Fluid pressure cylinder

Abstract

This invention allows for easy attachment of magnetic sensors to cylinder tubes made of steel materials without dissimilar welding, while also improving the detection accuracy of the magnetic sensors. [Solution] The hydraulic cylinder 100 comprises a cylinder tube 10 made of steel material, a magnet 40 provided inside the cylinder tube 10 and reciprocating together with a piston rod 20, a magnetic sensor 50, and a first mounting portion 60 for attaching the magnetic sensor 50 to the outer circumferential surface of the cylinder tube 10. The first mounting portion 60 has a pair of bases 61 made of steel material and fixed to the outer circumferential surface of the cylinder tube 10 by welding, a main body portion 62 made of a non-magnetic material and fixed across the pair of bases 61 to press the magnetic sensor 50 against the outer circumferential surface of the cylinder tube 10, and a set screw 66 provided on the main body portion 62 to hold the magnetic sensor 50 and prevent it from rotating.

Description

Technical Field

[0006] , , ,

[0005] ,

[0001] The present invention relates to a hydraulic cylinder.

Background Art

[0002] Patent Document 1 discloses a hydraulic cylinder provided with a magnetic sensor that detects the magnetic flux density of a magnet attached to a piston. The magnetic sensor is disposed on the outer peripheral surface of the cylinder tube of the hydraulic cylinder and detects the stroke of the piston.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 does not specifically disclose a method for attaching a magnetic sensor to the outer peripheral surface of a cylinder tube. The attachment portion for attaching the magnetic sensor is formed of a non-magnetic material so as not to inhibit the detection of magnetism by the magnetic sensor. However, for example, when attaching the magnetic sensor to a cylinder tube generally formed of a steel material by welding, it becomes a dissimilar welding between the cylinder tube of the steel material (magnetic material) and the non-magnetic attachment portion. Therefore, attachment by welding becomes difficult. Further, in order to improve the detection accuracy of the magnetic sensor, it is required to attach the magnetic sensor so as not to move with respect to the cylinder tube.

[0005] The present invention has been made in view of the above problems, and an object thereof is to easily attach a magnetic sensor to a cylinder tube formed of a steel material without performing dissimilar welding and to improve the detection accuracy of the magnetic sensor.

Means for Solving the Problems

[0006] The present invention relates to a fluid pressure cylinder comprising: a cylinder tube made of steel material; a piston rod reciprocally provided within the cylinder tube; a piston connected to the piston rod and slidably housed within the cylinder tube; a magnet provided within the cylinder tube and reciprocating together with the piston rod; a magnetic sensor extending in the axial direction of the cylinder tube and attached to the outer circumferential surface of the cylinder tube, which detects the stroke of the piston rod and piston by the magnetic field of the magnet; and a first mounting portion for attaching the magnetic sensor to the outer circumferential surface of the cylinder tube. The first mounting portion comprises: a pair of bases made of steel material and fixed to the outer circumferential surface of the cylinder tube by welding; a main body made of a non-magnetic material, fixed across the pair of bases and pressing the magnetic sensor against the outer circumferential surface of the cylinder tube; and a rotation-stopping member provided on the main body for holding the magnetic sensor and preventing it from rotating.

[0007] In this invention, a pair of bases made of the same material as the cylinder tube (steel material) are fixed to the outer surface of the cylinder tube by welding, and a main body made of a non-magnetic material is fixed across the pair of bases. Therefore, by fixing the main body to the outer surface of the cylinder tube via the pair of bases, a magnetic sensor can be easily attached without dissimilar welding. Furthermore, the main body presses the magnetic sensor against the outer surface of the cylinder tube, preventing the magnetic sensor from moving in the axial and radial directions of the cylinder tube, and a rotation-preventing member holds the end of the magnetic sensor, thereby preventing the magnetic sensor from rotating. Therefore, the detection accuracy of the magnetic sensor can be improved.

[0008] The present invention is characterized in that the main body has a groove formed therein for housing at least a portion of the magnetic sensor.

[0009] In this invention, the groove in the main body allows for the positioning of the magnetic sensor relative to the cylinder tube.

[0010] The present invention is characterized in that a pair of rotation-preventing members are provided to clamp a magnetic sensor, and the main body is formed with a pair of first insertion holes through which fixing members for fixing the main body to a pair of bases are inserted, and a pair of second insertion holes through which the pair of rotation-preventing members are inserted, the pair of first insertion holes being elongated holes extending in the axial direction, and the pair of second insertion holes being formed in multiple locations arranged in the axial direction.

[0011] In this invention, the axial mounting position of the magnetic sensor can be adjusted after welding the pair of bases.

[0012] The present invention is characterized in that the main body comprises a first main body fixed across a pair of bases, and a second main body provided between the first main body and the magnetic sensor, which presses the magnetic sensor against the outer surface of the cylinder tube and is provided with a rotation-preventing member, and the first main body and the second main body are provided separately.

[0013] In this invention, the main body is divided into a first main body and a second main body, thus reducing the amount of scrap material discarded during the formation of the main body.

[0014] The present invention relates to a fluid pressure cylinder comprising a pair of bases made of steel material and fixed to the outer surface of a cylinder tube by welding, and a main body fixed across the pair of bases, further comprising a second mounting portion for attaching a magnetic sensor to the outer surface of the cylinder tube, wherein the magnetic sensor comprises a detection portion formed along the axial direction of the cylinder tube for detecting the stroke of a piston rod and a piston, and a tip portion of the detection portion to which a connector is provided, the tip portion being attached by the first mounting portion, the detection portion being attached by the second mounting portion, and the first main body portion of the first mounting portion and the main body portion of the second mounting portion being common members.

[0015] In this invention, the main body of the second mounting part can be made common with the first main body of the first mounting part, thus reducing the number of parts. [Effects of the Invention]

[0016] According to the present invention, a magnetic sensor can be easily attached to a cylinder tube made of a steel material without dissimilar welding, and the detection accuracy of the magnetic sensor can be improved.

Brief Description of the Drawings

[0017] [Figure 1] It is a partial cross-sectional view of a fluid pressure cylinder according to an embodiment of the present invention. [Figure 2] It is an external view of a fluid pressure cylinder according to an embodiment of the present invention. [Figure 3] It is a view of the fluid pressure cylinder seen from the direction of arrow III shown in FIG. 2. [Figure 4] It is a perspective view of the first attachment portion. [Figure 5] It is a perspective view of the second attachment portion. [Figure 6] It is a perspective view of the main body portion of the first attachment portion according to Modification 1 of the embodiment of the present invention. [Figure 7] It is a perspective view of the main body portion of the first attachment portion according to Modification 1 of the embodiment of the present invention. [Figure 8] It is a perspective view of the main body portion of the first attachment portion according to Modification 2 of the embodiment of the present invention. [Figure 9] It is a perspective view of the main body portion of the first attachment portion according to Modification 3 of the embodiment of the present invention.

Modes for Carrying Out the Invention

[0018] Referring to the drawings, a fluid pressure cylinder according to an embodiment of the present invention will be described. Hereinafter, a hydraulic cylinder 100 using hydraulic oil as the working fluid will be described.

[0019] First, referring to FIGS. 1 and FIGS. 2, the overall configuration of the hydraulic cylinder

[0020] As shown in Figure 1, the hydraulic cylinder 100 includes a cylinder tube 10, a piston rod 20 reciprocally mounted within the cylinder tube 10, a piston 30 connected to the piston rod 20 and slidably housed within the cylinder tube 10, a cylinder head 12 that closes the opening at one end of the cylinder tube 10 through which the piston rod 20 is inserted, a cylinder bottom 13 that closes the opening at the other end of the cylinder tube 10, and a magnet 40 mounted within the cylinder tube 10 that reciprocates together with the piston rod 20. The magnet 40 is used to detect the stroke of the piston rod 20 and the piston 30 by a magnetic sensor 50, which will be described later.

[0021] The cylinder tube 10 is formed of a magnetic material made of steel. The cylinder head 12 is fastened to the cylinder tube 10 via, for example, a plurality of fastening members such as bolts (not shown). The cylinder bottom 13 is joined to the cylinder tube 10 by welding, for example. The rod side chamber 2 is partitioned by the cylinder tube 10, the cylinder head 12, and the piston 30, and the non-rod side chamber 3 is partitioned by the cylinder tube 10, the cylinder bottom 13, and the piston 30. A head-side port 11a is formed on the cylinder head 12 side of the cylinder tube 10 as a supply and discharge port that communicates with the rod side chamber 2. Hereafter, the axial direction of the cylinder tube 10 will be simply referred to as the "axial direction," the radial direction of the cylinder tube 10 as the "radial direction," and the circumferential direction of the cylinder tube 10 as the "circumferential direction."

[0022] The cylinder head 12 is formed in an annular shape and slidably supports the piston rod 20. The cylinder bottom 13 has a bottom-side port 13a and a passage 13b which serve as supply and discharge ports communicating with the anti-rod side chamber 3.

[0023] The piston rod 20 includes a rod body 21 slidably supported by the cylinder head 12, a piston fixing portion 22 on which the piston 30 is provided and fixed, and a tip portion 23 formed to be smaller in diameter than the piston fixing portion 22. In the piston rod 20, the rod body 21, the piston fixing portion 22, and the tip portion 23 are arranged in this order in the axial direction. Steps are formed between adjacent rod bodies 21, piston fixing portions 22, and tip portions 23. In the piston rod 20, the rod body 21 has the largest diameter, and the tip portion 23 has the smallest diameter. A male thread (not shown) is formed on the outer circumferential surface of the end of the piston fixing portion 22 on the tip portion 23 side.

[0024] A holder 41 for holding the magnet 40 is attached to the outer circumferential surface of the tip portion 23. This attaches the magnet 40 to the piston rod 20 (tip portion 23) via the holder 41. The magnet 40 is a permanent magnet such as neodymium, and is provided on a part of the circumferential direction of the cylinder tube 10 so as to face the magnetic sensor 50 (see Figures 2-5) on either side of the cylinder tube 10. Specifically, the magnet 40 is provided in an area smaller than half the circumference of the cylinder tube 10. When the holder 41 is attached to the tip portion 23, the holder 41 and the magnet 40 are provided so as not to contact (be attracted to) the inner circumferential surface of the cylinder tube 10. Therefore, even if the magnet 40 is provided inside the cylinder tube 10 which is made of a magnetic material, the operation of the hydraulic cylinder 100 is not hindered. Even if the magnet 40 were to be attracted to the inner circumferential surface of the cylinder tube 10 by magnetic force, the stroke direction of the piston rod 20 and piston 30 is perpendicular to the lines of force of the magnetic force, so it would have almost no effect on the stroke of the piston rod 20 and piston 30. Therefore, it is preferable that the magnet 40 does not adhere to the inner circumferential surface of the cylinder tube 10, but it is also possible that the magnet 40 is adhered to the inner circumferential surface of the cylinder tube 10.

[0025] The piston 30 is formed in an annular shape. A nut portion 35 is formed on one axial end of the piston 30 (right side in Figure 1), and a female thread (not shown) is formed on the inner circumferential surface of the nut portion 35. The piston 30 is connected to the piston rod 20 by screwing the female thread of the nut portion 35 of the piston 30 with the male thread of the piston fixing portion 22 of the piston rod 20. A sealing member 31 is provided on the outer circumferential surface of the piston 30. This blocks communication between the rod-side chamber 2 and the non-rod-side chamber 3 through the space between the inner circumferential surface of the cylinder tube 10 and the outer circumferential surface of the piston 30.

[0026] In such a hydraulic cylinder 100, when hydraulic fluid is supplied from a hydraulic source (working fluid pressure source) to the anti-rod side chamber 3 through the bottom side port 13a and passage 13b, the piston rod 20 and piston 30 move in a direction that reduces the rod side chamber 2, and the hydraulic cylinder 100 extends. At this time, the hydraulic fluid in the rod side chamber 2 is discharged to a tank (not shown) through the head side port 11a.

[0027] Furthermore, when hydraulic fluid is supplied from the hydraulic source to the rod-side chamber 2 through the head-side port 11a, the piston rod 20 and piston 30 move in a direction that reduces the anti-rod-side chamber 3, causing the hydraulic cylinder 100 to contract. At this time, the hydraulic fluid in the anti-rod-side chamber 3 is discharged to the tank through the bottom-side port 13a and passage 13b.

[0028] Next, we will explain the configuration of the magnetic sensor 50 in detail.

[0029] Figure 3 is a view of the dotted area shown in Figure 2 from the direction of arrow III. Figure 4 is a perspective view showing the magnetic sensor 50 attached by the first mounting part 60, and Figure 5 is a perspective view showing the magnetic sensor 50 attached by the second mounting part 70.

[0030] As shown in Figures 2 to 5, the hydraulic cylinder 100 includes a magnetic sensor 50 that extends axially along the cylinder tube 10 and is attached to the outer surface of the cylinder tube 10, and detects the stroke of the piston rod 20 and piston 30 by the magnetic field of a magnet 40, and a first mounting portion 60 and a second mounting portion 70 for attaching the magnetic sensor 50 to the outer surface of the cylinder tube 10. In this embodiment, one first mounting portion 60 is provided, and multiple second mounting portions 70 are provided (see Figure 2).

[0031] The magnetic sensor 50 has a detection unit 51 formed along the axial direction to detect the stroke of the piston rod 20 and the piston 30, and a tip unit 52 on which a connector 53 is provided. The tip unit 52 is the tip of the detection unit 51, and an annular groove 52a is formed in the tip unit 52. The connector 53 has a circular cross-section.

[0032] The detection unit 51 includes a cylindrical protective unit 51a extending in the axial direction, a Hall element (not shown) provided within the protective unit 51a, and an electronic circuit board (not shown) on which the Hall element is mounted. Multiple Hall elements are provided at intervals in the axial direction. One or more electronic circuit boards are provided extending axially across the entire protective unit 51a. The protective unit 51a and the Hall element are provided to a length that allows the entire stroke (both ends of the stroke) of the piston rod 20 and piston 30 to be detected. The connector 53 is connected to a processing unit (not shown) that processes the detection results of the Hall element. The magnetic sensor 50 outputs the detection result, obtained by detecting the magnetism of the magnet 40 using the Hall element, to the processing unit via the connector 53, thereby detecting the stroke of the piston rod 20 and piston 30 (for example, displacement from the initial position). The tip 52 of the magnetic sensor 50 is attached and fixed by the first mounting part 60 (see Figures 2, 3, and 4), and the detection part 51 (protection part 51a) is attached and fixed by the second mounting part 70 (see Figures 2, 3, and 5).

[0033] As shown in Figures 3 and 4, the first mounting portion 60 includes a pair of bases 61 (see Figure 4) made of steel material and fixed to the outer circumferential surface of the cylinder tube 10 by welding, a main body portion 62 made of a non-magnetic material and fixed across the pair of bases 61 to press the magnetic sensor 50 against the outer circumferential surface of the cylinder tube 10, and a pair of set screws 66 (see Figure 4) provided on the main body portion 62 as rotation-preventing members that clamp the magnetic sensor 50 to prevent rotation.

[0034] As shown in Figure 4, the pair of bases 61 are each formed in a block shape and are provided parallel to each other with a gap between them in the circumferential direction of the cylinder tube 10. Since the pair of bases 61 are made of steel material, that is, the same material as the cylinder tube 10, they can be fixed to the outer surface of the cylinder tube 10 by welding. The pair of bases 61 are made of a magnetic material and do not generate magnetic force on their own, but generate magnetic force when they receive the magnetic force of the permanent magnet magnet 40, thus affecting the detection accuracy of the magnetic sensor 50. However, since the pair of bases 61 are provided at a distance from the magnetic sensor 50, the impact on the detection accuracy of the magnetic sensor 50 can be reduced. Fastening holes (not shown) are formed on the upper surface 61a of the pair of bases 61, into which bolts 65, which serve as fixing members, are fastened.

[0035] The main body portion 62 is formed in a plate shape. Since the main body portion 62 is for fixing the magnetic sensor 50 (in other words, adjacent to the magnetic sensor 50), it is made of a non-magnetic material such as stainless steel so as not to interfere with the detection of magnetism by the magnetic sensor 50. The main body portion 62 has a fixing portion 62a that is provided and fixed across a pair of bases 61, and a protruding portion 62b that is formed projecting axially from the fixing portion 62a. The fixing portion 62a has a pair of first insertion holes 62d through which bolts 65 for fixing the main body portion 62 to the pair of bases 61 are inserted, and a groove 62c that accommodates a part of the detection portion 51 (protection portion 51a) of the magnetic sensor 50. The groove 62c is formed along the axial direction, and the positioning of the magnetic sensor 50 relative to the cylinder tube 10 (circumferential positioning) is achieved by accommodating a part of the detection portion 51 in the groove 62c. With a portion of the detection unit 51 housed in the groove 62c, the bolt 65 is inserted through the pair of first insertion holes 62d and fastened to the fastening holes of the pair of bases 61, thereby fixing the main body 62 to the pair of bases 61 while pressing its tip 52 against the outer circumferential surface of the cylinder tube 10. This prevents the magnetic sensor 50 from moving in the axial and radial directions of the cylinder tube 10. When the main body 62 is fixed to the pair of bases 61, a gap is formed between the main body 62 and the pair of bases 61 so that the main body 62 can press its tip 52 against the outer circumferential surface of the cylinder tube 10. Since the main body 62 and the pair of bases 61 do not come into contact, the axial force due to the tightening of the bolt 65 is reduced, but the bolt 65 is prevented from loosening by providing a spring washer 68 on the seating surface of the bolt 65. Note that the spring washer 68 is not essential and may not be provided.

[0036] A pair of protrusions 62b are provided on the cylinder tube 10 so as to sandwich the tip 52 of the magnetic sensor 50 from both sides in the circumferential direction. A pair of second insertion holes 62e are formed in the protrusions 62b, through which a pair of set screws 66 are inserted. The pair of set screws 66 are inserted through the pair of second insertion holes 62e, and the pair of set screws 66 are housed in the annular groove 52a of the tip 52 of the magnetic sensor 50, thereby clamping (holding) the tip 52, which prevents rotation of the magnetic sensor 50 while preventing axial movement.

[0037] Thus, in the first mounting portion 60, the main body portion 62, which is made of a non-magnetic material, has the function of fixing the magnetic sensor 50, and the pair of bases 61, which are made of steel material (magnetic material), have the function of assisting in fixing the main body portion 62 to the outer surface of the cylinder tube 10. In this embodiment, the pair of bases 61, which are made of the same material as the cylinder tube 10 (steel material and magnetic material), are fixed to the outer surface of the cylinder tube 10 by welding, and the main body portion 62, which is made of a non-magnetic material, is fixed across the pair of bases 61. Therefore, even if the material of the cylinder tube 10 to be mounted and the material of the main body portion 62 that fixes the magnetic sensor 50 are different, the magnetic sensor 50 can be easily attached without dissimilar welding by fixing the main body portion 62 to the outer surface of the cylinder tube 10 via the pair of bases 61. Furthermore, the main body 62 presses the magnetic sensor 50 against the outer circumferential surface of the cylinder tube 10, preventing the magnetic sensor 50 from moving in the axial and radial directions of the cylinder tube 10. The pair of set screws 66 clamp the end of the magnetic sensor 50, preventing it from rotating. Thus, the detection accuracy of the magnetic sensor 50 can be improved.

[0038] As shown in Figures 3 and 5, the second mounting portion 70 includes a pair of bases 71 (see Figure 5) made of steel material and fixed to the outer surface of the cylinder tube 10 by welding, and a main body portion 72 made of a non-magnetic material, fixed across the pair of bases 71, and pressing the magnetic sensor 50 against the outer surface of the cylinder tube 10.

[0039] As shown in Figure 5, the pair of bases 71 have the same configuration as the pair of bases 61 of the first mounting portion 60, and fastening holes (not shown) into which bolts 65 are fastened are formed on the upper surface 71a of each.

[0040] The main body portion 72 is formed in a plate shape. Since the main body portion 72, like the main body portion 62 of the first mounting portion 60, is used to fix the magnetic sensor 50, it is formed of a non-magnetic material such as stainless steel so as not to interfere with the detection of magnetism by the magnetic sensor 50.

[0041] The main body portion 72 has the same configuration as the fixing portion 62a of the main body portion 62 of the first mounting portion 60 (in other words, the main body portion 62 does not have a protruding portion 62b). Specifically, the main body portion 72 has a pair of through holes 72d through which bolts 65 for fixing the main body portion 72 to a pair of bases 71 are inserted, and a groove 72c that accommodates a part of the detection portion 51 (protection portion 51a) of the magnetic sensor 50. By accommodating a part of the detection portion 51 in the groove 72c formed along the axial direction, the magnetic sensor 50 is positioned relative to the cylinder tube 10 (circumferential positioning). With a part of the detection portion 51 accommodated in the groove 72c, the bolts 65 are inserted through the pair of through holes 72d and fastened to the fastening holes of the pair of bases 71, thereby fixing the main body portion 72 to the pair of bases 71 while pressing the detection portion 51 against the outer circumferential surface of the cylinder tube 10. This prevents the magnetic sensor 50 from moving in the axial and radial directions of the cylinder tube 10. When the main body 72 is fixed to the pair of bases 71, a gap is formed between the main body 72 and the pair of bases 71 so that the main body 72 can press the detection unit 51 against the outer surface of the cylinder tube 10. Since the main body 72 and the pair of bases 71 do not come into contact, the axial force due to tightening the bolt 65 is reduced, but the bolt 65 is prevented from loosening by providing a spring washer 68 on the seating surface of the bolt 65. Note that the spring washer 68 is not essential and may not be provided.

[0042] Thus, in the second mounting section 70, similar to the first mounting section 60, the main body 72, which is made of a non-magnetic material, has the function of fixing the magnetic sensor 50, and the pair of bases 71, which are made of steel material (magnetic material), have the function of assisting in fixing the main body 72 to the outer surface of the cylinder tube 10. Therefore, by fixing the main body 72 to the outer surface of the cylinder tube 10 via the pair of bases 71, the magnetic sensor 50 can be easily attached without dissimilar welding. Furthermore, by pressing the detection part 51 of the magnetic sensor 50 against the outer surface of the cylinder tube 10 at multiple points using the second mounting section 70, the detection part 51 can be prevented from moving in the axial and radial directions of the cylinder tube 10 more than when only the first mounting section 60 is provided, thereby improving the detection accuracy of the magnetic sensor 50.

[0043] According to the above embodiment, the following effects and advantages are achieved.

[0044] At the first mounting section 60 and the second mounting section 70, the main body sections 62 and 72 are fixed to the outer surface of the cylinder tube 10 via a pair of bases 61 and 71, allowing for easy attachment of the magnetic sensor 50 without dissimilar welding. Furthermore, the main body sections 62 and 72 press the magnetic sensor 50 against the outer surface of the cylinder tube 10, preventing the magnetic sensor 50 from moving in the axial and radial directions of the cylinder tube 10. The pair of set screws 66 clamp the ends of the magnetic sensor 50, preventing it from rotating. Thus, the detection accuracy of the magnetic sensor 50 can be improved.

[0045] Next, modifications of this embodiment will be described. The following modifications are also within the scope of the present invention, and it is possible to combine the configurations shown in the modifications with the configurations described in the above embodiments, or to combine the configurations described in the following different modifications.

[0046] <Example 1> In the above embodiment, the main body 62 of the first mounting portion 60 has a fixing portion 62a that is provided and fixed across a pair of bases 61, and a pair of protruding portions 62b that are formed to project axially from the fixing portion 62a. However, the configuration of the main body 62 is not limited to the above, as long as it is made of a non-magnetic material and can be fixed across a pair of bases 61 to press the magnetic sensor 50 against the outer circumferential surface of the cylinder tube 10. For example, as shown in Figure 6, the main body 162 may have a configuration that includes a plate-shaped fixing portion 162a that is provided and fixed across a pair of bases 61, and a notch 162b formed in the fixing portion 162a into which the tip portion 52 of the magnetic sensor 50 fits. Similar to the above embodiment, a first insertion hole 62d and a groove 62c are formed in the fixing portion 162a. A pair of second insertion holes 62e, through which a pair of set screws 66 are inserted, are formed to communicate the outer circumferential surface of the fixing portion 162a and the notch 162b. The tip 52 of the magnetic sensor 50 fits into the notch 162b, and the pair of set screws 66 are inserted into the pair of second insertion holes 62e, respectively, and the tip 52 of the magnetic sensor 50 is clamped, thereby preventing the magnetic sensor 50 from rotating.

[0047] Furthermore, as shown in Figure 7, the main body portion 262 may have a configuration in which circular insertion portions 262f are formed at both ends of the fixing portion 62a, each with a first insertion hole 62d, and circular insertion portions 262g are formed at the tips of the pair of protruding portions 62b, each with a second insertion hole 62e. These configurations also provide the same effects as the embodiments described above.

[0048] <Modification 2> In the above embodiment, the main body 62 of the first mounting portion 60 has a fixing portion 62a that is provided and fixed across a pair of bases 61, and a pair of protruding portions 62b that are formed projecting axially from the fixing portion 62a. The fixing portion 62a has a pair of first insertion holes 62d through which bolts 65 are inserted, and the protruding portions 62b have a pair of second insertion holes 62e through which a pair of set screws 66 are inserted. Here, as shown in Figure 8, the pair of first insertion holes 62d may be elongated holes extending in the axial direction, and the pair of second insertion holes 62e may be formed in multiple locations arranged in the axial direction. In this configuration, the mounting position of the magnetic sensor 50 can be adjusted in the axial direction after welding the pair of bases 61.

[0049] <Variation 3> In the above embodiment, the main body portion 62 of the first mounting portion 60 is formed from a single member. However, the main body portion 62 may be formed from two members. Specifically, as shown in Figure 9, the main body portion 362 has a first main body portion 362a fixed across a pair of bases 61, and a second main body portion 362b provided between the first main body portion 362a and the magnetic sensor 50, which presses the magnetic sensor 50 against the outer circumferential surface of the cylinder tube 10 and is provided with a pair of set screws 66. The first main body portion 362a and the second main body portion 362b may be provided as separate bodies. The first main body portion 362a has the same configuration as the fixing portion 62a of the main body portion 62 in the above embodiment (in other words, the main body portion 62 does not have a protruding portion 62b), and a first insertion hole 62d is formed therein. The second main body portion 362b has a receiving recess 362h in which the first main body portion 362a is accommodated, and a pair of protrusions 362i that are formed to protrude axially, similar to the pair of protrusions 62b, and a second insertion hole 62e is formed in each of the pair of protrusions 362i. In this configuration, since the main body portion 362 is divided into the first main body portion 362a and the second main body portion 362b, the amount of scrap material discarded when forming the main body portion 362 by press molding can be reduced. Alternatively, a groove 62c may be formed in the first main body portion 362a, and the first main body portion 362a of the first mounting portion 60 and the main body portion 72 of the second mounting portion 70 may be made common members. In this configuration, since the main body portion 72 of the second mounting portion 70 can be made common with the first main body portion 362a of the first mounting portion 60, the number of parts can be reduced.

[0050] <Modification 4> In the above embodiment, a groove 62c is formed in the fixing portion 62a of the first mounting portion 60, which accommodates a part of the detection portion 51 of the magnetic sensor 50. By accommodating a part of the detection portion 51 in the groove 62c, the magnetic sensor 50 is positioned (circumferentially positioned) relative to the cylinder tube 10. The groove 62c may accommodate the entire magnetic sensor 50. Furthermore, the groove 62c is not necessarily an essential component, and it is not required that a groove 62c be formed in the fixing portion 62a.

[0051] <Modification 5> In the above embodiment, the hydraulic cylinder 100 is equipped with a first mounting portion 60 and a second mounting portion 70, the tip portion 52 of the magnetic sensor 50 is attached by the first mounting portion 60, and the detection portion 51 is attached by the second mounting portion 70. However, the second mounting portion 70 is not necessarily an essential component, and the hydraulic cylinder 100 may be equipped with only the first mounting portion 60. Even with this configuration, the magnetic sensor 50 can be easily attached without dissimilar welding, and the detection accuracy of the magnetic sensor 50 can be improved by fixing the tip portion 52 of the magnetic sensor 50 with the first mounting portion 60.

[0052] <Variation 6> In the above embodiment, the first mounting portion 60 has a pair of set screws 66 that clamp the magnetic sensor 50 and prevent it from rotating. However, it is not limited to this configuration, and there may be only one set screw 66 that holds the tip portion 52 of the magnetic sensor 50 from one side.

[0053] The configuration, operation, and effects of the embodiment of the present invention configured as described above will be summarized below.

[0054] The hydraulic cylinder 100, as a fluid pressure cylinder, comprises a cylinder tube 10 made of steel, a piston rod 20 reciprocatingly mounted within the cylinder tube 10, a piston 30 connected to the piston rod 20 and slidably housed within the cylinder tube 10, a magnet 40 mounted within the cylinder tube 10 and reciprocating together with the piston rod 20, and a magnetic sensor extending axially from the cylinder tube 10 and attached to the outer surface of the cylinder tube 10, which detects the stroke of the piston rod 20 and the piston 30 by the magnetic field of the magnet 40. The device comprises a sensor 50 and a first mounting portion 60 for attaching the magnetic sensor 50 to the outer circumferential surface of the cylinder tube 10. The first mounting portion 60 includes a pair of bases 61 made of steel and fixed to the outer circumferential surface of the cylinder tube 10 by welding, a main body portion 62, 162, 262, 362 made of a non-magnetic material and fixed across the pair of bases 61 to press the magnetic sensor 50 against the outer circumferential surface of the cylinder tube 10, and a set screw 66 provided on the main body portion 62, 162, 262, 362 as a rotation-preventing member that holds the magnetic sensor 50 and prevents it from rotating.

[0055] In this configuration, a pair of bases 61, made of the same material as the cylinder tube 10 (steel material), are fixed to the outer surface of the cylinder tube 10 by welding, and the main body portions 62, 162, 262, and 362, made of a non-magnetic material, are fixed across the pair of bases 61. Therefore, by fixing the main body portions 62, 162, 262, and 362 to the outer surface of the cylinder tube 10 via the pair of bases 61, the magnetic sensor 50 can be easily attached without welding dissimilar materials. Furthermore, the main body portions 62, 162, 262, and 362 press the magnetic sensor 50 against the outer surface of the cylinder tube 10, preventing the magnetic sensor 50 from moving in the axial and radial directions of the cylinder tube 10, and the set screw 66 holds the end of the magnetic sensor 50, preventing it from rotating. Therefore, the detection accuracy of the magnetic sensor 50 can be improved.

[0056] Furthermore, in the hydraulic cylinder 100, grooves 62c are formed in the main body portions 62, 162, 262, and 362, which accommodate at least a portion of the magnetic sensor 50.

[0057] In this configuration, the grooves 62c of the main body sections 62, 162, 262, and 362 allow for the positioning of the magnetic sensor 50 relative to the cylinder tube 10.

[0058] Furthermore, in the hydraulic cylinder 100, a pair of set screws 66 are provided to clamp the magnetic sensor 50, and the main body 62 is formed with a pair of first insertion holes 62d through which bolts 65, which serve as fixing members for fixing the main body 62 to a pair of bases 61, are inserted, and a pair of second insertion holes 62e through which a pair of set screws 66 are inserted. The pair of first insertion holes 62d are elongated holes extending in the axial direction, and the pair of second insertion holes 62e are formed in multiple locations arranged in the axial direction.

[0059] In this configuration, the mounting position of the magnetic sensor 50 can be adjusted axially after welding the pair of bases 61.

[0060] Furthermore, in the hydraulic cylinder 100, the main body 362 has a first main body 362a fixed across a pair of bases 61, and a second main body 362b provided between the first main body 362a and the magnetic sensor 50, which presses the magnetic sensor 50 against the outer circumferential surface of the cylinder tube 10 and is provided with a set screw 66. The first main body 362a and the second main body 362b are provided as separate bodies.

[0061] In this configuration, the main body 362 is divided into a first main body 362a and a second main body 362b, which reduces the amount of scrap material discarded when forming the main body 362.

[0062] Furthermore, the hydraulic cylinder 100 has a pair of bases 71 made of steel material and fixed to the outer surface of the cylinder tube 10 by welding, and a main body portion 72 fixed across the pair of bases 71, and further includes a second mounting portion 70 for attaching a magnetic sensor 50 to the outer surface of the cylinder tube 10, and the magnetic sensor 50 has a detection portion 51 formed along the axial direction of the cylinder tube 10 and for detecting the stroke of the piston rod 20 and piston 30, and a tip portion 52 which is the tip of the detection portion 51 and is provided with a connector 53, the tip portion 52 is attached by a first mounting portion 60 and the detection portion 51 is attached by a second mounting portion 70, and the first main body portion 362a of the first mounting portion 60 and the main body portion 72 of the second mounting portion 70 are common members.

[0063] In this configuration, the main body portion 72 of the second mounting portion 70 can be shared with the first main body portion 362a of the first mounting portion 60, thus reducing the number of parts.

[0064] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. [Explanation of symbols]

[0065] 10...Cylinder tube, 20...Piston rod, 30...Piston, 40...Magnet, 50...Magnetic sensor, 51...Detection unit, 52...Tip, 53...Connector, 60...First mounting part, 61...Base, 62, 162, 262, 362...Main body, 62c...Groove, 62d...First insertion hole, 62e...Second insertion hole, 65...Bolt (fixing member), 66...Set screw (rotation stopper member), 70...Second mounting part, 71...Base, 72...Main body, 100...Hydraulic cylinder (fluid pressure cylinder), 362a...First main body, 362b...Second main body

Claims

1. A cylinder tube made of steel material, A piston rod is provided within the cylinder tube so as to be reciprocable, A piston connected to the piston rod and slidably housed within the cylinder tube, A magnet provided inside the cylinder tube and reciprocating together with the piston rod, A magnetic sensor extends axially along the cylinder tube and is attached to the outer surface of the cylinder tube, and detects the stroke of the piston rod and the piston by the magnetic field of the magnet, The system includes a first mounting portion for attaching the magnetic sensor to the outer surface of the cylinder tube, The first mounting portion is, A pair of bases formed from steel material and fixed to the outer surface of the cylinder tube by welding, A main body made of a non-magnetic material, fixed across the pair of bases, and pressing the magnetic sensor against the outer surface of the cylinder tube, A fluid pressure cylinder characterized by having a rotation-stopping member provided on the main body portion, which holds the magnetic sensor and prevents rotation.

2. A fluid pressure cylinder according to claim 1, A fluid pressure cylinder characterized in that a groove is formed in the main body portion for housing at least a part of the magnetic sensor.

3. A fluid pressure cylinder according to claim 1, The aforementioned rotation-preventing members are provided in pairs to clamp the magnetic sensor, The main body is formed with a pair of first insertion holes through which fixing members for securing the main body to the pair of bases are inserted, and a pair of second insertion holes through which the pair of rotation-preventing members are inserted. A fluid pressure cylinder characterized in that the pair of first insertion holes are elongated holes extending in the axial direction, and the pair of second insertion holes are formed in multiple locations in the axial direction.

4. A fluid pressure cylinder according to any one of claims 1 to 3, The main body is, A first main body fixed across the pair of bases, The system includes a second main body provided between the first main body and the magnetic sensor, which presses the magnetic sensor against the outer circumferential surface of the cylinder tube and is provided with the rotation-preventing member, A fluid pressure cylinder characterized in that the first main body and the second main body are each provided separately.

5. A fluid pressure cylinder according to claim 4, It comprises a pair of bases made of steel material and fixed to the outer surface of the cylinder tube by welding, and a main body fixed across the pair of bases, and further comprises a second mounting portion for attaching the magnetic sensor to the outer surface of the cylinder tube, The magnetic sensor comprises a detection unit formed along the axial direction of the cylinder tube for detecting the stroke of the piston rod and the piston, and a tip portion of the detection unit to which a connector is provided. The tip portion is attached by the first mounting portion, The detection unit is attached by the second mounting unit, A fluid pressure cylinder characterized in that the first main body portion of the first mounting portion and the main body portion of the second mounting portion are common members.

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