Regulator for excavating hydraulic motors

Abstract

The regulator (2) includes a servo piston (4), a first switching valve (5), and a second switching valve (7). The servo piston (4) includes a small-diameter portion (41) and a large-diameter portion (42), with the annular surface of the large-diameter portion (42) facing the first pressure chamber (4a) and the end face of the large-diameter portion (42) facing the second pressure chamber (4b). The first switching valve (5) is connected to the input path (3) and the tank path (5a) supplying the inlet pressure to the hydraulic motor (9), and is connected to the second pressure chamber (4b) via the pressure regulating path (6). The second switching valve (7) is disposed between the first flow path (61) and the second flow path (62) of the pressure regulating path (6), and is connected to the detour path (75) branching off from the input path (3). The second switching valve (7) connects the first flow path (61) with the second flow path (62) or connects the detour path (75) with the second flow path (62).

Description

Technical Field

[0001] This disclosure relates to a regulator for a hydraulic motor used in excavation. Background Technology

[0002] Previously, excavators equipped with excavation units that dig longitudinal holes in the ground were known. These excavators were also called earth drills. The excavation unit includes a digging shaft extending vertically and a digging bucket located at the lower end of the digging shaft. For example, Japanese Patent Application Publication No. 2008-255765 discloses an excavation unit that uses a hydraulic motor as a rotary machine to rotate the digging shaft. Summary of the Invention

[0003] The hydraulic motor used in the excavation unit, i.e., the excavation hydraulic motor, is preferably a variable capacity type that can change its torque according to the excavation load. When the hydraulic motor is a variable capacity type, the capacity of the hydraulic motor is changed by a regulator.

[0004] For example, the regulator minimizes the capacity of the hydraulic motor and makes it rotate at low torque and high speed when the digging load is low, and maximizes the capacity of the hydraulic motor and makes it rotate at high torque and low speed when the digging load is high.

[0005] When excavating deep longitudinal holes in the foundation, the excavating unit's digging shaft is a telescopic structure. In such a long digging shaft, when the bucket encounters hard rock and cannot dig further, the shaft twists significantly. Therefore, when the operator reverses the rotation of the hydraulic motor to release the twist of the digging shaft, the hydraulic motor may over-rotate, potentially applying excessive stress to its structural components.

[0006] Therefore, the object of this disclosure is to provide a regulator for a digging hydraulic motor that can reduce excessive rotation of the hydraulic motor caused by the torsion of the digging shaft.

[0007] This disclosure provides a regulator for a digging hydraulic motor, which is a regulator for changing the capacity of the digging hydraulic motor. It includes: a servo piston comprising a small-diameter portion and a large-diameter portion, wherein an annular surface of the large-diameter portion on the small-diameter side faces a first pressure chamber, and an end face of the large-diameter portion opposite to the small-diameter side faces a second pressure chamber; the inlet pressure of the hydraulic motor is introduced into the first pressure chamber, and the piston moves in a direction that reduces the capacity of the hydraulic motor as the pressure introduced into the second pressure chamber increases; and a first switching valve connected to an input line and a tank line supplying the inlet pressure of the hydraulic motor, and connected to a pressure regulating line. The system is connected to the second pressure chamber and allows the pressure regulating path to communicate with either the input path or the tank path; and a second switching valve is disposed between a first flow path on the first switching valve side of the pressure regulating path and a second flow path on the second pressure chamber side, and is connected to a detour path branching off from the input path. When the capacity of the hydraulic motor is maintained at its maximum by the first switching valve, the first flow path is connected to the second flow path when the inlet pressure of the hydraulic motor is less than a set value, and the detour path is connected to the second flow path when the inlet pressure of the hydraulic motor is greater than the set value.

[0008] According to this disclosure, excessive rotation of the hydraulic motor caused by the release of the excavator shaft's torsion can be reduced. Attached Figure Description

[0009] Figure 1 This is a schematic structural diagram of the regulator of a hydraulic motor for excavation according to one embodiment;

[0010] Figure 2 middle, Figure 2 A is a side view of the excavator. Figure 2 B is an enlarged view of the mining unit;

[0011] Figure 3 This is a schematic structural diagram of the regulator in a modified example;

[0012] Figure 4 This is a schematic diagram of the regulator in another variation. Detailed Implementation

[0013] Figure 1 The regulator 2 of a hydraulic motor 9 for excavation according to one embodiment is shown. The hydraulic motor 9 is as follows... Figure 2 As shown in B, it is included in the excavation unit 15, and the excavation unit 15 is as follows: Figure 2 As shown in Figure A, it is mounted on excavator 1.

[0014] The excavator 1 includes a frame 11 extending vertically, on which a digging unit 15 is mounted. The digging unit 15 includes a base 16 coupled to the frame 11, a digging shaft 17 extending vertically through the base 16, and a bucket 18 located at the lower end of the digging shaft 17. The digging shaft 17 is rotatably supported on the base 16 and slidably supported vertically.

[0015] Furthermore, a reducer 19 is mounted on the base 16, and a hydraulic motor 9 is mounted on the reducer 19. The hydraulic motor 9 rotates the digging shaft 17 in the digging direction or the opposite direction of digging via the reducer 19.

[0016] The digging shaft 17 is a telescopic structure. The digging shaft 17 moves up and down and extends or retracts via a wire 13 through the winch unit 12 of the excavator 1. More specifically, the digging shaft 17 comprises multiple tubular bodies of varying diameters, with the nth tubular body from the outside at least partially fitted into the (n-1)th tubular body. The number of tubular bodies is shown as three in the illustration, but is not specifically limited.

[0017] like Figure 1 As shown, the hydraulic motor 9 has a pair of ports 91 and 92 that can be switched as an inlet port or an outlet port by rotating in the direction of rotation. Ports 91 and 92 are connected to feed and discharge lines 9a and 9b, respectively.

[0018] The hydraulic motor 9 is a variable capacity axial piston motor. The hydraulic motor 9 includes a rotating unit consisting of multiple pistons and a cylinder, and a housing that houses the rotating unit. In this embodiment, the hydraulic motor 9 is a swashplate motor with a swashplate 90.

[0019] The regulator 2 changes the capacity of the hydraulic motor 9. Specifically, the regulator 2 includes a servo piston 4 and a housing 20 that slidably holds the servo piston 4. In addition, the regulator 2 includes a first switching valve 5 and a second switching valve 7 assembled into the housing 20.

[0020] The housing 20 can be divided into parts for holding the servo piston 4, parts for assembling the first switching valve 5, and parts for assembling the second switching valve 7. Furthermore, the housing 20 can be integrated with the housing of the hydraulic motor 9.

[0021] The regulator 2 is supplied with the inlet pressure Pi of the hydraulic motor 9 via the input path 3. The input path 3 includes a pair of selector paths 31 and 32 connected to the supply and discharge paths 9a and 9b, and a supply path 33 that merges these selector paths 31 and 32. Check valves 35 and 36 are respectively provided on the selector paths 31 and 32. That is, the higher pressure of the supply and discharge paths 9a and 9b is the inlet pressure Pi, which is guided to the supply path 33 through the selector path 31 or 32 corresponding to the inlet pressure Pi.

[0022] The servo piston 4 includes a small diameter portion 41 and a large diameter portion 42. The annular surface of the large diameter portion 42 on the side of the small diameter portion 41 faces the first pressure chamber 4a, and the end face of the large diameter portion 42 on the opposite side of the small diameter portion 41 faces the second pressure chamber 4b.

[0023] As described above, in this embodiment, since the hydraulic motor 9 has a ramp 90, the servo piston 4 is connected to the ramp 90. When the servo piston 4 moves from the large diameter portion 42 to the small diameter portion 41, the capacity of the hydraulic motor 9 decreases; when the servo piston 4 moves from the small diameter portion 41 to the large diameter portion 42, the capacity of the hydraulic motor 9 increases. Hereinafter, the direction from the large diameter portion 42 to the small diameter portion 41 will be referred to as the "capacity reduction direction," and the direction from the small diameter portion 41 to the large diameter portion 42 will be referred to as the "capacity increase direction."

[0024] The first pressure chamber 4a is connected to the supply line 33 of the input line 3. That is, the inlet pressure Pi of the hydraulic motor 9 is introduced into the first pressure chamber 4a. The second pressure chamber 4b is connected to the first switching valve 5 through the pressure regulating line 6. The second switching valve 7 is disposed on the pressure regulating line 6.

[0025] As the pressure introduced into the second pressure chamber 4b increases, the servo piston 4 moves in the direction of decreasing capacity. When the pressure introduced into the second pressure chamber 4b exceeds a predetermined value corresponding to the area difference between the first pressure chamber 4a and the second pressure chamber 4b, the servo piston 4 moves in the direction of decreasing capacity until it abuts against the minimum side stopper, at which point the capacity of the hydraulic motor 9 becomes minimum. Conversely, when the pressure introduced into the second pressure chamber 4b is less than the predetermined value, the servo piston 4 moves in the direction of increasing capacity until it abuts against the maximum side stopper, at which point the capacity of the hydraulic motor 9 becomes maximum.

[0026] The aforementioned input path 3 also includes a branch path 34 that branches off from the supply path 33. Branch path 34 is connected to the first switching valve 5. The first switching valve 5 is also connected to the tank path 5a. The tank path 5a communicates with the space within the housing of the hydraulic motor 9 and with the tank via piping connecting the housing and the tank.

[0027] The first switching valve 5 connects the pressure regulating circuit 6 to either the branch circuit 34 or the tank circuit 5a. In this embodiment, the first switching valve 5 is capable of... Figure 1 The left position, i.e., the first position and Figure 1 The first switching valve 5 is a two-position valve that switches between the right-hand position and the second position. In this embodiment, the first position is a neutral position. The first switching valve 5 connects the pressure regulating path 6 to the tank path 5a in the first position and connects the branch path 34 to the pressure regulating path 6 in the second position. However, contrary to this embodiment, the second position can also be a neutral position. Furthermore, the first switching valve 5 can also be a three-position valve with a third position between the first and second positions that blocks all flow paths connected to the first switching valve 5.

[0028] More specifically, the first switching valve 5 includes a sleeve 52 slidably held by the housing 20 and a valve core 51 slidably held by the sleeve 52. The valve core 51 is connected to the servo piston 4 via a spring 46 and a feedback rod 45. That is, the position of the servo piston 4 is fed back to the valve core 51.

[0029] With this configuration, when the first switching valve 5 is in the second position, the pressure Ps introduced into the second pressure chamber 4b is regulated in a force-balanced manner acting on the large-diameter portion 42 of the servo piston 4 from both sides. In other words, when the first switching valve 5 is in the second position, the pressure regulating circuit 6 is connected to the branch circuit 34, thereby regulating the pressure Ps introduced into the second pressure chamber 4b. The regulated pressure Ps is less than the inlet pressure Pi of the hydraulic motor 9.

[0030] In this embodiment, the first switching valve 5 is driven by an electrical signal. The first switching valve 5 is electrically connected to the control device 21, which sends a command current to switch it from a first position to a second position. The control device 21 is also electrically connected to pressure sensors 22 and 23 located in the feed / discharge lines 9a and 9b. The higher pressure in the feed / discharge lines 9a and 9b is detected by pressure sensor 22 or 23 as the inlet pressure Pi.

[0031] Regarding control device 21, the functions of the elements disclosed in this specification can be executed using circuitry or processing circuitry, including general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), existing circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor, by including transistors or other circuitry, can be considered as processing circuitry or circuitry. In this disclosure, a circuit, unit, or device is hardware that performs the listed functions, or hardware programmed to perform the listed functions. The hardware can be the hardware disclosed in this specification, or it can be other known hardware programmed or configured to perform the listed functions. When the hardware is a processor identified as a type of circuit, the circuit, device, or unit is a combination of hardware and software, with the software used to construct the hardware and / or processor.

[0032] In this embodiment, when the inlet pressure Pi of the hydraulic motor 9, detected by pressure sensors 22 or 23, is less than the first set value α (a low load), the control device 21 sends a command current to the first switching valve 5 to switch the first switching valve 5 to the second position. This adjusts the pressure Ps introduced into the second pressure chamber 4b as described above. As a result, the hydraulic motor 9 rotates with a torque and speed corresponding to the inlet pressure Pi.

[0033] On the other hand, when the inlet pressure Pi of the hydraulic motor 9, detected by pressure sensor 22 or 23, exceeds the first set value α under high load, the control device 21 stops sending command current to the first switching valve 5. As a result, the first switching valve 5 returns to the first position, and the pressure regulating circuit 6 connects to the tank circuit 5a. Consequently, the pressure in the second pressure chamber 4b becomes almost zero, and the capacity of the hydraulic motor 9 reaches its maximum. Therefore, the hydraulic motor 9 rotates with high torque and low speed.

[0034] However, the first switching valve 5 does not necessarily need to be switched based on the inlet pressure Pi of the hydraulic motor 9. For example, a capacity selection switch for the operator to choose whether to fix it to the large capacity can be used. As long as the large capacity is not selected by the capacity selection switch, the control device 21 sends a command current to the first switching valve 5 to switch the first switching valve 5 to the second position. Furthermore, the first switching valve 5 can be driven by pilot pressure. That is, the first switching valve 5 has a pilot chamber for moving the valve core 51, and the electromagnetic proportional valve connected to the pilot chamber can be controlled by the control device 21.

[0035] The second switching valve 7 is disposed between the first flow path 61 on the side of the first switching valve 5 in the pressure regulating circuit 6 and the second flow path 62 on the side of the second pressure chamber 4b. The second switching valve 7 is connected to the bypass loop 75 branching off from the supply circuit 33.

[0036] The second switching valve 7 functions as a safety valve under high load conditions, that is, when the capacity of the hydraulic motor 9 is maintained at its maximum through the first switching valve 5. The second switching valve 7 is capable of... Figure 1 The left position, i.e., the first position and Figure 1 The right-hand position is a two-position valve that switches between the first and second positions. In this embodiment, the first position is a neutral position. The second switching valve 7 connects the first flow path 61 and the second flow path 62 in the first position, and connects the detour loop 75 and the second flow path 62 in the second position.

[0037] In this embodiment, the second switching valve 7 is driven by pilot pressure. The second switching valve 7 includes a valve core 71 slidably held by the housing 20. Furthermore, the second switching valve 7 includes a first pilot chamber 72 for moving the valve core 71 in a direction of switching from a second position to a first position, and a second pilot chamber 73 for moving the valve core 71 in a direction of switching from a first position to a second position.

[0038] The first pilot chamber 72 is connected to the first pilot flow path 81, which branches off from the first flow path 61 of the pressure regulating path 6. Therefore, when the first switching valve 5 is in the second position under low load, the pressure Ps regulated by the first switching valve 5 is introduced into the first pilot chamber 72, and when the first switching valve 5 is in the first position under high load, the pressure in the first pilot chamber 72 becomes almost zero.

[0039] The second pilot chamber 73 is connected to the second pilot flow path 82, which branches off from the detour path 75. The second pilot flow path 82 can also branch off from the supply path 33 or the branch path 34 of the input path 3. Therefore, the inlet pressure Pi of the hydraulic motor 9 is introduced into the second pilot chamber 73. The second pilot flow path 82 is provided with a throttling section 83.

[0040] When the pressure in the second pilot chamber 73 is greater than the pressure in the first pilot chamber 72 plus the value of the second set value β, the second switching valve 7 switches from the first position to the second position. The second set value β is greater than the value of the first set value α used to determine whether it is a low load or a high load. Furthermore, the second set value β is set to be greater than the maximum inlet pressure Pm of the hydraulic motor 9 expected during the rotation of the bucket 18, i.e., during digging.

[0041] The hydraulic circuit including the hydraulic motor 9 includes a relief valve. The first setting value α is 70% to 90% of the relief valve's relief pressure, and the second setting value β is the value between the first setting value α and the relief pressure. For example, if the relief valve's relief pressure is 34 MPa, the first setting value is 30 MPa, and the second setting value is 31 to 33 MPa.

[0042] At low load, i.e., when Pi < α, as described above, the pressure Ps introduced into the second pressure chamber 4b is adjusted by the first switching valve 5. Therefore, the pressure difference between the inlet pressure Pi of the hydraulic motor 9 introduced into the second pilot chamber 73 and the pressure Ps introduced into the first pilot chamber 72 will not exceed the second set value β. Therefore, the second switching valve 7 is maintained in the first position.

[0043] On the other hand, under high load, i.e. when Pi > α, the pressure in the first pilot chamber 72 becomes almost zero. However, as mentioned above, the second set value β is set to be greater than the maximum inlet pressure Pm of the hydraulic motor 9 expected during excavation. Therefore, during the rotation of the bucket 18, the second switching valve 7 remains in the first position.

[0044] When the bucket 18 encounters a hard rock surface and cannot dig, the inlet pressure Pi of the hydraulic motor 9 rises further beyond the second set value β. Then, the second switching valve 7 switches from the first position to the second position, and the detour circuit 75 connects to the second flow path 62 of the pressure regulating circuit 6. As a result, the inlet pressure Pi of the hydraulic motor 9 is introduced into the second pressure chamber 4b, and the capacity of the hydraulic motor 9 becomes minimal, reducing the torque of the hydraulic motor 9. Consequently, even if the digging shaft 17 twists significantly before the inlet pressure Pi of the hydraulic motor 9 exceeds the second set value β, the twisting of the digging shaft 17 can be offset to a degree corresponding to the reduction in the torque of the hydraulic motor 9. Therefore, the rotational speed of the hydraulic motor 9 during reverse rotation can be reduced compared to when the digging shaft 17 twists significantly.

[0045] That is, in order to eliminate the state in which the operator cannot dig, even if a command is sent to the hydraulic motor 9 to rotate in the opposite direction, the hydraulic motor 9 can be rotated in the opposite direction in a state in which the torsion of the digging shaft 17 is counteracted and the torque is reduced to a corresponding degree. Therefore, the excessive rotation of the hydraulic motor 9 caused by the release of the torsion of the digging shaft 17 can be reduced.

[0046] Furthermore, in this embodiment, a throttling section 83 is provided on the second pilot flow path 82, thereby suppressing the switching of the second switching valve 7 due to the sudden change in the surge pressure of the hydraulic motor 9, i.e., the inlet pressure Pi.

[0047] (Modified example)

[0048] This disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the essence of this disclosure.

[0049] For example, the second switching valve 7 does not necessarily need to be driven by pilot pressure; it can also be driven by an electrical signal. However, if the structure is as described in the embodiment, the second switching valve 7 can be switched automatically.

[0050] Alternatively, it can be like Figure 3 In the modified example of regulator 2A shown, two throttling sections 63 and 64 are provided on the first flow path 61 of the pressure regulating path 6. At this time, a bypass loop 65 is provided to bypass one of the throttling sections 63 or 64. On this bypass loop 65, a check valve 66 may also be provided to allow flow from the second switching valve 7 toward the first switching valve 5 but to prevent its reverse flow.

[0051] Various structures can also be used for the first switching valve 5. For example, such as Figure 3 As shown, the second position is a neutral position, and the first switching valve 5 may include a piston 53 that presses the valve core 51 in the direction of switching from the second position to the first position. Figure 3 In the example shown, the first switching valve 5 includes two pilot chambers 54 and 55 for actuating the piston 53. One pilot chamber 54 is connected to the supply line 33 via a pilot flow path 5b, and the other pilot chamber 55 receives a signal pressure via a pilot flow path 5c. For example, the signal pressure is normally zero, but becomes high pressure when the operator wants to maintain a large capacity.

[0052] again, Figure 3 In the example shown, the feedback rod 45 is connected to the sleeve 52, and the position of the servo piston 4 is fed back to the sleeve 52.

[0053] Or, such as Figure 4 In the modified example shown, the position of the servo piston 4 can be not fed back to the first switching valve 5. Figure 4In the example shown, the first switching valve 5 includes a pilot chamber 56 for moving the valve core 51 in a direction of switching from the second position to the first position. The pilot chamber 56 is connected to the supply passage 33 via a pilot flow path 5d.

[0054] (Summarize)

[0055] This disclosure provides a regulator for a digging hydraulic motor, which is a regulator for changing the capacity of the digging hydraulic motor. It includes: a servo piston comprising a small-diameter portion and a large-diameter portion, wherein an annular surface of the large-diameter portion on the small-diameter side faces a first pressure chamber, and an end face of the large-diameter portion opposite to the small-diameter side faces a second pressure chamber; the inlet pressure of the hydraulic motor is introduced into the first pressure chamber, and the piston moves in a direction that reduces the capacity of the hydraulic motor as the pressure introduced into the second pressure chamber increases; and a first switching valve connected to an input line and a tank line supplying the inlet pressure of the hydraulic motor, and connected to a pressure regulating line. The system is connected to the second pressure chamber and allows the pressure regulating path to communicate with either the input path or the tank path; and a second switching valve is disposed between a first flow path on the first switching valve side of the pressure regulating path and a second flow path on the second pressure chamber side, and is connected to a detour path branching off from the input path. When the capacity of the hydraulic motor is maintained at its maximum by the first switching valve, the first flow path is connected to the second flow path when the inlet pressure of the hydraulic motor is less than a set value, and the detour path is connected to the second flow path when the inlet pressure of the hydraulic motor is greater than the set value.

[0056] According to the above structure, under high load conditions where the inlet pressure of the hydraulic motor exceeds the first set value, the first switching valve connects the pressure regulating circuit to the tank circuit, so the pressure in the second pressure chamber becomes almost zero and the capacity of the hydraulic motor becomes maximum. Therefore, the hydraulic motor rotates with high torque and low speed. In this state, when the bucket contacts a harder rock surface and cannot dig, the inlet pressure of the hydraulic motor rises further, exceeding the second set value. At this point, the second switching valve connects the detour circuit to the second flow path of the pressure regulating circuit. Thus, the inlet pressure of the hydraulic motor is introduced into the second pressure chamber, and the capacity of the hydraulic motor becomes minimum, reducing the torque of the hydraulic motor. As a result, even if the digging shaft twists significantly before the inlet pressure of the hydraulic motor exceeds the second set value, the twist can be offset to a degree corresponding to the reduction in the torque of the hydraulic motor. Therefore, excessive rotation of the hydraulic motor caused by the release of the digging shaft's twist can be reduced.

[0057] Alternatively, the second switching valve can switch between a first position connecting the first flow path and the second flow path and a second position connecting the detour path and the second flow path. The second switching valve includes: a valve core; a first pilot chamber for moving the valve core in a direction from the second position to the first position; and a second pilot chamber for moving the valve core in a direction from the first position to the second position. A first pilot flow path branching from the first flow path of the pressure regulating path is connected to the first pilot chamber, and a second pilot flow path branching from the detour path or the input path is connected to the second pilot chamber. According to this structure, the second switching valve can be switched automatically.

[0058] Alternatively, a throttling section may be provided in the second pilot flow path. With this structure, the switching of the second switching valve can be suppressed due to rapid changes in the inlet pressure caused by the impact pressure of the hydraulic motor.

[0059] For example, the hydraulic motor may include a ramp, and the servo piston may be connected to the ramp.

Claims

1. A regulator of a hydraulic excavator, characterized by comprising: a servo piston including a small-diameter portion and a large-diameter portion, an annular surface of the small-diameter portion of the large-diameter portion facing a first pressure-receiving chamber, an end surface of the large-diameter portion opposite to the small-diameter portion facing a second pressure-receiving chamber, and an inlet pressure of a hydraulic motor being introduced into the first pressure-receiving chamber and moving in a direction in which a capacity of the hydraulic motor is reduced as a pressure introduced into the second pressure-receiving chamber becomes higher; a first switching valve connected to an input passage for the inlet pressure of the hydraulic motor and a tank passage, connected to the second pressure-receiving chamber through a pressure regulating passage, and making the pressure regulating passage communicate with either one of the input passage and the tank passage; and a second switching valve interposed between a first flow passage of the first switching valve side of the pressure regulating passage and a second flow passage of the second pressure-receiving chamber side, connected to a detour passage branched from the input passage, and making the first flow passage communicate with the second flow passage when the inlet pressure of the hydraulic motor is less than a set value and making the detour passage communicate with the second flow passage when the inlet pressure of the hydraulic motor is greater than the set value in a state where the capacity of the hydraulic motor is maintained at a maximum by the first switching valve.

2. The regulator of a hydraulic excavator according to claim 1, characterized in that the second switching valve switches between a first position in which the first flow passage communicates with the second flow passage and a second position in which the detour passage communicates with the second flow passage; the second switching valve includes a spool, a first pilot chamber for moving the spool in a direction in which the spool switches from the second position to the first position, and a second pilot chamber for moving the spool in a direction in which the spool switches from the first position to the second position; and a first pilot flow passage branched from the first flow passage of the pressure regulating passage is connected to the first pilot chamber, and a second pilot flow passage branched from the detour passage or the input passage is connected to the second pilot chamber.

3. The regulator of a hydraulic excavator according to claim 2, characterized in that a throttle portion is provided in the second pilot flow passage.

4. The regulator of a hydraulic excavator according to any one of claims 1 to 3, characterized in that the hydraulic motor includes a swash plate; and the servo piston is linked to the swash plate. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Images