JP2013234693A - Hydraulic cylinder and hydraulic cylinder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic cylinder and a hydraulic cylinder device capable of efficiently securing the effective stroke of the hydraulic cylinder.SOLUTION: A hydraulic cylinder 1 is configured by sealing the opening end of a cylinder tube 2 made of a nonmagnetic body with cover members 3 and 4. The cover members 3 and 4 having tapered surfaces formed on an outer peripheral surface thereof are fitted in the inner peripheral surface of the opening end of the cylinder tube 2 having a tapered surface formed from the opening end surface to bring both tapered surfaces into tight contact with each other. The outer peripheral surfaces of both of the cover members 3 and 4 and the opening ends are covered with a joint member 10, and a helical groove formed in the inner peripheral surface of the joint member 10 is screwed to a helical groove formed in the outer peripheral surface of the opening end of the cylinder tube 2, thereby fixing the cover members 3 and 4 to the opening end of the cylinder tube 2.

Description

  The present invention relates to a hydraulic cylinder and a hydraulic cylinder device capable of efficiently ensuring an effective stroke of the hydraulic cylinder and detecting the position of a rod.

  In a hydraulic cylinder, as a typical structure for sealing the opening end of a cylinder tube, a cylinder member head side cover member and a rod side cover member are fastened and fixed with tie bolts (outside of JIS B 8367). ) In conformity with a hydraulic cylinder (hereinafter referred to as JIS standard hydraulic cylinder) and a hydraulic cylinder (hereinafter referred to as a welded hydraulic cylinder) having a structure in which a head side cover member and a rod side cover member are welded to a cylinder tube. Exists.

  The hydraulic cylinder has been conventionally provided as an actuator for a mechanism operating unit of an industrial machine or the like, and various proposals have been made to improve usability. The present inventor also provides a hydraulic cylinder device in which a hydraulic unit is integrally coupled to a JIS standard hydraulic cylinder (Patent Document 1). In order to control the hydraulic cylinder as an actuator according to the application, it is necessary to efficiently ensure an effective stroke and to accurately detect the position of the rod that expands and contracts from the cylinder tube.

  Therefore, the inventor of the present invention is a slide fixed to the outer peripheral surface of the cylinder tube from the head side end portion to the rod side end portion in order to detect the position of the rod that moves in a hydraulic cylinder with a simple structure and versatility. Rail, one or more proximity sensors arranged in the vicinity of both ends of the slide rail, a sensor detector slidably mounted on the slide rail, and a rod-side mounting portion of the rod that expands and contracts from the cylinder tube And a position detector comprising a connecting rod for connecting the sensor detectors (Patent Document 2).

  In addition, a detection tube fixed to the outer peripheral surface of the cylinder tube in the longitudinal direction and a proximity sensor attached to the outer peripheral surface of the detection tube are provided. The rod extends and contracts from the detection tube, and the tip of the rod extends and contracts from the cylinder tube. There is also provided a position detection device comprising a detection rod connected to the rod side mounting portion, a detection piston attached to the base end of the detection rod in the detection tube, and a sensor detection body attached to the detection piston (Patent Literature). 3).

Japanese Patent No. 3812929 Utility Model Registration No. 3149287 Utility Model Registration No. 3171858

  JIS standard hydraulic cylinders use tie bolts to connect the cylinder tube and the cover member, so a structure is required to equip the tie bolts. The distance between the fulcrums of a member becomes long. For this reason, the need to ensure the buckling strength is disadvantageous compared to the welding hydraulic cylinder in terms of efficiently ensuring the effective stroke of the cylinder with respect to the working pressure and the length of the cylinder tube. In contrast, welded hydraulic cylinders do not require tie bolts and their parts for connecting the cylinder tube and cover member, and the structure is simple, so even with the same extension stroke, compared to JIS standard hydraulic cylinders. Thus, the length of the distance between the fulcrum points of the head side member and the rod side member can be shortened. Therefore, it is advantageous over the JIS standard hydraulic cylinder in terms of ensuring buckling strength, and it is possible to efficiently ensure the effective stroke of the cylinder. That is, the welding hydraulic cylinder has the same inner diameter and rod diameter of the cylinder tube as compared with the JIS standard hydraulic cylinder, and can significantly improve the effective stroke of the cylinder when the output is the same.

  A welding hydraulic cylinder has a structure in which a cylinder tube and a cover member are connected by welding, and welding between dissimilar metals has problems in terms of strength, quality, reliability, etc. of the welded portion, and therefore, a cylinder tube as a cover member. It is required to use the same material. Since it is necessary to use a non-magnetic stainless steel tube as the cylinder tube, stainless steel is inevitably used as the cover member. Therefore, stainless steel is used up to the cover member which does not necessarily need to be a non-magnetic material, which increases the cost. On the other hand, since the JIS standard hydraulic cylinder does not require welding, low-cost iron can be used as a material for the cover member that does not need to be a non-magnetic material. And

  Since JIS standard hydraulic cylinders can use low-cost iron for the cover member, the cost can be reduced compared to welded hydraulic cylinders, but the effective stroke of the cylinder is efficient due to buckling restrictions. It is difficult to secure it. On the other hand, compared with JIS standard hydraulic cylinders, the welded hydraulic cylinder can efficiently secure the effective stroke of the cylinder, but since the cover member is welded to the cylinder tube, it is the same as the cylinder tube. It was necessary to use a material, and it was difficult to realize cost reduction. Therefore, both have merits and demerits, and a hydraulic cylinder that satisfies both merits is not provided.

  On the other hand, regarding the detection of the position of the rod, in the position detection device shown in Patent Document 2, since the sensor detection body that is exposed on the slide rail is slidably mounted, the sensor detection body is exposed to the outside. It is exposed as it is. Further, a clearance consisting of a narrow space is also required between the proximity sensor arranged on the slide rail and the sensor detection body. For this reason, as time passes, the exposed part is easily affected by dust, etc., and dust etc. may adhere or get caught in the space, resulting in insufficient clearance, in which case it may cause failure or malfunction There is a fear. Moreover, since the sensor detection body is exposed to the outside, it may interfere with other installation objects depending on the environment of the installation location. Furthermore, there is a risk that the wear of the sliding portion may cause a decrease in accuracy, malfunction, or a decrease in product life.

In addition, since the position detection device shown in Patent Document 3 uses a detection tube, the problem that the sensor detection body shown in Patent Document 2 is exposed to the outside can be solved.
A detection tube, detection rod, and detection piston that are separate from the hydraulic cylinder are required, and the detection rod needs to be linked with the expansion and contraction of the rod of the hydraulic cylinder, which increases the number of parts and complicates the structure. End up.

  Therefore, the present invention provides a hydraulic cylinder and a hydraulic cylinder device having a low-cost and simple structure capable of efficiently ensuring the effective stroke of the hydraulic cylinder and detecting the position of the rod. Objective.

  In order to achieve the above object, the present invention is a hydraulic cylinder in which an opening end portion of a cylinder tube made of a non-magnetic material is sealed with a cover member made of a magnetic material, and a cylinder having a tapered surface formed from the opening end surface A cover member with a tapered surface formed on the outer peripheral surface is fitted into the inner peripheral surface of the open end of the tube to bring both tapered surfaces into close contact, and the outer peripheral surface of both the cover member and the open end is covered with a joint member. Then, the screw groove engraved on the inner peripheral surface of the joint member is screwed with the screw groove engraved on the outer peripheral surface of the opening end of the cylinder tube, thereby fixing the cover member to the opening end of the cylinder tube. Provided on a cylinder basis.

  Then, the cylinder tube and the cover member are prevented from rotating by the close contact between both the tapered surfaces, and the axial centers of the cylinder tube and the cover member are made coincident with each other by the close contact between both the tapered surfaces. Further, an annular band portion connected to the tapered surface is projected on the outer peripheral surface of the cover member, the annular band portion is locked to the opening end surface of the cylinder tube, and the annular band portion connected to the tapered surface is connected to the outer peripheral surface of the cover member. It protrudes, the annular band is locked to the end surface of the opening end of the cylinder tube, a step is formed on the inner peripheral surface of the joint member, and the step is pressed against the annular band. Further, stainless steel is used as the material of the cylinder tube, and iron is used as the material of the cover member.

  One or a plurality of sensor mounting bars disposed in the longitudinal direction of the outer peripheral surface of the cylinder tube, one or a plurality of proximity sensors mounted at predetermined positions of the sensor mounting bar, using the hydraulic cylinder having the above-described configuration, and a cylinder It consists of a sensor detector mounted on the piston, and the sensor detector mounted on the cylinder piston moves within the cylinder tube in conjunction with the expansion and contraction of the cylinder piston, and detects the position of the proximity sensor mounted on the sensor mounting bar. Provides a hydraulic cylinder for detecting the position of the cylinder piston.

  Then, a plurality of sensor mounting bars are installed at different positions in the circumferential direction of the cylinder tube, and a plurality of sensor mounting bars are installed in the longitudinal direction of the cylinder tube. In addition, a proximity sensor is mounted so that its position can be adjusted, and a ring-shaped magnet mounted on a cylinder piston is used as a sensor detection body.

  Further, a hydraulic cylinder device is provided in which a hydraulic cylinder having the above-described configuration is used to weld a bracket made of the same type of metal as the cylinder tube to the cylinder tube, and the hydraulic unit is integrally mounted on the cylinder tube via the bracket. To do.

  According to the present invention described above, there is no need to use a tie bolt and a welding structure as a structure for fixing the cover member to the head side and rod side end portions of the cylinder tube. Therefore, the effective stroke of the hydraulic cylinder can be efficiently secured, and the cover member can be made of a metal made of a material different from that of the cylinder tube, specifically, iron, thereby reducing the cost of the hydraulic cylinder. can do. In addition, by fitting a cover member having a tapered surface at an intermediate position of the outer periphery of one end portion into the inner peripheral surface of the opening end portion of the cylinder tube in which the tapered surface is formed from the opening end surface, the both tapered surfaces are brought into close contact with each other. An anti-rotation mechanism with both tapered surfaces is formed, and the axial centers of the cylinder tube and the cover member can be easily realized.

  When fixing the cover member, the outer peripheral surface of both the cover member and the opening end of the cylinder tube is covered with a joint member, and the screw groove formed on the inner peripheral surface of the joint member is formed on the outer peripheral surface of the opening end of the cylinder tube. The cover member can be easily fixed because it is structured to be screwed into the screw groove carved in the cover.

  Furthermore, in conjunction with the expansion and contraction of the cylinder piston from the cylinder tube, the sensor detector attached to the cylinder piston moves in the cylinder tube, so that the sensor mounting bar attached to the outer peripheral surface of the cylinder tube can be moved to an arbitrary position. By approaching the installed proximity sensor, the position of the rod corresponding to the installed position of the proximity sensor can be detected. In addition, since the proximity sensor is installed on the outer peripheral surface of the cylinder tube, there is no change in the internal structure of the hydraulic cylinder, and there is no restriction on the structure of the hydraulic cylinder, the material of the cylinder tube used, the pipe diameter, etc. It has versatility that can be attached to existing hydraulic cylinders.

1 is an overall side view of a hydraulic cylinder according to the present invention. FIG. 2 is a longitudinal sectional view of the center part of FIG. 1. FIG. 3 is a longitudinal sectional view of a main part on the head side in FIG. 2. The principal part sectional drawing of the cylinder tube of a head side. The side view of the cover member by the side of a head. The longitudinal cross-sectional view of a coupling member. The principal part longitudinal cross-sectional view by the side of the rod of FIG. 1 is an overall side view of a hydraulic cylinder equipped with a detection device according to the present invention. The whole perspective view of a sensor attachment bar. The whole side view of the sensor attachment bar which attached the sensor. The whole perspective view of the sensor attachment bar which attached the sensor. The whole perspective view of the hydraulic cylinder which attached the bracket for hydraulic units. The whole side view of the hydraulic cylinder which attached the bracket for hydraulic units. 1 is an overall side view of a hydraulic cylinder device according to the present invention. FIG. 15 is an overall perspective view of FIG. 14.

  Embodiments of a hydraulic cylinder and a hydraulic cylinder device according to the present invention will be described below. FIG. 1 is an overall side view of a hydraulic cylinder 1 according to the present invention, FIG. 2 is a longitudinal sectional view of a central portion thereof, and FIG. 3 is a longitudinal sectional view of an essential portion of the head side in FIG. In the figure, the hydraulic cylinder 1 is a non-magnetic body having an opening end located at both ends of a stainless steel cylinder tube 2, that is, an opening end 2a-1 on the head side (see FIG. 4) and an opening end 2a- on the rod side. 2 (see FIG. 7) are sealed with iron cover members 3 and 4 as magnetic bodies, respectively.

  A rod 5 is accommodated in the cylinder tube 2, and a base end portion 5a of the rod 5 located on the head side is formed as a small diameter portion. The cylinder piston 6 is wound around the base end 5a, and the cylinder piston 6 is fixed by screwing a fixing nut 7 into a screw groove 5c formed on the outer periphery of the base end 5a. Reference numeral 8 denotes a collar provided on the outer peripheral surface of the rod 5, which is in close contact with the end surface of the cylinder piston 6 on the rod side. As shown in FIG. 7, the tip 5 b of the rod 5 is extended to the outside from the rod-side cover member 4, and the cylinder piston 6 slides and moves in the cylinder tube 2, so that the cylinder 5 can be expanded and contracted. Is possible. 9a and 9b are hydraulic ports for supplying pressure oil to the head side and the rod side of the cylinder piston 6, respectively.

  The present invention is characterized by a fixing structure of the cover member 3 to the opening end 2a-1 on the head side of the cylinder tube 2 and a fixing structure of the cover member 4 to the opening end 2a-2 on the rod side. The structure will be described with an example of a fixing structure of the cover member 3 on the head side. FIG. 4 is a cross-sectional view of the main part of the cylinder tube 2 on the head side. As shown in the figure, a tapered surface 2c-1 that is inclined in the axial direction of the cylinder tube 2 from the opening end surface 2b-1 is formed at the opening end 2a-1 of the cylinder tube 2. Further, a screw groove 2d-1 is formed on the outer peripheral surface of the opening end 2a-1 from the opening end surface 2b-1.

  FIG. 5 is a side view of the cover member 3 on the head side. A taper surface 3b inclined outward is formed on the outer peripheral surface of the tip portion 3a of the cover member 3, and a taper surface 3b is formed in the opposite direction of the tip portion 3a. An annular band portion 3c protruding outward from the tapered surface 3b is provided on the outer peripheral surface of the cover member 3 so as to be connected. The diameter of the tip 3a of the cover member 3 is substantially the same as the inner diameter of the cylinder tube 2, and the cover member 3 can be fitted from the tip 3a to the opening end 2a-1 of the cylinder tube 2. As a result, as shown in FIG. 3, the annular band portion 3 c of the cover member 3 engages with the opening end surface 2 b-1 of the cylinder tube 2, and the tapered surface 3 b of the cover member 3 and the tapered surface 2 c-of the cylinder tube 2. 1 are close to each other.

  Next, with the tapered surface 3b of the cover member 3 and the tapered surface 2c-1 of the cylinder tube 2 in close contact with each other, the outer peripheral surfaces of both the cover member 3 and the open end 2a-1 of the cylinder tube 2 are shown in FIG. The joint member 10 shown in FIG. The joint member 10 is a hollow cylindrical body, and is provided with a screw groove 10a on the inner peripheral surface, and a step portion 10b is formed on the inner peripheral surface continuously with the screw groove 10a. The screw groove 10a carved on the inner peripheral surface of the joint member 10 is screwed into the screw groove 2d-1 carved on the outer peripheral surface of the opening end 2a-1 of the cylinder tube 2, and the step portion 10b of the joint member 10 is engaged. The cover member 3 is fixed to the open end 2a-1 of the cylinder tube 2 by tightening so as to be in pressure contact with the annular band portion 3c of the cover member 3. In FIG. 3, 22 is an annular seal member attached to the outer periphery of the tip 3 a of the cover member 3, 23 is an annular packing attached to the outer periphery of the cylinder piston, and 24 is a wear ring as a bearing for the cylinder piston 6. is there.

  Therefore, when the cover member 3 is completely fixed to the opening end 2a-1 of the cylinder tube 2, the tapered surface 2c-1 of the cylinder tube 2 and the tapered surface 3b of the cover member 3 are as shown in FIG. The annular band portion 3c of the cover member 3 is engaged with the opening end surface 2b-1 of the cylinder tube 2, and the stepped portion 10b of the joint member 10 is in pressure contact with the annular band portion 3c of the cover member 3. The joint member 10 is screwed into the open end 2a-1 of the cylinder tube 2 by tightening. For this reason, the rotation prevention mechanism between the cylinder tube 2 and the cover member 3 can be formed by the close contact between both the tapered surfaces 2c-1 and 3b, and the axes of the cylinder tube 2 and the cover member 3 can be made to coincide with each other. Further, the annular band portion 3c of the cover member 3 is engaged with the opening end surface 2b-1 of the cylinder tube 2, and positioning can be performed by the stepped portion 10b of the joint member 10 being in pressure contact with the annular band portion 3c. Therefore, excessive tightening of the joint member 10 and insufficient tightening can be prevented by the annular band portion 3c, and the joint member 10 can be screwed into an optimum position.

  In the above description, the fixing structure of the cover member 3 on the head side has been described as an example, but the same configuration is also used to fix the cover member 4 to the opening end 2a-2 on the rod side of the cylinder tube 2. Therefore, the same components are denoted by the same reference numerals and the description thereof is omitted.

FIG. 7 is a longitudinal sectional view of the main part on the rod side. Like the cover member 3 on the head side, the cover member 4 is formed with a tapered surface 4b inclined outward on the outer peripheral surface of the distal end portion 4a. An annular band portion 4c protruding outward from the tapered surface 4b is provided on the outer peripheral surface of the cover member 4 so as to be connected to the tapered surface 4b in the direction opposite to the tip portion 4a. The diameter of the front end portion 4a of the cover member 4 is substantially the same as the inner diameter of the cylinder tube 2, and the cover member 4 can be fitted from the front end portion 4a to the opening end portion 2a-2 on the rod side. As a result, as shown in FIG. 7, the annular band portion 4 c of the cover member 4 engages with the opening end surface 2 b-2 of the cylinder tube 2, and the tapered surface 4 b of the cover member 4 and the tapered surface 2 c-of the cylinder tube 2. 2 are close to each other. Note that the rod 5 is inserted into the cover member 4, and the distal end portion 5 b is extended to the outside so that the cover member 4 can expand and contract.

  Next, a structure for detecting the position of the rod 5 will be described. 8 is an overall side view of the hydraulic cylinder 1 equipped with the detection device according to the present invention, FIG. 9 is an overall perspective view of the sensor mounting bar 11, and FIG. 10 is an overall side view of the sensor mounting bar 11 equipped with the proximity sensor 14. FIG. 11 is an overall perspective view of FIG. In the figure, reference numeral 11 denotes a sensor mounting bar having a predetermined length, and both ends of an insertion port formed in a sensor mounting bracket 12 having a U-shaped cross section disposed so as to face each other in the longitudinal direction of the outer peripheral surface of the cylinder tube 2. The cylinder tube 2 is extended along the longitudinal direction of the cylinder tube 2 by being inserted through the portion and fixed integrally with the sensor mounting bracket 12 by the fixing bolt 13. The sensor mounting bracket 12 is welded to the cylinder tube 2 using nonmagnetic stainless steel.

  The sensor mounting bar 11 can adopt any structure, diameter, and material without being restricted by the structure of the hydraulic cylinder device and the diameter of the cylinder tube 2 to be used, and is highly versatile. In addition, a plurality of sensor mounting bars 11 can be installed at different positions in the circumferential direction of the cylinder tube 2, and a plurality of sensor mounting bars 11 can also be installed in the longitudinal direction of the cylinder tube 2.

  The proximity sensor 14 is a sensor that detects that the detection object is approaching without contact, and in the illustrated example, a magnetic type using a magnet is used. In addition, there is a high-frequency oscillation type using electromagnetic induction, but any type can be used. In the illustrated example, the proximity sensors 14 are arranged in the vicinity of both ends of the sensor mounting bar 11, but the location and number of the sensors are arbitrary, and one or a plurality of proximity sensors 14 are positioned at arbitrary positions on the sensor mounting bar 11. Wear adjustable. The proximity sensor 14 is detachably attached to a sensor fixture 15 that is fixed to the sensor mounting bar 11 so that its position can be adjusted. Since this proximity sensor 14 can be detected in a non-contact manner, it can realize a long life without damaging a detection object or sensor, and can perform reliable detection even in a bad environment where water or oil scatters, and can respond. There is an advantage of high speed.

  And the sensor detection body 16 which consists of a ring-shaped magnet is embed | buried on the outer peripheral surface of the cylinder piston 6 wound around the rod 5 accommodated in the cylinder tube 2. As shown in FIG. The sensor detection body 16 attached to the cylinder piston 6 moves in the cylinder tube 2 in conjunction with the expansion and contraction of the cylinder piston 6, and the sensor detection body 16 in the cylinder tube 2 is moved by the proximity sensor 14 attached to the sensor mounting bar 11. , That is, the position of the cylinder piston 6 can be detected.

  The hydraulic cylinder 1 having the above-described configuration is used, and a bracket 17 made of the same type of metal as the cylinder tube 2, specifically, stainless steel, is welded to the upper outer peripheral surface of the cylinder tube 2 (see FIGS. 12 and 13). By mounting a hydraulic unit 20 incorporating necessary members such as an oil tank 18 and an electric motor 19 for supplying and controlling the pressure oil to the hydraulic cylinder 1 through the bracket 17, the cylinder tube 2 is integrally provided. The hydraulic cylinder device 21 shown in FIG.

  Next, a method for detecting the position of the rod will be described. The sensor detector 16 attached to the cylinder piston 6 moves in the cylinder tube 2 by the expansion and contraction of the cylinder piston 6 of the hydraulic cylinder 1. As the cylinder piston 6 expands and contracts, the sensor detection body 16 in the cylinder tube 2 approaches or separates from the proximity sensor 14 mounted on the sensor mounting bar 11 on the outer peripheral surface of the cylinder tube 2. By detecting that the detection body 16 has approached, the positions of the rod 5 and the cylinder piston 6 can be detected.

  In the illustrated example, two proximity sensors 14 are installed, one at each end of the sensor mounting bar 11, so that the stroke end of the rod 5 can be detected. As an example of control by the proximity sensor 14, for example, in conjunction with the reduction of the rod 5, the sensor detection body 16 moves in the cylinder tube 2 in the direction of the opening end 2 a-1 on the head side, and consists of a ring-shaped magnet. By detecting that the sensor detector 16 has approached the proximity sensor 14, the stroke end of the rod 5 in the direction of the opening end 2 a-1 on the head side is detected. Next, when the sensor detection body 16 moves in the direction of the opening end 2a-2 on the rod side and approaches the proximity sensor 14, the stroke in the direction of the opening end 2a-2 on the rod side of the rod 5 is detected. Detect end. And since the installation position and installation number to the sensor attachment bar 11 of the proximity sensor 14 can be set arbitrarily, the rod 5 can be arbitrarily controlled by adjusting the installation position and installation number of the proximity sensor 14.

  Since the installation position and the number of installation of the proximity sensor 14 can be set arbitrarily, the operation of the rod 5 can be arbitrarily controlled in multiple stages in conjunction with the operation required as an actuator. In addition, the present invention can be applied to a hydraulic cylinder device in which the hydraulic unit 20 is installed separately from the hydraulic cylinder 1, and can be applied to any hydraulic cylinder device. Further, it can be applied to an existing hydraulic cylinder device.

  According to the present invention described above, there is no need to use a tie bolt and a welding structure as a structure for fixing the cover member to the head side and rod side end portions of the cylinder tube. Therefore, the effective stroke of the hydraulic cylinder can be efficiently secured, and the cover member can be made of a metal made of a material different from that of the cylinder tube, specifically, iron, thereby reducing the cost of the hydraulic cylinder. can do. In addition, by fitting a cover member having a tapered surface at an intermediate position of the outer periphery of one end portion into the inner peripheral surface of the opening end portion of the cylinder tube in which the tapered surface is formed from the opening end surface, the both tapered surfaces are brought into close contact with each other. An anti-rotation mechanism with both tapered surfaces is formed, and the axial centers of the cylinder tube and the cover member can be easily realized.

  When fixing the cover member, the outer peripheral surface of both the cover member and the opening end of the cylinder tube is covered with a joint member, and the screw groove formed on the inner peripheral surface of the joint member is formed on the outer peripheral surface of the opening end of the cylinder tube. The cover member can be easily fixed because it is structured to be screwed into the screw groove carved in the cover.

  Furthermore, in conjunction with the expansion and contraction of the cylinder piston from the cylinder tube, the sensor detector attached to the cylinder piston moves in the cylinder tube, so that the sensor mounting bar attached to the outer peripheral surface of the cylinder tube can be moved to an arbitrary position. By approaching the installed proximity sensor, the position of the rod corresponding to the installed position of the proximity sensor can be detected. In addition, since the proximity sensor is installed on the outer peripheral surface of the cylinder tube, there is no change in the internal structure of the hydraulic cylinder, and there is no restriction on the structure of the hydraulic cylinder, the material of the cylinder tube used, the pipe diameter, etc. It has versatility that can be attached to existing hydraulic cylinders.

DESCRIPTION OF SYMBOLS 1 ... Hydraulic cylinder 2 ... Cylinder tube 2a-1 ... Open end part (on the head side) 2b-1 ... Open end face (on the head side) 2c-1 ... Tapered surface on the head side 2d-1 ... (On the head side) ) Screw groove 2a-2 ... Open end 2b-2 (on the rod side) Open end face 2c-2 (on the rod side) Tapered surface 2d-2 ... (on the rod side) Screw groove 3 ... (Head side) cover member 3a ... (head side) tip 3b ... (head side) taper surface 3c ... (head side) annular band 4 ... (rod side) cover member 4a ... (rod side) ) Tip portion 4b ... (Rod side) taper surface 4c ... (Rod side) annular band portion 5 ... Rod 5a ... Base end portion 5b ... Tip portion 5c ... Screw groove 6 ... Cylinder piston 7 ... Fixing nut 8 ... Collar 9a , 9b ... Hydraulic port 10 ... Joint member 10a ... Screw groove DESCRIPTION OF SYMBOLS 10b ... Step part 11 ... Sensor mounting bar 12 ... Sensor mounting bracket 13 ... Fixing bolt 14 ... Proximity sensor 15 ... Sensor fixture 16 ... Sensor detection body 17 ... Bracket 18 ... Oil tank 19 ... Electric motor 20 ... Hydraulic unit 21 ... Hydraulic cylinder apparatus

Claims (12)

A hydraulic cylinder formed by sealing an opening end of a cylinder tube made of a non-magnetic material with a cover member made of a magnetic material,
A cover member having a tapered surface on the outer peripheral surface is fitted into the inner peripheral surface of the opening end portion of the cylinder tube formed with a tapered surface from the opening end surface, and both the tapered surfaces are brought into close contact with each other. Open the cylinder tube by covering both outer peripheral surfaces with a joint member and screwing the screw groove formed on the inner peripheral surface of the joint member with the screw groove formed on the outer peripheral surface of the opening end of the cylinder tube. A hydraulic cylinder, wherein a cover member is fixed to an end portion.   2. The hydraulic cylinder according to claim 1, wherein a rotation prevention mechanism for the cylinder tube and the cover member is formed by close contact between both tapered surfaces.   The hydraulic cylinder according to claim 1 or 2, wherein the axial centers of the cylinder tube and the cover member are matched by close contact between both tapered surfaces.   The hydraulic cylinder according to claim 1, 2 or 3, wherein an annular band portion connected to the taper surface is projected on the outer peripheral surface of the cover member, and the annular band portion is engaged with the end surface of the opening end surface of the cylinder tube.   An annular band connected to the taper surface is projected on the outer peripheral surface of the cover member, the annular band is locked to the end surface of the opening end of the cylinder tube, and a step is formed on the inner peripheral surface of the joint member. The hydraulic cylinder according to claim 1, 2 or 3, wherein the step portion is pressed against the annular belt portion.   The hydraulic cylinder according to claim 1, 2, 3, 4 or 5, wherein stainless steel is used as a material of the cylinder tube and iron is used as a material of the cover member. Using the hydraulic cylinder according to any one of claims 1 to 6,
One or a plurality of sensor mounting bars arranged in the longitudinal direction of the outer peripheral surface of the cylinder tube, one or a plurality of proximity sensors mounted at a predetermined position of the sensor mounting bar, and a sensor detector mounted on the cylinder piston Detecting the position of the cylinder piston by detecting the position of the proximity sensor attached to the sensor mounting bar when the sensor detector attached to the cylinder piston moves in the cylinder tube in conjunction with the expansion and contraction of the cylinder piston. Hydraulic cylinder characterized by   The hydraulic cylinder according to claim 7, wherein a plurality of sensor mounting bars are installed at different positions in the circumferential direction of the cylinder tube.   The hydraulic cylinder according to claim 7 or 8, wherein a plurality of sensor mounting bars are installed in a longitudinal direction of the cylinder tube.   The hydraulic cylinder according to claim 7, 8 or 9, wherein the proximity sensor is mounted so as to be adjustable in position.   The hydraulic cylinder according to claim 7, 8, 9, or 10, wherein a ring-shaped magnet mounted on the cylinder piston is used as the sensor detection body. Using the hydraulic cylinder according to any one of claims 1 to 11,
A hydraulic cylinder device, wherein a cylinder tube is welded with a bracket made of the same type of metal as the cylinder tube, and the hydraulic unit is integrally mounted on the cylinder tube via the bracket.

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