JP2003004003A - Hydraulic control circuit of hydraulic shovel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to continue multiple operations of an option actuator and a main actuator, despite a simplified and low-cost circuit structure, so as not to cause much variation of speed of the optional devices when the actuators act on the multiple operations. SOLUTION: The present hydraulic control circuit comprises pressure sensors P1 , P2 for detecting the presence and absence of the crusher operation, and restriction means to restrict either or both of a meter-out opening and a meter-in opening of a control valve 9, 11 or the like for controlling a swivel motor 9a of a main control valve block VB and an arm cylinder 11a or the like on the basis of the presence or absence of the detected operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control circuit for a hydraulic excavator to which an optional device such as a crusher can be mounted.

[0002]

2. Description of the Related Art Most of the hydraulic circuit of a hydraulic excavator is a two-pump system having two hydraulic pumps. This hydraulic pump distributes pressure oil to main actuators such as a swing motor, a left and right traveling motor, a boom cylinder, an arm cylinder, and a bucket cylinder, and an optional actuator such as an optional cylinder.

By the way, in recent years, hydraulic excavators have come to be used for dismantling work of buildings, foundations, automobiles, etc. in addition to conventional excavation work. For this dismantling, an optional device called a crusher in which a forked tip can be opened and closed is used instead of the bucket. In that case, the bucket cylinder is used for the forward / backward movement of the crusher, the swing motor is used for the swing operation, and the option cylinder is used for the opening / closing operation of the crusher. It is a composite operation that is operated simultaneously when used. Further, it may be a combined operation with another actuator such as a left and right traveling motor.

[0004]

However, since the hydraulic pump is designed to distribute pressure oil to the main actuators such as the bucket cylinder and the swing motor and the option actuators such as the option cylinder, the hydraulic pump is mainly supplied. When the amount of oil supplied to the actuator increases, the amount of oil supplied to the optional actuator may decrease, and due to the decrease, the opening / closing speed of the crusher becomes slow, which may hinder work efficiency.

On the other hand, a quick movement is desired so that it is said that the open / close speed of the crusher determines the work efficiency, and the operator does not have to move the shovel body so fast, but the speed of the crusher is not required. There was a strong request that I do not want to drop only.

Therefore, a new switching circuit is incorporated in the hydraulic circuit including the control valve, and when the crusher and the arm etc. are operated in combination, the switching circuit is operated to supply the amount of oil supplied to the actuator for opening and closing the crusher. Technology has been developed to increase the
No. 8-41934), the hydraulic circuit is complicated, and it is difficult to reduce the cost by using the existing one. In particular, if the existing control valve cannot be used, the cost of the hydraulic excavator is rather increased. Moreover, since the hydraulic circuit is significantly changed depending on the presence or absence of the optional device, it is difficult to reduce the cost by standardizing the hydraulic circuit.

The present invention has been made in consideration of the problems in the hydraulic control circuit of the conventional hydraulic excavator as described above, and has a simple and inexpensive structure, and has an option when a combined operation of the optional actuator and the main actuator is performed. An object of the present invention is to provide a hydraulic control circuit for a hydraulic excavator that can continue its work without significantly changing the speed of the device.

[0008]

SUMMARY OF THE INVENTION The present invention provides a plurality of main actuators for performing traveling, turning and excavating operations, an optional actuator provided as an option, and a plurality of individual actuators for individually controlling the operation of each of the main actuators. A main control valve block provided with a main control valve, an option control valve for controlling the operation of the optional actuator, a main operating means for operating the main actuator, an optional operating means for operating the optional actuator, and the main An actuator and a plurality of hydraulic pumps as hydraulic sources for the optional actuators are provided, and the discharge oil of each hydraulic pump is distributed and supplied to the main actuator and the optional actuator. In the hydraulic control circuit of the hydraulic excavator configured as described above, when the option actuator is operated, throttling means that throttles the flow rate of the main control valve block to increase the flow rate of the option control valve is provided. It is a feature.

According to the above construction, when the option actuator is operated, the flow rate of the main control valve block is throttled to increase the flow rate of the option control valve. Therefore, for example, when a crusher is used as an optional device. Even if the arm, etc. are operated, the dismantling work is continued without changing the speed of the crusher so much. And in this case,
Since the existing main control valve block can be used, a simple and inexpensive structure can be realized.

A hydraulic control circuit for a hydraulic excavator according to claim 1, further comprising detection means for detecting that the optional operation means is operated, and the throttle means is based on a signal from the detection means. If the flow rate of the optional control valve is increased by narrowing the flow rate of the control valve block (Claim 2), the flow rate of the main control valve block is automatically changed when the option operating means is operated. The flow rate through the option control valve is increased by throttling.

In the hydraulic control circuit of the hydraulic excavator according to claim 1 or 2, the throttle means may be configured to throttle at least one of a meter-in opening and a meter-out opening of the main control valve (claim 3). ,
By narrowing the flow rate of the main control valve, the flow rate of the optional control valve increases relatively.

In the hydraulic control circuit of the hydraulic excavator according to the third aspect, a hydraulic pilot type is used as the main control valve, and the throttle means is configured to reduce the pilot pressure of the main control valve. In this case (claim 4), the existing main control valve block can be used.

According to another aspect of the hydraulic control circuit of the hydraulic excavator of the present invention, the throttle means is configured to reduce the pilot pressure to a value set for each main control valve (claim 5). An appropriate diaphragm action can be obtained according to the type of combined operation of the optional actuator and the main actuator.

According to another aspect of the hydraulic control circuit of the hydraulic excavator of the present invention, the throttle means is configured to reduce the secondary pressure of the pressure reducing valve provided in the pilot line of the main control valve. Claim 6),
At least one of the meter-in opening and the meter-out opening of the main control valve, which is operated by this secondary pressure, is throttled to an opening degree corresponding to the predetermined secondary pressure.

In the hydraulic control circuit for the hydraulic excavator according to claim 4 or 5, if the throttle means is configured to reduce the pressure of the pilot pressure source (claim 7), the pressure reduction amount of the primary pressure is reduced. Since the secondary pressure is also reduced in proportion to, the at least one of the meter-in opening and the meter-out opening of the main control valve operated by this secondary pressure has an opening degree corresponding to the predetermined primary pressure. It is squeezed together.

According to an eighth aspect of the present invention, a plurality of main actuators for performing traveling, turning and excavating operations, optional actuators provided as options, and a plurality of main controls for individually controlling the operation of each of the main actuators. A main control valve block provided with a valve, an option control valve for controlling the operation of the optional actuator, a main operating means for operating the main actuator, an optional operating means for operating the optional actuator, the main actuator and A plurality of hydraulic pumps are provided as hydraulic power sources for the optional actuators, and the oil discharged from each hydraulic pump is distributed and supplied to the main actuators and the optional actuators. In the hydraulic control circuit of the hydraulic excavator configured as described above, the option control valve block including the detection means for detecting that the option operation means is operated, and the option control valve block provided with the option control valve are provided with pressure oil from at least one hydraulic pump. Is provided with a dedicated oil passage that can be supplied to the option control valve, and when the optional operation means is operated, the dedicated oil passage is opened based on a signal from the detection means. It is what

According to the above construction, the option control valve block provided with the option control valve is provided with the dedicated oil passage for supplying the pressure oil from at least one hydraulic pump to the option control valve, and the option operating means is provided. When operated, it is opened based on the signal from the detection means, so when using a crusher as an optional device, for example,
Even if the arm is operated, the dismantling work is continued without changing the speed of the crusher so much. Moreover, in this case, since the standard main control valve block can be used regardless of whether or not the optional device is installed, a simple and inexpensive configuration can be realized.

In the hydraulic control circuit for the hydraulic excavator according to claim 8, left and right traveling hydraulic motors are provided as the main actuators, and at least one hydraulic pressure is applied during a combined operation of the traveling hydraulic motors and other actuators. If it is assumed that a traveling straight-ahead valve that distributes the oil discharged from the pump to both traveling hydraulic motors is provided, and instead of the optional control valve block, a dedicated oil passage is provided in the traveling straight-ahead valve (claim 9), The circuit configuration is further simplified.

In the hydraulic control circuit of the hydraulic excavator according to claim 8 or 9, when the main actuator is not operated, the total flow rate of the hydraulic pump is merged and supplied to the dedicated oil passage (claim 10). ), A sufficient pressure oil supply amount from this dedicated oil passage to the optional actuator is secured.

In the hydraulic control circuit of the hydraulic excavator according to any one of claims 8 to 10, when the main actuator is operated, the flow rate of the main control valve block is restricted so that excess oil is joined to the dedicated oil passage. If it is supplied (claim 11), the securement of the pressure oil supply amount from the dedicated oil passage to the option actuator becomes more reliable.

[0021]

1 is a hydraulic control circuit diagram of a hydraulic excavator according to a first embodiment of the present invention. In FIG. 1, the first hydraulic pump 2, the second hydraulic pump 3, and the operating hydraulic pressure P are driven by driving the engine 1.
The pilot pumps 4 that generate a operate respectively. The first and second hydraulic pumps 2 and 3 are variable displacement hydraulic pumps, and are composed of swash plate type axial piston pumps whose discharge flow rate changes based on the inclination angle displacement of the swash plate.

The pressure oil discharged from the first and second hydraulic pumps 2 and 3 is the center bypass line LCB on the left side of the drawing.
Control valve 5 for moving the right traveling motor 5a, a bucket cylinder control valve 6 for expanding and contracting the bucket cylinder 6a, and a boom cylinder. The pilot type control valve, specifically the left traveling motor 8a, is supplied to the boom cylinder control valve 7 for expanding and contracting the 7a, and is also disposed on the center bypass line RCB on the right side of the drawing. For controlling the left traveling motor, the swing motor control valve 9 for swinging the swing motor 9a, the option cylinder control valve 10 for stretching the option cylinder 10a, and the arm cylinder 11a for stretching. Is supplied to the arm cylinder control valve 11.

The right traveling motor 5a, the bucket cylinder 6a, the boom cylinder 7a, the left traveling motor 8a, the swing motor 9a and the arm cylinder 11a correspond to a main actuator, and the control valves 5 to 9 and 11 thereof correspond to a main control valve. To do. The optional cylinder 10a corresponds to an optional actuator, and the control valve 10 thereof corresponds to an optional control valve.
Further, the control valves 5 to 11 are integrally assembled to form a main control valve block VB. In addition,
This main control valve block VB does not necessarily mean physical unity, but includes a case where the main control valve block VB is arranged in a substantially cohesive form within a compartment.

The option cylinder 10a has an A position which is the first position, an A position which is the second position, and a C position which is the third position, and is normally held at the A position. In the first embodiment, the option cylinder 10a is attached to an option device called a crusher having a bifurcated tip to open and close the option device. Further, since the bucket is removed when the crusher is equipped, the bucket cylinder 6a can be used to move the crusher back and forth, and the turning motor 9a can also be used to turn the crusher.

Oil passage L1 upstream of the right travel motor control valve 5
A straight traveling valve 12 is provided in the vehicle. The traveling straight-ahead valve 12 has a power position which is a first position and a power position which is a second position, and is normally held at the power position.

At this position, the pressure oil discharged from the first hydraulic pump 2 is supplied to the left center bypass line LCB side through the oil passage L1, while the pressure oil discharged from the second hydraulic pump 3 is discharged into the oil passage. It is supplied to the right center bypass line RCB side through L2. Therefore, pressure oil is supplied to the right travel motor control valve 5 and the left travel motor control valve 8 independently of the first hydraulic pump 2 and the second hydraulic pump 3, respectively.

Further, when the left and right traveling levers (not shown) are operated to the same position and the operation valves 31 and 32 as the main operation means are operated by the levers, the operation signal is input to the controller 24. The controller 24 can determine whether or not the operation is being performed based on the presence or absence of the operation signal. Then, the controller 24 gives a command signal to the solenoid proportional valve 22 based on this determination, and the operation of the solenoid proportional valve 22 causes the traveling straight-ahead valve 12 to switch from the power position to the gear position. By switching the traveling straight-ahead valve 12, the pressure oil discharged from the first hydraulic pump 2 is transferred to the oil passage L3.
Through the control valve 9 for the swing motor, the control valve 10 for the optional cylinder, and the control valve 11 for the arm cylinder.

At this time, the pressure oil discharged from the second hydraulic pump 3 flows in parallel to the oil passages L1 and L2 and is supplied to the left and right traveling motor control valves 8 and 5. Thereby,
For example, even when performing a combined operation of hoisting the boom while driving the traveling motors 8a and 5a, the pressure oil discharged from the second hydraulic pump 3 is left and right traveling motors 8a and 5a.
It is supplied equally to 5a and can keep running straightness.

A left cut valve 13 is provided downstream of the boom cylinder control valve 7 in the left center bypass line LCB, while a right center bypass line R is provided.
A right cut valve 14 is provided on the CB on the downstream side of the arm cylinder control valve 11.

The left cut valve 13 is closed when the control valve on the right center bypass line RCB side is operated, while the right cut valve 14 is closed on the left center bypass line LCB.
Operates to close when the side control valve is operated.
In other words, when the straight travel valve 12 is switched to the positive position, the pressure oil discharged from the second hydraulic pump 3 is shunted to the oil passages L1 and L2, so that any control on the right center bypass line RCB side is performed. This is because when the valve is operated, the pump pressure cannot be established unless the left cut valve 13 on the left center bypass line LCB side is closed.
This is because the pump pressure cannot be established unless the right cut valve 14 on the right center bypass line RCB side is closed when operating any control valve on the left center bypass line LCB side.

Further, the oil passage L3 is connected at a joining point P to a joining oil passage L4 branched from the downstream side of the left travel motor control valve 8 in the right center bypass line RCB,
Pressure oil is supplied to the option cylinder control valve 10 through an oil passage L5 extending from the confluence point P, and pressure oil is supplied to the arm cylinder control valve 11 through oil passages L6 and L7 extending from the confluence point P. Supplied.

The control valve 10 for the option cylinder can change the spool by operating a pedal 30 as an option operating means. That is, when the pedal 30 is not operated, the control valve 10 for the option cylinder is in the a position, so it is not connected to the option cylinder 10a, but when the pedal 30 is operated in the direction A in FIG. Switch to position. Then, the pressure oil discharged from one of the first and second hydraulic pumps 2 and 3 is supplied to the head side oil chamber of the option cylinder 10a to extend the rod, so that the tip of the crusher is opened. be able to. On the other hand, pedal 3
When 0 is operated in the B direction in FIG. 1, the option cylinder control valve 10 switches to the c position. Then, the pressure oil discharged from one of the first and second hydraulic pumps 2 and 3 is supplied to the rod-side oil chamber of the option cylinder 10a to shrink the rod, so that the tip of the crusher is closed. be able to. In this way, the first embodiment
Then, the opening / closing operation of the crusher can be easily performed only by operating the pedal 30.

Incidentally, 15, 1 in the oil passages L3 to L7
6, 26 and 27 are check valves. In FIG. 1, reference numeral 17 is an arm pushing merge valve for accelerating arm pushing,
Similarly, reference numeral 18 is a boom raising merge valve for accelerating the boom raising. In addition, the outlet lines L8 and L9 of the left and right cut valves 13 and 14 are respectively return lines L1.
0 and L11 are joined and connected to the tank 20 via an oil cooler 19. In FIG. 1, reference numeral 21 is a check valve with a spring whose opening pressure is set according to the maximum hydraulic pressure of this circuit. Similarly, 23 and 25 are solenoid proportional valves controlled by a command signal from the controller 24.

In the first embodiment, further, pressure sensors P1 and P2 as detecting means for detecting the presence or absence of the crusher operation by the pedal 30, and the pressure sensors P1 and P1.
Detected pressure of P2 (hereinafter referred to as crusher operating pressure)
When it is detected that there is a crusher operation, the bucket cylinder control valve 6, the boom cylinder control valve 7, the swing motor control valve 9 and the arm used in association with the operation of the option cylinder control valve 10. A throttle means for narrowing at least one of the meter-in opening and the meter-out opening of the cylinder control valve 11 is provided. Although the option cylinder control valve 10 and the left and right traveling motors 8 and 5 which are often used without being related to the operation of the option cylinder control valve 10, are excluded from the target of the throttle means here. Alternatively, it may be a target of the diaphragm means.

This throttle means reduces the secondary pressure of the operation valve 31 for operating the bucket cylinder control valve 6 and the boom cylinder control valve 7 when the above crusher operation is performed. And the electromagnetic proportional valves 321 to 324 for reducing the secondary pressure of the operation valve 32 for operating the swing motor control valve 9 and the arm cylinder control valve 11 when the crusher operation is performed, and the operation valve 31. Pressure sensors P311 to P314 for detecting the secondary pressure for the primary pressure control, and pressure sensors P321 for detecting the secondary pressure for the primary pressure control of the operation valve 32.
P324 and. In addition, the solenoid proportional valves 311-3
The secondary pressures 14, 321 to 324 can be individually set according to the longitudinal movement of the boom, arm, crusher, and the like. Further, the solenoid proportional valves 311 to 314, 32
Although not clearly shown in the figure, 1 to 324 are made up of blocks having an integral structure to make them compact.

Further, as shown in FIG. 2, the operation valves 31, 3 are
A pressure reducing valve 41 and a lever lock solenoid valve 42 for reducing the primary pressure of 2 when the crusher operation is performed are provided. In the combination of the pressure reducing valve 41 and the lever lock solenoid valve 42, an oil passage as shown in FIG. 2 is usually formed, and the operation valves 31, 32 are in a state where no primary pressure is applied.

The primary pressure by adjusting the opening of the pressure reducing valve 41, that is, the primary pressure reducing amount of the operating valves 31, 32 is 50% in the combined operation of the crusher and the boom raising,
No pressure reduction if combined operation of crusher and boom lowering, 6 if combined operation of crusher and arm pull
0%, 40% for combined movement of crusher and arm pushing, 30% for combined movement of crusher and turning
It is set individually in advance depending on the type of work, such as reducing the pressure to%.

When the detection signals from the pressure sensors P1 and P2 indicating the operation of the pedal 30 are taken into the controller 24, a command signal is issued from the controller 24 to the lever lock solenoid valve 42, and the shut-off lever is operated by this command signal. When operated, the port of the lever lock solenoid valve 42 is switched. Then, the pilot pressure Pa is reduced to the predetermined primary pressure by the pressure reducing valve 41, and the operation valve 31,
It is taken in by 32 and is further decompressed individually on the secondary pressure lines of the operation valves 31, 32, and acts on each control valve. On the secondary pressure lines of these operation valves 31, 32,
As described above, the pressure sensors P311 to P314, P3
Since 21 to P324 are installed, the detection signal thereof is also fetched by the controller 24. Then, the controller 24 gives a command signal proportional to the signal level to the pressure reducing valve 41, whereby feedback control of the pressure reducing valve 41 is performed.

The method of controlling the primary pressure of the operating valves 31, 32 is not limited to this, and the lever lock solenoid valve 42 is omitted and the pressure reducing valve 43 is directly operated by a command signal from the controller 24. Alternatively, instead of the electromagnetic proportional pressure reducing valves 41 and 43, as shown in FIG. 4, a manually operated proportional valve 44 may be used.
And a switching valve 45 in combination (see FIG. 4),
Alternatively, the switching valve 45 and the throttle valve 46 may be used in combination (see FIG. 5). In both cases, the same pressure reducing action as in the case where the pressure reducing valve 41 and the lever lock solenoid valve 42 are combined is obtained.

As described above, the opening / closing operation of the crusher is performed by the option cylinder 10a, and
When the boom cylinder 6a and the swing motor 9a perform the forward and backward movements of the crusher and the swing operation, according to the first embodiment, the presence / absence of the crusher operation is detected. Since at least one of the meter-in opening and the meter-out opening of the cylinder control valve 6 and the swing motor control valve 9 is throttled, the pressure oil supply amount to the bucket cylinder 6a, the swing motor 9a, etc. is reduced by this throttle amount. However, since the option cylinder control valve 10 side is not throttled, the pressure oil supply amount to the option cylinder 10a hardly decreases. Therefore, when the crusher is used, even if the shovel body is operated, the dismantling work is continued without changing the speed of the crusher so much. Therefore,
The work efficiency is improved because the work is comfortable and quick. Moreover, in this case, since the existing main control valve block VB can be used, a simple and inexpensive structure is realized.

On the secondary pressure line of the operation valve 31, as shown in FIG. 6, instead of the electromagnetic proportional valves 311-314, throttle valves 311a-314a, 311b-314b are provided.
It is also possible to provide a pressure reducing circuit in which the switching valve 315 and the switching valve 315 are combined so that the pressure can be reduced collectively.

Further, on the secondary pressure line of the operation valve 31,
As shown in FIG. 7, a switching valve 316 operated by the crusher operating pressure detected by the pressure sensors P1 and P2 may be provided so that the throttle action by the solenoid proportional valve 312 or the like does not work when the crusher is not operated. . Operation valve 32
The secondary pressure line can also have the same configuration as described above.

Further, in the above throttle means, the operation valves 31, 3 are
Although the pilot pressure is reduced by throttling both the primary pressure and the secondary pressure of 2, the at least one may be throttled. Further, when reducing the secondary pressure, at least one of the meter-in opening and the meter-out opening may be reduced.

By the way, when the work spools of the control valves 6, 7, 9 and 11 are held during the stroke, it is necessary to prevent pressure loss from the center bypasses LCB and RCB. For this reason, in the above description, the left and right cut valves 13, 14 are used to close the center bypasses LCB, RCB, but instead, as check valves 16, 26, 27, as shown in FIG. A check valve may be used.

Further, in the above-mentioned throttle means, the operation valves 31, 3 are
By reducing the primary pressure and the secondary pressure of 2, the control valve 6,
The meter-in and meter-out openings of 7, 9 and 11 are indirectly throttled, but it is also possible to directly throttle the meter-in and meter-out openings as long as the main control valve block VB is not complicated. Good. The present modification is made in view of this point, and FIGS. 9 and 10 show a partial hydraulic pressure control circuit thereof.

Here, as shown in FIG. 9 and FIG.
A throttle valve 317 is provided on at least one of the meter inline and the meter outline of each of the control valves 11 and 9 of the arm cylinder 11a and the swing motor 9a that have a pressure lower than the operating pressure of the crusher. We are going to narrow down 317. This throttle valve 31
Reference numeral 7 concretely narrows the opening of the load check valve provided in front of the spool. However, when it is desired to adjust the closing amount individually in the arm and swing circuits, the load check valve is opened and closed. It is possible to directly detect the crusher operating pressure and open / close the load check valve according to the detected value, but in the case of arm pushing operation, it does not close, so only arm pulling or turning operation, or opening. The electromagnetic proportional valves 311 to 314 and 321 to 324 of the first embodiment may be used to adjust the degree.

Further, as the squeezing means, a sub-spool (not shown) contained in the spool may be squeezed, or in the case of arm meter-out, a reproduction spool 318 may be used as shown in FIG. Here, if only the meter-in side is narrowed down, cavitation occurs, so it is preferable to narrow down the meter-in side and the meter-out side at the same time, or to narrow down only the meter-out side.

(Second Embodiment) FIG. 11 shows a hydraulic control circuit of a hydraulic excavator according to a second embodiment of the present invention. The same elements as those in the first embodiment are designated by the same reference numerals, and duplicate description thereof will be omitted.

In the second embodiment, as shown in FIG. 11, pressure lines L51 and L52 as detecting means for detecting the presence or absence of the crusher operation and at least one of the first and second hydraulic pumps 2 and 3 are used. And a switching valve 50 that opens and closes the dedicated oil passage L50 according to the presence or absence of the detected operation. There is.

Then, except for a machine such as a crusher which requires an optional device, the optional control valve block VB including the switching valve 50 and the optional cylinder control valve 10 is provided so that the switching valve 50 need not be mounted.
X is a so-called ADD-ON system that can be appropriately mounted on the main control valve block VBY including other control valves 5 to 9 and 11.

The switching valve 50 has a service position as the first position and a drive position as the second position, and is normally in the service position. However, when operating the crusher, the pedal 30 is operated.
By this operation, the switching valve 50 is switched to the shift position by the pilot pressure from the pressure lines L51 and L52.

However, when the actuators 5a-9a, 11a of the shovel body are not operated at the same time, the total flow rates of the first and second hydraulic pumps 2, 3 are merged and supplied to the dedicated oil passage L50 of the switching valve 50. Then, pressure oil is supplied from the dedicated oil passage L50 to the option cylinder 10a via the option cylinder control valve 10.

On the other hand, when operating the actuators 5a to 9a, 11a of the shovel body, the control valve 5 is operated.
~ 9,11 to limit the supply flow rate to the excess oil switching valve 5
No. 0 dedicated oil passage L50 is joined and supplied, and the option cylinder control valve 10 is supplied from this dedicated oil passage L50.
Pressure oil is supplied to the option cylinder 10a via the. For this purpose, a throttle valve 51 and a flow controller 52 that adjusts the flow rate according to the operating pressure of the pedal 30 are provided downstream of the switching valve 50. However, the flow controller 52 can be omitted by using a throttle valve with a flow rate adjusting function.

According to the second embodiment, the presence / absence of the crusher operation is detected, and depending on the presence / absence of the operation, the crusher is connected to the option cylinder 10a and at least one of the first and second hydraulic pumps 2 and 3 is connected. Since the dedicated oil passage L50 of the switching valve 50 capable of supplying the pressure oil from is opened and closed, the dedicated oil passage L50 should be opened in addition to the oil passage distributed and supplied from the hydraulic pump at the time of crusher operation. As a result, the amount of pressure oil supplied to the option cylinder control valve 10 is secured. Therefore, when the crusher is used, even if the shovel body is operated, the dismantling work is continued without changing the speed of the crusher so much.
Therefore, the work can be performed comfortably and quickly, and the work efficiency is improved. Moreover, in this case, since the standard main control valve block VBY can be used regardless of whether or not the optional device is installed, a simple and inexpensive configuration can be realized.

(Third Embodiment) FIG. 12 shows a hydraulic control circuit of a hydraulic excavator according to a third embodiment of the present invention. The elements common to those in the first and second embodiments are designated by the same reference numerals, and duplicate description thereof will be omitted.

In the third embodiment, as shown in FIG.
Since the dedicated oil passage L60 is incorporated in the traveling straight-ahead valve 60 arranged in the main control valve block VBZ, the option control valve block VBX having a single switching valve as in the second embodiment is not provided.

The traveling straight-ahead valve 60 has a ta position as a first position, a chi position as a second position, and a toe position as a third position, and is normally at the ta position. When the controller 24 determines from the crusher operation pressure that there is a crusher operation, it gives a command signal to the solenoid proportional valve 61, and operates the solenoid proportional valve 61 by this command signal.
By switching the straight travel valve 60 to the C position, and further to the T position, the predetermined flow rate control as described in the second embodiment can be performed.

That is, when the crusher is operated, the travel straight valve 60 is switched to the to position by the operation of the pedal 30, but at the same time when the actuators 5a-9a, 11a of the shovel body are not operated, the first and second actuators are operated. All the flow rates of the hydraulic pumps 2 and 3 are merged and supplied to the dedicated oil passage L60 of the straight-travel valve 60, and the pressure oil from the dedicated oil passage L60 to the option cylinder 10a via the option cylinder control valve 10 is supplied. Supply will begin.

On the other hand, when operating the actuators 5a to 9a, 11a of the shovel body, the control valve 5 is operated.
By limiting the supply flow rates to 9 and 11, the surplus oil is joined to the dedicated oil passage L60 of the straight-travel valve 60 and supplied.
Control valve for optional cylinder 1 from this dedicated oil passage L60
Pressure oil is supplied to the option cylinder 10a via 0. For this purpose, a throttle valve 62 and a flow controller 63 that adjusts the flow rate according to the operating pressure of the pedal 30 are provided on the downstream side of the straight travel valve 60.

However, the flow controller 62 is
The operation pressure of the pedal 30 is detected by the pressure sensor 64, the electromagnetic proportional valve 65 is operated by the command signal from the controller 24 according to the detected pressure, and the flow rate is adjusted within the setting range by the limiting flow rate controller 66. I am supposed to do it.

According to the third embodiment, in addition to the same effects as the second embodiment, a single switching valve like the switching valve 50 of the second embodiment is not required, so that the circuit configuration is simplified. There is an advantage that Therefore, the circuit configuration of a particularly small construction machine becomes easy.

Although the option cylinder control valve 10 is provided in parallel with the other control valves in the first embodiment, the option cylinder control valve 10 is configured in series as in the second and third embodiments. Alternatively, it may be provided upstream of another control valve. In this way, the influence of bleed-off from the work spool of the other control valve can be reliably eliminated. Further, in the above-described first to third embodiments, the crusher has been described as the optional device, but the applicable range of the present invention is not limited to this, and the present invention can be similarly applied to other optional devices such as a grapp.

[0063]

According to the present invention, for example, when a crusher is used as an optional device, even if the arm or the like is operated, the dismantling work can be continued without changing the speed of the crusher so much. Moreover, in this case, since the existing main control valve block can be used, a simple and inexpensive structure can be realized.

According to the invention described in claims 2 and 3,
By narrowing the flow rate of the main control valve, the flow rate of the optional control valve can be relatively increased.

According to the invention described in claims 4 to 7, an appropriate throttling action can be obtained, and since the existing main control valve block can be used, the manufacturing cost can be reduced.

According to the invention described in claim 9, the circuit configuration is further simplified. Therefore, the circuit configuration of a particularly small construction machine becomes easy.

According to the tenth and eleventh aspects of the present invention, a sufficient pressure oil supply amount from the dedicated oil passage to the option actuator is secured.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic excavator according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a first example of control on the primary pressure side of an operation valve.

FIG. 3 is an explanatory diagram showing a second example of control on the primary pressure side of the operation valve.

FIG. 4 is an explanatory diagram showing a third example of control on the primary pressure side of the operation valve.

FIG. 5 is an explanatory diagram showing a fourth example of control on the primary pressure side of the operation valve.

FIG. 6 is an explanatory diagram showing a first example of control on the secondary pressure side of the operation valve.

FIG. 7 is an explanatory diagram showing a second example of control on the secondary pressure side of the operation valve.

FIG. 8 is an explanatory diagram showing an example of control by a load check valve.

FIG. 9 is a partial hydraulic circuit diagram of a hydraulic excavator according to a modification.

FIG. 10 is a partial hydraulic circuit diagram of a hydraulic excavator according to a modification.

FIG. 11 is a hydraulic circuit diagram of the hydraulic excavator according to the second embodiment of the present invention.

FIG. 12 is a hydraulic circuit diagram of a hydraulic excavator according to a third embodiment of the present invention.

[Explanation of symbols]

2 First hydraulic pump 3 Second hydraulic pump 5 Right travel motor control valve (main control valve) 5a Right travel motor (main actuator) 6 Bucket cylinder control valve (main control valve) 6a Bucket cylinder (main actuator) 7 Boom Cylinder control valve (main control valve) 7a Boom cylinder (main actuator) 8 Left travel motor control valve (main control valve) 8a Left travel motor (main actuator) 9 Swing motor control valve (main control valve) 9a Swing motor (Main actuator) 10 Control valve for optional cylinder (optional control valve) 10a Optional cylinder (optional actuator) 11 Control valve for arm cylinder (main controller) Valve) 11a Arm cylinder (main actuator) 12 Traveling linear valve 24 Controller (throttle means) 30 Pedal (optional operation means) 31, 32 Operation valve (main operation means) 311 to 314, 321 to 324 Pressure reducing valve (throttle means) 41 Pressure reducing valve (throttle means) 50 Switch valve 51 Throttle valve 52 Flow controller 60 Traveling straight valve 61 Electromagnetic proportional valve 62 Throttle valve 63 Flow controller P1, P2 Pressure sensor (detection means) L50, L60 Dedicated oil passage VB, VBY, VBZ main Control valve block VBX Option control valve block

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2D003 AA01 AB01 AB02 AB03 AB04                       BA02 BB02 BB03 CA03 CA09                       DA03 DB02                 3H089 AA22 AA23 AA60 AA72 AA73                       AA74 BB20 CC01 CC08 DA03                       DA06 DB01 DB13 DB47 DB49                       DB63 EE05 EE07 FF05 GG02                       HH05 JJ02

Claims (11)

[Claims] 1. A main provided with a plurality of main actuators for performing traveling, turning and excavating operations, an optional actuator provided as an option, and a plurality of main control valves for individually controlling the operation of each of the main actuators. A control valve block, an option control valve for controlling the operation of the optional actuator, a main operating means for operating the main actuator, an optional operating means for operating the optional actuator, a hydraulic source for the main actuator and the optional actuator. Hydraulic excavator having a plurality of hydraulic pumps, and configured to distribute the oil discharged from each hydraulic pump to the main actuator and the optional actuator. In the hydraulic control circuit of the hydraulic excavator, when the option actuator is operated, throttling means for throttling the flow rate of the main control valve block to increase the flow rate of the option control valve is provided. Hydraulic control circuit. 2. The hydraulic control circuit for a hydraulic excavator according to claim 1, further comprising a detection means for detecting that the optional operation means is operated, and the throttle means is based on a signal from the detection means. A hydraulic control circuit for a hydraulic excavator, wherein the flow rate of the optional control valve is increased by reducing the flow rate of the main control valve block. 3. The hydraulic excavator hydraulic control circuit according to claim 1, wherein the throttle means is configured to throttle at least one of a meter-in opening and a meter-out opening of the main control valve. Hydraulic control circuit. 4. The hydraulic control circuit for a hydraulic excavator according to claim 3, wherein a hydraulic pilot type is used as the main control valve, and the throttle means is configured to reduce the pilot pressure of the main control valve. The hydraulic control circuit of the hydraulic excavator. 5. The hydraulic excavator hydraulic control circuit according to claim 4, wherein the throttle means is configured to reduce the pilot pressure to a value set for each main control valve. Hydraulic control circuit. 6. The hydraulic control circuit for a hydraulic excavator according to claim 4, wherein the throttle means is configured to reduce the secondary pressure of the pressure reducing valve provided in the pilot line of the main control valve. Hydraulic control circuit for hydraulic excavator. 7. The hydraulic control circuit for a hydraulic excavator according to claim 4 or 5, wherein the throttle means is configured to reduce the pressure of the pilot pressure source. 8. A main provided with a plurality of main actuators for performing traveling, turning and excavating operations, an optional actuator provided as an option, and a plurality of main control valves for individually controlling the operation of each of the main actuators. A control valve block, an option control valve for controlling the operation of the optional actuator, a main operating means for operating the main actuator, an optional operating means for operating the optional actuator, a hydraulic source for the main actuator and the optional actuator. Hydraulic excavator having a plurality of hydraulic pumps, and configured to distribute the oil discharged from each hydraulic pump to the main actuator and the optional actuator. In the hydraulic control circuit of the device, an option control valve block equipped with a detection means for detecting that the option operation means has been operated, and an option control valve block,
A dedicated oil passage capable of supplying pressure oil from at least one hydraulic pump to the optional control valve is provided, and when the optional operation means is operated, the dedicated oil passage is opened based on the signal from the detection means. A hydraulic control circuit for a hydraulic excavator, which is configured to be opened. 9. The hydraulic control circuit for a hydraulic excavator according to claim 8, wherein left and right traveling hydraulic motors are provided as the main actuators, and at least 1 is set during combined operation of the traveling hydraulic motors and other actuators. A travel straight valve is provided that distributes the oil discharged from one hydraulic pump to both travel hydraulic motors, and instead of the optional control valve block, a dedicated oil passage is provided in this travel straight valve for a hydraulic excavator. Hydraulic control circuit. 10. The hydraulic control circuit for a hydraulic excavator according to claim 8 or 9, wherein when the main actuator is not operating, the entire flow rate of the hydraulic pump is joined and supplied to the dedicated oil passage. Excavator hydraulic control circuit. 11. A hydraulic control circuit for a hydraulic excavator according to any one of claims 8 to 10, wherein when the main actuator is operated, a flow rate of passage through a main control valve block is limited, and excess oil is supplied to the dedicated oil passage. A hydraulic control circuit for a hydraulic excavator, characterized in that the hydraulic power is merged and supplied.