pressure difference generated in the first hydraulic chamber 23 and the cap portion 27 is reduced. The shape of the hole provided in the bottom surface of the cap part 27 is such that at least a part of the peripheral part of the hole constitutes a support part that slidably supports the movable part 29 and operates through the hole. Any other shape may be used as long as the oil can freely move in the first hydraulic chamber 23 and the cap portion 27. For example, it may have a shape like the hole 34 shown in FIG. 2B, and in this case, a portion indicated by 36 constitutes the support portion. Further, it is desirable that the area of the hole 34 or the hole 35 provided for the purpose of allowing the hydraulic oil to freely move in the first hydraulic chamber 23 and the cap portion 27 is larger.
[0020]
In the piston position detection device 10, the elastic member 45 is configured by a spring 45 having one end attached to the cap portion 27 and the other end attached to the movable portion 29. The movable portion 29 is urged toward the top surface of the piston 15 by the action of the spring 45 so that the contact between the movable portion 29 and the piston 15 is maintained, and the movable portion 29 is moved to the piston 15. 15 in conjunction with displacement.
[0021]
The piston position detecting device 10 further has a movable part position detecting means for detecting the position of the movable part 29. In the piston position detection device 10, the movable part position detection means includes a known potentiometer 43 including a contact 37, a resistance wire 39, a voltage sensor, and the like. In the piston position detection device 10, the contact 37 is attached to the movable portion 29, and the resistance wire 39 is attached to the inside of the cap portion 27 so as to contact the contact 37. Here, the contact 37 and the movable part 29 are electrically insulated.
As the movable part position detecting means, a known non-contact type position detecting means in which the movable part 29 is made of metal and the position of the movable part 29 is detected from a change in magnetic field due to the movement or an induced current may be used. Good.
[0022]
With the above configuration, when the piston position detection device 10 is used, the position of the piston 15 is detected as follows. That is, when the oil passage switching valve 19 is controlled by a signal from the control device 47 and the hydraulic pressure in the first hydraulic chamber 23 and the second hydraulic chamber 25 is changed, the piston 15 is displaced. At this time, the movable portion 29 is maintained in contact with the piston 15 by the action of the spring 45, so that the movable portion 29 is displaced in conjunction with the piston 15. Therefore, it is possible to detect the position of the piston 15 by detecting the position of the movable part 29, and the position of the movable part 29 can be detected by the potentiometer 43 which is a movable part position detecting means. Thus, this piston position detection apparatus 10 is intended to detect the position of the piston 15 by detecting the position of the movable portion 29. The detection result of the piston position is sent to the control device 47, and the oil passage switching valve 19 is controlled again based on the detection result, so that the first hydraulic chamber 23 and the second hydraulic pressure are adjusted so that the piston 15 becomes a desired position. The working oil pressure in the chamber 25 may be readjusted.
[0023]
As is apparent from the above description, the piston position detection device 10 is attached to the side opposite to the action part side of the actuator 11 (that is, the end face on the non-action part side). In general, the actuator 11 as described above performs the actuator function, and therefore, the action portion side is directed to a device to which the actuator 11 is attached (that is, a device having an object to be displaced by the actuator 11). Therefore, when the piston position detecting device is also attached to the action portion side, various attachment restrictions are imposed and maintenance inconvenience occurs. However, when it is mounted on the side opposite to the action part side as in the present piston position detecting device 10, there are few restrictions on mounting, the mounting itself is easy, and maintenance after mounting can be easily performed. it can.
[0024]
Further, the piston position detection device 10 can be manufactured completely separately from the actuator 11 due to its configuration, and even a hole 31 having a predetermined size is provided at a predetermined position of the casing 13 of the actuator 11. In this case, it can be installed later. In particular, it can be easily replaced even in the case of a failure or the like. Moreover, in this piston position detection apparatus 10, since the movable part 29 cannot be fixedly attached to the piston 15, the degree of freedom of attachment increases and attachment is easy.
[0025]
Further, the present piston position detection device 10 is intended to detect the position of the piston 15 by detecting the position of the movable portion 29, and the position is actually detected by the potentiometer 43. It is the movable part 29 contained in. For this reason, for example, the fine adjustment necessary for measuring the position of the movable portion 29 by the potentiometer 43 which is a position measuring means, such as adjustment of the relative position of the contact 37 and the resistance wire 39, is performed by the piston position detection device 10. This can be done at the manufacturing stage. Therefore, the piston position detection device 10 does not require such fine adjustment when attached to the actuator 11, and can be easily attached in a short time. On the other hand, in the piston position detection device of the type that directly detects the position of the piston, adjustment of the relative position between the position detection means and the piston is required and the mounting accuracy is required when mounting to the actuator. And may take time to install.
[0026]
Further, in the present piston position detection device 10, a hole 35 is provided on the bottom surface of the cap portion 27 as a means for reducing the hydraulic pressure difference generated between the first hydraulic chamber 23 and the cap portion 27. Contributes to detection.
That is, when the piston position detection device 10 is attached, the bubbles 49 may remain in the cap portion 27. In such a case, if there is no hole 35 and the movement of the hydraulic oil between the first hydraulic chamber 23 and the cap portion 27 is performed only from the gap between the movable portion 29 and the hole 33, the operation is performed. Since the movement of the oil is not free, a hydraulic pressure difference is generated between the first hydraulic chamber 23 and the cap portion 27, and the movable portion 29 may be separated from the piston 15 and pushed into the cap portion 27 so as to crush the bubbles 49. is there. This is particularly likely to occur when the pressure in the first hydraulic chamber 23 suddenly increases due to the piston 15 being displaced to the lowest position in FIG. Since the piston position detection device 10 is intended to detect the position of the piston 15 by detecting the position of the movable portion 29, if the movable portion 29 moves away from the piston 15 in this way, the piston 15 is accurately detected. The position cannot be detected.
[0027]
On the other hand, when there is the hole 35, the hydraulic oil can freely move in the first hydraulic chamber 23 and the cap portion 27, so that the hydraulic pressure difference generated between the first hydraulic chamber 23 and the cap portion 27 is reduced. Is done. As a result, the movable portion 29 is prevented from moving away from the piston 15, and the position of the piston 15 can be accurately detected.
If the inside of the cap part 27 is completely filled with hydraulic oil, the movable part 29 will not move away from the piston 15 even if a pressure difference occurs, but it is difficult to completely eliminate bubbles from inside the cap part 27. It is.
[0028]
In the piston position detection device 10, the peripheral portion of the hole 33 provided on the bottom surface of the cap portion 27 constitutes a support portion that supports the movable portion 29 so as to be slidable. As a result, the movable portion 29 can stably slide and move within a predetermined trajectory, which is preferable for accurately detecting the position of the movable portion 29. That is, for example, when the position of the movable portion 29 is detected by the potentiometer 43 as in the piston position detection device 10, the movable portion 29 stably slides and moves within a predetermined track, thereby causing contact. Stable contact between the child 37 and the resistance wire 39 is obtained, and the accuracy of detecting the position of the movable portion 29 is improved. Further, even when a non-contact type position detecting means using a change in a magnetic field or the like is used as the movable part position detecting means, the movable part 29 is slid and moved stably within a predetermined trajectory. The position can be detected.
[0029]
As described above, the present piston position detection device 10 detects the position of the piston 15 by detecting the position of the movable part 29. Therefore, if the detection accuracy of the movable part position is improved, the piston position The detection accuracy is improved.
In the example shown in FIG. 1, the movable oil 29 is passed through the hole 33 whose peripheral part forms a support part for the movable part 29, and in the first hydraulic chamber 23 and the cap part 27. Is provided on the bottom surface of the cap portion 27, and the casing 13 is provided with a large hole 31 including positions corresponding to these holes 33, 35. Conversely, holes corresponding to the holes 33 and 35 may be provided in the casing 13, and holes corresponding to the holes 31 may be provided on the bottom surface of the cap portion 27. Further, holes corresponding to the holes 33 and 35 may be provided on both the bottom surface of the cap portion 27 and the casing 13 so as to correspond to each other.
[0030]
Further, in the present piston position detection device 10, the potentiometer 43 is used as the movable portion position detection means, whereby the movable portion position detection means is configured simply and inexpensively, and the piston position detection device can be easily attached and the piston position detection can be performed. The cost of the apparatus 10 is reduced. That is, in the case of using the non-contact type position detecting means as described above, in general, the cost is higher than that in the case of using the potentiometer 43, and higher mounting accuracy is required.
[0031]
In the piston position detection device 10 shown in FIG. 1, the movable portion 29 is not fixedly coupled to the piston 15. However, the present invention is not limited to this, and can be moved by screwing, for example. The portion 29 may be fixedly coupled to the piston 15 and the spring 45 that is an elastic member may be omitted. However, in this case, the installation is somewhat complicated as compared with the piston position detection device 10 shown in FIG.
[0032]
Further, the actuator 11 in the example shown in FIG. 1 has hydraulic chambers on the top surface side and the bottom surface side of the piston 15, respectively, and controls the position of the piston 15 by adjusting the hydraulic pressure of each hydraulic chamber. However, the piston position detection device of the present invention can also be applied to actuators having other configurations. For example, the actuator 11 of the example shown in FIG. 1 does not have the second hydraulic chamber 25, but instead has a spring that biases the piston 15 upward in FIG. The present invention can also be applied to an actuator of the type that controls the position of the piston only by adjusting the hydraulic pressure (hydraulic oil supply / discharge) in the hydraulic chamber (first hydraulic chamber 23) provided in the cylinder.
[0033]
【The invention's effect】
As described above, according to the present invention, there is provided a piston position detection device that is attached to the side opposite to the action portion side of the hydraulic actuator and that is easy to mount .
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a hydraulically operated actuator provided with a piston position detecting device according to an embodiment of the present invention.
FIG. 2 is a diagram showing a shape of a hole provided in a bottom surface of a cap portion of the piston position detecting device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Piston position detection apparatus 11 ... Hydraulic pressure actuator 13 ... Casing 15 ... Piston 17 ... Action part 19 ... Oil path switching valve 23 ... 1st hydraulic pressure chamber (1st hydraulic pressure chamber)
25 ... Second hydraulic chamber (second hydraulic chamber)
27: Cap part 29 ... Movable part 43 ... Movable part position detecting means (potentiometer)
45. Elastic member (spring)
47. Control device

Claims (3)

A hydraulic actuator that controls the position of a piston slidably disposed in a casing by adjusting the hydraulic pressure in the hydraulic chamber, and acts on an object to be displaced by the hydraulic actuator. part and the action part side end surface acting portion projects from said casing is, in the piston position detector for detecting the piston position of the hydraulic operating actuator and a non-acting portion side end surface of the opposite side of the acting portion side end surface Yes ,
A movable part that is disposed in contact with the piston without being attached to the piston, penetrating through a hole provided in the casing of the hydraulic actuator at the non-acting part side end surface;
Contact maintaining means for maintaining the contact between the movable portion and the piston so that the movable portion is displaced in conjunction with the piston, and the movable portion is attached toward the top surface of the piston. Contact maintaining means including an elastic member
A cap portion that covers the hole provided in the casing of the hydraulic actuator at the non-acting portion side end surface, includes the movable portion inside, and is attached to the casing of the hydraulic actuator;
Movable part position detecting means for detecting the position of the movable part;
A piston position detecting device for detecting the position of the piston by detecting the position of the movable part ,
Furthermore, it has means for reducing the hydraulic pressure difference between the hydraulic pressure chamber and the cap part, and the cap part has support means for slidably supporting the movable part. , Piston position detection device. 2. The piston position detecting device according to claim 1, wherein the hydraulic pressure difference reducing means is constituted by a hole communicating the hydraulic pressure chamber and the cap portion. 3. The piston position detecting device according to claim 1, wherein the movable part position detecting means includes a potentiometer.

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