JPH10311305A - Control method for regenerative circuit and control device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for a regenerative circuit and a control device therefor whereby a regenerative effect is more enhanced, and an actuator can be operated at a higher speed. SOLUTION: From a main pump 21, working fluid is supplied to a head chamber 6 of an arm cylinder 5 via a main spool 1. At the same time, a part of the working fluid discharged from a rod chamber 7 of the arm cylinder 5 is regeneratively supplied to a side of the head chamber 6 of the arm cylinder 5 via a regenerative spool 13. An opening area of the regenerative spool 13 is controlled by a pilot-operated pressure reducing valve 18 in a pilot line 11 branching from a pilot line 2 controlling the main spool 1. In this pressure reducing valve 18, a pilot primary pressure Ps is controlled to be reduced by an external pilot pressure Pi in accordance with a rotational speed of an engine 22 driving a pump 21, a pilot secondary pressure Ps' is supplied to a pilot pressure working part of the regenerative spool 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a reproduction circuit in a construction machine or the like and a control device therefor.

[0002]

2. Description of the Related Art As shown in FIG. 7, in a hydraulic shovel, an upper revolving unit c is rotatably provided on a lower traveling unit a via a revolving unit b, and a front work machine d is mounted on the upper revolving unit c. Is provided. In the front working machine d, a base end of a boom e is rotatably supported by an upper revolving unit c, an arm f is rotatably supported at a distal end of the boom e, and a bucket is provided at a distal end of the arm f. g is rotatably supported. The boom e is rotated by a boom cylinder h, the arm f is rotated by an arm cylinder i, and the bucket g is rotated by a bucket cylinder j.

[0003] In the following description, the term "arm-in" means a movement in which the arm cylinder i of the hydraulic excavator is operated in the extension direction to pull the arm f in the direction in which the cab k is located.

FIG. 4 shows an example of a hydraulic circuit in which a valve with a built-in arm-in regeneration circuit (hereinafter referred to as an arm regeneration valve) is directly attached to an arm switching section of a conventional pilot-operated control valve.

In this conventional hydraulic circuit, when a pilot pressure Ps is supplied to an arm extension operation pilot line 2 in an arm operation control main spool 1 of a pilot operation type control valve, the main spool 1 moves rightward on the paper surface. And the pressure oil supplied from the hydraulic pressure source 3 passes through the main oil passage 4 and passes through an arm cylinder (hereinafter simply referred to as a cylinder) 5 as a fluid pressure actuator.
The oil in the rod chamber 7 flows out through the main oil passage 8 to the tank oil passage 9 so that the rod 10
Moves in the extension direction (rightward).

At this time, when the pilot pressure Ps is supplied to the pilot pressure action chamber of the regeneration spool 13 in the arm regeneration valve 12 through the pilot line 11 branched from the arm extension operation pilot line 2, the regeneration spool 13 Since the pressure is switched to the upper side of the drawing, while the internal pressure of the head chamber 6 is lower than the internal pressure of the rod chamber 7 (for example, while the arm f is lowered by its own weight), a part of the return oil from the rod chamber 7 is Since the gas passes through the check valve 15 and further flows into the head chamber 6 via the regeneration spool 13, compared with the case without the regeneration circuit,
The amount of oil supplied to the head chamber 6 increases, and the arm extension speed increases.

At this time, the return oil control opening 16 of the main spool 1 is usually narrowed sufficiently to increase the amount of regenerated oil from the rod chamber 7 to the head chamber 6 and to enhance the regenerating effect. When the head-side pressure becomes higher than the rod-side pressure and the regenerative oil is blocked by the check valve 15 and the regeneration is not performed, the amount of oil passing through the throttle portion at the return oil control opening 16 of the main spool 1 increases. In order to prevent excessive boost pressure from being generated in the main oil passage 8, a so-called unload valve 17, which releases oil in the oil passage 8 to the tank when the head side pressure exceeds a certain value, in order to prevent this, is provided. I have it.

[0008]

Generally, in a hydraulic excavator, when a negative pressure is generated in a cylinder, operability is significantly deteriorated, and it is necessary to prevent the negative pressure from being generated. FIG. 5 shows a simplified circuit for explaining the arm-in regeneration circuit when the cylinder 5 is moving at a constant speed.

The head-side pressure receiving area and the rod-side pressure receiving area of the piston of the cylinder 5 are AH and AR, respectively, and the internal pressures of the head chamber 6 and the rod chamber 7 are P, respectively.
H and PR, and the pump flow rate discharged from the hydraulic pressure source 3 is Q
1, the inflow flow rate into the cylinder 5 is Q2, the outflow flow rate from the cylinder 5 is Q3, the regeneration flow rate from the rod side to the head side is Q4, and the tank is returned through the return oil control opening 16 of the main spool 1. The flow rate flowing out to the regenerative spool 13 is defined as S1 and the maximum opening area of the return spool control opening 16 of the main spool 1 is defined as S1.
2, and for the sake of convenience, when the pressure loss in the oil passage is ignored, the following equation holds in FIG. 5 on the assumption that no negative pressure is generated on the head side.

[0010] Q2 = Q1 + Q4 Q3 = Q4 + Q5 Q2 = (AH / AR) · Q3 Q4 = K · (PR-PH) ^1/2 · S1 Q5 = K · (PR) ^1/2 · S2 AH · PH = AR * PR = constant where K is a constant.

From the above equations, the following equation (1) is derived.

K · (PR−PH) ^1/2 · S1 = {AR / (AH−AR)} · Q1−K · {AH / (AH−AR)} · (PR) ^1/2 · S2 1) Therefore, in this prior art, even if the maximum opening area S1 of the regenerating spool 13 shown in FIG. 6 is set larger to increase the regenerating flow rate and increase the cylinder speed, the above equation (1) is used. Since no negative pressure is generated in the cylinder 5, the maximum opening area S1 is determined by the minimum pump flow rate Q1 at the minimum engine speed, so that the maximum speed of the cylinder cannot be further increased.

As described above, in the regeneration circuit typified by the arm-in regeneration circuit of the hydraulic shovel, in the related art, the maximum opening area S1 of the regeneration spool is determined in consideration of the prevention of negative pressure generation at the minimum pump flow rate. Therefore, it was not possible to enhance the reproduction effect and achieve a higher actuator speed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control method and a control device of a reproduction circuit capable of enhancing a reproduction effect and operating an actuator at a higher speed.

[0015]

According to the first aspect of the present invention, a working fluid is supplied from a pump to a hydraulic actuator, and at the same time, a part of the working fluid discharged from the hydraulic actuator is passed through a regeneration spool. In a regeneration circuit for regenerating to the working fluid supply side of a pressure actuator, this is a control method of a regeneration circuit for controlling an opening area of a regeneration spool in accordance with a flow rate of a working fluid supplied from a pump.

By controlling the opening area of the regeneration spool in accordance with the flow rate of the working fluid supplied from the pump, if the flow rate supplied from the pump is large, the regeneration flow rate is increased accordingly, and the fluid pressure actuator is controlled. Works faster.

According to a second aspect of the present invention, in the control method of the regeneration circuit according to the first aspect, the controlling according to the flow rate of the working fluid supplied from the pump comprises: It is to control according to.

The opening area of the regeneration spool is controlled in accordance with the engine speed, and the regeneration flow rate increases as the engine speed increases, and the fluid pressure actuator operates at a higher speed.

According to a third aspect of the present invention, a working fluid is supplied from a pump to a hydraulic actuator,
In a regeneration circuit for regenerating a part of the working fluid discharged from a hydraulic actuator to a working fluid supply side of a hydraulic actuator via a regeneration spool, an opening area of the regeneration spool is adjusted according to a flow rate of the working fluid supplied from a pump. It is a control device of a reproduction circuit including a reproduction spool control means for controlling.

The opening area of the regenerating spool is controlled by the regenerating spool control means in accordance with the flow rate of the working fluid supplied from the pump. Increase speed.

According to a fourth aspect of the present invention, the regeneration spool control means in the control device of the regeneration circuit according to the third aspect controls the pilot primary pressure applied to the main spool of the pilot operated control valve for controlling the fluid pressure actuator. And a pilot-operated pressure reducing valve that controls the pressure by an external pilot pressure signal corresponding to the rotation speed of the engine that drives the pump, and supplies the pressure as a pilot secondary pressure to the pilot pressure operating section of the regeneration spool.

A pilot-operated pressure reducing valve is incorporated in the pilot line to the regeneration spool, and the opening area of the regeneration spool is controlled by increasing or decreasing the external pilot pressure in accordance with the engine speed. Increase the regeneration effect and operate the fluid pressure actuator at higher speed.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIGS.

FIG. 1 shows an example of a hydraulic circuit when an arm-in regeneration valve is directly attached to an arm switching section of a control valve according to the present invention.

In FIG. 1, the same parts as those of the conventional example shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

An arm cylinder (hereinafter simply referred to as a cylinder) 5 as a fluid pressure actuator is provided in the pilot pressure action chambers at both ends facing the main spool 1 for controlling the arm operation of the pilot operated control valve. A pilot line 2 for in-operation and a pilot line 2a for operating the arm to the outside are connected to each other.

Pilot line 2 for arm-in operation
A pilot-operated pressure reducing valve (hereinafter simply referred to as a pressure reducing valve) as a regenerating spool control means controlled by an external pilot pressure Pi
18 primary ports are connected.

The drain port of the pressure reducing valve 18 is connected to the drain line of the regeneration spool 13 via a drain line 19. The secondary port of pressure reducing valve 18 is connected to pilot line 20
Thereby, it is electrically connected to the pilot pressure action chamber of the regeneration spool 13.

The switching pilot pressure supplied to the pilot line 2 of the main spool 1 is referred to as a pilot primary pressure Ps, and the pilot pressure of the pilot line 20 controlled by the pressure reducing valve 18 is referred to as a pilot secondary pressure Ps'.

The hydraulic source 3 connected to the hydraulic oil supply side of the main spool 1 supplies at least hydraulic oil to the main spool 1.
A main pump 21 that supplies the main pump 21, and an engine 22 that drives the main pump 21.

As an example of the control method, an engine speed sensor 23 for detecting the speed of the engine 22 is attached to the engine 22. The engine speed sensor 23
Shows the case where the electric signal line 24 is connected to the input terminal of the controller 25.

The controller 25 has a central processing unit (C
PU), read-only memory for program (RO)
M), a random access memory (RA) for storing data
M), etc., and performs an arithmetic processing on the input engine speed and the like.

A pilot line 26 for supplying the external pilot pressure Pi to the pressure reducing valve 18 is provided with, for example, an electromagnetic proportional pressure reducing valve 27.
Is connected to the pilot pump 28 via the.

The electromagnetic proportional pressure reducing valve 27 is an electric / hydraulic conversion valve having a solenoid 30 supplied with current from the controller 25 via an electric signal line 29 and a spool which operates in proportion to the supplied current. The electromagnetic proportional pressure reducing valve 27 outputs an external pilot pressure Pi.

Here, the pressure reducing valve 18 controls the pilot secondary pressure Ps' by the external pilot pressure Pi as shown in FIG. 2 irrespective of the pilot primary pressure Ps.

Further, the relationship between the spool opening area As1 of the regeneration spool 13 and the pilot secondary pressure Ps' is as shown in FIG.

Next, the operation of the embodiment shown in FIGS. 1 to 3 will be described.

As described above, in the prior art, the reproduction spool 13 is used.
The maximum opening area S1 is determined by the minimum pump flow rate Q1 at the minimum engine speed of the body, but in the present embodiment, an external pilot pressure reducing valve 18 is incorporated in the pilot lines 11 and 20 of the regeneration circuit, and the engine speed is reduced. The pressure reducing valve 18 is controlled by the external pilot pressure Pi according to the number,
By controlling the stroke (opening area) of the regenerating spool 13, the opening area of the regenerating spool 13 at each time the engine speed can be set to an allowable maximum area that does not generate a negative pressure in the cylinder 5.

That is, as shown in FIG. 3, when the engine speed is low, the external pilot pressure Pi is increased and the pilot secondary pressure Ps' is reduced, so that a negative pressure is not generated in the cylinder 5. Limiting the maximum opening area, as the engine speed increases, the controller
By lowering the external pilot pressure Pi at 25 and the electromagnetic proportional pressure reducing valve 27, the pilot secondary pressure Ps' is increased, and the opening area of the regenerating spool 13 is further increased. The reproduction effect can be further enhanced, and a higher cylinder speed can be realized.

Next, an embodiment (not shown) included in the present invention will be described.

In the above description of the embodiment, the case of the arm-in regeneration circuit has been described as an example. However, the invention is not limited thereto, and the working machine of another construction machine such as a boom regeneration circuit or a bucket regeneration circuit in a hydraulic shovel or a loader may be used. The present invention can be applied to various reproduction circuits such as a reproduction circuit for use.

Further, the control method of the external pilot pressure Pi is not limited to the method exemplified in the description of the embodiment, but may be various.

Further, the flow rate of the hydraulic oil discharged from the main pump 21 may be detected by a flow rate sensor, and the pressure reducing valve 18 may be controlled via the controller 25 and the electromagnetic proportional pressure reducing valve 27.

Finally, when the pressure reducing valve 18 is of the electromagnetic proportional type in which the solenoid operates proportionally, the external pilot pressure P
The electromagnetic proportional pressure reducing valve may be directly controlled by the output current from the controller 25 instead of i.

[0045]

According to the first aspect of the present invention, by controlling the opening area of the regeneration spool according to the flow rate of the working fluid supplied from the pump, the regeneration flow rate is increased according to the increase in the supply flow rate from the pump. And the regeneration effect is higher than in the prior art, and the fluid pressure actuator can be operated at a higher speed.

According to the second aspect of the present invention, since the opening area of the regeneration spool is controlled by grasping the flow rate of the working fluid supplied from the pump based on the engine speed, unlike the prior art, the engine speed is reduced. It is possible to cope with the increase, the regeneration flow rate is increased in accordance with the increase in the engine speed, and the fluid pressure actuator can be operated at a higher speed.

According to the third aspect of the present invention, since the opening area of the regeneration spool is controlled by the regeneration spool control means in accordance with the flow rate of the working fluid supplied from the pump, the regeneration effect increases as the supply flow rate from the pump increases. Higher,
The fluid pressure actuator can be operated at higher speed.

According to the fourth aspect of the present invention, a pilot-operated pressure reducing valve is incorporated in the pilot line to the regeneration spool, and the external pilot pressure acting on the pressure reducing valve is increased or decreased according to the engine speed. Since the opening area of the regeneration spool is controlled by the pressure reducing valve, unlike the prior art, it is possible to cope with an increase in the engine speed, and as the engine speed increases, the regeneration effect is further enhanced, and the fluid pressure actuator can be operated at higher speed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a control method and a control device of a reproduction circuit according to the present invention.

FIG. 2 is a characteristic diagram showing operation characteristics of an external pilot pressure reducing valve in the control device.

FIG. 3 is a characteristic diagram showing operation characteristics of a reproduction spool in the control device.

FIG. 4 is a circuit diagram showing a conventional reproducing circuit.

FIG. 5 is a simplified explanatory diagram of a conventional reproducing circuit.

FIG. 6 is a graph showing operating characteristics of a reproduction spool in a conventional reproduction circuit.

FIG. 7 is a front view of the hydraulic excavator.

[Explanation of symbols]

1 Main Spool 5 Arm Cylinder as Fluid Pressure Actuator 13 Regeneration Spool 18 Pilot Operated Pressure Reducing Valve as Regeneration Spool Control Means 21 Pump 22 Engine

Claims (4)

[Claims] A regeneration circuit for supplying a working fluid from a pump to a hydraulic actuator and simultaneously regenerating a part of the working fluid discharged from the hydraulic actuator to a working fluid supply side of the hydraulic actuator via a regeneration spool. A method of controlling a regeneration circuit, wherein an opening area of a regeneration spool is controlled according to a flow rate of a working fluid supplied from a pump. 2. The regeneration circuit according to claim 1, wherein the control according to the flow rate of the working fluid supplied from the pump is performed according to the rotation speed of an engine that drives the pump. Control method. 3. A regeneration circuit for supplying a working fluid from a pump to a hydraulic actuator and simultaneously regenerating a part of the working fluid discharged from the hydraulic actuator to a working fluid supply side of the hydraulic actuator via a regeneration spool. A regeneration circuit control device, comprising: regeneration spool control means for controlling an opening area of a regeneration spool in accordance with a flow rate of a working fluid supplied from a pump. 4. The regenerative spool control means controls a primary pressure of a pilot applied to a main spool of a pilot-operated control valve for controlling a fluid pressure actuator by an external pilot pressure signal corresponding to a rotation speed of an engine for driving the pump. 4. The control device for a regeneration circuit according to claim 3, further comprising a pilot-actuated pressure reducing valve for supplying a pilot secondary pressure to a pilot pressure operating portion of the regeneration spool.