Hydraulic control device

Abstract

The present invention provides an oil pressure control device in which a neutral position, a first function position, and a second function position are arranged in the order listed, wherein an action corresponding to the second function position can be performed without causing an action corresponding to the first function position to be performed from the neutral position. The oil pressure control device is provided with an electromagnetic proportional valve PV used for a switching action of a switching control valve (26, 32), a control unit that controls the functioning of the electromagnetic proportional valve PV on the basis of an operation command for an operating tool, and a mode-switching means capable of switching a control mode. The operating tool can be operated to one side area, a neutral area, and another side area. When the operating tool is operated to the other side area in the first mode, the control unit supplies an electric current value corresponding to an other-side first function position (Ph, Dw) to the electromagnetic proportional valve PV, and when the operating tool is operated to the other side area in the second mode, the control unit supplies an electric current value corresponding to an other-side second function position (Pd, Fr) to the electromagnetic proportional valve PV.

Description

[Technical Field]

[0001] The present invention relates to a hydraulic control device used in, for example, a work vehicle or the like, for controlling the supply and discharge of hydraulic oil. [Background technology]

[0002] An example of a work vehicle equipped with the above-mentioned hydraulic control device is a tractor body equipped with a front loader. In the hydraulic control device used in this type of work vehicle, a bucket is swingably attached to a boom, and the hydraulic control device is equipped with a hydraulic cylinder that swings the bucket, a switching control valve that controls the hydraulic cylinder, and an operating tool that manually switches the switching control valve (see, for example, Patent Document 1).

[0003] In Patent Document 1, the switching control valve is configured to be operable to a rollback position that enables the bucket to scoop up soil and sand, a neutral position that does not supply or discharge hydraulic oil to the hydraulic cylinder, a rapid operation position that rapidly operates the bucket to quickly release soil and sand, and a standard speed position that operates the bucket to release soil and sand at a standard speed.

[0004] The hydraulic control device described in Patent Document 1 has a rollback position (one-side operating position), a neutral position, a rapid operating position (the other-side first operating position), and a standard speed position (the other-side second operating position) arranged in this order. Therefore, to release earth and sand from the bucket, the bucket can be rapidly operated by operating the operating tool from the neutral position to the rapid operating position. Thereafter, the operating tool can be further operated to the standard speed position, allowing the bucket to operate at the standard speed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-285564 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the above-described conventional configuration, even when directly operating from the neutral position to the other-side second operating position, the intended operation may not be achieved because the other-side first operating position must be passed through the other-side first operating position. For example, in the case of Patent Document 1, when an operating tool in the neutral position is operated to release soil or sand from the bucket, the bucket cylinder always operates rapidly, making it difficult to operate the operating tool when releasing soil or sand at a standard speed. Furthermore, in Patent Document 1, the other-side first operating position is assigned as a rapid operating position, and the other-side first operating position is assigned as a standard speed position. However, even when other operations are assigned to the other-side first operating position and the other-side second operating position, there may be cases where an operation corresponding to the other-side second operating position is desired without performing the operation of the other-side first operating position. Furthermore, for example, when replacing the bucket with another implement, the other-side first position is not necessary, and it may be desirable to be able to switch directly from the neutral position to the other-side second position.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to enable a hydraulic control device in which a neutral position, a first operating position, and a second operating position are arranged in this order to perform an operation corresponding to the second operating position without performing an operation corresponding to the first operating position from the neutral position. [Means for solving the problem]

[0008] A characteristic configuration of a hydraulic control device according to the present invention includes a switching control valve that switches the supply and discharge state of hydraulic oil, an electromagnetic proportional valve for switching the switching control valve, a control unit that controls the operation of the electromagnetic proportional valve based on an operation command from an operating tool, and mode switching means that can switch the control mode of the control unit between a first mode and a second mode, and the operating tool can be operated to one side region, a neutral region, and an other side region, and the switching control valve is before Operating tools From the neutral zonea one-side operating position that is switched in response to an operation to the one-side region, a neutral position that is switched when the operating tool is not operated, and From the neutral zone a first operating position on the other side that is switched when the operating tool is operated to the other side region; From the neutral zone The switch is performed when the operation is performed to the other side area. Other side first operating position and a second operating position on the other side different from the first operating position, the switching control valve is arranged in the one-side operating position, the neutral position, the other-side first operating position, and the other-side second operating position in this order, The control unit is configured to supply, in the first mode, a current value corresponding to the other-side first operating position to the electromagnetic proportional valve when the operating tool is operated from the neutral position to the other-side region, and to supply, in the second mode, a current value corresponding to the other-side second operating position to the electromagnetic proportional valve when the operating tool is operated from the neutral position to the other-side region.

[0009] According to the present invention, when the first mode is set by the mode switching device, operating the operating device from the neutral position to the other-side region causes the electromagnetic proportional valve to operate and switch the switching control valve to the other-side first operating position. On the other hand, when the second mode is set by the mode switching device, operating the operating device from the neutral position to the other-side region causes the electromagnetic proportional valve to operate and switch the switching control valve to the other-side second operating position. That is, in the first mode, the switching control valve can be switched to three positions, one-side operating position, neutral position, and other-side first operating position, based on the operation of the operating device, and in the second mode, the switching control valve can be switched to three positions, one-side operating position, neutral position, and other-side second operating position, based on the operation of the operating device.

[0010] In this way, by switching the operating mode using the mode switching means and changing the current value to the electromagnetic proportional valve, the supply and discharge state of the hydraulic oil can be switched between different states. Therefore, in a hydraulic control device in which the neutral position, the other-side first operating position, and the other-side second operating position are arranged in this order, it is possible to perform an operation corresponding to the other-side second operating position from the neutral position without performing an operation corresponding to the other-side first operating position.

[0011] In the present invention, the switching control valve switches a supply / discharge state of hydraulic oil from a hydraulic pump to a hydraulic actuator, and in the one-side operating position, the switching control valve switches to a supply / discharge state for operating the hydraulic actuator in a first operating direction, The aforementioned At the other side first operating position, the hydraulic actuator is switched to a supply / discharge state for operating in a first operating state in a second operating direction; The aforementioned In the other side second operating position, the hydraulic actuator is moved in a second operating direction in a direction different from the first operating state. two It may be configured to switch to a supply / discharge state for operation in the operating state.

[0012] According to this configuration, for example, in order to switch the operating state of the hydraulic actuator between a first operating state and a second operating state when the operating tool is operated from the neutral region to the other side region, a complex configuration such as separately providing a dedicated flow path switching control valve or an opening / closing valve in addition to the switching control valve is not required, and there is little risk of the configuration becoming complicated.

[0013] Therefore, it is possible to easily switch the operating state of the hydraulic actuator without complicating the configuration.

[0014] In the present invention, it is preferable that the hydraulic actuator is a hydraulic cylinder, the first operating state is a high-speed operating state in which the hydraulic cylinder is operated at high speed, and the second operating state is a low-speed operating state in which the hydraulic cylinder is operated at low speed.

[0015] According to this configuration, in the first mode, operating the operating tool from the neutral region to the other-side region can operate the hydraulic cylinder at high speed, while in the second mode, operating the operating tool from the neutral region to the other-side region can operate the hydraulic cylinder at low speed.

[0016] As a result, for example, when applied to a configuration in which a hydraulic cylinder swings a bucket, an appropriate working mode can be selected depending on the working situation, such as a working mode that quickly releases soil and sand from the bucket, or a working mode that releases it at a standard speed, thereby improving usability.

[0017] In the present invention, the hydraulic cylinder is configured as a double-acting type, and the switching control valve is configured as the other side first one It is preferable that when the hydraulic cylinder is switched to the operating position, return oil from the hydraulic cylinder merges with pressure oil supplied to the hydraulic cylinder.

[0018] According to this configuration, by effectively utilizing the return oil from the hydraulic cylinder, the operating state of the hydraulic cylinder can be switched between the first operating state and the second operating state with a simple configuration.

[0019] In the present invention, the hydraulic actuator is a hydraulic cylinder, and at the one side operating position, the hydraulic oil from the hydraulic pump is supplied to the hydraulic cylinder. The aforementioned a first port for actuation in a first direction of movement; The aforementioned At the other side first operating position, hydraulic oil from the hydraulic pump is supplied to a second port of the hydraulic cylinder for operating the hydraulic cylinder in a second operating direction, The aforementioned In the other side second operating position, the supply of hydraulic oil from the hydraulic pump to the first port and the second port may be blocked, and the first port may be connected to the second port to connect to a drain oil passage that discharges the hydraulic oil to a tank.

[0020] According to this configuration, by operating the operating tool from the neutral region to the other-side region in the second mode, both ports of the hydraulic cylinder can be connected to the drain oil passages to bring the hydraulic cylinder into a floating state.

[0021] In the present invention, the switching control valve is configured to switch the operating position by sliding a spool with a hydraulic pilot operating pressure, and the solenoid proportional valve is configured to have a one-side valve that can change the pilot operating pressure for sliding the spool to one side. The aforementioned a solenoid proportional valve and a variable pilot operating pressure for sliding the spool to the other side; The aforementioned Preferably, a proportional solenoid valve is provided.

[0022] According to this configuration, the switching control valve slides the spool using hydraulic pilot operating pressure, so even if the sliding stroke amount is large, the switching operation can be performed smoothly with a strong hydraulic operating force.

[0023] In the present invention, it is preferable that the operating tool is configured as an operating lever that can be operated by swinging, and the mode switching means is configured as a switch that is provided on the grip portion of the operating tool and can be operated by a finger.

[0024] With this configuration, the operator can change the control mode by operating the switch with his / her fingers while gripping and operating the operating lever, which eliminates the hassle of having to move his / her hand and provides excellent operability.

[0025] In the present invention, it is preferable that the other-side region of the operating tool is set to an other-side first region located on the neutral region side and an other-side second region located on the opposite side of the neutral region, the mode switching means is configured to be switchable to a third mode, and the control unit is configured, in the third mode, to supply to the electromagnetic proportional valve a current value corresponding to the other-side first operating position when the operating tool is operated to the other-side first region, and to supply to the electromagnetic proportional valve a current value corresponding to the other-side second operating position when the operating tool is operated to the other-side second region.

[0026] According to this configuration, if the third mode is set by the mode switching means, when the operating tool is operated to the other-side first region, the switching control valve is switched to the other-side first operating position. Furthermore, when the operating tool is operated from the other-side first region to the other-side second region, the switching control valve is switched from the other-side first operating position to the other-side second operating position.

[0027] That is, in the first and second modes, the switching control valve can be switched to three positions based on the operation of the operating device, whereas in the third mode, the switching control valve can be switched to four positions, namely, one-side operating position, neutral position, other-side first operating position, and other-side second operating position, based on the operation of the operating device.

[0028] Therefore, the switching control valve can be switched between a three-position switching state and a four-position switching state for selective use, improving convenience. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a side view of a tractor equipped with a front loader. [Figure 2] FIG. 2 is a hydraulic circuit diagram of a hydraulic control unit. [Figure 3] FIG. 2 is a diagram showing an operating lever and a control configuration. [Figure 4] FIG. 2 is a perspective view showing a grip portion of an operating lever. [Figure 5] FIG. 10 is a diagram showing the change characteristics of the lever operation angle and the current value. [Figure 6] 10A and 10B are diagrams illustrating an operating lever and a control configuration according to another embodiment. [Figure 7] FIG. 10 is a diagram showing the change characteristics of the lever operation angle and the current value in another embodiment. [Figure 8] FIG. 10 is a diagram showing the change characteristics of the lever operation angle and the current value in another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a tractor A as an example of a work vehicle equipped with a front loader 10. In the figure, the front of the tractor is indicated by "F" and the rear is indicated by "R".

[0031] Tractor A has an engine 4 at the front of a body 3 having front wheels 1 and rear wheels 2, and houses a driver's seat 6 and a steering wheel 7 at the rear of the body 3 inside a cabin 5 that covers the driver's section.

[0032] The front loader 10 comprises left and right pillar-like frames 11, left and right booms 12, one bucket 13, left and right boom hydraulic cylinders 14 (hereinafter referred to as boom cylinders) as hydraulic actuators, and a bucket hydraulic cylinder 15 (hereinafter referred to as bucket cylinder) as a hydraulic actuator. By removably attaching the left and right pillar-like frames 11 to the vehicle body 3, the entire front loader 10 can be attached and detached to and from the vehicle body 3.

[0033] The front ends of the left and right booms 12 protrude forward of the vehicle body 3, and their base ends are supported at the upper ends of the corresponding left and right support frames 11 so that the front ends can move up and down. Furthermore, a bucket 13 is supported at the front ends of the left and right booms 12 so that it can swing up and down around a horizontally oriented support shaft 13a.

[0034] The boom cylinder 14 is a double-acting type, with a boom-side piston rod 14a connected to the column-like frame 11 and the bottom of the boom-side cylinder portion 14b connected to the boom 12. The bucket cylinder 15 is a double-acting type, with a bucket-side piston rod 15a connected to the bucket 13 and a boom-side cylinder portion 15b of the bucket cylinder 15 connected to the boom 12.

[0035] With this configuration, the front loader 10 raises the tip of the boom 12 by extending the boom cylinder 14, and lowers the tip of the boom 12 by retracting the boom cylinder 14. The front loader 10 also performs a dumping operation by swinging the bucket 13 downward about the support shaft 13a by extending the bucket cylinder 15, and performs a scooping operation by swinging the bucket 13 upward about the support shaft 13a by retracting the bucket cylinder 15.

[0036] As shown in Fig. 1, an operating lever 16 as an example of an operating tool is provided near the driver's seat 6. In the front loader 10, operation of the operating lever 16 enables the extension and retraction of the boom cylinder 14 and the bucket cylinder 15. As shown in Fig. 4, the operating lever 16 is configured to be operable in Y and Z directions that are perpendicular to each other in a plan view, and operating the operating lever 16 in the Y direction controls the bucket 13, and operating the operating lever in the Z direction controls the boom 12.

[0037] 3, by swinging the operating lever 16 in the Y direction, it can be switched between a scooping area E as one side area where the bucket 13 performs a scooping operation, a neutral area N where the operation of the bucket cylinder 15 is stopped, and a dumping area F as the other side area where the bucket 13 is dumped. In addition, by swinging the operating lever 16 in the Z direction, it can be switched between one side area where the boom 12 is raised, the neutral area N where the operation of the boom 12 is stopped, and the other side area where the boom 12 is lowered.

[0038] 2, there is provided a hydraulic control unit 20 that controls the operation of the boom cylinder 14 and the bucket cylinder 15. The hydraulic control unit 20 is provided with a hydraulic oil flow path 22 to which hydraulic oil is supplied from a hydraulic pump 21 driven by the engine 4, a drain oil path 23 that discharges the hydraulic oil to a tank, a boom control unit 24 that switches the operating state of the boom cylinder 14, and a bucket control unit 25 that switches the operating state of the bucket cylinder 15.

[0039] Boom control section 24 is provided with boom control valve 26 as a switching control valve that supplies and discharges hydraulic oil supplied through hydraulic oil passage 22 to boom cylinder 14, and a pair of electromagnetic proportional valves PV for switching operation of boom control valve 26. Also provided are a first passage 28 that supplies hydraulic oil from boom control valve 26 to one cylinder chamber that extends boom cylinder 14, a second passage 29 that supplies hydraulic oil from boom control valve 26 to the other cylinder chamber that retracts boom cylinder 14, a pilot-operated check valve 30 interposed in first passage 28, a relief valve 31 for adjusting pressure, and the like.

[0040] The bucket control section 25 is provided with a bucket control valve 32 as a switching control valve that supplies and discharges hydraulic oil supplied through the hydraulic oil passage 22 to the bucket cylinder 15, and a pair of electromagnetic proportional valves PV for switching the bucket control valve 32. Also provided are a third passage 34 that supplies hydraulic oil from the bucket control valve 32 to one cylinder chamber that extends the bucket cylinder 15, a fourth passage 35 that supplies hydraulic oil from the bucket control valve 32 to the other cylinder chamber that contracts the bucket cylinder 15, a pilot-operated check valve 36 interposed in the fourth passage 35, and a relief valve 37 for adjusting pressure.

[0041] The boom control valve 26 is a four-position control valve that can be switched, in that order, as control switching positions among an up position Up as one side operating position, a neutral position N, a down position Dw as the other side first operating position, and a floating position Fr as the other side second operating position. In the up position Up, the hydraulic oil passage 22 and the first passage 28 are connected, and hydraulic oil from the hydraulic pump 21 is supplied to the first port for raising of the boom cylinder 14. This causes the boom 12 to operate in the up direction ('first operating direction'). At this time, the second passage 29 is connected to the discharge port. In the neutral position N, the hydraulic oil passage 22 is blocked from communication with the first passage 28 and the second passage 29, and the hydraulic oil passage 22 is connected to the downstream side (discharge side). In the down position Dw, the hydraulic oil passage 22 is connected to the second passage 29, and hydraulic oil from the hydraulic pump 21 is supplied to the second port for lowering of the boom cylinder 14. As a result, the boom 12 operates in the downward direction (second operating direction). At this time, the first flow path 28 is connected to the discharge port. Furthermore, in the lowered position Dw, pilot operating pressure is applied to the check valve 30 interposed in the first flow path 28, allowing the hydraulic oil to be discharged. In the floating position Fr, the hydraulic oil flow path 22 is blocked from communication with the first flow path 28 and the second flow path 29, and the first flow path 28 is connected to the second flow path 29, and further the first flow path 28 and the second flow path 29 are connected to the drain oil path 23.

[0042] The bucket control valve 32 is a four-position switching control valve that can be switched in that order between a scooping position Ps as one operating position, a neutral position Pn, a quick dump position Ph as the other first operating position, and a standard dump position Pd as the other second operating position. At the scooping position Ps, the hydraulic oil passage 22 is connected to the fourth passage 35, and the drain oil passage 23 is connected to the third passage 34. When the bucket control valve 32 is switched to the scooping position Ps, the bucket cylinder 15 operates to the scooping side, which is one side of the extension / retraction direction. At the neutral position Pn, the hydraulic oil passage 22 is blocked from the third passage 34 and the fourth passage 35, and the hydraulic oil passage 22 is connected to the downstream side. At this time, the operation of the bucket cylinder 15 is stopped.

[0043] At the quick dump position Ph, the hydraulic oil flow path 22 and the third flow path 34 are connected to each other, and the oil discharged from the fourth flow path 35 also merges with the third flow path 34. When the bucket control valve 32 is switched to the quick dump position, the bucket cylinder 15 is operated in a high-speed operating state as a first operating state toward the dump operating side, which is the other side of the extension / contraction direction.

[0044] At the standard dump position Pd, the hydraulic oil passage 22 and the third passage 34 are connected to each other, and the drain oil passage 23 and the fourth passage 35 are connected to each other. That is, the oil discharged from the fourth passage 35 is discharged to the tank side. When the bucket control valve 32 is switched to the standard dump position, the bucket cylinder 15 is operated in a low-speed operating state as a second operating state toward the dump operating side.

[0045] At the quick dump position Ph and the standard dump position Pd, a pilot operating pressure is applied to a check valve 36 interposed in the fourth flow path 35 to enable the hydraulic oil to be discharged from the other cylinder chamber of the bucket cylinder 15 .

[0046] The high-speed operating state is used in an operation in which the bucket 13 is dumped at a high speed to facilitate the discharge of loads that are difficult to separate, such as earth and sand. In contrast, the low-speed operating state is used in an operation in which the bucket 13 is dumped at a low speed to slowly discharge the load scooped up by the bucket 13 downward.

[0047] The boom control valve 26 is configured to switch its operating position by sliding a spool using hydraulic pilot operating pressure. The pilot pressure is controlled by each of a pair of electromagnetic proportional valves PV, and the spool of the boom control valve 26 is shifted by this pilot pressure to switch it to each of the operating positions.

[0048] Like the boom control valve 26, the bucket control valve 32 is configured to switch its operating position by sliding a spool using hydraulic pilot operating pressure controlled by operating an electromagnetic proportional valve. The electromagnetic proportional valves PV include a one-side electromagnetic proportional valve PV1 that can change the pilot operating pressure for sliding the spool to one side, and a other-side electromagnetic proportional valve PV2 that can change the pilot operating pressure for sliding the spool to the other side. The pair of electromagnetic proportional valves PV controls pilot pressure, and the spool of the bucket control valve 32 is shifted using this pilot pressure to switch it to each of the operating positions. The electromagnetic proportional valves PV are configured to be operated using hydraulic oil from a pilot hydraulic pump 38.

[0049] When the operating lever 16 is in the neutral region N, the control unit 41 operates the spool of the bucket control valve 32 to the neutral position Pn. Furthermore, when the operating lever 16 is in the scooping region E, the control unit 41 supplies a current value corresponding to the scooping position Ps to the target electromagnetic proportional valve PV1. This switches the spool of the bucket control valve 32 to the scooping position Ps.

[0050] The control unit 41 is configured to be able to switch between a first mode and a second mode, which are different control operations when the operating lever 16 is operated to the dump area F.

[0051] A mode selector switch 42 is provided as mode switching means that can switch the control mode of the control unit 41 between a first mode and a second mode. As shown in Fig. 4, the mode selector switch 42 is provided on the side of the grip portion 16a of the operating lever 16 so as to be operable by the fingers of the hand that grips and operates the grip portion 16a. By repeatedly pressing the mode selector switch 42, the control mode of the control unit 41 can be switched between the first mode and the second mode.

[0052] In the first mode, the control unit 41 is configured to supply a current value corresponding to the quick dump position Ph to the target solenoid proportional valve PV2 when the control lever 16 is operated from the neutral region N to the dump region F. In the second mode, the control unit 41 is configured to supply a current value corresponding to the standard dump position to the solenoid proportional valve PV2 when the control lever 16 is operated from the neutral region N to the dump region F.

[0053] FIG. 5 shows the change in the value of the current supplied to the solenoid proportional valve PV relative to the change in the lever tilt angle when the operating lever 16 is operated from the neutral region N to the dump region F along the Y direction. In FIG. 5, line L1 indicates the change characteristic corresponding to the first mode, and line L2 indicates the change characteristic corresponding to the second mode.

[0054] In the first mode, as shown by line L1, when the operating lever 16 is in the neutral region N, the control unit 41 supplies zero current to the electromagnetic proportional valve PV, and the spool of the bucket control valve 32 is urged back to the neutral position Pn by a urging spring (not shown). When the operating lever 16 is operated to the dump region, the control unit 41 supplies to the electromagnetic proportional valve PV2 a current of a value necessary to switch the bucket control valve 32 to the quick dump position Ph. The current supplied is such that the current value gradually increases as the operating lever 16 is operated gradually within the dump region F in a direction away from the neutral position. In other words, the bucket cylinder 15 performs a dump operation at a gradually increasing speed as the lever tilt angle increases.

[0055] In the second mode, as shown by line L2, when the operating lever 16 is in the neutral region N, the control unit 41 supplies zero current to the electromagnetic proportional valve PV, and when the operating lever 16 is operated to the dump region F, supplies to the electromagnetic proportional valve PV2 a current of a value necessary to switch the bucket control valve 32 to the standard dump position Pd. The current supplied is such that the current value gradually increases as the operating lever 16 is operated sequentially within the dump region F in a direction away from the neutral position n. In other words, the bucket cylinder 15 performs a dump operation at a gradually increasing speed as the lever tilt angle increases.

[0056] When the operating lever 16 is in the neutral region N, the control unit 41 operates the spool of the boom control valve 26 to the neutral position N. Furthermore, when the operating lever 16 is in one side region for raising the boom 12, the control unit 41 supplies a current value corresponding to the boom raising operation to the target solenoid proportional valve PV1. This switches the spool of the boom control valve 26 to the raised position.

[0057] The control unit 41 is configured to be switchable between a first mode and a second mode, which are different control operations when the operating lever 16 is operated to the other side region where the boom 12 is lowered. A boom operation mode selector switch (not shown) is provided as mode selector means that can switch the control mode of the control unit 41 between a first mode and a second mode. The boom operation mode selector switch may be common to the mode selector switch 42, or may be provided separately. By repeatedly pressing the boom operation mode selector switch, the control mode of the control unit 41 can be switched between the first mode and the second mode.

[0058] In the first mode, the control unit 41 is configured to supply a current value corresponding to a boom lowering operation to the target solenoid proportional valve PV2 when the control lever 16 is operated from the neutral region N to the other side region. In the second mode, the control unit 41 is configured to supply a current value corresponding to a floating position to the solenoid proportional valve PV2 when the control lever 16 is operated from the neutral region N to the other side region.

[0059] The change in the current value supplied to the solenoid proportional valve PV in response to the change in the lever tilt angle when the operating lever 16 is operated from the neutral region N to the lowered position along the Z direction is set, for example, in the same manner as the change characteristics shown in Figure 5.

[0060] In this way, the speed at which the bucket 13 is dumped can be changed by selectively operating the mode changeover switch 42. Also, the operation of the boom 12 can be changed.

[0061] [Another embodiment] (1) In the above embodiment, the mode selector switch 42 is configured to switch between the first mode and the second mode, but it may also be configured to be switchable to a third mode, in which case the control unit 41 executes the following operations. In this case, the mode selector switch 42 is not limited to a push-type switch, and although not shown, a rotary-type switch configuration may also be adopted.

[0062] As shown in Fig. 6, the other-side regions (dump regions) of the operating lever 16 are set to a first dump region F1 as a first other-side region located on the neutral region N side, and a second dump region F2 as a second other-side region located on the opposite side of the neutral region N, and the mode selector switch 42 is configured to be switchable to a third mode in addition to the first and second modes. In the third mode, when the operating lever 16 is operated to the first dump region F1, the control unit 41 supplies to the electromagnetic proportional valve PV a current value corresponding to the quick dump position Ph, as shown in Fig. 7, and when the operating lever 16 is operated to the second dump region F2, the control unit 41 supplies to the electromagnetic proportional valve PV a current value corresponding to the standard dump position Pd.

[0063] Alternatively, as shown in FIG. 8, when the control lever 16 is operated to the first dump region F1, a current value corresponding to the standard dump position Pd may be supplied to the electromagnetic proportional valve PV, and when the control lever 16 is operated to the second dump region F2, a current value corresponding to the rapid dump position Ph may be supplied to the electromagnetic proportional valve PV.

[0064] With this configuration, the switching control valve (bucket control valve 32) can be effectively switched between a three-position switching state and a four-position switching state for proper use.

[0065] (2) In the above embodiment, the mode changeover means is configured such that the mode changeover switch 42 is provided on the grip portion of the operating lever in a state where it can be operated by a finger. However, instead of this configuration, the mode changeover switch may be provided on the operating panel, or instead of a switch, a touch panel type display or the like may be used to perform the changeover operation.

[0066] (3) In the above embodiment, the hydraulic cylinder is applied to a bucket cylinder of a front loader attached to a tractor, but the present invention is not limited to front loaders and can be applied to various devices such as wheel loaders and hydraulic excavators. Furthermore, the object to be operated is not limited to bucket cylinders, but the present invention can be applied to hydraulic cylinders that operate various other operated parts. Furthermore, the present invention is not limited to hydraulic cylinders, but can also be applied to hydraulic control devices that control the operation of other hydraulic actuators such as hydraulic motors. [Industrial Applicability]

[0067] The present invention can be applied to a hydraulic control device that controls a hydraulic cylinder. [Explanation of symbols]

[0068] 15 Bucket cylinder (hydraulic cylinder) 16 Operating lever (operating tool) 16a Grip 21 Hydraulic pump 26 Boom control valve (switching control valve) 32 Bucket control valve (switching control valve) 41 Control Unit 42 Mode changeover switch (mode changeover means) PV proportional solenoid valve PV1 One-side solenoid proportional valve PV2 Solenoid proportional valve on the other side E Squeeze area (one-sided area) N Neutral area F Dump area (other side area) F1 First dump area (first area on the other side) F2 Second dump area (second area on the other side) Ps Squeeze position (one side operating position) Pn neutral position Ph Quick dump position (first operating position on the other side) Pd Standard dump position (second operating position on the other side) Up: Raised position (one side operating position) Dw Lower position (first operating position on the other side) Fr Floating position (second operating position on the other side)

Claims

1. The hydraulic control system includes a switching control valve that switches the supply and discharge state of hydraulic oil, an electromagnetic proportional valve for switching the switching control valve, a control unit that controls the operation of the electromagnetic proportional valve based on an operation command from an operating tool, and mode switching means that can switch the control mode of the control unit between a first mode and a second mode, The operating tool can be operated in one side region, a neutral region, and an other side region, The switching control valve is the operating tool is switchable among a one-side operating position which is switched in response to operation of the operating tool from the neutral region to the one-side region, a neutral position which is switched to when the operating tool is not operated, an other-side first operating position which is switched to when the operating tool is operated from the neutral region to the other-side region, and an other-side second operating position which is different from the other-side first operating position and which is switched to when the operating tool is operated from the neutral region to the other-side region, the switching control valve is arranged in the one-side operating position, the neutral position, the other-side first operating position, and the other-side second operating position in this order, The control unit In the first mode, when the operating tool is operated from the neutral position to the other-side region, a current value corresponding to the other-side first operating position is supplied to the electromagnetic proportional valve; and a hydraulic control device configured to supply, to the electromagnetic proportional valve, a current value corresponding to the other-side second operating position when the operating tool is operated from the neutral position to the other-side region in the second mode.

2. the switching control valve switches the supply / discharge state of hydraulic oil from the hydraulic pump to the hydraulic actuator, At the one-side operating position, the hydraulic actuator is switched to a supply / discharge state for operating in a first operating direction; At the other side first operating position, the hydraulic actuator is switched to a supply / discharge state for operating in a first operating state in a second operating direction, 2. The hydraulic control device according to claim 1, wherein the other-side second operating position switches the hydraulic actuator to a supply / discharge state for operating the hydraulic actuator in a second operating direction in a second operating state different from the first operating state.

3. 3. The hydraulic control device according to claim 2, wherein the hydraulic actuator is a hydraulic cylinder, the first operating state is a high-speed operating state in which the hydraulic cylinder is operated at a high speed, and the second operating state is a low-speed operating state in which the hydraulic cylinder is operated at a low speed.

4. The hydraulic cylinder is configured as a double-acting type, 4. The hydraulic control device according to claim 3, wherein the switching control valve is configured so that, when switched to the other-side first operating position, return oil from the hydraulic cylinder merges with pressure oil supplied to the hydraulic cylinder.

5. the hydraulic actuator is a hydraulic cylinder; In the one-side operating position, hydraulic oil from the hydraulic pump is supplied to a first port of the hydraulic cylinder for operating the hydraulic cylinder in the first operating direction, At the other-side first operating position, hydraulic oil from the hydraulic pump is supplied to a second port of the hydraulic cylinder for operating the hydraulic cylinder in a second operating direction, 3. The hydraulic control device according to claim 2, wherein, in the other-side second operating position, the supply of hydraulic oil from the hydraulic pump to the first port and the second port is blocked, and the first port and the second port are connected to a drain oil passage that communicates with each other and discharges the hydraulic oil into a tank.

6. The switching control valve is configured to switch an operating position by sliding a spool using hydraulic pilot operating pressure, 6. The hydraulic control device according to claim 1, wherein the electromagnetic proportional valves include a one-side electromagnetic proportional valve capable of changing a pilot operating pressure for sliding the spool to one side, and a other-side electromagnetic proportional valve capable of changing a pilot operating pressure for sliding the spool to the other side.

7. The operating tool is configured as an operating lever that can be swung, 6. The hydraulic control device according to claim 1, wherein the mode switching means is configured as a switch provided on a grip portion of the operating tool so as to be finger-operable.

8. As the other-side region of the operating tool, an other-side first region located on the neutral region side and an other-side second region located on the opposite side of the neutral region are set, the mode switching means is configured to be switchable to a third mode, 6. The hydraulic control device according to claim 1, wherein, in the third mode, when the operating tool is operated to the other-side first region, the control unit supplies to the electromagnetic proportional valve a current value corresponding to the other-side first operating position, and when the operating tool is operated to the other-side second region, the control unit supplies to the electromagnetic proportional valve a current value corresponding to the other-side second operating position.

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