JP2000234603A - Stroke sensor mounting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a stroke sensor mounting strength while reducing a production cost. SOLUTION: The structure includes a sensor holder 9 being fitted in a cylinder head 2 that is screwed on a cylinder tube 1 while supporting a stroke sensor 4, a plate 18 put between the cylinder head 2 and cylinder tube 1, multiple bolts 17 drawing the sensor holder 9 toward the plate 18 with the cylinder head 2 interposed therebetween, a pipe part 6 projecting from a circumference of the cylinder tube 1 and a notch 33 to prevent rotation of the plate 18 against the pipe part 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulic cylinder,
For example, the present invention relates to a mounting structure of a stroke sensor for detecting a stroke amount of a hydraulic cylinder or the like.

[0002]

2. Description of the Related Art In a hydraulic cylinder having a magnetic scale formed on a piston rod, a stroke sensor facing the magnetic scale is attached to one end of a cylinder tube. Normally, the magnetic scale is formed only on one side, not the entire circumference of the piston rod 3, and therefore, the mounting position of the stroke sensor is limited to the rotational position facing the magnetic scale.

Conventionally, as this type of stroke sensor mounting structure, for example, disclosed in Japanese Utility Model Publication No. 6-40327, as shown in FIG. 4, a cylinder head 2 through which a piston rod 3 is slidably penetrated is provided. There is provided a sensor holder 9 screwed to one end of the cylinder tube 1 and fitted to one end of the cylinder head 2 to support the magnetic sensor 14. The sensor holder 9 is fastened to the cylinder head 2 via a plurality of set screws 12, and is positioned in the rotational direction with respect to the cylinder tube 1 via a positioning plate 7 which engages with a tube 6 protruding from the cylinder tube 1. Will be

[0004] Further, as disclosed in Japanese Utility Model Publication No. 6-39123, a cylinder head 2 for slidably penetrating a piston rod 3 is screwed to one end of a cylinder tube 1 as shown in FIG. The sensor holder 9 is fitted to one end of the cylinder head 2 and supports the magnetic sensor 14. A bracket 16 is fixed to the outer periphery of the cylinder tube 1 by welding, and the sensor holder 9 is fastened to the bracket 6 via a plurality of bolts 13 to perform positioning in the axial direction and the rotation direction with respect to the cylinder tube 1.

[0005]

However, in the conventional structure as shown in FIG. 4, the sensor holder 9 has the set screw 12 extending in the radial direction of the piston rod 3.
, The sensor holder 9 is rattled when an external impact is received, and the sensor holder 9 may rotate. Further, there is a problem that the binding force in the cylinder axis direction is poor. If the sensor holder 9 rotates in this way, accurate position stroke detection cannot be performed.

In the conventional structure shown in FIG. 5, since the sensor holder 9 is fastened to the bracket 6 via a bolt 13 extending in the axial direction of the piston rod 3, the sensor holder 9 receives an external impact. Although the rattle is unlikely to occur, the structure in which the bracket 6 is fixed to the outer periphery of the cylinder tube 1 by welding has a problem that the manufacturing cost increases.

The present invention has been made in view of the above problems, and has as its object to increase the mounting strength of a stroke sensor and reduce manufacturing costs.

[0008]

A first invention comprises a piston rod slidably supported on a cylinder tube via a cylinder head, and a stroke sensor for reading a scale formed on the piston rod. The present invention is applied to a stroke sensor mounting structure for fixing a sensor at a predetermined rotation position with respect to a cylinder tube.

A screwing means for screwing the cylinder head to the cylinder tube; a sensor holder for supporting the stroke sensor and fitting to the cylinder head; a plate interposed between the cylinder head and the cylinder tube;
A plurality of bolts for pulling the sensor holder to the plate with the cylinder head interposed therebetween, a projection protruding from the outer periphery of the cylinder tube, and positioning means for locking the plate in the rotation direction with respect to the projection.

According to a second aspect of the present invention, in the first aspect, a notch for engaging with the projection is formed on the plate as positioning means.

According to a third aspect of the present invention, in the first or second aspect, a projection projects from the outer periphery of the cylinder tube to guide the working fluid.

[0012]

In the first invention, a plate is interposed between the cylinder head and the cylinder tube,
The structure including a plurality of bolts that draws the sensor holder to the plate with the cylinder head in between makes it possible to increase the force that restrains the sensor holder in the axial direction of the piston rod, and causes rattling of the sensor holder due to an external impact Can be prevented.

By engaging the plate with a projection protruding from the outer periphery of the cylinder tube, the mounting position of the stroke sensor is limited with respect to the rotation direction of the cylinder tube. Can correctly confront the magnetic scale.

Further, there is no need to fix a plate or the like to the cylinder tube by welding, so that manufacturing costs can be reduced.

According to the second aspect of the present invention, the notch for engaging the projection is formed on the plate as the plate positioning means, so that the increase in the number of parts can be suppressed and the assembling can be facilitated to increase the productivity.

According to the third aspect of the present invention, the protrusion engaging with the plate is formed as a pipe portion for projecting from the outer periphery of the cylinder tube to guide the working fluid, thereby suppressing an increase in the number of parts and simplifying the structure.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the hydraulic cylinder includes a piston rod 3 slidably supported on a cylinder tube 1 via a cylinder head 2, and a piston (not shown) is connected to one end of the piston rod 3. . A seal ring 24 is provided between the cylinder head 2 and the piston rod 3.
And an oil chamber 2 defined in the cylinder tube 1
5 is sealed.

A tube 6 protruding from the outer periphery of the cylinder tube 1 is provided. The tube 6 has a base end fixed to the cylinder tube 1 and communicates with the oil chamber 25 via a pipe (not shown) connected to the end thereof. Hydraulic oil (working fluid) is introduced.

In order to detect the stroke amount of the hydraulic cylinder, a magnetic scale is embedded in the piston rod 3 in the axial direction at a predetermined pitch, and a stroke sensor 4 for reading the magnetic scale is attached to one end of the cylinder tube 1. ing. The stroke sensor 4 includes a magnetic sensor 14 that detects a change in a magnetic field facing the magnetic scale. The magnetic sensor 14 generates an output wave synchronized with the scale pitch as the piston rod 3 moves.

The sensor holder 9 for supporting the magnetic sensor 14
The main body of the stroke sensor 4 is fastened to the sensor holder 9 via four bolts 35. The magnetic sensor 14 is interposed in the sensor holder 9 via a sleeve 26, and is supported so as to be slidable in the radial direction of the piston rod 3. A spring 27 for urging the magnetic sensor 14 toward the piston rod 3 via a sleeve 26 is provided, and a spacer 28 for maintaining a constant clearance between the magnetic sensor 14 and the piston rod 3 is interposed.

As a mounting structure of the stroke sensor 4, the sensor holder 9 includes a plate 18 on the cylinder head 2.
Are connected via The sensor holder 9 is formed in a frame shape through which the piston rod 3 penetrates, and the tip end portion 22 of the cylinder head 2 is fitted to the sensor holder 9 via a seal ring 21. The cylinder head 2 has an annular projection 23 sandwiched between the sensor holder 9 and the plate 18.
When the plate 18 is fastened to the sensor holder 9 via four bolts 17, the annular convex portion 23 is sandwiched between the plate 18 and the sensor holder 9, and the sensor holder 9 is connected to the cylinder head 2 via the plate 18. Fixed.

Each of the four bolts 17 has a function of attracting the plate 18 and the sensor holder 9 to each other. FIG.
As shown in FIG. 3, each of the four bolts 17 is
, And extends in the axial direction of the piston rod 3, penetrates through bolt holes 34 formed at the four corners of the plate 18, and is screwed into each screw hole formed at the four corners of the sensor holder 9.

A cylinder tube 1 is screwed and connected to one end of the cylinder head 2. In other words, as a screwing means for screwing the cylinder head 2 to the cylinder tube 1, a male screw is formed on the outer periphery of the cylinder head 2, while a female screw is formed on the inner periphery of the cylinder tube 1. I have.

Incidentally, the magnetic scale is formed not on the entire circumference of the piston rod 3 but on only one side surface.
4 needs to be limited to the rotational position facing the magnetic scale.

In order to limit the mounting position of the stroke sensor 4 with respect to the rotation direction of the cylinder tube 1, the plate 18 serves as a positioning means for locking the plate 18 in the rotation direction with respect to the pipe portion 6 protruding from the outer periphery of the cylinder tube 1. Is formed with a notch 33 that engages with the tube portion 6.

The plate 18 has a joining flange 32 with respect to the annular projection 23 of the cylinder head 2 and a strip-shaped engaging portion 31 which is bent from the joining flange 32 along the cylinder tube 1. A notch 33 is formed at the tip of the portion 31. The notch 33 allows the engaging portion 3
The tip of 1 has a forked shape so as to sandwich the tube 6,
The plate 18 is positioned in the rotation direction with respect to the cylinder tube 1.

The piston rod 3 is positioned relative to the cylinder tube 1 in the rotational direction.

The operation is described below, with the above configuration.

The cylinder head 2 is held between the sensor holder 9 and the plate 18, and the plate 18 is
The structure in which the bolt 17 to be fastened to the piston rod 3 is arranged in the axial direction of the piston rod 3 makes the sensor holder 9
The force for restraining the sensor holder 9 in the axial direction is increased, and it is possible to prevent the sensor holder 9 from rattling due to an external impact.

By engaging the notch 33 of the plate 18 with the pipe 6 projecting from the outer periphery of the cylinder tube 1, the mounting position of the stroke sensor 4 is limited in the rotation direction of the cylinder tube 1, and the magnetic sensor 14
Faces the magnetic scale embedded in one side surface of the piston rod 3, so that the magnetic sensor 14 housed in the sensor holder 9 can correctly face the magnetic scale of the piston rod 3.

The structure in which the notch 33 that engages with the pipe portion 6 is formed in the plate 18 as the positioning means of the plate 18 can suppress an increase in the number of parts, facilitate assembly, and increase productivity.

Further, the protrusion engaging with the plate 18 protrudes from the outer periphery of the cylinder tube 1 to form the pipe portion 6 for guiding the working fluid, thereby suppressing an increase in the number of parts.

Further, it is not necessary to fix the plate 18 and the like to the cylinder tube 1 by welding, so that the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and is a cross-sectional view of a hydraulic cylinder taken along line AA of FIG.

FIG. 2 is a plan view of the hydraulic cylinder.

FIG. 3 is a front view of the plate.

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

FIG. 5 is a sectional view of a hydraulic cylinder showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder tube 2 Cylinder head 3 Piston rod 4 Stroke sensor 6 Tube part 9 Sensor holder 17 Bolt 18 Plate 33 Notch

Claims (3)

[Claims] A piston rod slidably supported on a cylinder tube via a cylinder head; and a stroke sensor for reading a scale formed on the piston rod. In a stroke sensor mounting structure fixed at a predetermined rotational position, a screwing means for screwing the cylinder head to the cylinder tube; a sensor holder supporting the stroke sensor and fitting to the cylinder head; And a plate interposed between the cylinder tube and the cylinder tube; a plurality of bolts for pulling the sensor holder to the plate with the cylinder head interposed; a projection protruding from the outer periphery of the cylinder tube; Position to lock in the rotation direction Stroke sensor mounting structure, wherein the means decided, further comprising a. 2. The stroke sensor mounting structure according to claim 1, wherein a notch is formed in said plate as said positioning means so as to engage with said projection. 3. The stroke sensor mounting structure according to claim 1, wherein said projection is a pipe portion projecting from an outer periphery of said cylinder tube to guide a working fluid.