Hydraulic valve device

Abstract

The purpose of the present invention is to efficiently regenerate oil discharged from a rod chamber, while suppressing an increase in size and not impairing the operating speed of a hydraulic cylinder for an arm. A valve body 31 is provided with a first spool hole 34 for accommodating a first spool 32 and a second spool hole 35 for accommodating a second spool 33. The second spool hole 35 is provided with a regeneration port 35d. A regeneration oil passage 45 for allowing oil to pass from the regeneration port 35d to a bottom oil passage 41 is provided between the regeneration port 35d and the bottom oil passage 41. When oil is discharged from a rod chamber 11a, a second meter-out port 35c is connected to the regeneration port 35d. When the pressure in the rod chamber 11a becomes equal to or less than the pressure in the bottom chamber 11b, the second meter-out port 35c is connected to a second tank port 35e.

Description

Hydraulic Valve Device

[0001] The present invention relates to a hydraulic valve device that controls the supply of oil to a rod chamber and a bottom chamber of an arm hydraulic cylinder, thereby moving the arm of a work machine in an excavation direction and a dump direction.

[0002] In this type of hydraulic valve device, when the operating rod of the arm hydraulic cylinder is advanced (excavation), the oil discharged from the rod chamber is recycled and supplied to the bottom chamber. To recycle the oil in the bottom chamber, it is preferable to reduce the amount of oil sent to the tank. However, simply narrowing the flow path from the bottom chamber to the tank can result in a situation where the advancing movement of the operating rod cannot be accelerated without regenerating the oil. For this reason, a conventional system has been proposed that solves the above problem by narrowing the oil path when regenerating the oil and providing an oil passage with an unloading valve between the rod chamber and the tank (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2019-2531

[0004] However, when an oil passage having an unloading valve is provided, there is a concern that the number of parts increases and the hydraulic valve device becomes larger.

[0005] In view of the above circumstances, an object of the present invention is to provide a hydraulic valve device that can efficiently regenerate oil discharged from a rod chamber without increasing in size and without impairing the operating speed of an arm hydraulic cylinder.

[0006] In order to achieve the above object, the hydraulic valve device according to the present invention is a hydraulic valve device that operates an arm of a work machine in an excavation direction and a dump direction by supplying oil from a hydraulic pump to a bottom chamber and a rod chamber of a hydraulic cylinder for an arm, and the valve body is provided with a first spool that controls the supply of oil to the bottom chamber and a second spool that controls the supply of oil to the rod chamber, and a first spool hole that houses the first spool is provided with a first pump oil supply port connected to the hydraulic pump, a first meter-in port and a first meter-out port that are connected to the bottom chamber through a bottom oil passage, and a first tank port that is connected to a tank, and a second spool hole that houses the second spool is provided with The hydraulic oil supply system includes a second pump oil supply port connected to a hydraulic pump, second meter-in and second meter-out ports connected to the rod chamber through a rod oil passage, and a second tank port connected to a tank, a regeneration port is provided in the second spool hole, and a regeneration oil passage is provided between the regeneration port and the bottom oil passage to allow oil to pass from the regeneration port to the bottom oil passage, the second meter-out port is connected to the regeneration port when oil is discharged from the rod chamber, and the second meter-out port is connected to the second tank port when oil cannot pass from the regeneration port to the bottom oil passage depending on the pressure in the rod chamber and the pressure in the bottom chamber.

[0007] According to the present invention, when oil can be recycled, oil discharged from the rod chamber is supplied to the bottom chamber through the recycling port and recycled oil passage, while when oil recycling is not possible, the spool moves and the oil discharged from the rod chamber is sent to the tank through the second meter-out port. Therefore, it is possible to efficiently recycle oil while preventing the operating speed of the arm hydraulic cylinder from slowing down without requiring additional parts such as an unloading valve.

[0008] FIG. 1 is a cross-sectional view showing a hydraulic drive circuit to which a hydraulic valve device according to an embodiment of the present invention is applied, with the spool positioned in a neutral position. FIG. 2 is a diagram showing the hydraulic drive circuit shown in FIG. 1. FIG. 3 is a side view of a work machine equipped with a hydraulic cylinder controlled by the hydraulic drive circuit shown in FIG. 1. FIG. 4 is a cross-sectional view showing a state in which the spool is positioned at an intermediate position in the excavation direction in the hydraulic drive circuit shown in FIG. 1. FIG. 5 is a diagram showing the hydraulic drive circuit shown in FIG. 4. FIG. 6 is a cross-sectional view showing a state in which the spool is positioned at a full stroke position in the excavation direction in the hydraulic drive circuit shown in FIG. 1. FIG. 7 is a diagram showing the hydraulic drive circuit shown in FIG. 6. FIG. 8 is a graph showing the relationship between the stroke amount and the opening area of ​​the meter-out oil passage when the spool moves in the excavation direction in the hydraulic valve device shown in FIG. 1. FIG. 9 is a cross-sectional view showing a state in which the spool moves in the dump direction in the hydraulic drive circuit shown in FIG. 1. FIG. 10 is a diagram showing the hydraulic drive circuit shown in FIG. 9.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a hydraulic valve device according to the present invention will be described in detail below with reference to the accompanying drawings.

[0010] 1 and 2 show a hydraulic drive circuit to which a hydraulic valve device according to an embodiment of the present invention is applied. The illustrated hydraulic drive circuit operates an arm hydraulic cylinder 10 using oil from a hydraulic pump 1. The hydraulic pump 1 is a variable-displacement pump driven by an engine 2, and its displacement is changed by changing the tilt angle of the swash plate or inclined axis. As shown in FIG. 3 , the arm hydraulic cylinder 10 is a single-rod, double-acting type for operating an arm AM provided on a work machine relative to a boom BM. The arm AM is rotatably supported at its base end on the tip of the boom BM by an arm shaft S extending horizontally. When the arm hydraulic cylinder 10 is operated to advance the actuating rod 12 relative to the cylinder body 11, the arm AM moves in a direction that draws the arm AM toward the upper rotating structure JS (excavation direction). On the other hand, when the arm hydraulic cylinder 10 is operated to retract the actuating rod 12 relative to the cylinder body 11, the arm AM moves in a direction that moves the arm AM away from the upper rotating structure JS (dumping direction).

[0011] 1 and 2, the hydraulic drive circuit is provided with a hydraulic valve device between the hydraulic pump 1 and the arm hydraulic cylinder 10. The hydraulic valve device has an arm direction switching valve that selectively connects the hydraulic pump 1 to the rod chamber 11a and the bottom chamber 11b of the arm hydraulic cylinder 10, and is equipped with two spools 32, 33 and a controller 100 in a valve body 31.

[0012] The spools 32, 33 are cylindrical and each have a plurality of lands divided by annular grooves, and are disposed in separate spool holes 34, 35 formed in the valve body 31 with their axes parallel to each other and movable along their respective axes. For convenience, the spool located on the left in Figure 2 will be referred to as the first spool 32, and the spool located on the right in Figure 2 will be referred to as the second spool 33 below.

[0013] The first spool bore 34, which accommodates the first spool 32, is provided with a first pump oil supply port 34a, a first meter in port 34b, a first meter-out port 34c, and a first tank port 34d, in this order from the end located at the bottom in Fig. 1. When the first spool 32 moves along the axial direction, the connection states of the first pump oil supply port 34a and the first tank port 34d to the first meter in port 34b and the first meter-out port 34c are switched. More specifically, as shown in Figs. 1 and 2, when the first spool 32 is positioned in the neutral position, the first meter in port 34b and the first meter-out port 34c are both disconnected from the first pump oil supply port 34a and the first tank port 34d. 1 (to the right in FIG. 2) from the neutral position, the first meter port 34b is connected to the first pump oil supply port 34a, while the first meter-out port 34c and the first tank port 34d remain blocked, as shown in FIG. 4 and FIG. 5. When the first spool 32 is moved from the neutral position upward in FIG. 1 (to the left in FIG. 2), the first meter port 34b remains blocked, while the first meter-out port 34c and the first tank port 34d are connected, as shown in FIG. 9 and FIG. 10.

[0014] The first meter-in port 34b and the first meter-out port 34c are each connected to the bottom chamber 11b of the arm hydraulic cylinder 10 through a bottom oil passage 41. The first pump oil supply port 34a is connected to the hydraulic pump 1 through an oil supply passage 42, and the first tank port 34d is connected to the tank T through an oil drain passage 43. A first pressure sensor P1 is provided in the bottom oil passage 41 to detect the pressure in the bottom chamber 11b.

[0015] The second spool hole 35 is provided with a second pump oil supply port 35a, a second meter port 35b, a second meter-out port 35c, a regeneration port 35d, and a second tank port 35e, in this order from the end located at the bottom in Fig. 1. When the second spool 33 moves along the axial direction, the connection states of the second pump oil supply port 35a, the regeneration port 35d, and the second tank port 35e to the second meter port 35b and the second meter-out port 35c are switched. More specifically, when the second spool 33 is positioned in the neutral position, as shown in Figs. 1 and 2, the second meter port 35b and the second meter-out port 35c are all disconnected from the second pump oil supply port 35a, the regeneration port 35d, and the second tank port 35e. 1 (to the right in FIG. 2) from the neutral position to the intermediate position (half-stroke position), the second meter-out port 35c is connected to the regeneration port 35d, while the second tank port 35e, the second meter port 35b, and the second pump oil supply port 35a remain blocked, as shown in FIG. 4 and FIG. 5. When the second spool 33 further moves in the same direction and reaches the full-stroke position, the second meter-out port 35c is connected to the regeneration port 35d and the second tank port 35e, while the second meter port 35b and the second pump oil supply port 35a remain blocked, as shown in FIG. 6 and FIG. 7. When the second spool 33 moves from the neutral position upward in FIG. 1 (leftward in FIG. 2), as shown in FIGS. 9 and 10, the second meter-out port 35c remains blocked, the second meter port 35b and the second pump oil supply port 35a are connected, and the regeneration port 35d is connected to the second tank port 35e.

[0016] The second meter port 35b and the second meter-out port 35c are each connected to the rod chamber 11a of the arm hydraulic cylinder 10 through a rod oil passage 44. The regeneration port 35d of the second spool hole 35 is connected to the bottom oil passage 41 through a regeneration oil passage 45. A pilot check valve 46 is provided in the regeneration oil passage 45, which functions to allow oil to pass only from the regeneration port 35d to the bottom oil passage 41 when pilot pressure is not supplied. This pilot check valve 46 allows oil to pass from the bottom oil passage 41 to the regeneration port 35d when pilot pressure is supplied. A second pressure sensor P2 that detects the pressure in the rod chamber 11a is provided in the rod oil passage 44.

[0017] The two spools 32, 33 are each provided with a neutral spring 47, and pressure chambers 32A, 32B, 33A, 33B are provided at both ends of each spool. The neutral springs 47 are used to maintain the spools 32, 33 in their neutral positions. The pressure chambers 32A, 32B accommodate the ends of the first spool 32 and are filled with oil. The pressure chambers 33A, 33B accommodate the ends of the second spool 33 and are filled with oil. Pilot oil passages 51A, 51B are connected to the pressure chambers 32A, 32B, respectively, for applying pilot pressures output from the operating valves 50A, 50B. Pilot oil passages 53A, 53B are connected to the pressure chambers 33A, 33B, respectively, for applying pilot pressures output from the operating valves 52A, 52B. The control valves 50A, 50B are operated by control signals output from a controller 100 (described later) in response to operation of a control lever (electric lever) 54. When pilot pressures output from the control valves 50A, 50B are applied selectively to the pressure chambers 32A, 32B through pilot oil passages 51A, 51B, the first spool 32 can be moved against the spring force of the neutral spring 47. When the pilot pressures applied to the pressure chambers 32A, 32B are removed, the first spool 32 returns to the neutral position due to the spring force of the neutral spring 47. Similarly, when pilot pressures output from the control valves 52A, 52B are applied selectively to the pressure chambers 33A, 33B through pilot oil passages 53A, 53B, the second spool 33 can be moved against the spring force of the neutral spring 47. When the pilot pressure applied to the pressure chambers 33A and 33B is removed, the second spool 33 returns to the neutral position due to the spring force of the neutral spring 47. In this embodiment, a branch pilot oil line 55 that applies pilot pressure to the above-mentioned pilot check valve 46 is connected to a pilot oil line 53B that is connected to the pressure chamber 33B provided to the right of the second spool 33 in the drawing.

[0018] The controller 100 outputs control signals to the operating valves 50A, 50B, 52A, and 52B in accordance with the operating state of the operating lever 54 and the pressure state of the arm hydraulic cylinder 10 output from the two pressure sensors P1 and P2.

[0019] If the operating lever 54 is now in the neutral position, the controller 100 outputs a control signal to each of the operating valves 50A, 50B, 52A, and 52B so as not to supply pilot pressure. As a result, the two spools 32 and 33 are each placed in their neutral positions, no oil flows through the rod chamber 11a and the bottom chamber 11b of the arm hydraulic cylinder 10, and the operating rod 12 maintains its current position relative to the cylinder body 11.

[0020] When the control lever 54 is operated in the excavation direction from this state, the controller 100 outputs control signals to the control valves 50A, 50B, 52A, and 52B so that the first spool 32 and the second spool 33 move to the right in Fig. 2 (downward in Fig. 1), respectively. That is, the controller 100 supplies pilot pressure to the pressure chamber 32A located to the left of the first spool 32 in Fig. 2 (the pressure chamber 32A located above in Fig. 1) and the pressure chamber 33A located to the left of the second spool 33 (the pressure chamber 33A located above in Fig. 1), thereby moving the first spool 32 and the second spool 33 to the right in Fig. 2. At this time, the controller 100 refers to the output results of the first pressure sensor P1 and the second pressure sensor P2 and controls the position of the second spool 33 in accordance with the graph shown in Fig. 8. When the pressure detected by the second pressure sensor P2 exceeds the pressure detected by the first pressure sensor P1, such as when the arm AM and bucket of the work machine are being operated in the air, the controller 100 outputs a control signal to the operating valves 52A, 52B so that the second spool 33 stops at the intermediate position described above.

[0021] When the first spool 32 moves to the right and the second spool 33 moves to the intermediate position, as shown in Figures 4 and 5, oil from the hydraulic pump 1 is supplied to the bottom chamber 11b of the arm hydraulic cylinder 10 through the oil feed passage 42, the first pump oil supply port 34a, the first meter port 34b, and the bottom oil passage 41. At the same time, the entire amount of oil discharged from the rod chamber 11a is supplied to the bottom oil passage 41 through the rod oil passage 44, the second meter-out port 35c, the regeneration port 35d, and the regeneration oil passage 45. In other words, the entire amount of oil discharged from the rod chamber 11a is supplied to the bottom chamber 11b together with oil from the hydraulic pump 1 (oil regeneration). This allows the operating rod 12 of the arm hydraulic cylinder 10 to move forward and backward quickly, which has various advantages, such as enabling the work machine to perform excavation work efficiently and improving fuel efficiency.

[0022] During the above-described operation, when the pressure detected by the second pressure sensor P2 becomes equal to or lower than the pressure detected by the first pressure sensor P1, the controller 100 outputs a control signal to the operating valves 52A, 52B to move the second spool 33 to the full-stroke position. In this state, oil from the hydraulic pump 1 is supplied to the bottom chamber 11b of the arm hydraulic cylinder 10 through the oil feed passage 42, the first pump oil supply port 34a, the first meter port 34b, and the bottom oil passage 41. At the same time, oil discharged from the rod chamber 11a is sent to the tank T through the rod oil passage 44, the second meter-out port 35c, the second tank port 35e, and the drain oil passage 43. In other words, under conditions where oil regeneration is not possible, the oil discharged from the rod chamber 11a is returned to the tank T without being throttled, eliminating the risk of impairing the operating speed of the operating rod 12. This allows the arm hydraulic cylinder 10 to be operated continuously and quickly, which has the advantage of enabling, for example, excavation work to be carried out efficiently by a work machine. Moreover, because the oil in the bottom chamber 11b can be returned to the tank T simply by moving the second spool 33 from the intermediate position to the full stroke position, no additional parts such as an unloading valve are required. Therefore, there is no concern that the number of parts will increase or that the hydraulic valve device will become larger.

[0023] On the other hand, when the control lever 54 is operated in the dump direction from the neutral position, the controller 100 outputs control signals to the control valves 50A, 50B, 52A, and 52B so that the first spool 32 and the second spool 33 move leftward in Fig. 2. That is, the controller 100 supplies pilot pressure to the pressure chamber 32B located to the right of the first spool 32 in Fig. 2 (the pressure chamber 32B located below in Fig. 1) and the pressure chamber 33B located to the right of the second spool 33 (the pressure chamber 33B located below in Fig. 1), thereby moving the first spool 32 and the second spool 33 leftward in Fig. 2.

[0024] When the first spool 32 and the second spool 33 each move leftward, as shown in Figures 9 and 10, oil from the hydraulic pump 1 is supplied to the rod chamber 11a of the arm hydraulic cylinder 10 through the oil supply passage 42, the second pump oil supply port 35a, the second meter port 35b, and the rod oil passage 44. At the same time, oil discharged from the bottom chamber 11b is sent to the tank T through the rod oil passage 44, the first meter-out port 34c, and the first tank port 34d. In addition, when pilot pressure is output from the operating valve 52B to the pressure chamber 33B located to the right of the second spool 33, the pilot check valve 46 provided in the regeneration oil passage 45 is allowed to pass oil from the bottom oil passage 41 to the regeneration port 35d. As a result, oil from the bottom oil passage 41 is also sent to the tank T through the regeneration oil passage 45, the regeneration port 35d, the second tank port 35e, and the drain oil passage 43. Therefore, the operating rod 12 of the arm hydraulic cylinder 10 can be quickly retracted, which has the advantage of enabling, for example, efficient dumping of the work machine. Moreover, since the oil in the bottom chamber 11b can be returned to the tank T using the regeneration port 35d and regeneration oil passage 45 described above, there is no need to provide dedicated parts or oil passages separately. Therefore, there is no concern about an increase in the number of parts or an increase in the size of the hydraulic valve device.

[0025] In the above-described embodiment, when the arm hydraulic cylinder is operated in the dump direction, the oil in the bottom chamber is also sent to the tank through the regeneration oil passage, but this is not necessarily limited to this. In this case, it is sufficient to provide a check valve in the regeneration oil passage that only allows oil to pass from the regeneration port to the bottom oil passage.

[0026] Furthermore, in the above-described embodiment, when the first meter port is connected to the first pump oil supply port under conditions in which the pressure in the rod chamber is greater than the pressure in the bottom chamber, the entire amount of oil in the rod chamber is supplied to the bottom chamber, but the present invention is not limited to this.

[0027] Furthermore, in the above-described embodiment, when the first meter port is connected to the first pump oil supply port, whether oil regeneration is possible is determined based on the pressure in the rod chamber and the pressure in the bottom chamber. However, the present invention is not limited to this. For example, with respect to the arm hydraulic cylinder 10, the first spool 32 may be positioned in the neutral position, and only the second spool 33 may be moved to the right in FIG. 1 . As shown in FIGS. 5 and 7 , the regeneration port 35d may be connected to the second meter-out port 35c. In this case, oil is not supplied from the hydraulic pump 1 to the arm hydraulic cylinder 10, but oil discharged from the rod chamber 11a is supplied to the bottom chamber 11b through the regeneration oil passage 45. Therefore, in the work machine, the operating rod 12 advances relative to the cylinder body 11 of the arm hydraulic cylinder 10, allowing the arm AM to perform an excavation operation.

[0028] REFERENCE SIGNS LIST 1 Hydraulic pump 10 Arm hydraulic cylinder 11a Rod chamber 11b Bottom chamber 31 Valve body 32 First spool 33 Second spool 34 First spool hole 34a First pump oil supply port 34b First meter in port 34c First meter out port 34d First tank port 35 Second spool hole 35a Second pump oil supply port 35b Second meter in port 35c Second meter out port 35d Regeneration port 35e Second tank port 41 Bottom oil passage 44 Rod oil passage 45 Regeneration oil passage 46 Pilot check valve AM Arm P1, P2 Pressure sensor T Tank

Claims

1. A hydraulic valve device which operates the arm of a work machine in an excavation direction and a dump direction by supplying oil from a hydraulic pump to a bottom chamber and a rod chamber of a hydraulic cylinder for an arm, wherein a valve body is provided with a first spool which controls the supply of oil to the bottom chamber and a second spool which controls the supply of oil to the rod chamber, a first spool hole which houses the first spool is provided with a first pump oil supply port connected to the hydraulic pump, a first meter in port and a first meter out port which are connected to the bottom chamber through a bottom oil passage, and a first tank port which is connected to a tank, a second spool hole which houses the second spool is provided with a second pump oil supply port which is connected to the hydraulic pump, a second meter in port and a second meter out port which are connected to the rod chamber through a rod oil passage, and a second tank port which is connected to a tank, a regeneration port is provided in the second spool hole, and a regeneration oil passage is provided between the regeneration port and the bottom oil passage which allows oil to pass from the regeneration port to the bottom oil passage, a second meter-out port connected to the regeneration port when oil is discharged from the rod chamber, and a second meter-out port connected to the second tank port when oil cannot pass from the regeneration port to the bottom oil passage depending on the pressure of the rod chamber and the pressure of the bottom chamber.

2. A hydraulic valve device as described in claim 1, characterized in that the regeneration oil passage is provided with a check valve which only allows oil to pass from the regeneration port to the bottom oil passage on the condition that the pressure in the rod chamber is greater than the pressure in the bottom chamber.

3. A hydraulic valve device as described in claim 1, characterized in that when oil is discharged from the rod chamber, if the pressure in the rod chamber is greater than the pressure in the bottom chamber, communication between the second meter-out port and the second tank port is blocked.

4. The hydraulic valve device as described in claim 1, characterized in that when the second meter-out port is connected to the second pump oil supply port, the regeneration port is connected to the second tank port, and the regeneration oil passage is provided with a check valve that only allows oil to pass from the regeneration port to the bottom oil passage under normal conditions, but allows oil to pass from the bottom oil passage to the regeneration port only when the first meter-out port is connected to the first tank port and the second meter-out port is connected to the second pump oil supply port.

5. The hydraulic valve device as described in claim 1, characterized in that the second tank port and the regeneration port are arranged side by side in the second spool hole, and when the second spool moves from a neutral position in the excavation direction, the second meter-out port is connected to the regeneration port with communication between the second meter-out port and the second tank port being cut off, and when the second spool moves further in the same direction, the second meter-out port is connected to the second tank port.

6. The hydraulic valve device according to claim 1, further comprising a sensor for detecting the pressure in said rod chamber and a sensor for detecting the pressure in said bottom chamber.