JPH08219107A - Hydraulic regeneration device for hydraulic machinery - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a hydraulic regeneration device for a hydraulic machine capable of easily realizing drive control of an actuator suitable for desired work of heavy load work and light load work. A control device 44 for outputting an actuation signal is according to a pressure signal PD from a pressure detector 29 to an electromagnetic proportional pressure reducing valve 40 is provided, and the control device 44 responds to the pressure signal PD and the actuation signal is. Based on the storage unit 62 that stores the functional relationship with the target current i as the functional relationship 101 corresponding to the heavy load work and the functional relationship 100 corresponding to the light load work, and the pressure signal PD and the functional relationships 101 and 100, The calculation unit 61 includes a calculation unit 61 that calculates a corresponding target current i, and includes a work mode switch 41 that can output instruction signals MS corresponding to heavy load work and light load work to the control device 44. , According to the instruction signal MS
The target current i is obtained based on the corresponding functional relationship among the functional relationships 101 and 100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic regenerator which is provided in a hydraulic machine such as a hydraulic excavator and which can regenerate and supply return oil from an actuator to the actuator.

[0002]

2. Description of the Related Art As a hydraulic pressure regenerating device for a hydraulic machine of this type, there is one described in Japanese Patent Publication No. 4-59484.
FIG. 5 is a circuit diagram showing this conventional technique. As shown in FIG. 5, in this conventional technique, a hydraulic pump 1 and a pilot pump 1a, and an actuator driven by pressure oil discharged from the hydraulic pump 1, that is, a hydraulic cylinder 2 having a bottom side chamber C and a rod side chamber D are provided. A directional control valve 3 for controlling the flow of pressure oil supplied from the hydraulic pump 1 to the hydraulic cylinder 2 and having a left side switching position 3a and a right side switching position 3b is provided.

The left side switching position 3a of the directional switching valve 3 which is a switching position for driving the hydraulic cylinder 2 in the extending direction is connected to the tank side passage connected to the tank, that is, the discharge passage 6 and the hydraulic pump 1. Pump side passage, that is, the supply passage 5, the communication passage 10 that connects the supply passage 5 and the discharge passage 6, and the supply of the pressure oil from the discharge passage 6 to the supply passage 5 provided in the communication passage 10. Means for allowing the flow of the pressure oil introduced into the tank, that is, a flow rate control means for controlling the flow rate of the pressure oil introduced into the tank, that is, a merging switching device 8 for selectively blocking the discharge passage 6, and a merging passage for communicating with the supply passage 5. A pressure detecting means for guiding a pressure signal for driving the switching device 8, that is, a pressure detecting passage 9 is provided.
The pilot pressure of the pilot pump 1a is supplied as an external pressure signal Pc, that is, as a set pressure to the confluence switching device 8 so as to oppose the pressure signal guided in the pressure detection passage 9 described above, and a driving means for the confluence switching device 8. That is, the external pressure signal generator 15 is provided.

In the prior art thus constructed, when the direction switching valve 3 is switched to the left switching position 3a, the hydraulic pump 1
The pressure oil discharged from the hydraulic cylinder 2 passes through the supply passage 5.
To the bottom chamber side C. The pressure oil flowing out from the rod side chamber D of the hydraulic cylinder 2 is guided to the tank via the discharge passage 6. At this time, when the pressure in the supply passage 5 is guided to the pressure detection passage 9 and this pressure signal is lower than the external pressure signal Pc set by the external pressure signal generator 15,
The confluence switching device 8 is driven so as to block the discharge passage 6,
The entire amount of return oil from the rod side chamber D of the hydraulic cylinder 2 is guided from the discharge passage 6 to the supply passage 5 via the check valve 7 and joins the flow rate of the supply passage 5. As a result, the operating speed of the hydraulic cylinder 2 can be increased.

Further, the load pressure of the hydraulic cylinder 2 increases, the pressure in the supply passage 5 rises, and the pressure signal guided to the pressure detection passage 9 is larger than the external pressure signal Pc set by the external pressure signal generator 15. When the temperature rises, the merging switching device 8 is driven so that the discharge passage 6 communicates with each other, and the discharge passage 6 communicates with the tank. Therefore, the return oil from the rod side chamber D of the hydraulic cylinder 2 is returned to the tank without being joined to the supply passage 5. As a result, the acceleration of the hydraulic cylinder 2 is suppressed, and the normal speed is maintained.

As described above, in the prior art shown in FIG. 5, when the load pressure generated when the hydraulic cylinder 2 is extended is equal to or lower than the set pressure, the entire amount of the return oil from the rod side chamber D of the hydraulic cylinder 2 is stored in the bottom side chamber C. When the hydraulic cylinder 2 regenerates and joins, the hydraulic cylinder 2 is accelerated more than the normal speed, and when the load pressure generated when the hydraulic cylinder 2 is extended is larger than the set pressure, the hydraulic cylinder 2 is kept at the normal speed. ing.

[0007]

By the way, in the hydraulic machine, heavy load work requiring a large load pressure and light load work requiring a relatively low load pressure and a high working speed are selected. There are things to implement in a specific way. For example, when the hydraulic machine is a hydraulic excavator, a single hydraulic excavator can selectively perform “overburden excavation work” that is light load work and “ditch excavation work” that is heavy load work. Is often done. In this case, FIG.
In the prior art shown in, the "groove excavation work" that is a heavy load work
In order to carry out, the large thrust force is required, and therefore, it is necessary to set the set pressure, that is, the value of the external pressure signal Pc as low as possible to cancel the regeneration at a low load pressure. On the contrary, “overburden work” is a light load work.
Therefore, a large thrust is not required, and it is preferable to set the value of the pressure signal Pc as high as possible in order to obtain a high working speed.

Therefore, in the above-mentioned conventional technique, the external pressure signal Pc is taken into consideration in consideration of the "grooving work" which is a heavy load work.
If the value of is set to a low value in advance, the work speed of the "top soil stripping work", that is, the operating speed of the hydraulic cylinder 2 becomes slower, and the work efficiency of the "top soil stripping work", which is this light load work, decreases. Resulting in. On the contrary, if the value of the external pressure signal Pc is set to a high value in consideration of the "overburden work" which is a light load work, a large thrust cannot be obtained in the "groove excavation work", and this heavy load work is performed. The work efficiency of "grooving work" will be reduced. As described above, in the conventional technique, the value of the external pressure signal Pc must be uniquely determined in consideration of either heavy load work or light load work, and therefore, one heavy load work can be performed by one hydraulic machine. However, it was difficult to improve the work efficiency of both light load work.

[0009] It should be noted that this can occur even during one continuous operation. For example, in consideration of "overburden work" requiring a high work speed, when the "overburden work" is performed by setting the value of the external pressure signal Pc to a high value in advance, the bucket of the hydraulic excavator is When hitting a hard ground, a large thrust cannot be obtained because the value of the external pressure signal Pc is set to a high value, the hydraulic cylinder 2 is stopped, and the work efficiency is reduced.

The present invention has been made in view of the above-mentioned circumstances in the prior art, and an object thereof is to provide a hydraulic machine capable of selectively performing heavy load work and light load work through the operation of an actuator. An object of the present invention is to provide a hydraulic regeneration device for a hydraulic machine that can easily realize drive control of an actuator suitable for a desired work of heavy load work and light load work.

[0011]

To achieve this object, the invention according to claim 1 of the present invention will be described with reference to the reference numerals used in the embodiments shown in FIGS. become that way.

The present invention relates to the hydraulic pump 1 and the tank 30.
An actuator driven by pressure oil discharged from the hydraulic pump 1, for example, a hydraulic cylinder 2, a direction switching valve 20 controlling the flow of pressure oil supplied from the hydraulic pump 1 to the hydraulic cylinder 2, and a hydraulic pressure. The tank side passage 23 that connects the cylinder 2 and the tank 30 to each other, the flow rate control means that controls the flow rate of the pressure oil guided to the tank 30, for example, the variable throttle 25, the hydraulic pump 1 and the hydraulic cylinder 2 are connected. A pump side passage 28, a communication passage 24 that connects the pump side passage 28 and the tank side passage 23,
A check valve 21 provided in the communication passage 24 for allowing the supply of pressure oil from the tank side passage 23 to the pump side passage 28 when the pressure inside the tank side passage 23 is higher than the pressure inside the pump side passage 28. , Detecting means for detecting the pressure of the pressure oil supplied to the hydraulic cylinder 2, for example, a pressure detector 29 for detecting the discharge pressure of the hydraulic pump 1, and the variable throttle 2 described above.
A basic structure is provided with a drive means for driving the motor 5, for example, an electromagnetic proportional pressure reducing valve 40, and a regenerating operation in which the return oil from the hydraulic cylinder 2 joins the pump side passage 28 via the communication passage 24.

In addition to this basic structure, the present invention inputs the pressure signal PD from the pressure detector 29 described above and outputs an operation signal is according to the pressure signal PD to the electromagnetic proportional pressure reducing valve 40 described above. A control device 44 is provided, and the control device 44 changes the functional relationship between the pressure signal PD and a target value corresponding to the actuation signal is, for example, a target current i, to a functional relationship 101 corresponding to a predetermined heavy load work. Also, as the functional relation 100 corresponding to a predetermined light load work, a plurality of storage units 62 that are set in advance, the pressure signal PD, and the functional relations 101 and 100 stored in the storage unit 62 are used as the corresponding relations described above. Calculation unit 61 for calculating the target current i
Have and.

Further, there is provided an instruction device, for example, a work mode switch 41, capable of outputting an instruction signal MS corresponding to each of the predetermined heavy load work and the predetermined light load work to the control device 44.

Then, the arithmetic unit 61 of the control device 44.
Is a functional relation 101 corresponding to a predetermined heavy load work and a functional relation 100 corresponding to a predetermined light load work stored in the storage unit 62 according to the instruction signal MS output from the work mode switch 41. The target current i is calculated based on the corresponding functional relationship among the above.

[0016]

Since the invention according to claim 1 of the present invention has the above-mentioned configuration, when performing heavy load work such as "groove excavation work" in a hydraulic excavator, for example, a work mode which is an instruction device The directional control valve 2 is operated by operating the switch 41 to output the instruction signal MS corresponding to the heavy load work.
The switching operation of 0 may be performed. In response to the instruction signal MS output from the work mode switch 41, the control device 4
The calculation unit 61 of No. 4 calculates the target current i based on the functional relationship 101 stored in the storage unit 62 corresponding to the heavy load work shown in FIG. 3 and the pressure signal PD output from the pressure detector 29. Perform calculations.

Here, the functional relation 1 corresponding to heavy load work 1
01 is a functional relationship such that when the value of the pressure signal PD is relatively small, the variable throttle 25, which is the flow rate control means, can be fully opened, that is, the value of the pressure signal PD is relatively small (FIG. 3).
Pd ₂ ) is a functional relationship that can cancel the playback operation.

The drive signal is corresponding to the target current i based on the functional relation 101 is output from the control device 44 to the electromagnetic proportional pressure reducing valve 40 which is the drive means. As a result, the electromagnetic proportional pressure reducing valve 40 is driven, and the variable throttle 25 is fully opened when the pressure signal PD is relatively small (Pd _{2 in} FIG. 3), and operates so as to pass the tank side passage 23 entirely. As a result, the reproduction operation is released. Therefore, the pressure oil of the hydraulic pump 1 is supplied to the hydraulic cylinder 2 which is an actuator via the pump side passage 28 and the direction switching valve 20, and the return oil of the hydraulic cylinder 2 is supplied via the direction switching valve 20 and the tank side passage 23. The entire amount can be returned to the tank 30. As a result, a large thrust is obtained and it is possible to cope with heavy load work.

When carrying out light load work such as "overburden work" in a hydraulic excavator, the work mode switch 41, which is an indicating device, is operated to output an instruction signal MS corresponding to the light load work. Directional valve 2
The switching operation of 0 may be performed. The control device 44 is responsive to the instruction signal MS output from the work mode switch 41.
The calculation unit 61 calculates the target current i based on the functional relationship 100 stored in the storage unit 62 corresponding to the light load work shown in FIG. 3 and the pressure signal PD output from the pressure detector 29. Perform.

Here, the functional relation 1 corresponding to light load work
00 is a functional relationship in which the variable throttle valve 25, which is the flow rate control means, is not fully opened while the value of the pressure signal PD is relatively small (for example, Pd _{2 in} FIG. 3), that is, the value of the pressure signal PD is relatively small. The interval (for example, Pd _{2 in} FIG. 3) is a functional relationship that enables the reproduction operation.

A drive signal is corresponding to the target current i based on the functional relation 100 is output from the control device 44 to the electromagnetic proportional pressure reducing valve 40 which is a drive means. As a result, when the electromagnetic proportional pressure reducing valve 40 is driven and the variable throttle 25 is not fully opened when the value of the pressure signal PD is small (for example, Pd _{2 in} FIG. 3), the oil tank 30 in the tank side passage 23 is not opened.
Regulate the inflow to. Along with this, the pressure in the tank side passage 23 rises, and the regenerating operation becomes possible. When the pressure in the tank-side passage 23 becomes larger than the pressure in the pump-side passage 28, the pressure oil in the tank-side passage 23 becomes the communication passage 24,
It joins the pump-side passage 28 via the check valve 21.
Therefore, the return oil of the hydraulic cylinder 2 and the hydraulic pump 1
The pressure oil combined with the pressure oil discharged from is supplied to the hydraulic cylinder 2. As a result, the hydraulic cylinder 2 can be driven at a higher operating speed than the normal speed, which is the operating speed of the hydraulic cylinder 2 during heavy load work described above,
It can be used for light load work.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic pressure regenerating apparatus for a hydraulic machine according to the present invention will be described below with reference to the drawings. 1 to 4 are views showing an embodiment of a hydraulic pressure regenerating apparatus for a hydraulic machine corresponding to claims 1 to 7 of the present invention. FIG. 1 is a circuit diagram showing the overall configuration, and FIG.
FIG. 3 is a diagram showing a configuration of a control device provided in the embodiment shown in FIG. 3, FIG. 3 is a diagram showing a configuration of a storage unit and a calculation unit of the control device shown in FIG. 2, and FIG. 4 shows characteristics obtained in the embodiment shown in FIG. FIG.

This embodiment is applied to, for example, a hydraulic excavator, and as shown in FIG. 1, an engine 43, a hydraulic pump 1 driven by this engine 43, and a tank 3.
0, actuators such as boom cylinders, arm cylinders, and bucket cylinders driven by pressure oil discharged from the hydraulic pump 1, that is, the hydraulic cylinder 2, and the flow rate of the pressure oil supplied from the hydraulic pump 1 to the hydraulic cylinder 2. And a directional control valve 20 for switching. Direction switching valve 2
0 has a neutral position, a switching position 20a capable of supplying pressure oil to the bottom side chamber C of the hydraulic cylinder 2, and a switching position 20b capable of supplying pressure oil to the rod side chamber D of the hydraulic cylinder 2. The direction switching valve 20 is switched to either of the switching positions 20a and 20b by selectively operating the pilot pressures Pa and Pb by operating the operation lever 71 of the pilot valve 70.

Further, a tank side passage 23 connecting the hydraulic cylinder 2 and the tank 30 and a flow rate control means arranged in the tank side passage 23 for controlling the flow rate of the pressure oil guided to the tank 30, for example, a hydraulic operation type. The variable diaphragm 25 of FIG. The variable diaphragm 25 has a communication position 25a and a diaphragm position 25b.

Further, a pump side passage 28 that connects the hydraulic pump 1 and the hydraulic cylinder 2 to each other, a communication passage 24 that connects the pump side passage 28 and the tank side passage 23, and a tank provided in the communication passage 24 When the pressure in the side passage 23 is higher than the pressure in the pump side passage 28, the supply of pressure oil from the tank side passage 23 to the pump side passage 28 is allowed to proceed from the pump side passage 28 toward the tank side passage 23. Check valve 21 for blocking the flow of pressure oil of the tank and the tank side passage 2
3 is provided with a check valve 22 that allows the flow of pressure oil from the hydraulic pump 1 toward the direction switching valve 20 and blocks the flow of pressure oil from the direction switching valve 20 toward the hydraulic pump 1. .

Further, a detection means for detecting the pressure of the pressure oil supplied to the hydraulic cylinder 2, for example, the discharge pressure Pd of the hydraulic pump 1 is detected and the pressure signal, that is, the pump discharge pressure signal PD.
Is provided with a pressure detector 29 for outputting the variable throttle 25 and an electromagnetic proportional pressure reducing valve 40 for outputting the pilot pressure Pi to the pilot chamber of the variable throttle 25, for example.

In particular, in this embodiment, the pressure detector 2
A control device 44 for inputting the pump discharge pressure signal PD output from 9 and outputting an operation signal is corresponding to the pump discharge pressure signal PD to the electromagnetic proportional pressure reducing valve 40 described above, and for a heavy load work and a light load work. An instruction device for instructing any one of them, for example, an instruction signal M corresponding to the selected work mode
A work mode switch 41 for outputting S is provided.

As shown in FIG. 2, the above-mentioned control device 44 controls the pump discharge pressure signal P output from the pressure detector 29.
D, the input section 60 for inputting the instruction signal MS output from the work mode switch 41, the above-described pump discharge pressure signal PD, and the operation signal i for operating the electromagnetic proportional pressure reducing valve 40.
For driving the electromagnetic proportional pressure reducing valve 40 and a storage unit 62 in which a plurality of functional relationships with a target value corresponding to s, for example, a target current i, are set in advance for heavy load work and light load work respectively. The calculator 61 includes a calculator 61 for calculating the target current i, and an output unit 63 for outputting an actuation signal is corresponding to the target current i calculated by the calculator 61 to the electromagnetic proportional pressure reducing valve 40.

In the storage unit 62 of the control device 44 described above,
For example, the functional relation 100 corresponding to the light load work shown in FIG.
And a functional relationship 101 corresponding to heavy load work are set. Of these, the functional relation 101 corresponding to heavy load work
Outputs a high constant target current i ₁ until the pump discharge pressure signal PD reaches a predetermined low first set pressure Pd ₁ ,
Until the pump discharge pressure signal PD exceeds the first set pressure Pd ₁ and reaches the second set pressure Pd ₂ , a target current i that satisfies i ₀ <i <i ₁ is output, and the pump discharge pressure signal PD Is the second
When the set pressure Pd _{2 is} equal to or higher than, the target current i having a current value i ₀ = 0 is output. Further, the functional relationship 100 corresponding to the light load work outputs a high constant target current i ₁ until the pump discharge pressure signal PD reaches the above-described predetermined low first set pressure Pd ₁ , and outputs the pump discharge pressure signal. The target current i (i ₀ <i <i ₁ ) decreases in accordance with the increase of the pump discharge pressure signal PD until Pd reaches the third set pressure Pd ₃ which is larger than the above-mentioned second set pressure Pd _2. When the pump discharge pressure signal PD becomes equal to or higher than the third set pressure Pd ₃ , the target current i of i ₀ = 0 is output. That is, the functional relation 101 corresponding to the heavy load work
Is set in advance larger than the gain of the functional relation 100 corresponding to the light load work.

Further, the arithmetic unit 61 of the control device 44 described above.
Is an instruction signal M output from the work mode switch 41.
In accordance with S, the corresponding functional relation among the functional relation 101 corresponding to the heavy load work and the functional relation 100 corresponding to the light load work stored in the storage unit 62, and the pressure detector 29 output. The target current i is calculated based on the pump discharge pressure signal PD.

The operation of the embodiment thus constructed is as follows. For example, considering "groove excavation work",
Assuming that the heavy load work is selected by the work mode switch 41 shown in FIG. 3, the instruction signal MS corresponding to the heavy load work is sent from the work mode switch 41 to the control device 4 shown in FIGS.
4 is output to the input unit 60 of the control device 44.
Functional relationships 100, 101 stored in the storage unit 62 of
Among them, the functional relation 101 corresponding to the heavy load work is selected, and the calculation unit 61 of the control device 44 determines the functional relation 101 corresponding to the heavy load work and the pump discharge pressure signal PD output from the pressure detector 29. Based on the above, the calculation for obtaining the target value of the operation signal is for operating the electromagnetic proportional pressure reducing valve 40 shown in FIG. 1, that is, the target current i is performed.

In this state, when the operating lever 71 of the pilot valve 70 is operated to, for example, the A side in FIG. 1, a pilot pressure Pa is generated, and this pilot pressure Pa is located on the left side of the direction switching valve 20 in FIG. Given to the pilot chamber, the direction switching valve 20 is switched to the switching position 20a.
As a result, the pressure oil discharged from the hydraulic pump 1 is supplied to the bottom side chamber C of the hydraulic cylinder 2 via the pump side passage 28, the check valve 22, and the switching position 20a of the directional switching valve 20, and returned from the rod side chamber D. The oil is returned to the tank 30 via the switching position 20a of the direction switching valve 20, the tank side passage 23, and the variable throttle 25.

At this time, the pump discharge pressure signal PD detected by the pressure detector 29 is the first set pressure P of the functional relation 101 stored in the storage unit 62 shown in FIG.
While it is lower than d ₁ , a high constant target current (i = i ₁ ) is obtained by the calculation unit 61, and an operation signal (is = i ₁ ) corresponding to this target current (i = i ₁ ) is output to the control device. Output from the output unit 63 of 44 to the drive unit of the electromagnetic proportional pressure reducing valve 40. As a result, the pilot pressure pi output from the electromagnetic proportional pressure reducing valve 40 is minimized, and the force of the spring provided in the variable throttle 25 causes the variable throttle 25 to provide the maximum throttle amount of FIG. Therefore, the pressure corresponding to the throttle amount of the variable throttle 25 is generated in the tank side passage 23. Then, when the pressure in the tank side passage 23 becomes equal to or higher than the pressure in the pump side passage 28, a part of the return oil from the rod side chamber D of the hydraulic cylinder 2 passes through the communication passage 24 and the check valve 21 to the pump side. An operation is performed in which the return oil flows into the passage 28, merges with the pressure oil discharged from the hydraulic pump 1, and is supplied to the bottom side chamber C of the hydraulic cylinder 2. Therefore, the flow rate flowing into the bottom side chamber C of the hydraulic cylinder 2 is as shown in FIG.
It is possible to increase the operation flow rate of the hydraulic cylinder 2 in accordance with the increase in the maximum regeneration flow rate indicated by.

From such a state, when the bucket of the hydraulic excavator is put into the soil and the "groove excavation work" is carried out and the load applied to the hydraulic cylinder 2 is increased, the discharge pressure Pd of the hydraulic pump 1 is increased and the pressure is increased. The value of the pump discharge pressure signal PD output from the detector 29 also increases.
The value of this pump discharge pressure signal PD is the functional relation 101 in FIG.
When it is between the first set pressure Pd ₁ and the second set pressure Pd ₂ , the target current i obtained by the calculation unit 61 of the control device 44 takes a value of i ₀ <i <i ₁ The actuation signal is output from the output 63 of the device 44 is also i ₀ <is
= I <i ₁ , the proportional proportional pressure reducing valve 4
The value of the pilot pressure Pi output from 0 increases, and the variable throttle 25 changes its throttle amount small as shown in FIG. 4A, that is, in the direction from the closed state to the open state. Drive to change, tank 30
The amount of oil returned to the tank increases and the regeneration flow rate gradually decreases as shown in FIG. 4 (b). That is, although the operating speed of the hydraulic cylinder 2 is slightly slower than before, a larger thrust can be obtained.

Further, when the value of the pump discharge pressure signal PD becomes equal to or higher than the second set pressure Pd ₂ of the functional relation 101 of FIG. 3, the target current i obtained by the arithmetic unit 61 of the control device 44 is i = i. ₀ , the operating signal is output from the output unit 63 also becomes is = i = i ₀ , and the value of the pilot pressure Pi output from the electromagnetic proportional pressure reducing valve 40 becomes the maximum, and the variable throttle 25 becomes As shown in (a) of the above, the switching position is switched to the fully open switching position 25a where the throttle amount is 0. As a result, the regeneration flow rate becomes 0 as shown in FIG. 4B, and the total amount of the tank-side passage 23 becomes 30
Then, the pressure in the rod side chamber D of the hydraulic cylinder 2 is reduced, and the thrust of the hydraulic cylinder 2 is increased, and the excavation force is rapidly increased.
It is possible to carry out a desired heavy-duty work, that is, “groove excavation work”.

If light load work is selected by the work mode switch 41 in consideration of, for example, "overburden work" or "leveling work" for leveling the ground, the work mode switch 41 is used for light load work. The instruction signal MS corresponding to the work is output to the input unit 60 of the control device 44. As a result, the functional relationship 100 corresponding to the light load work is selected from the functional relationships 100 and 101 stored in the storage unit 62 of the control device 44, and the storage unit 61 of the control device 44 corresponds to the light load work. Functional relationship 100 to
Based on the pump discharge pressure signal PD output from the pressure detector 29, a calculation for obtaining the target current i is performed. In this state, the operation lever 71 is operated and the directional control valve 2
When 0 is switched to the switching position 20a, for example, pressure oil is supplied to the bottom side chamber C of the hydraulic cylinder 2 and the hydraulic cylinder 2 operates in the extending direction.

At this time, while the pump discharge pressure signal PD detected by the pressure detector 29 is lower than the first set pressure Pd ₁ , the variable throttle 25 has the maximum value shown in FIG. It is held at the throttle position 25b capable of giving the throttle amount, and the pressure corresponding to the throttle amount of the variable throttle 25 can be generated in the tank-side passage 23, and the maximum regeneration flow rate shown in FIG. Playback operations can be performed. That is, in the bottom side chamber C of the hydraulic cylinder 2,
The return oil of the hydraulic cylinder 2 and the pressure oil discharged from the hydraulic pump 1 can be merged and supplied, and the operating speed of the hydraulic cylinder 2 can be increased to perform desired light load work such as "overburden work". You can Note that the load pressure slightly increases due to the resistance of soil or the like hitting the bucket tip (not shown), and the pump discharge pressure signal P output from the pressure detector 29 is output.
Even if the value of D becomes about the second set pressure Pd ₂ , the gain of the functional relation 100 relating to this light load work is
Since the gain is set smaller in advance than the gain of the functional relation 101 related to the heavy load work described above, the target current i obtained by the calculation unit 61 has a value of i ₀ <i <i ₁ ,
The operating signal is output from the output unit 63 is also i ₀ <is
= I <i ₁ , and accordingly, the electromagnetic proportional pressure reducing valve 40
The pilot pressure Pi output from the above becomes minimum <Pi <maximum, and the variable throttle 25 is maintained in a state of holding the throttle amount positioned on the characteristic line of FIG. Therefore, although the regeneration flow rate is slightly reduced as shown in FIG. 4B, the regeneration operation can be continued.

Then, when a situation corresponding to heavy load work occurs during light load work such as "surface soil stripping work", for example, when the tip of a bucket (not shown) is stuck in hard ground. In this case, since the discharge pressure pd of the hydraulic pump 1 increases as the load pressure increases,
The value of the pump discharge pressure signal PD detected by the pressure detector 29 may become large and may become, for example, the third set pressure Pd ₃ or higher. When such a situation occurs, i = i
₀ , and the operation signal is output from the output unit 63
Also, is = i = i ₀ , the pilot pressure Pi output from the electromagnetic proportional pressure reducing valve 40 becomes maximum, and the variable throttle 2
As shown in FIG. 4 (a), 5 is switched to the communication position 25a where the throttle amount is almost 0, and the entire amount of the tank-side passage 23 is returned to the tank 30 and the regeneration is canceled. In this state, as shown in FIG. 4B, the regeneration flow rate is exhausted, the rod-side chamber D of the hydraulic cylinder 2 communicates with the tank 30, and
As described above, a large thrust force of the hydraulic cylinder 2 can be secured, and the bucket that is hard to reach the hard ground can be moved to perform an operation to escape from the hard ground. That is, the light load work such as the "overburden work" can be continuously performed without causing the work to be stopped due to the stop of the hydraulic cylinder 2.

In the embodiment thus constructed, one hydraulic excavator is used for light load work in accordance with the functional relationships 100 and 101 of the control device 44 selected by the work mode switch 41 as described above. It is possible to perform the drive control of the hydraulic cylinder 2 that is suitable for both heavy load work, and thus it is possible to improve the work efficiency of both light load work and heavy load work.

In the above embodiment, the pressure detector 29 for detecting the discharge pressure Pd of the hydraulic pump 1 is provided, and the regeneration operation and the regeneration cancellation are performed on the basis of the pump discharge pressure signal PD output from the pressure detector 29. Although the present invention is configured to perform the operation, the present invention is not limited to this, and for example, a pressure detector for detecting the load pressure is provided in the main pipeline located between the direction switching valve 20 and the hydraulic cylinder 2, and The regeneration operation and the regeneration cancellation operation may be performed based on the pressure signal output from the pressure detector.

In the above embodiment, the hydraulic cylinder 2 was used as an actuator for description, but a hydraulic motor may be provided instead of the hydraulic cylinder 2. Further, in the above description, the hydraulic excavator has been described as the hydraulic machine, but the present invention is not limited to such a hydraulic excavator and can be applied to a hydraulically operated crane or the like.

[0042]

Since the present invention is configured as described above, it is possible to easily realize the drive control of the actuator suitable for either the heavy load work or the light load work, which is difficult in the past. It is possible to improve the work efficiency of both heavy load work and light load work.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a hydraulic pressure regeneration device for a hydraulic machine corresponding to claims 1 to 7 of the present invention.

FIG. 2 is a diagram showing a configuration of a control device provided in the embodiment shown in FIG.

3 is a diagram showing a configuration of a storage unit and a calculation unit of the control device shown in FIG.

FIG. 4 is a diagram showing characteristics obtained in the embodiment shown in FIG.

FIG. 5 is a circuit diagram showing a conventional hydraulic pressure regeneration device for a hydraulic machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 hydraulic pump 2 hydraulic cylinder (actuator) 20 directional switching valve 21 check valve 23 tank side passage 24 communication passage 25 variable throttle (flow control means) 28 pump side passage 29 pressure detector (detection means) 30 tank 40 electromagnetic proportional pressure reducing valve (Driving means) 41 Work mode switch (instruction device) 44 Control device 61 Calculation unit 62 Storage unit 70 Pilot operated valve 100 Functional relation 101 Functional relation

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigehiro Yoshinaga 650 Jinrachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory (72) Inventor Koji Ishikawa 650 Kintate-cho, Tsuchiura-shi, Ibaraki Hitachi Machinery Company Tsuchiura Factory

Claims (7)

[Claims] 1. A hydraulic pump and a tank, an actuator driven by pressure oil discharged from the hydraulic pump, a direction switching valve controlling the flow of pressure oil supplied from the hydraulic pump to the actuator, and the actuator. To the tank, a tank-side passage that communicates with the tank, a flow rate control unit that controls the flow rate of the pressure oil introduced into the tank, a pump-side passage that connects the hydraulic pump and the actuator, and the pump-side passage and the A communication passage communicating with the tank-side passage, and when the pressure in the tank-side passage is higher than the pressure in the pump-side passage provided in the communication passage, pressure oil from the tank-side passage to the pump-side passage is A check valve for allowing the supply, a detection unit for detecting the pressure of the pressure oil supplied to the actuator, and a drive unit for the flow rate control unit. In the hydraulic regenerator of the hydraulic machine capable of regenerating the return oil from the actuator to the pump side passage through the communication passage, the pressure signal from the detecting means is input. A control device for outputting an actuation signal corresponding to the pressure signal to the drive means, the control device calculates a functional relationship between the pressure signal and a target value corresponding to the actuation signal in a predetermined heavy load work. And a storage unit that sets in advance a plurality of corresponding light load operations, and a calculation unit that calculates the corresponding target value based on the pressure signal and the functional relationship stored in the storage unit. Together with the predetermined heavy load work and a predetermined light load work, an instruction device capable of outputting an instruction signal corresponding to each of the control device, the arithmetic unit of the control device, In accordance with an instruction signal output from the instruction device, a corresponding functional relationship among the functional relationships corresponding to the predetermined heavy load work and the predetermined light load work stored in the storage unit. A hydraulic regeneration device for a hydraulic machine, characterized in that a calculation for obtaining a target value is performed based on the above. 2. The gain of the functional relationship between the pressure signal corresponding to the predetermined heavy load work and the target value stored in the storage unit is set to the pressure signal corresponding to the predetermined light load work and the gain. 2. The hydraulic pressure regenerating apparatus for a hydraulic machine according to claim 1, wherein the gain is set to be larger than the gain of the functional relationship with the target value. 3. The hydraulic regeneration device for a hydraulic machine according to claim 1, wherein the instruction device is a work mode switch. 4. The detection means is one of a pressure detector for detecting a discharge pressure of the hydraulic pump and a pressure detector for detecting a load pressure of the actuator. Hydraulic regenerator for hydraulic machines. 5. The hydraulic pressure regenerating apparatus for a hydraulic machine according to claim 1, wherein the flow rate control means is a variable throttle. 6. The hydraulic pressure regenerating apparatus for a hydraulic machine according to claim 1, wherein the drive means is an electromagnetic proportional pressure reducing valve. 7. The hydraulic regeneration device for a hydraulic machine according to claim 1, wherein the hydraulic machine is a hydraulic excavator.