JP2020051585A - Hydraulic equipment for construction machine - Google Patents

Abstract

To provide a hydraulic equipment capable of supplying hydraulic oil to a hoisting motor via a traveling motor, in which when the hoisting motor and the traveling motor are operated simultaneously, it is prevented that both pressures in the inlet and outlet sides of the hydraulic oil of the traveling motor become high level.SOLUTION: It is provided a switching valve 35 connected to two oil passages 11a, 11b allowing hydraulic oil to flow between a directional switching valve 5 for a traveling motor 2 and the traveling motor 2, which may shift to a first state where the oil passages 11a, 11b are communicated with each other or a second state where the communication is shut off. The switching valve 35 is configured so as to switch from the second state to the first state when the pressure of the hydraulic oil supplied from a directional switching valve 6 for a hoisting motor 3 to the hoisting motor 3 becomes higher than a predetermined value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a hydraulic device for a construction machine having a traveling hydraulic motor, such as a mobile crane, and a hydraulic motor for driving a hoisting device.

  Conventionally, in this type of construction machine, a hydraulic circuit (a hydraulic circuit including a directional control valve for controlling operation of a traveling motor) supplies hydraulic oil from a hydraulic pump to a traveling hydraulic motor (hereinafter, sometimes simply referred to as a traveling motor). A hydraulic circuit (a hydraulic circuit including a directional control valve for controlling the operation of the hoist motor) that supplies hydraulic oil to a hydraulic motor for driving the hoist (hereinafter sometimes simply referred to as a hoist motor) downstream of the circuit). Are connected in series, and when the operation of the respective hydraulic motors is performed so that the operation of the traveling motor and the operation of the hoisting motor are simultaneously performed, the hydraulic oil after passing the traveling motor from the hydraulic pump (the 2. Description of the Related Art There is known a device including a hydraulic device configured to supply hydraulic fluid discharged from a traveling motor to a hoist motor (for example, see Patent Document 1).

JP 2002-46978 A

  Since the hydraulic device as described above can arrange the direction switching valve for the traveling motor on the most upstream side, it is easy to configure an oil passage connecting the direction switching valve to the traveling motor via a swivel joint or the like, or Although there is an advantage that a dedicated oil passage for supplying hydraulic oil from the hydraulic pump to the directional control valve for the hoist motor can be omitted (thus, the cost and size of the valve unit can be reduced), the following advantages are obtained. It has been found from the study of the inventor of the present application that such inconvenience may occur.

  In other words, the load of the hoist motor often becomes large, for example, when lifting heavy objects. In such a situation where the load of the hoisting motor is large, when hydraulic oil is supplied to the traveling motor in order to operate the traveling motor, the inlet and outlet sides of the hydraulic oil of the traveling motor are supplied. Both of these pressures are high. As a result, there is a possibility that a malfunction of the traveling motor or damage to components such as a cylinder block of the traveling motor may occur.

  The present invention has been made in view of such a background, and in a hydraulic device capable of supplying hydraulic oil to a hoisting motor via a traveling motor, when the winding motor and the traveling motor are simultaneously operated, the traveling motor It is an object of the present invention to provide a hydraulic device capable of preventing a pressure on both an inlet side and an outlet side of hydraulic oil from becoming high.

A traveling motor that is a traveling hydraulic motor, a hoisting motor that is a hydraulic motor for driving a hoisting device, a hydraulic pump that discharges hydraulic oil, and a traveling switching valve that is a direction switching valve connected to the traveling motor. A hoist switching valve that is a directional switching valve connected to the hoist motor, wherein the travel switching valve is configured such that the operating oil discharged from the hydraulic pump flows upstream of the hoist switching valve. The hoisting switching valve is connected to the hydraulic pump, and when the operation oil of the traveling motor is stopped, the hydraulic oil discharged from the hydraulic switching valve flows in through the traveling switching valve, and the traveling motor A hydraulic device for a construction machine connected to the travel switching valve so as to flow in through the travel switching valve and the travel motor when the is operated,
A first state in which the two traveling motor oil passages are connected to each other so that hydraulic oil flows between the traveling switching valve and the traveling motor and the two traveling motor oil passages are communicated with each other; A switching valve operable in a second state, wherein when the pressure of the hydraulic oil supplied from the hoisting switching valve to the hoisting motor becomes a high pressure equal to or higher than a predetermined value, the switching valve It is configured to operate according to the pressure so as to switch from the second state to the first state (first invention).

  In the present invention, the “two traveling motor oil passages” are defined as an oil passage through which one of the traveling motor oil passages flows the operating oil supplied from the traveling switching valve to the traveling motor when the traveling motor is operated, The traveling motor oil passages mean two oil passages that serve as oil passages for flowing hydraulic oil discharged from the traveling motor to the traveling switching valve.

  According to the first aspect, when the pressure of the operating oil supplied to the hoist motor becomes a high pressure equal to or higher than a predetermined value, the state is switched from the second state to the first state. The oil passages communicate with each other. For this reason, when the traveling motor and the hoist motor are simultaneously operated and the pressure of the hydraulic oil supplied to the hoist motor becomes high, the hydraulic oil discharged from the hydraulic pump does not pass through the travel motor. Is supplied to the hoisting motor. Thus, it is possible to prevent the pressure on both the inlet side and the outlet side of the operating oil of the traveling motor from becoming high.

  In the first invention, the switching valve operates between the hoist switching valve and the hoist motor such that the pressure of the hydraulic oil supplied from the hoist switching valve to the hoist motor is applied as pilot pressure. It is preferable that the switching valve be a pilot-driven switching valve that is connected to two hoist motor oil passages through which oil flows through a pilot oil passage (a second invention).

  The “two hoist motor oil passages” include an oil passage through which one of the hoist motor oil passages flows hydraulic oil supplied from the hoist switching valve to the hoist motor when the hoist motor operates, and the other hoist motor oil passage. The oil passage means two oil passages that serve as oil passages for flowing the hydraulic oil discharged from the hoist motor to the hoist switching valve.

  According to the second aspect, a configuration for operating the switching valve can be simply and inexpensively configured.

  In the second invention, the pilot oil passage is provided with a check valve and a throttle portion connected in parallel with each other, and the check valve is provided between the hoist motor oil passage and the switching valve. It is preferable that the configuration is such that the flow of the hydraulic oil in the direction opposite to the direction in which the fluid flows is prevented (third invention).

  According to this, when the switching valve returns from the first state to the second state in response to a decrease in the pressure of the hydraulic oil supplied to the hoist motor, the pilot pressure applied to the switching valve gradually increases. Because of the decrease, the communication between the two traveling motor oil passages is gradually cut off. For this reason, when the switching valve returns to the second state from the first state, even if the traveling switching valve is driven to operate the traveling motor, the operating oil is rapidly supplied to the traveling motor. It can be prevented from being supplied. As a result, it is possible to prevent the abrupt operation of the traveling motor from starting.

FIG. 1 is a diagram illustrating a schematic configuration of a construction machine (mobile crane) to which an embodiment of the present invention is applied. FIG. 2 is a diagram illustrating a hydraulic circuit configuration of the hydraulic device according to the embodiment.

  One embodiment of the present invention will be described below with reference to FIGS. Referring to FIG. 1, a construction machine 50 including a hydraulic device 1 (shown in FIG. 2) of the present embodiment is, for example, a mobile crane. The construction machine 50 includes a lower traveling body 51 having a pair of left and right crawlers 51a, an upper revolving body 52 pivotally mounted on the lower traveling body 51, and swinging from the upper revolving body 52 via a boom foot pin 53. A boom 54 extending movably (up and down), a hydraulic cylinder 55 for performing an up / down operation of the boom 54, a hoisting device 56 (winch) mounted on the upper swing body 52 at the rear side of the boom 54, A wire 58 connected from a hoisting device 56 to a hook 59 below the point jeep 57 via a point jeep 57 (pulley mechanism) attached to the upper end of the boom 54, and the wire 58 is mounted on the upper swing body 52. And a driver's cab 60.

  In the construction machine 50, the wire 58 is run by the hoisting device 56 while the load is hung on the hook 59, or the boom 54 is raised and lowered by the hydraulic cylinder 55, or a turning operation (not shown) is performed. By carrying out the turning operation of the upper turning body 52 by the hydraulic motor, it is possible to move the load.

  The hydraulic device 1 of the present embodiment is mounted on such a construction machine 50, and as shown in FIG. 2, a traveling motor 2 that is a traveling hydraulic motor, and a hydraulic motor (a driving motor of a hoisting device 56). More specifically, the hoist motor 3, which is a hydraulic motor that rotationally drives the drum of the hoist 56, the hydraulic pump 4, the travel switching valve 5 that is a direction switching valve for controlling the operation of the travel motor 2, And a hoisting switching valve 6 which is a direction switching valve for operation control.

  The construction machine 50 includes two traveling motors for individually driving the left and right crawlers 51a constituting the lower traveling body 51. The travel motor 2 shown in FIG. 2 is one of the two travel motors.

  The hydraulic pump 4 is driven by an engine (not shown). In the driven state, the hydraulic pump 4 discharges the hydraulic oil from the discharge port while sucking the hydraulic oil from the hydraulic oil tank 7. A center bypass oil passage 10 is connected to the discharge port of the hydraulic pump 4 so as to return to the hydraulic oil tank 7 from the discharge port via the travel switching valve 5 and the hoisting switching valve 6 in this order. I have.

  The travel switching valve 5 interposed on the upstream side in the center bypass oil passage 10 is a pilot-driven directional switching valve having a spool valve, and has two pilot ports 5a and 5b. The travel switching valve 5 has, as its operation positions, a neutral position A0 position, an Aa position which is an operation position when a pilot pressure equal to or more than a predetermined value is applied to the pilot port 5a, and a predetermined value at the pilot port 5b. Ab position, which is the operating position when the above pilot pressure is applied.

  The travel switching valve 5 is provided with two inlet / outlet ports 2a, 2b (inlet or outlet of hydraulic oil) of the travel motor 2 through two oil paths 11a, 11b as travel motor oil paths in the present invention. 2) and is connected to the hydraulic oil tank 7 via an oil passage 12. In the present embodiment, the counterbalance valve 30 is interposed in the oil passages 11a and 11b, which will be described later.

  The travel switching valve 5 is biased to be held at the neutral position A0 when no pilot pressure is applied to both the pilot ports 5a and 5b. In the A0 position, the travel switching valve 5 opens the center bypass oil passage 10 on the upstream side to the center bypass oil passage 10 on the downstream side, and further, the oil passage among the oil passages 11a and 11b on the traveling motor 2 side. It is configured to close the valve 11 a and open the oil passage 11 b to the hydraulic oil tank 7 via the oil passage 12.

  Accordingly, at the A0 position (neutral position) of the travel switching valve 5, the operating oil flowing into the travel switching valve 6 from the hydraulic pump 4 via the upstream center bypass oil passage 10 is not supplied to the travel motor 2. , Flows into the center bypass oil passage 10 on the downstream side of the travel switching valve 6.

  When a pilot pressure equal to or greater than a predetermined value is applied to the pilot port 5a, the travel switching valve 5 is displaced from the A0 position (neutral position) to the Aa position as the pilot pressure increases. In the Aa position, the travel switching valve 5 closes the center bypass oil passage 10 on the upstream side with respect to the center bypass oil passage 10 on the downstream side, and opens the oil passage 11a on the travel motor 2 side. The oil passage 11b on the traveling motor 2 side is opened to the center bypass oil passage 10 on the downstream side.

  Further, in the process of displacing the travel switching valve 5 from the A0 position to the Aa position, the opening of the oil passage (bleed-off oil passage) between the upstream center bypass oil passage 10 and the downstream center bypass oil passage 10 is performed. Becomes gradually smaller as the pilot pressure applied to the pilot port 5a increases, or the opening of the oil passage (meter-in oil passage) between the upstream center bypass oil passage 10 and the oil passage 11a is It is configured to gradually increase as the pilot pressure applied to the port 5a increases.

  Therefore, when the travel switching valve 5 is operated to the Aa position side, the operating oil flowing from the hydraulic pump 4 into the travel switching valve 6 via the upstream center bypass oil passage 10 flows from the travel switching valve 5 to the oil passage 11a. Hydraulic oil supplied to the inlet / outlet port 2a of the traveling motor 2 via the other inlet / outlet port 2b of the traveling motor 2 via the oil passage 11b and the traveling switching valve 5 on the Aa position side. , And flows through the center bypass oil passage 10 on the downstream side. Further, as the pilot pressure applied to the pilot port 5a increases, the flow rate of the working oil supplied to the inlet / outlet port 2a of the traveling motor 2 increases.

  When a pilot pressure equal to or greater than a predetermined value is applied to the pilot port 5b, the travel switching valve 5 is displaced from the A0 position (neutral position) to the Ab position as the pilot pressure increases. At this Ab position, the travel switching valve 5 closes the center bypass oil passage 10 on the upstream side with respect to the center bypass oil passage 10 on the downstream side, and opens the oil passage 11b on the travel motor 2 side. The configuration is such that the oil passage 11a on the traveling motor 2 side is opened to the center bypass oil passage 10 on the downstream side.

  Furthermore, in the process of displacing the travel switching valve 5 from the A0 position to the Ab position, the opening of the oil passage (bleed-off oil passage) between the upstream center bypass oil passage 10 and the downstream center bypass oil passage 10 is performed. Decreases gradually with an increase in pilot pressure applied to the pilot port 5b, or the opening of the oil passage (meter-in oil passage) between the upstream center bypass oil passage 10 and the oil passage 11b is It is configured to gradually increase as the pilot pressure applied to the port 5b increases.

  Therefore, when the travel switching valve 5 is operated to the Ab position side, the operating oil flowing from the hydraulic pump 4 into the travel switching valve 6 via the upstream center bypass oil passage 10 flows from the travel switching valve 5 to the oil passage 11b. Hydraulic oil supplied to the inlet / outlet port 2b of the travel motor 2 via the other inlet / outlet port 2a of the travel motor 2 passes through the oil passage 11a and the travel switching valve 5 at the Ab position. The oil flows through the center bypass oil passage 10 on the downstream side. Further, as the pilot pressure applied to the pilot port 5b increases, the flow rate of the working oil supplied to the inlet / outlet port 2b of the traveling motor 2 increases.

  Each of the pilot ports 5a and 5b of the traveling switching valve 5 is connected to an operating device 13 provided with an operating lever 13a (or an operating pedal) for operating the traveling motor 2 via respective pilot oil passages 14a and 14b. Have been.

  The operating device 13 generates a pilot pressure (secondary pressure) in accordance with the operation of the operating lever 13a by a pressure reducing valve or the like from a primary pressure pilot hydraulic oil supplied from a pilot pump (not shown). Of the pilot ports 5a and 5b, the signal is output to the pilot port 5a or 5b defined according to the operation direction of the operation lever 13a.

  For example, when the operation lever 13a is operated in a direction for operating the traveling motor 2 in the normal rotation direction, the operation device 13 outputs a pilot pressure corresponding to the operation amount of the operation lever 13a to the pilot port 5a. . When the operation lever 13a is operated in a direction to operate the traveling motor 2 in the reverse direction, the operation device 13 outputs a pilot pressure corresponding to the operation amount of the operation lever 13a to the pilot port 5b.

  The hoisting switching valve 6 interposed downstream in the center bypass oil passage 10 is a pilot-driven directional switching valve, like the traveling switching valve 5, and has two pilot ports 6a and 6b. The hoist switching valve 6 has a neutral position B0, a neutral position Ba when a pilot pressure equal to or greater than a predetermined value is applied to the pilot port 6a, and a predetermined value equal to the pilot port 6b. Bb position, which is the operating position when the above pilot pressure is applied.

  The hoist switching valve 6 is connected to two inlet / outlet ports 3a, 3b (inlet or outlet of hydraulic oil) of the hoist motor 3 through two oil passages 21a, 21b as hoist motor oil passages in the present invention. ), And is connected to the hydraulic oil tank 7 via an oil passage 22.

  When no pilot pressure is applied to both of the pilot ports 6a and 6b, the hoisting switching valve 6 is biased so as to be maintained at the neutral position B0. In the B0 position, the hoist switching valve 6 opens the center bypass oil passage 10 on the upstream side to the center bypass oil passage 10 on the downstream side, and further closes both the oil passages 21a and 21b on the hoist motor 3 side. It is configured to be.

  Therefore, at the B0 position (neutral position) of the hoist switching valve 6, the operating oil flowing into the hoist switching valve 6 from the center bypass oil passage 10 on the upstream side of the hoist switching valve 6 is supplied to the hoist motor 3. Instead, it flows into the center bypass oil passage 10 downstream of the hoist switching valve 6.

  When a pilot pressure equal to or more than a predetermined value is applied to the pilot port 6a, the hoist switching valve 6 is displaced from the B0 position (neutral position) to the Ba position with an increase in the pilot pressure. At this Ba position, the hoist switching valve 6 closes the upstream center bypass oil passage 10 with respect to the downstream center bypass oil passage 10 and opens the oil passage 21a on the hoist motor 3 side. The oil passage 21b on the side of the hoist motor 3 is opened to the center bypass oil passage 10 on the downstream side.

  Further, in the process of displacing the hoisting switching valve 6 from the B0 position to the Ba position, the opening of the oil passage (bleed-off oil passage) between the center bypass oil passage 10 on the upstream side and the center bypass oil passage 10 on the downstream side. Becomes gradually smaller as the pilot pressure applied to the pilot port 6a increases, or the opening of the oil passage (meter-in oil passage) between the upstream center bypass oil passage 10 and the oil passage 21a is It is configured to gradually increase as the pilot pressure applied to the port 6a increases.

  Therefore, when the hoisting switching valve 6 is operated to the Ba position side, the operating oil flowing into the hoisting switching valve 6 from the center bypass oil passage 10 on the upstream side of the hoisting switching valve 6 flows from the hoisting switching valve 6 to the oil passage 21a. The hydraulic oil is supplied to the inlet / outlet port 3a of the hoisting motor 3 via the motor, and is discharged from the other inlet / outlet port 3b of the hoisting motor 3 via the oil passage 21b and the hoist switching valve 6 at the Ba position. , And flows into the center bypass oil passage 10 on the downstream side. Further, as the pilot pressure applied to the pilot port 6a increases, the flow rate of the working oil supplied to the inlet / outlet port 3a of the hoist motor 3 increases.

  When a pilot pressure equal to or more than a predetermined value is applied to the pilot port 6b, the hoisting switching valve 6 is displaced from the B0 position (neutral position) to the Bb position as the pilot pressure increases. In this position Bb, the hoist switching valve 6 closes the upstream center bypass oil passage 10 with respect to the downstream center bypass oil passage 10 and opens the center bypass oil passage 10 to the oil passage 21b on the hoist motor 3 side. The oil passage 21a on the side of the hoist motor 3 is opened to the center bypass oil passage 10 on the downstream side.

  Further, in the process of displacing the hoist switching valve 6 from the B0 position to the Bb position, the opening of the oil passage (bleed-off oil passage) between the upstream center bypass oil passage 10 and the downstream center bypass oil passage 10 is performed. Becomes gradually smaller as the pilot pressure applied to the pilot port 6b increases, or the opening of the oil passage (meter-in oil passage) between the upstream center bypass oil passage 10 and the oil passage 21b is It is configured to gradually increase as the pilot pressure applied to the port 6b increases.

  Therefore, when the hoist switching valve 6 is operated to the Bb position side, the operating oil flowing into the hoist switching valve 6 from the center bypass oil passage 10 on the upstream side of the hoist switching valve 6 is transferred from the hoist switching valve 6 to the oil passage 21b. The hydraulic oil is supplied to the inlet / outlet port 3b of the hoisting motor 3 via the motor, and is discharged from the other inlet / outlet port 3a of the hoisting motor 3 via the oil passage 21a and the hoist switching valve 6 at the Bb position. , And flows into the center bypass oil passage 10 on the downstream side. Further, as the pilot pressure applied to the pilot port 6b increases, the flow rate of the working oil supplied to the inlet / outlet port 3b of the hoist motor 3 increases.

  Each of the pilot ports 6a and 6b of the hoist switching valve 6 is connected to an operating device 23 provided with an operating lever 23a for operating the hoist motor 3 via pilot oil passages 24a and 24b, respectively.

  The operating device 23 generates a pilot pressure according to the operation of the operating lever 23a from the primary pressure pilot hydraulic oil supplied from a pilot pump (not shown), similarly to the operating device 13 for the traveling motor 2. The pressure is output to one of the pilot ports 6a and 6b, which is defined according to the operation direction of the operation lever 23a.

  For example, when the operation lever 23a is operated in a direction for operating the hoist motor 3 in the normal rotation direction, the operation device 23 outputs a pilot pressure corresponding to the operation amount of the operation lever 23a to the pilot port 6a. . When the operation lever 23a is operated in a direction to operate the hoist motor 3 in the reverse direction, the operation device 23 outputs a pilot pressure corresponding to the operation amount of the operation lever 23a to the pilot port 6b.

  The hydraulic device 1 according to the present embodiment further includes a counterbalance valve 30 interposed in oil passages 11 a and 11 b between the travel switching valve 5 and the travel motor 2, and a counterbalance valve 30 and the travel motor 2. Two relief valves 33a, 33b interposed in the two oil passages 32a, 32b connecting the oil passages 10a, 10b, respectively, and connected to the oil passages 10a, 10b between the counterbalance valve 30 and the travel switching valve 5. Switching valve 35.

  The counterbalance valve 30 is a pilot-driven switching valve and has two pilot ports 30a and 30b. The counterbalance valve 30 has, as its operation positions, a neutral position C0 position, a Ca position which is an operation position when a pilot pressure equal to or more than a predetermined value is applied to the pilot port 30a, and a predetermined value at the pilot port 30b. And a Cb position which is an operation position when the above pilot pressure is applied.

  Each of the pilot ports 30a and 30b of the counter balance valve 30 is connected to each of the oil passages 11a and 11b via pilot oil passages 31a and 31b. Therefore, the pilot pressure is basically applied to the pilot ports 30 a and 30 b of the counter balance valve 30 according to the operation state of the travel switching valve 5.

  Specifically, when the travel switching valve 5 is held at the A0 position (neutral position), the pilot pressure is not applied to both of the pilot ports 30a and 30b of the counter balance valve 30. In this state, the counterbalance valve 30 is urged to be held at the neutral position C0. In the C0 position, the counterbalance valve 30 functions as a check valve for both the oil passages 11a and 11b, and operates in the direction from the travel switching valve 5 to the travel motor 2 in both the oil passages 11a and 11b. It is configured to allow the flow of oil while preventing the flow of hydraulic oil in the opposite direction.

  Therefore, at the C0 position, the flow of the operating oil in the traveling motor 2 is blocked, and the traveling motor 2 is kept in the operation stop state.

  When the travel switching valve 5 is operated from the A0 position (neutral position) to the Aa position side, the pressure in the oil passage 11a to which the hydraulic oil is supplied from the hydraulic pump 4 becomes higher than the pressure in the oil passage 11b. A pilot pressure higher than the pilot port 30b is applied to the pilot port 30a of the valve 30. In this state, the counterbalance valve 30 operates at the Ca position. At this Ca position, the counterbalance valve 30 is configured to open the oil passage 11b, and functions as a check valve for the oil passage 11a as in the C0 position (neutral position). It is configured.

  Therefore, when the travel switching valve 5 is operated from the A0 position to the Aa position side, the counterbalance valve 30 is operated from the C0 position to the Ca position in conjunction with this operation. Eventually, the traveling motor 2 operates while the supply of hydraulic oil to the inlet / outlet port 2a of the traveling motor 2 and the discharge of hydraulic oil from the inlet / outlet port 2b are performed.

  When the travel switching valve 5 is operated from the A0 position (neutral position) to the Ab position, the pressure in the oil passage 11b to which the hydraulic oil is supplied from the hydraulic pump 4 becomes higher than the pressure in the oil passage 11a. The pilot port 30b of the valve 30 is in a state where a pilot pressure higher than that of the pilot port 30a is applied. In this state, the counterbalance valve 30 operates at the Cb position. In the Cb position, the counterbalance valve 30 is configured to open the oil passage 11a, and functions as a check valve for the oil passage 11b as in the C0 position (neutral position). It is configured.

  Therefore, when the travel switching valve 5 is operated from the A0 position to the Ab position, the counterbalance valve 30 is operated from the C0 position to the Cb position in conjunction with the operation. Eventually, the traveling motor 2 operates while the supply of hydraulic oil to the inlet / outlet port 2b of the traveling motor 2 and the discharge of hydraulic oil from the inlet / outlet port 2a are performed.

  The relief valves 33a and 33b are for generating a brake pressure when the operation of the traveling motor 2 is released (when the traveling drive of the crawler 51a of the lower traveling body 51 is released by the traveling motor 2). In this case, when the operation position of the travel switching valve 5 returns from the Aa position to the A0 position and the counterbalance valve 30 returns from the Ca position to the C0 position, the relief valve 33b provides an input / output port for the travel motor 2. When the pressure of the hydraulic oil on the 2b side (the hydraulic oil discharged from the traveling motor 2) becomes higher than the pressure of the hydraulic oil on the inlet / outlet port 2a by a predetermined pressure or more, the oil passage 32b is opened ( Consequently, the operating oil is recirculated from the input / output port 2b of the traveling motor 2 to the input / output port 2a via the oil passage 32b).

  Also, the relief valve 33a is used to move the travel switching valve 5 from the Ab position side to the A0 position and return the counterbalance valve 30 from the Cb position to the C0 position. The oil passage 32a is opened when the pressure of the hydraulic oil on the side (the hydraulic oil discharged from the traveling motor 2) becomes higher than the pressure of the hydraulic oil on the side of the inlet / outlet port 2b by a predetermined pressure or more. The operating oil is recirculated from the input / output port 2a of the traveling motor 2 to the input / output port 2b via the oil passage 32a).

  The switching valve 35 is a pilot-driven switching valve disposed at both ends in oil passages 36 connected to the oil passages 11a and 11b (two traveling motor oil passages), respectively. 35b. The switching valve 35 has, as its operation positions, a neutral position D0 position, an operation position Da when the pilot pressure equal to or higher than a predetermined value is applied to the pilot port 35a, and a predetermined value equal to or higher than the pilot port 35b. And Db position, which is an operation position when the pilot pressure is applied. The D0 position (neutral position) is an operating position for closing the oil passage 36 through which the operating oil can flow from one of the oil passages 11a and 11b to the other via the switching valve 35, and is the first state in the present invention. Is equivalent to Further, both the Da position and the Db position are operating positions for opening the oil passage 36, and correspond to the second state in the present invention.

  In the course of the displacement from the D0 position to the Da position or the Db position, the switching valve 35 gradually increases the opening of the oil passage 36 as the pilot pressure applied to the pilot port 35a or 35b increases. It is configured.

  The pilot port 35a of the switching valve 35 is connected to an oil passage 21a connected to one of the inlet / outlet ports 3a of the hoist motor 3 and a pilot oil having a passage portion in which a check valve 37a and a throttle portion 38a are connected in parallel. They are connected via a passage 39a. In this case, the check valve 37a is configured to allow the flow of the pilot hydraulic oil in the direction from the oil passage 21a toward the pilot port 35a and to block the flow of the pilot hydraulic oil in the reverse direction.

  The pilot port 35b of the switching valve 35 is a pilot oil having a passage portion in which a check valve 37b and a throttle portion 38b are connected in parallel to an oil passage 21b connected to the other inlet / outlet port 3b of the hoist motor 3. They are connected via a passage 39b. In this case, the check valve 37b is configured to allow the flow of the pilot hydraulic oil in the direction from the oil passage 21b toward the pilot port 35b, and to block the flow of the pilot hydraulic oil in the reverse direction.

  Therefore, when the pressure of the hydraulic oil flowing into the inlet / outlet port 3a or 3b of the hoisting motor 3 becomes larger than a predetermined value during the operation of the hoisting motor 3 (when the operating oil is supplied to the inlet / outlet port 3a or 3b of the hoisting motor 3). A predetermined one of the oil passages 21a and 21b connected to the hoist motor 3 from the oil passage 21a or 21b on the side supplying hydraulic oil to the hoist motor 3 through the pilot oil passage 39a or 39b to the pilot port 35a or 35b. A pilot pressure equal to or greater than the value is applied. As a result, the switching valve 35 is operated from the D0 position (neutral position) to the Da position side or the Db position side, and thus the oil passages 11a and 11b are operated to the Da position side or the Db position side and the oil passage. 36.

  Since the hydraulic device 1 of the present embodiment is configured as described above, the following effects can be obtained. For example, in order to move the load suspended on the hook 59, the hoist switching valve 6 is operated to the Ba position side or the Bb position side by operating the operation lever 23a of the operation device 23, and the hydraulic pump 4 is used to move the center bypass oil passage. When the operating oil is supplied to the hoist motor 3 via the hoist switching valve 6 and the hoist switching valve 6, the travel switching valve 5 is moved to the A0 position (neutral) by operating the operation lever 13 a of the operating device 13 to operate the traveling motor 2. Position) to the Aa position side or the Ab position side.

  In this case, the counterbalance valve 30 is operated from the C0 position to the Ca position side or the Cb position side in conjunction with the operation of the travel switching valve 5, so that the hydraulic pump 4 allows the travel switching valve 5 and the oil passages 11a and 11b to communicate with each other. Hydraulic oil of the travel motor 2 is supplied via one of the oil passages, and hydraulic oil discharged from the travel motor 2 is further supplied to the other of the oil passages 11a and 11b, the travel switching valve 5, and the downstream side thereof. The power is supplied to the hoist motor 3 via the center bypass oil passage 10 and the hoist switching valve 6.

  Here, the load suspended on the hook 59 is often heavy, so that the load on the hoist motor 3 is often quite large. In such a case, of the oil passages 11a and 11b, the oil passage 11a or 11b on the discharge side (return side of hydraulic oil) of the traveling motor 2 is connected to the oil passage 21a or the hydraulic oil supply side of the hoist motor 3. If the switching valve 35 and the oil passage 36 are not provided, the pressure in the oil passage 11a or 11b on the discharge side of the traveling motor 2 increases to a large pressure and the supply side of the traveling motor 2 The pressure in the oil passage 11b or 11a increases to a pressure higher than the pressure in the discharge-side oil passage 11a or 11b.

  Eventually, a high pressure acts on both the inlet / outlet ports 2a and 2b of the traveling motor 2 and there is a possibility that troubles such as damage to the cylinder block of the traveling motor 2 may occur.

  However, in the present embodiment, when the pressure in the oil passage 21a or 21b on the supply side of the working oil of the hoist motor 3 becomes larger than a predetermined value, the pilot oil passage 39a or 39b is transferred from the oil passage 21a or 21b on the supply side. The switching valve 35 is actuated to the Da position side or the Da position side by the pilot pressure applied to the pilot port 35a or 35b of the switching valve 35 via.

  Eventually, the oil passages 11 a and 11 b between the travel switching valve 5 and the counterbalance valve 30 communicate with each other via the oil passage 36 and the switching valve 35. For this reason, the hydraulic oil supplied from the hydraulic pump 4 to the oil passage 11 a or 11 b via the travel switching valve 5 is not supplied to the traveling motor 2, but from the oil passage 11 a or 11 b to the oil passage 36, The oil is supplied to the hoist motor 3 via the return-side oil passage 11 b or 11 a, the travel switching valve 5, the center bypass oil passage 10 on the downstream side thereof, and the hoist switching valve 6.

  For this reason, the high pressure is prevented from acting on both of the inlet / outlet ports 2a and 2b of the traveling motor 2, thereby preventing the traveling motor 2 from being damaged or the like. In this case, the oil passages 11a and 11b between the travel switching valve 5 and the counterbalance valve 30 communicate with each other via the oil passage 36 and the switching valve 35, so that the pressure difference between the oil passages 11a and 11b is eliminated. Therefore, the counterbalance valve 30 automatically returns to the C0 position (neutral position). Therefore, the traveling motor 2 is kept in the operation stop state. Therefore, when the load on the hoist motor 3 is large, the operation of the traveling motor 2 is substantially prohibited.

  In addition, when the load on the hoist motor 3 is reduced due to, for example, release of suspension of the conveyed object from the hook 59, the switching valve 35 returns to the D0 position (neutral position). In this return operation, the operating oil is discharged from the pilot port 35a or 35b of the switching valve 35 to which the high pilot pressure has been applied through the throttle portion 38a or 38b, so that the pilot pressure gradually decreases. . As a result, the switching valve 35 gradually returns from the Da position or the Db position to the D0 position (neutral position).

  For this reason, when the load on the hoist motor 3 is reduced, even if the travel switching valve 5 is operated to the Aa position side or the Ab position side by the operation of the operation lever 13 a of the operation device 13, the drive motor 2 An abrupt increase in the supply amount of the hydraulic oil (accordingly, an abrupt start of the operation of the traveling motor 2) is prevented.

  It should be noted that the present invention is not limited to the embodiment described above, and other embodiments can be adopted. Hereinafter, some other embodiments will be described.

  In the above embodiment, the switching valve 35 having three operating positions D0, Da, and Db is used as the switching valve 35 between the oil passages 11a and 11b. For example, a set of the Da position and the pilot port 35a or the Db position It is also possible to use a switching valve (a switching valve having two operation positions) in which the set of the pilot port 35b is omitted, instead of the switching valve 35. In this case, pilot pressure may be applied to the pilot port for operating the switching valve from the neutral position (closed position) to the open position via the shuttle valves from the oil passages 21a and 21b.

  Further, instead of operating the switching valve 35 using the pressure of the oil passages 21a and 21b as a pilot pressure, for example, a pressure sensor for detecting the pressure of the oil passages 21a and 21b is provided, and in accordance with a detection value of the pressure sensor. It is also possible to operate the switching valve 35 via a proportional valve or the like.

  In the above-described embodiment, the check valves 37a and 37b and the throttle portions 38a and 38b connected in parallel are interposed in the pilot oil passages 39a and 39b for the switching valve 35, respectively. The apertures 37a and 37b and the apertures 38a and 38b may be omitted.

  In the above-described embodiment, the hoisting device 56 is a device for moving the hook 59 via the wire 58. However, the hoisting device according to the present invention performs, for example, an up / down operation of the boom 54 (jib) via the wire. It may be a device that makes the device work.

  Further, the hydraulic device 1 of the embodiment has the counterbalance valve 30 and the relief valves 33a and 33b in the hydraulic circuit for the traveling motor 2. However, the hydraulic device of the present invention includes the counterbalance valve 30 and the relief valve. One or both of the valves 33a and 33b may not be provided.

  The construction machine 50 of the embodiment is a mobile crane having the structure shown in FIG. 1, but the construction machine according to the present invention includes a hoist for moving a hook and a hoist for moving a boom (jib). May be done. Further, the construction machine may be a construction machine other than the mobile crane.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic device, 2 ... Traveling motor, 3 ... Hoisting motor, 4 ... Hydraulic pump, 5 ... Traveling switching valve, 6 ... Lifting switching valve, 11a, 11b ... Oil passage (oil passage for traveling motor), 21a, 21b ... Oil passages (oil passages for hoisting motor), 35: switching valves, 37a, 37b: check valves, 38a, 38b: throttle portions, 39a, 39b: pilot oil passages.

Claims (3)

A traveling motor that is a traveling hydraulic motor, a hoisting motor that is a hydraulic motor for driving a hoisting device, a hydraulic pump that discharges hydraulic oil, and a traveling switching valve that is a direction switching valve connected to the traveling motor. A hoist switching valve that is a directional switching valve connected to the hoist motor, wherein the travel switching valve is configured such that the operating oil discharged from the hydraulic pump flows upstream of the hoist switching valve. The hoisting switching valve is connected to the hydraulic pump, and when the operation oil of the traveling motor is stopped, the hydraulic oil discharged from the hydraulic switching valve flows in through the traveling switching valve, and the traveling motor A hydraulic device for a construction machine connected to the travel switching valve so as to flow in through the travel switching valve and the travel motor when the is operated,
A first state in which the two traveling motor oil passages are connected to each other so that hydraulic oil flows between the traveling switching valve and the traveling motor and the two traveling motor oil passages are communicated with each other; A switching valve operable in a second state, wherein when the pressure of the hydraulic oil supplied from the hoisting switching valve to the hoisting motor becomes a high pressure equal to or higher than a predetermined value, the switching valve A hydraulic device for a construction machine, wherein the hydraulic device is configured to operate according to the pressure so as to switch from the second state to the first state. The hydraulic device for a construction machine according to claim 1,
The hoist switching valve is provided with two hoists for flowing hydraulic oil between the hoist switching valve and the hoist motor so that the pressure of the hydraulic oil supplied from the hoist switch valve to the hoist motor is applied as pilot pressure. A hydraulic device for a construction machine, which is a pilot-driven switching valve connected to a motor oil passage via a pilot oil passage. The hydraulic device for a construction machine according to claim 2,
The pilot oil passage is provided with a check valve and a throttle connected in parallel with each other, and the check valve is arranged in a direction opposite to the direction from the hoist motor oil passage to the switching valve. A hydraulic device for a construction machine, wherein the hydraulic device is configured to block a flow of hydraulic oil.