JP7404211B2 - Work equipment hydraulic system - Google Patents

Description

The present invention relates to a hydraulic system for a working machine such as a skid steer loader or a compact track loader.

BACKGROUND ART Conventionally, a work machine such as a skid steer loader and a compact track loader equipped with a variable displacement pump and a plurality of control valves has been disclosed in Patent Document 1.
The work machine of Patent Document 1 includes a variable displacement hydraulic pump that can change the flow rate of hydraulic oil to be discharged, a plurality of hydraulic actuators that are operated by the hydraulic oil, and a hydraulic actuator that can be switched to a plurality of positions and that is operated by the switching position. It is equipped with a plurality of control valves that control the flow rate.

Japanese Patent Application Publication No. 2016-125560

In the work machine of Patent Document 1, since the flow rate of hydraulic oil discharged by the variable displacement hydraulic pump can be made variable, the required flow rate of hydraulic oil is supplied to each of the plurality of hydraulic actuators. It has the advantage of being able to In particular, when the hydraulic actuator operates with a small amount of hydraulic oil, a small amount of hydraulic oil can be supplied, and when the hydraulic actuator operates with a large amount of hydraulic oil, a large amount of hydraulic oil can be supplied. In the variable displacement hydraulic pump for a working machine disclosed in Patent Document 1, the flow rate of hydraulic oil is made variable by operating the pump so that the LS differential pressure is constant. In such a case, a horsepower loss may occur due to the LS differential pressure.

The present invention was made to solve the problems of the prior art as described above, and an object of the present invention is to provide a hydraulic system for a working machine that can easily reduce horsepower loss as much as possible.

The technical means of the present invention for solving this technical problem are as follows.
A hydraulic system for a work machine according to one aspect of the present invention includes a variable displacement hydraulic pump that can change the flow rate of hydraulic fluid to be discharged, a plurality of hydraulic actuators operated by the hydraulic fluid , and a hydraulic system that can be switched to a plurality of switching positions. a plurality of control valves that control the flow rate flowing to each of the plurality of hydraulic actuators depending on the switched position among the plurality of switching positions, the plurality of control valves each controlling the flow rate of the flow from the variable displacement hydraulic pump. an input port into which the hydraulic oil input is input; an output port which outputs the hydraulic oil input into the input port; a flow rate reduction unit that reduces input hydraulic fluid and outputs it to the output port, and at least one control valve among the plurality of control valves is at the predetermined switching position among the plurality of switching positions. The plurality of hydraulic actuators include a flow rate increase part that outputs more hydraulic oil input to the input port to the output port than the flow rate decrease part when the hydraulic oil is in an increase position , which is a switching position different from the flow rate decrease part. These are a boom cylinder, a work implement cylinder, and a spare actuator. The plurality of control valves are a boom control valve that controls the boom cylinder, a work implement control valve that controls the work implement cylinder, and a first preliminary control valve that controls the preliminary actuator, and the boom control valve that controls the boom cylinder. The work implement control valve has the flow rate reduction section, and the first preliminary control valve has the flow rate reduction section and the flow rate increase section .

In one aspect of the present invention, when either the boom control valve or the work implement control valve is switched to the decrease position while the first preliminary control valve is switched to the increase position, the first The preliminary control valve returns from the increase position to the decrease position.

Further, in one aspect of the present invention, the plurality of control valves include a boom control valve that controls the boom cylinder, a work implement control valve that controls the work implement cylinder, and a first preliminary control valve that controls the preliminary actuator. a second preliminary control valve that controls the preliminary actuator; the boom control valve, the work implement control valve, and the first preliminary control valve include the flow rate reduction portion; , including the flow rate increasing section.

In one aspect of the present invention, the hydraulic system of the work machine includes an operating member that operates the preliminary actuator, and when the operating amount of the operating member is less than a threshold, the first preliminary control valve is moved to the reduced position. If the amount of operation of the operating member is equal to or greater than the threshold value, the second preliminary control valve is switched to the increasing position.
Further, in one aspect of the present invention, the second preliminary control valve includes the flow rate reducing portion, and when the second preliminary control valve is switched to the increasing position, the boom control valve and the work If any of the component control valves is switched to the decreased position, the second preliminary control valve returns from the increased position to the decreased position.

Further, in one aspect of the present invention, in the hydraulic system of the work machine, the first preliminary control valve and the second preliminary control valve have a pressure receiving part on which pilot pressure acts, and the first preliminary control valve has a pressure receiving part on which pilot pressure acts. The pressure receiving section and the pressure receiving section of the second preliminary control valve are connected through a pilot oil passage, and the second preliminary control valve applies pressure to the pressure receiving section of the second preliminary control valve via the pilot oil passage. When this occurs, it is possible to switch to a neutral position among the plurality of switching positions.

Further, in one aspect of the present invention, the hydraulic system of the work machine includes a detection oil passage and an interlocking valve that is connected to the detection oil passage and switches depending on the plurality of switching positions of the second preliminary control valve. and a pressure detection unit that detects pilot pressure of the detection oil passage, and the interlocking valve is configured to detect the detection when the second preliminary control valve is switched to the increasing position among the plurality of switching positions. It is possible to switch to a cutoff position where pilot oil introduced from the oil path to the interlocking valve is cut off.

Further, in one aspect of the present invention, the hydraulic system of the work machine includes an operation member that operates the preliminary actuator, a control device that outputs a control signal according to an operation amount of the operation member, and a control device that outputs a control signal according to an operation amount of the operation member. an operating valve that changes pilot pressure output in accordance with a control signal, the operating valve being either a pressure receiving part of the second preliminary control valve or a pressure receiving part of the interlocking valve that receives pilot pressure . is connected to, and the control device increases the pilot pressure output from the operating valve so that the pilot pressure detected by the pressure detection section becomes equal to or more than the threshold value when the operation amount of the operation member is equal to or greater than the threshold value. This causes the second preliminary control valve to switch to the increase position.

Further, in one aspect of the present invention, the control device may switch either the boom control valve or the work implement control valve to the decrease position while the second preliminary control valve is switched to the increase position. If so, the second preliminary control valve is switched to the decreasing position by lowering the pilot pressure output from the operating valve so that the pilot pressure of the detection oil path becomes less than a threshold value.
Further, in one aspect of the present invention, the control device changes the control signal output to the operating valve, and when the control signal is changed, the pilot pressure detected by the pressure detection section is equal to or higher than a threshold value. The value of the control signal is stored.

Further, in one aspect of the present invention, the interlocking valve may include a pilot control valve that is introduced from the detection oil passage into the interlocking valve when the second preliminary control valve is switched to the increasing position among the plurality of switching positions. It can be switched to a communication position where oil is communicated.
Further, in one aspect of the present invention, when the operation amount of the operation member is equal to or greater than a threshold value, the control device outputs from the operating valve such that the pilot pressure detected by the pressure detection section becomes less than the threshold value. By lowering the pilot pressure, the second preliminary control valve is switched to the increasing position.

Further, in one aspect of the present invention, the control device may switch either the boom control valve or the work implement control valve to the decrease position while the second preliminary control valve is switched to the increase position. If so, the second preliminary control valve is switched to the decreasing position by increasing the pilot pressure output from the operating valve so that the pilot pressure of the detection oil path becomes equal to or higher than a threshold value.
Further, in one aspect of the present invention, the control device outputs a control signal to the operating valve , and further, in one aspect of the present invention, the control device changes the control signal. A value of the control signal at which the pilot pressure detected by the pressure detection section is less than a threshold value when the pressure detection section is set is stored.

According to the present invention, horsepower loss can be reduced as much as possible.

FIG. 1 is a schematic diagram of a hydraulic system of a working machine in a first embodiment. FIG. 3 is an enlarged view of a plurality of control valves. FIG. 3 is a diagram showing the flow rate Q1 of the first preliminary control valve. It is a schematic diagram of the hydraulic system of the work machine in a 2nd embodiment. FIG. 2 is a diagram showing a flow rate Q1 of the first preliminary control valve, a flow rate Q2 of the second preliminary control valve, and a total flow rate Q3. It is a schematic diagram of the hydraulic system of the working machine in a 3rd embodiment. It is a figure which shows the modification of 3rd Embodiment. It is a figure which shows the modification different from FIG. 6A and FIG. 6B. FIG. 6B is a diagram showing changes in pilot pressure at the time of switching in FIG. 6A. FIG. 6B is a diagram showing changes in pilot pressure at the time of switching in FIG. 6A. It is a figure which shows the change of pilot pressure at the time of the switching of FIG. 6C. It is a schematic diagram of the hydraulic system of the working machine in a 4th embodiment. It is a figure showing the relationship between pilot pressure and operation amount. It is a figure which shows the modification of the hydraulic system of the working machine in 4th Embodiment. It is a figure which shows the modification different from FIG. 10A. This is a modification of FIG. 4. This is a modification of FIG. 11A. This is a modification of FIG. 11B. It is a side view showing a track loader which is an example of a work machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a hydraulic system for a working machine according to the present invention and a working machine equipped with this hydraulic system will be described with reference to the drawings as appropriate.
[First embodiment]
First, the overall structure of the work machine will be explained. As shown in FIG. 12, the work machine 1 includes a body 2, a cabin 3, a work device 4, and a traveling device 5. Although FIG. 12 shows a compact track loader as an example of a work machine, the work machine according to the present invention is not limited to a compact track loader, and may be a tractor, skid steer loader, backhoe, etc. . In the present invention, the front side of the driver seated in the driver's seat 8 of the work machine (left side in FIG. 12) is the front side, the rear side of the driver (the right side in FIG. 12) is the rear side, and the left side of the driver (the left side in FIG. 12) The description will be made assuming that the front side) is the left side and the driver's right side (the back side in FIG. 12) is the right side.

Cabin 3 is mounted on fuselage 2. This cabin 3 is provided with a driver's seat 8. The working device 4 is attached to the machine body 2. The traveling device 5 is provided outside the fuselage 2. A prime mover is mounted in the rear part of the fuselage 2.
The work device 4 includes a boom 10, a work implement 11, a lift link 12, a control link 13, a boom cylinder 14, and a work implement cylinder 15.

The boom 10 is provided on the right and left sides of the cabin 3 so as to be vertically swingable. The work tool 11 is, for example, a bucket, and the bucket 11 is provided at the tip (front end) of the boom 10 so as to be vertically swingable. The lift link 12 and the control link 13 support the base (rear part) of the boom 10 so that the boom 10 can swing vertically. The boom cylinder 14 moves the boom 10 up and down by expanding and contracting. The work tool cylinder 15 swings the bucket 11 by expanding and contracting.

The front parts of the left and right booms 10 are connected to each other by an irregularly shaped connecting pipe. The bases (rear parts) of each boom 10 are connected to each other by a circular connecting pipe.
The lift link 12, the control link 13, and the boom cylinder 14 are provided on the left and right sides of the fuselage 2, corresponding to the left and right booms 10, respectively.
The lift link 12 is provided vertically at the rear of the base of each boom 10. The upper part (one end side) of the lift link 12 is rotatably supported around a horizontal axis via a pivot shaft 16 near the rear of the base of each boom 10. Further, the lower part (the other end side) of the lift link 12 is rotatably supported near the rear of the body 2 via a pivot shaft 17 around a horizontal axis. Pivot axis 1
7 is provided below the pivot shaft 16.

The upper part of the boom cylinder 14 is rotatably supported around a horizontal axis via a pivot shaft 18 . The pivot shaft 18 is provided at the base of each boom 10 and at the front of the base. The lower portion of the boom cylinder 14 is rotatably supported around a horizontal axis via a pivot shaft 19 . The pivot shaft 19 is provided near the bottom of the rear portion of the body 2 and below the pivot shaft 18 .
The control link 13 is provided in front of the lift link 12. One end of this control link 13 is rotatably supported around a horizontal axis via a pivot shaft 20 . The pivot shaft 20 is provided in the body 2 at a position corresponding to the front of the lift link 12. The other end of the control link 13 is rotatably supported around a horizontal axis via a pivot shaft 21 . The pivot shaft 21 is provided in the boom 10 in front of and above the pivot shaft 17 .

By extending and contracting the boom cylinder 14, each boom 10 swings up and down around the pivot shaft 16 while the base of each boom 10 is supported by the lift link 12 and control link 13, and the tip of each boom 10 moves up and down. do. The control link 13 swings up and down about the pivot shaft 20 as each boom 10 swings up and down. The lift link 12 swings back and forth around the pivot shaft 17 as the control link 13 swings up and down.

Another work tool can be attached to the front of the boom 10 instead of the bucket 11. Examples of other working tools include attachments (preliminary attachments) such as hydraulic crushers, hydraulic breakers, angle brooms, earth augers, pallet forks, sweepers, mowers, and snow blowers. A connecting member 50 is provided at the front of the boom 10 on the left side. The connecting member 50 is a device that connects the hydraulic equipment installed on the preliminary attachment and a first pipe material such as a pipe provided on the boom 10. Specifically, a first pipe member can be connected to one end of the connecting member 50, and a second pipe member connected to a hydraulic device as a preliminary attachment can be connected to the other end. Thereby, the hydraulic oil flowing through the first pipe material passes through the second pipe material and is supplied to the hydraulic equipment.

The work implement cylinders 15 are arranged near the front of each boom 10, respectively. By expanding and contracting the work tool cylinder 15, the bucket 11 is swung. In this embodiment, each of the left and right traveling devices 5 is a crawler type (including a semi-crawler type) traveling device. Note that a wheel-type traveling device having front wheels and rear wheels may be employed.
As shown in FIG. 1, the hydraulic system of the working machine includes a first hydraulic pump P1, a second hydraulic pump P2, and a plurality of control valves 56.

The first hydraulic pump P1 can discharge hydraulic oil stored in the hydraulic oil tank 22. In particular, the first hydraulic pump P1 discharges hydraulic oil mainly used for control. The second hydraulic pump P2 is a variable displacement pump installed at a different position from the first hydraulic pump P1, and is capable of changing the hydraulic oil stored in the hydraulic oil tank 22. Note that among the hydraulic oil discharged from the first hydraulic pump P1, the hydraulic oil used for control may be referred to as pilot oil, and the pressure of the pilot oil may be referred to as pilot pressure.

A discharge oil passage 41 through which hydraulic oil (pilot oil) flows is provided on the discharge side of the first hydraulic pump P1. A plurality of control valves 56 are connected to the discharge oil passage 41 .
Each of the plurality of control valves 56 is a control valve that can be switched to a plurality of positions (switching positions) and controls a hydraulic actuator. Each of the plurality of control valves 56 controls, for example, the boom cylinder 14, which is one of the hydraulic actuators, the work tool cylinder 15, the preliminary actuator 26 provided in the preliminary attachment, and the like. The plurality of control valves 56 include a boom control valve 56A, a work implement control valve 56B, and a first preliminary control valve 56C. The boom control valve 56A is a valve that controls the boom cylinder 14, and the work implement control valve 56B is a valve that controls the work implement cylinder 15. The boom control valve 56A and the work implement control valve 56B are each pilot type direct-acting spool type three-position switching valves. The boom control valve 56A can be switched to a neutral position 80c, a first position 80a, and a second position 80b. The work implement control valve 56B is switched to a neutral position 82c, a first position 82a, and a second position 82b by pilot pressure.

The boom cylinder 14 is connected to the boom control valve 56A via an oil supply/discharge passage 96, and the work implement cylinder 15 is connected to the work implement control valve 56B via an oil supply/discharge passage 97.
The boom 10 and the bucket 11 can be operated using a control lever 58 provided around the driver's seat 8. The operating lever 58 is supported so as to be tiltable in front and rear, left and right, and diagonal directions from a neutral position. By tilting the operating lever 58, each pilot valve 59A, 59B, 59C, and 59D provided at the bottom of the operating lever 58 can be operated.

When the operating lever 58 is tilted forward, the descending pilot valve 59A is operated and pilot pressure is output from the descending pilot valve 59A. This pilot pressure acts on the pressure receiving portion of the boom control valve 56A, the boom control valve 56A switches to the first position 80a, and the boom 10 descends.
When the operating lever 58 is tilted rearward, the ascending pilot valve 59B is operated and pilot pressure is output from the ascending pilot valve 59B. This pilot pressure acts on the pressure receiving portion of the boom control valve 56A, the boom control valve 56A switches to the second position 80b, and the boom 10 rises.

When the operating lever 58 is tilted to the right, the bucket dump pilot valve 59C is operated and pilot pressure is output from the bucket dump pilot valve 59C. This pilot pressure acts on the pressure receiving portion of the work implement control valve 56B, the work implement control valve 56B switches to the first position 82a, and the bucket 11 performs a dumping operation.
When the operating lever 58 is tilted to the left, the bucket rake pilot valve 59D is operated and pilot pressure is output from the bucket rake pilot valve 59D. This pilot pressure acts on the pressure receiving portion of the work implement control valve 56B, the work implement control valve 56B switches to the second position 82b, and the bucket 11 performs a scooping operation.

The first preliminary control valve 56C is a valve that controls the preliminary actuator 26, and is a pilot type direct-acting spool type four-position switching valve. The first preliminary control valve 56C is switched to a neutral position 83c, a first position 83a, a second position 83b, and a third position 83d by pilot pressure. That is, the first preliminary control valve 56C controls the direction, flow rate, and pressure of the hydraulic fluid flowing toward the preliminary hydraulic actuator by switching between the first position 83a, the second position 83b, and the third position 83d.

As shown in FIGS. 1 and 2, a first oil supply/discharge path 81a and a second oil supply/discharge path 81b are connected to the first preliminary control valve 56C. One end of the first oil supply/discharge path 81a is connected to the first supply/discharge port 84 of the first preliminary control valve 56C, and a midway portion of the first oil supply/discharge path 81a is connected to the connecting member 50, The other end of the oil drain path 81a is connected to the preliminary actuator 26. One end of the second oil supply/discharge path 81b is connected to the second supply/discharge port 85 of the first preliminary control valve 56C, and a midway portion of the second oil supply/discharge path 81b is connected to the connecting member 50, The other end of the oil drain path 81b is connected to the preliminary actuator 26.

As shown in FIG. 1, the first preliminary control valve 56C is operated by a plurality of proportional valves 60. The proportional valve 60 is a solenoid valve whose opening degree can be changed by excitation. The plurality of proportional valves 60 are a first proportional valve 60A and a second proportional valve 60B. A first hydraulic pump P1 is connected to the first proportional valve 60A and the second proportional valve 60B via an oil passage 100. The proportional valves 60 (the first proportional valve 60A and the second proportional valve 60B) and the first preliminary control valve 56C are connected by a pilot oil passage 86. The pilot oil passage 86 is an oil passage that allows pilot oil to flow to the first preliminary control valve 56C via the proportional valve 60 (the first proportional valve 60A and the second proportional valve 60B).

Therefore, when the first proportional valve 60A is opened, pilot oil acts on the pressure receiving part 87a of the first preliminary control valve 56C via the pilot oil passage 86, and is applied to the pressure receiving part 87a depending on the opening degree of the first proportional valve 60A. (acting) pilot pressure is determined. Further, when the second proportional valve 60B is opened, pilot oil acts on the pressure receiving part 87b of the first preliminary control valve 56C via the pilot oil passage 86, and is applied to the pressure receiving part 87b depending on the opening degree of the second proportional valve 60B. (acting) pilot pressure is determined.

Excitation of the proportional valves 60 (first proportional valve 60A and second proportional valve 60B) is performed by a control device (first control device) 88. The control device 88 is composed of a CPU and the like. An operating member 89 such as a switch is connected to the control device 88, and based on the amount of operation of the operating member 89, the opening degrees of the first proportional valve 60A and the second proportional valve 60B are set. The pilot pressure of either the first proportional valve 60A or the second proportional valve 60B acts on the pressure receiving parts 87a and 87b of the control valve 56C, and the preliminary actuator 26 can be operated.

Note that the hydraulic system of the work machine is equipped with a load sensing system. The load sensing system controls the second hydraulic pump P2 so that the differential pressure between the highest load pressure during operation of the hydraulic actuator and the discharge pressure of the second hydraulic pump P2 is constant (discharge amount of the second hydraulic pump P2). control) system. The load sensing system includes a PLS oil passage 70 to which a pressure compensation valve 75 connected to a plurality of control valves 56 is connected, a PPS oil passage 71, a regulator 72, and a tilting piston 73.

Among the plurality of control valves 56 , the pressure with the highest load pressure (PLS signal pressure) acts on the PLS oil passage 70 , while the PPS oil passage 71 is transmitted to the regulator 72 . The regulator 72 operates the tilting piston 73 so that the differential pressure between the PPS signal pressure and the PLS signal pressure (PPS signal pressure - PLS signal pressure), which is the discharge pressure of the hydraulic fluid of the second hydraulic pump P2, becomes constant. let
Now, as shown in FIG. 2, the plurality of control valves 56 (boom control valve 56A, work implement control valve 56B, first preliminary control valve 56C) have an input port 90 and an output port 91. The input port 90 is a port into which hydraulic fluid discharged from the second hydraulic pump P2 (variable displacement hydraulic pump) is input. Specifically, the input port 90 of the boom control valve 56A is connected to the discharge oil passage 41 via the oil passage 41a, the work implement control valve 56B is connected to the discharge oil passage 41 via the oil passage 41b, The first preliminary control valve 56C is connected to the discharge oil passage 41 via the oil passage 41c. The output port 91 is an output port 91 that outputs the hydraulic oil input to the input port 90.

Further, the plurality of control valves 56 (boom control valve 56A, work implement control valve 56B, first preliminary control valve 56C) have a flow rate reducing portion 92. The flow rate reduction section 92 is a section that reduces the hydraulic fluid input to the input port 90 and outputs it to the output port 91. In other words, the flow rate reducing part 92 is a part that generates a pressure difference between the pressure of the hydraulic oil introduced into the input port 90 and the pressure of the hydraulic oil output from the output port 91. The flow rate reduction unit 92 is configured to select one of the plurality of switching positions (first positions 80a, 82a, 83a, second positions 80b, 82b, 83b, neutral positions 80c, 81c, 83c, third position 83d) of each control valve 56. , are provided at reduction positions (first positions 80a, 82a, 83a, second positions 80b, 82b, 83b), which are predetermined switching positions.

That is, in the boom control valve 56A, the flow reducing portions 92 are provided at the first position 80a and the second position 80b, which are the reducing positions, and in the work implement control valve 56B, the flow reducing parts 92 are provided at the first position 82a and the second position 80b, which are the reducing positions. In the first preliminary control valve 56C, it is provided at a first position 83a and a second position 83b, which are the reduction positions.
The flow rate reduction part 92 has an internal oil passage 92a that communicates the input port 90 and the output port 91 when in the reduction position, and a cross-sectional area (opening area) provided in the internal oil passage 92a through which hydraulic oil passes. 92b. The opening area of the throttle portion 92b is set to be substantially the same for the boom control valve 56A, the work implement control valve 56B, and the first preliminary control valve 56C.

In addition, in each of the boom control valve 56A, the work implement control valve 56B, and the first preliminary control valve 56C, the hydraulic oil output from the output port 91 returns to the respective control valve 56 side via the oil path 76. , passes through oil passages (internal oil passages) 95 other than the flow rate reduction part 92 provided at the reduction position, and is output to each of the oil supply and drainage passages 81a, 81b, 96, and 97.
In the embodiment described above, the flow rate reducing portion 92 is provided in the plurality of control valves 56 (the boom control valve 56A, the work implement control valve 56B, and the first preliminary control valve 56C), but among the plurality of control valves 56, at least One control valve has a flow rate increase part 93 that outputs more hydraulic oil input to the input port 90 to the output port 91 than the flow rate decrease part 92 . In this embodiment, the first preliminary control valve 56C has a flow increasing portion 93.

The flow increasing portion 93 is a portion that outputs more hydraulic oil to the output port 91 than the flow reducing portion 92. In other words, the flow rate increasing portion 93 is a portion that does not generate a pressure difference as much as possible between the pressure of the hydraulic oil introduced into the input port 90 and the pressure of the hydraulic oil output from the output port 91. and the output port 91 , and the opening area (cross-sectional area) through which the hydraulic oil passes is larger than that of the flow rate reduction part 92 . More specifically, the flow rate increasing portion 93 is provided at the third position 83d, which is the increasing position, in the first preliminary control valve 56C. The flow increasing portion 93 can allow approximately the maximum amount of hydraulic oil to pass through when the discharge amount of the second hydraulic pump P2 reaches the maximum. In the first preliminary control valve 56C as well, the hydraulic oil output from the output port 91 passes through the oil passage (internal oil passage) 99 other than the flow rate increasing part 93 provided at the increasing position, and then passes through the first oil supply and drainage oil passage. The signal is output to path 81a.

FIG. 3 shows an example of the flow rate Q1 when the spool of the first preliminary control valve 56C having the flow rate decreasing part 92 and the flow rate increasing part 93 is operated. In FIG. 3, the horizontal axis represents the amount of movement of the spool, and the vertical axis represents the flow rate of hydraulic oil output from the output port 91. In the description of FIG. 3, it is assumed that the boom control valve 56A and the work implement control valve 56B are not operated.
The control device 88 increases the opening degree of the first proportional valve 60A according to the amount of operation of the operation member 89. The pilot pressure acting on the pressure receiving portion 87a of the first preliminary control valve 56C increases in accordance with the opening degree of the first proportional valve 60A, and switches from the neutral position 82c side to the first position 83a side. Here, in the first preliminary control valve 56C, when the spool position is in the decreasing position (notch region), that is, in the first position 83a, the flow rate of the hydraulic oil gradually increases as shown in line L1. Q1 increases. On the other hand, when the spool position passes through the first position 83a [decreasing position (notch area)] and reaches the third position 83d, which is the increasing position (land removal area), as shown in line L2, the hydraulic oil The flow rate Q1 increases all at once.

Here, when the first preliminary control valve 56C is switched to the increase position and the boom control valve 56A and the work implement control valve 56B are operated, the control device 88 controls the operation of the boom control valve 56A and the work implement control valve. When any of the control valves 5B is switched to a decreasing position (first position 80a, 82a, second position 80b, 82b), the control device 88 controls the operation amount of the operating member 89 to correspond to the increasing position. Even if the amount is small, the signal (control signal) that excites the first proportional valve 60A, that is, the current, is reduced to move the first preliminary control valve 56C from the increasing position (third position 83d) to the decreasing position (first position). 83a). That is, when the boom control valve 56A and the work implement control valve 56B are operated, the control device 88 controls the first preliminary control valve 56C by reducing the stroke amount of the spool from the neutral position 83c. The valve 56C is switched from the increase position to the decrease position (first position 83a).

The hydraulic system of the work equipment includes a variable capacity hydraulic pump (second hydraulic pump) P2 that can change the flow rate of the discharged hydraulic oil, and a plurality of hydraulic actuators (boom cylinder 14, work implement cylinder 15, spare pump) operated by the hydraulic oil. actuator 26), and a plurality of control valves 56 (56A, 56B, 56B, 56C), and the plurality of control valves 56 (56A, 56B, 56C) have an input port 90 into which the hydraulic oil discharged from the variable displacement hydraulic pump P2 is input, and an input port 90 through which the hydraulic oil input into the input port 90 is input. An output port 91 that outputs an output, and a flow rate reduction section 92 that reduces the hydraulic fluid input to the input port 90 and outputs it to the output port 91 when the reduction position is a predetermined switching position among the plurality of switching positions. When at least one control valve 56 among the plurality of control valves 56 (56A, 56B, 56C) is in the increased position, which is a switching position different from a predetermined one among the plurality of switching positions, an input signal is input to the input port 90. The flow rate increasing part 93 outputs more of the hydraulic oil to the output port 91 than the flow rate reducing part 92.

According to this, by switching the plurality of control valves 56 to the reduction positions corresponding to the flow rate reduction portions 92, the hydraulic oil required for the hydraulic actuators (boom cylinder 14, work tool cylinder 15, reserve actuator 26) can be maintained as usual. is supplied by the variable displacement hydraulic pump (second hydraulic pump) P2, and by switching to the increasing position corresponding to the flow increasing part 93, more is supplied to the hydraulic actuators (boom cylinder 14, work implement cylinder 15, reserve actuator 26). hydraulic oil can be supplied by the variable displacement hydraulic pump (second hydraulic pump) P2. In other words, since at least one control valve 56 among the plurality of control valves 56 (56A, 56B, 56C) has the flow increasing portion 93, when the variable displacement hydraulic pump (second hydraulic pump) P2 is operated It is possible to reduce the LS differential pressure to approximately zero, and it is possible to easily reduce horsepower loss as much as possible.

The plurality of control valves 56 include a boom control valve 56A that controls the boom cylinder 14, a work implement control valve 56B that controls the work implement cylinder 15, and a first preliminary control valve 56C that controls the preliminary actuator. The control valve 56A and the work implement control valve 56B have a flow rate reduction section 92, and the first preliminary control valve 56C has a flow rate decrease section 92 and a flow rate increase section 93.
According to this, when operating the boom cylinder 14 (boom 10) and the work implement cylinder 15 (work implements such as the bucket 11), the boom control valve 56A is The work implements such as the boom 10 and the bucket 11 can be operated by the work implement control valve 56B. On the other hand, when a large-capacity reserve actuator (large-capacity reserve actuator) that requires a large amount of hydraulic oil is installed, the large-capacity reserve actuator can be operated by the first reserve control valve 56C. When a spare actuator that operates with standard hydraulic oil (standard side spare actuator) is installed, the spare actuator can be operated as usual.

If either the boom control valve 56A or the work implement control valve 56B is switched to the decrease position while the first preliminary control valve 56C is switched to the increase position, the first preliminary control valve 56C is switched from the increase position to the decrease position. Return to position. According to this, the preliminary actuator can also be operated while operating the work implements 11 such as the boom 10 and the bucket. In other words, when operating the work implement 11 such as the boom 10 or the bucket, it is possible to prevent the hydraulic oil from flowing concentrated only to the standby actuator, and to perform the work in a well-balanced manner.
[Second embodiment]
The hydraulic system for a work machine according to the second embodiment shown in FIG. 4 is an embodiment in which the preliminary control valve is modified. As shown in FIG. 4, boom control valve 56A and implement control valve 56B are not shown, but are similar to the embodiments described above and to FIG. Further, the same applies to the configurations other than the boom control valve 56A and the work implement control valve 56B. In the second embodiment, configurations different from those in the first embodiment will be described, and descriptions of common configurations will be omitted.

As shown in FIGS. 1 and 4, the plurality of control valves 56 include a boom control valve 56A, a work implement control valve 56B, a first preliminary control valve 56C, and a second preliminary control valve 56D. . The first preliminary control valve 56C is a pilot-type direct-acting spool type three-position switching valve that switches between a neutral position 83c, a first position 83a, and a second position 83b, and a first position 83a and a second position 83b. A flow rate reducing portion 92 is provided at position 83b. That is, in the second embodiment, the flow rate increasing portion 93 is not provided in the first preliminary control valve 56C.

The second preliminary control valve 56D is a valve that controls the preliminary actuator 26 similarly to the first preliminary control valve 56C, and is a pilot type direct-acting spool type three-position switching valve. The second preliminary control valve 56D is switched to a first position 110a, a second position 110b, and a neutral position 110c by pilot pressure. That is, the second preliminary control valve 56D controls the direction, flow rate, and pressure of the hydraulic fluid toward the preliminary hydraulic actuator by switching between the first position 110a, the second position 110b, and the neutral position 110c.

The second preliminary control valve 56D has an input port 90, an output port 91, a third supply/discharge port 104, a fourth supply/discharge port 105, a flow rate reduction section 92, and a flow rate increase section 94.
The input port 90 is connected to an oil passage 41d branched from the discharge oil passage 41. The third oil supply/discharge port 104 is connected to the first oil supply/discharge passage 81a via an oil passage (third oil supply/discharge passage) 107, and the fourth oil supply/discharge port 105 is connected to the first oil supply/discharge passage 81a via an oil passage (third oil supply/discharge passage) 107. ) 108 to the second oil supply/drainage path 81b.

The flow rate reducing portion 92 is provided in a portion of the second preliminary control valve 56D corresponding to the first position 110a which is the decreasing position, and the flow increasing portion 94 is provided in a portion corresponding to the second position 110b which is the increasing position. ing. In the second preliminary control valve 56D as well, the hydraulic oil output from the output port 91 returns from the oil passage 76 to the second preliminary control valve 56D side, and the hydraulic oil is returned to the second preliminary control valve 56D side from the oil passage 76 (internal The oil passes through the oil passage (oil passage) 99 and is output to the first oil supply and drainage passage 81a.

Further, the second preliminary control valve 56D has a first pressure receiving part 121a and a second pressure receiving part 121b. The first pressure receiving part 121a is connected to a third proportional valve 60C, which is one of the plurality of proportional valves 60, via an oil passage 125. An oil passage 100 is connected to the third proportional valve 60C, and hydraulic oil discharged from the first hydraulic pump P1 is supplied through the oil passage 100.
The second pressure receiving portion 121b of the second preliminary control valve 56D is connected to the pilot oil passage 86. That is, the pressure receiving part 87b of the first preliminary control valve 56C and the second pressure receiving part 121b of the second preliminary control valve are connected by the pilot oil passage 86.

FIG. 5 shows the flow rate Q1 when the spool of the first preliminary control valve 56C is operated, the flow rate Q2 when the spool of the second preliminary control valve 56D is operated, and the flow rate Q3 of the hydraulic oil flowing through the first oil supply and drain path 81a. FIG. In the description of FIG. 5, it is assumed that the boom control valve 56A and the work implement control valve 56B are not operated.
When the operating amount of the operating member 89 is within the first range (small to medium) A1 (less than the threshold), the control device 88 increases only the opening degree of the first proportional valve 60A in accordance with the operating amount. To go. In this case, since the first preliminary control valve 56C is in the first position 83a [reduction position (notch region)], the flow rate Q1 of the hydraulic oil gradually increases as shown by line L10. Further, when the operating amount of the operating member 89 is within the second range (medium to slightly high) A2 (less than the threshold), the opening degree of the first proportional valve 60A is gradually increased, while the operating amount is Accordingly, the opening degree of the third proportional valve 60C is increased in accordance with the manipulated variable. In this case, since the second preliminary control valve 56D is in the first position 110a [reduction position (notch region)], the flow rate Q2 of the hydraulic oil gradually increases as shown in line L11, and as shown in line L12. Thus, the total flow rate Q3 also gradually increases.

Furthermore, when the operating amount of the operating member 89 is equal to or greater than the threshold value, that is, within the third range (slightly higher to maximum) A3, the opening degree of the third proportional valve 60C is maximized. Since the second preliminary control valve 56D is in the second position 110b [increase position (land removal area)], the total flow rate Q3 increases to the maximum, as shown on line L12.
Note that when the boom control valve 56A and the work implement control valve 56B are operated in a situation where the second preliminary control valve 56D is in the second position 110b [increase position (land removal area)], the control device 88 By lowering the control signal (current) output to the third proportional valve 60C, the second preliminary control valve 56D is returned to the first position 110a [decreased position (notch region)] or the neutral position 110c. In addition, since the second pressure receiving part 121b of the second preliminary control valve 56D is connected to the pilot oil passage 86, the pressure of the pilot oil (pilot pressure) output from the first proportional valve 60A causes the first preliminary control valve to 56C to the second position 83b, the second preliminary control valve 56D can be forcibly returned to the neutral position 110c.

The plurality of control valves 56 include a boom control valve 56A, a work implement control valve 56B, a first preliminary control valve 56C, and a second preliminary control valve 56D. The first preliminary control valve 56C includes a flow rate decreasing section 92, and the second preliminary control valve 56D includes a flow rate increasing section 93. According to this, among the first preliminary control valve 56C and the second preliminary control valve 56D, the first preliminary control valve 56C can operate the standard side preliminary actuator, while the second preliminary control valve 56D can actuate the large capacity actuator. The mold reserve actuator can be actuated. That is, at least the two preliminary control valves, the first preliminary control valve 56C and the second preliminary control valve 56D, can operate both the standard preliminary actuator and the large capacity preliminary actuator. In particular, at least the two preliminary control valves, the first preliminary control valve 56C and the second preliminary control valve 56D, can be switched between a decreasing position corresponding to the flow rate decreasing section 92 and an increasing position corresponding to the flow rate increasing section 93. As a result, the apparent amount of spool movement (the sum of the amount of spool movement of the first preliminary control valve 56C and the amount of spool movement of the second preliminary control valve 56D) becomes longer, improving the accuracy of flow rate control. can be done.

The hydraulic system of the work machine includes an operating member 89 that operates a preliminary actuator, and when the operating amount of the operating member 89 is less than a threshold value, the first preliminary control valve 56C is switched to the decreasing position, and the operating member 89 is operated. If the amount is above the threshold, the second preliminary control valve 56D is switched to the increase position. According to this, for example, as shown in FIG. The actuator (standard spare actuator, large capacity spare actuator) can be moved precisely and finely according to the amount of operation, and when the amount of operation of the operation member 89 is above the threshold (third range (slightly high to maximum) A3), A large capacity standby actuator can be activated.

The second preliminary control valve 56D has a flow rate reduction portion 92, and when the second preliminary control valve 56D is switched to the increase position, either the boom control valve 56A or the work implement control valve 56B is in the decrease position. When switched, the second preliminary control valve 56D returns from the increase position to the decrease position.
According to this, the preliminary actuator can also be operated while operating the work implements 11 such as the boom 10 and the bucket. In other words, when operating the work implement 11 such as the boom 10 or the bucket, it is possible to prevent the hydraulic oil from flowing concentrated only to the standby actuator, and to perform the work in a well-balanced manner.
[Third embodiment]
The hydraulic system for a work machine according to the third embodiment shown in FIG. 6A is an embodiment in which increased position detection is added. As shown in FIG. 6A, boom control valve 56A and implement control valve 56B are not shown, but are similar to the embodiments described above and to FIG. Further, the same applies to the configurations other than the boom control valve 56A and the work implement control valve 56B. In the third embodiment, configurations different from those in the first embodiment will be described, and descriptions of common configurations will be omitted. FIG. 7A is a diagram showing the relationship between the spool position and pilot pressure in the hydraulic system of FIG. 6A.

The hydraulic system of the work machine includes an interlocking valve 130. The interlocking valve 130 is a valve that switches according to a plurality of switching positions of the second preliminary control valve 56D. That is, the interlocking valve 130 is a valve that is switched in conjunction with the operation of the spool of the second preliminary control valve 56D. The interlocking valve 130 is a three-position switching valve, and is switchable between a shutoff position 130a and a plurality of communication positions 130b and 130c. The interlocking valve 130 switches to the communicating position 130c when the second preliminary control valve 56D is in the neutral position 110c, switches to the communicating position 130b when the second preliminary control valve 56D is in the first position 110a, and switches to the communicating position 130b when the second preliminary control valve 56D is in the first position 110a. When the preliminary control valve 56D is in the second position 110b, it switches to the shutoff position 130a.

In other words, the interlocking valve 130 is in the cutoff position 130a when the second preliminary control valve 56D is switched to the second position 110b [increase position (land removal area)] among the plurality of switching positions (110a, 110b, 110c). When the second preliminary control valve 56D is switched to a position other than the second position 110b [increase position (land removal area)], it can be switched to the communication positions 130b and 130c.

The interlocking valve 130 has a pressure receiving part 139. The pressure receiving part 139 of the interlocking valve 130 is connected to the third proportional valve 60C, that is, the operating valve via an oil passage 134. By changing the pressure of the hydraulic oil (pilot oil) output from the third proportional valve 60C (operating valve), the interlocking valve 130, that is, the second preliminary control valve 56D can be switched.
Further, the interlocking valve 130 is connected to a detection oil passage 135. Specifically, the interlocking valve 130 has an input port 131 and an output port 132, a detection oil passage 135 is connected to the input port 131, and a discharge oil passage 136 is connected to the output port 132. The detection oil passage 135 is connected to the oil passage 100, and a constriction portion 137 is connected thereto. Further, a pressure detection unit 138 that detects the pressure (pilot pressure) of hydraulic oil (pilot oil) flowing through the detection oil path 135 is connected. The pressure detection unit 138 is a pressure sensor or a pressure switch.

The pressure detection section 138 is connected to the control device 88. The control device 88 can change the control signal output to the third proportional valve (operating valve) 60C. For example, the control device 88 changes the operating amount from the minimum control signal (control signal corresponding to the neutral position) when the operating amount of the operating member 89 is set to the minimum (neutral position) to the maximum (maximum position). The value of the control signal, that is, the current value, is changed up to the maximum control signal (control signal corresponding to the maximum position). That is, the control device 88 causes the spool of the second preliminary control valve 56D to pass from the neutral position 110c to the first position 110a [decreasing position (notch region)] by the third proportional valve (operating valve) 60C. Switch to position 2 110b [increase position (land removal area)].

Here, when the second preliminary control valve 56D is in the neutral position 110c and the first position 110a [reduced position (notch region)], the interlocking valve 130 is in the communication position 130b, 130c, so as shown in FIG. 7A. The pilot pressure V10 detected by the pressure detection unit 138 is approximately zero. When the second preliminary control valve 56D switches from the first position 110a [decrease position (notch region)] to the second position 110b [increase position (land removal region)], the interlocking valve 130 switches to the cutoff position 130a. Therefore, the pilot pressure V10 detected by the pressure detection unit 138 increases rapidly. That is, the point P10 at which the pilot pressure V10 detected by the pressure detection unit 138 (the pilot pressure when the third proportional valve 60C (operating valve) is operated) suddenly increases is the first position 110a [reduction position (notch area)]. )] to the second position 110b [increase position (land removal area)]. That is, the pressure at time P10 is the threshold value V11 at which the pressure is switched to the second position 110b [increase position (land removal area)].

The control device 88 controls the value of the control signal (current value) at the time point P10 when the pilot pressure V10 detected by the pressure detection unit 138 suddenly increases, and the third value corresponding to the value (current value) of the control signal at the time point P10. Store the current value of the proportional valve (operating valve) 60C. The control device 88 stores the relationship between the value of the control signal (switching current value) and the switching operation amount of the operating member 89 when the second position 110b [increase position (land removal area)] is reached. In summary, the control device 88 determines the current value (switching current value) of the third proportional valve (operating valve) 60C when the pilot pressure V10 detected by the pressure detection unit 138 exceeds the threshold value V11, that is, the third proportional valve ( After storing the pilot pressure output by the operating valve (operating valve) 60C, the third proportional valve (operating valve) 60C is controlled to switch to the increase position (land removal region).

When the operation amount of the operation member 89 is equal to or higher than the threshold value (switching operation amount), the control device 88 controls the third proportional valve 60C (operating valve ), the second preliminary control valve 56D is switched to the second position 110b [increase position (land removal region)]. The control device 88 makes the control signal output to the third proportional valve 60C (operating valve), that is, the current value, equal to or higher than the switching current value.

Further, the control device 88 is configured to switch either the boom control valve 56A or the work implement control valve 56B to the decrease position while the second preliminary control valve 56D is switched to the second position 110b [increase position (land removal area)]. (first position 80a, 82a, second position 80b, 82b), the pilot pressure output from the third proportional valve 60C (operating valve) is adjusted so that the pilot pressure in the detection oil passage 135 becomes less than the threshold value V11. By lowering it, the second preliminary control valve 56D is switched to the first position 110a [reduction position (notch region)]. The control device 88 makes the control signal, that is, the current value, output to the third proportional valve 60C (operating valve) less than the switching current value.

Note that the interlocking valve 130 may be changed as shown in FIG. 6B. Specifically, the interlocking valve 130 switches to the blocking position 130a when the second preliminary control valve 56D is in the neutral position 110c, and switches to the communicating position 130b when the second preliminary control valve 56D is in the first position 110a. When the second preliminary control valve 56D is in the second position 110b, it is switched to the cutoff position 130c. In the case of the linked valve 130 in FIG. 6B, the pilot pressure V10 detected by the pressure detection unit 138 changes as shown in FIG. 7B. Similarly to FIG. 7A, FIG. 7B also shows that the point P10 at which the pilot pressure V10 (the pilot pressure when the third proportional valve 60C (operating valve) is activated) suddenly increases is the first position 110a [reduction position (notch region )] to the second position 110b [increase position (land removal area)]. When the operation amount of the operation member 89 is equal to or higher than the threshold value (switching operation amount), the control device 88 controls the third proportional valve 60C (operating valve ), the second preliminary control valve 56D is switched to the second position 110b [increase position (land removal region)].

Further, as shown in FIG. 6C, the interlocking valve 130 may be changed. Specifically, the interlocking valve 130 switches to the blocking position 130a when the second preliminary control valve 56D is in the neutral position 110c, and switches to the communicating position 130c when the second preliminary control valve 56D is in the second position 110b. When the second preliminary control valve 56D is in the first position 110a, it is switched to the shutoff position 130b. In other words, when the second preliminary control valve 56D is switched to the second position 110b, the pilot pressure detected by the pressure detection unit 138 decreases, which indicates that the second preliminary control valve 56D has been switched to the second position 110b. can be detected.

In the case of the interlocking valve 130 in FIG. 6C, the pilot pressure V10 detected by the pressure detection unit 138 changes as shown in FIG. 7C. In the case of FIG. 7C, unlike FIGS. 7A and 7B, the time point P11 when the pilot pressure V10 (the pilot pressure when the third proportional valve 60C (operating valve) is operated) suddenly decreases is at the first position 110a[ This is the point in time when the position is switched from the decreased position (notch area) to the second position 110b [increased position (land removal area)]. When the operation amount of the operation member 89 is equal to or greater than a threshold value (switching operation amount), the control device 88 controls the pilot pressure V10 detected by the pressure detection unit 138 to be less than the threshold value V12, for example, to make the pilot pressure V10 approximately zero. By lowering the pilot pressure output from the third proportional valve 60C (operating valve), the second preliminary control valve 56D is switched to the second position 110b [increase position (land removal region)].

In the case of FIG. 6C as well, the control device 88 detects the value of the control signal (current value) at the time point P11 when the pilot pressure V10 detected by the pressure detection unit 138 suddenly decreases, and the value (current value) of the control signal at the time point P11. The current value of the third proportional valve (operating valve) 60C corresponding to is stored. The control device 88 stores the relationship between the value of the control signal (switching current value) and the switching operation amount of the operating member 89 when the second position 110b [increase position (land removal area)] is reached. In summary, the control device 88 controls the current value (switching current value) of the third proportional valve (operating valve) 60C when the pilot pressure V10 detected by the pressure detection unit 138 becomes less than the threshold value V12, that is, the third proportional valve (Operation valve) 60C memorizes the pilot pressure output and then controls the third proportional valve (operation valve) 60C to switch to the increase position (land removal area).

Further, the control device 88 controls the boom control valve 56A and the work implement control valve 56B with the second preliminary control valve 56D switched to the second position 110b [increase position (land removal region)]. When either is switched to the decreasing position (first position 80a, 82a, second position 80b, 82b), the third proportional valve 60C (operating valve) The second preliminary control valve 56D is switched to the first position 110a [reduction position (notch region)] by increasing the pilot pressure output from the second preliminary control valve 56D. The control device 88 makes the control signal output to the third proportional valve 60C (operating valve), that is, the current value, equal to or higher than the switching current value.

The hydraulic system of the work machine includes a detection oil passage 135, an interlocking valve 130 that is connected to the detection oil passage 135 and switches according to a plurality of switching positions of the second preliminary control valve 56D, and a pilot pressure of the detection oil passage 135. The interlocking valve 130 includes a pressure detecting section 138 for detecting a pressure, and the interlocking valve 130 has a pilot pressure that is introduced into the interlocking valve 130 from the detection oil passage 135 when the second preliminary control valve 56D is switched to the increasing position among the plurality of switching positions. It is possible to switch to the cutoff position 130a where oil is cut off.

According to this, the pressure detected by the pressure detection unit 138 (pilot pressure ), it is possible to more accurately judge whether it is the second position 110b [increase position (land removal area)].
The hydraulic system of the work machine includes an operation member 89 that operates a preliminary actuator, a control device 88 that outputs a control signal according to the amount of operation of the operation member 89, and a pilot pressure that is output according to the control signal of the control device 88. The operating valve (proportional valve 60C) is either a pressure receiving part that receives the pressure of the pilot of the second preliminary control valve 56D or a pressure receiving part that receives the pressure of the pilot of the interlocking valve 130. When the operation amount of the operating member 89 is equal to or greater than the threshold value, the control device 88 controls the pilot output from the operating valve (proportional valve 60C) so that the pilot pressure detected by the pressure detection unit 138 becomes equal to or greater than the threshold value. By increasing the pressure, the second preliminary control valve 56D is switched to the increasing position.

According to this, when the operation amount of the operation member 89 is equal to or greater than the threshold value, the second preliminary control valve 56D can be accurately set to the second position 110b [increase position (land removal region)].
The control device 88 controls the pilot pressure of the detection oil passage 135 when either the boom control valve 56A or the work implement control valve 56B is switched to the decrease position while the second preliminary control valve 56D is switched to the increase position. The second preliminary control valve 56D is switched to the decreasing position by lowering the pilot pressure output from the operating valve (proportional valve 60C) so that it becomes less than the threshold value.

According to this, when the operation amount of the operation member 89 is less than the threshold value, the second preliminary control valve 56D can be accurately brought to the first position 110a [reduction position (notch region)].
The control device 88 changes the control signal output to the operating valve (proportional valve 60C), and also determines the value of the control signal at which the pilot pressure detected by the pressure detection unit 138 becomes equal to or higher than the threshold value when the control signal is changed. Remember. According to this, the value of the control signal output by the control device 88 when setting the second preliminary control valve 56D to the first position 110a [decreasing position (notch region)], and the value of the control signal outputted by the control device 88 when setting the second preliminary control valve 56D to the first position 110a [decreasing position (notch region)] 110b [increase position (land removal area)] can be accurately correlated with the value of the control signal output by the control device 88, and control accuracy can be improved.

The interlocking valve 130 can be switched to a communication position 130c in which pilot oil introduced from the detection oil passage 135 to the interlocking valve 130 is communicated when the second preliminary control valve 56D is switched to an increasing position among the plurality of switching positions. be. According to this, by switching the interlocking valve 130 to the communication position 130c, it is possible to more accurately determine whether the second position 110b [increase position (land removal region)] is reached based on the pressure (pilot pressure) detected by the pressure detection unit 138. can be judged.

When the operation amount of the operation member 89 is equal to or greater than the threshold value, the control device 88 lowers the pilot pressure output from the operating valve (proportional valve 60C) so that the pilot pressure detected by the pressure detection unit 138 becomes less than the threshold value V12. By doing so, the second preliminary control valve 56D is switched to the increase position.
According to this, when the operation amount of the operation member 89 is equal to or greater than the threshold value, the second preliminary control valve 56D can be accurately set to the second position 110b [increase position (land removal area)].

The control device 88 controls the pilot pressure of the detection oil passage 135 when either the boom control valve 56A or the work implement control valve 56B is switched to the decrease position while the second preliminary control valve 56D is switched to the increase position. The second preliminary control valve 56D is switched to the decreasing position by lowering the pilot pressure output from the operating valve (proportional valve 60C) so that it becomes less than the threshold value V12.
According to this, when the operation amount of the operation member 89 is less than the threshold value, the second preliminary control valve 56D can be accurately brought to the first position 110a [reduction position (notch region)].

The control device 88 changes the control signal output to the operating valve (proportional valve 60C), and also sets the value of the control signal such that the pilot pressure detected by the pressure detection unit 138 becomes less than the threshold value V12 when the control signal is changed. remember.
According to this, the value of the control signal output by the control device 88 when setting the second preliminary control valve 56D to the first position 110a [decreasing position (notch region)], and the value of the control signal outputted by the control device 88 when setting the second preliminary control valve 56D to the first position 110a [decreasing position (notch region)] 110b [increase position (land removal area)] can be accurately correlated with the value of the control signal output by the control device 88, and control accuracy can be improved.
[Fourth embodiment]
FIG. 8 shows a hydraulic system for a working machine in the fourth embodiment. The working machine hydraulic system of the fourth embodiment is a modification of the working machine hydraulic system of the first embodiment. As shown in FIG. 8, the first preliminary control valve 56C is not provided with the third position 83d. That is, the first preliminary control valve 56C is not provided with the flow increasing portion 93. The other control valves 56, boom control valve 56A, and work implement control valve 56B are the same as those in the first embodiment.

FIG. 9 shows the amount of operation of the operating member 89 and the amount of movement of the spool of the first preliminary control valve 56C, that is, the pilot pressure applied from the first proportional valve 60A to the pressure receiving portion 87a.
As shown in FIG. 9, when only the operating member 89 (only the first preliminary control valve 56C) is operated (single operation), the control device 88 controls the first proportional valve 60A as shown in line L51. The control signal (current) etc. output to the control valve 89 is increased in accordance with the amount of operation of the operating member 89, and the pressure acting on the pressure receiving portion 87a of the first preliminary control valve 56C is gradually increased.

On the other hand, in a state where the operating member 89 (first preliminary control valve 56C) and the operating lever 58 (either or both of the boom control valve 56A and the work implement control valve 56B) are operated (combined operation), As shown in line L52, the control device 88 raises the control signal (current) etc. output to the first proportional valve 60A halfway according to the amount of operation of the operation member 89, so that the amount of operation of the operation member 89 exceeds a predetermined value. If so, the control signal (current) output to the first proportional valve 60A is set lower than the line L51. That is, when the first preliminary control valve 56C is operated independently, the control device 88 gradually moves the spool of the first preliminary control valve 56C from the minimum position to the maximum position in accordance with the operating member 89. On the other hand, when the first preliminary control valve 56C is operated in a complex manner, the control device 88 gradually moves the spool of the first preliminary control valve 56C from the minimum position to an intermediate position in accordance with the operation member 89; Stop at an intermediate position (a position on the neutral side of the maximum position) so that it does not reach the maximum position.

In particular, when the boom control valve 56A and the first preliminary control valve 56C perform a combined operation, the control device 88 controls the pilot pressure output from the first proportional valve 60A even if the operating amount of the operating member 89 is the maximum. , can be smaller than the maximum value. In the embodiment described above, the first proportional valve 60A has been described, but the case where the second proportional valve 60B is operated instead of this is also the same as the first proportional valve 60A. That is, the first proportional valve 60A may be replaced with the second proportional valve 60B.

As shown in FIG. 10A, an interlocking valve 230 may be applied to the first preliminary control valve 56C. As shown in FIG. 10A, the interlocking valve 230 is connected to the detection oil passage 135. A pressure detection section 138 that detects the pressure (pilot pressure) of hydraulic oil (pilot oil) flowing through the detection oil path 135 is connected to the detection oil path 135 . The pressure detection unit 138 is a pressure sensor or a pressure switch. Note that a throttle portion 240 is provided in the oil path that connects the detection oil path 135 and the second hydraulic pump P2.

The interlocking valve 230 switches to the communicating position 230c when the first preliminary control valve 56C is at the neutral position 81c, and switches to the communicating position 230a when the first preliminary control valve 56C is at the first position 83a. When the first preliminary control valve 56C is in the second position 83b, it is switched to the communicating position 230b, and when the first preliminary control valve 56C is in the third position 83d, it is switched to the blocking position 230d. In other words, when the first preliminary control valve 56C is switched to the third position 83d, the pilot pressure of the pressure detection unit 138 increases, so that it is detected that the first preliminary control valve 56C is switched to the third position 83d. can do.

The interlock valve 230 may be modified as shown in FIG. 10B. The interlocking valve 230 switches to the cutoff position 230c when the first preliminary control valve 56C is in the neutral position 81c, and switches to the cutoff position 230a when the first preliminary control valve 56C is in the first position 83a. When the first preliminary control valve 56C is in the second position 83b, it is switched to the blocking position 230b, and when the first preliminary control valve 56C is in the third position 83d, it is switched to the communicating position 230d. In other words, when the first preliminary control valve 56C is switched to the third position 83d, the pilot pressure of the pressure detection unit 138 decreases, so that it is detected that the first preliminary control valve 56C is switched to the third position 83d. can do.

As shown in FIG. 11A, the second preliminary control valve 56D in FIG. 4 may be modified. The second preliminary control valve 56D includes a main control valve 190 and a switching valve 191. The main control valve 190 is a two-position switching valve, and is switchable between a first position 190a and a second position 190b. The main control valve 190 is provided with a flow increasing portion 94 at a position corresponding to the first position 190b. The input port 90 of the main control valve 190 is connected to the oil passage 41d, and the third supply/discharge port 104 is connected to the oil passage 107. The oil passage 107 allows hydraulic oil to flow from the main control valve 190 toward the first oil supply/discharge passage 81a, and allows hydraulic oil to flow from the first oil supply/discharge passage 81a toward the main control valve 190. A check valve 195 is provided to prevent this. The switching valve 191 is a valve that switches the main control valve 190, and has an input port side connected to the pilot oil passage 86 via an oil passage 196, and an output port side connected to a pressure receiving part of the main control valve 190. A constriction portion 197 is provided in the oil passage 196 .

The switching valve 191 can be switched between a first position 191a and a second position 191b by a control signal from the control device 88. When the switching valve 191 is switched to the second position 191b, the pilot pressure of the hydraulic oil (pilot oil) in the pilot oil passage 86 acts on the main control valve 190, and the main control valve 190 is switched to the second position 190b. Thereby, the hydraulic oil in the oil passage 41d can be allowed to flow into the oil passage 107 through the main control valve 190 (flow increasing portion 94).

Note that, as shown in FIG. 11B, when the first preliminary control valve 56C is provided with the flow rate reduction part 92 and the internal oil passage 99, the output port 144 side of the main control valve 190 may be connected to the oil passage 76. .
In addition, in FIG. 11A, the second preliminary control valve 56D is configured with a main control valve 190 and a switching valve 191, and the main control valve 190 is switched using pilot oil. As such, the main control valve 190 may be changed to a direct-acting switching valve that is directly switched by an operating member such as a lever.

Further, in FIGS. 11A to 11C, when the boom control valve 56A (boom 10) and the work tool control valve 56B (operating tool) operate, the flow increasing portion 94 of the main control valve 190 is closed. That is, even if there is a command to increase the amount of hydraulic fluid using an operating member such as a switch, the control device 88 will not operate when at least either the boom control valve 56A or the work implement control valve 56B (operating implement) is operated. By switching the switching valve 191 to the first position 191a, the main control valve 190 is switched from the second position 190b to the first position 190a. In addition, when at least either the boom control valve 56A or the work implement control valve 56B (operating tool) is operated, the first preliminary control valve 56C maintains the first position 83a and operates through the flow rate reducing portion 92. supply hydraulic oil to the preliminary attachment.

Furthermore, although the oil passage 196 is connected to the pilot oil passage 86 in FIGS. 11A to 11C, it may be connected to the oil passage 100.
Further, in the embodiment described above, any method may be used to detect that the boom control valve 56A (boom 10) and the work tool control valve 56B (operating tool) are operated. For example, the control device 88 is provided with a state detection device 103. The state detection device 103 is a device that detects at least one of the operations and movements of work tools such as the boom 10 and the bucket 11, and includes an angle sensor that detects the angles of the boom 10 and the bucket 11, and pressures of the pilot valves 59A to 59D. , an expansion/contraction detection sensor that detects expansion and contraction of the boom cylinder 14 and the work implement cylinder 15 , a sensor that detects the operating direction of the operating lever 58 , and the like. The state detection device 103 can detect that the boom control valve 56A (boom 10) and the work tool control valve 56B (operating tool) are operated.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1: Work equipment 10: Boom 11: Work implement 14: Boom cylinder 15: Work implement cylinder 26: Reserve actuator 56: Control valve 56A: Boom control valve 56B: Work implement control valve 56C: First reserve control valve 56D: Second Preliminary control valve 76 : Oil passage 86 : Pilot oil passage 87a : Pressure receiving part 87b : Pressure receiving part 88 : Control device 89 : Operating member 90 : Input port 91 : Output port 92 : Flow rate reduction part 93 : Flow rate increase part 94 : Flow rate increase Part 130 : Interlocking valve 131 : Input port 132 : Output port 135 : Detection oil passage 138 : Pressure detection part 139 : Pressure receiving part 144 : Output port 196 : Oil passage 230 : Interlocking valve

Claims (14)

A variable capacity hydraulic pump that can change the flow rate of hydraulic oil discharged,
multiple hydraulic actuators operated by hydraulic fluid;
a plurality of control valves that can be switched to a plurality of switching positions and that control the flow rate to each of the plurality of hydraulic actuators depending on the switched position among the plurality of switching positions;
Equipped with
The plurality of control valves have an input port into which hydraulic oil discharged from the variable displacement hydraulic pump is input, an output port which outputs the hydraulic oil input to the input port, and a predetermined switching position among the plurality of switching positions. a flow rate reduction part that reduces the hydraulic fluid input to the input port and outputs it to the output port when the flow rate is at a reduction position, which is a switching position;
Among the plurality of control valves, at least one control valve controls hydraulic fluid input to the input port when the control valve is in an increase position that is a switching position different from the predetermined switching position among the plurality of switching positions. comprising a flow rate increase part that outputs more to the output port than the flow rate decrease part ;
The plurality of hydraulic actuators are a boom cylinder, a work tool cylinder, and a backup actuator,
The plurality of control valves are a boom control valve that controls the boom cylinder, a work implement control valve that controls the work implement cylinder, and a first preliminary control valve that controls the preliminary actuator,
The boom control valve and the work implement control valve have the flow rate reduction part,
The first preliminary control valve is a hydraulic system for a working machine, including the flow rate reduction section and the flow rate increase section . If either the boom control valve or the implement control valve is switched to the decrease position while the first reserve control valve is switched to the increase position, the first reserve control valve is switched to the increase position. The working machine hydraulic system according to claim 1, wherein the working machine hydraulic system returns from the reduced position to the reduced position. A variable capacity hydraulic pump that can change the flow rate of hydraulic oil discharged,
multiple hydraulic actuators operated by hydraulic fluid;
a plurality of control valves that can be switched to a plurality of switching positions and that control the flow rate to each of the plurality of hydraulic actuators depending on the switched position among the plurality of switching positions;
Equipped with
The plurality of control valves have an input port into which hydraulic oil discharged from the variable displacement hydraulic pump is input, an output port which outputs the hydraulic oil input to the input port, and a predetermined switching position among the plurality of switching positions. a flow rate reduction part that reduces the hydraulic fluid input to the input port and outputs it to the output port when the flow rate is at a reduction position, which is a switching position;
Among the plurality of control valves, at least one control valve controls hydraulic fluid input to the input port when the control valve is in an increase position that is a switching position different from the predetermined switching position among the plurality of switching positions. comprising a flow rate increase part that outputs more to the output port than the flow rate decrease part;
The plurality of hydraulic actuators are a boom cylinder, a work tool cylinder, and a backup actuator,
The plurality of control valves include a boom control valve that controls the boom cylinder, a work implement control valve that controls the work implement cylinder, a first reserve control valve that controls the reserve actuator, and a first reserve control valve that controls the reserve actuator. a second preliminary control valve ;
The boom control valve, the work implement control valve, and the first preliminary control valve include the flow rate reduction part,
The second preliminary control valve is a hydraulic system for a working machine that includes the flow rate increasing section. comprising an operating member for operating the preliminary actuator,
When the amount of operation of the operation member is less than the threshold value, the first preliminary control valve is switched to the reduced position, and when the amount of operation of the operation member is greater than or equal to the threshold value, the second preliminary control valve is switched to the decrease position. 4. A hydraulic system for a working machine according to claim 3 , wherein the hydraulic system switches to an increasing position. the second preliminary control valve has the flow rate reducing section;
If either the boom control valve or the work implement control valve is switched to the decrease position while the second reserve control valve is switched to the increase position, the second reserve control valve is switched to the increase position. The working machine hydraulic system according to claim 4 , wherein the working machine hydraulic system returns from the reduced position to the reduced position. The first preliminary control valve and the second preliminary control valve have a pressure receiving part on which pilot pressure acts,
The pressure receiving section of the first preliminary control valve and the pressure receiving section of the second preliminary control valve are connected by a pilot oil passage, and the second preliminary control valve is connected to the second preliminary control valve via the pilot oil passage. The hydraulic system for a work machine according to claim 4 or 5 , wherein the hydraulic system for a working machine can be switched to a neutral position among the plurality of switching positions when pressure is applied to the pressure receiving part of the control valve . a detection oil path;
an interlocking valve connected to the detection oil passage and switched according to the plurality of switching positions of the second preliminary control valve;
a pressure detection unit that detects the pilot pressure of the detection oil passage;
Equipped with
The interlocking valve can be switched to a blocking position that blocks pilot oil introduced from the detection oil path to the interlocking valve when the second preliminary control valve switches to the increasing position among the plurality of switching positions. A hydraulic system for a working machine according to any one of claims 3 to 6 . an operating member that operates the preliminary actuator;
a control device that outputs a control signal according to the amount of operation of the operation member;
an operating valve that changes the pilot pressure output according to the control signal of the control device;
Equipped with
The operating valve is connected to either a pressure receiving part of the second preliminary control valve that receives pilot pressure or a pressure receiving part of the linked valve,
When the operation amount of the operating member is equal to or greater than a threshold value, the control device increases the pilot pressure output from the operating valve so that the pilot pressure detected by the pressure detection section becomes equal to or greater than the threshold value. 8. The hydraulic system for a work machine according to claim 7 , wherein the second preliminary control valve is switched to the increase position. When either the boom control valve or the work implement control valve is switched to the decrease position while the second preliminary control valve is switched to the increase position, the control device controls the pilot of the detection oil path. The hydraulic system for a working machine according to claim 8 , wherein the second preliminary control valve is switched to the reduced position by lowering the pilot pressure output from the operating valve so that the pressure becomes less than a threshold value. The control device changes the control signal output to the operating valve, and determines a value of the control signal such that the pilot pressure detected by the pressure detection unit becomes equal to or higher than a threshold value when the control signal is changed. The hydraulic system for a work machine according to claim 8 or 9, wherein the hydraulic system stores information. a detection oil path;
an interlocking valve connected to the detection oil passage and switched according to the plurality of switching positions of the second preliminary control valve;
a pressure detection unit that detects the pilot pressure of the detection oil passage;
Equipped with
The interlocking valve can be switched to a communication position in which pilot oil introduced from the detection oil path to the interlocking valve is communicated when the second preliminary control valve is switched to the increasing position among the plurality of switching positions. A hydraulic system for a working machine according to any one of claims 3 to 6 . an operating member that operates the preliminary actuator;
a control device that outputs a control signal according to the amount of operation of the operation member;
an operating valve that changes the pilot pressure output according to the control signal of the control device;
Equipped with
The operating valve is connected to either a pressure receiving part of the second preliminary control valve that receives pilot pressure or a pressure receiving part of the linked valve,
When the operation amount of the operation member is equal to or greater than a threshold value, the control device lowers the pilot pressure output from the operating valve so that the pilot pressure detected by the pressure detection section becomes less than the threshold value. 12. The hydraulic system for a working machine according to claim 11 , wherein the second preliminary control valve is switched to the increase position. When either the boom control valve or the work implement control valve is switched to the decrease position while the second preliminary control valve is switched to the increase position, the control device controls the pilot of the detection oil path. 13. The hydraulic system for a work machine according to claim 12 , wherein the second preliminary control valve is switched to the reduced position by increasing the pilot pressure output from the operating valve so that the pressure becomes equal to or higher than a threshold value. The control device changes the control signal output to the operating valve, and sets a value of the control signal such that the pilot pressure detected by the pressure detection section becomes less than a threshold value when the control signal is changed. The hydraulic system for a work machine according to claim 12 or 13, wherein the hydraulic system stores information.

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