Hydraulic device

Abstract

To control the extrusion speed of the rod of a hydraulic cylinder without complicating the maintenance work of a hydraulic device in the hydraulic device for driving the hydraulic cylinder.SOLUTION: The driving hydraulic oil discharged from the rod chamber (105) of the hydraulic cylinder (100) flows through the rod-side passage (22) of the hydraulic apparatus (10). The control valve (40) of the hydraulic apparatus (10) operates in accordance with the pressure of the controlling hydraulic oil supplied by the pump (61), and controls the flow of the driving hydraulic oil in the rod-side passage (22). The controller (70) of the hydraulic apparatus (10) controls the pressure of the hydraulic oil for control supplied to the control valve (40) by the pump (61).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to hydraulic systems. [Background technology]

[0002] Patent Document 1 discloses a hydraulic device that drives a die-casting machine. In the die-casting machine, a plunger that pushes out molten metal is driven by a hydraulic cylinder. The hydraulic device drives the hydraulic cylinder of the die-casting machine. In this hydraulic device, a servo valve is provided in a pipe connected to the rod chamber of the hydraulic cylinder.

[0003] The hydraulic device disclosed in Patent Document 1 controls the extrusion speed of the rod of a hydraulic cylinder by meter-out control. Specifically, with a servo valve closed, hydraulic oil is supplied to the head chamber of the hydraulic cylinder. When the pressure in the head chamber reaches a predetermined value, the servo valve opens. When the servo valve opens, hydraulic oil is discharged from the rod chamber of the hydraulic cylinder, pushing the rod out. At that time, the extrusion speed of the rod is controlled by adjusting the opening of the servo valve and adjusting the flow rate of hydraulic oil flowing out of the rod chamber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-142245 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the hydraulic device disclosed in Patent Document 1, the extrusion speed of the hydraulic cylinder rod can be precisely controlled by controlling the opening of the servo valve. However, because the servo valve controls the position of the spool in very fine steps (for example, 5 μm), it cannot function properly if foreign matter such as sludge gets into the servo valve. Therefore, when using a servo valve, it is necessary to take measures such as providing a filter to capture foreign matter, which can complicate the maintenance work of the hydraulic device.

[0006] An object of the present disclosure is to control the extrusion speed of a rod of a hydraulic cylinder in a hydraulic device that drives a hydraulic cylinder, without complicating maintenance work for the hydraulic device. [Means for solving the problem]

[0007] A first aspect of the present disclosure is a hydraulic device (10) that drives a hydraulic cylinder (100), and includes: a head-side passage (21) through which driving hydraulic oil flows and is supplied to a head chamber (104) of the hydraulic cylinder (100); a rod-side passage (22) through which driving hydraulic oil discharged from a rod chamber (105) of the hydraulic cylinder (100) flows; a control valve (40) that is provided in the rod-side passage (22) and operates in accordance with the pressure of the supplied control hydraulic oil to control the flow of the driving hydraulic oil in the rod-side passage (22); a pump (61) that supplies control hydraulic oil to the control valve (40); and a controller (70) that controls the pressure of the control hydraulic oil supplied by the pump (61) to the control valve (40).

[0008] In the first aspect, a control valve (40) is provided in the rod-side passage (22). The control valve (40) controls the flow of hydraulic oil flowing out from the rod chamber (105) of the hydraulic cylinder (100). The control valve (40) operates in response to the pressure of the control hydraulic oil supplied by the pump (61). The controller (70) controls the pressure of the hydraulic oil supplied to the control valve (40) by the pump (61). Therefore, the operation of the control valve (40) is controlled by the controller (70), and as a result, the extrusion speed of the rod of the hydraulic cylinder (100) is controlled. Furthermore, since the control valve (40) that operates in response to the pressure of the supplied control hydraulic oil is used, maintenance work on the hydraulic device (10) is not complicated.

[0009] A second aspect of the present disclosure is the first aspect, wherein the control valve (40) is a relief valve (41) whose operating pressure changes depending on the pressure of supplied control hydraulic oil.

[0010] In the second embodiment, the relief valve (41) is provided as the control valve (40) in the hydraulic device (10). The pressure at which the relief valve (41) operates varies depending on the pressure of the control hydraulic oil supplied to the relief valve (41) by the pump (61).

[0011] A third aspect of the present disclosure is the first aspect, wherein the control valve (40) is a flow rate adjustment valve (42) that changes the flow rate of the driving hydraulic oil passing through it depending on the pressure of the supplied control hydraulic oil.

[0012] In the third aspect, the flow rate adjustment valve (42) is provided as the control valve (40) in the hydraulic device (10). The flow rate of the driving hydraulic oil passing through the flow rate adjustment valve (42) varies depending on the pressure of the control hydraulic oil supplied to the flow rate adjustment valve (42) by the pump (61).

[0013] A fourth aspect of the present disclosure is any one of the first to third aspects, wherein the pump (61) performs both an operation of supplying control hydraulic oil to the control valve (40) and an operation of supplying drive hydraulic oil to the hydraulic cylinder (100) through the head-side passage (21).

[0014] In the fourth aspect, the pump (61) not only operates to supply control hydraulic oil to the control valve (40) but also operates to supply drive hydraulic oil to the head chamber (104) of the hydraulic cylinder (100). The pump (61) is used both to control the operation of the control valve (40) and to drive the hydraulic cylinder (100).

[0015] A fifth aspect of the present disclosure is any one of the first to fourth aspects, further comprising an on-off valve (51) arranged in parallel with the control valve (40) in the rod side passage (22) and controlling the flow of hydraulic oil for driving in the rod side passage (22).

[0016] In the fifth aspect, a control valve (40) and an on-off valve (51) are provided in parallel in the rod side passage (22). The hydraulic oil for driving that flows through the rod side passage (22) passes through the control valve (40) or the on-off valve (51).

[0017] A sixth aspect of the present disclosure is the fifth aspect, wherein the controller (70) opens the control valve (40) and then opens the on-off valve (51) when pushing out the rod (103) of the hydraulic cylinder (100).

[0018] When pushing out the rod (103) of the hydraulic cylinder (100), the controller (70) of the sixth aspect first opens the control valve (40) and then opens the on-off valve (51). As a result, the flow rate of the driving hydraulic oil flowing out from the rod chamber (105) of the hydraulic cylinder (100) to the rod-side passage (22) changes in two stages, and the moving speed of the rod-side passage (22) of the hydraulic cylinder (100) changes in two stages. The moving speed of the rod (103) in the first stage changes depending on the pressure of the control hydraulic oil supplied to the control valve (40) by the pump (61). [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a piping diagram of a hydraulic circuit showing the configuration of a hydraulic device according to a first embodiment. [Figure 2]FIG. 2 is a piping diagram of a hydraulic circuit showing the preparatory operation of the hydraulic device of the first embodiment. [Figure 3] FIG. 3 is a piping diagram of a hydraulic circuit showing the low-speed injection operation of the hydraulic device of the first embodiment. [Figure 4] FIG. 4 is a piping diagram of a hydraulic circuit showing the high-speed injection operation of the hydraulic device of the first embodiment. [Figure 5] FIG. 5 is a piping diagram of a hydraulic circuit showing the stopping operation of the hydraulic device of the first embodiment. [Figure 6] FIG. 6 is a piping diagram of a hydraulic circuit showing the backward movement of the hydraulic device of the first embodiment. [Figure 7] FIG. 7 is a piping diagram of a hydraulic circuit showing the configuration of a hydraulic device according to the second embodiment. [Figure 8] FIG. 8 is a piping diagram of a hydraulic circuit showing the preparatory operation of the hydraulic device of the second embodiment. [Figure 9] FIG. 9 is a piping diagram of a hydraulic circuit showing the low-speed injection operation of the hydraulic device of the second embodiment. [Figure 10] FIG. 10 is a piping diagram of a hydraulic circuit showing the high-speed injection operation of the hydraulic device of the second embodiment. [Figure 11] FIG. 11 is a piping diagram of a hydraulic circuit showing the stopping operation of the hydraulic device of the second embodiment. [Figure 12] FIG. 12 is a piping diagram of a hydraulic circuit showing the backward movement of the hydraulic device of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] First Embodiment The first embodiment will be described.

[0021] As shown in Fig. 1, the hydraulic device 10 of this embodiment drives a hydraulic cylinder 100 of a die-casting machine. The hydraulic cylinder 100 driven by the hydraulic device 10 of this embodiment drives a plunger that pushes out molten metal.

[0022] -Hydraulic cylinder- The hydraulic cylinder (100) is a single-rod cylinder. The hydraulic cylinder (100) includes a cylinder tube (101), a piston (102), and a rod (103). The internal space of the cylinder tube (101) is divided by the piston (102) into a head chamber (104) on the piston (102) side and a rod chamber (105) on the rod (103) side.

[0023] -Hydraulic system- The hydraulic device (10) includes a hydraulic circuit (20) and a controller (70). The hydraulic circuit (20) is connected to a hydraulic cylinder (100) of the die-casting machine. The controller (70) controls the devices provided in the hydraulic device (10).

[0024] <Hydraulic circuit> The hydraulic circuit (20) includes a pump unit (60), a tank (15), and an accumulator (16). The hydraulic circuit (20) also includes a relief valve (41), a first cartridge valve (51), a second cartridge valve (52), a switching valve (55), a first direction switching valve (56), a second direction switching valve (57), and a third direction switching valve (58).

[0025] In the hydraulic circuit (20), a plurality of components such as a pump unit (60) are connected by pipes. In the hydraulic circuit (20), hydraulic oil sucked out from a tank (15) is supplied to a hydraulic cylinder (100), and hydraulic oil discharged from the hydraulic cylinder (100) is returned to the tank (15).

[0026] In the hydraulic circuit (20), the hydraulic pump (61) of the pump unit (60) has an inlet connected to the tank (15). The discharge port of the hydraulic pump (61) is connected to a first port of the switching valve (55). The second port of the switching valve (55) is connected to a second port of the second cartridge valve (52). The piping from the discharge port of the hydraulic pump (61) to the second port of the second cartridge valve (52) forms a supply-side main passage (30).

[0027] A first port of the second cartridge valve (52) is connected to the head chamber (104) of the hydraulic cylinder (100). The piping from the second cartridge valve (52) to the head chamber (104) of the hydraulic cylinder (100) forms a first supply passage (31).

[0028] The first supply passage (31) and the supply-side main passage (30) form a head-side passage (21) through which the hydraulic oil for driving flows and is supplied to the head chamber (104) of the hydraulic cylinder (100). In the head-side passage (21), the selector valve (55) and the second cartridge valve (52) are connected in series.

[0029] The accumulator 16 is connected to a pipe connecting the switching valve 55 and the second cartridge valve 52. A die circuit (not shown) for driving a die of a die-casting machine is connected to a pipe connecting the discharge port of the hydraulic pump 61 and the switching valve 55.

[0030] A first port of the relief valve (41) and a first port of the first cartridge valve (51) are connected to a rod chamber (105) of the hydraulic cylinder (100). The piping connecting the relief valve (41) and the first cartridge valve (51) to the hydraulic cylinder (100) forms a second discharge passage (37). The second port of the relief valve (41) and a second port of the first cartridge valve (51) are connected to the tank (15). The piping connecting the relief valve (41) and the first cartridge valve (51) to the tank (15) forms a discharge-side main passage (35).

[0031] The second discharge passage (37) and the discharge-side main passage (35) form a rod-side passage (22) through which the hydraulic oil discharged from the rod chamber (105) of the hydraulic cylinder (100) flows. In the rod-side passage (22), the relief valve (41) and the first cartridge valve (51) are connected in parallel.

[0032] The third directional control valve (58) has a first port connected to a third port of the second cartridge valve (52) and a second port connected to the rod chamber (105) of the hydraulic cylinder (100). The piping connecting the third directional control valve (58) and the rod chamber (105) of the hydraulic cylinder (100) constitutes the second supply passage (32). The third directional control valve (58) has a third port connected to the head chamber (104) of the hydraulic cylinder (100) and a fourth port connected to the tank (15). The piping connecting the third directional control valve (58) and the head chamber (104) of the hydraulic cylinder (100) constitutes the first discharge passage (36).

[0033] A back pressure port of the relief valve (41) is connected to a pipe connecting a discharge port of the hydraulic pump (61) and the switching valve (55). The pipe connected to the back pressure port of the relief valve (41) forms a first pressure introducing passage (26) for supplying control hydraulic oil to the relief valve (41).

[0034] The back pressure port of the first cartridge valve (51) and the back pressure port of the second cartridge valve (52) are connected via a pipe between the switching valve (55) and the second cartridge valve (52) in the supply-side main passage (30). This pipe forms a second pressure introducing passage (27). In the second pressure introducing passage (27), the first cartridge valve (51) is connected to a first directional control valve (56), and the second cartridge valve (52) is connected to a second directional control valve (57).

[0035] In the second pressure introducing passage (27), a first port of the first directional control valve (56) and a first port of the second directional control valve (57) are connected to a portion of the supply main passage (30) between the switching valve (55) and the second cartridge valve (52). A second port of the first directional control valve (56) is connected to a back pressure port of the first cartridge valve (51). A second port of the second directional control valve (57) is connected to a back pressure port of the second cartridge valve (52).

[0036] The fourth port of the first directional control valve (56) and the fourth port of the second directional control valve (57) are connected to the tank, and the third port of the first directional control valve (56) and the third port of the second directional control valve (57) are sealed.

[0037] <Pump unit> The pump unit (60) includes a hydraulic pump (61) and an electric motor (62). The hydraulic pump (61) is a pump that draws hydraulic oil through a suction port and discharges it from a discharge port. The hydraulic pump (61) is a positive displacement fluid machine such as a swash plate pump. The electric motor (62) is connected to a drive shaft of the hydraulic pump (61) and drives the hydraulic pump (61).

[0038] The pump unit (60) includes a pump controller (63). The pump controller (63) controls the rotation speed of the hydraulic pump (61) by adjusting the rotation speed of the electric motor (62). The pump controller (63) controls the rotation speed of the hydraulic pump (61) so that the pressure of the hydraulic oil discharged from the hydraulic pump (61) becomes a set pressure.

[0039] <Relief valve> The relief valve (41) switches between an open state and a closed state depending on the back pressure. In the open state, the first port is in communication with the second port. In the closed state, the first port is isolated from the second port. The relief valve (41) allows or blocks the flow of hydraulic oil for driving in the rod-side passage (22). The maximum flow rate of the hydraulic oil passing through the relief valve (41) is smaller than the maximum flow rate of the hydraulic oil passing through the first cartridge valve (51).

[0040] The back pressure in the relief valve (41) is the pressure of the control hydraulic oil introduced from the first pressure introducing passage (26) to the back pressure port. The pressure at which the relief valve (41) switches from the closed state to the open state varies depending on the back pressure. As the back pressure increases, the pressure at which the relief valve (41) switches from the closed state to the open state increases. The relief valve (41) is "a control valve (40) that operates in response to the pressure of the control hydraulic oil supplied from the hydraulic pump and controls the flow of the drive hydraulic oil in the rod side passage (22)."

[0041] <First cartridge valve> The first cartridge valve (51) switches between an open state and a closed state depending on the back pressure. In the open state, the first port communicates with the second port. In the closed state, the first port is blocked from the second port. The first cartridge valve (51) allows or blocks the flow of hydraulic oil for driving in the rod side passage (22).

[0042] The back pressure in the first cartridge valve (51) is the pressure of the hydraulic oil for control introduced from the second pressure introducing passage (27) to the back pressure port. When the back pressure is sufficiently higher than the pressure of the hydraulic oil introduced to the first port, the first cartridge valve (51) is held in a closed state. When the back pressure becomes lower than the pressure of the hydraulic oil introduced to the first port to a certain extent, the first cartridge valve (51) switches from a closed state to an open state. The first cartridge valve (51) is "an open / close valve that is arranged in parallel with the relief valve (41) in the rod side passage (22) and controls the flow of the hydraulic oil for drive in the rod side passage (22)."

[0043] <Second cartridge valve> The second cartridge valve (52) switches between a first state and a second state depending on the back pressure. In the first state, the second port communicates with both the first port and the third port. In the second state, the second port communicates with the third port and is blocked from the first port. The second cartridge valve (52) allows and blocks the flow of hydraulic oil for driving in the head-side passage (21).

[0044] The back pressure in the second cartridge valve (52) is the pressure of the hydraulic oil for control introduced from the second pressure introducing passage (27) to the back pressure port. When the back pressure is sufficiently higher than the pressure of the hydraulic oil introduced to the second port, the second cartridge valve (52) is held in the second state. When the back pressure becomes lower than the pressure of the hydraulic oil introduced to the second port to a certain extent, the second cartridge valve (52) switches from the second state to the first state.

[0045] <Switching valve> The switching valve is equipped with a solenoid for actuation and can be switched between an open state and a closed state. In the open state, the first port is connected to the second port. In the closed state, the first port is isolated from the second port.

[0046] <1st directional control valve, 2nd directional control valve> The first directional control valve (56) and the second directional control valve (57) each include a driving solenoid and are switchable between a first state and a second state. In the first state, the first port communicates with the second port, and the third port communicates with the fourth port. In the second state, the first port communicates with the third port, and the second port communicates with the fourth port.

[0047] The first directional control valve (56) in the first state connects the back pressure port of the first cartridge valve (51) to the second pressure introducing passage (27). The first directional control valve (56) in the second state connects the back pressure port of the first cartridge valve (51) to the tank (15). By operating the first directional control valve (56), the first cartridge valve (51) is switched from one of the open state and the closed state to the other.

[0048] The second directional control valve (57) in the first state connects the back pressure port of the second cartridge valve (52) to the second pressure introducing passage (27). The second directional control valve (57) in the second state connects the back pressure port of the second cartridge valve (52) to the tank (15). By operating the second directional control valve (57), the second cartridge valve (52) is switched from one of the first state and the second state to the other.

[0049] <3rd directional control valve> The third directional control valve (58) is provided with a driving solenoid and is switchable between a first state, a second state, and a closed state. In the first state, the first port communicates with the second port, and the third port communicates with the fourth port. In the second state, the first port communicates with the third port, and the second port communicates with the fourth port. In the closed state, each of the first to fourth ports is isolated from the other ports.

[0050] <accumulator> The accumulator (16) is a hollow container-like member. The interior of the accumulator (16) is divided into an oil chamber and a gas chamber by a rubber bladder. The oil chamber of the accumulator (16) is in communication with the supply-side main passage (30) via a pipe.

[0051] Controller The controller (70) includes a microcomputer (71) and a memory device (72). The memory device (72) is a semiconductor memory. The memory device (72) stores software for operating the microcomputer (71). The controller (70) controls the switching valve (55), the first directional control valve (56), the second directional control valve (57), and the third directional control valve (58). The controller (70) also controls the pressure of the hydraulic oil discharged by the hydraulic pump (61) by transmitting a set pressure to the pump controller (63) of the pump unit (60).

[0052] - Driving operation - The operation of the hydraulic device 10 will be described. The hydraulic device 10 drives the hydraulic cylinder 100 by meter-out control. In one molding process of the die-casting machine, the hydraulic device 10 sequentially performs a preparatory operation, a low-speed injection operation, a high-speed injection operation, a stopping operation, and a retreating operation.

[0053] <Preparatory actions> The preparatory operation is an operation for keeping the relief valve (41) and the first cartridge valve (51) in the closed state and for keeping the second cartridge valve (52) in the second state. Here, the preparatory operation will be described with reference to FIG. 2.

[0054] In the preparatory operation, the controller (70) sets the set pressure to the first pressure. The pump controller (63) of the pump unit (60) controls the rotation speed of the hydraulic pump (61) so that the pressure of the hydraulic oil discharged from the hydraulic pump (61) becomes the set pressure (=first pressure).

[0055] The first pressure introducing passage (26) is connected to the back pressure port of the relief valve (41). Therefore, the back pressure of the relief valve (41) becomes the first pressure, and the relief valve (41) is kept closed.

[0056] In the preparatory operation, the controller (70) opens the switching valve (55), sets the first directional control valve (56) and the second directional control valve (57) to their first states, and closes the third directional control valve (58).

[0057] The hydraulic oil discharged from the hydraulic pump (61) passes through the selector valve (55) and is stored in the accumulator (16). Note that if the amount of hydraulic oil stored in the accumulator (16) is sufficiently large and the pressure of the hydraulic oil stored in the accumulator (16) is sufficiently high, the selector valve (55) may be closed.

[0058] The pressure of the hydraulic oil in the second pressure introducing passage (27) is substantially equal to the pressure (=first pressure) of the hydraulic oil discharged from the hydraulic pump (61). When the first directional control valve (56) is in the first state, the back pressure of the first cartridge valve (51) becomes the first pressure, and the first cartridge valve (51) is held in a closed state. When the second directional control valve (57) is in the first state, the back pressure of the second cartridge valve (52) becomes the first pressure, and the second cartridge valve (52) is held in the second state.

[0059] <Low speed injection operation> The low-speed injection operation is an operation in which the rod (103) of the hydraulic cylinder (100) is pushed out at a relatively low speed. The low-speed injection operation is an operation for pushing out molten metal at a low speed. The low-speed injection operation is performed for a very short time (for example, 50 to 100 ms). Here, the low-speed injection operation will be described with reference to FIG. 3.

[0060] In the low-speed injection operation, the controller (70) changes the set pressure from the first pressure to the second pressure. The second pressure is lower than the first pressure. The pump controller (63) of the pump unit (60) controls the rotation speed of the hydraulic pump (61) so that the pressure of the hydraulic oil discharged from the hydraulic pump (61) becomes the set pressure (= the second pressure). As a result, the back pressure of the relief valve (41) decreases from the first pressure to the second pressure.

[0061] In the low-speed injection operation, the controller (70) switches the switching valve (55) from an open state to a closed state, holds the first directional switching valve (56) in the first state, switches the second directional switching valve (57) from the first state to the second state, and holds the third directional switching valve (58) in the closed state.

[0062] The pressure of the hydraulic oil in the accumulator (16) and the second pressure introducing passage (27) is maintained at the first pressure. The first directional control valve (56) is maintained in the first state. Therefore, the back pressure of the first cartridge valve (51) is maintained at the first pressure, and the first cartridge valve (51) is maintained in the closed state. The second directional control valve (57) switches from the first state to the second state. Therefore, the back pressure of the second cartridge valve (52) becomes the pressure of the hydraulic oil in the tank (15) (substantially equal to atmospheric pressure), and the second cartridge valve (52) switches from the second state to the first state.

[0063] When the second cartridge valve (52) is in the first state, the hydraulic oil in the accumulator (16) flows through the head-side passage (21) and is supplied as driving hydraulic oil to the head chamber (104) of the hydraulic cylinder (100). The pressure of the hydraulic oil supplied to the head chamber (104) of the hydraulic cylinder (100) is substantially the first pressure.

[0064] When the hydraulic pressure in the head chamber (104) of the hydraulic cylinder (100) increases, the hydraulic pressure in the rod chamber (105) also increases. When the hydraulic pressure in the rod chamber (105) exceeds a predetermined pressure, the relief valve (41) switches from a closed state to an open state. As a result, the hydraulic oil in the rod chamber (105) of the hydraulic cylinder (100) is discharged to the tank (15) through the rod-side passage (22), and the rod (103) of the hydraulic cylinder (100) is pushed out.

[0065] As the back pressure (= second pressure) of the relief valve (41) increases, the difference in hydraulic pressure between the head chamber (104) and the rod chamber (105) decreases when the relief valve (41) opens and the rod (103) of the hydraulic cylinder (100) starts to move, resulting in a slower movement speed of the rod (103). Also, as the back pressure (= second pressure) of the relief valve (41) decreases, the difference in hydraulic pressure between the head chamber (104) and the rod chamber (105) increases when the relief valve (41) opens and the rod (103) of the hydraulic cylinder (100) starts to move, resulting in a faster movement speed of the rod (103). In this way, during the low-speed injection operation, the movement speed of the rod (103) of the hydraulic cylinder (100) can be adjusted by changing the back pressure of the relief valve (41).

[0066] <High-speed injection operation> The high-speed injection operation is an operation in which the rod (103) of the hydraulic cylinder (100) is pushed out at a relatively high speed. The high-speed injection operation is an operation for injecting molten metal into the mold of the die-casting machine at a high speed. Here, the high-speed injection operation will be described with reference to FIG. 4.

[0067] In the high-speed injection operation, similarly to the low-speed injection operation, the controller (70) sets the set pressure to the second pressure (< the first pressure). Therefore, the back pressure of the relief valve (41) becomes the second pressure. The relief valve (41) is in the open state, similarly to the low-speed injection operation.

[0068] In the high-speed injection operation, the controller (70) keeps the switching valve (55), the second directional control valve (57), and the third directional control valve (58) in the same states as in the low-speed injection operation, while switching the first directional control valve (56) from the first state to the second state.

[0069] As in the case of the low-speed injection operation, hydraulic oil for driving is supplied to the head chamber (104) of the hydraulic cylinder (100) from the accumulator (16) through the head-side passage (21).

[0070] The first directional control valve (56) switches from the first state to the second state, so that the back pressure of the first cartridge valve (51) becomes the pressure of the hydraulic oil in the tank (15) (substantially equal to atmospheric pressure), and the first cartridge valve (51) switches from the closed state to the open state.

[0071] In the high-speed injection operation, both the relief valve (41) and the first cartridge valve (51) are open. Therefore, compared with the low-speed injection operation, the flow rate of the hydraulic oil flowing out from the rod chamber (105) of the hydraulic cylinder (100) to the rod-side passage (22) is significantly increased, and the rod (103) of the hydraulic cylinder (100) is pushed out in one go at high speed.

[0072] <Stop operation> The stopping operation is an operation for stopping the rod 103 of the hydraulic cylinder 100 that has been pushed out by the high-speed injection operation. Here, the stopping operation will be described with reference to FIG.

[0073] In the stopping operation, the controller (70) changes the set pressure from the second pressure to the first pressure, so that the back pressure of the relief valve (41) changes from the second pressure to the first pressure, and the relief valve (41) switches from an open state to a closed state.

[0074] In the stopping operation, the controller (70) keeps the switching valve (55) and the third directional switching valve (58) in the same states as in the high-speed injection operation, while switching the first directional switching valve (56) and the second directional switching valve (57) from the second state to the first state.

[0075] When the second directional control valve (57) is in the first state, the back pressure of the second cartridge valve (52) becomes equal to the pressure of the hydraulic oil in the accumulator (≈first pressure), and the second cartridge valve (52) switches from the first state to the second state, thereby stopping the supply of hydraulic oil to the head chamber (104) of the hydraulic cylinder (100).

[0076] When the first directional control valve (56) is in the first state, the back pressure of the first cartridge valve (51) becomes equal to the pressure of the hydraulic oil in the accumulator (16) (≈first pressure), and the first cartridge valve (51) switches from the open state to the closed state. As described above, in the stopping operation, the relief valve (41) is closed. Therefore, the discharge of the hydraulic oil from the rod chamber (105) of the hydraulic cylinder (100) stops.

[0077] In this manner, during the stopping operation, the supply of hydraulic oil to the head chamber (104) of the hydraulic cylinder (100) is stopped, and the discharge of hydraulic oil from the rod chamber (105) of the hydraulic cylinder (100) is stopped, thereby stopping the rod (103) of the hydraulic cylinder (100).

[0078] <Retreating movement> The retreating operation is an operation of pulling back the rod 103 of the hydraulic cylinder 100. Here, the retreating operation will be described with reference to FIG.

[0079] In the retraction operation, the controller (70) maintains the set pressure at the first pressure, so that the back pressure of the relief valve (41) is maintained at the first pressure, and the relief valve (41) is maintained in a closed state.

[0080] In the stopping operation, the controller (70) keeps the switching valve (55), the first directional switching valve (56), and the second directional switching valve (57) in the same states as in the stopping operation, while switching the third directional switching valve (58) from the closed state to the first state.

[0081] When the third directional control valve (58) is in the first state, the hydraulic oil in the accumulator (16) passes through the second cartridge valve (52) and the third directional control valve (58) in this order and is supplied to the rod chamber (105) of the hydraulic cylinder (100). When the third directional control valve (58) is in the first state, the head chamber (104) of the hydraulic cylinder (100) communicates with the tank (15), and the hydraulic oil in the head chamber (104) is discharged to the tank (15). As a result, the rod (103) of the hydraulic cylinder (100) is pulled back toward the head chamber (104).

[0082] -Feature (1) of the first embodiment- In the hydraulic device (10) of this embodiment, a control valve (40) is provided in the rod-side passage (22). The control valve (40) controls the flow of hydraulic oil flowing out of the rod chamber (105) of the hydraulic cylinder (100). The control valve (40) operates in response to the pressure of control hydraulic oil supplied by the hydraulic pump (61). The controller (70) controls the pressure of the hydraulic oil supplied to the control valve (40) by the hydraulic pump (61). Therefore, the operation of the control valve (40) is controlled by the controller (70), and as a result, the extrusion speed of the rod (103) of the hydraulic cylinder (100) is controlled. Furthermore, since the control valve (40) that operates in response to the pressure of the supplied control hydraulic oil is used, maintenance of the hydraulic device (10) is not complicated.

[0083] In particular, the hydraulic device 10 of this embodiment is provided with a relief valve 41 as the control valve 40. In this embodiment, by using the relief valve 41, which is easier to maintain and more reliable than a servo valve, it is possible to control the extrusion speed of the rod 103 of the hydraulic cylinder 100 without complicating the maintenance of the hydraulic device 10.

[0084] -Feature (2) of the first embodiment- In the hydraulic system (10) of this embodiment, the hydraulic pump (61) supplies hydraulic oil to the accumulator (16) in the preparation for injection. The hydraulic oil stored in the accumulator (16) is supplied to the head chamber (104) of the hydraulic cylinder (100) as driving hydraulic oil in the low-speed injection operation and the high-speed injection operation. In this manner, the hydraulic pump (61) supplies driving hydraulic oil to the hydraulic cylinder (100) via the accumulator (16). The hydraulic pump (61) also supplies control hydraulic oil to the relief valve (41) in each of the preparation operation, the low-speed injection operation, the high-speed injection operation, the stopping operation, and the retraction operation. Therefore, in the hydraulic system (10) of this embodiment, the hydraulic pump (61) of the pump unit (60) is used both to control the operation of the relief valve (41), which is the control valve (40), and to drive the hydraulic cylinder (100).

[0085] Second Embodiment A second embodiment will now be described.

[0086] 7, the hydraulic system (10) of the present embodiment includes a throttle valve (42) instead of the relief valve (41) of the first embodiment. Here, differences between the hydraulic system (10) of the present embodiment and the hydraulic system (10) of the first embodiment will be described.

[0087] In the hydraulic circuit (20) of this embodiment, a first port of the throttle valve (42) is connected to the rod chamber (105) of the hydraulic cylinder (100) via the second discharge passage (37). A second port of the throttle valve (42) is connected to the tank (15) via the discharge-side main passage (35). In the rod-side passage (22) of the hydraulic circuit (20) of this embodiment, the throttle valve (42) and the first cartridge valve (51) are connected in parallel. A back pressure port of the throttle valve (42) is connected to a pipe connecting the discharge port of the hydraulic pump (61) and the switching valve (55) via the first pressure introducing passage (26).

[0088] <Throttling valve> The throttle valve (42) switches between an open state and a closed state depending on the back pressure. In the open state, the first port is connected to the second port. In the closed state, the first port is blocked from the second port. The throttle valve (42) allows or blocks the flow of hydraulic oil for driving in the rod-side passage (22). When the throttle valve (42) is in the open state, the opening degree thereof changes depending on the back pressure. When the opening degree of the throttle valve (42) changes, the flow rate of the hydraulic oil passing through the throttle valve (42) changes. The maximum value of the flow rate of the hydraulic oil passing through the throttle valve (42) is smaller than the maximum value of the flow rate of the hydraulic oil passing through the first cartridge valve (51).

[0089] The back pressure in the throttle valve (42) is the pressure of the control hydraulic oil introduced from the first pressure introducing passage (26) to the back pressure port. The opening of the throttle valve (42) changes depending on the back pressure. As the back pressure of the throttle valve (42) increases, the opening of the throttle valve (42) increases. The throttle valve (42) is a "flow rate control valve that changes the flow rate of the driving hydraulic oil passing through it depending on the pressure of the supplied control hydraulic oil." Similarly to the relief valve (41) of the first embodiment, the throttle valve (42) is a "control valve (40) that operates depending on the pressure of the control hydraulic oil supplied from the hydraulic pump and controls the flow of the driving hydraulic oil in the rod side passage (22)."

[0090] - Driving operation - The operation of the hydraulic system 10 will be described. The hydraulic system 10 of this embodiment, like the hydraulic system 10 of the first embodiment, performs a preparatory operation, a low-speed injection operation, a high-speed injection operation, a stopping operation, and a retreating operation in that order in one molding process of a die-casting machine. Here, the differences between these operations and the hydraulic system 10 of the first embodiment will be mainly described.

[0091] <Preparatory actions> The preparatory operation of this embodiment is an operation for keeping the throttle valve (42) and the first cartridge valve (51) in a closed state and for keeping the second cartridge valve (52) in the second state. Here, the preparatory operation of this embodiment will be described with reference to Fig. 8. Note that Fig. 8 shows the preparatory operation in a state in which a sufficient amount of hydraulic oil at the first pressure is stored in the accumulator (16).

[0092] In the preparatory operation, the controller (70) sets the set pressure to a third pressure. The third pressure is lower than the first pressure. The pump controller (63) of the pump unit (60) controls the rotation speed of the hydraulic pump (61) so that the pressure of the hydraulic oil discharged from the hydraulic pump (61) becomes the set pressure (=the third pressure).

[0093] The first pressure introducing passage (26) is connected to the back pressure port of the throttle valve (42), so that the back pressure of the throttle valve (42) becomes the third pressure, and the throttle valve (42) is maintained in a closed state.

[0094] In the preparatory operation, the controller (70) closes the switching valve (55), sets the first directional control valve (56) and the second directional control valve (57) to their first states, and closes the third directional control valve (58).

[0095] The pressure of the hydraulic oil in the second pressure introducing passage (27) is substantially equal to the pressure (=first pressure) of the hydraulic oil stored in the accumulator (16). When the first directional control valve (56) is in the first state, the back pressure of the first cartridge valve (51) becomes the first pressure, and the first cartridge valve (51) is held in a closed state. When the second directional control valve (57) is in the first state, the back pressure of the second cartridge valve (52) becomes the first pressure, and the second cartridge valve (52) is held in the second state.

[0096] <Low speed injection operation> The low-speed injection operation of this embodiment is an operation of pushing out the rod (103) of the hydraulic cylinder (100) at a relatively low speed, similar to the low-pressure injection operation of Embodiment 1. Here, the low-speed injection operation of this embodiment will be described with reference to FIG.

[0097] In the low-speed injection operation, the controller (70) holds the switching valve (55) in a closed state, holds the first directional control valve (56) in a first state, switches the second directional control valve (57) from the first state to the second state, and holds the third directional control valve (58) in a closed state.

[0098] The first directional control valve (56) is maintained in the first state. Therefore, the back pressure of the first cartridge valve (51) is maintained at the first pressure, and the first cartridge valve (51) is maintained in the closed state. The second directional control valve (57) switches from the first state to the second state. Therefore, the back pressure of the second cartridge valve (52) becomes the pressure of the hydraulic oil in the tank (15) (substantially equal to atmospheric pressure), and the second cartridge valve (52) switches from the second state to the first state.

[0099] In the low-speed injection operation, the controller (70) changes the set pressure from the third pressure to the fourth pressure. The fourth pressure is higher than the third pressure. The pump controller (63) of the pump unit (60) controls the rotation speed of the hydraulic pump (61) so that the pressure of the hydraulic oil discharged from the hydraulic pump (61) becomes the set pressure (=the fourth pressure). Therefore, the back pressure of the throttle valve (42) increases from the third pressure to the fourth pressure. When the back pressure of the throttle valve (42) becomes the fourth pressure, the throttle valve (42) switches from the closed state to the open state.

[0100] When the second cartridge valve (52) is in the first state, the hydraulic oil in the accumulator (16) flows through the head-side passage (21) and is supplied as driving hydraulic oil to the head chamber (104) of the hydraulic cylinder (100). When the throttle valve (42) is in the open state, the hydraulic oil in the rod chamber (105) of the hydraulic cylinder (100) is discharged to the tank (15) through the rod-side passage (22). As a result, the rod (103) of the hydraulic cylinder (100) is pushed out.

[0101] As described above, the opening degree of the throttle valve (42) changes depending on the back pressure. As the back pressure of the throttle valve (42) increases, the opening degree of the throttle valve (42) increases. As a result, the flow rate of hydraulic oil flowing out of the rod chamber (105) of the hydraulic cylinder (100) increases, and the movement speed of the rod (103) increases. Also, as the back pressure of the throttle valve (42) decreases, the opening degree of the throttle valve (42) decreases. As a result, the flow rate of hydraulic oil flowing out of the rod chamber (105) of the hydraulic cylinder (100) decreases, and the movement speed of the rod (103) decreases. In this way, in the low-speed injection operation, the movement speed of the rod (103) of the hydraulic cylinder (100) can be adjusted by changing the back pressure of the throttle valve (42).

[0102] <High-speed injection operation> The high-speed injection operation of this embodiment is an operation of pushing out the rod (103) of the hydraulic cylinder (100) at a relatively high speed, similar to the high-pressure injection operation of Embodiment 1. Here, the high-speed injection operation will be described with reference to FIG.

[0103] In the high-speed injection operation, the controller (70) sets the set pressure to a fifth pressure. The fifth pressure is equal to or greater than the fourth pressure. Therefore, the back pressure of the throttle valve (42) becomes equal to the fifth pressure. The opening of the throttle valve (42) becomes equal to or greater than the opening of the throttle valve (42) in the low-speed injection operation.

[0104] In the high-speed injection operation, the controller (70) keeps the switching valve (55), the second directional control valve (57), and the third directional control valve (58) in the same states as in the low-speed injection operation, while switching the first directional control valve (56) from the first state to the second state.

[0105] As in the case of the low-speed injection operation, hydraulic oil for driving is supplied to the head chamber (104) of the hydraulic cylinder (100) from the accumulator (16) through the head-side passage (21).

[0106] The first directional control valve (56) switches from the first state to the second state, so that the back pressure of the first cartridge valve (51) becomes the pressure of the hydraulic oil in the tank (15) (substantially equal to atmospheric pressure), and the first cartridge valve (51) switches from the closed state to the open state.

[0107] In the high-speed injection operation, both the throttle valve (42) and the first cartridge valve (51) are open. Therefore, compared with the low-speed injection operation, the flow rate of the hydraulic oil flowing from the rod chamber (105) of the hydraulic cylinder (100) to the rod-side passage (22) is significantly increased, and the rod (103) of the hydraulic cylinder (100) is pushed out in one go at high speed.

[0108] <Stop operation> The stopping operation of this embodiment is an operation for stopping the rod (103) of the hydraulic cylinder (100) that has been pushed out by the high-speed injection operation, similar to the stopping operation of Embodiment 1. Here, the stopping operation of this embodiment will be described with reference to FIG.

[0109] In the stopping operation, the controller (70) outputs a stop command to the pump controller (63) of the pump unit (60). In the pump unit (60), the pump controller (63) receives the stop command and stops the electric motor (62). As a result, the hydraulic pump (61) stops. When the hydraulic pump (61) stops, the back pressure of the throttle valve (42) drops to or below the third pressure. As a result, the throttle valve (42) switches from the open state to the closed state.

[0110] In the stopping operation, the controller (70) may set the set pressure to the third pressure. In this case, the back pressure of the throttle valve (42) decreases to the third pressure, and the throttle valve (42) switches from the open state to the closed state.

[0111] In the stopping operation, the controller (70) keeps the switching valve (55) and the third directional switching valve (58) in the same states as in the high-speed injection operation, while switching the first directional switching valve (56) and the second directional switching valve (57) from the second state to the first state.

[0112] As in the stopping operation of the first embodiment, when the second directional control valve (57) is set to the first state, the second cartridge valve (52) switches from the first state to the second state, and the supply of hydraulic oil to the head chamber (104) of the hydraulic cylinder (100) is stopped. Furthermore, as in the stopping operation of the first embodiment, when the first directional control valve (56) is set to the first state, the first cartridge valve (51) switches from the open state to the closed state, and the discharge of hydraulic oil from the rod chamber (105) of the hydraulic cylinder (100) is stopped.

[0113] In this manner, during the stopping operation, the supply of hydraulic oil to the head chamber (104) of the hydraulic cylinder (100) is stopped, and the discharge of hydraulic oil from the rod chamber (105) of the hydraulic cylinder (100) is stopped, thereby stopping the rod (103) of the hydraulic cylinder (100).

[0114] <Retreating movement> The retreating operation of this embodiment is an operation of pulling back the rod (103) of the hydraulic cylinder (100), similar to the shifting operation of Embodiment 1. Here, the retreating operation will be described with reference to FIG.

[0115] In the reverse operation, following the stop operation, the controller (70) outputs a stop command to the pump controller (63) of the pump unit (60), so that the hydraulic pump (61) is kept stopped and the throttle valve (42) is kept closed.

[0116] In the reverse operation, the controller (70) may set the set pressure to the third pressure, as in the stop operation. In this case, the throttle valve (42) is also kept closed, as in the case where the hydraulic pump (61) is stopped.

[0117] In the stopping operation, the controller (70) keeps the switching valve (55), the first directional switching valve (56), and the second directional switching valve (57) in the same states as in the stopping operation, while switching the third directional switching valve (58) from the closed state to the first state.

[0118] When the third directional control valve (58) is in the first state, the hydraulic oil in the accumulator (16) passes through the second cartridge valve (52) and the third directional control valve (58) in this order and is supplied to the rod chamber (105) of the hydraulic cylinder (100). When the third directional control valve (58) is in the first state, the head chamber (104) of the hydraulic cylinder (100) communicates with the tank (15), and the hydraulic oil in the head chamber (104) is discharged to the tank (15). As a result, the rod (103) of the hydraulic cylinder (100) is pulled back toward the head chamber (104).

[0119] -Features of the second embodiment- The hydraulic device 10 of this embodiment is provided with a throttle valve 42 as the control valve 40. In this embodiment, by using the throttle valve 42, which is easier to maintain and more reliable than a servo valve, it is possible to control the extrusion speed of the rod 103 of the hydraulic cylinder 100 without complicating the maintenance of the hydraulic device 10.

[0120] Other Embodiments The hydraulic devices of the first and second embodiments are used to drive hydraulic cylinders of a die-casting machine, but the use of the hydraulic devices is not limited to this. The hydraulic devices (10) of the first and second embodiments may also be used to drive hydraulic cylinders for injection provided in an injection molding machine.

[0121] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and detail are possible without departing from the spirit and scope of the claims. Furthermore, elements of the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate. Furthermore, the terms "first," "second," "third," etc. in the specification and claims are used to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Industrial Applicability]

[0122] As described above, the present disclosure is useful for hydraulic devices. [Explanation of symbols]

[0123] 10 Hydraulic System () 21 Head side passage () 22 Rod side passage () 40 Control valve () 41 Relief valve () 42 Flow Control Valve () 51 First cartridge valve (on-off valve) 61 Hydraulic pump (pump) 70 Controller 100 hydraulic cylinders 104 Head Chamber 105 Rod Room

Claims

1. A hydraulic device (10) that drives a hydraulic cylinder (100), a head-side passage (21) through which hydraulic oil for driving flows, the hydraulic oil being supplied to a head chamber (104) of the hydraulic cylinder (100); a rod-side passage (22) through which hydraulic oil for driving flows discharged from a rod chamber (105) of the hydraulic cylinder (100); a control valve (40) that is provided in the rod side passage (22), that operates in response to the pressure of the supplied control hydraulic oil, and that controls the flow of the driving hydraulic oil in the rod side passage (22); a pump (61) for supplying hydraulic oil for control to the control valve (40); a controller (70) for controlling the pressure of the control hydraulic oil supplied by the pump (61) to the control valve (40). Hydraulic system.

2. The control valve (40) is a relief valve (41) whose operating pressure changes depending on the pressure of the supplied hydraulic oil for control. The hydraulic system of claim 1 .

3. The control valve (40) is a flow rate adjusting valve (42) that changes the flow rate of the driving hydraulic oil passing through it in accordance with the pressure of the supplied control hydraulic oil. The hydraulic system of claim 1 .

4. The pump (61) performs both an operation of supplying control hydraulic oil to the control valve (40) and an operation of supplying drive hydraulic oil to the hydraulic cylinder (100) through the head side passage (21). The hydraulic device according to any one of claims 1 to 3.

5. an on-off valve (51) arranged in parallel with the control valve (40) in the rod side passage (22) and controlling the flow of hydraulic oil for driving in the rod side passage (22); The hydraulic device according to any one of claims 1 to 3.

6. When pushing out the rod (103) of the hydraulic cylinder (100), the controller (70) opens the control valve (40) and then opens the on-off valve (51). The hydraulic system according to claim 5.

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