Rotary joint

Abstract

The present invention provides a rotary joint that can suppress adverse effects on the angle measuring section due to the action of drain pressure and prevent damage to the angle measuring section. [Solution] The rotary joint 100 according to the present invention is a rotary joint that rotatably connects two objects and transports fluid, comprising: a cylindrical rotor 120 fixed to one of the objects; a shaft 130 rotatably inserted into the rotor; a hole 132 provided inside the shaft along the central axis of the shaft; a rod 140 provided inside the hole; an angle measuring unit 200 provided at the opening end of the hole for measuring the rotation angle of the rod relative to the shaft; a sensor drain pipe 160 formed at a position corresponding to the angle measuring unit on the shaft and communicating with the hole from the outer surface of the shaft; a drain bolt 180 for sealing the sensor drain pipe; and a resin or rubber drain gasket 182 disposed between the drain bolt and the shaft.

Description

Technical Field

[0001] The present invention relates to a rotary joint.

Background Art

[0002] For example, in construction machines such as hydraulic excavators and crane trucks, a revolving body arranged at the upper part and a traveling body arranged at the lower part are connected by a rotary joint. The rotary joint rotatably connects the revolving body and the traveling body and conveys fluid to them.

[0003] For example, in Patent Document 1, there is disclosed "a rotary joint including a flange, a cylindrical rotor having one end connected to the flange, a shaft having an outer periphery rotatably connected to the inner periphery of the rotor with the central axis of the rotor as a rotation axis, a hole portion which is a drain oil passage formed along the central axis, a discharge hole leading from the hole portion to the outer periphery, a rod provided in the hole portion so as to extend along the central axis from one end side of the shaft and having one end connected to the flange, an angle measuring portion connected to the hole portion so as to face from the other end side of the shaft toward the other end of the rod and measuring a rotation angle with the central axis between the rod and the shaft as a rotation axis, and a shielding member formed in a cup shape, having an outer periphery rotatably connected to the hole portion along the central axis, having the other end of the rod connected to the inner periphery, shielding between the rod and the angle measuring portion in the hole portion, and provided at a distance from the angle measuring portion."

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The rotary joint described in Patent Document 1 is equipped with an "angle measuring unit for measuring the rotation angle." In Patent Document 1, an O-ring attached to a shielding member seals the drain oil acting on the hole, preventing foreign matter flowing through the flow path or foreign matter contained in the oil from adhering to the sensor and reducing the measurement accuracy.

[0006] However, continued use of the rotary joint can cause wear and deterioration of the O-ring, which can no longer completely seal the drain oil due to the drain pressure. This can lead to the drain pressure acting on the angle measuring section, potentially causing damage to the section.

[0007] In view of these problems, the present invention aims to provide a rotary joint that can suppress adverse effects on the angle measuring section due to the action of drain pressure and prevent damage to the angle measuring section. [Means for solving the problem]

[0008] To solve the above problems, the rotary joint according to this embodiment is a rotary joint that rotatably connects two objects and transports fluid, and comprises a cylindrical rotor fixed to one of the objects, a shaft rotatably inserted into the rotor, a hole provided inside the shaft along the central axis of the shaft, a rod provided inside the hole, an angle measuring unit provided at the opening end of the hole for measuring the rotation angle of the rod relative to the shaft, a sensor drain conduit formed at a position corresponding to the angle measuring unit on the shaft and communicating with the hole from the outer surface of the shaft, a drain bolt for sealing the sensor drain conduit, and a resin or rubber drain gasket disposed between the drain bolt and the shaft.

[0009] The drain gasket mentioned above should preferably be made of 66 nylon. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a rotary joint that can suppress adverse effects on the angle measuring section due to the action of drain oil and its drain pressure, and prevent damage to the angle measuring section. [Brief explanation of the drawing]

[0011] [Figure 1] This figure illustrates a construction machine equipped with a rotary joint according to this embodiment. [Figure 2] This is an overall perspective view of the rotary joint of this embodiment. [Figure 3] This is a cross-sectional view AA in Figure 2. [Figure 4] Figure 3 is an enlarged view of the vicinity of the angle measuring section. [Figure 5] Figure 4 is a magnified view of the vicinity of the angle measuring section. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in these embodiments are merely examples to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.

[0013] (Construction machinery 10) Figure 1 is a diagram illustrating a construction machine 10 equipped with a rotary joint 100 according to this embodiment. The rotary joint 100 of this embodiment is a device that rotatably connects two objects and conveys fluid. In the example shown in Figure 1, the rotary joint 100 rotatably connects a traveling body 20 (one object) located at the bottom and a slewing body 30 (the other object) located at the top of a hydraulic excavator, which is a construction machine 10.

[0014] In this embodiment, a hydraulic excavator is used as an example of construction machinery 10, but it is not limited to this. The rotary joint 100 of this embodiment can also be applied to other construction machinery, such as cranes or other machines that operate by hydraulics.

[0015] The traveling body 20 is provided at the lower part of the construction machine 10, supports the entire construction machine 10, and moves the construction machine 10 forward and backward according to control signals, control commands, control operations, etc. transmitted from the driver's cab 32 on the slewing body 30 by the operation of the driver of the construction machine 10.

[0016] The slewing body 30 is provided at the upper part of the traveling body 20, and includes a driver's cab 32 for the driver of the construction machine 10 to board and control the operation of the construction machine 10, and a hydraulic pump 34 for supplying oil to each component that operates by the hydraulic pressure of the construction machine 10. An arm part 40 is connected to the slewing body 30, and oil is supplied from the hydraulic pump 34 to the arm part 40. The arm part 40 is, for example, a multi-joint type hydraulic arm provided with a working part 42 such as a bucket used for civil engineering work at the tip.

[0017] The rotary joint 100 is, for example, a rotary swivel joint, and supplies oil from the slewing body 30 to the traveling body 20. The rotary joint 100 is provided between the traveling body 20 and the slewing body 30, the upper end is connected to the lower part of the slewing body 30, and the lower end is connected to the upper part of the traveling body 20. Also, the rotary joint 100 discharges the drain oil in a hydraulic motor (not shown) provided in the traveling body 20 to a tank (not shown) provided in the slewing body 30.

[0018] (Rotary joint 100) FIG. 2 is an overall perspective view of the rotary joint 100 of the present embodiment. FIG. 3 is a cross-sectional view taken along the line A-A of FIG. 2. In the present embodiment, the central axis direction (the direction perpendicular to the flange 110) of the rotary joint 100 is defined as the Z-axis direction, the short side direction of the flange 110 is defined as the X-axis, and the long side direction is defined as the Y-axis.

[0019] As shown in FIGS. 2 and 3, the rotary joint 100 of the present embodiment includes a flange 110, a rotor 120, a shaft 130, and a rod 140. The flange 110 is a substantially flat plate-like member for fixing the rotary joint 100 to the installation surface of the traveling body 20.

[0020] The rotor 120 is a cylindrical member whose ends are fixed to the flange 110 and fixed to the traveling body 20 (see FIG. 1) via the flange 110. A shaft 130 is rotatably inserted into the rotor 120.

[0021] The rotor 120 supplies the oil flowing in from the shaft 130 to the traveling body 20. For this purpose, the rotor 120 is provided with a plurality of rotor-side ports 122 that serve as flow paths for the oil flowing in from the shaft 130. The oil flowing into the shaft 130 is, for example, supply oil to a hydraulic motor, return oil from the hydraulic motor, and pilot oil.

[0022] The shaft 130 is a member formed in a cylindrical shape. A hole 132 is formed inside the shaft 130 along the central axis O of the shaft 130. The shaft 130 is also provided with a plurality of shaft-side ports 134 for oil to flow between the shaft 130 and the swivel body 30. The shaft-side ports 134 communicate with the rotor-side ports 122 via an oil passage (not shown) provided inside.

[0023] A rod 140 is disposed in the hole 132 of the shaft 130. One end of the rod 140 is connected to the flange 110 by a fixing member 190. A drain oil passage 150 is formed in the gap formed between the shaft 130 and the rod 140. The drain oil flowing into the drain oil passage 150 is discharged from a discharge hole 136 provided on the outer periphery of the shaft 130.

[0024] As shown in FIG. 3, in the rotary joint 100 of the present embodiment, an angle measurement unit 200 is provided at the open end of the hole 132. The angle measurement unit 200 is, for example, a magnetic angle sensor, and measures the rotation angle of the rod 140 with respect to the shaft 130. Also, as will be described in detail later, at a position corresponding to the angle measurement unit 200 of the shaft 130, a sensor unit drain pipe 160 communicating from the outer peripheral surface of the shaft 130 to the hole 132 is formed.

[0025] Figure 4 is an enlarged view of the vicinity of the angle measuring section 200 in Figure 3. A cup-shaped shielding member 170 is connected to the rod 140 by fitting or screwing. The shielding member 170 shields the space between the rod 140 and the angle measuring section 200 within the hole 132 of the shaft 130.

[0026] The shielding member 170 is made of a non-magnetic material. A magnet 172 is provided at the tip of the rod 140, enclosed within the shielding member 170. The magnet 172 is, for example, a permanent magnet and generates a magnetic field. The magnet 172 is used by the angle measuring unit 200 to measure the rotation angle of the rod 140 relative to the shaft 130.

[0027] Furthermore, O-rings 174a and 174b are provided on the outer circumference of the shielding member 170. The O-rings 174a and 174b prevent the drain oil flowing into the drain oil passage 150 from leaking to the angle measuring section 200.

[0028] With the above configuration, the shielding member 170 shields the space between the rod 140 side of the hole 132 and the angle measuring section 200 side. Therefore, the drain pressure from the rod 140 side of the hole 132 is prevented from being applied to the angle measuring section 200, and foreign matter flowing into the drain oil passage 150 is prevented from adhering to the angle measuring section 200. Consequently, the angle measuring section 200 can measure the rotation angle of the rod 140 with high precision.

[0029] Figure 5 is an enlarged view of the vicinity of the angle measuring unit 200 shown in Figure 4, illustrating the disassembled components. The angle measuring unit 200 transmits the measured rotation angle as an electrical signal to the control equipment of the construction machine 10, such as the slewing body 30 or the traveling body 20. As shown in Figure 5, the angle measuring unit 200 is composed of a magnetic sensor 210, a socket 220, and a fixing member 230.

[0030] The magnetic sensor 210 detects magnetic flux using, for example, two magnetic detection elements positioned perpendicular to each other on the measurement surface. The magnetic sensor 210 measures the rotation angle of the rod 140 relative to the shaft 130 from the ratio of the two detected magnetic flux values. The socket 220 is cylindrical and holds the magnetic sensor 210 at one end. The magnetic sensor 210 and the magnet 172 are positioned at a distance (e.g., about 3.0 mm) from each other that allows for the detection of changes in the magnetic field. Signal lines and communication cables (not shown) are inserted into the socket 220. A fixing member 230 for securing the signal lines and communication cables is attached to the other end of the socket.

[0031] As described above, the O-rings 174a and 174b (O-rings) attached to the shielding member 170 shield the space between the rod 140 side and the angle measuring section 200 side of the hole 132. However, if the O-rings wear out or deteriorate due to continued use of the rotary joint 100, they may not be able to completely shield the drain oil, and the drain pressure may act on the angle measuring section 200, potentially causing damage to the angle measuring section 200.

[0032] As described above, in this embodiment, a sensor drain pipe 160 is formed at a position corresponding to the angle measuring section 200 of the shaft 130, communicating with the hole 132 from the outer circumferential surface of the shaft 130 (see Figures 3 and 4). The "position corresponding to the angle measuring section 200" is, more specifically, the space between the O-ring 174a and the magnetic sensor 210. The rotary joint 100 is equipped with a drain bolt 180 that seals the sensor drain pipe 160 and a resin or rubber drain gasket 182 positioned between the drain bolt 180 and the shaft 130.

[0033] A drain bolt is a component generally installed at the bottom of a vehicle's oil pan. When installing a drain bolt in a vehicle, a drain gasket made of a soft metal such as aluminum or copper is used for robustness. However, in this invention, a drain gasket 182 made of resin or rubber is used to actively allow leakage when the drain pressure exceeds a predetermined value (e.g., 1 MPa).

[0034] According to the above configuration, as long as the drain pressure is below a predetermined value, the sensor drain pipe 160 is sealed by the drain bolt 180 and the drain gasket 182. This effectively prevents water and dust from flowing into the sensor drain pipe 160 from the outside.

[0035] On the other hand, if the drain pressure exceeds a predetermined value, the drain gasket 182 deforms due to the drain pressure. This creates a gap between the sensor drain pipe 160 and the drain bolt 180, allowing the drain oil to be discharged. In other words, the drain bolt 180 and the drain gasket 182 function as a simple relief valve. Therefore, the drain pressure applied to the angle measuring unit 200, i.e., the magnetic sensor 210, can be reduced, and their failure can be prevented.

[0036] Furthermore, nylon 66 is preferred as the material used for the drain gasket 182. This makes it possible to obtain high heat resistance in the drain gasket 182.

[0037] Furthermore, when leakage occurs, the drain gasket 182 may be configured to rupture, or the oil may be configured to seep out through the deformed gap.

[0038] Furthermore, various modifications of the drain gasket 182 are conceivable in order to control (mainly lower) the predetermined value at which leakage occurs. In Figures 3 and 4, a plate-shaped annular member like a washer is assumed as the drain gasket 182. Instead of this, it may be cylindrical (sleeve-shaped) to widen the pressure-receiving surface. Alternatively, it may be a washer-shaped member with a slit, like a spring washer, so that the slit widens under internal pressure. It may also be made of foamed resin (foamed nylon) to be easily deformed under internal pressure. Alternatively, it may be a washer-shaped member with shallow grooves in the radial direction to provide a path that reduces the pressure received from the flange of the drain bolt. Alternatively, grooves (similar to a tap for cutting female threads) may be provided in the threads of the drain bolt to make it easier for internal pressure to be applied to the drain gasket 182.

[0039] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. [Industrial applicability]

[0040] This invention can be used as a rotary joint. [Explanation of symbols]

[0041] 10...Construction machine, 20...Traveling body, 30...Slewing body, 32...Operator's cab, 34...Hydraulic pump, 40...Arm section, 42...Working section, 100...Rotating joint, 110...Flange, 120...Rotor, 122...Rotor side port, 130...Shaft, 132...Hole, 134...Shaft side port, 136...Discharge hole, 140...Rod, 150...Drain oil passage, 160...Sensor section drain pipe, 170...Shielding member, 172...Magnet, 174a...O-ring, 174b...O-ring, 180...Drain bolt, 182...Drain gasket, 190...Fixing member, 200...Angle measuring section, 210...Magnetic sensor, 220...Socket, 230...Fixing member, O...Central axis

Claims

1. In a rotary coupling that rotatably connects two objects and transports fluid, A cylindrical rotor fixed to one object, A shaft rotatably inserted into the rotor, A hole provided inside the shaft along the central axis of the shaft, A rod provided within the aforementioned hole, An angle measuring unit is provided at the open end of the hole portion to measure the rotation angle of the rod relative to the shaft, A sensor drain pipe is formed at a position corresponding to the angle measuring portion of the shaft and communicates with the hole portion from the outer surface of the shaft, A drain bolt that seals the drain pipe of the sensor unit, A rotary joint characterized by comprising a drain gasket made of resin or rubber, which is disposed between the drain bolt and the shaft.

2. The rotary joint according to claim 1, characterized in that the drain gasket is made of 66 nylon.

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