JP3097973B2 - Hydraulic working machine hydraulic circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit of a hydraulic working machine such as a hydraulic shovel having a plurality of actuators and capable of compoundly driving these actuators.

[0002]

2. Description of the Related Art FIGS. 8 and 9 show a first prior art of this kind.
FIG. 8 is a circuit diagram showing a configuration of the first example, and FIG. 9 is a cross-sectional view showing a flow control means and a second directional control valve portion provided in the first example shown in FIG. FIG. These first examples of the prior art correspond to the technique described in Japanese Patent Publication No. 62-25827.

[0003] A first example of the prior art shown in FIG. 8 is a first directional switching valve of a plurality of directional switching valves connected to a discharge pipe b of a hydraulic power source 2, for example, a turning directional switching valve 21. The first is controlled to be driven by the turning direction switching valve 21.
, A swing motor 50, a second direction switching valve, for example, an arm direction switching valve 23, and a second actuator whose driving is controlled by the arm direction switching valve 23, ie, an arm cylinder 40. ing.

The turning direction switching valve 21 connects the hydraulic power source 2 to the tank port 100 when the turning direction switching valve 21 is in a neutral state, and has a center bypass passage 110 whose opening area changes so as to become smaller in accordance with the operation amount of the turning direction switching valve 21. Similarly, the arm direction switching valve 23 also connects the hydraulic pressure source 2 to the tank port 100 when the arm is in the neutral state and changes the opening area in accordance with the operation amount of the arm direction switching valve 23 so that the opening area decreases. It has a bypass passage 120.

The arm direction switching valve 23 is connected to the downstream portion r of the center bypass passage 110 of the turning direction switching valve 21, and connects the input port 111 of the turning direction switching valve 21 to the parallel pipe z. A first input port 121 connected to the hydraulic pressure source 2 in parallel through the
Of the second input port 1 connected to the hydraulic power source 2 from the downstream portion r of the center bypass passage 110 through the first check valve f
22. The above-mentioned parallel conduit z and the second input port 122 are connected to each other via a second check valve 123 and a fixed throttle G which is a flow control means.

When the arm directional control valve 23 is switched to the position 23a, the second input port 122
The meter-in second output port 130a is connected to the pipeline t for supplying pressure oil to the bottom side of the arm cylinder 40, and the first input port 121 is used when the arm direction switching valve 23 is switched to the position 23b. , The first output port 130b of the meter-in
Is connected to a pipeline s for supplying pressure oil to the rod side of.

Reference numeral 403 denotes a turning pilot valve for operating the turning direction switching valve 21; 404, an arm pilot valve for operating the arm direction switching valve 23;
Reference numeral 1 denotes a pilot hydraulic pressure source for supplying pressure oil to the turning pilot valve 403 and the arm pilot valve 404;
02 is a pilot relief valve that regulates the pressure of the pressure oil discharged from the pilot hydraulic pressure source 401. 410a is for switching the pilot pressure generated by the arm pilot valve 404 to the position 23a of the arm direction switching valve 23. A pilot line 410b is a pilot line for guiding the pilot pressure generated by the arm pilot valve 404 for switching the arm direction switching valve 23 to the position 23b.

The fixed throttle G and the arm direction switching valve 23 are formed, for example, in a valve structure as shown in FIG.

In FIG. 9, 2 is a hydraulic pressure source, 100 is a tank port, r is a downstream portion of the turning direction switching valve 21,
z is a parallel line, f is a first check valve, 123 is a second check valve, G is a fixed throttle, 121 and 122 are first input ports of the arm direction switching valve 23, and second input. Port, 1
Reference numerals 24a and 124b denote passages built in the switching positions 23a and 23b of the arm direction switching valve 23, respectively.
Reference numeral 130b denotes a second output port and a first output port of the arm direction switching valve 23, which are shown in FIG.
Is equivalent to

[0010] Of these, the downstream portion r of the turning direction switching valve 21, the parallel pipe z, the first check valve f, the second check valve 123, the first input port 121, and the second input port. 1
22, passages 124a, 124b, first output port 13
0b, the second output port 130a is
0, and in particular, the first check valve f and the second check valve 123 are slidably formed, and the first check valve f is provided on the downstream side of the seat surface of the first check valve f. A first check passage 151 is provided so as to be built in the first check valve f, and the second check valve 12 is provided downstream of the seat surface of the second check valve 123.
3, a second check passage 152 is provided.

Further, a plate 150 is provided integrally with the casing main body 200 by bolts 201, and a pipe 153 communicating with the first check passage 151 and the second check passage 152 is formed in the plate 150. The fixed stop G described above is provided in the conduit 153.

The operation of the first example of the prior art having the above-mentioned configuration is as follows.

(1) Operation of the arm alone (a) When the directional control valve 23 for the arm is operated to the position 23a side By operating the arm pilot valve 404 shown in FIG. When the directional control valve 23 is operated to switch to the position 23a,
The pressure oil of the hydraulic pressure source 2 is diverted through the discharge pipe b, and a part of the pressure oil passes through the center bypass passage 110 and the downstream portion r to open the first check valve f and to the second input port 122. Reach.
The remaining pressure oil resulting from the above-mentioned split flow opens the second check valve 123 through the parallel conduit z, and reaches the second input port 122 through the fixed throttle G. In this way, the pressure oil joined at the second input port 122 flows into the pot side of the arm cylinder 40 through the passage 124a and the pipe t, and extends the arm cylinder 40 to cloud an arm (not shown). The pressure oil on the rod side of the arm cylinder 40 is returned to the tank through the pipe s. Since the flow rate of the pressure oil of the hydraulic pressure source 2 passing through the fixed throttle G is small, the pressure loss here is small.

(B) Move the arm direction switching valve 23 to the position 23
When the arm directional switch valve 23 is operated to switch to the position 23b by operating the arm pilot valve 404 shown in FIG. The oil reaches the first input port 121 via the discharge line b, the parallel line z, and the second check valve 123, passes through the passage 124b of the arm direction switching valve 23, and the rod of the arm cylinder 40 via the line s. Side, the arm cylinder 40 is contracted, and the arm (not shown) is dumped.
The pressure oil on the bottom side of the arm cylinder 40 is returned to the tank through the pipe t. At this time, since the pressure oil does not pass through the throttle at all, the pressure loss in the circuit is small.

(2) Combined operation of arm and swing (a) The arm direction switching valve 23 is switched to the position 23a, and at the same time, the swing pilot valve 403 is operated to move the swing direction switching valve 21 up or down in FIG. Is switched to the switching position, the hydraulic oil of the hydraulic power source 2 passes through the discharge pipe b, and a part thereof is supplied to the turning motor 50 through the input port 111 and the turning direction switching valve 21. The remaining pressure oil is supplied to the bottom side of the arm cylinder 40 via the parallel pipe z, the second check valve 123, the fixed throttle G, the passage 124a of the arm direction switching valve 23, and the pipe t. At this time, even if the load on the arm (not shown) is low due to the function of the fixed throttle G, the pressure in the parallel conduit z can be secured sufficiently high to rotate the turning motor 50, so that the turning motor 50 is driven at a predetermined speed. It is possible to realize rotation of the rotating body (not shown) by rotating, and at the same time, it is possible to realize cloud of an arm (not shown). (B) Directional switching valve for arm 2
When the turning direction switching valve 21 is switched to one of the upper and lower switching positions in FIG. 8 by operating the turning pilot valve 403 and simultaneously turning the turning pilot valve 403, the pressure oil of the hydraulic power source 2 causes the discharge pipe b to move. Yes, some of them are input ports 111,
It is supplied to the turning motor 50 via the turning direction switching valve 21. The remaining pressure oil is in the parallel line z, the second check valve 12
3. First input port 121, directional control valve for arm 23
Is supplied to the rod side of the arm cylinder 40 through the passage 124b and the pipe s. As a result, the arm (not shown) dumps, but the load at this time is generally sufficiently large, the pressure in the parallel pipe z is high, and the swing motor 5
0 rotates at a predetermined speed. In this case, since the pressure oil does not pass through the throttle at all, the pressure loss in the circuit is small.

As described above, in the first example of the prior art shown in FIGS. 8 and 9, during operations other than simultaneous turning of the cloud of the arm (not shown) and the swinging body (not shown),
Since the pressure loss of the circuit can be reduced, the temperature rise of the circuit and the deterioration of the fuel consumption rate of the prime mover (not shown) that drives the hydraulic power source 2 are prevented.

However, in the first example of the prior art, the fixed diaphragm G built in the plate member 150
Is set, that is, set uniquely, so that, for example, in order to extend the range of work performed via an arm (not shown), an arm having a standard length is provided instead. For example, when the arm cylinder 40 is replaced with a long arm having a longer length, the load of the heavy object driven by the arm cylinder 40 increases, and the pipeline t in the arm cloud operation in which the arm cylinder 40 operates to extend.
Supply pressure decreases. For this reason, the supply pressure of the hydraulic power source 2 in the simultaneous operation of the swing motor 50 and the arm cylinder 40 at the time of the arm cloud decreases, and accordingly, the fixed throttle G set by the standard arm as described above. If the characteristics remain unchanged, the supply pressure supplied to the swing motor 50 when the long arm is mounted decreases, and the desired acceleration of the swing body (not shown) cannot be obtained. As described above, when the attachment to be mounted is replaced with a conventional one, the optimum aperture characteristic may not be obtained.

Simultaneously with the excavation work performed through the arm cloud operation, which is normally performed by a hydraulic excavator, the amount of operation of the turning direction switching valve 21 is increased until the center bypass passage 110 is shut off. In the swing pressing excavation operation in which the swing body is swiveled, the swing force of the swing body is determined by the characteristics of the fixed throttle G. If the opening area of the fixed aperture G is set smaller, the turning force at the time of turning pressing excavation increases. However, the fixed aperture G
As the opening area of the arm is made smaller, the arm speed at the time of compounding is further reduced, which leads to a situation in which the working efficiency is reduced. Thus, in the first example of the related art, turning,
During the arm combined operation, it has been difficult to obtain a desired throttle characteristic according to the working conditions of the hydraulic excavator and the lever operation amount for operating the direction switching valve.

Further, in the first example of the prior art, when the arm dump is performed in the free descent direction in the combined operation of the turning operation and the arm dump operation, the load pressure of the arm cylinder 40 is low. As a result, sufficient pressure oil cannot be supplied to the turning motor 50, and a desired acceleration of the turning operation cannot be obtained.

Conventionally, the following second example has been proposed as a technique capable of solving some of the problems in the first example shown in FIGS. 8 and 9 described above.
This second example corresponds to the technique described in Japanese Utility Model Publication No. 3-52272.

FIG. 10 is a circuit diagram showing a configuration of a second example of the above-mentioned prior art. The second example is different from the first example shown in FIGS. 8 and 9 in that the first example does not include the first check valve f and the fixed throttle G in the first example. A turning priority valve 48 is provided as a flow control means capable of adjusting the throttle characteristic at a position upstream of the second check valve 123 in the pipe z, and adjustment for adjusting the throttle characteristic of the turning priority valve 48 is performed. An operation amount detecting means provided as a means for extracting a pilot pressure corresponding to the operation amount of the turning pilot valve 403 and supplying the pilot pressure to the turning priority valve 48 as a drive signal, that is, a shuttle valve 405 is provided.

In the second example of the prior art, the shuttle valve 4 is operated in accordance with the operation of the turning pilot valve 403.
Since the opening area of the turning priority valve 48 is controlled to be small in accordance with the pilot pressure taken out from the turning valve 05, the turning direction switching valve 21 is turned by the turning priority valve 48 during the combined operation of the turning and the arm. Thus, a part of the problem in the first example shown in FIGS. 8 and 9 can be solved.

[0023]

However, in the second example shown in FIG. 10, the arm cylinder 4 which is the second actuator is used for turning and combining the arms.
Swiveling priority valve 4 at arm cloud when load pressure of 0 is low
8 is equal to the opening area of the turning priority valve 48 at the time of arm dumping where the load pressure of the arm cylinder 40 is relatively high, for example, acceleration of turning when the arm cloud is combined with a low load pressure of the arm cylinder 40 When the opening area of the swing priority valve 48 is set in consideration of supplying a desired pressure oil to the swing motor 50 as the first actuator so as to improve the performance, the arm cylinder 40 with a high load pressure is used. There is another problem that the opening area is reduced by the above setting even when the dump is combined, and the dump speed when the arm dump is combined is reduced.

In the second example, the arm direction switching valve 23 for controlling the driving of the arm cylinder 40 as the second actuator is provided via the turning priority valve 48 which always constitutes a variable throttle. Since the hydraulic oil is supplied from the hydraulic pressure source 2, the discharge of the hydraulic pressure source 2 due to the pressure loss that occurs when the arm passes through the swing priority valve 48 during the operation of the arm alone, particularly during arm dumping with a high load pressure. There is also a problem that non-negligible energy loss such as a decrease in speed in a horsepower control range due to an increase in pressure occurs. Regarding this point, in the above-described first example, when the arm is dumped, the pressure oil is supplied to the arm cylinder 40 without passing through the throttle, so that the pressure loss accompanying this is suppressed to a small value. .

The present invention has been made in view of the above-mentioned circumstances in the prior art, and has as its object the purpose of having a center bypass passage connected to a hydraulic power source and controlling the driving of a first actuator. Downstream of the directional control valve, a second directional control valve for controlling the driving of the second actuator is disposed, and a throttle characteristic is provided in a parallel line connecting the input port of the second directional control valve and a hydraulic power source. In a hydraulic circuit of a hydraulic working machine provided with an adjustable flow control means, it is possible to reduce a pressure loss generated in the circuit when the second actuator is operated alone, and to reduce a pressure loss generated in the first actuator and the second actuator. It is an object of the present invention to provide a hydraulic circuit of a hydraulic working machine that can obtain a throttle characteristic of a flow control unit according to a driving direction of a second actuator when a combined operation of an actuator is performed.

[0026]

In order to achieve this object, the present invention provides a hydraulic pressure source, a plurality of directional control valves connected to the hydraulic pressure source, and a first of the directional control valves. The first actuator whose driving is controlled by the directional switching valve, and the driving of which is controlled by the second directional switching valve of the plurality of directional switching valves, are controlled in a predetermined first direction and the first direction. A second actuator drivable in any of a second direction which is a reverse direction, wherein at least the first directional control valve connects the hydraulic pressure source to a tank port when neutral, and A center bypass passage for changing the opening area of the passage connected to the tank so as to be smaller in accordance with the amount of operation of the first directional control valve.
The second directional control valve is connected to the first output port and the second output port connected to the second actuator, and the second directional control valve is connected downstream of the center bypass passage of the directional control valve. A first connection port for connecting the first output port to the hydraulic pressure source via a check valve from a downstream side of a center bypass passage of the first directional switching valve when the switching valve is operated in a predetermined one direction;
And a second input port for connecting the second output port to the hydraulic pressure source when the second directional control valve is operated in a predetermined other direction, and a parallel port connected to the hydraulic pressure source. A flow control means provided in the conduit, the throttle characteristic being adjustable; and an adjusting means adjusting the throttle characteristic of the flow control means in accordance with the operation of the first directional control valve. In a hydraulic circuit of a hydraulic working machine capable of supplying a pressure oil of the hydraulic pressure source to a portion located downstream of the check valve via the check valve, the adjusting unit may be configured such that a driving direction of the second actuator is the first direction. And an operation direction detecting means for detecting which one of the directions is the second direction, and a control means for controlling the throttle characteristic of the flow rate control means in accordance with the operation direction detected by the operation direction detecting means. It is.

[0027]

According to the present invention having the above-described structure, the second
When the actuator is operated alone, the pressure oil from the hydraulic source is supplied to the second directional control valve from the downstream of the center bypass passage of the first directional control valve via the check valve without any special throttle means. Therefore, it is possible to prevent the occurrence of pressure loss due to the intervening special throttle means as described above, and to reduce the pressure loss of the entire circuit.

In the combined driving of the first actuator and the second actuator, the first directional control valve is operated, so that the pressure oil flowing through the center bypass passage decreases, and in some cases, the hydraulic oil stops flowing. A part of the pressure oil of the hydraulic pressure source is supplied to the second directional control valve via the parallel pipe and the flow control means. At this time, whether the driving direction of the second actuator is the first direction or the second direction is detected by the operation direction detecting means, and control is performed according to the operation direction detected by the operation direction detecting means. The means controls a throttle characteristic of the flow control means. That is, at the time of such combined driving of the first actuator and the second actuator, it is possible to obtain the throttle characteristic of the flow control means corresponding to the driving direction of the second actuator.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic circuit of a hydraulic working machine according to the present invention will be described below with reference to the drawings. 1 to 3 show a first embodiment of the present invention.
FIG. 1 is a circuit diagram showing a configuration of a first embodiment of the present invention, and FIG. 2 is a diagram showing characteristics of a variable throttle valve provided in the first embodiment shown in FIG. FIG. 3 and FIG.
FIG. 3 is a cross-sectional view showing a structure of a variable throttle valve and an arm direction switching valve portion provided in the first embodiment shown in FIG.

The hydraulic circuit shown in FIG. 1 is drawn corresponding to FIGS. 8 and 10 showing the first and second examples of the prior art described above, and FIG. 3 is a diagram showing the first example of the prior art described above. Are drawn corresponding to FIG.

That is, even in the hydraulic circuit shown in FIG. 1 showing the first embodiment, the first directional control valve connected to the hydraulic source 2 and the discharge line b of the hydraulic source 2, for example, A turning direction switching valve 21, a first actuator whose driving is controlled by the turning direction switching valve 21, that is, a turning motor 50, a second direction switching valve, for example, an arm direction switching valve 23, and an arm A second actuator whose driving is controlled by the use direction switching valve 23, that is, an arm cylinder 40 is provided.

The above-mentioned turning direction switching valve 21 is a center bypass which changes the opening area in accordance with the amount of operation of the turning direction switching valve 21 while connecting the hydraulic pressure source 2 to the tank port 100 when the turning direction is neutral. It has a passage 110, and the arm direction switching valve 23 also has a similar center bypass passage 120.

The arm directional control valve 23 has a first input port 121 and a second input port 122, and a first output port 130b and a second output port 130a. Of these ports, input ports 121 and 12
2 is connected to the hydraulic power source 2 in parallel with the input port 111 of the turning direction switching valve 21 via the parallel conduit z, and is connected to the center bypass passage 110 of the turning direction switching valve 21.
Is connected to the hydraulic pressure source 2 via a downstream portion r of The input port 122 is connected to the arm direction switching valve 23 at the position 23.
a is switched to the arm cylinder 40 by the passage 124a and the meter-in second output port 130a.
When the arm directional control valve 23 is switched to the position 23b, the input port 121 is connected to the conduit t for supplying the pressure oil to the bottom side of the passage 124b.
Is connected to a pipeline s for supplying pressure oil to the rod side of the arm cylinder 40 through the output port 130b.

The downstream portion r of the center bypass passage 110 of the turning direction switching valve 21 and the first input port 121 and the second input port 1 of the arm direction switching valve 23 described above.
A first check valve f that allows the flow of the pressure oil in the direction of the input ports 121 and 122 and prevents the backflow of the pressure oil in the direction of the downstream portion r of the center bypass passage 110 is provided between the first and second valves 22 and 22. It is. Further, an input port 12 is connected to the parallel conduit z.
A second check valve 123 is provided to allow the flow of the pressure oil in the directions 1 and 122 and to prevent the backflow of the pressure oil in the direction of the hydraulic pressure source 2.

The turning pilot valve 403 for operating the turning direction switching valve 21 and the arm direction switching valve 23
, A pilot hydraulic pressure source 401 for supplying pressure oil to these pilot valves 403, 404, a pilot relief valve 402 for defining the magnitude of pilot pressure discharged from the pilot hydraulic pressure source 401, and Pilot line 410 for guiding the pilot pressure generated by pilot valve 404 for switching to position 23a of arm direction switching valve 23
a, a pilot line 410b for guiding the pilot pressure generated by the pilot valve 404 for switching to the position 23b of the arm direction switching valve 23;

The various components described above are the same as those shown in FIGS. 8 to 10 described above.

In the first embodiment, as the flow control means provided in the parallel conduit z connected to the hydraulic pressure source 2 and capable of adjusting the throttle characteristic, it has the largest opening area at the neutral position, From the neutral position to the right position or from the neutral position to the right position.

As the first manipulated variable detecting means for detecting the manipulated variable of the turning direction switching valve 21 which is the first direction switching valve, similarly to the above-described one shown in FIG. 10, the turning pilot valve 403 is used. Is provided with a shuttle valve 405 for taking out a pilot pressure generated by the operation of the pilot valve. A pilot selection valve 500 is provided in connection with the shuttle valve 405. The pilot selection valve 500 is connected to the pipeline 420a,
It is connected to each drive unit of the above-described variable throttle valve 300 via 420b.

Further, one driving portion of the pilot selection valve 500 is connected to a rod of an arm cylinder 40 which is a second actuator from a first input port 121 of an arm direction switching valve 23 which is a second direction switching valve. Operating amount detecting means for detecting the operating amount when the pressure oil is supplied to the side (during the arm dump), that is, the arm pilot valve 4
A detection pipeline 411b for detecting a pilot pressure generated on the pilot pipeline 410b side in accordance with the operation of the valve 04 is connected to the other drive unit of the pilot selection valve 500. The third operation amount detecting means for detecting the operation amount when the pressure oil is supplied from the input port 122 to the bottom side of the arm cylinder 40 (at the time of arm cloud), that is, the pilot pressure generated on the pilot line 410a side A detection pipeline 411a to be detected is connected.

The pilot selection valve 500 detects that the pilot pressure has been generated in the pilot line 410b,
11b, the shuttle valve 405 and the line 42
0b and the shuttle valve 405 is switched to shut off the line 420a.
When the detection pipeline 411a detects that a pilot pressure has been generated in the shuttle valve 405a, the shuttle valve 405 is connected to the pipeline 420a, and the shuttle valve 405 is switched to shut off the pipeline 420b. The position has been set.

The above-described variable throttle valve 300 is, for example, shown in FIG.
The aperture characteristic is set in advance as shown in FIG.
That is, as described above, the neutral direction has the largest opening area, and when the detection pressure 411b detects the pilot pressure at the time of performing the arm dumping operation of contracting the arm cylinder 40, the turning direction switching valve 21 is turned on. Operation amount,
That is, as the pilot pressure transmitted to the conduit 420b increases with an increase in the operation amount of the turning pilot valve 403, the opening area thereof gradually decreases, and the arm that extends the arm cylinder 40 by the detection conduit 411a. When the pilot pressure at the time of performing the cloud operation is detected, as the pilot pressure transmitted to the pipeline 420a increases with an increase in the operation amount of the turning pilot valve 403, the opening area thereof gradually decreases, and The degree of decrease in the opening area at the time of the arm cloud where the pilot pressure rises in the line 420a is determined by the line 42
It is set so as to be larger than the degree of decrease at the time of arm dump when the pilot pressure rises to 0b.

Note that the above-described detection lines 411b, 411b
“a” constitutes an operation direction detecting means for detecting whether the driving direction of the arm cylinder 40 is the first direction, ie, the contracting direction, or the second direction opposite to the first direction, ie, the extending direction. I have.

Also, the above-described pilot selection valve 500
And the shuttle valve 405 constitute control means for controlling the throttle characteristic of the variable throttle valve 300 in accordance with the operation direction detected by the above-described operation direction detection means.

Further, the above-mentioned operation direction detecting means and the above-mentioned control means constitute adjusting means for adjusting the throttle characteristic of the variable throttle valve 300 in accordance with the operation of the turning direction switching valve 21.

FIG. 3 shows an example of the structure of the variable throttle valve 300 and the arm direction switching valve 23. The configuration excluding the variable throttle valve 300 is the same as that of the prior art shown in FIG. For example.

That is, even in the structure shown in FIG. 3, the downstream portion r of the turning direction switching valve 21, the parallel line z, the first check valve f, the second check valve 123, the first check valve 123, Input port 121, second input port 122, passage 124
a, 124b, a first output port 130b, and a second output port 130a are provided in the casing body 200;
In particular, the first check valve f and the second check valve 123 are slidably formed, and the first check valve f is provided downstream of the seat surface of the first check valve f. f, a first check passage 151 is provided therein, and on the downstream side of the seat surface of the second check valve 123, a second check passage 152 built in the second check valve 123 is provided. Is provided. Also, bolt 2
01 and the plate 1 integrally with the casing body 200.
The first check passage 151 and the second check passage 152 described above are provided in the plate 150.
Is formed.

Particularly, in the first embodiment, the above-described variable throttle valve 300 is disposed in the plate 150. In FIG. 3, 420a and 420b are conduits connected to the respective drive units of the variable throttle valve 300 shown in FIG.

The operation of the first embodiment configured as described above is as follows.

(1) Arm independent operation When the arm is operated alone, the turning pilot valve 4
03 is not operated, the pilot pressure is not taken out from the shuttle valve 405, and no pressure is generated in the pipelines 420a and 420b. Therefore, the variable throttle valve 300 is maintained at the neutral position where the maximum opening area is obtained, and the variable throttle valve 300 operates. Therefore, an operation relatively similar to the operation in the first example of the prior art shown in FIGS. 8 and 9 is performed. (A) When the arm direction switching valve 23 is operated to the position 23a side The arm pilot valve 404 shown in FIG. 1 is operated to build a pressure in the pilot pipeline 410a, and the arm direction switching valve 23 is moved to the position 23a. When activated to switch to
The pressure oil of the hydraulic pressure source 2 is diverted through the discharge pipe b, and a part of the pressure oil passes through the center bypass passage 110 and the downstream portion r to open the first check valve f and to the second input port 122. Reach.
The remaining pressure oil resulting from the above-mentioned split flow passes through the parallel conduit z, passes through the variable throttle valve 300, opens the second check valve 123, and reaches the second input port 122. The pressure oil thus joined at the second input port 122 flows through the passage 124
a, the fluid flows into the pot side of the arm cylinder 40 through the conduit t, extends the arm cylinder 40, and cloudes an arm (not shown). The pressure oil on the rod side of the arm cylinder 40 is returned to the tank through the pipe s.

(B) The arm direction switching valve 23 is moved to the position 23
When the arm directional switch valve 23 is operated to switch to the position 23b by operating the arm pilot valve 404 shown in FIG. The oil is diverted through the discharge pipe b, and a part of the pressure oil passes through the center bypass passage 110 and the downstream portion r to open the first check valve f and reach the first input port 121. The remaining pressure oil due to the above-mentioned split flow passes through the parallel conduit z, passes through the variable throttle valve 300, opens the second check valve 123, and reaches the first input port 121. The pressure oil thus joined at the first input port 121 enters the rod side of the arm cylinder 40 via the passage 124b and the pipe s of the arm direction switching valve 23, and contracts the arm cylinder 40, not shown. Dump the arm. Arm cylinder 4
The pressure oil on the bottom side of 0 is returned to the tank through the pipe t.

(2) Combined operation of arm and swing (a) Operate arm pilot valve 404 to switch arm direction switching valve 23 to position 23a, and simultaneously operate swing pilot valve 403 to switch swing direction When the valve 21 is switched to one of the upper and lower switching positions in FIG. 1, the pressure oil of the hydraulic power source 2 passes through the discharge pipe b, and a part of the pressure oil passes through the input port 111 and the turning direction switching valve 21 to the turning motor 50. Supplied. The remaining pressure oil passes through the parallel pipe z, the variable throttle valve 300, the second check valve 123, the second input port 122, the passage 124a of the arm direction switching valve 23, and the pipe t to the bottom of the arm cylinder 40. Supplied to the side.

At this time, the arm pilot valve 40
The pilot pressure in the pilot line 410a generated in accordance with the operation 4 is detected in the detection line 411a, and the pilot selection valve 500 is switched to the left position in FIG. 1 by the pilot pressure detected in the detection line 411a. Thus, the shuttle valve 405 is connected to the pipe 420a, and the shuttle valve 405 is disconnected from the pipe 420b.

Therefore, the pilot pressure generated by the operation of the turning direction switching valve 21 is taken out by the shuttle valve 405, and the pilot selection valve 500 and the pipeline 420 are taken out.
The variable throttle valve 300 is guided to the left-hand drive unit in FIG. 1 via a, and is switched to its left position. At this time, the throttle characteristic of the variable throttle valve 300 is the characteristic shown on the left side of FIG. 2 as described above, and is proportional to the increase in the pilot pressure of the pipeline 420a accompanying the increase in the operation amount of the turning direction switching valve 21. Accordingly, the opening area of the variable throttle valve 300 is sharply reduced, and the pressure in the parallel conduit z can be secured sufficiently high to rotate the turning motor 50 even when the load on the arm (not shown) is low.

As a result, the swing motor 50 rotates at a predetermined speed, and the swing of the swing body (not shown) can be realized, and at the same time, the arm cylinder 4 whose load pressure tends to decrease.
An arm cloud operation of extending 0 can be realized.

(B) Operate the arm pilot valve 404 to switch the arm direction switching valve 23 to the position 23b, and simultaneously operate the turning pilot valve 403 to move the turning direction switching valve 21 up or down in FIG. Is switched to the switching position, the hydraulic oil of the hydraulic power source 2 passes through the discharge pipe b, and a part thereof is supplied to the turning motor 50 through the input port 111 and the turning direction switching valve 21. The remaining pressure oil flows through the parallel pipeline z, the variable throttle valve 300, the second check valve 123, the first
Input port 121, passage 1 of arm direction switching valve 23
24b, it is supplied to the rod side of the arm cylinder 40 via the conduit s.

At this time, the arm pilot valve 40
The pilot pressure of the pilot line 410b generated by the operation of Step 4 is detected by the detection line 411b, and the pilot selection valve 500 is switched to the right position in FIG. 1 by the pilot pressure detected by the detection line 411b. Thus, the shuttle valve 405 is connected to the pipe 420b, and the shuttle valve 405 is disconnected from the pipe 420a.

Accordingly, the pilot pressure generated by the operation of the turning direction switching valve 21 is taken out by the shuttle valve 405, and the pilot selection valve 500 and the pipeline 420
The variable throttle valve 300 is guided to the right driving unit in FIG. 1 via b, and is switched to the right position. At this time, the throttle characteristic of the variable throttle valve 300 is the characteristic shown on the right side of FIG. 2 as described above, and the throttle characteristic of the variable throttle valve 300 increases with an increase in the pilot pressure of the pipe 420b accompanying an increase in the operation amount of the turning direction switching valve 21. Accordingly, the opening area of variable throttle valve 300 decreases relatively slowly. In this case, since the load pressure of the arm cylinder 40 is generally large, even if the opening area of the variable throttle 300 is relatively large, the pressure in the parallel conduit z can be secured sufficiently high to rotate the turning motor 50.

As a result, the swing motor 50 can be moved in the same manner as described above.
The arm rotates at a predetermined speed, so that a turning body (not shown) can be turned, and at the same time, an arm dumping operation of contracting the arm cylinder 40 can be realized.

In the first embodiment configured as described above, in the arm independent operation, the pressure supplied from the hydraulic power source 2 is used both when performing the arm cloud operation and when performing the arm dump operation. Part of the oil can be supplied to the arm cylinder 40 via the first check valve f without passing through a special throttle valve or the like, and the rest of the pressure oil supplied from the hydraulic pressure source 2 can be supplied to the variable throttle valve 300 and the second throttle valve. Is supplied to the arm cylinder 40 through the check valve 123, but at this time, the variable throttle valve 3
00 is in a neutral state and has a maximum opening area, that is, in a state where it does not function as a throttle valve. From these, the pressure loss generated in the circuit can be reduced,
Energy loss can be suppressed.

Further, in the combined operation of the arm and the swing, the throttle amount of the variable throttle valve 300 when the arm cloud is combined and the throttle amount of the variable throttle valve 300 when the arm dump is combined can be made relatively small. That is, the optimal throttle amount of the variable throttle valve 300 can be obtained in accordance with the difference in the driving direction of the arm cylinder 40, and the combined operation of the good arm cloud and the swing, the arm dump and the swing with the reduced speed suppressed, and the like. , Both of which can be realized, and excellent workability can be obtained.

Among the problems in the first example of the prior art shown in FIGS. 8 and 9 described above, a long arm having a longer length is used instead of the arm having a standard length provided up to that point. Regarding the reduction of the supply pressure of the pipeline t due to the arm cloud operation that occurs when the replacement is performed, and the deterioration of the acceleration of a revolving body (not shown) due to the reduction of the supply pressure to the revolving motor 50, the first embodiment described above In the example, the operation amount of the turning direction switching valve 21 may be increased as compared with the case before, so that the variable throttle valve 300 is switched to move rightward in FIG. 2, the characteristic of the opening area moves to the left, and the opening area decreases, whereby the supply pressure to the swing motor 50 increases, and good acceleration of a swing body (not shown) can be obtained.

Among the problems in the first example of the prior art shown in FIGS. 8 and 9 described above, the swing force and the arm speed during the swing pressing excavation operation performed by swinging the swing body together with the arm cloud operation. In the first embodiment described above, it is difficult to obtain a favorable relationship between the two. In the first embodiment, depending on the operation amount of the turning direction switching valve 21, that is, the lever operation amount of the turning pilot valve 403, The variable throttle valve 300 can be adjusted to have an opening area that provides a relatively desirable turning force and arm speed.

Among the problems in the first example of the prior art shown in FIGS. 8 and 9 described above, when the arm dump is performed in the free descent direction in the combined operation of the turning operation and the arm dump operation, Regarding the point that sufficient pressure oil cannot be supplied to the swing motor 50 due to the reduced load pressure of the arm cylinder 40 and acceleration of the swing body cannot be obtained, the operation amount of the swing direction switching valve 21 can be increased. Often, this causes the variable throttle valve 300 to be switched to move to the left in FIG. 1, i.e., the characteristic of its opening area moves to the right in FIG. The supply pressure to 50 increases, and good acceleration of a revolving structure (not shown) is obtained.

FIG. 4 is a circuit diagram showing the configuration of the second embodiment of the present invention. In the second embodiment, a variable throttle valve 300a having a maximum opening area at a neutral position and having a reduced opening area when switched to a right position is used as a flow control means provided in a parallel conduit z. It is provided and connected to a shuttle valve 405 for extracting the pilot pressure generated by the turning pilot valve 403 for operating the turning direction switching valve 21, and outputs the pilot pressure extracted by the shuttle valve 405 as an electric signal. The pressure detector 6 for outputting, as an electric signal, the pilot pressure generated in the pipe 410b at the time of arm dumping, of the pilot pressure generated by the pressure detector 601 and the arm pilot valve 404 that operates the arm direction switching valve 23.
02, and a pressure detector 6 that outputs a pilot pressure generated in a pipe 410a as an electric signal at the time of an arm cloud.
03, a controller 700 to which these pressure detectors 601, 602, and 603 are connected, and a pilot hydraulic pressure source 4
And a solenoid proportional valve 606 that is arranged in a pipeline connecting the drive valve of the variable throttle valve 300a and the controller 700 and changes a pilot pressure applied to the pipeline 420 according to a drive signal output from the controller 700.

The above-described controller 700 includes an input unit 700a for inputting signals output from the pressure detectors 601, 602, and 603, a data unit 700b, and an arithmetic unit 70.
0c, and an output unit 700d that outputs a drive signal to the drive unit of the electromagnetic proportional valve 606.

The data section 700b includes a pressure detector 601 and a pressure detector 602 or a pressure detector 603.
(Operation amount) output from the variable throttle valve 300a
The relationship with the target aperture characteristic (aperture area) is set in advance. For example, instead of the "aperture opening area" on the vertical axis shown in FIG. 2 described above, "target aperture characteristic (aperture area)" is set, and the "pilot pressure of conduit 420a" on the horizontal axis in FIG.
Is set as the “first target value corresponding to the value output from the pressure detector 601 multiplied by the value output from the pressure detector 603”, and the “tube” on the horizontal axis in FIG. Road 420
Instead of the “b pilot pressure”, a “second target value corresponding to the value output from the pressure detector 601 multiplied by the value output from the pressure detector 602” is set.

The above-described arithmetic unit 700c includes the pressure detector 6
01 and when the signal is output from both the pressure detector 603, the first target value stored in the data section 700b is selected, and the output value of the pressure detector 601 and the output value of the pressure detector 603 are selected. To calculate a corresponding value in the first target value, and further to calculate a target aperture characteristic (opening area) corresponding to the calculated value. Also,
When a signal is output from both the pressure detector 601 and the pressure detector 602, the above-mentioned second target value stored in the data section 700b is selected, and the output values of the pressure detector 601 and the pressure detector 602 are selected. Is multiplied to calculate a corresponding value of the second target value, and further, a calculation is performed to obtain a target aperture characteristic (opening area) corresponding to the calculated value.

The output unit 700d described above is
The drive signal corresponding to the calculated value obtained in step c
6 is output to the driving unit.

The other components are the same as those shown in FIG.

The shuttle valve 405 and the pressure detector 6 described above
01 constitutes first operation amount detection means for detecting the operation amount of the turning direction switching valve 21, and includes the above-described pressure detector 60.
2 is a first input port 121 of the arm direction switching valve 23
Constitutes a second operation amount detection means for detecting an operation amount when the pressure oil is supplied from the arm cylinder 40 to the arm cylinder 40. The pressure detector 603 described above is connected to the arm from the second input port 122 of the arm direction switching valve 23 to the arm. The third operation amount detection means for detecting the operation amount when the pressure oil is supplied to the cylinder 40 constitutes the third operation amount detection means. And an operation direction detecting means for detecting the driving direction of the operation direction.

The controller 700 and the electromagnetic proportional valve 606 constitute control means for controlling the operation of the variable throttle valve 300a in accordance with the operating direction detected by the operating direction detecting means, that is, controlling the throttle characteristic. ing.

FIG. 5 is a sectional view showing an example of the structure of the variable throttle valve 300a and the arm direction switching valve 23 provided in the second embodiment shown in FIG. As shown in FIG. 5, the variable throttle valve 300a is provided inside the plate 150 as in the first embodiment. FIG.
Reference numeral 420 denotes a conduit connecting the electromagnetic proportional valve 606 and the drive unit of the variable throttle valve 300a. Other structures are the same as those of the first embodiment.

The operation of the second embodiment thus configured is as follows.

(1) Arm Single Operation When the arm is operated alone, the turning pilot valve 4
03 is not operated, the pilot pressure is not taken out from the shuttle valve 405, and therefore, the pilot pressure is not detected from the pressure detector 601. Thus, the arithmetic unit 700c of the controller 700 calculates the first target value and the second target value. Neither is obtained, and no drive signal is output from the output section 700d to the drive section of the electromagnetic proportional valve 606. For this reason,
The proportional solenoid valve 606 is kept in the neutral position, that is, the opening area is kept at the maximum. This state is substantially the same as the arm independent operation in the first embodiment described above.

Therefore, when the arm direction is switched by switching the arm direction switching valve 23 to the position 23a and the arm dump is performed by switching the arm direction switching valve 23 to the position 23b, the hydraulic power source 2 is used. Pressure oil is diverted through the discharge pipe b, a part of which passes through the center bypass passage 110 and the downstream part r, opens the first check valve f, and is guided to the arm direction switching valve 23, and the remaining part due to the diverted flow Passes through the parallel conduit z, passes through the variable throttle valve 300a, opens the second check valve 123, and sets the arm direction switching valve 2
3 and the combined pressure oil is supplied to the arm cylinder 40
Is led to.

(2) Combined operation of arm and turning (a) Operating the arm pilot valve 404 to switch the arm direction switching valve 23 to the position 23a, and simultaneously operating the turning pilot valve 403 to switch the turning direction When the valve 21 is switched to one of the upper and lower switching positions in FIG. 4, the pressure oil of the hydraulic power source 2 passes through the discharge pipe b, and a part of the pressure oil passes through the input port 111 and the turning direction switching valve 21 to the turning motor 50. Supplied. The remaining pressure oil flows through the parallel conduit z, the variable throttle valve 300a, the second check valve 123, the second input port 122, the passage 124a of the arm direction switching valve 23,
It is supplied to the bottom side of the arm cylinder 40 via the pipe t.

At this time, the operation amount of the turning direction switching valve 21 is detected via the shuttle valve 405 and the pressure detector 601, and the arm direction switching valve 23 is detected via the pressure detector 603.
Is detected. These pressure detectors 601, 6
A signal corresponding to the operation amount detected in 03 is read into the arithmetic unit 700c via the input unit 700a of the controller 700. The arithmetic unit 700c reads out the relationship between the target aperture characteristic (opening area), the first target value, and the second target value stored in the data unit 700b.
The first target value is selected based on the input of the signal from C.03. That is, an operation of multiplying a value output from the pressure detector 601 by a value output from the pressure detector 603 is performed to obtain an operation value corresponding to the first target value. Then, a calculation for obtaining a target aperture characteristic (opening area) corresponding to the calculated value is performed. The driving signal corresponding to the opening area obtained by the arithmetic unit 700c in this manner is supplied to the driving unit 700d.
Is output to the drive unit of the electromagnetic proportional valve 606, and the electromagnetic proportional valve 606 is controlled so that the magnitude of the pilot pressure output from the electromagnetic proportional valve 606 corresponds to the opening area obtained by the calculation unit 700c of the controller 700. Drive. As a result, the pilot pressure output from the pilot hydraulic pressure source 401 is controlled by the electromagnetic proportional valve 606, and the variable throttle valve 300a is driven according to the pilot pressure thus controlled. Therefore, the variable throttle valve 300a is controlled such that the opening area thereof becomes the opening area where the throttle characteristic rapidly changes as illustrated in the left part of FIG. 2 obtained by the calculation unit 700c of the controller 700.

(B) The arm direction switching valve 23 is switched to the position 23b by operating the arm pilot valve 404, and at the same time, the turning pilot valve 403 is operated to move the turning direction switching valve 21 up or down in FIG. Is switched to the switching position, the hydraulic oil of the hydraulic power source 2 passes through the discharge pipe b, and a part thereof is supplied to the turning motor 50 through the input port 111 and the turning direction switching valve 21. The remaining pressure oil passes through the parallel pipe z, the variable throttle valve 300a, the second check valve 123, the second input port 122, the passage 124a of the arm direction switching valve 23, and the pipe t of the arm cylinder 40. Supplied to the side.

At this time, the operation amount of the turning direction switching valve 21 is detected via the shuttle valve 405 and the pressure detector 601, and the arm direction switching valve 23 is detected via the pressure detector 602.
Is detected. These pressure detectors 601, 6
A signal corresponding to the operation amount detected in 02 is read into the arithmetic unit 700c via the input unit 700a of the controller 700. The arithmetic unit 700c reads out the relationship between the target aperture characteristic (opening area), the first target value, and the second target value stored in the data unit 700b.
The second target value is selected based on the input of the signal from F.02. That is, an operation of multiplying a value output from the pressure detector 601 by a value output from the pressure detector 602 is performed to obtain an operation value corresponding to the second target value. Then, a calculation for obtaining a target aperture characteristic (opening area) corresponding to the calculated value is performed. The driving signal corresponding to the opening area obtained by the arithmetic unit 700c in this manner is supplied to the driving unit 700d.
Is output to the drive unit of the electromagnetic proportional valve 606, and the electromagnetic proportional valve 606 is controlled so that the magnitude of the pilot pressure output from the electromagnetic proportional valve 606 corresponds to the opening area obtained by the calculation unit 700c of the controller 700. Drive. As a result, the pilot pressure output from the pilot hydraulic pressure source 401 is controlled by the electromagnetic proportional valve 606, and the variable throttle valve 300a is driven according to the pilot pressure thus controlled. Accordingly, the variable throttle valve 300a is controlled so that its opening area becomes an opening area whose throttle characteristic gradually changes as exemplified in the right part of FIG. 2 obtained by the calculation unit 700c of the controller 700.

In the second embodiment constructed as described above, although the driving direction of the arm cylinder 40 is electrically detected, the same operation and effect as those of the first embodiment are obtained.

FIG. 6 is a circuit diagram showing the configuration of the third embodiment of the present invention. In the third embodiment, the controller 70 selects one of the turning priority and the arm priority.
A selection unit 701 for outputting a signal to the input unit 700a of the controller 700 is provided.
The relationship between the target aperture characteristic (opening area), the first target value, and the second target value in the second embodiment described above is set to 00b. The arithmetic unit 700c of the controller 700
When turning priority is selected by the selection unit 701, a value slightly larger than the first target value and the value corresponding to the second target value obtained by the calculation in the above-described second embodiment is set to a value larger than 1. It is obtained by multiplying by a predetermined coefficient, and the drive signal corresponding to the large value is
00 is output from the output unit 700d to the drive unit of the electromagnetic proportional valve 606, and when the arm priority is selected, it corresponds to the first target value and the second target value obtained by the calculation in the second embodiment described above. Is calculated by multiplying a predetermined coefficient smaller than 1 by a predetermined coefficient, and a drive signal corresponding to the smaller value is output to the output unit 70 of the controller 700.
0d is output to the drive unit of the electromagnetic proportional valve 606.

Other structures are the same as those of the second embodiment.

In the third embodiment constructed as described above, in the combined operation of the turning and the arm, for example, when it is expected to improve the working efficiency by giving priority to the turning operation, the turning means is given priority by the selecting means 701. Selected. This allows
In the controller 700, a value slightly larger than the values corresponding to the first target value and the second target value described above is obtained, and a drive signal corresponding to the slightly larger value is output to the drive unit of the electromagnetic proportional valve 606. As a result, a relatively large pilot pressure is supplied to the line 420 so that the solenoid proportional valve 60
6, the variable throttle valve 300a is largely moved to the right position, and the opening area of the variable throttle valve 300a is slightly large.
And a relatively small opening area corresponding to the second target value and the arm direction switching valve 23 from the parallel line z.
Thus, the flow rate flowing into the arm cylinder 40 via the arm is restricted, the pressure supplied to the swing motor 50 is increased, good acceleration of the swing body is obtained, and work efficiency can be improved.

In the combined operation of the turning and the arm, if it is expected to improve the working efficiency by giving priority to the operation of the arm, the selecting means 701 selects the arm priority. As a result, the controller 700 obtains a value slightly smaller than the values corresponding to the first target value and the second target value, and outputs a drive signal corresponding to the slightly smaller value to the drive unit of the electromagnetic proportional valve 606. Is done. As a result, the proportional solenoid valve 606 is driven so that a relatively small pilot pressure is supplied to the conduit 420, and the variable throttle valve 300a moves to the right position with this. The opening area becomes a relatively large opening area corresponding to the above-mentioned slightly smaller first target value and second target value, the pressure supplied to the turning motor 50 is suppressed, and the opening flows into the arm cylinder 40 from the parallel pipe z. The flow rate of the arm increases, the speed of the arm can be increased, and the working efficiency can be improved.

In the third embodiment, if the selecting means 701 is installed inside the operator's room or the like, any one of them can be selected as appropriate according to the situation at the work site, thereby eliminating the need for complicated adjustment work. Good body characteristics are obtained.

FIG. 7 is a circuit diagram showing the configuration of the fourth embodiment of the present invention. In the fourth embodiment, in addition to the configuration of the third embodiment shown in FIG. 6, a pump discharge pressure detector 702 for detecting the pressure of the hydraulic power source 2 and a boom direction switch for driving a boom cylinder (not shown) are provided. A boom pilot pressure detector 703 for detecting the operation amount of the valve is provided.

In the fourth embodiment, the pressure detector 702
The relationship between the target aperture characteristic (opening area) and the first target value and the second target value in the third embodiment described above is corrected in accordance with the detection signals 703 and 703.

In general, when performing a combined operation of three operations of boom lowering, arm clouding, and turning, the arm cloud,
Although the flow rate supplied to the turn is reduced and the turn acceleration is deteriorated as compared to the case where the combined operation of only the two operations of the turn is performed,
In the fourth embodiment configured as described above, for example, the values corresponding to the first target value and the second target value are set according to a signal output from the boom pilot pressure detector 703,
It can be corrected by multiplying by a predetermined coefficient larger than 1, that is, corrected to be a larger value, so that a large pilot pressure can be generated from the electromagnetic proportional valve 606 to the pipe 420. As a result, the opening area of the variable throttle valve 300a is reduced, and a relatively large flow rate can be supplied to the swing motor 50. Good swivel performance is ensured even in such a combined operation of boom lowering, arm clouding, and swing. can do.

[0089]

As described above, according to the present invention, when the second actuator is operated alone, a part of the pressure oil supplied from the hydraulic pressure source is divided and the first direction switching valve is operated. From the downstream side of the center bypass to the second directional control valve via the check valve, and the remaining pressurized oil of the divided flow is supplied from the parallel line via the flow control means having the maximum opening area in the neutral state and the second opening area. The pressure can be supplied to the directional control valve, whereby the pressure loss in the circuit can be reduced, and there is an effect that the energy loss can be suppressed.

In the combined operation of the first actuator and the second actuator, the control means controls the throttle characteristic of the flow control means according to the driving direction of the second actuator detected by the operation direction detecting means. Therefore, good driving of both the first actuator and the second actuator can be realized, and there is an effect that excellent workability can be obtained as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a first embodiment of a hydraulic circuit of a hydraulic working machine according to the present invention.

FIG. 2 is an explanatory diagram showing characteristics of a variable throttle valve provided in the first embodiment shown in FIG.

FIG. 3 is a sectional view showing an example of the structure of a variable throttle valve and an arm direction switching valve portion provided in the first embodiment shown in FIG. 1;

FIG. 4 is a circuit diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 5 is a sectional view showing an example of a structure of a variable throttle valve and an arm direction switching valve portion provided in a second embodiment shown in FIG. 4;

FIG. 6 is a circuit diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 7 is a circuit diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 8 is a circuit diagram showing a first example of a hydraulic circuit of a conventional hydraulic working machine.

FIG. 9 is a sectional view showing the structure of a throttle and an arm direction switching valve portion provided in the first conventional example shown in FIG.

FIG. 10 is a circuit diagram showing a second conventional example.

[Explanation of symbols]

2 Hydraulic Power Source 21 Swing Direction Switching Valve (First Direction Switching Valve) 23 Arm Direction Switching Valve (Second Direction Switching Valve) 23a Position 23b Position 40 Arm Cylinder (Second Actuator) 50 Swing Motor (First) 100 tank port 110 center bypass passage 111 input port 120 center bypass passage 121 first input port 122 second input port 123 second check valve 124a pipe 124b pipe 130a second output port 130b No. 1 output port 150 Plate member 151 First check passage 152 Second check passage 153 Pipe line 200 Casing body 201 Bolt 300 Variable throttle valve (flow control means) 401 Pilot hydraulic pressure source 402 Pilot relief valve 403 Swing pilot valve 404 Pilot valve 405 shuttle valve (first operation amount detection means) 410a pilot line 410b pilot line 411a detection line (third operation amount detection means) 411b detection line (second operation amount detection means) ) 420 pipeline 420a pipeline 420b pipeline 500 pilot selection valve 601 turning pilot pressure detector (first operation amount detection means) 602 arm dump pressure detector (second operation amount detection means) 603 for arm cloud Pressure detector (third manipulated variable detection means) 606 Electromagnetic proportional pressure reducing valve 700 Control means 700a Input section 700b Data section 700c Calculation section 700d Output section 701 Selection section 702 Pump discharge pressure detector 703 Boom pilot pressure detector s tube Path t line b discharge line r downstream part f first check valve z parallel pipe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-296935 (JP, A) JP-A-2-240403 (JP, A) JP-A-56-115434 (JP, A) 25827 (JP, B2) Jikoh 3-52272 (JP, Y2) (58) Fields surveyed (Int. Cl. ⁷ , DB name) E02F 9/22

Claims (7)

(57) [Claims] 1. A hydraulic pressure source, a plurality of directional control valves connected to the hydraulic pressure source, a first actuator whose driving is controlled by a first directional control valve of the directional control valves, Driving is controlled by a second direction switching valve of the plurality of direction switching valves, and can be driven in either a predetermined first direction or a second direction opposite to the first direction. At least the first directional switching valve connects the hydraulic pressure source to the tank port when in neutral and connects the tank to the tank in accordance with the amount of operation of operating the first directional switching valve. A center bypass passage for changing an opening area of the passage so as to be small; connecting the second directional control valve downstream of a center bypass passage of the first directional change valve with respect to the hydraulic pressure source; 2 direction switching valve A first output port connected to the second actuator, and a second output port;
When the second directional control valve is operated in one predetermined direction, the first
A first input port connecting the first output port to the hydraulic pressure source from a downstream side of the center bypass passage of the directional control valve via a check valve; A second input port for connecting the second output port to the hydraulic pressure source during operation, and a flow control means provided in a parallel conduit connected to the hydraulic pressure source and capable of adjusting a throttle characteristic; Adjusting means for adjusting the throttle characteristic of the flow control means in accordance with the operation of the first directional control valve. The pressure of the hydraulic power source is set at a portion located downstream of the check valve via the flow control means. In a hydraulic circuit of a hydraulic working machine capable of supplying oil, the adjusting means detects an operation direction detecting means for detecting whether a driving direction of the second actuator is the first direction or the second direction. , This operation direction detection hand A hydraulic circuit of a hydraulic working machine in which in accordance with the detected operation direction, characterized in that it comprises a control means for controlling the aperture characteristics of the flow control means. A first operation amount detecting means for detecting an operation amount of the first direction switching valve, wherein the operation direction detecting means is connected to a second input terminal of the second direction switching valve via a second input port. Second operation amount detection means for detecting an operation amount when supplying pressure oil to the actuator; and an operation amount when supplying pressure oil to the second actuator from a second input port of the second direction switching valve. 2. A hydraulic circuit for a hydraulic working machine according to claim 1, further comprising third operation amount detecting means for detecting the operation amount. 3. The control means includes a pilot selection valve for controlling a throttle characteristic of the flow control means in accordance with a signal output from the second operation amount detection means or the third operation amount detection means. Claim 2
The hydraulic circuit of the described hydraulic working machine. 4. A target throttle characteristic of a flow rate control unit according to an operation amount output from a first operation amount detection unit and a second operation amount detection unit or a third operation amount detection unit. And a controller for outputting a drive signal corresponding to the determined target throttle characteristic, and controlling the operation of the flow rate control means in accordance with the drive signal output from the controller. 3. The hydraulic circuit according to claim 2, further comprising: an electromagnetic proportional valve that outputs a signal. 5. The control means comprises: an operation amount output from the first operation amount detection means, the second operation amount detection means or the third operation amount detection means, and a target throttle characteristic of the flow rate control means. A controller having a data portion for setting the relationship in advance, selecting means for selecting the relationship set in the data portion of the controller, and a drive signal output from the controller based on the relationship selected by the selecting device 3. A hydraulic circuit for a hydraulic working machine according to claim 2, further comprising: an electromagnetic proportional valve that outputs a control signal for controlling the operation of the flow control means in response to the control signal. 6. A casing forming an outer shell of the second directional control valve.
A first check valve provided in the center bypass passage is slidably disposed in the sing body, and a second check valve provided in the parallel pipe is slidably disposed in the casing body. A plate member provided integrally with the casing body, a flow control means disposed on the plate member, a first check passage provided downstream of a seat surface of the first check valve, A second check passage is provided downstream of the seat surface of the check valve, and a pipe connecting the first check passage and the second check passage is formed inside the plate member. The hydraulic circuit for a hydraulic working machine according to claim 1. 7. The check valve according to claim 6, wherein the first check passage is formed inside the first check valve, and the second check passage is formed inside the second check valve. Hydraulic circuit of hydraulic working machine.