JP2019173460A - Rotary joint, industrial machine, and shovel - Google Patents

Abstract

To provide a rotary joint and the like in which relative angle position between two objects relatively rotating from operational state thereof.SOLUTION: A rotary joint includes first oil passage and second oil passage which circulate hydraulic oil between relatively rotating first object and second object. The rotary joint comprises: a case fixed to the first object; a shaft fixed to the second object and inserted into the case in a rotatable state; shaft side first port and shaft side second port provided in the shaft and corresponding to one end of each of the first oil passage and second oil passage; and case side first port and case side second port provided in the case and corresponding to the other end of each of the first oil passage and second oil passage. Angle difference between the shaft side second port and the shaft side first port viewed in one rotation direction is different from angle difference between the case side second port and the case side first port viewed in one rotation direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a rotary joint and the like.

  For example, an industrial machine such as an excavator may be provided with a sensor (for example, an encoder or a camera) that detects a relative rotational position (angular position) between two relatively rotating objects (Patent Literature). 1 etc.).

JP 2017-053627 A

  However, in the configuration using a sensor or the like, the occurrence of a failure or the like cannot be avoided depending on the working environment of an industrial machine such as an excavator, and in some cases, an increase in cost may be unavoidable. Therefore, it is desirable that the relative angular position between two relatively rotating objects can be acquired with a simpler configuration.

  Then, in view of the said subject, it aims at providing the rotary joint etc. which can estimate the relative angular position between two objects which rotate relatively from the operation state.

In order to achieve the above object, in one embodiment of the present invention,
A rotary joint including a first oil passage and a second oil passage for allowing hydraulic oil to flow between a first object and a second object that rotate relatively;
A case fixed to the first object;
A shaft fixed to the second object and inserted into the case in a rotatable state;
A shaft-side first port and a shaft-side second port provided on the shaft and corresponding to one end of each of the first oil passage and the second oil passage;
A case-side first port and a case-side second port provided in the case, corresponding to the other ends of the first oil passage and the second oil passage,
With reference to the rotational axis of the shaft, the angular difference from the shaft-side second port viewed in one rotation direction from the shaft-side first port, and the case-side first port viewed in the one rotation direction. The angle difference with the case side second port is different.
A rotary joint is provided.

In another embodiment of the present invention,
The rotary joint described above,
Provided in either the first object or the second object, hydraulic oil is supplied through one of the first oil path and the second oil path, and the first oil path And a hydraulic actuator operable in two directions by discharging hydraulic oil through either one of the second oil passages, and
A control device,
The control device is based on a pressure difference between the case side first port and the shaft side first port, and a pressure difference between the case side second port and the shaft side second port, Obtaining a relative angle between the first object and the second object;
Industrial machinery is provided.

In still another embodiment of the present invention,
An excavator as an industrial machine as described above,
A traveling body as the first object;
A revolving body as the second object;
A hydraulic motor as the hydraulic actuator for driving the traveling body,
An excavator is provided.

  According to the above-described embodiment, it is possible to provide a rotary joint or the like that can estimate a relative angular position between two objects that rotate relatively from the operation state.

It is a side view which shows an example of an shovel. It is a block diagram which shows an example of a structure of an shovel. It is a perspective exploded view showing an example of a rotary joint. It is a top view which shows an example of a rotary joint. It is side surface sectional drawing which shows an example of a rotary joint. It is a figure which shows the relationship between the turning angle of an upper turning body, and the flow of the hydraulic oil inside a rotary joint. It is a figure which shows the relationship between the pressure difference between each both ends of two internal oil paths connected to a driving | running | working hydraulic motor, and a turning angle.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

[Outline of excavator]
First, an outline of the excavator 100 will be described with reference to FIG.

  FIG. 1 is a side view showing an example (excavator 100) of an excavator according to the present embodiment.

  An excavator 100 (an example of an industrial machine) according to the present embodiment includes a lower traveling body 1, an upper revolving body 3 that is rotatably mounted on the lower traveling body 1 via a turning mechanism 2, and a boom 4 as an attachment. The arm 5, the bucket 6, and the cabin 10 are provided.

  The lower traveling body 1 (an example of a traveling body) includes, for example, a pair of left and right crawlers, and each crawler is hydraulically driven by traveling hydraulic motors 1A and 1B (see FIG. 2) to cause the excavator 100 to travel.

  The upper swing body 3 (an example of the swing body) is rotated with respect to the lower traveling body 1 by being driven by a swing hydraulic motor 2A (see FIG. 2).

  The boom 4 is pivotally attached to the center of the front part of the upper swing body 3 so that the boom 4 can be raised and lowered. An arm 5 is pivotally attached to the tip of the boom 4 and a bucket 6 is vertically attached to the tip of the arm 5. It is pivotally attached so that it can rotate. The boom 4, the arm 5, and the bucket 6 are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9 as hydraulic actuators, respectively.

  The cabin 10 is a cockpit in which an operator is boarded, and is mounted, for example, on the left side of the front part of the upper swing body 3.

[Configuration of excavator]
Next, the basic configuration of the excavator 100 according to the present embodiment will be described with reference to FIG. 2 in addition to FIG.

  FIG. 2 is a block diagram illustrating an example of the configuration of the excavator 100 according to the present embodiment.

  In the figure, the mechanical power system is indicated by a double line, the high-pressure hydraulic line is indicated by a thick solid line, the pilot line is indicated by a broken line, and the electric drive / control system is indicated by a thin solid line.

  The hydraulic drive system of the excavator 100 according to the present embodiment includes an engine 11, a main pump 14, a control valve 17, and a rotary joint 40. Further, as described above, the hydraulic drive system according to the present embodiment is a traveling hydraulic motor 1A, 1B (hydraulic pressure) that hydraulically drives each of the lower traveling body 1, the upper swing body 3, the boom 4, the arm 5, and the bucket 6. An actuator, an example of a hydraulic motor), a swing hydraulic motor 2A, a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9. Hereinafter, some or all of the traveling hydraulic motors 1A and 1B, the swing hydraulic motor 2A, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 may be referred to as “hydraulic actuators” for convenience.

  The engine 11 is a driving force source of the excavator 100, and is mounted on the rear part of the upper swing body 3, for example. The engine 11 is, for example, a diesel engine that uses light oil as fuel. A main pump 14 and a pilot pump 15 are connected to the output shaft of the engine 11. The engine 11 rotates at a predetermined set rotational speed under the control of an engine control device 75 (Engine Control Module: ECM). Specifically, the ECM 75 has a small difference between the measured rotational speed of the engine 11 taken from the engine rotational speed sensor 11a and the set rotational speed in response to a command related to the set rotational speed input from the controller 30 ( The fuel injection device of the engine 11 is controlled so that it becomes zero.

  The main pump 14 is mounted, for example, at the rear part of the upper swing body 3 and supplies hydraulic oil to the control valve 17 through the high-pressure hydraulic line 16. The main pump 14 is driven by the engine 11 as described above. The main pump 14 is, for example, a variable displacement hydraulic pump, and the stroke length of the piston is adjusted by adjusting the angle (tilt angle) of the swash plate by a regulator under the control of the controller 30, and the discharge amount (Discharge pressure) can be controlled.

  The control valve 17 is, for example, a hydraulic control device that is mounted in the central portion of the upper swing body 3 and controls the hydraulic drive system in accordance with an operation performed on the operation device 26 by an operator. Specifically, the control valve 17 controls the supply and discharge of the hydraulic oil to and from the respective hydraulic actuators according to the operation on the operation device 26 by the operator. The traveling hydraulic motors 1A and 1B, the swing hydraulic motor 2A, the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, and the like are connected to the control valve 17 via a high-pressure hydraulic line. The control valve 17 is provided between the main pump 14 and each hydraulic actuator, and controls a plurality of control valves (direction control valves) that control the flow rate and flow direction of hydraulic oil supplied from the main pump 14 to each hydraulic actuator. )including.

  The rotary joint 40 is provided in the vicinity of the turning center, that is, in the vicinity of the turning mechanism 2 (swing circle), and is a lower traveling body that rotates relative to the turning center axis of the upper turning body 3 (the angular position changes). The hydraulic oil is allowed to flow between 1 and the upper swing body 3. Specifically, the rotary joint 40 includes internal oil passages L <b> 1 to L <b> 4 that allow hydraulic oil to flow between the lower traveling body 1 and the upper swing body 3. One end of each of the internal oil passages L1 and L2 (an example of the first oil passage and the second oil passage) is connected to the control valve 17, and the other end is connected to two ports of the traveling hydraulic motor 1A. . The internal oil passages L3 and L4 have one end connected to the control valve 17 and the other end connected to two ports of the traveling hydraulic motor 1B. That is, one of the internal oil passages L1 and L2 supplies hydraulic oil from the control valve 17 to the traveling hydraulic motor 1A, and the other discharges the hydraulic oil from the traveling hydraulic motor 1A. Further, one of the internal oil passages L3 and L4 supplies hydraulic oil from the control valve 17 to the traveling hydraulic motor 1B, and the other discharges hydraulic oil from the traveling hydraulic motor 1B. Details of the structure of the rotary joint 40 will be described later (see FIGS. 3A to 3C).

  The operation system of the excavator 100 according to the present embodiment includes a pilot pump 15, an operation device 26, and an operation pressure sensor 29.

  The pilot pump 15 is mounted, for example, at the rear part of the upper swing body 3 and supplies pilot pressure to the operating device 26 via the pilot line 25. The pilot pump 15 is, for example, a fixed displacement hydraulic pump, and is driven by the engine 11 as described above.

  The operating device 26 is an operating means that is provided in the vicinity of the cockpit of the cabin 10 and that allows the operator to operate the respective operating elements (the lower traveling body 1, the upper swing body 3, the boom 4, the arm 5, the bucket 6, and the like). . In other words, the operating device 26 operates the hydraulic actuators (travel hydraulic motors 1A and 1B, swing hydraulic motor 2A, boom cylinder 7, arm cylinder 8, and bucket cylinder 9, etc.) that drive the operating elements. It is an operation means to perform. The operating device 26 is connected to the control valve 17 via a hydraulic line 27. Thereby, a pilot signal (pilot pressure) corresponding to the operation state of the lower traveling body 1, the upper swing body 3, the boom 4, the arm 5, the bucket 6 and the like in the operating device 26 is input to the control valve 17. . Therefore, the control valve 17 can drive each hydraulic actuator according to the operating state of the operating device 26. The operating device 26 is connected to an operating pressure sensor 29 via a hydraulic line 28.

  The control system of the shovel 100 according to this example includes a controller 30, an operation pressure sensor 29, pressure sensors 50, 52, 54, and 56, and a turning angle sensor 60.

  The controller 30 (an example of a control device) is a main control device that is provided inside the cabin 10 and performs drive control of the excavator 100, for example. The function of the controller 30 may be realized by arbitrary hardware, software, or a combination thereof. The controller 30 is mainly a microcomputer including a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a nonvolatile auxiliary storage device, various input / output interfaces, and the like. Composed. The controller 30 realizes various functions by executing, on the CPU, one or more programs stored in, for example, a ROM or a nonvolatile auxiliary storage device.

  For example, the controller 30 transmits, to the ECM 75, a control command that causes the engine 11 to rotate at a constant speed that matches the work mode and the set rotational speed in accordance with the work mode and the set rotational speed set by the operator or the like.

  For example, the controller 30 measures the turning angle of the upper turning body relative to the lower traveling body 1 based on the detection signal input from the turning angle sensor 60.

  Further, for example, when the turning angle sensor 60 is in an abnormal state due to a failure or the like, the controller 30 detects pressures near both ends of the internal oil passages L1 and L2 of the rotary joint 40 detected by the pressure sensors 50, 52, 54, and 56. Based on the above, the turning angle of the upper turning body 3 relative to the lower traveling body 1 is measured (estimated). At this time, the controller 30 may determine that the turning angle sensor 60 is abnormal, for example, when the voltage value corresponding to the detection signal captured from the turning angle sensor 60 is not within a normal range. A specific method for estimating the turning angle will be described later (see FIGS. 4 and 5).

  As described above, the operation pressure sensor 29 is connected to the operation device 26 via the hydraulic line 28 and corresponds to the pilot pressure on the secondary side of the operation device 26, that is, the operation state of each operation element in the operation device 26. Detect the pilot pressure. The operation pressure sensor 29 is connected to the controller 30, and the lower traveling body 1 (traveling hydraulic motors 1A and 1B), the upper swinging body 3 (turning hydraulic motor 2A), the boom 4 (boom cylinder 7), and the arm 5 in the operating device 26. A pressure signal (pressure detection value) corresponding to the operation state of (arm cylinder 8), bucket 6 (bucket cylinder 9), and the like is taken into the controller 30. Thereby, the controller 30 can grasp | ascertain the operation state of the lower traveling body 1, the upper turning body 3, and the attachment (the boom 4, the arm 5, and the bucket 6) of the shovel 100.

  The pressure sensors 50, 52, 54, and 56 detect the pressure of the hydraulic oil near both ends of the internal oil passages L1 and L2 of the rotary joint 40, respectively.

  Specifically, the pressure sensor 50 detects the pressure of hydraulic oil near one end (end on the control valve 17 side) of the internal oil passage L1, in other words, near the port 420a of the rotary joint 40 described later. The pressure sensor 52 detects the pressure of hydraulic oil near the other end of the internal oil passage L1 (end on the traveling hydraulic motor 1A side), in other words, near the port 410a of the rotary joint 40 described later. The pressure sensor 54 detects the pressure of hydraulic oil near one end (end on the control valve 17 side) of the internal oil passage L2, in other words, near the port 420b of the rotary joint 40 described later. The pressure sensor 56 detects the pressure of hydraulic oil near the other end of the internal oil passage L2 (end on the traveling hydraulic motor 1A side), in other words, near the port 410b of the rotary joint 40 described later.

  The pressure sensors 50, 52, 54, 56 are mounted, for example, in such a manner that they are incorporated in the vicinity of both ends of the internal oil passages L 1, L 2 of the rotary joint 40. The pressure sensors 50, 52, 54, and 56 are attached to pipes corresponding to high-pressure hydraulic lines connected to the end portions of the internal oil passages L1 and L2 of the rotary joint 40, flanges of attachment portions of the pipe and the rotary joint, and the like. May be.

  A detection signal corresponding to the pressure detected by the pressure sensors 50, 52, 54, 56 is taken into the controller 30. At this time, signals from the pressure sensors 52 and 56 on the lower traveling body 1 side may be taken into the controller 30 by wireless communication based on a predetermined communication method, or between the lower traveling body 1 and the upper swing body 3. It may be taken into the controller 30 by wired communication through a signal line that passes through a rotating contact between them.

  The turning angle sensor 60 detects the turning angle of the upper turning body 3 with respect to the lower traveling body 1. The turning angle sensor 60 can include, for example, a rotary encoder, a resolver, a gyro sensor, a 6-axis sensor, an IMU (Inertial Measurement Unit). The turning angle sensor 60 is connected to the controller 30, and a detection signal corresponding to the detected turning angle of the upper turning body 3 is taken into the controller 30.

[Rotary joint structure]
Next, the structure of the rotary joint 40 will be described with reference to FIG. 3 (FIGS. 3A to 3C).

  In the drawing, a known seal structure between the case 41 and the shaft 42 is omitted, and a description thereof is also omitted. Further, in the drawing, for example, other oil passages such as a drain oil passage are omitted for the sake of simplicity, and description thereof is also omitted.

  FIG. 3A is an exploded perspective view showing an example of the rotary joint 40. FIG. 3B is a plan view showing an example of the rotary joint 40. FIG. 3C is a side cross-sectional view showing an example of a rotary joint, and more specifically, a cross-sectional view of a cross section of a line portion in FIG.

  The rotary joint 40 includes a case 41 and a shaft 42 that is rotatably inserted into the case 41.

  The case 41 is attached to the lower traveling body 1, for example. The case 41 has a substantially cylindrical shape with one end (lower end) closed, and the shaft 42 is inserted into the hollow portion inside.

  The shaft 42 is attached to the upper swing body 3, for example. The shaft 42 has a substantially cylindrical shape that is substantially the same diameter as or slightly smaller than the hollow portion of the case 41, and is inserted into the hollow portion of the case 41 from above. Accordingly, the shaft 42 fixed to the upper swing body 3 is rotated in the hollow portion of the case 41 in conjunction with the swing of the upper swing body 3 with respect to the case 41 fixed to the lower traveling body 1. Can do.

  The shaft 42 has a port 420 corresponding to one end of the internal oil passages L1 to L4 on the control valve 17 (upper swing body 3) side on the upper end surface. The port 420 includes a port 420a (an example of a case side first port) corresponding to one end of the internal oil passage L1, a port 420b (an example of the case side second port) corresponding to one end of the internal oil passage L2, and an internal oil. A port 420c corresponding to one end of the path L3 and a port 420d corresponding to one end of the internal oil path L4 are included.

  As shown in FIG. 3B, the ports 420a to 420d are arranged at positions having substantially the same diameter with reference to the rotation axis AX of the shaft 42 (that is, the turning center axis of the upper turning body 3). Further, the ports 420a to 420d are arranged in the order of 90 ° in the clockwise direction with respect to the rotation axis AX of the shaft 42 in plan view (viewed from above).

  Moreover, the shaft 42 has the groove part 421 dug with the same depth by the radial direction in the perimeter in the side part. The groove part 421 includes groove parts 421a to 421d. The groove portions 421a to 421d are arranged at equal intervals along the rotation axis AX in order from the lower side of the shaft.

  Moreover, the shaft 42 has a communication path that communicates between the ports 420a to 420d and the groove portions 421a to 421d.

  Specifically, as shown in FIG. 3C, the communication path 422a is drilled downward from the port 420a along the rotation axis AX and in a direction along the rotation axis AX (hereinafter referred to as “rotation axis direction”). It has a substantially L shape that is drilled radially outward from the same position as the groove 421a. Thereby, the communicating path 422a connects the port 420a and the groove part 421a.

  The communication path 422b has a substantially L shape that is drilled downward along the rotation axis AX from the port 420b and is drilled radially outward from the same position as the groove 421b in the rotation axis direction. Thereby, the communication path 422b connects the port 420b and the groove part 421b.

  Further, similarly to the communication paths 422a and 422b, a substantially L-shaped communication path (not shown) is formed between the port 420c and the groove part 421c and between the port 420d and the groove part 421d.

  The outer surface of the case 41 corresponds to the other end of the internal oil passages L1 to L4 on the side of the traveling hydraulic motors 1A and 1B (lower traveling body 1), and is between the outer surface of the case 41 and the inner surface (hollow space). A port 410 that communicates with each other is provided. The port 410 includes a port 410a (an example of a case-side first port) corresponding to the other end of the internal oil passage L1, a port 410b (an example of the case-side second port) corresponding to the other end of the internal oil passage L2, A port 410c corresponding to the other end of the internal oil passage L3 and a port 410d corresponding to the other end of the internal oil passage L4 are included.

  As shown in FIG. 3B, among the ports 410, the ports 410a, 410c and the port 410 are arranged at opposite positions, that is, angular positions with an interval of 180 ° with respect to the rotation axis AX of the shaft 42.

  3C, the port 410a is provided at the same position as the groove 421a in the rotation axis direction (vertical direction) of the shaft 42. Thus, the port 410a is connected to the groove 421a and communicates with the port 420a through the communication path 422a in the shaft 42. That is, the internal oil passage L1 includes the communication passage 422a and the groove portion 421a. The relationship between the angular position of the connecting portion between the communication path 422a and the groove portion 421a with respect to the rotational axis AX of the shaft 42, that is, the angular position of the port 420a and the angular position of the port 410a is the rotational state of the shaft 42, That is, it changes according to the turning state (turning angle) of the upper swing body 3. Although the hydraulic oil can flow in the right direction and the left direction in the plan view in the groove portion 421a, most of the hydraulic oil is in the direction in which the distance between the port 410a and the communication path 422a is short, that is, the difference in angular position is small. It is thought to flow through. Therefore, the length of the portion of the groove portion 421a through which most of the hydraulic oil flows becomes longer or shorter depending on the turning state of the upper turning body 3, and the operation that flows through the internal oil passage L1 according to the length thereof. Oil pressure loss also changes. The same applies to the relationship regarding the angular position with reference to the rotation axis AX between the ports 420b to 420d and the ports 410b to 410d in the internal oil passages L2 to L4.

  The port 410b is provided at the same position as the groove portion 421b in the rotation axis direction of the shaft 42. Thereby, the port 410b is connected to the groove portion 421b and communicates with the port 420b through the communication path 422b in the shaft 42. That is, the internal oil passage L2 includes the communication passage 422b and the groove portion 421b.

  The port 410c is provided at the same position as the groove 421c in the rotation axis direction of the shaft 42. As a result, the port 410c is connected to the groove 421c and communicates with the port 420c through the communication path (not shown). That is, the internal oil passage L3 includes the communication passage and the groove portion 421c.

  The port 410d is provided at the same position as the groove portion 421d in the rotation axis direction of the shaft 42. Thereby, the port 410d is connected to the groove portion 421c, and communicates with the port 420d through the communication path (not shown). That is, the internal oil passage L4 includes the communication passage and the groove portion 421d.

[Turning angle estimation method]
Next, a method for estimating the turning angle of the upper turning body 3 will be described with reference to FIGS.

  FIG. 4 is a diagram showing the relationship between the turning angle of the upper turning body 3 and the flow of hydraulic oil inside the rotary joint 40. Specifically, FIG. 4 shows the rotary joint 40 at a specific turning angle of the upper swing body 3 (left turn 135 °, left turn 45 °, turn 0 °, right turn 45 °, right turn 120 °). It is a figure which shows the flow of the hydraulic fluid of internal oil path L1, L2. FIG. 5 is a diagram showing the relationship between the pressure difference between both ends of each of the two internal oil passages L1, L2 connected to the traveling hydraulic motor 1A and the turning angle.

  FIG. 4 schematically shows the flow of hydraulic oil in the internal oil passage L1 between the port 410a and the port 420a and the flow of hydraulic oil in the internal oil passage L1 between the port 410b and the port 420b. For convenience, the portions corresponding to the respective groove portions 421a and 421b of the internal oil passages L1 and L2 are shown in an overlapping manner. The direction of the hydraulic oil flowing through the internal oil passages L1 and L2 differs depending on the rotational direction of the traveling hydraulic motor 1A. In FIG. 4, for the sake of convenience, the hydraulic oil is supplied to the traveling hydraulic motor 1A through the internal oil passage L2. Then, the state in which the hydraulic oil is discharged from the traveling hydraulic motor 1A by the internal oil passage L1 is shown. FIG. 5 shows a state in which the traveling hydraulic motor 1A is operating, that is, the operating oil is supplied to the traveling hydraulic motor 1A and the operating oil is discharged from the traveling hydraulic motor 1A.

  As shown in FIG. 4, in the case of turning 0 ° in which the front where the attachment of the upper swing body 3 extends and the forward direction of the lower traveling body 1 are aligned, the port is based on the rotation axis AX of the shaft 42. The difference between the angular position of 410a and the angular position of the port 420a is 90 °. Therefore, in this case, most of the hydraulic oil that flows through the internal oil passage L1 flows through the groove portion 421a by a quarter of the circumference. On the other hand, the difference between the angular position of the port 410b and the angular position of the port 420b with respect to the rotational axis AX of the shaft 42 is 180 °. Therefore, in this case, the working oil flowing through the internal oil passage L2 flows in the circumferential direction in the groove portion 421b by a half turn.

  Further, in the case of 45 [deg.] Left turn, the shaft 42 fixed to the upper swing body 3 rotates 45 [deg.] Left from the turn 0 [deg.]. In this case, the difference between the angular position of the port 410a and the angular position of the port 420a with reference to the rotational axis AX of the shaft 42 is increased by 45 ° to 135 °. Therefore, in this case, most of the hydraulic oil flowing through the internal oil passage L1 flows through the groove portion 421a by 3/8 round (135 °) in the circumferential direction. On the other hand, the difference between the angular position of the port 410b and the angular position of the port 420b with respect to the rotational axis AX of the shaft 42 is reduced by 45 ° to 135 °. Therefore, in this case, most of the hydraulic oil flowing through the internal oil passage L2 flows in the circumferential direction in the groove portion 421b by the same 3/8 round (135 °) as in the case of the internal oil passage L1.

  In the case of a left turn of 135 °, the shaft 42 rotates 135 ° to the left from the turn of 0 °. In this case, the difference between the angular position of the port 410a and the angular position of the port 420a with respect to the rotational axis AX of the shaft 42 becomes 180 ° at the maximum when the shaft 42 rotates 90 °, and further rotates 45 °. Therefore, it becomes 135 degrees. Therefore, in this case, most of the hydraulic oil flowing through the internal oil passage L1 flows in the circumferential direction in the groove portion 421a by 3/8 round (135 °). On the other hand, the difference between the angular position of the port 410b and the angular position of the port 420b with respect to the rotation axis AX of the shaft 42 is reduced by 135 ° to 45 °. Therefore, in this case, most of the hydraulic oil that flows through the internal oil passage L2 flows in the circumferential direction by 1/8 turn (45 °) in the groove portion 421b.

  Further, in the case of 45 ° right turn, the shaft 42 rotates 45 ° to the right from 0 ° turn. In this case, the difference between the angular position of the port 410a and the angular position of the port 420a with respect to the rotation axis AX of the shaft 42 is reduced by 45 ° to 45 °. Therefore, most of the hydraulic oil flowing through the internal oil passage L1 flows in the circumferential direction by 1/8 turn (45 °) in the groove portion 421a. On the other hand, the difference between the angular position of the port 410b and the angular position of the port 420b with respect to the rotational axis AX of the shaft 42 is reduced by 45 ° to 135 °. Therefore, in this case, most of the hydraulic oil that flows through the internal oil passage L2 flows in the circumferential direction by 3/8 round (135 °) in the groove portion 421b.

  In the case of a right turn of 120 °, the shaft 42 rotates 120 ° to the right from the turn of 0 °. In this case, the difference between the angular position of the port 410a and the angular position of the port 420a with respect to the rotational axis AX of the shaft 42 becomes 0 ° at the minimum when the shaft 42 rotates 90 °, and further rotates 30 °. By doing so, it becomes 30 °. Therefore, in this case, most of the hydraulic oil flowing through the internal oil passage L1 flows through the groove portion 421a by 1/12 round (30 °) in the circumferential direction. On the other hand, the difference between the angular position of the port 410b and the angular position of the port 420b with respect to the rotation axis AX of the shaft 42 is reduced by 120 ° to 60 °. Therefore, in this case, most of the hydraulic oil flowing through the internal oil passage L2 flows in the circumferential direction by 1/6 round (60 °) in the groove portion 421b.

  Thus, most of the hydraulic oil in the internal oil passages L1 and L2 flows in the circumferential direction in the groove portion 421 (421a, 421b) according to the turning state of the upper swing body 3, that is, the rotation state of the shaft 42. The length (angle) of each part changes. At this time, as described above, since the change in the internal oil passages L1 and L2 has a phase difference, the groove 421 in the internal oil passages L1 and L2 is operated in the circumferential direction according to the change in the turning angle. The relative relationship of the length (angle) of the part through which oil flows also changes.

  Specifically, the angle difference between the port 410a and the port 420a with respect to the rotation axis AX of the shaft 42 increases from 0 ° to 180 ° when the shaft 42 rotates in one direction, and 180 ° It changes in a manner that repeats decreasing from 0 to 0 °. Therefore, the pressure loss generated in the internal oil passages L1 and L2, that is, the pressure difference between the ports 410a and 420a at both ends of the internal oil passage L1, and the ports 410b and ports at both ends of the internal oil passage L2 Similarly, when the hydraulic oil is supplied to and discharged from the traveling hydraulic motor 1A, the pressure difference with 420b corresponds to one rotation of the shaft 42, that is, one rotation of the upper swing body 3 in the shaft 42. This is a mode of increasing / decreasing between a minimum value corresponding to an angle difference of 0 ° between ports relative to the rotation axis AX and a maximum value corresponding to an angle difference of 180 ° between ports.

  On the other hand, with respect to the rotational axis AX of the shaft 42, the angle difference between the port 420a on the upper swing body 3 side and the port 420b viewed in the right direction in plan view is 90 ° as described above. The angle difference between the port 410a on the lower traveling body 1 side and the port 410b viewed in the right direction in plan view is 180 ° as described above. Therefore, there is about 90 ° between the change in the angle difference between the port 410a and the port 420a with respect to the rotation axis AX of the shaft 42 and the change in the angle difference between the port 410b and the port 420b. A phase difference occurs.

  Therefore, as shown in FIG. 5, the graphs 501 and 502 showing the pressure difference between both ends of the internal oil passages L1 and L2 similarly show the maximum value and the minimum value of the pressure difference according to the turning angle. The phase difference of 90 ° occurs in the change.

  Note that there is a difference in the lengths of the communication passages 422a and 422b between the internal oil passages L1 and L2, but the difference is a difference in a straight line portion drilled in the direction of the rotation axis of the shaft 42. Therefore, the influence on the pressure difference between both ends of the internal oil passages L1 and L2 is sufficiently smaller than the change in the portion where most of the hydraulic oil flows through the groove portions 421a and 421b due to the angle difference between the ports.

  Therefore, the controller 30 uses this phase difference, the pressure difference between both ends of the internal oil passage L1, and the pressure difference between both ends of the internal oil passage L2, that is, the difference between the detection values of the pressure sensors 50 and 52, Based on the difference between the detection values of the pressure sensors 54 and 56, the turning angle of the upper turning body 3 relative to the lower traveling body 1 can be estimated (measured). Specifically, since the absolute value of the pressure difference changes depending on the load state of the traveling hydraulic motor 1A, for example, the controller 30 determines the pressure difference between both ends of the internal oil passage L1 and the pressure between both ends of the internal oil passage L2. Based on the ratio to the difference, the turning angle of the upper turning body 3 is estimated. In addition, the controller 30 determines the load state of the traveling hydraulic motor 1A based on the operation state of the traveling hydraulic motor 1A with respect to the operation device 26, and estimates (estimates) the turning angle of the upper swing body 3 in consideration of the load state. )

  As described above, the rotary joint 40 according to the present embodiment has a relative relationship between the two objects that rotate relative to the operating state, specifically, the state of pressure loss between both ends of the internal oil passages L1 and L2. A correct angular position can be estimated. Thereby, the controller 30 can acquire the turning angle of the upper turning body 3 even when the turning angle sensor 60 is in an abnormal state.

  The angle difference with reference to the rotation axis AX of the shaft 42 between the ports of the internal oil passages L3 and L4 also has a phase difference of 90 ° as in the case of the internal oil passages L1 and L2. Therefore, the controller 30 estimates the turning angle of the upper swing body 3 using the pressure difference between the ports of the internal oil passages L3 and L4 instead of the pressure difference between the ports of the internal oil passages L1 and L2. Also good. Further, the controller 30 estimates the turning angle of the upper swing body 3 using the pressure difference between the ports of the internal oil passages L3 and L4 in addition to the pressure difference between the ports of the internal oil passages L1 and L2. Also good. Thereby, the estimation precision of the turning angle of the upper turning body 3 can be improved.

  Further, the arrangement of the ports 420a and 420b on the one end (upper swing body 3) side of the internal oil passages L1 and L2 and the arrangement of the ports 410a and 410b on the other end side (lower traveling body 1) side have the above-described phase difference. Any mode may be set as long as it occurs. That is, with reference to the rotation axis AX of the shaft 42, the angle difference between the port 420b viewed in one rotation direction (right or left) from the port 420a and the port 410b viewed in the same rotation direction from the port 410a. It suffices if the angle difference is different.

[Improvements / deformations]
As mentioned above, although the form for implementing this invention was explained in full detail, this invention is not limited to this specific embodiment, In the range of the summary of this invention described in the claim, various Can be modified or changed.

  For example, in the above-described embodiment, the turning angle is obtained by utilizing the pressure difference between two internal oil passages that supply hydraulic oil to the traveling hydraulic motors 1A and 1B and discharge hydraulic oil from the traveling hydraulic motors 1A and 1B. However, the present invention is not limited to this mode. More specifically, the second traveling body 1 is mounted on the lower traveling body 1 and connected to another hydraulic actuator that can move in two directions from which the hydraulic oil is discharged according to the supply of the hydraulic oil (that is, double-acting type). The turning angle may be estimated using the pressure difference between the two internal oil passages.

  In the above-described embodiments and modifications, the rotary joint 40 is mounted on the excavator 100. However, a similar rotary joint supplies hydraulic oil to a double-acting hydraulic actuator between two relatively rotating objects. It may be mounted on other industrial machines to be discarded. Thereby, as described above, the control device for the industrial machine is connected between the two objects that rotate relatively based on the pressure difference between the two internal oil passages of the rotary joint, which is connected to the hydraulic actuator. A relative rotational position (angular position) can be estimated.

1 Lower traveling body (first object, traveling body)
1A, 1B Traveling hydraulic motor (hydraulic actuator, hydraulic motor)
2A swing hydraulic motor 3 upper swing body (second object, swing body)
4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 14 Main pump 15 Pilot pump 17 Control valve 26 Operating device 29 Operating pressure sensor 30 Controller (control device)
40 Rotary joint 41 Case 42 Shaft 50, 52, 54, 56 Pressure sensor 60 Turning angle sensor 75 Engine control device 100 Excavator (industrial machine)
410a port (case side first port)
410b port (case side second port)
420a port (shaft side first port)
420b Port (second shaft side port)
AX Rotating shaft L1 Internal oil passage (first oil passage)
L2 Internal oil passage (second oil passage)

Claims (4)

A rotary joint including a first oil passage and a second oil passage for allowing hydraulic oil to flow between a first object and a second object that rotate relatively;
A case fixed to the first object;
A shaft fixed to the second object and inserted into the case in a rotatable state;
A shaft-side first port and a shaft-side second port provided on the shaft and corresponding to one end of each of the first oil passage and the second oil passage;
A case-side first port and a case-side second port provided in the case, corresponding to the other ends of the first oil passage and the second oil passage,
With reference to the rotational axis of the shaft, the angular difference from the shaft-side second port viewed in one rotation direction from the shaft-side first port, and the case-side first port viewed in the one rotation direction. The angle difference with the case side second port is different.
Rotary joint. A rotary joint according to claim 1;
Provided in either the first object or the second object, hydraulic oil is supplied through one of the first oil path and the second oil path, and the first oil path And a hydraulic actuator operable in two directions by discharging hydraulic oil through either one of the second oil passages, and
A control device,
The control device is based on a pressure difference between the case side first port and the shaft side first port, and a pressure difference between the case side second port and the shaft side second port, Obtaining a relative angle between the first object and the second object;
Industrial machinery. A sensor for detecting a relative angle between the first object and the second object;
The control device, when there is an abnormality in the sensor, the pressure difference between the case side first port and the shaft side first port, and the case side second port and the shaft side second port Obtaining a relative angle between the first object and the second object based on the pressure difference between
The industrial machine according to claim 2. An excavator as an industrial machine according to claim 2 or 3,
A traveling body as the first object;
A revolving body as the second object;
A hydraulic motor as the hydraulic actuator for driving the traveling body,
Excavator.