JPH10299027A - Hydraulic drive unit for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic drive unit wherein hydraulic circuits can be simplified while sufficiently reducing loss of energy. SOLUTION: The hydraulic drive unit is composed of three hydraulic pumps 7, 8 and 9, hydraulic actuators 11-17 including a boom cylinder 11, an arm cylinder 12 and a bucket cylinder 13 supplied with pressure oil discharged from the hydraulic pumps and respectively driving a boom, an arm and a bucket, and twelve directional selector valves 18-26, 29, 30 and 48 for controlling direction and flow rate for pressure oil supplied from the pumps 7-9 to the actuators 11-17. The directional selector valve 48 for boom raising and bucket crowding supplies pressure oil, with switching made to a position 48A for boom raising, to the bottom-side oil chamber 11a of the boom cylinder 11, and supplies pressure oil, with switching made to a position 48B for bucket crowding, to the bottom-side oil chamber 13a of the bucket cylinder 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive for a construction machine, and more particularly to a hydraulic drive for a construction machine suitable for a hydraulic excavator.

[0002]

2. Description of the Related Art FIG. 2 is a hydraulic circuit diagram showing an example of the configuration of a conventional hydraulic drive of this type, and FIG. 3 is a side view showing the entire structure of a hydraulic shovel to which the hydraulic drive is applied.
4 (a) and 4 (b) are enlarged views showing how the bucket of the hydraulic shovel opens and closes. The hydraulic excavator shown in FIG. 3 is of a so-called loader type, and includes a boom 2, an arm 3, and a bucket 4 as front members rotatable in a vertical direction which constitute the articulated front device 1.
And a lower traveling body 5 and an upper swing body 6 as driven members. The boom 2, the arm 3, and the bucket 4 are each rotatable in a vertical direction, and the base end of the boom 2 is supported by a front portion of the upper swing body 6. The lower traveling structure 5 includes a crawler belt 5A on the left and right sides, and the upper revolving structure 6
Has a driver's cab 6A.

[0003] The hydraulic drive device shown in FIG. 2 is provided in the hydraulic excavator having the above-described configuration, and includes four hydraulic pumps 7, 8, 9, and 10, and hydraulic oil discharged from these hydraulic pumps 7 to 10. Seven hydraulic actuators 11 to 17 including supplied boom cylinders 11, arm cylinders 12, and bucket cylinders 13 for driving the boom 2, the arm 3, and the bucket 4, respectively, and the hydraulic pumps 7-1
0 thirteen directional control valves 1 for controlling the direction and flow rate of hydraulic oil supplied to the hydraulic actuators 11 to 17
8 to 30.

[0004] In addition to the boom cylinder 11, the arm cylinder 12, and the bucket cylinder 13, the hydraulic actuators 11 to 17 are provided with a lower traveling body 5 of a hydraulic shovel.
Left and right traveling motors 14 and 15 for driving (see FIG. 3)
A swing motor 16 for rotating the upper swing body 6 (same as above) with respect to the lower traveling body 5, and an opening / closing cylinder 17 for opening and closing the bucket 4 via the link member 51 (see FIGS. 4A and 4B). And

Each of the directional control valves 18 to 30 is a center bypass type directional control valve.
The second valve group 32 and the third valve group 33 are divided into three valve groups. The first valve group 31 includes the boom cylinder 11 of the hydraulic actuators 11 to 17.
A first boom directional switching valve 18 connected only to the bucket cylinder 13; a first bucket directional switching valve 19 connected only to the bucket cylinder 13; a first arm directional switching valve 20 connected only to the arm cylinder 12; The opening / closing direction switching valve 21 is connected only to the cylinder 17. The second valve group 32 includes a right traveling direction switching valve 22 connected only to the right traveling motor 14 among the hydraulic actuators 11 to 17, a second arm direction switching valve 23 connected only to the arm cylinder 12, a boom cylinder A second boom directional control valve 24 connected only to the first cylinder 11 and a second bucket directional control valve 2 connected only to the bucket cylinder 13
5 is comprised. The third valve group 33 includes a left traveling direction switching valve 26 connected to only the left traveling motor 15 among the hydraulic actuators 11 to 17, and a boom cylinder 1.
From the third boom directional switching valve 27 connected only to 1, the third bucket directional switching valve 28 connected only to the bucket cylinder 13, and the third arm directional switching valve 29 connected only to the arm cylinder 12 It is configured. The remaining one direction switching valve 30 is a turning direction switching valve 30 connected to the turning motor 16. Also, the first to first
Of the third arm direction switching valves 20, 23, 29, the second
The third arm direction switching valves 23 and 29 are connected to both the bottom side oil chamber 12a and the rod side oil chamber 12b of the arm cylinder 12, but the first arm direction switching valve 20
Regarding the two, one of the two pipelines extending to the arm cylinder 12 side is connected to the bottom side oil chamber 12a, but the other is closed halfway. Similarly, the first to third
The second boom directional control valve 24 of the boom directional control valves 18, 24, and 27 has one of two pipes extending toward the boom cylinder 11 connected to the bottom-side oil chamber 11 a and the other closed halfway. The third bucket directional switching valve 28 of the first to third bucket directional switching valves 19, 25, and 28 is configured such that one of two pipes extending to the bucket cylinder 13 side has a bottom side oil chamber. 13a and the other is closed halfway. The above three pipes are all closed in consideration of the difference in pressure oil flow required for expansion and contraction due to the difference in cross-sectional area between the bottom oil chamber and the rod oil chamber of the hydraulic cylinder.

The hydraulic pumps 7 to 10 are variable displacement pumps each driven by a common motor (not shown).
A first hydraulic pump 7 that discharges hydraulic oil to the first valve group 31, a second hydraulic pump 8 that discharges hydraulic oil to the second valve group 32, and discharges hydraulic oil to the third valve group 33. It comprises a third hydraulic pump 9 and a fourth hydraulic pump 10 for discharging hydraulic oil to the turning motor 16. At this time, in the first valve group 31, all the direction switching valves, that is, the first boom direction switching valve 18, the first bucket direction switching valve 19, the first arm direction switching valve 20,
The opening and closing direction switching valve 21 is connected to the first hydraulic pump 7 in parallel. In the second valve group 32, the right traveling direction switching valve 22 has priority over the remaining second arm direction switching valve 23, second boom direction switching valve 24, and second bucket direction switching valve 25. The second hydraulic pump 8 is connected to supply the pressure oil from the second hydraulic pump 8 to the right traveling motor 14 (for example, connected in tandem in this figure), and the second arm direction switching valve 23 and the second boom direction switching are performed. The valve 24 and the second bucket direction switching valve 25 are connected in parallel with each other. Third valve group 33
, The left traveling direction switching valve 26 includes the remaining third boom direction switching valve 27, the third bucket direction switching valve 28,
The third boom is connected so as to supply the pressure oil from the third hydraulic pump 9 to the left traveling motor 15 with higher priority than the third arm direction switching valve 29 (for example, tandem in this figure). The direction switching valve 27 for use, the direction switching valve 28 for the third bucket, and the direction switching valve 29 for the third arm are connected in parallel with each other. Hydraulic pumps 7, 8,
Relief valves 38, 39, 40, and 41 that communicate with each other when the pressure of the discharge pipe becomes equal to or higher than a set value are provided in pipes branched from the discharge pipes 9 and 10, respectively.
The maximum discharge pressure of the hydraulic pumps 7, 8, 9, 10 is specified. The discharge pressures of the hydraulic pumps 7 to 10 are guided to regulators 42 to 45 for controlling the displacements of the hydraulic pumps 7 to 10, respectively. Each hydraulic pump 7-10 is controlled so that the input torque of
The displacement is controlled. At this time, the self-discharge pressure of the corresponding pump is input to each regulator, and further, the first to third hydraulic pumps 7 to
The discharge pressure of the fourth hydraulic pump 10 via the regulator 45 of the fourth hydraulic pump 10 is input to the regulators 42 to 44 of the ninth part, which is shown in a partially simplified manner.
And the regulator 4 of the first to third hydraulic pumps 7 to 9
Nos. 2-44 are the fourth to effectively utilize the horsepower of the prime mover.
Known cross-sensing with the regulator 45 of the hydraulic pump 10 is performed, and the tilt angles of the first to third hydraulic pumps 7 to 9 are adjusted based on the discharge pressure of the fourth hydraulic pump 10.

The hydraulic drive device shown in FIG.
As operation means provided for each of the hydraulic actuators 11 to 17 for instructing the operation of the boom 2, the arm 3, the bucket 4, the lower traveling body 5, and the upper swing body 6, which are driven members, Operating lever device 34
And a plurality of operating lever devices including a bucket operating lever device 35 (however, operating lever devices 34, 35).
Are omitted from the drawing). The operation lever devices 34 and 35 are controlled by the pilot pressure to the corresponding directional control valves 18, 24, 27.
, 19, 25, and 28, respectively, which are operated by the operator, to generate operating pressures 34a and 35a, and pilot pressures corresponding to the operation amounts and operation directions of the operation levers 34a and 35a, respectively. And a pair of pressure reducing valves 34b and 35b. At this time, the primary port side of the pressure reducing valves 34b and 35b is connected to a hydraulic pressure source, for example, a pilot pump, though not shown in detail. On the secondary port side, the pressure reducing valve 34b of the boom operation lever device 34 is connected to the corresponding first to third boom direction switching valves 18, 2 via the pilot lines 36a and 36b.
4, 27 drive units 18a and 18b, 24a and 24
b, 27a and 27b, and the pressure reducing valve 35b of the bucket operation lever device 35 drives the corresponding first to third bucket direction switching valves 19, 25 and 28 via pilot lines 37a and 37b. Parts 19a and 19
b, 25a and 25b, 28a and 28b. Thereby, the corresponding directional control valve 18, 24, 2 is operated by the operation signal from the operation lever device 34 or 35.
7 or 19, 25, 28 are switched, and the hydraulic pump 7
9 to control the direction and flow rate of the pressure oil supplied to the corresponding hydraulic cylinder 11 or 13. The other operation lever devices have the same configuration, not particularly shown, and the corresponding directional control valve is switched by an operation signal from the operation lever device, and is supplied from the hydraulic pump to the corresponding hydraulic actuator. The direction and the flow rate of the pressurized oil are controlled.

Next, a hydraulic circuit diagram showing another example of the configuration of this type of hydraulic drive device is shown in FIG. The same members as those in FIGS. 2 to 4 are denoted by the same reference numerals, and description thereof will not be repeated. FIG.
The hydraulic drive shown in FIG. 2 is different from the hydraulic drive shown in FIG. 2 in that the fourth hydraulic pump 10, the regulator 45, the relief valve 4
1, the cross piping between pumps is omitted by omitting the peripheral piping, etc., and the turning direction switching valve 30 is moved to the first valve group. Further, the opening / closing direction switching valve 21 provided in the first valve group is replaced with the opening / closing direction switching valve 21. The structure has been moved to the second valve group. That is, in the first valve group 46, the turning direction switching valve 30 has priority over the remaining first boom direction switching valve 18, first arm direction switching valve 20, and first bucket direction switching valve 19. It is connected so that the pressure oil from the first hydraulic pump 7 is supplied to the turning motor 16 (for example, connected in tandem in this figure), so that independence of turning can be ensured.
The first boom direction switching valve 18, the first arm direction switching valve 20, and the first bucket direction switching valve 19 are connected in parallel with each other. The second valve group 47
, The right traveling direction switching valve 22 includes the remaining second arm direction switching valve 23, second boom direction switching valve 24, second bucket direction switching valve 25, and opening / closing direction switching valve 2.
The second arm direction switching valve 2 is connected so as to supply the pressure oil from the second hydraulic pump 8 to the right traveling motor 14 in preference to the first arm 1 (for example, in this figure, connected in tandem).
3. The second boom direction switching valve 24, the second bucket direction switching valve 25, and the opening / closing direction switching valve 21 are connected in parallel with each other. Other structures are almost the same as those in FIG.

[0009]

However, the above-mentioned conventional structure has the following problems. That is, in the hydraulic drive device shown in FIG. 2, the first to third pumps for sending pressure oil to the hydraulic cylinders 11 to 13 related to the front members 2 to 4 are provided.
In addition to the hydraulic pumps 7 to 9, a fourth hydraulic pump 10 for supplying pressure oil only to the swing motor 16 is provided. This increases the number of pumps, increases the cost, complicates the configuration of the hydraulic circuit, and reduces energy loss. Increase. At this time,
When the hydraulic cylinders 11 to 13 related to the front members 2 to 4 and the turning motor 16 are driven together, the first to fourth
It is necessary to discharge pressure oil from all of the hydraulic pumps,
When only the front members 2 to 4 are operated, only the hydraulic cylinders 11 to 13 are driven, and the pressure oil from the fourth hydraulic pump is not required. In such a case, the above-described cross sensing is performed to minimize the displacement of the fourth hydraulic pump, thereby reducing the horsepower of the prime mover that is lost for driving the fourth hydraulic pump. ing. However, a pipe for performing the cross sensing (a pipe for connecting the regulators, which is simplified by a single broken line in FIG. 2) is required, and this also complicates the configuration of the hydraulic circuit, resulting in energy loss. Increase.

On the other hand, in the hydraulic drive device shown in FIG. 5, the number of pumps is reduced to three, and since no cross sensing is performed, the circuit configuration is simplified, and the energy loss is reduced accordingly. . However, in the second valve group 47, since the five directional switching valves 22, 23, 24, 25, and 21 are arranged in the center bypass line, the pressure loss increases, and the energy loss is insufficiently reduced.

An object of the present invention is to provide a hydraulic drive device for a construction machine capable of simplifying a hydraulic circuit while sufficiently reducing energy loss.

[0012]

[Means for Solving the Problems]

(1) In order to achieve the above object, the present invention is provided for a construction machine provided with a plurality of driven members including a plurality of vertically rotatable front members constituting an articulated front device. A plurality of hydraulic actuators including at least one hydraulic pump, a plurality of hydraulic cylinders supplied with pressure oil discharged from the hydraulic pump, and driving the plurality of front members, and the plurality of hydraulic actuators from the hydraulic pump And a plurality of directional control valves for controlling a direction and a flow rate of the pressure oil supplied to the construction machine, wherein at least one of the plurality of directional control valves is provided.
One is to supply pressure oil to the bottom side of the hydraulic cylinder that drives one of the plurality of front members when switched to the switching position on one side, and to switch to the switching position on the other side when switching to the switching position on the other side. The plurality of front members are connected to supply pressure oil to a bottom side of the hydraulic cylinder that drives another member. In a hydraulic drive having a plurality of hydraulic cylinders for driving a plurality of front members,
Usually, the number of direction switching valves is provided in a number corresponding to the number of types of hydraulic cylinders to be driven. For example, in a hydraulic drive device provided with a boom cylinder, an arm cylinder, and a bucket cylinder as a hydraulic cylinder provided on a construction machine having a boom, an arm, and a bucket as a front member, a large amount of flow is supplied to each cylinder. If necessary, a total of nine direction switching valves for the three types of cylinders, for example, three boom direction switching valves, three arm direction switching valves, and three bucket direction switching valves are provided. By the way, in general, the hydraulic cylinders that drive these front members have a difference in cross-sectional area between the oil chamber on the bottom side and the oil chamber on the rod side. There is a difference. That is, the inflow flow rate of the bottom oil chamber required to extend the hydraulic cylinder is
The rod-side oil chamber inflow flow rate required to contract the hydraulic cylinder is smaller. Therefore, considering the inflow flow rate required for the oil chamber of each hydraulic cylinder, in the above example, three switching position portions connected to the bottom side of each cylinder among the directional switching valves for each cylinder are required. If there are, the number of switching position parts connected to the rod side of each cylinder among the direction switching valves for each cylinder is originally, for example, two. Therefore, in the present invention, at least one of the plurality of directional switching valves is configured to supply the pressure oil to the bottom side of the hydraulic cylinder that drives one of the plurality of front members at the one switching position. In the switching position on the other side, a connection is made so as to supply pressure oil to the bottom side of a hydraulic cylinder that drives another member of the plurality of front members. That is, at least one directional switching valve is connected to the bottom side of two different types of hydraulic cylinders depending on the switching position. As a result, compared to the conventional case where the number of direction switching valves is simply provided in accordance with the number of types of hydraulic cylinders,
The number of directional control valves can be reduced. For example, in the above example, if one directional switching valve is connected to the bottom side of the boom cylinder and the bottom side of the bucket cylinder, the other necessary directional switching valves are the bottom side of the boom cylinder and Two ordinary boom directional switching valves connected to the rod side, two ordinary bucket directional switching valves connected to the bottom and rod sides of the bucket cylinder, and connected to the bottom and rod sides of the arm cylinder The number of directional switching valves for the arm to be used is three, and a total of eight directional switching valves are sufficient. Therefore, the number of directional switching valves can be reduced by one, and the configuration of the hydraulic circuit can be simplified accordingly. it can. Usually, since a certain pressure loss occurs in each directional control valve, the number of directional control valves that can be connected to the discharge side of one hydraulic pump has a certain limit. Can be reduced, and the number of hydraulic pumps can be reduced under the same restrictions as in the conventional structure. At this time, the energy loss due to the pressure loss does not increase unlike the conventional structure in which the number of directional control valves per pump is increased. As described above, the number of direction switching valves can be reduced, and the number of hydraulic pumps can be reduced without increasing energy loss. Therefore, the hydraulic circuit can be simplified while energy loss is sufficiently reduced.

(2) In the above (1), preferably,
The apparatus further includes a plurality of operation means for instructing the operation of the plurality of driven members, and the plurality of operation means includes an operation means for instructing an operation of the one member and an operation of the other member. And at least one directional switching valve, wherein the at least one directional switching valve includes one driving unit to which an operation signal for switching from the one operating means to the one-side switching position is input, and the other operating means And an operation signal for inputting an operation signal for switching to the switching position on the other side.

(3) In the above (2), more preferably, an operation signal for switching to the switching position on the one side from the one operating means and a switching position on the other side from the other operating means are provided. When an operation signal to be switched is simultaneously output, a selection means for guiding any one of the operation signals to the corresponding drive unit in preference to the other operation signal is further provided. Accordingly, even in the case of a composite operation in which an operation signal for switching from one operation unit to a switching position on one side and an operation signal for switching to a switching position on another side from another operation unit are superimposed, at least One directional control valve is switched to the side where the operation signal is prioritized, and the corresponding front member can be operated smoothly. (4) a boom, an arm,
(1) provided in a construction machine provided with a bucket and a bucket
Preferably, the plurality of hydraulic cylinders include a boom cylinder that drives the boom, an arm cylinder that drives the arm, and a bucket cylinder that drives the bucket, wherein the at least one directional switching valve is The boom cylinder, the arm cylinder, and the pressurized oil are supplied to the bottom side of one of the bucket cylinders when switched to the switching position on one side, and the boom cylinder when switched to the switching position on the other side, The arm cylinder and the bucket cylinder are connected to supply pressure oil to the bottom side of another cylinder.

(5) In the above (4), more preferably, the plurality of directional control valves serve as the at least one directional control valve when the directional control valve is switched to the one side switching position. Supply pressure oil to
A different cylinder switching direction switching valve connected to supply pressure oil to the bottom side of the bucket cylinder when the switching position is switched to the other side switching position; and the different cylinder switching direction switching valve. Other directional switching valves other than the first and second boom directional switching valves connected only to the boom cylinder of the hydraulic cylinder, and the first and second directional switching valves connected only to the arm cylinder of the hydraulic cylinder. A second and a third arm direction switching valve, and first and second bucket direction switching valves connected only to the bucket cylinders of the hydraulic cylinder;
The hydraulic pump discharges hydraulic oil to a plurality of direction switching valves including the first boom direction switching valve, the first arm direction switching valve, and the first bucket direction switching valve. A second hydraulic pump for discharging pressure oil to a plurality of direction switching valves including a pump, the second boom direction switching valve, the second arm direction switching valve, and the second bucket direction switching valve; And a third hydraulic pump for discharging hydraulic oil to a plurality of direction switching valves including the direction switching valve for switching different cylinders and the direction switching valve for the third arm.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a hydraulic circuit diagram illustrating a configuration of the hydraulic drive device according to the present embodiment. Members equivalent to those in FIGS. 2 to 5 for describing the conventional structure are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In FIG. 1, the hydraulic drive device of the present embodiment is provided, for example, in a loader type hydraulic shovel shown in FIGS. 3 and 4 similarly to the conventional structure. The opening / closing direction switching valve 21 corresponding to the second valve group 47 is moved to the position of the third bucket direction switching valve 28 of the three valve group 33, and
The boom direction switching valve 24 is also connected to the bottom side oil chamber 11a of the boom cylinder 11 while keeping the same position, and the third
At the position of the third boom direction switching valve 27 of the valve group 33, a boom raising / bucket cloud direction switching valve 48 as a different cylinder switching direction switching valve is provided. That is, only the four directional control valves 22, 23, 24, and 25 are provided in the second valve group 47, of which the right directional control valve 22 is the remaining directional control valve 23 for the second arm, and the second directional control valve 23 is the second directional control valve. The second hydraulic pump 48 has priority over the boom direction switching valve 24 and the second bucket direction switching valve 25.
(For example, connected in tandem in this figure) so as to supply the pressure oil to the right traveling motor 14, the second arm directional switching valve 23, the second boom directional switching valve 24, and the second bucket The direction switching valves 25 are connected in parallel with each other. At this time, similarly to the first boom direction switching valve 18, the second boom direction switching valve 24 is configured such that one of two pipes extending toward the boom cylinder 11 is connected to the bottom side oil chamber 1.
The other is connected to the rod-side oil chamber 11b. The third valve group 49 includes a left traveling direction switching valve 26 and a boom raising / bucket cloud direction switching valve 4.
8. Opening / closing direction switching valve 21, third arm direction switching valve 2
9 are provided, of which the left direction switching valve 26 has priority over the remaining boom raising / bucket cloud direction switching valve 48, opening / closing direction switching valve 21, and third arm direction switching valve 29. Are connected so as to supply the pressure oil of the third hydraulic pump 9 to the left traveling motor 15 (for example, connected in tandem in this figure), the boom raising / bucket cloud direction switching valve 48, the opening / closing direction switching valve 21 , Third
The arm direction switching valves 29 are connected in parallel with each other.

The boom raising / bucket cloud direction switching valve 48 supplies pressure oil to the bottom side oil chamber 11a of the boom cylinder 11 when it is switched to one side, that is, the boom raising side switching position 48A. Is connected to supply pressure oil to the bottom oil chamber 13a of the bucket cylinder 13 when it is switched to the other side, that is, the switching position 48B on the bucket cloud side. In addition, boom raising
The bucket cloud direction switching valve 48 is provided on one side, that is, the boom raising drive unit 48a, to which an operation signal for switching from the boom operation lever device 34 to the boom raising switching position 48A is input via the pilot line 36a.
And a driving unit 48b on the other side, that is, the bucket cloud side, to which an operation signal for switching from the bucket operation lever device 35 to the switching position 48B on the bucket cloud side is input via the pilot line 37a. Switching is performed by inputting these operation signals. Further, a switching valve 50 is provided on the pilot line 37a connected to the driving unit 48b, which can communicate and shut off the pilot line 37a depending on whether the pilot pressure of the pilot line 36a is guided to the driving unit 50A. As a result, the switching valve 50 simultaneously outputs the operation signal for switching to the boom raising side switching position 48A from the boom operation lever device 34 and the operation signal for switching to the bucket cloud side switching position 48B from the bucket operation lever device 35. When the signal is output, the operation signal on the boom raising side is guided to the corresponding drive unit 48a prior to the operation signal on the bucket cloud side.

Other structures are almost the same as those of the hydraulic drive device shown in FIG.

In the above configuration, the boom cylinder 1
1 constitutes a hydraulic cylinder for driving the boom 2 as one member of the plurality of front members, and the bucket cylinder 13 constitutes a hydraulic cylinder for driving the bucket 4 as another member of the plurality of front members. .
The boom operation lever device 34 constitutes one operation means for instructing the operation of one member, and the bucket operation lever device 35 constitutes another operation means for instructing the operation of another member. Further, the switching valve 50 is configured such that when an operation signal for switching to the switching position on one side from one operation means and an operation signal for switching to the switching position on the other side from another operation means are simultaneously output, A selection means is configured to guide one of the operation signals to the corresponding drive unit prior to the other operation signal.

The operation of the boom cylinder 11 and the bucket cylinder 13 in the above configuration and the operation thereof will be described below.
A description will be given in the order of (1) the case of performing the boom independent operation, (2) the case of performing the bucket alone operation, and (3) the case of performing the combined operation of the boom and the bucket. (1) Boom independent operation First, in the case of the boom raising operation, when the operation lever 34a of the boom operation lever device 34 is operated, a pilot pressure as an operation signal is raised on the boom raising side pilot line 36a, and this pilot line 36a is generated. The pilot pressure is guided to the driving portion 18a of the first boom direction switching valve 18, the driving portion 24a of the second boom direction switching valve 24, and the driving portion 48a of the boom raising / bucket cloud direction switching valve 48 which are connected. These directional control valves 18, 24, 48
Are switched to the boom raising switching positions 18A, 24A, 48A, respectively, and the pressure oil of the first to third hydraulic pumps 7 to 9 flows into the bottom oil chamber 11a of the boom cylinder 11 via these three. At this time, the return oil from the rod-side oil chamber 11b is divided into two positions: a switching position 18A of the first boom directional switching valve 18 and a switching position 24A of the second boom directional switching valve 24 connected to the oil chamber 11b. Through the tank. At this time, as described above, since there is a difference in cross-sectional area between the bottom-side oil chamber 11a and the rod-side oil chamber 11b, even with such a pressurized oil flow, a sufficient amount of boom cylinder 11 equivalent to the conventional one can be obtained. Elongation speed can be secured. On the other hand, in the case of the boom lowering operation, the operation lever device 3 for the boom is used.
By operating the operation lever 34a of No. 4, a pilot pressure as an operation signal rises in the pilot line 36b on the boom lowering side, and the first pilot line connected to the pilot line 36b.
The pilot pressure is guided to the driving portion 18b of the boom directional switching valve 18 and the driving portion 24b of the second boom directional switching valve 24, and these directional switching valves 18, 24 are switched to the switching positions 18B, 24B on the boom lower side, respectively. Then, the pressure oil of the first and second hydraulic pumps 7, 8 flows into the rod-side oil chamber 11b of the boom cylinder 11 via these two. At this time, the return oil from the bottom side oil chamber 11a is
Switching position 18B of the first boom directional switching valve 18 and switching position 2 of the second boom directional switching valve 24
4B to the tank via two of them.

(2) Single bucket operation In the case of bucket cloud operation, when the operating lever 35a of the bucket operating lever device 35 is operated, a pilot pressure as an operation signal is raised on the pilot line 37a on the bucket cloud side, and this pilot pressure is applied. Line 37a
1 of the first bucket directional control valve 19 connected to the
9a, the drive unit 25a of the second bucket direction switching valve 25,
The pilot pressure is guided to the driving portion 48b of the boom raising / bucket cloud direction switching valve 48, and these direction switching valves 19, 25, and 48 are switched to the bucket cloud side switching position 1.
9A, 25A, and 48B, respectively.
The pressure oil of the third hydraulic pumps 7 to 9 flows into the bottom oil chamber 13a of the bucket cylinder 13 via these three. At this time, the return oil from the rod-side oil chamber 13b is
It is discharged to the tank via two switching positions 19A of the first bucket direction switching valve 19 and the switching position 25A of the second bucket direction switching valve 25 which are connected to 3b. At this time, similarly to (1), since there is a difference in cross-sectional area between the bottom-side oil chamber 13a and the rod-side oil chamber 13b, even in such a pressurized oil flow, a sufficient amount of the bucket cylinder 13 equivalent to the conventional one is sufficient. High elongation speed can be secured. On the other hand, in the case of the bucket dump operation, when the operation lever 35a of the bucket operation lever device 35 is operated, a pilot pressure as an operation signal is generated in the pilot line 37b on the bucket dump side, and the first bucket connected to the pilot line 37b is operated. The pilot pressure is guided to the driving portion 19b of the direction switching valve 19 for use and the driving portion 25b of the direction switching valve 25 for the second bucket, and these direction switching valves 19 and 25 are switched to the switching positions 19B and 25B on the bucket dump side, respectively. , First and second
The pressure oil of the hydraulic pumps 7, 8 flows into the rod-side oil chamber 13b of the bucket cylinder 13 via these two. At this time, the return oil from the bottom side oil chamber 13a is
Are discharged to the tank via two switching positions 19B of the first bucket direction switching valve 19 and the switching position 25B of the second bucket direction switching valve 25 which are connected to the tank.

(3) Combined operation of boom and bucket First, in the case of the boom raising / bucket cloud operation, when the operation lever 34a of the boom operation lever device 34 and the operation lever 35a of the bucket operation lever device 35 are operated, the boom A pilot pressure as an operation signal is raised in each of the up pilot line 36a and the bucket cloud side pilot line 37a. However, at this time, the pilot pressure in the pilot line 36a is guided to the drive unit 50A of the switching valve 50, so that the switching valve 50
Is switched to a position where the pilot line 37a is cut off. As a result, the pilot pressure generated by the bucket operating lever device 35 is not transmitted to the pilot line 37a downstream of the switching valve 50. Due to the function of the switching valve 50, the pilot line 3
6a, a driving portion 18a of the first boom directional switching valve 18, a driving portion 24a of the second boom directional switching valve 24,
The pilot pressure from the boom operation lever device 34 is guided to the drive portion 48a of the boom raising / bucket cloud direction switching valve 48, and these direction switching valves 18, 24, 48 are provided.
Are switched to the switching positions 18A, 24A, 48A on the boom raising side, respectively. At the same time, the pilot pressure from the bucket operating lever device 35 is guided to the driving portion 19a of the first bucket direction switching valve 19 and the driving portion 25a of the second bucket direction switching valve 25 connected to the pilot line 37a. Thus, these direction switching valves 19 and 25 are switched to the switching positions 19A and 25A on the bucket cloud side, respectively. At this time, regarding the pressure oil from the first hydraulic pump 7, the first boom directional switching valve 18 and the first bucket directional switching valve 19 are connected in parallel to each other as described above. Therefore, this pressure oil
The switching position 18A of the first boom directional switching valve 18 and the first
Via the switching position 19A of the bucket direction switching valve 19,
The oil flows into both the bottom oil chamber 11a of the boom cylinder 11 and the bottom oil chamber 13a of the bucket cylinder 13.
However, in this boom raising / bucket cloud combined operation, since the load of the boom cylinder 11 is larger than the load of the bucket cylinder 13, the pressure oil mainly flows to the bottom oil chamber 13a of the bucket cylinder 13, that is, the bucket cloud operating side. The same applies to the pressure oil from the second hydraulic pump 8. Then, as described above, the pressure oil from the third hydraulic pump 9 is entirely supplied to the bottom-side oil chamber 11a of the boom cylinder 11 via the switching position 48A on the boom raising side of the boom raising / bucket cloud direction switching valve 48. Flows into. Thus, the boom cylinder 1
Since the pressurized oil is supplied to both the bottom oil chamber 11a and the bottom oil chamber 13a of the bucket cylinder 13, the combined operation of raising the boom and bucket cloud can be reliably performed.

In the case of a boom raising / bucket dump operation, the operation lever 34 of the boom operation lever device 34 is used.
a and the operating lever 35 of the bucket operating lever device 35
When a is operated, the pilot line 36 on the boom raising side is operated.
Pilot pressure rises in each of a and the pilot line 37b on the bucket dump side. The driving section 18a of the first boom directional control valve 18 connected to the pilot line 36a and the driving section 24 of the second boom directional switching valve 24 are connected.
a, boom raising / bucket cloud direction switching valve 4
The pilot pressure from the boom operation lever device 34 is guided to the drive portion 48a of the directional control valve 8 so that the direction switching valves 18, 24,
48 is a switching position 18A, 24A, 48A on the boom raising side.
Respectively. At the same time, the first bucket directional switching valve 1 connected to the pilot line 37b
The pilot pressure from the bucket operating lever device 35 is guided to the driving unit 19b of the ninth and the driving unit 25b of the second bucket directional switching valve 25, and these directional switching valves 19, 25 are switched to the bucket dump side switching positions 19B, 25B. Respectively. Here, as described above, the first boom directional switching valve 18 and the first bucket directional switching valve 19 are connected in parallel to each other, but in this combined operation of boom raising and bucket dumping, the load of the boom cylinder 11 is larger than that of the bucket. Since the load is larger than the load of the cylinder 13, the first
The pressure oil from the second hydraulic pumps 7 and 8 mainly flows to the rod-side oil chamber 13b of the bucket cylinder 13, that is, the bucket dump operation side. Then, all the pressure oil from the third hydraulic pump 9 flows into the bottom-side oil chamber 11a of the boom cylinder 11 through the boom-raising-side switching position 48A of the boom raising / bucket cloud direction switching valve 48. Thus, the bottom-side oil chamber 11a of the boom cylinder 11 and the rod-side oil chamber 13 of the bucket cylinder 13
Since the pressure oil is supplied to both b, the combined operation of boom raising and bucket dump can be reliably performed.

Further, in the case of the boom lowering / bucket cloud operation, when the operating lever 34a of the boom operating lever device 34 and the operating lever 35a of the bucket operating lever device 35 are operated, the pilot line 36b on the boom lowering side and the bucket cloud are operated. Side pilot line 37
Pilot pressure is set up in each of a. The first boom directional control valve 1 connected to the pilot line 36b
The pilot pressure from the boom operation lever device 34 is guided to the drive unit 18b of the second boom 8 and the drive unit 24b of the second boom directional control valve 24, and these directional control valves 18, 24 are switched to the boom lower side switching positions 18B, 24B. Respectively. At the same time, the driving unit 19a of the first bucket direction switching valve 19 connected to the pilot line 37a, the driving unit 25a of the second bucket direction switching valve 25, and the driving of the boom raising / bucket cloud direction switching valve 48. Part 4
The pilot pressure from the bucket operation lever device 35 is guided to 8b, and these direction switching valves 19, 25, 48 are switched to the switching positions 19A, 25A, 48B on the bucket cloud side, respectively. Here, as described above, the first boom directional switching valve 18 and the first bucket directional switching valve 19
Are connected in parallel with each other, but in this boom lowering / bucket cloud combined operation, since the load on the boom cylinder 11 is smaller than the load on the bucket cylinder 13, the hydraulic oil from the first and second hydraulic pumps 7, 8 The pressure oil mainly flows to the rod-side oil chamber 11b of the boom cylinder 11, that is, the boom lowering operation side. The pressure oil from the third hydraulic pump 9 is supplied to the switching position 4 on the bucket cloud side of the boom raising / bucket cloud direction switching valve 48.
All flow into the bottom side oil chamber 13a of the bucket cylinder 13 via 8B. Thus, the boom cylinder 11
Since the pressure oil is supplied to both the rod-side oil chamber 11b and the bottom-side oil chamber 13a of the bucket cylinder 13, the boom lowering / bucket cloud combined operation can be reliably performed.

In the case of the boom lowering / bucket dumping operation, the operation lever 34 of the boom operation lever device 34 is used.
a and the operating lever 35 of the bucket operating lever device 35
When a is operated, the pilot line 36 on the boom lower side is operated.
A pilot pressure as an operation signal is generated in each of the b and the bucket dump side pilot line 37b, and the first and second boom direction switching valves 18 and 24 are switched to the boom lowering side switching positions 18B and 24B, respectively. The first and second bucket direction switching valves 19 and 25 are switched to the switching positions 19B and 25B on the bucket dump side, respectively. As described above, since the first boom directional switching valve 18 and the first bucket directional switching valve 19 are connected in parallel with each other, the hydraulic oil from the first and second hydraulic pumps 7, 8 is supplied to the boom cylinder. 11, the rod-side oil chamber 11b of the bucket cylinder 13
And flows to both. As a result, the combined operation of boom lowering and bucket dumping can be reliably performed.

According to the hydraulic drive system of the present embodiment configured as described above, the following effects can be obtained. That is, as described with reference to FIGS. 2 and 5, in a hydraulic drive device having a plurality of hydraulic cylinders for driving a plurality of front members, normally, the direction switching valve is provided with the number of types of hydraulic cylinders to be driven. Are provided according to the number. That is, in the hydraulic drive devices of FIGS. 2 and 5, the first to third boom direction switching valves 18, 24, 27, and the first to third boom direction switching valves are used as direction switching valves for guiding hydraulic oil to the boom cylinder, arm cylinder, and bucket cylinder. A total of nine direction switching valves 20, 23, 29 for the third arm and direction switching valves 19, 25, 28 for the first to third buckets were provided. However, considering the pressure oil flow required for the expansion and contraction of each hydraulic cylinder while considering the sectional area difference between the bottom oil chamber and the rod oil chamber of the hydraulic cylinder described above, the direction switching valve for each cylinder is considered. If three switching positions connected to the bottom side of each cylinder are required, two switching positions connected to the rod side of each cylinder in each cylinder direction switching valve are originally sufficient, for example, two. Should be. From this viewpoint, according to the present embodiment, one boom raising / bucket cloud direction switching valve 48 is provided, and the pressure oil is supplied to the bottom oil chamber 11a of the boom cylinder 11 at the switching position 48A on the boom raising side. At the switching position 48B on the bucket cloud side, so as to supply pressure oil to the bottom side oil chamber 13a of the bucket cylinder 13. As a result, the directional switching valve that guides the pressure oil to the boom cylinder, the arm cylinder, and the bucket cylinder is different from the directional switching valve 48 in addition to the bottom oil chamber 1 of the boom cylinder 11.
The first and second boom directional switching valves 18 and 24 connected to the first and second rod-side oil chambers 11a and 11b, the bottom-side oil chamber 13a and the rod-side oil chamber 13b of the bucket cylinder 13, respectively.
First and second bucket directional switching valves 19 and 25 connected to the bottom oil chamber 12 of the arm cylinder 12.
a and the normal first to third arm direction switching valves 20, 23, 29 connected to the rod side oil chamber 12b, and the total number of the direction switching valves is eight. Therefore, the number of directional control valves can be reduced by one in comparison with the conventional structure of FIGS. Therefore, the configuration of the hydraulic circuit can be simplified accordingly. Usually, since a certain pressure loss occurs in each directional control valve, the number of directional control valves that can be connected to the discharge side of one hydraulic pump is limited, but as described above, the number of directional control valves is reduced. By doing so, the number of hydraulic pumps can be reduced. For example, in the conventional structure shown in FIG. 2, the limit of the number of the directional control valves that can be connected to the discharge side of the hydraulic pump is configured as four, so that a total of thirteen directional control valves are arranged. Four hydraulic pumps 7 to 10 including the fourth hydraulic pump 10 dedicated to turning have been required. On the other hand, in the present embodiment, the total number of the directional control valves can be set to 12, so that three hydraulic pumps 7 to 9 are sufficient and the number of hydraulic pumps is reduced by one under the same restrictions. can do. Although the number of hydraulic pumps is the same as the conventional structure of FIG. 5, the number of directional switching valves connected to the discharge side of one hydraulic pump is four. Energy loss due to pressure loss does not increase unlike the structure of FIG. 5 in which two directional control valves are arranged. As described above, the number of directional control valves can be reduced, and the number of hydraulic pumps can be reduced without increasing energy loss due to pressure loss. Therefore, it is possible to simplify the hydraulic circuit while sufficiently reducing energy loss.

In the above embodiment, the boom raising / bucket cloud direction switching valve 48 is provided as the different cylinder switching direction switching valve, but the invention is not limited to this. That is, the configuration related to the bucket cloud operation may be modified to the configuration related to the arm cloud operation, and the boom raising / arm cloud direction switching valve may be used. Further, a direction switching valve for bucket cloud / arm cloud may be used. In these cases, substantially the same effect is obtained. Further, the number of such directional switching valves for switching different cylinders is not limited to one. For example, when a larger flow rate supply is required, a large number of directional switching valves for booms, arms, and buckets are used. If it is necessary to use a valve, two or more boom raising / bucket cloud direction switching valves are provided, or one boom raising / bucket cloud direction switching valve and one boom raising / arm cloud are provided. And a direction switching valve for use. In the above embodiment,
The switching valve 50 as the selection means gives priority to the pilot pressure in the pilot line 36a, which is the boom raising operation signal, but is not limited to this. That is, a configuration may be adopted in which the pilot pressure in the pilot line 37a, which is the bucket cloud operation signal, is prioritized. However, in this case, it is necessary to devise the arrangement order and connection of the respective directional control valves in the first valve group 46 and the second valve group 47 so that the combined operation of the boom raising and the bucket cloud can be reliably performed. . Further, in the above embodiment, the case where the present invention is applied to the loader type excavator as shown in FIGS. 3 and 4 has been described. However, the present invention is not limited to this, and may be applied to a backhoe type excavator. it can. However, in this case, the opening / closing direction switching valve 2 of FIG.
1 becomes unnecessary. However, in general, in this type of hydraulic drive device, the same hydraulic circuit configuration is commonly used for a backhoe type excavator and a loader type excavator. The position where the direction switching valve 21 is located may be used as a spare spool, and may be used as an attachment direction switching valve, for example, when attaching an attachment to a bucket. Further, in the above-described embodiment, the case where the present invention is applied to a hydraulic shovel as an example of a construction machine has been described. However, the present invention is not limited to this and can be applied to other construction machines such as a crane.

[0028]

According to the present invention, the number of directional control valves can be reduced, and the number of hydraulic pumps can be reduced without increasing energy loss. Therefore, the hydraulic circuit is simplified while energy loss is sufficiently reduced. can do.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram illustrating a configuration of a hydraulic drive device according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram illustrating an example of a configuration of a conventional hydraulic drive device.

FIG. 3 is a side view illustrating the entire structure of the hydraulic excavator.

FIG. 4 is an enlarged view showing a state where a bucket of the hydraulic shovel shown in FIG. 3 opens and closes.

FIG. 5 is a hydraulic circuit diagram illustrating another example of the configuration of the conventional hydraulic drive device.

[Explanation of symbols]

Reference Signs List 1 front member 2 boom (one member, driven member) 3 arm (driven member) 4 bucket (other member, driven member) 5 lower traveling body (driven member) 6 upper revolving body (driven member) 7 1st hydraulic pump 8 2nd hydraulic pump 9 3rd hydraulic pump 10 4th hydraulic pump 11 boom cylinder (hydraulic actuator) 11a bottom side oil chamber 11b rod side oil chamber 12 arm cylinder (hydraulic actuator) 13 bucket cylinder (hydraulic actuator) 13a Bottom side oil chamber 13b Rod side oil chamber 14 Right traveling cylinder (hydraulic actuator) 15 Left traveling cylinder (hydraulic actuator) 16 Swing motor (hydraulic actuator) 17 Opening / closing cylinder (hydraulic actuator) 18 First boom direction switching valve 19 Direction switching valve for first bucket 20 First arc Direction switching valve 21 opening / closing direction switching valve 22 right traveling direction switching valve 23 second arm direction switching valve 24 second boom direction switching valve 25 second bucket direction switching valve 26 left traveling direction switching valve 29 3 arm direction switching valve 30 turning direction switching valve 34 boom operation lever device (one operation means) 35 bucket operation lever device (other operation means) 48 boom raising / bucket cloud direction switching valve (different cylinder switching) 48A Boom raising side switching position (one side switching position) 48a Boom raising side driving part (one driving part) 48B Bucket cloud side switching position (the other side switching position) Position) 48b bucket cloud side drive unit (other drive unit) 50 switching valve (selection means)

Claims (5)

[Claims] 1. A construction machine comprising a plurality of driven members including a plurality of vertically rotatable front members constituting an articulated front device, at least one hydraulic pump, A plurality of hydraulic actuators including a plurality of hydraulic cylinders supplied with hydraulic oil discharged from a pump and driving the plurality of front members, and directions and flow rates of the hydraulic oil supplied from the hydraulic pump to the hydraulic actuators; And a plurality of directional control valves for controlling a hydraulic pressure control device for a construction machine, wherein at least one of the plurality of directional control valves is configured to switch one of the plurality of front members when switched to a switching position on one side. Supplying hydraulic oil to the bottom side of the hydraulic cylinder that drives the other member, and switching to the switching position on the other side, the other part of the plurality of front members A hydraulic drive device for a construction machine, wherein the hydraulic drive device is connected to supply hydraulic oil to a bottom side of the hydraulic cylinder that drives a material. 2. The hydraulic drive system for a construction machine according to claim 1, further comprising a plurality of operation means for instructing the operation of the plurality of driven members, and wherein the plurality of operation means are the one. A first operating means for instructing the operation of the member and another operating means for instructing the operation of the other member, wherein the at least one directional switching valve is a switching position on the one side from the one operating means; A driving unit for inputting an operation signal for switching to the other side and another driving unit for inputting an operation signal for switching to the switching position on the other side from the other operation means. Hydraulic drive of the machine. 3. The hydraulic drive device for a construction machine according to claim 2, wherein an operation signal for switching to the switching position on the one side from the one operating means and a switching on the other side from the other operating means. When the operation signal for switching to the position is output simultaneously, there is further provided a selection means for leading one of the operation signals to the corresponding drive unit in preference to the other operation signal, and further comprising a hydraulic device for the construction machine. Drive. 4. A hydraulic drive system for a construction machine according to claim 1, wherein said plurality of hydraulic cylinders drive said boom. A boom cylinder, an arm cylinder that drives the arm, and a bucket cylinder that drives the bucket, wherein the at least one directional switching valve is switched to the one side switching position, and the boom cylinder, the arm cylinder, And pressurized oil is supplied to the bottom side of one of the bucket cylinders, and when switched to the switching position on the other side, the pressurized oil is supplied to the bottom side of the other cylinder among the boom cylinder, the arm cylinder, and the bucket cylinder. A hydraulic drive device for a construction machine, wherein the hydraulic drive device is connected to supply a hydraulic drive. 5. The hydraulic drive device for a construction machine according to claim 4, wherein the plurality of directional control valves are switched to the one side switching position as the at least one directional control valve. A different cylinder switching direction switching valve connected to supply pressure oil to the bottom side and to supply pressure oil to the bottom side of the bucket cylinder when switched to the switching position on the other side; A first and a second boom directional switching valve connected only to the boom cylinder of the hydraulic cylinder, and an arm cylinder of the hydraulic cylinder as other directional switching valves other than the different cylinder switching directional switching valve. First, second, and third arm direction switching valves connected only to the first and second arms, and first and second buckets connected only to the bucket cylinders of the hydraulic cylinders. Contains a preparative directional control valve,
The hydraulic pump discharges hydraulic oil to a plurality of direction switching valves including the first boom direction switching valve, the first arm direction switching valve, and the first bucket direction switching valve. A second hydraulic pump for discharging pressure oil to a plurality of direction switching valves including a pump, the second boom direction switching valve, the second arm direction switching valve, and the second bucket direction switching valve; And a third hydraulic pump for discharging hydraulic oil to a plurality of direction switching valves including the direction switching valve for switching different cylinders and the direction switching valve for the third arm. Hydraulic drive.