JP2559746Y2 - Fluid pressure cylinder device - Google Patents

Description

[Detailed description of the invention]

[0001]

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

[0002]

FIG. 4 is a sectional view of a conventional hydraulic cylinder 80. As shown in FIG. The hydraulic cylinder 80 includes a cylinder tube 81, a rod cover 82, a head cover 83, a piston 84, a piston rod 85, and the like.

A sensor 87 for detecting a stroke position of a piston 84 is attached to the head cover 83. A probe 87a of the sensor 87 is inserted into a shaft hole 86 provided in the piston rod 85, The position is detected by a magnet 88 attached to the device. As such a sensor 87, for example, a non-contact displacement sensor Model GY manufactured by Suntest is used.

[0004] By supplying pressure oil, the piston 8
The probe 87 moves right and left, and the probe 87a moves in and out of the shaft hole 86, and the sensor 87 outputs a signal corresponding to the position of the magnet 88 in the axial direction with respect to the probe 87a.

[0005]

However, in the above-described conventional hydraulic cylinder 80, when the stroke is long, the probe 87a becomes longer because the probe 87a becomes longer, and as shown in FIG. It may come in contact with the inner peripheral surface.

In such a case, if the surface roughness of the inner peripheral surface of the shaft hole 86 is poor or there is a step, the tip of the probe 87a is caught during the retraction operation of the piston rod 85, and the probe 87a is bent. Damage occurs, and in the worst case, the probe 87a is damaged.

Further, depending on the length of the probe 87a,
The hydraulic cylinder 80 may resonate due to vibration of the entire hydraulic cylinder 80 and bend significantly, and may be damaged from its root. In view of the above problems, an object of the present invention is to provide a hydraulic cylinder device capable of reliably detecting a stroke position of a piston without breaking a sensor probe even in a long stroke. .

[0008]

According to a first aspect of the present invention, there is provided an apparatus for detecting a stroke of a piston, wherein a sensor probe attached to a cylinder cover is provided on a piston rod to detect a stroke position of the piston. A fluid pressure cylinder device configured to be inserted into a given shaft hole, wherein the cylinder cover has an inner diameter larger than an outer diameter of the sensor probe and a greater rigidity than the sensor probe, The sensor probe covers the entire length of the sensor probe in the axial direction, and is provided with a protection pipe that can be inserted into the shaft hole.

[0009] In the device according to the invention of claim 2, the protection pipe is provided at a position close to the cylinder cover.
A communication hole communicating the inner surface and the outer surface is provided.

[0010] In the device according to the third aspect of the present invention, the piston rod has a sliding portion that slides in the axial direction with the outer peripheral surface of the protection pipe, and an inner space of the shaft hole communicating with the cylinder chamber. And a bypass passage is provided.

[0011]

The sensor probe is covered with a protective pipe to reduce play and does not directly contact the inner peripheral surface of the shaft hole.

In addition, the volume of the internal space of the shaft hole changes with the movement of the piston. At this time, the clearance between the protection pipe and the shaft hole, the communication hole provided in the protection pipe, or the bypass is provided. Fluid moves through the passage.

In the present invention, the piston rod may include a piston.

[0014]

1 is a sectional view of a hydraulic cylinder 1 according to the present invention. The hydraulic cylinder 1 includes a cylinder tube 11, a rod cover 12, a head cover 13, a piston 14, a piston rod 15, and the like.

A sensor 20 for detecting the stroke position of the piston 14 is attached to the head cover 13, and a probe 21 of the sensor 20 is inserted into a shaft hole 16 provided in the piston rod 15, The stroke position is detected by a magnet 18 attached to the motor.

The head cover 13 is provided with a protective pipe 19 having an inner diameter larger than the outer diameter of the probe 21 and capable of being inserted into the shaft hole 16. The protection pipe 19 is made of a nonmagnetic material such as stainless steel, and has sufficient rigidity so as not to cause buckling or large bending due to its own weight.
The head cover 13 is connected and fixed to the head cover 13 by, for example, screws.

A magnet holder 17 for supporting the above-mentioned magnet 18 is screwed and fixed to the end face of the piston 14. The magnet 18 is fixed with an adhesive or the like.

A clearance is provided between the magnet holder 17 and the protection pipe 19 to allow oil in the shaft hole 16 to flow when the piston 14 moves. Instead of this clearance, a magnet is used. A connection hole for bypass may be provided in the holder 17 or the protection pipe 19.

Reference numerals 31 and 32 denote ports, and reference numerals 33 and 34 denote packings. According to the hydraulic cylinder 1 described above, the piston 14 and the piston rod 15 reciprocate left and right by supplying pressure oil from the ports 31 and 32. At that time, the probe 21 is activated by the magnetic field of the magnet 18, and the sensor 20 outputs a signal corresponding to the position of the piston 14. Since the probe 21 is covered by the protective pipe 19 and has little play,
There is no contact with the inner peripheral surface of the shaft hole 16 or a moving member such as the magnet holder 17 and therefore the probe 21
When the hydraulic cylinder 1 is vibrated, the piston 21 does not bend or break significantly, and the piston 14 is reliably prevented from being damaged.
Can be detected.

FIG. 2 is a sectional view showing a main part of a hydraulic cylinder 2 according to another embodiment of the present invention, and FIG. 3 is a sectional view showing a distal end portion of a piston rod 15 of the hydraulic cylinder 2 in FIG. Note that portions having the same functions as the components described in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

In the hydraulic cylinder 2, the protective pipe 1
9 is screwed into the head cover 13 and fixed.
The magnet holder 17 has a sliding portion 42 having a small clearance with respect to the outer diameter of the protection pipe 19, and the sliding portion 22 is slidable in the axial direction with the outer peripheral surface of the protection pipe 19.

In order to make the inner peripheral surface of the shaft hole 16 smooth, a sliding pipe 41 such as a cold drawn material is attached to the inner periphery of the piston rod 15. Are shaft holes 16. A clearance through which oil can flow is provided between the sliding pipe 41 and the hole 47 of the piston rod 15, and an air vent 46 for venting air is provided at a distal end thereof. In addition, 44 and 45 are communication holes provided in the sliding pipe 41, and 15a is a cap for closing the tip of the piston rod 15.

The protection pipe 19 is provided with a communication hole 43 for communicating the inner surface and the outer surface thereof. Communication hole 43
Are provided at a plurality of positions in the axial direction such as positions near both ends of the protective pipe 19 and an intermediate position, and two positions in the circumferential direction at the same axial position.

The magnet holder 17 is provided with a plurality of bypass passages 47 for communicating the internal space 51 of the shaft hole 16 with the cylinder chamber 53. According to the hydraulic cylinder 2 described above, when the piston 14 moves, the sliding portion 42 slides on the outer peripheral surface of the protection pipe 19, so that the protection pipe 19 is supported by the magnet holder 17 even when the stroke is extremely long. Thus, the occurrence of bending and vibration is prevented.

The oil flowing between the cylinder chamber 53 and the internal space 51 flows smoothly through the communication hole 43 or the bypass passage 47, and no back pressure is generated. The air accumulated in the internal space 51 can be easily discharged by the air vent 46.

In the above embodiment, the piston rod 1
The sliding pipe 41 may be omitted when the inner peripheral surface of the fifth hole 47 is finished smoothly. Communication holes 43, 44, 4
The position, number, size, and the like of 5 or the bypass passage 47 can be variously changed. The structure of the hydraulic cylinder 1 can be variously changed in accordance with the gist of the present invention.

[0027]

According to the present invention, the stroke position of the piston can be reliably detected without damaging the sensor probe even in the case of a long stroke.

According to the second aspect of the present invention, the fluid passes through the communication hole with the movement of the piston, so that the generation of the back pressure can be effectively prevented. According to the third aspect of the present invention, even when the stroke is extremely long, the protection pipe is supported by the sliding portion, and the occurrence of bending and vibration is prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic cylinder according to the present invention.

FIG. 2 is a sectional view showing a main part of a hydraulic cylinder according to another embodiment of the present invention.

FIG. 3 is a sectional view showing a distal end portion of a piston rod of the hydraulic cylinder of FIG. 2;

FIG. 4 is a sectional view of a conventional hydraulic cylinder.

[Explanation of symbols]

 1, 2 Hydraulic cylinder (fluid pressure cylinder device) 13 Head cover (cylinder cover) 14 Piston 15 Piston rod 16 Shaft hole 19 Protection pipe 21 Probe (Sensor probe) 42 Sliding part 43 Communication hole 47 Bypass passage 51 Internal space 53 Cylinder chamber

Claims (3)

(57) [Scope of request for utility model registration] 1. A fluid pressure cylinder device, wherein a sensor probe attached to a cylinder cover for detecting a stroke position of a piston is inserted into a shaft hole provided in a piston rod. The cylinder cover has an inner diameter larger than the outer diameter of the sensor probe and has a greater rigidity than the sensor probe, and covers the sensor probe over the entire axial length and can be inserted into the shaft hole. A hydraulic cylinder device comprising a protection pipe. 2. A fluid pressure cylinder device according to claim 1, wherein said protection pipe is provided with a communication hole communicating between an inner surface and an outer surface thereof at a position close to said cylinder cover. . 3. The piston rod is provided with a sliding portion which slides in an axial direction with an outer peripheral surface of the protection pipe, and a bypass passage for communicating an inner space of the shaft hole with a cylinder chamber. 3. The hydraulic cylinder device according to claim 2, wherein: