JP2018071601A - Fluid cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic cylinder including a magnetostriction sensor, which is excellent in mountability for a required external device.SOLUTION: A hydraulic cylinder 10 includes a magnetostriction sensor 51 configured to detect a permanent magnet 21 on a piston 12 to detect a position of the piston 12. At one end of a cylinder tube 11, a head unit 22 is provided, and in the head unit 22, a concave mounting part 43 is provided, which is opened toward the cylinder tube 11 side. Inside the mounting part 43, a sensor body 52 is provided, and seated on a bottom part 57 of the mounting part 43.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fluid cylinder such as a hydraulic cylinder, and more particularly to a fluid cylinder having a sensor for detecting the position of a piston.

Patent Document 1 discloses a fluid cylinder having a magnetostrictive sensor for detecting the position of a piston.
In the fluid cylinder disclosed in Patent Document 1, the sensor body of the magnetostrictive sensor is mounted from the opening on the base end surface opposite to the cylinder tube with respect to the sensor mounting portion of the bottom member on the head side of the fluid cylinder. Has been. In Patent Document 1, a bottom member is disposed on the proximal end side of the cylinder tube, and a member called a cylinder head is disposed on the distal end side of the cylinder tube.

Japanese Patent Laying-Open No. 2015-3298

  Therefore, in the configuration of Patent Document 1, in order to allow the sensor body to be mounted on the sensor mounting portion, the bottom member on the cylinder head side has an insertion hole that opens on the base end surface on the opposite side of the cylinder tube. It is necessary to form and mount the sensor body through the insertion hole. The insertion hole requires an inner diameter larger than the outer diameter of the sensor body in order to allow the sensor body to be inserted. Therefore, due to the presence of the insertion hole, it becomes difficult to form a clevis or a thin male screw on the end surface of the bottom member constituting the head unit. In such a case, the cylinder cannot be mounted on a required device. There is a fear.

  An object of the present invention is to solve the above-described problems and provide a fluid cylinder excellent in mountability.

  In order to achieve the above object, in the present invention, a head unit is provided at one end of a cylinder tube in a fluid cylinder provided with a sensor for detecting the position of the piston by detecting a magnet provided in the piston. In addition, a sensor main body is provided inside the head unit, a magnetostrictive line for sending an excitation pulse from the sensor main body is provided at the center position in the piston rod, and the head unit is attached to the cylinder tube. The sensor main body is mounted in the mounting portion, and the sensor main body is seated on the bottom of the mounting portion.

  In the above configuration, since the sensor main body of the sensor that opens to the cylinder tube side of the head unit is mounted in a state of being seated on the bottom of the mounting portion, the inner diameter of the sensor unit that is larger than the outer diameter of the sensor main body is inserted. There is no need to provide a hole, the restriction on the shape of the mounting portion of the head unit is reduced, and the mountability of the fluid cylinder to the required device is improved.

  According to the present invention, a fluid cylinder excellent in mountability can be obtained even in a fluid cylinder in which the sensor body is mounted inside the head unit.

Sectional drawing of the fluid cylinder of 1st Embodiment. The partial expanded sectional view of the fluid cylinder of 1st Embodiment. The top view of the fluid cylinder of 1st Embodiment. The side view of the fluid cylinder of 1st Embodiment. Sectional drawing of the fluid cylinder of 2nd Embodiment. The partial expanded sectional view of the fluid cylinder of 2nd Embodiment. The top view of the fluid cylinder of 2nd Embodiment. The side view of the fluid cylinder of 3rd Embodiment. Sectional drawing of the fluid cylinder of 3rd Embodiment.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described based on the drawings of FIGS.
As shown in FIGS. 1 and 2, a piston 12 is inserted into a cylinder tube 11 of the hydraulic cylinder 10, and the piston 12 has a piston head 13 and a cylindrical shape fixed to the piston head 13. And a piston rod 16. Then, the piston 12 is moved so that the piston rod 16 protrudes from the tip of the cylinder tube 11. A rod side port 17 is disposed at the tip of the cylinder tube 11, and hydraulic oil as a working fluid enters and exits between the rod side oil chamber 18 and an external pipe (not shown) via the rod side port 17. .

An annular permanent magnet 21 is provided in the piston head 13 at a position near the inner peripheral surface of the cylinder tube 11.
A head unit 22 having a quadrangular prism shape is fixed to the head side (right side in FIG. 1) of the cylinder tube 11. An annular fixing member 23 and an annular port member are sequentially attached to the head unit 22 from the rod side. 24 and a bottomed annular bottom member 25 are provided. 3 and 4, a bolt 28 passing through the insertion hole 27 of the fixing member 23 and the port member 24 is screwed into a female screw 29 of the bottom member 25, and the fixing member 23 and the port are connected by the bolt 28. The member 24 and the bottom member 25 are integrally fastened.

  As shown in FIGS. 1 and 2, a fixing ring 32 made of a metal wire is fitted in an annular groove 31 on the outer periphery on the head side of the cylinder tube 11. An annular inclined surface 33 on the inner periphery of the fixing member 23 is engaged with the fixing ring 32, and movement of the head unit 22 toward the head side is prevented by this engagement.

  The port member 24 has flange portions 34 on the rod side and the head side, and the rod side flange portion 34 is fitted to the outer peripheral surface of the cylinder tube 11 via the packing 35, A flange portion 34 is fitted to the outer peripheral surface of the flange portion 36 of the bottom member 25 via a packing 35. The rod-side end surface of the rod-side flange portion 34 is joined to the fixing member 23, and the head-side flange portion 34 is joined to the rod-side step surface 37 of the bottom member 25.

  A protrusion 38 is formed on the inner periphery between both flange portions 34 of the port member 24, and the rod side surface thereof is a restriction surface 39 that forms the head side moving end of the piston head 13. The rod-side moving end of the piston head 13 is regulated by a regulating member 40 inside the tip of the cylinder tube 11. In the portion of the protrusion 38, the port member 24 has a head side port 41 penetrating therethrough. The head-side port 41 opens into the head-side oil chamber 42, and hydraulic oil enters and exits between the head-side oil chamber 42 and external piping (not shown) via the head-side port 41.

  A mounting portion 43 facing the head side oil chamber 42 and communicating with the head side oil chamber 42 is recessed on the rod side of the bottom member 25, and the mounting portion 43 includes a large diameter portion 44 on the rod side. And a small-diameter portion 45 on the head side. A sensor main body 52 of the magnetostrictive sensor 51 is accommodated in the large diameter portion 44 and is seated on the bottom 57 of the large diameter portion 44. The magnetostrictive sensor 51 has a pressure-resistant pipe 53 extending from the sensor body 52 toward the rod, and the pressure-resistant pipe 53 is inserted into the piston rod 16. A magnetostrictive wire 54 is inserted into the pressure-resistant pipe 53.

  Then, when an excitation pulse is sent from the sensor body 52 to the magnetostrictive wire 54 and an external magnetic field of the permanent magnet 21 acts on this excitation pulse, a pulse due to mechanical distortion is generated in the magnetostrictive wire 54. The sensor main body 52 receives the distortion pulse, counts the time from the generation of the excitation pulse until the distortion pulse is received, and calculates the position of the permanent magnet 21. Thereby, the absolute position of the piston 12 is detected.

  The head side port 41 is located between the sensor main body 52 and the position where the piston head 13 is regulated by the regulation surface 39, that is, the permanent magnet 21 in a state where the piston 12 is at the immersive end.

  As shown in FIG. 2, a packing 55 that engages with the inner peripheral surface of the large-diameter portion 44 is wound around the outer periphery of the sensor main body 52. When the hydraulic cylinder 10 is assembled on the outer peripheral edge on the head side of the cylinder tube 11 and the outer peripheral edge and inner peripheral edge of the flange portion 36 of the bottom member 25, the packing 35 and 55 of the port member 24 and the sensor body 52 and the cylinder tube 11 are assembled. A chamfer 56 is formed to reduce interference with the tip of the flange portion 36. A wave washer 58 as an urging means is interposed between the protrusion 38 of the port member 24 and the sensor main body 52, and the sensor main body 52 is against the bottom 57 of the large diameter portion 44 by the spring force of the wave washer 58. It is biased in the seating direction.

  As shown in FIG. 1, a cable gland 59 is attached to the outer peripheral surface of the base end portion of the bottom member 25, and a power supply line 60 between the cable gland 59 and the sensor body 52 passes through the small diameter portion 45. . An attachment portion 61 for attaching the hydraulic cylinder 10 to a required external device is integrally formed on the end surface of the bottom member 25 on the head side. In the present embodiment, the attachment portion 61 is constituted by a male screw.

Next, the operation of the hydraulic cylinder 10 of the first embodiment will be described.
When assembling the hydraulic cylinder 10 of the present embodiment, the fixing member 23 is fitted on the outer periphery of the cylinder tube 11 in which the piston 12 is incorporated, and the fixing ring 32 is fitted in the annular groove 31. 3 is prevented from coming off to the right.

  Thereafter, one flange portion 34 of the port member 24 is fitted to the outer periphery of the cylinder tube 11, and the flange portion 36 of the bottom member 25 is fitted to the other flange portion 34 of the port member 24. At this time, the sensor main body 52 of the magnetostrictive sensor 51 is mounted in advance on the mounting portion 43 of the bottom member 25 and is seated on the bottom portion 57 of the mounting portion 43, and a wave washer 58 is mounted. As the bottom member 25 and the port member 24 and the cylinder tube 11 are assembled, the pressure-resistant pipe 53 of the magnetostrictive sensor 51 is inserted into the piston head 13 and the piston rod 16 in the cylinder tube 11.

  If the bolts 28 are tightened in this state, the fixing member 23, the port member 24 and the bottom member 25 are integrated, and the head unit 22 assembled to the cylinder tube 11 is configured. The head unit 22 is prevented from moving to the head side by the engagement of the fixing ring 32 and the annular inclined surface 33, and by the engagement of the end surface on the head side of the cylinder tube 11 and the protrusion 38 of the port member 24. Movement to the rod side is prevented. Further, the sensor main body 52 of the magnetostrictive sensor 51 is seated in pressure contact with the bottom 57 of the large diameter portion 44 of the mounting portion 43 by the urging force of the wave washer 58. In this state, the hydraulic cylinder 10 is attached to a required external device at the attachment portion 61.

When the piston 12 is moved in the projecting direction or the immersion direction, the moving position of the piston 12 is detected by the action of the magnetostrictive sensor 51.
The first embodiment has the following effects.

  (1) The head unit 22 is provided with a concave mounting portion 43 that opens to the cylinder tube 11 side. The sensor main body 52 is mounted in the mounting portion 43 and the bottom portion of the large-diameter portion 44 of the mounting portion 43. A sensor main body 52 is seated on 57. Therefore, unlike the conventional configuration in which the sensor main body is mounted from the head side end of the head unit, there is no need to provide an insertion hole for passing the sensor main body 52 through the head unit 22, and the head side end of the head unit 22 is not required. There are fewer restrictions on the shape of the part. Accordingly, the flexibility of the shape of the head side end portion of the head unit 22 is increased, and the mounting portion 61 having an appropriate structure can be formed to improve the mountability of the hydraulic cylinder 10 to a required external device.

  (2) Since the sensor main body 52 faces the head-side oil chamber 42, the distance between the sensor main body 52 and the piston head 13 can be shortened, and the overall length of the hydraulic cylinder 10 can be shortened.

  (3) The distance between the piston head 13 and the sensor body 52 is determined by the thickness of the ridge 38 of the port member 24 between the cylinder tube 11 and the bottom member 25, that is, the cylinder axial dimension. Therefore, by selecting the port member 24 having the protrusions 38 having an appropriate thickness, the distance between the sensor main body 52 and the permanent magnet 21 located at the moving end on the head side is set to the shortest time that does not cause sensor malfunction. It can be a distance. Accordingly, the overall length of the hydraulic cylinder 10 can be shortened as described above. In other words, since the head-side port 41 is disposed at a position corresponding to the shortest distance, the overall length of the hydraulic cylinder 10 can be shortened.

  (4) Since the head side port 41 is disposed between the sensor main body 52 and the permanent magnet 21 at the shortest distance that does not cause the above-described sensor malfunction, the total length of the hydraulic cylinder 10 is increased by the arrangement of the head side port 41. The hydraulic cylinder 10 can be shortened by avoiding an increase in length.

  (5) By providing the wave washer 58 that urges the sensor main body 52 in the seating direction with respect to the bottom 57 of the large-diameter portion 44 of the mounting portion 43, the sensor main body 52 can be held in a stable state at a fixed position. The deformation of the main body 52 can be prevented. Therefore, it is possible to accurately detect the position of the piston 12 by the magnetostrictive sensor 51. On the other hand, when the sensor main body 52 is pressed using a screw to seat the sensor main body 52 on the bottom portion 57, the sensor main body 52 becomes loose when the screw is loosened. The main body 52 may be deformed, and in any case, the position of the piston 12 may not be detected accurately.

  (6) Since the bottom member 25 is separate from the port member 24, it is possible to select the bottom member 25 having the mounting portion 43 that matches the size of the sensor body 52, the mounting portion 61 having a required shape, and the like. . Further, it is possible to select a port member 24 having a protrusion 38 having a thickness matching the detection capability of the sensor body 52, that is, a cylinder axial dimension, and a head-side port 41 having an inner diameter matching the oil flow rate per unit time. Therefore, the hydraulic cylinder 10 can flexibly meet various functions and performance requirements.

  (7) In order to shorten the overall length of the hydraulic cylinder 10, it is preferable to incorporate the sensor body 52 so as to face the head-side oil chamber 42. In this configuration, unlike the embodiment, when the cylinder tube 11 and the head unit 22 are integrated, the sensor main body 52 needs to be attached to the head unit 22 through the cylinder tube 11. Therefore, there is a restriction that a cylinder tube 11 having an inner diameter smaller than the outer diameter of the sensor body 52 cannot be used. On the other hand, in this embodiment, since the bottom member 25 having the mounting portion 43 is a separate body, there is no such restriction, and the inner diameter of the cylinder tube 11 is smaller than the outer diameter of the sensor body 52. However, the sensor main body 52 can be attached to the head unit 22.

  (8) Since the bottom member 25 has a prismatic shape, a flat surface is formed on the outer peripheral surface thereof. For this reason, the cable gland 59 can be held on the outer peripheral surface of the bottom member 25 in a stable state.

(Second embodiment)
Next, 2nd Embodiment of this invention is described based on drawing of FIGS.
As shown in FIGS. 5 and 6, in the second embodiment, the fixing member 23 and the fixing ring 32 of the first embodiment are not provided. The port member 24 is fixed to the outer periphery of the cylinder tube 11 by welding. A port hole 71 communicating with the head side port 41 of the port member 24 is formed in the cylinder tube 11. The port hole 71 and the head-side port 41 are disposed at a position facing the shortest distance between the sensor main body 52 and the permanent magnet 21 that has moved to the moving end on the head side so as not to cause a malfunction of the sensor.

  As shown in FIGS. 5, 7 and 8, the bottom member 25 is formed with a flange 72 projecting in the outer peripheral direction. A back plate 73 is attached to the base end of the bottom member 25, and a bolt 76 that passes through the bolt insertion hole 75 of the back plate 73 and the bolt insertion hole 74 of the flange 72 is screwed into the screw hole 77 of the port member 24. The bottom member 25 is fastened to the port member 24 via the back plate 73.

As shown in FIG. 6, a chamfer 56 for avoiding interference with the packing 55 of the sensor main body 52 is formed on the opening edge of the mounting portion 43.
A slope 78 is formed on the inner peripheral surface of the proximal end of the cylinder tube 11, and a step 79 is formed at the opening of the large-diameter portion 44 of the bottom member 25, and an annular shape is formed between the slope 78 and the step 79. A spacer 80 is held. A slope 81 that engages with the slope 78 is formed at the rod side end of the outer periphery of the spacer 80, and a slope 82 is formed at the head side end. A wave washer 58 is interposed between the spacer 80 and the sensor main body 52. The wave washer 58 holds the spacer 80 on the inclined surface 78 of the cylinder tube 11, and the sensor main body as in the first embodiment. 52 is held in a seated state with respect to the bottom 57 of the large diameter portion 44. The retracted end of the piston head 13 is regulated by the end surface of the spacer 80 on the rod side. Therefore, a regulating surface 39 for regulating the immersion end of the piston 12 is formed by the rod-side end surface of the spacer 80. On the rod-side end face of the spacer 80, a groove 83 is formed for avoiding the close contact of the piston head 13 with the spacer 80 and facilitating movement of the piston 12 in the protruding direction.

  In the second embodiment, the power supply line 60 protrudes outside through the hole 84 of the back plate 73. Therefore, the mounting portion 61 of the first embodiment is not provided on the end surface of the bottom member 25. A filler 85 is provided between the bottom of the small diameter portion 45 of the mounting portion 43 and the sensor main body 52. The head unit 22 is attached to a required device via a member (not shown) that holds the back plate 73.

In the present embodiment, substantially the same effects as those of the first embodiment can be obtained, and the following effects can be obtained.
(9) If the spacer 80 is thin, that is, the axial dimension of the hydraulic cylinder 10 is small, the port member 24 can be wrapped with the piston head 13 in the cylinder radial direction. The overall length of the cylinder 10 can be shortened.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG.
In the third embodiment, the port member 24 is welded to the cylinder tube 11 as in the second embodiment. A flange 72 projecting in the outer circumferential direction is formed at the end of the bottom member 25 on the rod side, and the port member 24 and the bottom member 25 are fastened by a bolt 91 that passes through a bolt insertion hole 74 of the flange 72.

A clevis 92 is formed at the rear end of the bottom member 25.
Therefore, in the present embodiment, substantially the same effect as that of the second embodiment can be obtained.

(Example of change)
The present invention is not limited to the above embodiments, and can be embodied in the following manner.

Instead of the wave washer 58 that urges the sensor body 52 in the seating direction, other urging means such as a leaf spring or a rubber-like elastic body is used.
-The present invention is embodied in a pneumatic cylinder or a hydraulic cylinder.

  DESCRIPTION OF SYMBOLS 10 ... Fluid cylinder, 11 ... Cylinder tube, 12 ... Piston, 13 ... Piston head, 16 ... Piston rod, 21 ... Permanent magnet, 22 ... Head unit, 23 ... Fixed member, 24 ... Port member, 25 ... Bottom member, 39 Reference surface, 42 ... head side oil chamber, 43 ... mounting portion, 51 ... magnetostrictive sensor, 52 ... sensor body, 54 ... magnetostrictive wire, 58 ... wave washer, 61 ... mounting portion, 80 ... spacer, 92 ... clevis.

Claims (9)

In the fluid cylinder provided with a sensor for detecting the position of the piston by detecting the magnet provided on the piston,
A head unit is provided at one end of the cylinder tube, a sensor main body is provided inside the head unit, and a magnetostrictive wire for sending an excitation pulse from the sensor main body is provided at a central position in the piston rod. The unit is provided with a mounting portion that opens on a cylinder tube side, the sensor main body is mounted in the mounting portion, and the sensor main body is seated on the bottom of the mounting portion.   2. The fluid cylinder according to claim 1, wherein the head unit includes a bottom member having the mounting portion and a port member that is located on a rod side of the bottom member and has a port through which a working fluid enters and exits.   The fluid cylinder according to claim 2, wherein the port is disposed between the sensor main body and a magnet in a state where the piston is at an immersive end in correspondence with a position.   The fluid cylinder according to claim 2, further comprising an urging unit that urges the sensor body in the seating direction.   The fluid cylinder according to claim 4, wherein the urging means is constituted by a wave washer interposed between the port member and the sensor body.   The head unit includes a fixing member fixed to the outer periphery of the cylinder tube and a bottom member having an attachment portion for attachment to an external device, and the port member is sandwiched between the fixing member and the bottom member. The fluid cylinder according to any one of claims 2 to 5.   The fluid cylinder according to claim 6, wherein the port member has a restricting surface for restricting a moving end of the immersive side of the piston.   The fluid cylinder according to claim 4, wherein a spacer having a regulating surface for regulating a moving end of the piston on the rod side of the bottom member is provided.   The fluid cylinder according to claim 8, wherein the biasing means is constituted by a wave washer interposed between the port member and the spacer.

Images