JPH09217390A - Hydraulic driving device by load sensing control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely supply pressure oil also to an actuator group belonging to the hydraulic pump on the combination supplying side when the discharge flow rate of one hydraulic pump is supplied in combination with the discharge flow rate of the other hydraulic pump. SOLUTION: A combining circuit 100 formed of a combining-branching selector valve 14 capable of being switched to a branching position for interrupting both discharge circuits 11, 12 of hydraulic pumps 1, 6 and interrupting both load sensing circuits 27, 28, a first combining position for allowing both the discharge circuits to communicate each other through a throttle 50 and interrupting both the load sensing circuits, and a second combining position keeping the communication of both the discharge circuits as they are and also allowing both the load sensing circuits to communicate each other is provided between the discharge circuits 11, 12 of the hydraulic pumps 1, 6 and between the load sensing circuits 27 and 28. The circuit is switched by a combining- branching switching control circuit 200 comprising load sensing differential pressure detecting valves 63, 64, maximum tilting detecting valves 61, 62, and a circuit pressure comparing and detecting valve 60.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive system by load sensing control, and in particular, discharge circuits of two hydraulic pumps are connected by a confluence circuit so that pressure oil can be supplied to a plurality of hydraulic actuators by confluence of two pumps. Hydraulic drive device based on simple load sensing control.

[0002]

2. Description of the Related Art Various conventional techniques for combining / splitting two hydraulic pumps in a hydraulic drive system by load sensing control have been proposed, one of which is disclosed in JP-A-3-84204. There is. FIG.
Reference numeral 2 denotes the conventional technique, which is provided between a variable displacement hydraulic pump 1 driven by a power source such as an engine and actuator groups 2, 3 driven by pressure oil discharged from the hydraulic pump 1. , Directional switching valve groups 4 and 5 for controlling the flow rate of the pressure oil sent from the hydraulic pump 1 to the actuator groups 2 and 3 and switching the feeding direction of the pressure oil are provided. Hydraulic pump 6
Between the actuator groups 7 and 8 which are driven by the pressure oil discharged by the directional control valve group for controlling the flow rate of the pressure oil sent from the hydraulic pump 6 to the actuator groups 7 and 8 and for switching the sending direction of the pressure oil. 9 and 10 are provided.

The discharge circuit 11 of the hydraulic pump 1 and the discharge circuit 12 of the hydraulic pump 6 are connected via a merging / dividing flow switching valve 14. The merging / dividing switching valve 14 supplies the discharge circuit 11 and the load sensing circuit 27 with the load sensing differential pressure ΔP1 between the discharge pressure PS1 of the hydraulic pump 1 and the maximum load pressure PLm1 of the actuator group on the hydraulic pump 1 side on one side thereof, respectively. Load sensing differential pressure Δ between the discharge pressure PS2 of the hydraulic pump 6 and the maximum load pressure PLm2 of the actuator group on the hydraulic pump 6 side with respect to the opposite side.
P2 is guided through the discharge circuit 12 and the load sensing circuit 28, respectively. The load sensing circuit 27 and the load sensing circuit 28 are connected via the shuttle valves 57 and 58 and the merging / diversion switching valve 14.

Here, for example, the discharge flow rate is insufficient with respect to the required flow rate of the directional control valve groups 4 and 5 to which the hydraulic pump 1 corresponds,
When the required flow rate cannot be supplied, the load sensing differential pressure ΔP1 decreases, and the merging / shunting switching valve 14 moves to the position A, that is, from the discharge circuit 12 of the hydraulic pump 6 to the discharge circuit 11 of the hydraulic pump 1. It is switched to a position where oil can be supplied. In this state, the load sensing circuits 27 and 28 are in communication with each other via shuttle valves 57 and 58.

Therefore, in the above-mentioned state, the pressure oil is replenished from the hydraulic pump 6 side to the hydraulic pump 1 side by P
When Lm1 <PLm2, the maximum load pressure P of each
The load sensing control of the hydraulic pumps 1 and 6 is separately performed by Lm1 and PLm2, and when PLm1> PLm2, the maximum load pressure PLm2 on the hydraulic pump 6 side is increased to the maximum load pressure PLm1 on the hydraulic pump 1 side. Then, load sensing control is performed on the hydraulic pumps 1 and 6 by the same maximum load pressure PLm1.

Numerals 20 and 24 are LS control valves, 43 to 4
6 is a pressure compensation valve.

[0007]

However, the above-mentioned conventional merging / splitting method has the following problems.

When the hydraulic pump 1 is in a state of being unable to supply the required flow rate because the discharge flow rate is insufficient with respect to the required flow rate of the direction switching valve group on the hydraulic pump 1 side, the supply flow rate is the combined / diversion switching valve 14 Is switched to the position A, and supplemented by supplying pressure oil from the discharge circuit 12 of the hydraulic pump 6 to the discharge circuit 11 of the hydraulic pump 1. At this time, the maximum load pressure PLm1 of the actuator groups 2 and 3 on the hydraulic pump 1 side and the maximum load pressure PLm1 of the actuator groups 7 and 8 on the hydraulic pump 6 side.
When 2 is PLm1 <PLm2, the load sensing control of the hydraulic pumps 1 and 6 is separately performed by the respective maximum load pressures PLm1 and PLm2. Therefore, the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1, and the discharge flow rate of the hydraulic pump 6 is entirely replenished to the hydraulic pump 1 side due to this pressure difference. Therefore, the pressure oil cannot be supplied to the actuator group on the hydraulic pump 6 side, which causes a phenomenon that an appropriate composite operation cannot be performed. In addition, the combined / diversion switching valve 1
No. 4 switches to the merging position due to the pressure difference between the load sensing differential pressures ΔP1 and ΔP2, so even when both circuits are in the saturation state, the load sensing differential pressure ΔP1
Depending on the pressure difference between ΔP2 and ΔP2, a confluent state may be considered. As a result, in this case as well, a phenomenon occurs in which an appropriate composite operation cannot be performed.

An object of the present invention is to reliably supply pressure oil to an actuator group belonging to a hydraulic pump on the combined supply side when the discharge flow rate of one hydraulic pump is combined with the discharge flow rate of another hydraulic pump and supplied. It is to provide a hydraulic drive device by load sensing control that can be performed.

[0010]

[Means for Solving the Problems]

(1) In order to solve the problems of the above object, the present invention relates to first and second variable displacement hydraulic pumps, and first and second hydraulic pumps driven by the pressure oil discharged from the first and second hydraulic pumps, respectively. A first and a second hydraulic actuator group, and the first
And first and second directional control valve groups for controlling the flow of pressure oil supplied from the second hydraulic pump to the first and second hydraulic actuator groups, and the maximum load pressure of the first hydraulic actuator group. Of the first actuator group detected by the first load sensing circuit, the second load sensing circuit that detects the maximum load pressure of the second hydraulic actuator group, and the first load sensing circuit that detects the maximum load pressure of the second hydraulic actuator group. First discharge amount control means for controlling the discharge amount of the first hydraulic pump so that the pump discharge pressure is higher than the maximum load pressure, and a second hydraulic actuator group detected by the second load sensing circuit. Load sensing control including second discharge amount control means for controlling the discharge amount of the second hydraulic pump so that the pump discharge pressure is higher than the maximum load pressure of In the hydraulic drive system that, said first
Is provided between the discharge circuit of the hydraulic pump and the discharge circuit of the second hydraulic pump, and between the first load sensing circuit and the second load sensing circuit, and both discharge circuits are cut off and both A first merging position that disconnects the load sensing circuit and a first merging position that connects both discharge circuits through a throttle and that blocks both load sensing circuits, and a first merging position that connects both discharge circuits and connects both load sensing circuits. A merging circuit capable of switching to a merging position of 2;
And when one of the second hydraulic pumps cannot supply the required flow rate of the corresponding actuator group and the discharge pressure of the other hydraulic pump is higher than the discharge pressure of the one hydraulic pump. Is switching the merging circuit to the first merging position, the one hydraulic pump is also in a state where it cannot supply the required flow rate, and the discharge pressure of the one hydraulic pump is the discharge pressure of the other hydraulic pump. And a merging / branching switching control means for switching the merging circuit to the second merging position when the temperature is higher than the above.

In the present invention configured as described above, the merging / diversion switching control means is in a state where one of the first and second hydraulic pumps cannot supply the required flow rate of the corresponding actuator group. When the discharge pressure of the other hydraulic pump is higher than the discharge pressure of the one hydraulic pump, the merging circuit is switched to the first merging position, the both discharging circuits are connected through the throttle, and both load sensing circuits are cut off. To do. In this way, by making the discharge circuits of the first and second hydraulic pumps communicate with each other through the throttle at the first merging position, all the discharge flow rates of the hydraulic pumps on the merging supply side can be supplied to the merging side. Instead, the pressure oil can be surely supplied to the actuator group on the merge supply side, and the pressure oil can be appropriately supplied to all the actuators that need to be operated, so that the work speed can be increased. Also, because of the diaphragm, the first
The independence of the load sensing control of the second hydraulic pump is maintained, and the pump discharge amount on the side having a surplus when the horsepower control of the first and second hydraulic pumps is performed can be utilized to the maximum extent.

(2) In the above (1), preferably,
The merging circuit includes a first merging line that connects the discharge circuit of the first hydraulic pump and the discharge circuit of the second hydraulic pump, the first load sensing circuit, and the second load sensing circuit. And a second merging line that connects the two merging lines, and a single merging / branching switch that is disposed on the first and second merging lines and that can switch between the merging position, the first merging position, and the second merging position. It shall include a valve.

By constructing the merging circuit with one merging / branching switching valve in this way, the structure of the merging circuit is simplified.

(3) Further, in the above (1), preferably, the merging circuit includes two merging lines connecting the discharge circuit of the first hydraulic pump and the discharge circuit of the second hydraulic pump. The two merging lines are arranged so that both of the two merging lines are shut off when switched to the merging position, and one of the two merging lines is switched when switched to the first merging position. Of the merging line and the other merging line are cut off, and when the other merging line is switched to the second merging position, the other merging line is connected and the one merging line is cut off. A valve and a check valve, which is arranged in each of the two joining lines and allows only the flow of pressure oil from the other hydraulic pump to the one hydraulic pump, are included.

As described above, by forming the merging circuit with the two merging lines and the merging / branching switching valve, and further providing a check on each of the two merging lines, it is possible to prevent the backflow due to the sudden change of the pump discharge pressure. .

(4) Further, preferably, the merging / diversion switching control means includes first maximum displacement detecting means for detecting whether or not the first hydraulic pump has reached a maximum displacement position, and A second maximum displacement detecting means for detecting whether or not the second hydraulic pump has reached the maximum displacement position, wherein the first or second hydraulic pump reaches the maximum displacement position by these detection means. If it is detected, it is determined that one of the first and second hydraulic pumps cannot supply the required flow rate of the corresponding actuator group.

As described above, whether or not the hydraulic pump cannot supply the required flow rate of the corresponding directional control valve group depends on whether the hydraulic pump reaches the maximum tilt position, not on the load sensing differential pressure. By detecting and controlling the switching of the merging circuit, a stable merging / diverting operation will not occur due to the transient change in the load sensing differential pressure due to the response delay of the load sensing control, and the switching of merging / diverting will not occur. Is obtained.

(5) Further, preferably, the merging / branching flow switching control means detects whether or not the first hydraulic pump is in a saturation state in which the discharge flow rate is insufficient with respect to the required flow rate of the corresponding directional control valve. And a second saturation detection means for detecting whether or not the second hydraulic pump is in a saturation state in which the discharge flow rate is insufficient with respect to the required flow rate of the corresponding directional control valve, When the detection means detects that the first or second hydraulic pump is in the saturation state, one of the first and second hydraulic pumps supplies the required flow rate of the corresponding actuator group. It should be judged that the condition cannot be met.

(6) Further, in the above (1), preferably, the merging / diversion switching control means is in a saturation state in which the discharge flow rate is insufficient with respect to the flow rate required by the directional control valve to which the first hydraulic pump corresponds. And a second saturation detecting means for detecting whether or not the second hydraulic pump is in a saturation state in which the discharge flow rate is insufficient with respect to the required flow rate of the corresponding directional control valve. Including the detection means, one of the first and second hydraulic pumps is in a state where it cannot supply the required flow rate of the corresponding directional control valve group, and the discharge pressure of the other hydraulic pump is In addition to being higher than the discharge pressure of one hydraulic pump, the other hydraulic pump can be operated by the first and second saturation detecting means. When it is detected that the state is not in the turation state, the merging circuit is switched to the first merging position, and the one hydraulic pump is also in a state where it cannot supply the required flow rate and the discharge of the one hydraulic pump. In addition to the pressure being higher than the discharge pressure of the other hydraulic pump, when it is detected that the other hydraulic pump is not in the saturation state, the merging circuit is switched to the second merging position.

As described above, the merging circuit is switched to the second merging position only when the hydraulic pump on the merging supply side is not in the saturation state and the discharge flow rate has a margin with respect to the required flow rate of the corresponding directional control valve group. By merging even if there is no margin, the group of actuators on the merging supply side does not become insufficient in supply flow rate, and proper merging can be performed.

(7) In the above (5) or (6), preferably, the first and second discharge amount control means are load sensing based on the pump discharge pressure, the maximum load pressure, and the pump tilt position, respectively. Load sensing control calculation means for calculating a first target pump displacement by control, and horsepower control calculation for calculating a second target pump displacement by horsepower control based on the pump discharge pressure, pump displacement angle, and engine speed. Means and means for selecting the smaller one of the first and second target pump displacements and controlling the corresponding hydraulic pump, wherein the first and second saturation detection means include:
It is assumed that the first target pump displacement and the second target pump displacement are compared, and whether the hydraulic pump is in a saturation state is detected by comparing the both target pump displacements.

In this way, by detecting whether the hydraulic pump is in the saturation state by comparing the target pump displacements, the merging circuit is moved to the branch position before the hydraulic pump on the merging supply side is actually in the saturation state. It can be switched, and stable merging / shunting action can be obtained.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIGS.

Referring to FIG. 1, a hydraulic drive system according to a first embodiment of the present invention includes a hydraulic pump 1 driven by a prime mover 38, a hydraulic actuator 2 driven by pressure oil discharged from the hydraulic pump 1. Hydraulic actuator group including 3 (hereinafter referred to as hydraulic actuator groups 2 and 3), hydraulic pump 1 and hydraulic actuator groups 2 and 3
Between the hydraulic pump 1 and the hydraulic actuator groups 2 and 3 for controlling the flow rate of the hydraulic oil and switching the hydraulic oil feeding direction. A load sensing circuit 27 including check valves 27a and 27b for detecting the highest load pressure (hereinafter referred to as maximum load pressure) of the hydraulic actuator groups 2 and 3, and the load sensing circuit 27. The pressure control including the pressure control valves 43 and 44 for controlling the outlet pressure of the meter-in variable throttles incorporated in each of the directional control valve groups 2 and 3 to be the same as the maximum load pressure. And a valve group (hereinafter referred to as pressure control valve groups 43 and 44). Further, similarly to this, a hydraulic actuator group that includes a hydraulic pump 6 driven by the prime mover 38 and hydraulic actuators 7, 8 driven by pressure oil discharged from the hydraulic pump 6 (hereinafter, hydraulic actuator groups 7, 8). Is provided between the hydraulic pump 6 and the hydraulic actuator groups 7 and 8 to control the flow rate of the pressure oil sent from the hydraulic pump 6 to the hydraulic actuator groups 7 and 8 and to switch the pressure oil feeding direction. Directional switching valve group including valves 9 and 10 (hereinafter referred to as directional switching valve group 9 and 10) and hydraulic actuator groups 7 and 8
Of the load sensing circuit 28 including the check valves 28a and 28b for detecting the highest load pressure (hereinafter, referred to as the maximum load pressure) of the load sensing circuit 28, and the maximum load pressure detected by the load sensing circuit 28 act to operate the directional control valve group 9, Pressure control valves 45, 46 for controlling the outlet pressures of the meter-in variable throttles built in each of 10 to be the same as the maximum load pressure.
And a pressure control valve group (hereinafter, referred to as pressure control valve groups 45 and 46).

The hydraulic pump 1 is of a variable displacement type and is provided with an LS control valve 20 and a servo mechanism 29 as its discharge amount control means. The LS control valve 20 is connected to the pilot line 18 branching from the discharge circuit 11 of the hydraulic pump 1 and the load sensing circuit 27, and is controlled by a servo mechanism 29 so that the discharge pressure of the hydraulic pump 1 becomes higher than the maximum load pressure by a predetermined value. The tilting of the hydraulic pump 1 is controlled.

The hydraulic pump 6 is also of a variable displacement type, and has an LS control valve 24 and a servo mechanism 42 as its discharge amount control means. The LS control valve 24 is connected to the pilot line 23 branching from the discharge circuit 12 of the hydraulic pump 6 and the load sensing circuit 28, and is controlled by the servo mechanism 42 so that the discharge pressure of the hydraulic pump 6 becomes higher than the maximum load pressure by a predetermined value. The tilting of the hydraulic pump 6 is controlled.

Between the discharge circuit 11 of the hydraulic pump 1 and the discharge circuit 12 of the hydraulic pump 6 and the load sensing circuit 27.
Between the load sensing circuit 28 and the load sensing circuit 28.
Is provided. The merging circuit 100 includes both discharge circuits 11,
It is composed of a merging line 13 for connecting 12 together, a merging line 70 for connecting both load sensing circuits 27, 28, and a merging / branching switching valve 14 installed on the merging lines 13, 70. The merging / shunting switching valve 14 is for both discharge circuits 11,
12 is cut off and both load sensing circuits 27 and 28 are cut off.
0 through both load sensing circuits 27, 2
8 and a first merging position b for shutting off 8 and both discharge circuits 11, 1.
2 are directly connected and both load sensing circuits 27,
4 that can be switched to the second merging position c that communicates 28
It is a port 3 position switching valve.

Further, the merging / dividing flow switching valve 14 is a hydraulic pilot switching system, and as the switching means, the hydraulic pilot pump 16 and the load sensing differential pressure detecting valve 6 are used.
There is provided a merging / diversion switching control circuit 200 composed of 3, 64, maximum tilt detection valves 61, 62, circuit pressure comparison detection valve 60, and pilot lines 80 to 88 connecting them.

In the combined / diversion switching control circuit 200, the load sensing differential pressure detection valve 63 is a valve which operates by the balance between the differential pressure between the discharge pressure of the hydraulic pump 6 and the maximum load pressure of the load sensing circuit 28 and the spring 65. Yes, when the differential pressure between the pump discharge pressure and the maximum load pressure is maintained at the set value of the spring 65 (load sensing set differential pressure), it is in the first position on the left side of the drawing, and the pilot from the pilot pump 16 The pressure is transmitted to the maximum tilt detection valve 61, and when the differential pressure becomes smaller than the set value of the spring 65, the pressure is switched to the second position on the right side in the drawing, and the pilot pump 1
Shut off pilot pressure from 6.

The load sensing differential pressure detection valve 64 is also a valve that operates by the balance between the differential pressure between the discharge pressure of the hydraulic pump 1 and the maximum load pressure of the load sensing circuit 27 and the spring 66, and the pump discharge pressure and maximum load. When the pressure difference from the pressure is kept at the set value of the spring 66 (load sensing set pressure difference), it is in the first position on the right side of the drawing, and the pilot pressure from the pilot pump 16 is set to the maximum tilt detection valve 6
When the differential pressure becomes smaller than the set value of the spring 66, it is switched to the second position on the left side in the drawing, and the pilot pressure from the pilot pump 16 is shut off.

The maximum tilt detection valve 61 is a valve that operates when linked to the tilt of the hydraulic pump 1 when the hydraulic pump 1 reaches the maximum tilt position, and is shown before the hydraulic pump 1 reaches the maximum tilt position. At the first position on the right side, the pilot pressure transmitted from the load sensing differential pressure detection valve 63 is shut off,
When the hydraulic pump 1 reaches the maximum tilt position, the second pump on the left side in the figure
Position, the load sensing differential pressure detection valve 63
The pilot pressure transmitted from the circuit pressure comparison detection valve 60
Tell

Similarly, the maximum displacement detection valve 62 is also used for the hydraulic pump 6.
Is a valve that is linked to the tilting of the hydraulic pump 6 when it reaches the maximum tilting position, and is located at the first position on the left side in the figure before the hydraulic pump 6 reaches the maximum tilting position. The pilot pressure transmitted from the detection valve 64 is shut off, and when the hydraulic pump 6 reaches the maximum tilt position, it switches to the second position on the right side in the figure, and the pilot pressure transmitted from the load sensing differential pressure detection valve 64 is switched to the circuit. This is transmitted to the pressure comparison detection valve 60.

The circuit pressure comparison / detection valves 60 are hydraulic pumps 1 and 6.
Are operated by a differential pressure between the discharge circuits 11 and 12 of FIG.
When the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1, the position is switched to the first position on the right side in the figure, and the pilot pressure from the maximum displacement detection valve 61 is used as a command signal.
When the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6, it is switched to the second position on the left side of the drawing, when it is transmitted to the drive unit of the diversion switching valve 14 on the first merging position switching side.
The pilot pressure from the maximum displacement detection valve 62 is transmitted as a command signal to the drive unit of the merging / branching switching valve 14 on the second merging position switching side.

The switching control of the merging / branching switching valve 14 by the merging / branching switching control circuit 200 will be described below.

When the hydraulic pump 1 reaches the maximum tilt position, the maximum tilt detection valve 6 linked to the tilt of the hydraulic pump 1
1 switches to the second position on the left side of the drawing, and the pressure from the load sensing differential pressure detection valve 63 is compared with the circuit pressure comparison detection valve 60.
Tell Further, the load sensing differential pressure detection valve 63 is
There is a margin in the discharge flow rate with respect to the required flow rate of the directional control valve groups 9 and 10 to which the hydraulic pump 6 corresponds, that is, the hydraulic pump 6 is not in the saturation state, and the differential pressure between the pump discharge pressure and the maximum load pressure is the spring 65. Is set to the first position on the left side in the drawing, the pressure from the pilot pump 16 is transmitted to the maximum tilt detection valve 61. Further, when the pressure in the pilot line 23 is higher than that in the pilot line 18, that is, when the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1, the circuit pressure comparison detection valve 60 is located at the first position on the right side of the drawing. The pressure oil from the maximum tilt detection valve 61 is switched to the position, and the pressure oil from the maximum tilt detection valve 61 is transmitted to the drive unit of the merging / branching switching valve 14 on the first merging position switching side. With this,
The diversion switching valve 14 is switched to the first merging position b provided with the throttle 50, and the discharge flow rate of the hydraulic pump 6 is changed to the hydraulic pump 1.
Is supplied to the ejection circuit 11 on the side. At this time, the load sensing circuit 27 and the load sensing circuit 28 are cut off, and the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 communicate with each other through the throttle 50, so that the LS control valve 2 of the hydraulic pumps 1 and 6 is connected.
Independence of load sensing control by 0, 24 is maintained. Further, since the discharge flow rate of the hydraulic pump 6 is supplied to the hydraulic pump 1 side via the throttle 50, the entire discharge flow rate of the hydraulic pump 6 is not supplied to the hydraulic pump 1 side.
A part is supplied to the hydraulic pump 1 side, the rest is the hydraulic pump 6
It is supplied to the side actuator groups 7 and 8. For this reason,
The merging can be performed while reliably supplying the pressure oil to the actuator groups 7 and 8 belonging to the hydraulic pump 6 on the merging supply side.

When the pressure in the pilot line 18 is higher than that in the pilot line 23, that is, when the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6,
The circuit pressure comparison detection valve 60 switches to the second position on the left side in the drawing, and transmits the pressure oil from the maximum tilt detection valve 61 to the drive unit of the merging / diverting switching valve 14 on the second merging position switching side. As a result, the merging / branching switching valve 14 does not pass through the throttle 50.
Is switched to the merging position c. At this time, since the load sensing circuit 27 and the load sensing circuit 28 are in communication with each other, the hydraulic pumps 1 and 6 are both in the entire actuator group 2
The load sensing control is performed by the maximum load pressure of 3, 7, 8 and the total discharge flow rate of the two pumps 1, 6 supplies the pressure oil to all the actuator groups 2, 3, 7, 8.

Similarly, when the hydraulic pump 6 reaches the maximum tilt position, the maximum tilt detection valve 62 linked to the tilt of the hydraulic pump 6 is switched to the second position on the right side in the drawing,
The pressure from the load sensing differential pressure detection valve 64 is transmitted to the circuit pressure comparison detection valve 60. The load sensing differential pressure detection valve 64 includes the directional control valve group 4 to which the hydraulic pump 1 corresponds.
There is a margin in the discharge flow rate with respect to the required flow rate of 5, that is, when the hydraulic pump 1 is not in the saturation state and the differential pressure between the pump discharge pressure and the maximum load pressure is maintained at the set value of the spring 66, It is located at the first position on the right side and transmits the pressure from the pilot pump 16 to the maximum tilt detection valve 62. Further, the circuit pressure comparison and detection valve 60, when the pressure of the pilot line 18 is higher than that of the pilot line 23,
That is, when the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6, the hydraulic pressure is switched to the second position on the left side of the drawing, and the pressure oil from the maximum tilt detection valve 62 is switched to the diverting / diverting valve 1
4 to the drive unit on the first merging position switching side. As a result, the diverging / diverting switching valve 14 is switched to the first convergence position b provided with the throttle 50, and supplies the discharge flow rate of the hydraulic pump 1 to the discharge circuit 12 of the hydraulic pump 16. At this time, the load sensing circuit 27 and the load sensing circuit 28 are cut off, and the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 communicate with each other through the throttle 50, so that the hydraulic pumps 1 and 6 have L levels.
Independence of the load sensing control by the S control valves 20 and 24 is maintained. Further, the discharge flow rate of the hydraulic pump 1 is the throttle 5
Since it is supplied to the hydraulic pump 6 side via 0, the entire discharge flow rate of the hydraulic pump 1 is not supplied to the hydraulic pump 6 side, a part is supplied to the hydraulic pump 6 side, and the rest is supplied to the hydraulic pump 6. It is supplied to the actuator groups 2 and 3 on the first side.
Therefore, the merging can be performed while surely supplying the pressure oil to the actuator groups 2 and 3 belonging to the hydraulic pump 1 on the merging supply side.

When the pressure in the pilot line 23 is higher than that in the pilot line 18, that is, when the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1,
The circuit pressure comparison detection valve 60 is switched to the first position on the right side in the drawing, and the pressure oil from the maximum tilt detection valve 62 is transmitted to the drive unit of the merging / branching switching valve 14 on the second merging position switching side. As a result, the merging / branching switching valve 14 does not pass through the throttle 50.
And the discharge flow rate of the hydraulic pump 1 is supplied to the discharge circuit 12 on the hydraulic pump 6 side. At this time, since the load sensing circuit 27 and the load sensing circuit 28 communicate with each other, the hydraulic pumps 1 and 6 are both load-sensing-controlled by the maximum load pressure of all the actuator groups 2, 3, 7, and 8. 1,
Based on the total discharge flow rate of 6, all actuator groups 2, 3, 7,
Provides 8 pressure oil supply.

If the conditions other than those mentioned above are satisfied,
The diversion switching valve 14 is kept at the diversion position a.

Further, in the present embodiment, as described above, since the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 are communicated with each other via the throttle 50 at the first merging position of the merging / branching switching valve 14, the hydraulic pressure is changed. Independence of the load sensing control by the LS control valves 20, 24 of the pumps 1, 6 is maintained. The operation in this regard will be described below.

FIG. 2 shows an example of a conventional combining / splitting system as a comparative example. In this merging / branching method, the merging / branching switching valve 114 of the merging circuit 1100 does not have a throttle at the merging position, and at the merging position of the merging / branching switching valve 114, the load sensing circuits 27 and 28 are also controlled by the load sensing pressure switching valve 41. It is configured to communicate. In addition, the same components as those shown in FIG. 1 of the present embodiment are designated by the same reference numerals. Reference numeral 15 is an electromagnetic switching valve, 17 is a controller, 19 and 20 are TVC valves, and 26 and 27 are operating levers. Note that this combining / splitting method is, for example, the actual Kaihei 6-40.
No. 406 publication.

FIG. 3 shows changes in the pump discharge flow rate when the diverting position is switched to the merging position in the merging / branching system shown in FIG.

In FIG. 2, for example, the hydraulic pumps 1 and 6
It is assumed that the discharge flow rate is controlled to be limited by half the horsepower distribution by the total horsepower control, and the flow rate is discharged by the load sensing control in this state. Here, the hydraulic pump 1 discharges a flow rate of α at the maximum tilt position A point at a pump discharge pressure of 100 Kg / cm ² shown in FIG. 3, and the hydraulic pump 6 has a pump discharge pressure of 250 / c higher than that of the hydraulic pump 1.
It is assumed that the system is operating by discharging the flow rate of β at point B within the horsepower flow restriction range of m ² . At this time, the required flow rate of the directional control valve groups 4 and 5 on the hydraulic pump 1 side is α + γ
In this case, this flow rate is supplemented by the merging of the hydraulic pumps 1 and 26, and the merging / branching switching valve 14 is switched to the merging position. In this case, there is no throttle at the merging position, and the maximum load pressures of the load sensing circuits 27 and 28 are the same due to the switching of the load sensing pressure switching valve 41, so both pumps have a discharge pressure of 250 Kg / cm ² and hydraulic pressure. The pump 1 discharges the flow rate at the point C shown in FIG. 3, and the hydraulic pump 6 discharges the flow rate at the point D shown in FIG. 3 to operate the system. Therefore, the sum of the discharge flow rates of the hydraulic pumps 1 and 6 is δ, but only a flow rate smaller than α + β, which is the total flow rate of the discharge flow rate α of the hydraulic pump 1 and the discharge flow rate β of the hydraulic pump 6 at the time of split flow, is supplied. The phenomenon of not being obtained occurs. For this reason, the required flow rate on the hydraulic pump 1 side cannot be satisfied, and the required flow rate on the hydraulic pump 6 side cannot be satisfied. Therefore,
If there is a difference between the maximum load pressures on the hydraulic pump 1 side and the hydraulic pump 6 side, the effect of merging cannot be obtained.

FIG. 4 shows changes in the pump discharge flow rate when the diverging position is switched to the merging position in the merging / branching method according to the present invention. Also in this case, it is assumed that the hydraulic pumps 1 and 6 are controlled to limit the discharge flow rate by half horsepower distribution by full horsepower control.

In FIG. 4, the hydraulic pump 1 has a pump discharge pressure of 100 Kg / cm ² and α at the maximum tilt position A point.
It is assumed that the hydraulic pump 6 discharges the flow rate β at a point B within the horsepower flow rate restriction range at a pump discharge pressure of 250 kg / cm ² higher than the hydraulic pump 1 to operate the system. At this time, when the required flow rate of the direction switching valve groups 4 and 5 on the hydraulic pump 1 side is α + γ, this flow rate is supplemented by the confluence of the hydraulic pumps 1 and 6, and the converging / diverting switching valve 14 is connected to the first confluence valve. Switch to position. In this case, since the throttle 50 is provided at the first merging position and the load sensing circuits 27, 28 are separated, the independence of the load sensing control by the LS control valves 20, 24 of the hydraulic pumps 1, 6 is maintained. Be drunk Therefore, the hydraulic pump 1
Discharge pressure of 100 Kg / cm ² before merging, the discharge flow rate α of the hydraulic pump 1 does not decrease, and the hydraulic pump 6 shows the discharge pressure limit of 250 Kg / cm ² shown in FIG. By increasing the discharge flow rate for γ and merging the increased amount into the discharge circuit 11 on the hydraulic pump 1 side, the hydraulic pump 1 discharges at the maximum tilt position A point at point C shown in FIG. It is as if the flow rate of α + γ which is equal to or higher than the flow rate α is being discharged.

On the other hand, in FIG. 5, the hydraulic pump 1 discharges a flow rate of α at the maximum tilt position A at a pump discharge pressure of 100 Kg / cm ² , and the hydraulic pump 6 has a pump discharge pressure of 50 Kg / lower than that of the hydraulic pump 1. It is assumed that the system is operated by discharging the flow rate of β at point B within the horsepower flow restriction range of cm ² . At this time, when the required flow rate of the directional control valve groups 4 and 5 on the hydraulic pump 1 side is α + γ, the flow rate is supplemented by the merging of the hydraulic pumps 1 and 6,
The diversion switching valve 14 is switched to the second merging position. In this case, since there is no throttle at the second merging position and the load sensing circuits 27 and 28 are in communication, the discharge pressure of the hydraulic pump 6 rises to 100 Kg / cm ² at point D shown in FIG. At the point D, the discharge amount for γ is increased within the horsepower limit range, and the increased flow rate is merged with the discharge circuit 11 on the hydraulic pump 1 side, so that the hydraulic pump 1 at the point C shown in FIG. It is as if the flow rate of α + γ which is equal to or higher than the discharge flow rate α at the maximum tilt position A is discharged.

As described above, according to this embodiment, the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 are communicated with each other through the throttle 50 at the first merging position of the merging / branching switching valve 14, so that the merging supply is performed. The discharge flow rate of the hydraulic pump on the side is not supplied to the merged side, the pressure oil is surely supplied to the actuator group on the merge supply side, and the pressure oil is appropriately supplied to all actuators that need to be operated. Yes, you can perform appropriate complex operations and speed up the work.

Further, at the first merging position of the merging / branching switching valve 14, the discharge circuit 1 of the hydraulic pumps 1 and 6 via the throttle 50.
Since 1 and 12 are communicated with each other, the independence of the load sensing control by the LS control valves 20 and 24 of the hydraulic pumps 1 and 6 is maintained, and the pump discharge amount on the side with a reserve when the hydraulic pumps 1 and 6 are horsepower controlled. Can be used to the maximum.

Further, whether or not the hydraulic pump 1 or 6 cannot supply the required flow rate of the corresponding directional control valve group is determined by the hydraulic pump 1 or 6 at the maximum tilt position, not by the load sensing differential pressure. Depending on whether or not it has reached, the merging / diversion switching valve 14 is switched and controlled. Therefore, the merging / diversion switching may be performed due to a transient change in the load sensing differential pressure due to a response delay of the load sensing control. It is possible to obtain stable merging / separating action.

Further, since the hydraulic pump on the merging supply side is not in the saturation state and the discharge flow rate has a margin with respect to the required flow rate of the corresponding directional control valve group, the merging circuit 100 is switched to the second merging position. By merging regardless of the absence, the actuator group on the merging supply side does not become insufficient in supply flow rate, and proper merging can be performed.

Since the merging circuit 100 is composed of one merging / branching switching valve 14, the structure of the merging circuit is extremely simple.

A second embodiment of the present invention will be described with reference to FIG. In the drawing, members that are the same as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof will be omitted.

In FIG. 6, the discharge circuit 1 of the hydraulic pump 1
1 and the discharge circuit 12 of the hydraulic pump 6, and between the load sensing circuit 27 and the load sensing circuit 28, a merging circuit 100A is provided. Confluence circuit 100A
Is two merging lines 1 connecting both discharge circuits 11 and 12.
3a, 13b, two merging lines 70a, 70b connecting both load sensing circuits 27, 28, a merging / branching switching valve 14A installed on the merging lines 13a, 13b and 70a, 70b, and on the merging line 13a. Check valve which is installed on the merging line 13b and the throttle switching valve 55 which is installed on the merging line 13b, and which allows only the flow of pressure oil from the load sensing circuit 27 to the load sensing circuit 28. The valve 53 and a check valve 54 provided on the merging line 70b to allow only the flow of pressure oil from the load sensing circuit 28 to the load sensing circuit 27.

The merging / branching switching valve 14A is used for the merging line 13
a and 13b are cut off, and the merging line 70a on the side of the load sensing circuit 27 and the load sensing circuit 2
While cutting off the merging lines 70b on the 8 side,
The diverging position a connecting the merging line 70b on the side of the load sensing circuit 27 and the merging line 70a on the side of the load sensing circuit 28 to the tank, the merging line 13a and the merging line 70a, and the merging line 13b.
And a first merging position b for blocking the merging line 70b, and a second merging position c for connecting the merging line 13b and the merging line 70b and blocking the merging line 13a and the merging line 70a, respectively. 8
It is a port 3 position switching valve.

Further, the merging / diversion switching valve 14A is of the hydraulic pilot switching system as in the first embodiment, and the merging / diversion switching control circuit 200 is used as the switching means.
A is provided. Combination / shunt switching control circuit 200
A has a configuration in which a circuit pressure comparison detection valve 60 is employed from the merge / shunt switch control circuit 200 shown in FIG. The pressure transmitted to the first merge position switching side drive unit of the valve 14A and the pressure output from the maximum displacement detection valve 62 is used as a direct command signal as the second merge position switch side drive unit of the merge / shunt switch valve 14A. Conveyed to.

The throttle switching valve 55 has a first position on the upper side in the drawing that allows the merging line 13a to communicate with each other as it is, and a second position on the lower side in the drawing that allows the merging line 13a to communicate with each other via the throttle 50a.
, And the throttle switching valve 56 is also connected to the first position on the lower side in the drawing where the merging line 13b is communicated as it is, and the converging line 13b is connected via the restrictor 50b. To communicate with the second
This is a two-port two-position switching valve that can be switched between the two positions. The throttle switching valve 55 has a built-in check valve 51 that allows only the flow of the hydraulic oil from the hydraulic pump 6 to the hydraulic pump 1 at the second position, and the throttle switching valve 56 has the hydraulic pump 1 at the second position. A check valve 52 that allows only the flow of the pressure oil from the pump to the hydraulic pump 6 is built in.

Further, the throttle switching valves 55, 56 are of the hydraulic pilot switching type and are constructed as circuit pressure comparison detection valves. That is, the throttle switching valve 55 operates by the pressure difference between the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6,
When the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6, it switches to the first position on the upper side in the drawing, and when the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1, it moves to the first position on the lower side in the drawing. 2 position, throttle switching valve 5
6 operates by the pressure difference between the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6, and switches to the lower first position in the drawing when the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1. When the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6, it switches to the second position on the upper side in the drawing.
That is, the pilot lines that connect the both-end driving portions of the throttle switching valves 55 and 56 to the associated discharge circuits 11 and 12 serve as switching means for these, and a merge / divide flow switching control circuit 200A.
Is part of.

In the present embodiment configured as described above, when the hydraulic pump 1 reaches the maximum tilt position, the maximum tilt detection valve 61 switches to the second position on the left side in the drawing, and the load sensing differential pressure detection valve The pressure from 63 is transmitted to the drive unit on the first merging position switching side of the merging / branching switching valve 14A.
In addition, the load sensing differential pressure detection valve 63 has a margin in the discharge flow rate with respect to the required flow rate of the direction switching valve groups 9 and 10 to which the hydraulic pump 6 corresponds, that is, the hydraulic pump 6 is not in the saturation state and the pump discharge pressure is When the differential pressure between the maximum load pressure and the maximum load pressure is maintained at the set value of the spring 65, the pressure is at the first position on the left side of the drawing, and the pressure from the pilot pump 16 is transmitted to the maximum tilt detection valve 61. For this reason,
The diversion switching valve 14A includes the merging line 13a and the merging line 70.
It is switched to the first merging position b where the a is communicated with each other. In addition, compared with the discharge pressure of the hydraulic pump 1, the hydraulic pump 6
When the discharge pressure is high, the throttle switching valve 55 switches to the second position provided with the throttle 50a. Thus, the merge / divide flow switching valve 14A and the throttle switching valve 55 allow the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 to communicate via the throttle 50a, and the discharge flow rate of the hydraulic pump 6 to the discharge circuit 11 on the hydraulic pump 1 side. Supply.

At this time, the load sensing circuit 27 and the load sensing circuit 28 are shut off by the check valve 53, and the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 are throttled.
Since the hydraulic pumps 1 and 6 are communicated with each other, the independence of the load sensing control by the LS control valves 20 and 24 of the hydraulic pumps 1 and 6 is maintained. The discharge flow rate of the hydraulic pump 6 is the throttle 50a.
Is not supplied to the hydraulic pump 1 side, but a part is supplied to the hydraulic pump 1 side, and the rest is supplied to the hydraulic pump 6 side. It is supplied to the side actuator groups 7 and 8. Therefore, the merging can be performed while surely supplying the pressure oil to the actuator groups 7 and 8 belonging to the hydraulic pump 6 on the merging supply side. Further, since the gas is supplied through the check valve 51, it is possible to prevent backflow due to a sudden change in pump discharge pressure.

When the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6, the throttle switching valve 55 causes the throttle 5
It switches to the first position not through 0a. At this time, the check valve 53 opens and the load sensing circuit 27 and the load sensing circuit 28 communicate with each other, so that the hydraulic pump 1,
6 is load-sensing controlled by the maximum load pressure of all actuator groups 2, 3, 7, and 8.
The total discharge flow rate of the two pumps 1 and 6 supplies the pressure oil to all the actuator groups 2, 3, 7, and 8.

Similarly, when the hydraulic pump 6 reaches the maximum tilting position, the maximum tilting detection valve 62 switches to the second position on the right side in the drawing, and the pressure from the load sensing differential pressure detection valve 64 is joined or split. The signal is transmitted to the drive unit on the second merging position switching side of the switching valve 14A. Further, the load sensing differential pressure detection valve 64 includes the direction switching valve groups 4, 5 to which the hydraulic pump 1 corresponds.
When the hydraulic pump 1 is not in the saturation state and the differential pressure between the pump discharge pressure and the maximum load pressure is maintained at the set value of the spring 66, the discharge flow rate has a margin with respect to the required flow rate of Is in the first position, and transmits the pressure from the pilot pump 16 to the maximum tilt detection valve 62. Therefore, the merging / shunting switching valve 14A is connected to the merging line 13
The second merging position c is switched to connect the b and the merging line 70b. When the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6, the throttle switching valve 56 switches to the second position provided with the throttle 50b. As a result, the merge / divide flow switching valve 13A and the throttle switching valve 56 communicate the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 via the throttle 50b, and reduce the discharge flow rate of the hydraulic pump 1 to the hydraulic pump 6
Is supplied to the ejection circuit 11 on the side.

At this time, the load sensing circuit 27 and the load sensing circuit 28 are shut off by the check valve 54, and the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 are closed by the throttle 5.
Since the communication is made via 0b, the independence of the load sensing control by the LS control valves 20, 24 of the hydraulic pumps 1, 6 is maintained. Further, the discharge flow rate of the hydraulic pump 1 is the throttle 50b.
Is not supplied to the hydraulic pump 6 side, a part of the discharge flow rate of the hydraulic pump 1 is supplied to the hydraulic pump 6 side, and the rest is supplied to the hydraulic pump 1 side. Is supplied to the side actuator groups 2 and 3. Therefore, the merging can be performed while surely supplying the pressure oil to the actuator groups 2 and 3 belonging to the hydraulic pump 1 on the merging supply side. Further, since the gas is supplied through the check valve 52, it is possible to prevent backflow due to a sudden change in pump discharge pressure.

Further, when the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1, the throttle switching valve 56 causes the throttle 5
It switches to the first position not through 0b. At this time, the check valve 54 opens and the load sensing circuit 27 and the load sensing circuit 28 communicate with each other, so that the hydraulic pump 1,
6 is load-sensing controlled by the maximum load pressure of all actuator groups 2, 3, 7, and 8.
The total discharge flow rate of the two pumps 1 and 6 supplies the pressure oil to all the actuator groups 2, 3, 7, and 8.

When the conditions other than those mentioned above are satisfied,
The diversion switching valve 14A is kept at the diversion position a.

Therefore, according to this embodiment, the same effect as that of the first embodiment can be obtained, and the merging line 1
Since check valves 51 and 52 are provided in 3a and 13b, it is possible to prevent backflow due to a sudden change in pump discharge pressure.

A third embodiment of the present invention will be described with reference to FIG. In the figure, the same members as those shown in FIGS. 1 and 6 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 7, the discharge circuit 1 of the hydraulic pump 1
1 and the discharge circuit 12 of the hydraulic pump 6 and between the load sensing circuit 27 and the load sensing circuit 28, a merging circuit 100B is provided. Junction circuit 100B
Is the merging circuit 100 in the second embodiment shown in FIG.
In A, instead of the merging / shunting switching valve 14A, the first and second
It has a configuration in which the diversion switching valves 14B and 14C are provided.

The first merging / branching switching valve 14B shuts off the merging line 13a and the merging line 70a, respectively, and connects the merging line 13b and the merging line 70b.
Can be switched to a merging position a1 on the upper side in the figure where the merging line is connected to the tank and a merging position b on the lower side in the drawing for connecting the merging line 13a and connecting the merging line 70a to the tank and blocking the merging line 13b and the merging line 70b respectively. It is a simple 8-port 2-position switching valve.

The second merging / separating flow switching valve 14C is also similarly
A diverting position a2 on the lower side in the drawing, which connects the merging line 13a and the merging line 70a to the tank, and blocks the merging line 13b and the merging line 70b, respectively.
This is an eight-port two-position switching valve capable of blocking the merging line 13a and the merging line 70a, respectively, and connecting the merging line 13b and connecting the merging line 70b to the tank to a merging position c on the upper side in the drawing.

Further, the first and second merging / separating flow switching valve 14
Similar to the first embodiment, B and 14C are hydraulic pilot switching systems and are configured as load sensing differential pressure detection valves. That is, the first combination / dividing flow switching valve 14B operates by the balance between the differential pressure between the discharge pressure of the hydraulic pump 1 and the maximum load pressure of the load sensing circuit 27 and the spring 90, and the pump discharge pressure and the maximum load pressure. Is kept at the set value of the spring 90 (load sensing set differential pressure), it is in the shut-off position a1 on the upper side of the drawing, and when the differential pressure becomes smaller than the set value of the spring 90, the merging on the lower side of the drawing. Switch to position b. In addition, the second combination / diversion valve 14C also operates by the balance between the differential pressure between the discharge pressure of the hydraulic pump 6 and the maximum load pressure of the load sensing circuit 28 and the spring 91, and the pump discharge pressure and the maximum load pressure. When the pressure difference between and is maintained at the set value of the spring 91 (load sensing set pressure difference), the diversion position a on the lower side of the drawing is shown.
2 and the differential pressure becomes smaller than the set value of the spring 91, it switches to the merging position c on the upper side in the drawing. That is, the pilot line connecting the both-end drive parts of the first and second merge / divide switching valves 14B and 14C to the associated discharge circuit 11 or 12 and the load sensing circuit 28 or 28 serves as a means for switching between them. It constitutes a control circuit.

In the present embodiment having the above-described structure, when the hydraulic pump 1 is in the saturation state and the hydraulic pump 1 cannot supply the required flow rate of the corresponding directional control valves 4 and 5, the pump discharge is performed. The pressure difference between the pressure and the maximum load pressure becomes smaller than the set value of the spring 90, and the first
The merging / branching switching valve 14B is switched to the merging position b on the lower side in the drawing. When the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1, the throttle switching valve 55 causes the throttle 50a to move.
Switch to a second position with. For this reason, the first combination / diversion switching valve 14C and the throttle switching valve 55 connect the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 via the throttle 50a, and the discharge flow rate of the hydraulic pump 6 from the hydraulic pump 1 side. Supply to the discharge circuit 11.

At this time, the load sensing circuit 27 and the load sensing circuit 28 are shut off by the check valve 53, and the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 are throttled.
Since the hydraulic pumps 1 and 6 are communicated with each other, the independence of the load sensing control by the LS control valves 20 and 24 of the hydraulic pumps 1 and 6 is maintained. The discharge flow rate of the hydraulic pump 6 is the throttle 50a.
Is not supplied to the hydraulic pump 1 side, but a part is supplied to the hydraulic pump 1 side, and the rest is supplied to the hydraulic pump 6 side. It is supplied to the side actuator groups 7 and 8. Therefore, the merging can be performed while surely supplying the pressure oil to the actuator groups 7 and 8 belonging to the hydraulic pump 6 on the merging supply side. Further, since the gas is supplied through the check valve 51, it is possible to prevent backflow due to a sudden change in pump discharge pressure.

When the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6, the throttle switching valve 55 moves the throttle 5
It switches to the first position not through 0a. At this time, the check valve 53 opens and the load sensing circuit 27 and the load sensing circuit 28 communicate with each other, so that the hydraulic pump 1,
6 is load-sensing controlled by the maximum load pressure of all actuator groups 2, 3, 7, and 8.
The total discharge flow rate of the two pumps 1 and 6 supplies the pressure oil to all the actuator groups 2, 3, 7, and 8.

Similarly, when the hydraulic pump 6 is in a saturation state and the hydraulic pump 6 cannot supply the required flow rate of the directional control valves 9 and 10, the difference between the pump discharge pressure and the maximum load pressure is increased. The pressure becomes smaller than the set value of the spring 91, and the second merging / branching switching valve 14C is switched to the merging position c on the upper side in the drawing. Further, when the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6, the throttle switching valve 56 switches to the second position provided with the throttle 50b. Therefore, the second combination / diversion switching valve 14C and the throttle switching valve 56 are connected to the discharge circuits 11 of the hydraulic pumps 1 and 6,
12 are communicated with each other through the throttle 50b, and the discharge flow rate of the hydraulic pump 1 is supplied to the discharge circuit 11 on the hydraulic pump 6 side.

At this time, the load sensing circuit 27 and the load sensing circuit 28 are shut off by the check valve 54, and the discharge circuits 11 and 12 of the hydraulic pumps 1 and 6 are throttled.
Since the communication is made via 0b, the independence of the load sensing control by the LS control valves 20, 24 of the hydraulic pumps 1, 6 is maintained. Further, the discharge flow rate of the hydraulic pump 1 is the throttle 50b.
Is not supplied to the hydraulic pump 6 side, a part of the discharge flow rate of the hydraulic pump 1 is supplied to the hydraulic pump 6 side, and the rest is supplied to the hydraulic pump 1 side. Is supplied to the side actuator groups 2 and 3. Therefore, the merging can be performed while surely supplying the pressure oil to the actuator groups 2 and 3 belonging to the hydraulic pump 1 on the merging supply side. Further, since the gas is supplied through the check valve 52, it is possible to prevent backflow due to a sudden change in pump discharge pressure.

When the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1, the throttle switching valve 56 causes the throttle 5
It switches to the first position not through 0b. At this time, the check valve 54 opens and the load sensing circuit 27 and the load sensing circuit 28 communicate with each other, so that the hydraulic pump 1,
6 is load-sensing controlled by the maximum load pressure of all actuator groups 2, 3, 7, and 8.
The total discharge flow rate of the two pumps 1 and 6 supplies the pressure oil to all the actuator groups 2, 3, 7, and 8.

When the conditions other than those mentioned above are satisfied, the first
And the second merging / branching switching valves 14B and 14C at the diverting position a.
Keep at 1, a2.

Therefore, according to this embodiment, the same effect as that of the second embodiment can be obtained, and the effect of simplifying the merging / diversion switching control circuit can be obtained. Also, in this embodiment, when both circuits are in the saturation state, the merge / shunt switch valve 14B is at the position b and the merge / shunt switch valve 14C is at the position c. Can be kept. As a result, an appropriate composite operation can be performed.

A fifth embodiment of the present invention will be described with reference to FIGS. In the figure, the same members as those shown in FIGS. 1 and 6 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 8, the discharge circuit 1 of the hydraulic pump 1
1 and the discharge circuit 12 of the hydraulic pump 6, and between the load sensing circuit 27 and the load sensing circuit 28, a merging circuit 100C is provided. Junction circuit 100C
Is a merging / branching switching valve 14a and a throttle switching valve 55 provided on a merging line 13 that connects both discharge circuits 11 and 12.
C / 56C and a merging / shunting switching valve 1 provided on a merging line 70 connecting both load sensing circuits 27, 28.
4b.

The combination / division switching valve 14a is provided for both discharge circuits 11,
It is a 2-port 2-position switching valve that can switch between a diversion position that shuts off 12 and a merging position that allows both discharge circuits 11 and 12 to communicate with each other. The merging / diversion switching valve 14b also shuts off both load sensing circuits 27 and 28. It is a 2-port 2-position switching valve capable of switching between a diversion position and a confluence position where both load sensing circuits 27 and 28 communicate with each other. Further, the throttle switching valves 55C and 56C are connected to the discharge circuits 11 and 12 respectively.
The first position on the upper side in the drawing for communicating with each other as they are, and the discharge circuits 11 and 12 with the throttles 50a and 50b and the check valve 5.
It is a 2-port 2-position switching valve that can be switched to a second position on the lower side in the drawing, which is communicated with via 1, 52.

Merging / branching switching valve 14 of merging circuit 100C
a / b switching control circuit 200C including electromagnetic switching valves 15a, 15b, 15c and 15d is provided as switching means for the switching valves a and b and the throttle switching valves 55C and 56C. Fifteen
The diversion position is switched to the merging position by the pilot pressure sent from the hydraulic pilot pump 16 via a and 15b, and the throttle switching valves 55C and 56C are switched by the pilot pressure sent from the hydraulic pilot pump 16 via the electromagnetic switching valves 15c and 15d, respectively. The first position on the upper side in the drawing is switched to the second position on the lower side in the drawing, and the electromagnetic switching valve 1
The solenoids 5a, 15b and the solenoid operated directional control valves 15c, 15d are excited by the output current from the controller 17.

The pressure sensors 3 are respectively connected to the pilot lines 18 and 23 branched from the discharge circuits 11 and 12.
4, 35 are provided, the discharge pressures of the hydraulic pumps 1, 6 are respectively detected, and the signals from the pressure sensors 34, 35 are input to the controller 17.

Further, the load sensing circuits 27 and 28 are provided with pressure sensors 36 and 37, respectively, and the maximum load pressure of the hydraulic actuator groups 2 and 3 and the maximum load pressure of the hydraulic actuator groups 7 and 8 are detected respectively. The signals from the pressure sensors 36 and 37 are also input to the controller 17.

Further, tilt angle sensors 32 and 33 are provided for tilt detection of the hydraulic pump 1 and the hydraulic pump 6, respectively.
A rotation speed sensor 39 is attached to detect the rotation speed of the prime mover 38, and signals from the tilt angle sensors 32 and 33 and the rotation speed sensor 39 are also input to the controller 17.

The controller 17, as shown in FIG.
The pump discharge amount control calculation unit 17A and the combined / diversion switching control calculation unit 17B have respective functions, and the pump discharge amount control calculation unit 17A includes a load sensing control calculation unit 17a, a horsepower control calculation unit 17b, and a minimum value selection. It is composed of a part 17c. The load sensing control calculation unit 17a calculates a target pump displacement by load sensing control based on the pump discharge pressure, the maximum load pressure, and the pump displacement position, and the horsepower control calculation unit 17b calculates the pump discharge pressure and the pump displacement angle. The target pump displacement by horsepower control is calculated based on the prime mover rotation speed, and the minimum value selection unit 17c calculates the target pump displacement.
The smaller target pump displacement of 17b is selected. These calculations and processes are performed for each of the hydraulic pumps 1 and 6, and a signal corresponding to the target pump tilt angle selected by the minimum value selection unit 17c is output to the regulators 30 and 31.

FIG. 10 is a flowchart showing the processing contents of the merge / divide switching control calculation unit 17B of the controller 17.

In FIG. 10, the discharge flow rate is insufficient with respect to the required flow rate of the directional control valve groups 4 and 5 corresponding to the hydraulic pump 1 according to the calculation results of the load sensing control calculation unit 17a and the horsepower control calculation unit 17b. 1, it is determined that the hydraulic pump 6 is in the saturation state, and the hydraulic pump 6 corresponds to the directional switching valve group 9 according to the calculation results of the load sensing control calculation unit 17a and the horsepower control calculation unit 17b.
It is determined that there is a margin in the discharge flow rate with respect to the required flow rate of 10, that is, the hydraulic pump 6 is not in a saturation state, and the discharge pressure of the hydraulic pump 6 is higher than the discharge pressure of the hydraulic pump 1 by the signals from the pressure sensors 34 and 35. If it is also determined that the value is high, a signal for exciting the solenoids of the electromagnetic switching valves 15a and 15c is output (step 200 → 20).
1 → 202 → 203 → 204). As a result, the merge / divide switch valve 14a is switched to the merge position, and the throttle switch valve 5
5C is switched to the second position provided with the throttle 50a and the check valve 51, and supplies the discharge flow rate of the hydraulic pump 6 to the actuator on the hydraulic pump 1 side via the throttle 50a. Further, although the hydraulic pump 1 is in the saturation state and the hydraulic pump 6 is not in the saturation state, when the discharge pressure of the hydraulic pump 6 is not higher than the discharge pressure of the hydraulic pump 1, the solenoids of the electromagnetic switching valves 15a and 15b are turned on. Output an exciting signal (step 200 → 20)
1 → 202 → 203 → 205). As a result, the merge / divide switch valve 14a is switched to the merge position, and the merge / divide switch valve 14b is also switched to the merge position. At this time, since the load sensing circuit 27 and the load sensing circuit 28 communicate with each other, the hydraulic pumps 1 and 6 are both load-sensing-controlled by the maximum load pressure of all the actuator groups 2, 3, 7, and 8. The pressure oil supply of all the actuator groups 2, 3, 7 and 8 is covered by the total discharge flow rates of 1 and 6. Further, when the hydraulic pump 1 is in the saturation state but the hydraulic pump 6 is also in the saturation state, no signal for exciting the solenoid is output to any of the electromagnetic switching valves 15a to 15d (step 2).
00 → 201 → 202 → 211). As a result, the electromagnetic switching valves 15a to 15d are not excited and are kept in a shunt state.

Similarly, it is determined from the calculation results of the load sensing control calculation unit 17a and the horsepower control calculation unit 17b that the hydraulic pump 6 is in the saturation state, and it is determined that the hydraulic pump 1 is not in the saturation state. When it is determined from the signals from the sensors 34 and 35 that the discharge pressure of the hydraulic pump 1 is higher than the discharge pressure of the hydraulic pump 6, a signal for exciting the solenoids of the electromagnetic switching valves 15a and 15d is output (step 200 → 20).
1 → 206 → 208 → 209). As a result, the merge / divide switch valve 14a is switched to the merge position, and the throttle switch valve 5
6C is switched to the second position provided with the throttle 50b and the check valve 52, and supplies the discharge flow rate of the hydraulic pump 1 to the actuator on the hydraulic pump 6 side via the throttle 50b. Further, although the hydraulic pump 6 is in the saturation state and the hydraulic pump 1 is not in the saturation state, when the discharge pressure of the hydraulic pump 1 is not higher than the discharge pressure of the hydraulic pump 6, the solenoids of the electromagnetic switching valves 15a and 15b are turned on. Output an exciting signal (step 200 → 20)
1 → 206 → 208 → 210). As a result, the merge / divide switch valve 14a is switched to the merge position, and the merge / divide switch valve 14b is also switched to the merge position. At this time, since the load sensing circuit 27 and the load sensing circuit 28 communicate with each other, the hydraulic pumps 1 and 6 are both load-sensing-controlled by the maximum load pressure of all the actuator groups 2, 3, 7, and 8. The pressure oil supply of all the actuator groups 2, 3, 7 and 8 is covered by the total discharge flow rates of 1 and 6. Further, when neither the hydraulic pump 1 nor the hydraulic pump 6 is in the saturation state, the electromagnetic switching valve 15a
No signal for energizing the solenoid is output to any of .about.15d (step 200.fwdarw.201.fwdarw.206.fwdarw.21).
1). As a result, the electromagnetic switching valves 15a to 15d are not excited and are kept in a shunt state.

Here, whether the hydraulic pump 1 or 6 is in the saturation state is determined by, for example, the target pump displacement calculated by the load sensing control calculation unit 17a and the target pump displacement calculated by the horsepower control calculation unit 17b. It can be judged by comparing. That is, if the target pump displacement of the load sensing control is smaller than the target pump displacement of the horsepower control, it can be considered that the state is not in the saturation state, and if the target pump displacement is in the saturation state, the state is in the saturation state.

The above-mentioned combination / diversion switching control calculation unit 1
In the processing flow of 7B, whether or not the hydraulic pump 1 or 6 cannot supply the required flow rate of the corresponding directional control valve group is determined by whether or not the hydraulic pump 1 or 6 is in the saturation state. It may be determined whether or not the hydraulic pump 1 or 6 has reached the maximum tilt position as in the above embodiment. The processing flow in this case is shown in FIG. 2 in the figure
01A and 206A are processing procedures for determining whether or not the hydraulic pump 1 or 6 has reached the maximum tilt position, and this can be performed by signals from the tilt angle sensors 32 and 33. In this case, the processing procedure 207 for checking whether the hydraulic pump 1 is in the saturation state is 206A.
Will be added between the procedure No. and the procedure No. 208.

The same effect as that of the first or second embodiment can be obtained by the present embodiment having the above-described configuration. Further, in the present embodiment, since the load sensing control, the horsepower limitation control and the switching control of the merging / shunting switching valve are all electrically controlled, the saturation state of each hydraulic pump can be easily detected, and the detection result thereof can be easily obtained. Thus, the switching control of the merging / branching switching valve can be stably performed.

Further, since it is detected by comparing the target pump tilt of the load sensing control and the target pump tilt of the horsepower control whether or not the hydraulic pump is in the saturation state, the hydraulic pump on the merge supply side is actually in the saturation state. Before, the merging / branching switching valve 14a or 14b can be switched to the diverting position, and a stable merging / branching action can be obtained.

In the above embodiment, whether the discharge pressure of the hydraulic pump 1 or the discharge pressure of the hydraulic pump 6 is higher is determined by comparing the pressures of those discharge circuits. The maximum load pressure may be compared with the maximum load pressure of the actuator group on the hydraulic pump 6 side, and the same effect can be obtained in this case as well.

Further, the load sensing control, the horsepower limiting control, and the switching control of the merging / shunting switching valve are not limited to hydraulic pressure only or electricity only, and a combination of hydraulic pressure and electricity is also possible.

[0097]

As described above, according to the present invention, since the flow is merged through the throttle at the merge position, the discharge flow rate of the hydraulic pump on the merge supply side is not entirely supplied to the merged side. The pressure oil is surely supplied to the actuator group on the supply side, and the pressure oil can be appropriately supplied to all the actuators that need to be operated, so that the work speed can be increased.

Further, since there is a diaphragm, the first and second
The independence of the load sensing control of the hydraulic pump can be maintained, and the pump discharge amount on the side having a reserve when the first and second hydraulic pumps are subjected to horsepower control can be utilized to the maximum extent.

[Brief description of drawings]

FIG. 1 is a diagram showing a hydraulic control circuit of a hydraulic drive system by load sensing control according to a first embodiment of the present invention.

FIG. 2 is a diagram showing, as a comparative example, a merging / dividing system of a plurality of hydraulic pumps in a hydraulic drive system according to a conventional load sensing control.

3 is a diagram showing a flow rate characteristic of the hydraulic pump in FIG.

FIG. 4 is a diagram showing a flow rate characteristic of a hydraulic pump according to the present invention.

FIG. 5 is a diagram showing flow rate characteristics of the hydraulic pump according to the present invention.

FIG. 6 is a diagram showing a hydraulic control circuit of a hydraulic drive system by load sensing control according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a hydraulic control circuit of a hydraulic drive system by load sensing control according to a third embodiment of the present invention.

FIG. 8 is a diagram showing a hydraulic control circuit of a hydraulic drive system by load sensing control according to a fourth embodiment of the present invention.

9 is a functional block diagram showing a control function of a controller 17 shown in FIG.

FIG. 10 is a diagram illustrating a merge / shunt switching control calculation unit 17 shown in FIG. 9;
It is a flowchart which shows an example of the processing content of B.

11 is a combined / diversion switching control calculation unit 17 shown in FIG.
13 is a flowchart illustrating another example of the processing content of B.

FIG. 12 is a diagram showing a combining / splitting system of a plurality of hydraulic pumps in a conventional hydraulic drive system by load sensing control.

[Explanation of symbols]

1,6 Variable displacement hydraulic pump 2,3,7,8 Hydraulic actuator 4,5,9,10 Directional switching valve 11,12 Discharge circuit 13; 13a; 13b Converging line 14 ;; 14A; 14B, 14C; 14a , 14b Combined / diversion switching valves 15a to 15d Electromagnetic switching valve 16 Hydraulic pilot pump 17 Controller 17A Pump discharge amount control calculation unit 17B Combined / diversion switching control calculation unit 17a Load sensing control calculation unit 17b Horsepower control calculation unit 17c Selection unit 18, 23 Pilot line 27, 28 Load sensing circuit 20, 24 LS control valve 29, 42 Servo mechanism 30, 31 Regulator 32, 33 Tilt angle sensor 34, 35, 36, 37 Pressure sensor 38 Engine 39 Rotation speed sensor 43, 44, 45,46; 47,48 Pressure control valve 50; 5 a, 50b Throttle 51, 52 Check valve 55, 56; Throttle switching valve 60 Circuit pressure comparison detection valve 61, 62 Maximum tilt detection valve 63, 64 Load sensing differential pressure detection valve 65, 66 Spring 100, 100A, 100B, 100C Junction circuit 200; 200A; 200B; 200C Junction / diversion switching control circuit

Claims (7)

[Claims] 1. A first and a second variable displacement hydraulic pump,
First and second hydraulic actuator groups respectively driven by the pressure oil discharged from the first and second hydraulic pumps, and first and second hydraulic pumps from the first and second hydraulic pumps.
First and second directional control valve groups for controlling the flow of pressure oil supplied to the hydraulic actuator group, a first load sensing circuit for detecting a maximum load pressure of the first hydraulic actuator group, and A second load sensing circuit that detects the maximum load pressure of the second hydraulic actuator group, and a first load sensing circuit that detects the first load sensing circuit.
Discharge amount control means for controlling the discharge amount of the first hydraulic pump so that the pump discharge pressure is higher than the maximum load pressure of the actuator group, and the second load sensing circuit detects the second discharge amount. Of the second hydraulic pressure actuator group so that the pump discharge pressure becomes higher than the maximum load pressure of the hydraulic actuator group.
In a hydraulic drive device by load sensing control, comprising: a second discharge amount control means for controlling the discharge amount of the second hydraulic pump, a discharge circuit of the first hydraulic pump and a discharge circuit of the second hydraulic pump. Between the first load sensing circuit and the second load sensing circuit, and a shunt position for blocking both discharge circuits and both load sensing circuits, and both discharge circuits via a throttle. A merging circuit that is switchable between a first merging position that is in communication and that blocks both load sensing circuits and a second merging position that is in communication between both discharge circuits and that communicates both load sensing circuits; Of the two hydraulic pumps, one hydraulic pump is in a state where it cannot supply the required flow rate of the corresponding actuator group, and the discharge pressure of the other hydraulic pump is When higher than the discharge pressure of the pressure pump is switched the coupling circuit to the first joining position, in a state where the one of the hydraulic pump is not completely same supply required flow rate,
And a merging / dividing switching control means for switching the merging circuit to the second merging position when the discharge pressure of the one hydraulic pump is higher than the discharge pressure of the other hydraulic pump. Hydraulic drive system with sensing control. 2. The merging circuit, a first merging line connecting the discharge circuit of the first hydraulic pump and the discharge circuit of the second hydraulic pump, the first load sensing circuit, and the second Second merging line for connecting to the load sensing circuit of No. 1 and a single merging line disposed on the first and second merging lines and switchable between the diverging position, the first merging position and the second merging position. The hydraulic drive system according to claim 1, further comprising a merging / branching switching valve. 3. The merging circuit is arranged in two merging lines connecting the discharge circuit of the first hydraulic pump and the discharge circuit of the second hydraulic pump, and the two merging lines, and the diverging position Both of the two merging lines are shut off when switched to the first merging line, and one of the two merging lines is connected to the other merging line when the first merging line is switched to the first merging line. Is connected to the other merging line when the second merging position is switched to the second merging position and the one merging line is cut off, and the merging / branching switching valve is arranged on each of the two merging lines. 2. The hydraulic drive system according to claim 1, further comprising: a check valve that allows only the flow of pressure oil from the other hydraulic pump to one hydraulic pump. 4. The first maximum displacement detecting means for detecting whether or not the first hydraulic pump has reached a maximum displacement position, and the second hydraulic pump, Second maximum tilt detection means for detecting whether or not the maximum tilt position has been reached, and these detection means detect that the first or second hydraulic pump has reached the maximum tilt position. The load sensing control according to claim 1, wherein it is determined that one of the first and second hydraulic pumps cannot supply the required flow rate of the corresponding actuator group. Hydraulic drive. 5. The first saturation detection means for detecting whether the first hydraulic pump is in a saturation state in which the discharge flow rate is insufficient with respect to the required flow rate of the corresponding directional control valve. Means and second saturation detection means for detecting whether or not the second hydraulic pump is in a saturation state in which the discharge flow rate is insufficient with respect to the required flow rate of the corresponding directional control valve, and the detection means detects the first and second saturation values. When it is detected that the first or second hydraulic pump is in the saturation state, one of the first and second hydraulic pumps is in a state where it cannot supply the required flow rate of the corresponding actuator group. The hydraulic drive device according to claim 1, wherein: 6. The first saturation detection for detecting whether the first hydraulic pump is in a saturation state in which the discharge flow rate is insufficient with respect to the required flow rate of the corresponding directional control valve. Means and second saturation detection means for detecting whether or not the second hydraulic pump is in a saturation state in which the discharge flow rate is insufficient with respect to the required flow rate of the corresponding directional control valve, and the first and second One of the hydraulic pumps is unable to supply the required flow rate of the corresponding directional control valve group, and the discharge pressure of the other hydraulic pump is higher than the discharge pressure of the one hydraulic pump. In addition, when it is further detected by the first and second saturation detecting means that the other hydraulic pump is not in the saturation state. The merging circuit is switched to the first merging position, the one hydraulic pump is also in a state of being unable to supply the required flow rate, and the discharge pressure of the one hydraulic pump is higher than the discharge pressure of the other hydraulic pump. In addition to being high, the merging circuit is switched to the second merging position when it is detected that the other hydraulic pump is not in a saturation state.
A hydraulic drive device according to the described load sensing control. 7. The load sensing means for calculating the first target pump displacement by load sensing control based on the pump discharge pressure, the maximum load pressure, and the pump displacement position, respectively. Control calculation means, horsepower control calculation means for calculating a second target pump displacement by horsepower control based on the pump discharge pressure, pump displacement angle, and prime mover speed, and the first and second target pump displacements. And a means for controlling the corresponding hydraulic pump by selecting the smaller one of the first target pump tilt and the second target pump tilt comparing the first target pump tilt and the second target pump tilt. The hydraulic drive system according to claim 5 or 6, wherein whether the hydraulic pump is in a saturation state or not is detected by comparing both target pump displacements.