JP3961123B2 - Hydraulic circuit of hydraulic work machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic circuit in which hydraulic oil discharged from two hydraulic pumps is combined as needed in a hydraulic working machine such as a hydraulic excavator and supplied to a hydraulic actuator that requires a large flow rate.
[0002]
[Prior art]
The conventional combined hydraulic circuit and its problems will be described taking a hydraulic excavator as an example of the present invention as an example.
[0003]
In the case of a hydraulic excavator, as hydraulic actuators, hydraulic cylinders (first and second boom cylinders, first and second both arm cylinders, bucket cylinders) that respectively drive booms, arms, and buckets that constitute the excavation attachment, and swing Hydraulic motors and left and right traveling hydraulic motors are used.
[0004]
This group of actuators is divided into two groups, and the actuators in both groups are basically driven by separate hydraulic pumps.
[0005]
For example,
First group: Left travel motor, first boom cylinder, second arm cylinder, bucket cylinder Second group: Right travel motor, first arm cylinder, second boom cylinder, swivel motor, the first group is the first hydraulic pump Thus, the second group is driven by the second hydraulic pump, respectively.
[0006]
Also, in the hydraulic excavator, when it is necessary to perform excavation / soil removal action by the bucket at high speed, the discharge oil of the second hydraulic pump is merged with the discharge oil of the first hydraulic pump and supplied to the bucket cylinder. The cylinder can be operated at a high speed.
[0007]
The hydraulic circuit configuration of such a hydraulic excavator will be specifically described with reference to FIG.
[0008]
In the figure, illustration of actuators other than the bucket cylinder Bc to which the combined oil is supplied is omitted, and only a control valve for individually controlling these operations is shown.
[0009]
Reference numeral 1 denotes a variable displacement type first hydraulic pump. A hydraulic pilot type confluence switching valve 2 is provided in the discharge line of the first hydraulic pump 1, and one outlet port of the confluence switching valve 2 leads to a tank T. A center bypass line 3 is connected.
[0010]
On the center bypass line 3, for the left traveling motor, the first boom cylinder, the second arm cylinder, and the bucket cylinder Bc that are individually operated by a remote control valve (not shown) in order from the upstream side (the lower side in the figure). The hydraulic pilot type control valves 4, 5, 6, and 7 are provided, and a hydraulic pilot type cut valve 8 is provided on the most downstream side.
[0011]
Further, a negative control throttle 9 as a negative control means is provided further downstream of the cut valve 8, and an inlet pressure (hereinafter referred to as negative control pressure) Pn 1 of the negative control throttle 9 passes through the negative control line 10 and is a regulator of the first hydraulic pump 1. The pump 1 is negatively controlled by being guided to 1a.
[0012]
That is, if the negative control pressure Pn1 is low, the tank flow rate (the flow rate returning to the tank T through the negative control throttle 9) is small and the pump discharge amount is increased if the actuator required flow rate is high. Control is performed to reduce the pump discharge amount, assuming that the required flow rate of the actuator is small.
[0013]
An oil supply line 11 is connected to the other outlet port of the merging switching valve 2, and its tip is connected to the bypass line 3 on the inlet side of the cut valve 8, and the first boom cylinder is connected to the oil supply line 11. Branch pipes 12, 13, 14 for supplying oil to the control valves 5, 6, 7 for the second boom cylinder and the bucket cylinder are connected to the downstream side of the control valve 4 for the left travel motor. Thus, the center bypass line 3 and the oil supply line 11 are connected by a merging pipeline 15. Reference numeral 16 denotes a first group relief valve provided in the oil supply line 11.
[0014]
On the other hand, the basic circuit of the second group is the same as that of the first group.
[0015]
That is, a center bypass line 18 is connected to the discharge line of the variable displacement type second hydraulic pump 17, and on the center bypass line 18, in order from the upstream side, for a right traveling motor operated by a remote control valve (not shown), Hydraulic pilot type control valves 19, 20, 21, and 22 for the first arm cylinder, the second boom cylinder, and the swing motor are provided, and the bypass line 18 communicates with the tank T on the most downstream side. There is provided a hydraulic pilot type cut valve 23 that switches between a merging release position a to be performed and a merging position b to be blocked with respect to the tank T.
[0016]
Further, a negative control throttle 24 is provided further downstream of the cut valve 23, and the inlet pressure (negative control pressure) Pn2 of the negative control throttle 24 is led to the regulator 17a of the second hydraulic pump 17 through the negative control line 25, thereby The pump 17 is negatively controlled like the first hydraulic pump 1.
[0017]
An oil supply line 26 is connected in parallel to the center bypass line 18 so as to short-circuit the downstream side of the right travel motor control valve 19 and the upstream side of the cut valve 23. From the oil supply line 26, the first boom cylinder is connected. Branch pipes 27, 28, 29 for supplying oil are connected to each of the control valves 20, 21, 22 for the second arm cylinder and the swing motor. Reference numeral 30 denotes a relief valve for the second group provided in the oil supply line 26.
[0018]
A junction line 31 is branched and connected to the discharge line of the second hydraulic pump 17 on the upstream side of the right travel motor control valve 20, and this junction line 31 is connected to one inlet port of the junction switching valve 2. Has been.
[0019]
The merge switching valve 2 has a merge release (single flow) position a and a merge position b, and only the discharge oil of the first hydraulic pump 1 is supplied to the center bypass line 3 at the merge release position a in the figure.
[0020]
A remote control pressure Pb from a bucket remote control valve (not shown) that operates the control valve 7 for the bucket cylinder Bc is sent to the pilot port of the control valve 7 through the pilot line 32 or 33 to switch the control valve 7.
[0021]
The remote control pressure Pb is applied to the pilot port of the hydraulic pilot-type hydro valve 35 via the shuttle valve 34 at the time of merging (may be always during operation or only at the time of merging operation by an operator's switch operation or the like). The hydro valve 35 is switched from the merging release position a to the merging position b.
[0022]
Then, the pilot pressure Pi is sent to the pilot ports of the merging switching valve 2 and the second group cutting valve 23 through the hydro valve 35, the merging switching valve pilot line 36, and the cut valve pilot line 37. and the cut valve 2 3 is switched to the respective merge position b.
[0023]
As a result, as shown by a broken line in FIG. 7, the discharge oil of the second hydraulic pump 17 passes through the merging line 31, the merging switching valve 2, the center bypass line 3, and the merging pipeline 15 at the merging point K at the first hydraulic pump. 1 is supplied to the bucket cylinder Bc via the bucket cylinder control valve 7, and the bucket operates at high speed.
[0024]
The hydro valve 35 also has a pilot port on the opposite side, and during the merging, at least one of the control valves 20, 21, 22 except for the control valve 19 for the right traveling motor of the second group (boom, arm or When (turning) is operated, the merging action is stopped by returning to the merging release position a by the remote control pressure Pa or Pt. This ensures the operation of the second group of actuators.
[0025]
[Problems to be solved by the invention]
However, according to the conventional hydraulic circuit configuration, the maximum discharge amount of the second hydraulic pump 17 is always merged with the discharge oil of the first hydraulic pump 1 at the time of merging. In some cases, the flow rate becomes excessive and the operation of the bucket becomes too fast.
[0026]
Therefore, the present invention provides a hydraulic circuit of a hydraulic working machine that can control the amount of combined oil to an appropriate amount and improve the operability of an actuator supplied with the combined oil.
[0027]
[Means for Solving the Problems]
In the first aspect of the invention, the hydraulic actuators are divided into first and second groups, the first group is driven by the first hydraulic pump, the second group is driven by the second hydraulic pump, and the merging position The merging control valve that switches between the merging release position and the merging release position is switched to the merging position based on the merging command signal so that the discharge oil of the second hydraulic pump merges with the discharge oil of the first hydraulic pump, and The hydraulic circuit of the hydraulic working machine configured to supply a specific hydraulic actuator in the first group includes a merging control unit, and the merging control unit sets a command speed for the specific hydraulic actuator during the merging. Accordingly, the merging oil amount is controlled to increase as the command speed increases, and the hydraulic actuators in the second group are operated during merging. Are those that are configured to release the confluence switching the confluence control valve to merge release position when the.
[0028]
According to a second aspect of the present invention, in the configuration of the first aspect, a hydraulic pilot type switching valve is used as the merging control valve, the merging control means detects command speed detecting means for detecting a command speed for the specific hydraulic actuator, and the command speed. The controller includes a controller that outputs a signal corresponding to the command speed detected by the detecting means, and an electromagnetic proportional valve that controls the merging control valve in accordance with the output signal of the controller .
[0029]
According to a third aspect of the present invention, in the configuration of the first or second aspect, the merging control valve is joined to the merging line for merging the discharged oils of the first and second hydraulic pumps based on the control signal from the merging control means. A merging switching valve that switches between a position and a merging release position is provided, and a bypass line is provided at the most downstream side of the bypass line that is provided through a control valve that individually controls each hydraulic actuator of the second group. A cut valve that switches between a merge release position that communicates with the tank and a merge position that shuts off the tank is provided, and at the time of merge, the merge control valve and the cut valve are respectively moved toward the merge position by the merge control means. And the opening degree of at least one of the merge switching valve and the cut valve at this time is controlled .
[0030]
According to a fourth aspect of the present invention, in the configuration according to any one of the first to third aspects, variable displacement pumps are used as the first and second hydraulic pumps, and the discharge oil amount of both the hydraulic pumps is automatically controlled by the negative control means. it is configured to be controlled, merging control means, when confluent, in which are configured to obtain so that by controlling the discharge oil amount of the second hydraulic pump in place of the negative control unit.
[0031]
According to the above configuration, at the time of merging, the merging control means controls the merging oil amount of the discharge oil of the second hydraulic pump according to the command speed for the specific actuator (actuator supplied with the merging oil). However, the higher the command speed, the lower the speed, and the lower the command speed. Therefore, the speed change of the specific actuator is adapted to the operator's request.
[0032]
For this reason, the actuator can be operated at an appropriate speed by setting the above merging control characteristics according to the machine or according to the type of work, the operator's preference, etc., and has good operability. Doo ing.
[0033]
In addition, when the actuators in the second group are operated during the merging, the merging is canceled and the operation of the actuators in the second group can be guaranteed.
[0034]
In this case, according to the configuration of 請 Motomeko 3, the confluence switching valve and the cut valve is used as the confluence control valve, merging oil amount by which these at least one opening is controlled at the confluence it is controlled.
[0035]
On the other hand, according to the configuration of the fourth aspect, in the hydraulic circuit adopting the negative control method, the merged oil amount is controlled by controlling the discharge amount of the second hydraulic pump at the time of merging .
[0036]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
[0037]
1st Embodiment (refer FIGS. 1-3)
In the first embodiment, the same parts as those in the conventional circuit shown in FIG.
[0038]
When a bucket remote control valve (not shown) that controls the control valve 7 for the bucket cylinder Bc is operated, a remote control pressure (hereinafter referred to as bucket remote control pressure) Pb proportional to the lever operation amount is connected to the shuttle valve 34. It is detected by a pressure sensor (command speed detection means) 38 and output to a controller 39 constituting the merging control means (see FIG. 2).
[0039]
Then, a signal having a magnitude proportional to the detected remote control pressure Pb is sent from the controller 39 to the electromagnetic proportional valve 40 (see FIG. 3).
[0040]
Then, the proportional valve 40 opens at an opening degree corresponding to the bucket remote control pressure Pb, and the secondary pressure corresponding to the opening degree passes through the merging switching valve pilot line 41 and the cut valve pilot line 42 and the merging switching valve 2 and the second pressure. By being sent to each pilot port of the cut valve 23 for the two groups, the merging switching valve 2 and the cut valve 23 are respectively operated with strokes according to the input signal toward the merging position b.
[0041]
As a result, the oil discharged from the second hydraulic pump 17 passes through the merging line 31, the merging switching valve 2, the center bypass line 3, and the merging pipe line 15 and merges with the oil discharged from the first hydraulic pump 1 at the merging point K. The bucket is supplied to the bucket cylinder Bc via the cylinder control valve 7 and the bucket operates at high speed.
[0042]
In this case, as described above, the discharge of the second hydraulic pump 17 is performed only when the merging switching valve 2 and the cut valve 23 are stroke-operated by an amount corresponding to the operation amount of the bucket remote control valve and the bucket remote control valve is fully operated. The total amount joins the discharge amount of the first hydraulic pump 1.
[0043]
In other words, the amount of merging oil from the second hydraulic pump 17 is reduced by the cut valve 23 and the merging switching valve 2 except when the remote control valve is fully operated.
[0044]
For this reason, as in the case where the total discharge amount of the second hydraulic pump 17 always joins at the time of merging, depending on the machine, the type of work, the operator's preference, etc., the merging oil amount is too much and the bucket operation is quick. There is no risk of becoming too much.
[0045]
In addition, the combined oil amount is controlled according to the bucket remote control pressure Pb, that is, the bucket command speed by the operator, and increases as the command speed increases and decreases as the command speed decreases. It will be adapted to the requirements. For this reason, operability is further improved.
[0046]
When at least one of the control valves 20, 21, 22 except the control valve 19 for the right traveling motor of the second group is operated during the merging, the remote control pressure Pa or Pt Is input to the controller 39, the signal output to the electromagnetic proportional valve 40 is stopped, and the arm or the turning operation is performed without any trouble.
[0047]
2nd Embodiment (refer FIGS. 4-6)
Only differences from the first embodiment will be described.
[0048]
In 2nd Embodiment, the structure which can control the discharge amount of the 2nd hydraulic pump 17 at the time of merge is taken.
[0049]
In the case of this second embodiment, the confluence switching valve 2 and the second group of cut valves 23 are not the opening control as in the case of the first embodiment, but the position control that switches completely between both positions a and b. Is done.
[0050]
In addition to this position control, that is, the electromagnetic proportional valve 40 for switching the merging switching valve 2 and the cut valve 23 to the merging position b at the time of merging, the electromagnetic proportional valve 43 for controlling the second hydraulic pump (hereinafter referred to as the first A proportional valve, the latter being referred to as a second proportional valve), and an output signal from the controller 39 is sent to both proportional valves 40 and 43 simultaneously.
[0051]
As shown in FIG. 5, the second proportional valve 43 has a characteristic such that the secondary pressure Pc changes in inverse proportion to the controller output (lever operation amount), that is, the secondary pressure increases as the controller output decreases. Is set.
[0052]
The secondary pressure Pc of the second proportional valve 43 is led to the second hydraulic pump control line 44, and the high pressure side of the secondary pressure Pc and the negative control pressure Pn 2 guided to the negative control line 25 is set by the shuttle valve 45. The pump 17 is controlled by being introduced into a regulator 17 a of the hydraulic pump 17.
[0053]
Therefore, the secondary pressure Pc of the second proportional valve 43 is introduced into the regulator 17a at the time of merging.
[0054]
Here, the secondary pressure Pc is inversely proportional to the lever operation amount (bucket remote control pressure Pb). If the lever operation amount is small, the secondary pressure Pc is high and the discharge amount of the second hydraulic pump 17 is small. As the flow increases, the pump discharge rate increases.
[0055]
In FIG. 6, Pc1 represents the proportional valve secondary pressure when the lever operation amount is maximum (full lever), and Pc2 represents the proportional valve secondary pressure when the lever operation amount is minimum (neutral lever).
[0056]
By controlling the discharge amount of the second hydraulic pump 17 as described above, the total flow rate of the first group at the time of merging can be controlled to an appropriate amount.
[0057]
As shown by the broken line in FIG. 5, the proportional valve secondary pressure Pc is set so as not to decrease below a certain value with respect to the controller output (lever operation amount), and as a result, as shown by the broken line in FIG. The characteristics may be set to limit the maximum discharge amount of the two hydraulic pumps 17.
[0058]
Moreover, in 2nd Embodiment, the structure which performs discharge amount control of the 2nd hydraulic pump 17 may be taken, utilizing the effect | action (opening control effect | action of the merging switching valve 2 and the cut valve 23) of 1st Embodiment.
[0059]
Furthermore, in 1st Embodiment, the structure which controls the opening degree about only one of the confluence | merging switching valve 2 and the cut valve 23 may be taken.
[0060]
【The invention's effect】
As described above, according to the present invention, at the time of merging, the merging control means controls the amount of merging oil discharged from the second hydraulic pump according to the command speed for the specific actuator (actuator supplied with the merging oil). Since the combined oil amount increases as the command speed increases and decreases as the command speed decreases, the change in the speed of the specific actuator is adapted to the operator's request.
[0061]
For this reason, the actuator can be operated at an appropriate speed by setting the above merging control characteristics according to the machine or according to the type of work, the operator's preference, etc., and has good operability. Doo ing.
[0062]
In addition, when the actuators in the second group are operated during merging, the merging is canceled and the operation of the actuators in the second group can be guaranteed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a hydraulic circuit according to a first embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between bucket remote control pressure and pressure sensor output in the first embodiment.
FIG. 3 is a diagram illustrating a relationship between a controller input and a controller output in the first embodiment.
FIG. 4 is a diagram showing a hydraulic circuit according to a second embodiment of the present invention.
FIG. 5 is a diagram illustrating a relationship between a controller output and a proportional valve secondary pressure in the second embodiment.
FIG. 6 is a diagram illustrating a relationship between a proportional valve secondary pressure and a discharge amount of a second hydraulic pump in the second embodiment.
FIG. 7 is a diagram showing a conventional hydraulic circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st hydraulic pump 17 2nd hydraulic pump Bc Bucket cylinder as a specific actuator 7 Control valve for bucket cylinder control 4, 5, 6 Control valve for other actuator control of 1st group 3 Bypass line 19 of 1st group , 20, 21, 22 Control valve for controlling each actuator of the second group 18 Bypass line of the second group 2 Hydraulic pilot type merging switching valve as the merging control valve 23 Hydraulic pilot type cutting of the second group as the merging control valve Valve 38 Pressure sensor as command speed detecting means 39 Controller constituting merging control means 40 Electromagnetic proportional valve constituting merging control means 43 Electromagnetic proportional valve for controlling second hydraulic pump constituting merging control means 9, 24 Negative control As a means Negative control aperture

Claims (4)

The plurality of hydraulic actuators are divided into both first and second groups, the first group is driven by the first hydraulic pump, the second group is driven by the second hydraulic pump, and the merging position and the merging release position are The merging control valve that switches between them is switched to the merging position based on the merging command signal, so that the discharge oil of the second hydraulic pump is merged with the discharge oil of the first hydraulic pump, and the specified in the first group The hydraulic circuit of the hydraulic working machine configured to supply the hydraulic actuator includes a merging control unit, and the merging control unit is configured to perform the merging oil according to a command speed for the specific hydraulic actuator during the merging. The amount is controlled to increase as the command speed increases, and the hydraulic actuator in the second group is operated during merging. Hydraulic working machine of a hydraulic circuit, characterized in that it is configured to cancel the confluence switching the confluence control valve to merge release position. 2. The hydraulic circuit of the hydraulic working machine according to claim 1, wherein a hydraulic pilot type switching valve is used as the merging control valve, the merging control means detects command speed for the specific hydraulic actuator, and the command speed detection. A hydraulic circuit for a hydraulic working machine, comprising: a controller that outputs a signal according to a command speed detected by the means; and an electromagnetic proportional valve that controls a merging control valve according to the output signal of the controller . The hydraulic circuit of the hydraulic working machine according to claim 1 or 2 , wherein the merging position is a merging position based on a control signal from the merging control means, as a merging control valve , to a merging line for merging the discharged oils of the first and second hydraulic pumps. And a merging switching valve that switches between a merging release position and a merging release position, and a bypass line is tanked at the most downstream of the bypass line that is provided through the control valve that individually controls each hydraulic actuator of the second group. A cut valve that switches between a merge release position that communicates with the tank and a merge position that shuts off from the tank is provided, and at the time of merge, the merge control valve and the cut valve are moved toward the merge position by the merge control means, respectively. actuated, and at least one opening of the confluence switching valve and the cut valve at this time is configured to be controlled oil Hydraulic circuit of the work machine. 4. The hydraulic circuit for a hydraulic working machine according to claim 1, wherein variable displacement pumps are used as both the first and second hydraulic pumps, and the discharge oil amount of both hydraulic pumps is automatically controlled by a negative control means. is configured to be controlled, merging control means, when confluent, the hydraulic working machine, characterized in that it is configured to control to obtain so that the discharge oil amount of the second hydraulic pump in place of the negative control means Hydraulic circuit .

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