JP2003148412A - Hydraulic control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a hydraulic control system with a small confluent circuit. SOLUTION: This hydraulic control system includes a plurality of hydraulic driving systems 10, 20 for performing flow control and pressure control to variable displacement pumps 12, 22 for hydraulically driving load 14, 24, the confluent circuit 50 provided extending between the pump discharge lines 13, 23 of both systems, and a switching control means 44 for performing switching between confluence and non-confluence and also switching between the subsidiary state and the independent state concerning about the control of the hydraulic driving systems 10, 20. The confluent circuit 50 is provided with seat valves 52, 62 interposed in confluent lines 51, 61 communicating the pump discharge lines 13, 23 with each other and pilot circuits 53+54, 63+64 for supplying pilot pressure to the above valves to selectively switch its operating state to the shut-off state or the check valve state. The direction switching and non-return functions are made intensive in the seat valves and the direction switching valve is deviated from the confluence line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control system used for driving an industrial machine such as an injection molding machine,
More specifically, the present invention relates to a hydraulic pressure control system that includes a plurality of variable displacement hydraulic pumps and that can control the pressure and flow rate of the hydraulic liquid that is discharged from these pumps and merges.

[0002]

2. Description of the Related Art In order to reduce the cost of an industrial machine, a hydraulic control system that dynamically combines a plurality of small or medium-sized hydraulic pumps incorporated therein to secure a required supply flow rate, And pressure can be controlled freely (Japanese Patent Laid-Open No. 2000-
No. 274406). This system (see FIG. 5) includes a plurality of hydraulic drive systems 10 and 20, and a merging circuit 30.
And a switching control unit 34 (switching control means). In the drawing (FIGS. 5 and 6), the hydraulic main line is shown by a thin solid line, the pilot line is shown by a thin long broken line, and the electric signal line is shown by a thin two-dot chain line.

The hydraulic drive system 10 (see FIG. 5) electronically drives the load and controls the flow rate and the pressure when driving the load.
And a pump discharge line 13 and an actuator 14. The hydraulic drive system 20 also includes an electronic circuit 21, a pump unit 22, a pump discharge line 23, and an actuator 24 in order to hydraulically drive another load in the independent state.

The actuator 14 is a hydraulic cylinder or a hydraulic motor connected to a load, and the pump discharge line 1
3 is a flow path extending from the discharge port of the pump unit 12 to reach the port of the actuator 14. The pump unit 12 (see FIG. 6) is mainly a variable displacement hydraulic pump that is rotationally driven by an electric motor or the like not shown. It is the one. The pump unit 12 has means for varying the capacity of the pump in accordance with the received capacity command R1, means for detecting the discharge pressure P1 and converting it into an electric signal and outputting the pressure detection value Pf1, and detecting the pump capacity. Means for converting the flow rate detection value Qf1 into an electric signal and outputting it as a physical quantity corresponding to the discharge flow rate Q1 are additionally provided.

The electronic circuit 11 (see FIG. 5) receives the pressure command Ps1 and the flow rate command Qs1 from the pump unit 1.
2 is a control circuit for performing flow rate control and pressure control for the flow rate control Ps1 and the flow rate command Qs1 based on the mutual relationship between the pressure command Ps1 and the flow rate command Qs1 and other commands not shown, the operating state of the pump or load, Either is valid. And
At the time of flow rate control, the capacity command R1 that causes the flow rate detection value Qf1 to follow the flow rate command Qs1 is generated, while at the time of pressure control,
Capacity command R1 that causes pressure command Ps1 to follow pressure command Ps1
Is generated and the capacity command R1 is sent to the pump unit 12.

The electronic circuit 21 is also a similar control circuit,
A volume command R2 that causes the flow rate detection value Qf2 to follow the flow rate command Qs2 is generated during flow rate control, while a volume command R2 that causes the pressure command Ps2 to follow the pressure command Ps2 is generated during pressure control, and the volume command R2 is generated. It is designed to be sent to 22. However, the pressure detection value Pf2 is not directly received from the pump unit 22, but is changed over to the switching control unit 3
It is supposed to be received via the 4.

The switching control section 34 is an electronic circuit for switching between a dependent state and an independent state relating to the control of the drive systems 10 and 20 in accordance with a switching command S1 received from a higher-order controller (mother machine) not shown. In the independent state, the pressure command Ps1 and the flow rate command Qs1 received from the host controller are transferred to the electronic circuit 11, and the pressure command Ps2 and the flow rate command Qs2 received from the host controller or from another setting device are sent to the electronic circuit 21. By transferring the pressure detection value Pf2 received from the pump unit 22 to the electronic circuit 21, the drive system 1
0 and 20 are independently operated.

In the dependent state, the pressure command Ps1 and the flow rate command Qs1 are transferred to the electronic circuit 11, while the pressure command Ps1 is transmitted.
Stop the transfer of s2, flow rate command Qs2, and pressure detection value Pf2,
A pressure command having a value slightly lower than the pressure command Ps1 is generated, and this, the flow rate command Qs1 and the pressure detection value Pf1 are combined with each other to obtain the pressure command Ps2.
The flow rate command Qs2 and the pressure detection value Pf2 are sent to the electronic circuit 21 in place of the flow rate command Qs2 and the pressure detection value Pf2 so that the drive systems 10 and 20 are operated in cooperation with each other, and the hydraulic drive system 20 is subordinate to the hydraulic drive system 10 during the cooperation. It is designed to let you.

The merging circuit 30 also switches merging / non-merging in accordance with the switching command S1. Therefore, in the merging circuit 30, one end of the merging circuit 30 is connected to the pump discharge line 13 and the other end thereof reaches the pump discharge line 23. And a check valve 32 which is provided through the flow path 31 to flow the pressure oil from the pump discharge line 23 to the pump discharge line 13 but not from the pump discharge line 13 to the pump discharge line 23, and the pump discharge line 23. And a directional switching valve 33 that is inserted in the flow path 31 and interrupts the communication between the flow path 31 and the flow path 31 in response to the switching command S1.

When the switching command S1 indicates a non-merging state, the directional switching valve 33 cuts off the communication between the flow path 31 and the pump discharge line 23, and the pump discharge lines 13 and 23 are separated from each other. The hydraulic drive systems 10 and 20 can operate individually. At that time, in the hydraulic drive system 10,
The actuator 14 is hydraulically driven by the pump unit 12, and a flow rate control and a pressure control for the pump unit 12 are performed by the electronic circuit 11, and a discharge flow rate Q1 supplied in the pump discharge line 13 is provided.
The discharge pressure P1 follows the flow rate command Qs1 or the pressure command Ps1. In the hydraulic drive system 20, the discharge flow rate Q2 or the discharge pressure P2 supplied from the pump unit 22 to the actuator 24 in the pump discharge line 23 depends on the flow rate command Qs2 or the pressure command according to the flow rate control and the pressure control by the electronic circuit 21. Follow Ps2.

On the other hand, when the switching command S1 indicates merging, the flow passage 31 and the pump discharge line 23 are made to communicate with each other by the directional switching valve 33, and the pump discharge lines 13 and 23 are connected to the check valve 32. The hydraulic drive systems 10 and 20 can operate in cooperation with each other by communicating with each other. At that time, in the hydraulic pressure drive system 10, the discharge flow rate Q1 or the discharge pressure P1 follows the flow rate command Qs1 or the pressure command Ps1 as in the independent state, but in the hydraulic pressure drive system 20, the discharge flow rate Q2 and the discharge pressure P.
2 is not the flow rate command Qs2 or the pressure command Ps2 but the flow rate command Qs1
Or follow the pressure command Ps1. Moreover, the discharge flow rate Q2
Pressure oil flows from the pump discharge line 23 into the pump discharge line 13 via the merging circuit 30.

Thus, the plurality of pump units 12, 2
The pressure oil discharged from 2 joins, and the large amount of pressure oil obtained thereby drives the actuator 14 at high speed. Further, by introducing the switching control unit 34 together with the merging circuit 30 as described above, in addition to the cost reduction, the cutoff characteristic at the time of shifting from the flow rate control to the pressure control is also improved.

[0013]

The merging circuit 30 described above merges the discharge liquid of the pump unit 22 with the discharge liquid of the pump unit 12, and supplies the combined flow rate to the hydraulic drive system 10 side. This can be done only toward the actuator 14 of. On the other hand, both actuators 1
It would be convenient if the combined flow rate could be supplied to both 4 and 24. If a merge operation (cooperative operation) and a non-merge operation (independent operation) can be performed for any load, further speedup of the machine (mother machine) can be realized without using an expensive large pump. For that purpose, it is conceivable to duplicate the merging circuit 30.

However, in the conventional hydraulic control system,
The merging circuit that uses multiple variable displacement hydraulic pumps incorporates not only a directional valve but also a check valve. At the time of pressure control, the control of each pump affects each other, which causes an oscillation state in the overall control, and the pump flow caused by the backflow from the high-pressure side pump to the low-pressure side pump due to the difference in control pressure. This is because it is necessary to prevent damage. Therefore, if the merging circuit is doubled, both the direction switching valve and the check valve are doubled.

Specifically (see FIG. 7), the duplexed merging circuit 40 not only switches the merging / non-merging from the hydraulic drive system 20 to the hydraulic drive system 10 in accordance with the switching command S1, but also in the opposite direction. The flow changes. That is, the merging / non-merging from the hydraulic pressure drive system 10 to the hydraulic pressure drive system 20 is switched according to the switching command S2. Therefore, the merging circuit 40 is added to the merging circuit 30 and one end thereof is connected to the pump discharge line 23. Flow path 41 connected to the pump discharge line 13 and the other end reaching the pump discharge line 13, and pressure oil provided through the flow path 41 from the pump discharge line 13 to the pump discharge line 2
3 and the check valve 42 that does not flow from the pump discharge line 23 to the pump discharge line 13 and the pump discharge line 1
There is also provided a directional switching valve 43 which is interposed in the valve 3 and which cuts off the communication between it and the flow channel 41 in response to the switching command S2.

With the expansion, the switching control unit 34 is also expanded to become the switching control unit 44. It receives a switching command S2 in addition to the switching command S1 from the host controller, and also mediates the return of the pressure detection value Pf1 from the pump unit 12 to the electronic circuit 11. The switching command S1 is the same as the conventional one, but the switching command S2 is modified as follows. That is, in the independent state, the pressure command Ps1, the flow rate command Qs1, and the pressure detection value Pf1 are transferred to the electronic circuit 11,
The pressure command Ps2, the flow rate command Qs2, and the pressure detection value Pf2 are transferred to the electronic circuit 21, and the drive systems 10 and 20 are separately operated independently. On the other hand, when the switching command S2 becomes significant, for example, when it is turned on, the transfer of the pressure command Ps1, the flow rate command Qs1, and the pressure detection value Pf1 is stopped, and a pressure command of a value slightly lower than the pressure command Ps2 is generated. And the flow rate command Qs2 and the pressure detection value Pf2 are sent to the electronic circuit 11 instead of the pressure command Ps1, the flow rate command Qs1 and the pressure detection value Pf1, so that the hydraulic drive system 10 is transferred to the hydraulic drive system 20. It is designed to be subordinate.

Thus, the check valve 32 and the direction switching valve 3
In addition to 3, the number of check valves 42 and direction switching valves 43 in which the free flow is opposite can be increased to realize a merging circuit in which the merging direction can be selected, but any of the valves 32, 33, 42, 4
Also for No. 3, a large size is required so that the pump flow rate can be passed. Therefore, if the bidirectional merging circuit is configured by the above-mentioned simple duplication method, not only the size of the circuit block becomes large, but also the cost increases.

Therefore, in order to perform flow rate control and pressure control for a plurality of variable displacement hydraulic pumps without any inconvenience even at the time of merging, it is assumed that a check valve or a substitute thereof is incorporated in the merging circuit so that the merging is bidirectional. In order to achieve the above, or even if the merging is performed in only one direction, it is a technical subject to devise the structure of the merging circuit so that the merging circuit is small and inexpensive. The present invention has been made to solve such a problem, and an object thereof is to realize a hydraulic control system having a small confluence circuit.

[0019]

With respect to the first to third solving means invented to solve the above problems,
The configuration and action and effect will be described below. In any case, in order to satisfy the prerequisite conditions, a plurality of hydraulic drive systems that perform flow rate control and pressure control for a variable displacement pump that hydraulically drives a load, and a confluence provided across both pump discharge lines. In a hydraulic control system including a circuit, a confluence circuit is devised.

[First Solving Means] In the hydraulic control system of the first solving means, as described in claim 1 at the beginning of the application, the merging circuit causes the first merging line to communicate the pump discharge lines with each other. And a second merging line, a first seat valve inserted in the first merging line, and a first pilot that supplies pilot pressure to the first merging line to selectively set its operating state to a closed state or a check valve state. A circuit, a second seat valve inserted in the second merging line, and a pilot pressure supplied to the second seat valve to selectively close its operation state or a check valve in the opposite direction to the first seat valve. And a second pilot circuit to bring it into a state. Alternatively, as described in claim 3 at the beginning of the application, a seat valve in which the merging circuit is inserted in the merging line for communicating the pump discharge lines with each other, and a pilot pressure is supplied to the seat valve to select an operating state thereof. It is equipped with a pilot circuit that is normally closed or a check valve state.

In the hydraulic control system of the first solving means as described above, the seat valve is inserted in the merging line, and the seat valve is in the check valve state at the merging time.
Similar to the conventional circuit that incorporates a check valve, the control state is stable even when merging. At the time of non-merging, the seat valve closes the merging line and the communication between the pump discharge lines is cut off. And
Whether the seat valve is in the merged state or the non-merged state depends on the pilot pressure generated by the pilot circuit.

As a result, the functions of both the direction switching and the check of the pump discharge flow rate are integrated into the seat valve to be embodied. Only the seat valve is directly inserted into the merging line, and the large-sized directional control valve, which was conventionally inserted in the merging line and the pump discharge line, is removed from the merging circuit to provide a small pilot circuit. Since it is replaced by, the merging circuit becomes smaller by that amount.

In particular, when the merging circuit is duplicated, the first merging line, the first seat valve, and the first pilot circuit fulfill a unidirectional merging function, and the second merging line and the second merging line are combined.
The seat valve and the second pilot circuit fulfill the function of merging in the opposite directions, but in both cases, the large-sized directional switching valve is replaced by the small pilot circuit, so that the miniaturization greatly advances. Therefore, according to the present invention, it is possible to realize a hydraulic control system having a small merging circuit. Further, it is possible to realize a small-sized hydraulic control system capable of bidirectional merging.

[Second Solving Means] The hydraulic pressure control system of the second solving means is, as described in claim 2 at the beginning of the application, the hydraulic pressure shown in the first half of the first solving means. In the control system, one or both of the first pilot circuit and the second pilot circuit are attached to a corresponding seat valve, that is, a seat valve to be pilot-operated so as to generate pilot pressure from both port pressures thereof. It has become. Alternatively, as described in claim 4 at the beginning of the application, in the hydraulic control system shown in the latter half of the first solution means, the pilot circuit is mounted on the seat valve, and both of them are provided. The pilot pressure is generated from the port pressure.

In the fluid pressure control system of the second means as described above, since the pilot circuit is mounted on the seat valve, if the seat valve can be installed at a suitable place,
Since it is not necessary to occupy the installation place in the pilot circuit, miniaturization will be further advanced. Moreover, even in such a case, the pilot pressure is generated from both port pressures of the seat valve, which may complicate the pilot circuit or lead the piping from the pilot circuit to the outside. There is no.

Thus, not only can the pilot circuit be attached to the seat valve to promote miniaturization, but it can be easily performed by local modification. Therefore, according to the present invention, it is possible to easily realize a hydraulic control system having a small merging circuit.

[Third Solving Means] In the hydraulic control system of the third solving means, as described in claim 5 at the beginning of the application, the merging circuit interposes on a merging line for communicating the pump discharge lines with each other. A seat valve that is provided by inserting and selects either one of the both port pressures from the merging line to lead to the pilot pressure, and is in a check valve state, and switches the flow direction according to the selection of the port at that time, The seat valve is mounted to generate pilot pressure from both port pressures and supplies the pilot pressure to the seat valve to selectively switch its operating state to a closed state or a check valve state and reverse the operating state of the seat valve. A pilot circuit that selects either one of the two port pressures of the seat valve when the pilot pressure is generated when the valve is stopped is provided.

In the fluid pressure control system of the third solving means as described above, since the seat valve is in the check valve state in any direction according to the pilot pressure, the seat valve inserted in the merging line. Even with just one, bidirectional merging can be selected. As a result, the functions of the double check valve are integrated and integrated into a single seat valve, which further reduces the size. Therefore, according to the present invention, a hydraulic control system capable of bidirectional merging can be realized in a smaller size and easily.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION A specific mode for carrying out the hydraulic control system of the present invention achieved by the above-mentioned means will be described with reference to the following first to fourth examples. The first embodiment shown in FIG. 1 has a double structure among the above-mentioned first solving means (the portion described in the first claim).
The second embodiment shown in FIG. 2 is
Of the above-mentioned second solving means, the one having a double structure (the portion described in claim 2 at the beginning) is embodied, and the third embodiment shown in FIG. 3 is the same as the above-mentioned first solving means. The fourth embodiment shown in FIG. 4 embodies a single structure (the part described in the first claim), and the fourth embodiment shown in FIG. 4 has the single structure (the first claim). 4)) and the third solution means (original claim 5).

In the drawings, for simplification, the hydraulic main line is shown by a thin solid line, the pilot line is shown by a thin long broken line, and the electric signal line is shown by a thin two-dot chain line. In addition, in the drawings, the same components as those in the conventional art are denoted by the same reference numerals, and therefore the duplicated description will be omitted, and hereinafter, the difference from the conventional art will be mainly described.

[0031]

First Embodiment The configuration of a hydraulic control system embodying the hydraulic control system of the present invention will be described with reference to the circuit diagram of FIG.

This system differs from the conventional example (FIGS. 5 and 6) and the prediction example (FIG. 7) in that the merging circuit 30 and the merging circuit 40 are replaced by a merging circuit 50. Confluence circuit 50
In response to the fact that now supports bidirectional merging, the switching control unit 44 of the expected example is adopted for the switching control,
When the merging / non-merging switching is performed, the subordinate state / independent state relating to the control of the hydraulic drive system is also switched. The hydraulic drive systems 10 and 20 are the same as conventional ones.

In the merging circuit 50, a first merging line 51, a first seat valve 52, a shuttle valve 53, and a direction switching are provided to enable merging from the hydraulic pressure drive system 20 to the hydraulic pressure drive system 10. A first pilot circuit consisting of valve 54 is provided. The first merging line 51 is the pump discharge line 1
3, 23, and 23. The flow paths are made of pipes having the same thickness as 3, 23, and have one end connected to the pump discharge line 13 and the other end connected to the pump discharge line 23. Seat valve 52
Employs a pilot operated check valve of the same size as the check valve 32, which allows free flow to the pump discharge line 23.
It is inserted in the first merging line 51 in such a direction as to go to the pump discharge line 13.

The shuttle valve 53 is a small-sized three-port valve, and the pilot pressure is supplied from the upstream port A and the downstream port B of the seat valve 52 immediately or through the first merging line 51 communicating with the upstream port A and the pilot pressure in a narrow pilot line. Leading
The higher pressure of the two is made the pilot pressure, and this is also fed to the seat valve 52 through a thin pilot line. The direction switching valve 54 is inserted into a line connected to the upstream side port A of the seat valve 52 among those pilot lines, and opens and closes the pilot line according to the switching command S1. .
This is smaller than the conventional directional control valve 33.
With such a shuttle valve 53 and a direction switching valve 54,
The first pilot circuit generates a pilot pressure from the pressures of both ports A and B of the seat valve 52 and supplies the pilot pressure to the seat valve 52 to selectively set its operating state to a closed state or a check valve state. Will be things.

In addition, in the merging circuit 50, a second merging line 61, a second seat valve 62, and a second merging line 61 are provided in order to enable merging from the hydraulic driving system 10 in the opposite direction to the hydraulic driving system 20. A second pilot circuit including a shuttle valve 63 and a direction switching valve 64 is also provided. The second merging line 61 is also the first
Like the confluence line 51, the pump discharge lines 13, 23
It is intended to communicate with each other. The seat valve 62 is a pilot operated check valve similar to the seat valve 52, but when the seat valve 62 is inserted into the second merging line 61, the seat valve 62 is connected in the opposite direction so that a free flow is generated from the pump discharge line 13 to the pump discharge line 2.
It is going to go to 3.

The shuttle valve 63 is also a small valve similar to the shuttle valve 53. Similarly, pilot pressure is generated from the upstream side port A and the downstream side port B of the seat valve 62, and the higher pressure is applied to the seat valve. It is designed to be sent to 62. The directional control valve 64, like the directional control valve 54, is small in size,
Similarly, the upstream port A of the seat valve 62 and the shuttle valve 63
Is inserted to the pilot line connecting the B port of
The opening / closing is performed according to the switching command S2. With such a shuttle valve 63 and the direction switching valve 64, the second
The pilot circuit consists of both ports A and B of the relevant seat valve 62.
From the pressure of the seat valve 62
To the closed state or the check valve state.

The mode of use and operation of the hydraulic control system of the first embodiment will be described.

In this system as well, the switching commands S1 and S2 and the pressure command P are sent from a host controller (mother machine) not shown.
When s1 and Ps2 and the flow rate commands Qs1 and Qs2 are received and the switching commands S1 and S2 both indicate non-merging, for example, when the switch is in the off state, the operating state becomes the independent state. In this state, the direction switching valve 54 is in the open state, the pressures of both ports A and B of the seat valve 52 are both guided to the shuttle valve 53, and the higher pressure becomes the pilot pressure of the seat valve 52.
The seat valve 52 remains closed. Similarly, the seat valve 62 also maintains the closed state.

Therefore, the first merging line 51 and the second merging line 61 are both closed, and the pump discharge line 1
Since the liquids 3 and 23 are separated, the hydraulic drive system 10
Operates independently according to the pressure command Ps1 and flow rate command Qs1,
The hydraulic drive system 20 operates independently according to the pressure command Ps2 and the flow rate command Qs2. In such a single operation state, neither of the hydraulic drive systems 10 and 20 is affected by the control state of the other, so that the flow rate control and the pressure control are appropriately performed.

Next, when the switching command S1 indicates merging, for example, in the ON state, the directional switching valve 54 operates to disconnect the pilot line from the first merging line 51, and at the same time, the shuttle valve. The corresponding port pressure of 53 is dropped to the tank pressure. Then, shuttle valve 5
Since the pilot pressure supplied from 3 to the seat valve 52 is set to the pressure of the downstream side port B of the seat valve 52, the seat valve 52 enters the check valve state and the pump discharge line 23
From the first discharge line 1 through the first merging line 51
The flow towards 3 flows freely, while the reverse flow is blocked. Therefore, the discharge flow rate Q2 of the pump unit 22 merges with the discharge flow rate Q1 of the pump unit 12 on the assumption that the switching command S2 remains instructing non-merging.

In such a merged state, the hydraulic drive system 20 is operated in the same manner as the system of FIGS. 5 and 7 already described.
Operate in cooperation with each other in a manner dependent on the hydraulic drive system 10. Specifically, in the hydraulic drive system 10, the discharge flow rate Q1 or the discharge pressure P1 follows the flow rate command Qs1 or the pressure command Ps1,
Even in the hydraulic drive system 20, the discharge flow rate Q2 or the discharge pressure P2 is
The flow rate command Qs1 or the pressure command Ps1 is followed, and the discharge flow rates Q1 and Q2 of both are merged in the pump discharge line 13. Thus, also in this case, the pressure oil discharged from the plurality of pump units 12, 22 merges, and the actuator 14 is driven at high speed by the large flow rate of pressure oil obtained thereby. Moreover, at that time, the seat valve 52 functions as a check valve, so that the cut-off characteristic at the time of shifting from the flow rate control to the pressure control is not impaired.

Further, when the switching command S2 instructs the merging, the directional switching valve 64 is actuated, the pilot line there is disconnected from the second merging line 61, and at the same time, the corresponding port pressure of the shuttle valve 63 is changed. Dropped to tank pressure. Then, the pilot pressure supplied from the shuttle valve 63 to the seat valve 62 is set to the pressure of the downstream side port B of the seat valve 62, so that the seat valve 62 is in the check valve state and is discharged from the pump discharge line 13. The flow that exits and flows toward the pump discharge line 23 via the second merging line 61 freely flows, while the reverse flow is blocked. for that reason,
The discharge flow rate Q1 of the pump unit 12 merges with the discharge flow rate Q2 of the pump unit 22 on the assumption that the switching command S1 remains instructing non-merging.

In such a merged state, the hydraulic drive system 10 and the hydraulic drive system 20 cooperate with each other in the same manner as the system of FIG. 7 described above. Specifically, in the hydraulic drive system 10, the discharge flow rate Q1 or the discharge pressure P1 follows the flow rate command Qs2 or the pressure command Ps2, and in the hydraulic drive system 20, the discharge flow rate Q2 or the discharge pressure P2 is the flow rate command Qs2. Or follow the pressure command Ps2, and discharge flow rate Q1, Q of both
2 meet at the pump discharge line 23. Thus, also in this case, the pressure oil discharged from the plurality of pump units 12 and 22 merges, and the actuator 24 is driven at high speed by the large amount of pressure oil obtained thereby. Moreover, at that time, the seat valve 62 functions as a check valve, so that the cut-off characteristic at the time of shifting from the flow rate control to the pressure control is not impaired.

As described above, in the fluid pressure control system of this example, the merging circuit is constituted by the combination of the pilot operated check valve and the pilot circuit, and by arranging it in duplicate, Even a hydraulic control system capable of two-way merging has been realized compactly. Moreover, the required control characteristics are maintained.

[0045]

[Second Embodiment] The hydraulic control system of the present invention, whose circuit diagram is shown in FIG. 2, is different from that of the first embodiment described above.
The seat valves 52 and 62 are so-called cartridge valves. The cartridge valve is also called a logic valve, and the A port pressure receiving surface and the B port pressure receiving surface face the pilot pressure receiving surface, and the sum of the A port pressure receiving area and the B port pressure receiving area is equal to the pilot pressure receiving area. Is. When either one of the pressures of both ports A and B is selected and led to the pilot pressure, the check valve state is established and the direction of free flow and the direction of blocking are switched according to the selection of the port at that time. It is like this. Also,
It is also possible to stack and install pilot circuits on a cover that covers the pilot pressure receiving surface.

Specifically, the A and B ports of the cartridge valve used for the seat valve 52 are connected to the first merging line 51, and the shuttle valve 53 and the direction switching valve 54 are connected.
Is placed over the cover. Also, the seat valve 62
The A and B ports of the cartridge valve adopted in (1) are connected to the second merging line 61, and the shuttle valve 63 and the direction switching valve 64 are mounted on the cover so as to overlap each other.

Also in this case, when the switching commands S1 and S2 both indicate non-merging, the cartridge valves 52 and 62 both receive a high pilot pressure and maintain the closed state by the spring force, so that the pump discharge The lines 13 and 23 are separated so that the hydraulic drive systems 10 and 20 operate independently and separately. Further, when the switching command S1 instructs merging, the pilot pressure of the cartridge valve 52 changes to the cartridge valve 52.
The pressure of the port B of the cartridge valve 52
Becomes a check valve state. Then, the pump discharge line 23
From the first discharge line 1 through the first merging line 51
The flow towards 3 flows freely, while the reverse flow is blocked.

Similarly, when the switching command S2 instructs the merging, the cartridge valve 62 is in the check valve state in the opposite direction, so that it exits from the pump discharge line 13 and passes through the second merging line 61 to the pump discharge line 61. The flow towards 23 is free flowing while the reverse flow is blocked. Thus, also in this case, the pressure oil discharged from the plurality of pump units 12 and 22 merges, and the large amount of pressure oil thus obtained drives the actuator 12 or the actuator 24 at high speed. Moreover, at that time, the seat valves 52, 6
Since 2 functions as a check valve, the cut-off characteristic at the time of shifting from the flow rate control to the pressure control is not impaired.

[0049]

[Third Embodiment] The hydraulic control system of the present invention, whose circuit diagram is shown in FIG. 3, is different from that of the first embodiment described above.
The second merging line 61, the seat valve 62, the shuttle valve 63, and the direction switching valve 64 are omitted from the merging circuit 50, and the switching control unit 44 is changed to the switching control unit 34 accordingly.

In this case, the remaining first merging line 51, seat valve 52, shuttle valve 53, and direction switching valve 54 support unidirectional merging from the hydraulic drive system 20 to the hydraulic drive system 10. It Then, in response to the switching command S1, the hydraulic drive systems 10 and 20 operate separately and independently, or the hydraulic drive systems 20 operate cooperatively in such a manner that they join and depend on the hydraulic drive system 10.

Thus, also in this case, the hydraulic drive similar to that in the conventional example (FIG. 5) is performed, but in this case, the large directional valve 33 is removed while the pilot circuit 5 introduced.
Since 3 + 54 is small, a hydraulic control system capable of unidirectional merging is realized compactly.

[0052]

[Fourth Embodiment] The hydraulic control system of the present invention, whose circuit diagram is shown in FIG. 4, is different from that of the second embodiment described above.
The second merging line 61, the cartridge valve 62, and the shuttle valve 63 are omitted, and the remaining direction switching valve 64 is transferred to the pilot circuit of the cartridge valve 52.

The direction switching valve 64 is a port B of the cartridge valve 52 in the pilot line of the cartridge valve 52.
And a line connected to the port of the shuttle valve 53, the pilot line is switched to the switching command S2.
It is designed to open and close according to. This directional valve 6
4 is added to the directional control valve 54 remaining on the port A side of the cartridge valve 52 and the shuttle valve 53 remaining on the pilot side of the cartridge valve 52, so that the function of the pilot circuit is expanded. That is, when the operating state of the cartridge valve 52 is set to the check valve state, either one of the pressures of both ports A and B of the cartridge valve 52 is selected when the pilot pressure is generated.

Also in this case, when the switching commands S1 and S2 both indicate non-merging, the cartridge valve 52 maintains the closed state by the spring force, so that the pump discharge lines 13 and 2 are closed.
3, the hydraulic drive systems 10 and 20 operate independently and separately. Further, when the switching command S1 instructs the merging, the pilot pressure of the cartridge valve 52 is set to the pressure of the port B of the cartridge valve 52, so that the cartridge valve 52 is in the check valve state. The flow from the pump discharge line 23 to the pump discharge line 13 via the first merging line 51 flows freely, while the reverse flow is blocked.

Further, when the switching command S2 instructs the merging, the pilot pressure of the cartridge valve 52 is set to the pressure of the port A of the cartridge valve 52, so that the cartridge valve 52 is in the reverse check valve state. Becomes Then, the first merging line 51 exits from the pump discharge line 13.
The flow toward the pump discharge line 23 through the flow freely flows, while the reverse flow is blocked. Thus, even if the seat valve is reduced to only the cartridge valve 52, the pressure oil discharged from the plurality of pump units 12, 22 merges in any direction, and the actuator 12 is driven by the large flow pressure oil obtained thereby. Alternatively, the actuator 24 is driven at high speed. Therefore, the hydraulic control system capable of bidirectional merging is more compact. Further, if the direction switching valve 54 and the direction switching valve 64 are combined into a three-position direction switching valve, the size will be further reduced.

[0056]

[Others] In each of the above embodiments, the hydraulic circuit has been described as a specific example, but the application of the present invention is not limited to this, and may be applied to hydraulic equipment or other hydraulic devices. Further, it is not limited to the merging of two systems, and may be expanded to the merging of three or more systems. Furthermore, the switching commands S1, S2
When both are significant at the same time, the switching control unit 44 may ignore them or may issue an alarm in order to reliably avoid malfunction.

[0057]

As is apparent from the above description, in the hydraulic control system according to the first solution of the present invention, both functions of direction switching and check are integrated in the seat valve. As a result, the directional control valve is disengaged from the merging line, and there is an advantageous effect that a hydraulic control system with a small merging circuit can be realized.

Further, in the hydraulic control system according to the second solution of the present invention, the occupancy of the installation location of the pilot circuit is eliminated, and it is possible to locally modify it, thereby merging. This has an advantageous effect that a hydraulic control system having a small circuit can be easily realized.

Furthermore, in the hydraulic control system according to the third means of solving the problems of the present invention, the double check valve functions are integrated into a single seat valve, so that the two-way merging is performed. There is an advantageous effect that a hydraulic control system capable of achieving the above can be realized in a smaller size and more easily.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a first embodiment of a hydraulic control system of the present invention.

FIG. 2 is a hydraulic circuit diagram of a second embodiment of the hydraulic control system of the present invention.

FIG. 3 is a hydraulic circuit diagram of a third embodiment of the hydraulic control system of the present invention.

FIG. 4 is a hydraulic circuit diagram of a fourth embodiment of the hydraulic control system of the present invention.

FIG. 5 is a circuit diagram of a conventional hydraulic control system.

FIG. 6 is a circuit diagram of the pump unit.

FIG. 7 is a circuit diagram of a hydraulic control system expected when duplexing the merging.

[Explanation of symbols]

10 hydraulic drive system (first hydraulic drive system) 11 electronic circuit (control unit in each drive system, electronic control unit) 12 pump unit (electronically controllable variable displacement pump) 13 pump discharge line 14 actuator (hydraulic pressure) Cylinder, hydraulic motor, load) 20 Hydraulic drive system (second hydraulic drive system) 21 Electronic circuit (control unit in each drive system, electronic control device) 22 Pump unit (variable displacement pump capable of electronic control) 23 Pump discharge line 24 Actuator (hydraulic cylinder, hydraulic motor, load) 30,40 Confluence circuit 31,41 Flow paths 32,42 Check valves 33,43 Directional switching valves 34,44 Switching control unit (switching control means for multiple drive systems) , Electronic control unit) 50 merge circuit 51 first merge line (flow path) 52 seat valve (first check valve, first cartridge valve / logic valve) ) 53 shuttle valve (first pilot circuit) 54 directional switching valve (first pilot circuit) 61 second merging line (flow path) 62 seat valve (second check valve, second cartridge valve / logic valve) 63 shuttle valve (Second pilot circuit) 64 Directional switching valve (Second pilot circuit)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumiaki Shibuya             2-16-46 Minami Kamata, Ota-ku, Tokyo Stocks             Company Tokimec (72) Inventor Kazuyuki Kihara             2-16-46 Minami Kamata, Ota-ku, Tokyo Stocks             Company Tokimec F term (reference) 3H045 AA16 AA24 AA33 BA00 BA28                       CA28 DA11 EA34 EA43                 3H089 AA60 AA72 AA80 BB27 CC01                       CC08 CC11 DA03 DA07 DB33                       DB37 DB43 DB68 EE36 GG01                       JJ05

Claims (5)

[Claims] 1. A plurality of hydraulic drive systems for performing flow rate control and pressure control for a variable displacement pump that hydraulically drives a load,
In a hydraulic control system including a merging circuit provided over both pump discharge lines, the merging circuit is
A first merging line and a second merging line that connect the pump discharge lines to each other, a first seat valve inserted in the first merging line, and a pilot pressure supplied to the first seat valve to selectively operate them. A first pilot circuit that is in a closed state or a check valve state, and a second pilot circuit that is inserted in the second merging line.
A seat valve; and a second pilot circuit that supplies pilot pressure to the seat valve to selectively close its operating state or a check valve state opposite to the first seat valve. A hydraulic control system characterized by. 2. One or both of the first pilot circuit and the second pilot circuit are mounted on a corresponding seat valve to generate pilot pressure from both port pressures thereof. Item 1. A hydraulic control system according to item 1. 3. A plurality of hydraulic drive systems that perform flow rate control and pressure control for a variable displacement pump that hydraulically drives a load,
In a hydraulic control system including a merging circuit provided over both pump discharge lines, the merging circuit is
A seat valve inserted in a merging line for communicating the pump discharge lines with each other, and a pilot circuit for supplying a pilot pressure to the merging line to selectively switch its operating state to a closed state or a check valve state Is a hydraulic control system. 4. The hydraulic control system according to claim 3, wherein the pilot circuit is mounted on the seat valve to generate a pilot pressure from both port pressures of the seat valve. 5. The seat valve is in a check valve state when either one of the two port pressures is selected and led to pilot pressure, and the flow direction is switched according to the selection of the port at that time. The pilot circuit selects one of the two port pressures of the seat valve when generating the pilot pressure when the operating state of the seat valve is set to the check valve state. 4. The hydraulic control system according to 4.