CN217630210U - Bucket rod inward-retracting hydraulic system of positive-flow excavator - Google Patents

Abstract

The utility model relates to the technical field of engineering machinery, and discloses a bucket rod in-retraction hydraulic system of a positive-flow excavator, which comprises an oil tank, a first main pump, a second main pump, a bucket rod regeneration valve, a first bucket rod valve core, a second bucket rod valve core and a bucket rod oil cylinder; the second main pump is connected with a working oil inlet of the first bucket rod valve core, the first main pump is connected with a working oil inlet of the second bucket rod valve core, and a working oil outlet of the first bucket rod valve core is correspondingly connected with a working oil outlet of the second bucket rod valve core and then is connected with a bucket rod large cavity and a bucket rod small cavity corresponding to the bucket rod oil cylinder; the oil return port of the first bucket rod valve core is connected with the oil tank through a bucket rod regeneration valve, and the oil return port of the second bucket rod valve core is connected with the oil tank; and the second bucket rod valve core is a four-position valve and is used for performing sectional control on the bucket rod retraction action. The beneficial effects of the utility model are that: the bucket rod retraction action can have good operation performance and low oil consumption at the same time.

Description

Bucket rod inward-retracting hydraulic system of positive-flow excavator

Technical Field

The utility model relates to an engineering machine tool technical field relates to a positive flow excavator dipper adduction hydraulic system, concretely relates to automatically controlled positive flow hydraulic excavator dipper adduction hydraulic system.

Background

At present, excavators play a very critical role in construction projects. With the continuous increase of the excavator market, the requirement of customers on the control performance of the excavator is higher and higher, and energy conservation and environmental protection are necessary trends of the development of excavator technology. During the operation of the excavator, the arm not only provides most of the excavating force during the excavating action, but also plays an important role in the combined action of the excavator. If the operating performance of the bucket rod is improved, throttling is inevitably required to be added on a bucket rod working oil way, and the energy consumption is increased when the bucket rod is excavated due to the increased throttling, so that the technical difficulty that the operating performance and the system energy consumption of the bucket rod are considered is that of a hydraulic excavator.

In the prior art, a hydraulic system of a bucket rod part of a positive-flow hydraulic excavator mostly has two valve cores, namely a hydraulic control valve core and an electric control valve core, and the operation performance of the bucket rod adduction action is improved by controlling the opening degree of the electric control valve core, and the principle of the hydraulic system is mostly similar to that of fig. 1 and 2. The bucket rod regeneration function is mainly realized by adding a throttling valve on an oil return path of a main oil supply valve to establish oil return pressure, and adding a one-way valve between a small cavity and a large cavity of the bucket rod to ensure that hydraulic oil in the small cavity of the bucket rod can directly enter the large cavity of the bucket rod under the action of gravity, so that the aim of saving energy is fulfilled; meanwhile, the opening of the throttle valve on the oil return oil way is controlled by the pressure of the main oil supply pump of the bucket rod, when the bucket rod is high in pressure during excavation, the throttle valve can be fully opened, oil return backpressure is reduced, and the empty suction of the bucket rod is effectively reduced.

However, it is still difficult to control the arm while achieving both power consumption and operability.

In the prior art, the bucket rod regeneration system of the electric control positive flow excavator generally comprises the following two types:

the first type is that the bucket rod valve core 1 has an oil return path, and the bucket rod valve core 2 has no oil return path, as shown in fig. 1. When the excavator is operated to perform the arm retraction action, all the hydraulic oil returns from the arm valve core 1 to participate in regeneration. The scheme can ensure the operability of the inward contraction action of the bucket rod, but only one oil return circuit is arranged, so that large throttling loss is generated when the flow is large, the energy conservation is not facilitated, and the flow participating in regeneration is the whole flow of the inward contraction action of the bucket rod and cannot be adjusted. This approach may also cause repeated intervention and exit of the arm regeneration throttle, resulting in motion chatter.

The second type is that both valve cores of the bucket rod are provided with oil return passages, as shown in fig. 2. According to the scheme, the opening degree of the valve core 2 of the arm can be adjusted through the electromagnetic valve so as to optimize the operation performance of the inward contraction action of the arm. When a large load is met, the oil return path of the bucket rod valve core 2 can be controlled to be fully opened, throttling is reduced, and energy consumption is reduced. However, when the load is small, the opening degree of the arm valve body 2 needs to be reduced in order to optimize the operation performance of the arm, which may cause unnecessary meter-in. When the opening of the bucket rod valve core 2 is large, the opening of the oil return path of the bucket rod valve core 2 is large, and the regeneration effect of the bucket rod retraction action can be influenced.

In addition, chinese patent application CN113202952A discloses a method and a system for controlling a bucket arm regeneration valve of an excavator, wherein 2 bucket arm electromagnetic valves are provided, 1 is a three-position valve, and 1 is a four-position valve, as shown in fig. 3, the bucket arm electromagnetic valve can adapt to the working condition of the excavator and the engine speed, so as to ensure that the bucket arm electromagnetic valve can match the flow of the pump and the flow demand of the hydraulic cylinder in time, reduce the throttling loss, and improve the control performance of the bucket arm. However, there are the following disadvantages:

(1) When carrying out the dipper outward swing operation, the valve core can only make dipper solenoid valve 2 move to the B end in fig. 3, by the independent fuel feeding of pump 2, and dipper solenoid valve 1 no matter the displacement all can make the oil return oil circuit block up completely to which one end, and the hydraulic oil in the big chamber of dipper can't return the oil tank.

(2) When carrying out the dipper outward swing operation, the hydraulic oil in the big chamber of dipper, after the oil circuit of the B end of dipper solenoid valve 2, get back to the oil tank through the oil circuit of 1 meso position of dipper solenoid valve again, the oil return can receive the choke valve influence of 1 meso position of dipper solenoid valve always, causes the waste of energy.

(3) When carrying out the dipper adduction operation, dipper solenoid valve 1 does not have the oil return oil circuit, must have the cooperation of dipper solenoid valve 2 just can normally work, and dipper solenoid valve 1 shifts to the A end, and then dipper solenoid valve 2 must shift to A1 or A2 end, when carrying out the dipper adduction composite action, two spools are all opened, when the less dipper major cavity backpressure of load is low, can produce great influence to the composite action harmony.

(4) When the bucket rod is retracted under the heavy-load working condition, the bucket rod electromagnetic valve 1 and the bucket rod electromagnetic valve 2 are fully opened, the bucket rod electromagnetic valve 2 is located at the A2 position, hydraulic oil in a small cavity of the bucket rod completely returns to an oil tank through an oil return oil circuit of the bucket rod electromagnetic valve 2, the flow generated by the double pumps can be vented from a single pump, the throttling loss is large, and the double-pump hydraulic bucket rod is only suitable for medium-tonnage and small-tonnage machine types.

SUMMERY OF THE UTILITY MODEL

To prior art not enough, the utility model provides a hydraulic system is received in positive flow excavator dipper, makes the dipper adduction action possess good operating performance and lower oil consumption simultaneously.

In order to achieve the above object, the utility model provides a following technical scheme:

the utility model provides a bucket rod in-retraction hydraulic system of a positive-flow excavator, which comprises an oil tank, a first main pump, a second main pump, a bucket rod regeneration valve, a first bucket rod valve core, a second bucket rod valve core and a bucket rod oil cylinder; the second main pump is connected with a working oil inlet of the first bucket rod valve core, the first main pump is connected with a working oil inlet of the second bucket rod valve core, and a working oil outlet of the first bucket rod valve core is correspondingly connected with a working oil outlet of the second bucket rod valve core and then is connected with a bucket rod large cavity and a bucket rod small cavity corresponding to the bucket rod oil cylinder; the oil return port of the first bucket rod valve core is connected with the oil tank through a bucket rod regeneration valve, and the oil return port of the second bucket rod valve core is connected with the oil tank; the second bucket rod valve core is a four-position valve and is used for performing sectional control on the bucket rod retraction action, when the bucket rod valve core is in the first stage, the second bucket rod valve core is in a third working position, and no oil return path exists on the second bucket rod valve core; when the hydraulic system is in the second stage, the valve core of the second bucket rod is in the fourth working position, and the D port on the valve core of the second bucket rod is added to the oil return path of the hydraulic system.

Further, the second bucket rod valve core is an electric control valve core.

Further, when the excavator performs a light-load bucket rod retraction action, the first bucket rod valve core is displaced to a first working position from the left, hydraulic oil driven by a second main pump enters the bucket rod large cavity through the port A, the second bucket rod valve core is located at a third working position, namely the second bucket rod valve core is controlled at a first stage, the hydraulic oil driven by the first main pump enters the bucket rod large cavity through the port C, the second bucket rod valve core is not provided with an oil return path, and the hydraulic oil in the bucket rod small cavity returns to the oil tank through the port B on the first bucket rod valve core through the bucket rod regeneration valve; when the excavator carries out heavy-load bucket rod retraction, the first bucket rod valve core is still located at the first working position, the second bucket rod valve core is located at the fourth working position, namely the second bucket rod valve core is controlled at the second stage, the bucket rod regeneration valve receives pressure from the second main pump and displaces to the working position without throttling action, hydraulic oil driven by the first main pump enters the big cavity of the bucket rod through the opening E, an oil inlet oil way of the hydraulic system is unchanged relative to the first stage, and the oil return oil way is additionally provided with the opening D on the second bucket rod valve core.

It should be noted that: the light load and the heavy load are mainly judged by the pressure of the second main pump when the bucket rod is retracted. And when the pressure of the second main pump exceeds a certain threshold value, judging that the working condition is heavy load at the moment, otherwise, judging that the working condition is light load, wherein the threshold value is related to parameters such as the flow characteristic of the valve, the size of the arm cylinder and the like.

The first electromagnetic valve is arranged between the electric control end of the second bucket rod valve core and the pilot pump, the electric control end of the first electromagnetic valve is connected with the controller, and the controller controls the opening degree of the valve port of the second bucket rod valve core by controlling the first electromagnetic valve.

The second electromagnetic valve is arranged between a hydraulic control end of the bucket rod regeneration valve and a pump port of the pilot pump, an electric control end of the second electromagnetic valve is connected with the controller, and the controller controls the opening degree of a valve port of the bucket rod regeneration valve through the second electromagnetic valve.

Further, the first bucket rod valve core is a hydraulic control valve core and can also be an electric control valve core.

Compared with the prior art, the utility model provides a hydraulic system is received in positive flow excavator dipper stick possesses following beneficial effect:

(1) The utility model discloses a hydraulic system can be on the basis that does not change the main valve structure, through improving the structure that the automatically controlled case was received in the dipper, make the dipper adduction action can possess good operating performance and lower oil consumption simultaneously.

(2) The hydraulic system of the utility model can adapt to various working conditions simultaneously; the electronic control valve core is controlled in a first stage under the light-load working condition, so that the regeneration effect is enhanced, the energy consumption is reduced, and the suction of hopper rod adduction is reduced; under the heavy load working condition, the valve core is controlled at the second stage, so that throttling loss is reduced, and energy consumption is reduced. The operation performance of the arm retraction operation and the arm retraction combined operation is sufficiently excellent, and the energy consumed by the operation can be reduced.

(3) The utility model discloses a hydraulic system changes solenoid valve control through the control mode with dipper regenerative valve, can solve and solve the problem of inhaling sky when dipper adduction action starts to second main pump pressure fluctuation can not arouse the fluctuation of dipper regenerative valve, makes the excavator control more easily.

Drawings

FIG. 1 is a first schematic diagram of a prior art electric control positive flow excavator stick regeneration system;

FIG. 2 is a second schematic diagram of the operation of a bucket arm regeneration system of an electrically controlled positive flow excavator in the prior art;

FIG. 3 is a schematic diagram of a prior art solenoid valve of the present invention patent application (publication No. CN 113202952A);

fig. 4 is a schematic diagram of a hydraulic system for retracting the bucket rod in embodiment 1 of the present invention;

fig. 5 is a schematic diagram of a hydraulic system for retracting the bucket rod in embodiment 2 of the present invention.

The reference numerals in the figures have the meaning:

1-a first main pump, 2-a second main pump, 3-an oil tank, 4-a bucket rod regeneration valve, 5-a first bucket rod valve core, 6-a second bucket rod valve core, 7-a bucket rod large cavity, 8-a bucket rod small cavity, 9-a first electromagnetic valve and 10-a second electromagnetic valve.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Unless specifically stated otherwise, the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may also include different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present application, it is to be understood that the terms "central," "longitudinal," "lateral," "up," "down," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings for convenience in describing the invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be considered as limiting the scope of the invention.

As shown in fig. 4, the bucket rod adduction hydraulic system of the present invention includes an oil tank 3, a first main pump 1, a second main pump 2, a bucket rod regeneration valve 4, a first bucket rod valve core 5, a second bucket rod valve core 6, and a bucket rod oil cylinder; the second main pump 2 is connected with a working oil inlet of the first bucket rod valve core 5, the first main pump 1 is connected with a working oil inlet of the second bucket rod valve core 6, and a working oil outlet of the first bucket rod valve core 5 is correspondingly connected with a working oil outlet of the second bucket rod valve core 6, converged and then connected with a bucket rod large cavity 7 and a bucket rod small cavity 8 which correspond to the bucket rod oil cylinder; an oil return port of the first bucket rod valve core 5 is connected with the oil tank 3 through the bucket rod regeneration valve 4, and an oil return port of the second bucket rod valve core 6 is connected with the oil tank 3; the second bucket rod valve core 6 is a four-position valve and is used for performing segmented control on the bucket rod retraction action, when the bucket rod is in the first stage, the second bucket rod valve core 6 is in a third working position, and no oil return line is arranged on the second bucket rod valve core 6; when the second stage is performed, the second arm valve core 6 is in the fourth working position, and a D port on the second arm valve core 6 is added to an oil return path of the hydraulic system.

In a specific embodiment of the present embodiment, the second arm valve element 6 is an electrically controlled valve element.

In a specific embodiment of this embodiment, when the excavator performs a light-load boom retraction operation, the first boom spool 5 is displaced to the left to serve as a first working position, hydraulic oil driven by the second main pump 2 enters the boom large cavity 7 through the port a, the second boom spool 6 is in a third working position (the third working position is a third working position counted from left to right in fig. 4), that is, the second boom spool 6 is controlled in a first stage, hydraulic oil driven by the first main pump 1 enters the boom large cavity 7 through the port C, the second boom spool 6 has no oil return path, hydraulic oil in the boom small cavity 8 returns to the oil tank 3 through the port B on the first boom spool 5 and the boom regeneration valve 4, during oil return, due to the throttling function of the boom regeneration valve 4, hydraulic oil at the port B of the boom regeneration valve 4 establishes a certain pressure, and thus directly enters the boom large cavity 7 through the check valve between the ports a and B, so that all hydraulic oil participates in regeneration, energy is effectively saved, and a null suction prevention function is achieved.

When the excavator performs a heavy-duty bucket rod retraction action, the first bucket rod valve core 5 is still at a first working position (the first working position is the first working position counted from left to right in fig. 4)), the second bucket rod valve core 6 is at a fourth working position (the fourth working position is the fourth working position counted from left to right in fig. 4), that is, the second bucket rod valve core 6 is controlled at a second stage, the bucket rod regeneration valve 4 receives pressure from the second main pump 2 and displaces to a working position without throttling action, and at this time, the bucket rod regeneration valve 4 does not play a throttling action any more; hydraulic oil driven by the first main pump 1 enters the big cavity 7 of the bucket rod through the opening E, an oil inlet path of the hydraulic system is unchanged relative to the first stage, and an oil return path is additionally provided with an opening D on the valve core 6 of the second bucket rod, so that oil return backpressure is reduced.

In a specific implementation manner of this embodiment, the hydraulic control device further includes a first electromagnetic valve 9, and the first electromagnetic valve 9 is disposed at the electric control end of the second arm valve core 6.

In a specific embodiment of this embodiment, the first electromagnetic valve 9 is disposed between the electric control end of the second arm valve spool 6 and a pilot pump (the pilot pump is not shown in fig. 4 and 5), the electric control end of the first electromagnetic valve 9 is connected to a controller (not shown in fig. 4 and 5), and the controller controls the opening degree of the valve port of the second arm valve spool 6 by controlling the first electromagnetic valve 9.

The utility model discloses bucket rod adduction hydraulic system's control method does:

the method comprises the following steps: when the bucket rod is retracted, the pilot pressure of the retraction action of the bucket rod is collected, and the displacement of the operating handle corresponding to the pilot pressure is calculated.

Step two: the upper limit value k1 of the opening degree of the second arm valve element 6 is calculated according to the displacement of the operating handle.

Step three: the pressure of the second main pump 2 is collected, the state of the arm regeneration valve 4 is determined, and the opening k2 of the arm regeneration valve 4 corresponding to the pressure of the second main pump 2 is calculated.

If k2 is smaller than a threshold p3 preset by the system (the value can be directly obtained according to the characteristic parameters of the arm regeneration valve 4), the second arm valve core 6 is controlled at a first stage (a third working position) by using the first electromagnetic valve 9, so that all the working oil in the arm small cavity 8 returns from the first arm valve core 5, the regeneration action of the arm is in a strongest state, and the energy consumption is reduced; if k2 is larger than a preset threshold p3 of the system, the second arm valve core 6 is controlled at a second stage (a fourth working position), that is, an oil return path of the second arm valve core 6 is properly released, oil return backpressure is reduced, the opening degree of the second arm valve core 6 and the opening degree of the arm regeneration valve 4 are adapted to each other, a hydraulic system of the arm part is in a state most suitable for the current working condition, the operation performance of the whole machine is ensured, and energy consumption is reduced.

Step four: the variable k2 is processed according to the threshold p3, so that the opening k3 of the arm valve 2 corresponding to the main pump pressure can be obtained.

Step five: a small value is taken between the two variables k1 and k3, and the small value is a target opening degree of the second arm valve element 6, and the input current of the corresponding first electromagnetic valve 9 is calculated according to the target opening degree, so that the control function of the arm adduction action is realized.

The utility model discloses a theory of operation does:

an electric control valve core (a second bucket rod valve core 6) for the inward closing action of the bucket rod is divided into two sections for control: in the first stage, the opening of the oil inlet circuit of the valve core is increased from 0 to the maximum along with the increase of the current of the electromagnetic valve, and the opening of the oil return circuit is always 0; the current of the electromagnetic valve at the second stage continuously increases the opening degree of the oil inlet path of the valve core to be maximum all the time, and the opening degree of the oil return path is also increased from 0 to be maximum, as shown in a second bucket rod valve core 6 of fig. 4.

When the excavator performs the light-load bucket rod retraction action, the second bucket rod valve core 6 can be controlled in the first stage, namely the oil return oil path of the second bucket rod valve core 6 is closed, the operation performance of the bucket rod retraction action and the bucket rod retraction composite action is optimized by adjusting the opening degree of the inlet of the second bucket rod valve core 6, at the moment, all hydraulic oil of the bucket rod retraction action returns from the first bucket rod valve core 5, and therefore the regeneration effect is not influenced.

When the excavator performs the heavy-load bucket rod adduction action, the second bucket rod valve core 6 can be controlled at the second stage, the opening degree of the oil return oil way of the second bucket rod valve core 6 required by working pressure is calculated, the bucket rod adduction is always in the working state most suitable for the current working condition, the operation performance of the whole excavator is guaranteed, and the energy consumption is reduced to the maximum degree.

Example 2

Because the hydraulic shock is generated by the in-arm hydraulic system in the embodiment 1, the pressure of the second main pump 2 generates an instantaneous peak value, and the peak value can generate unexpected displacement of the arm regeneration valve 4, which can cause suction during the no-load starting of the in-arm action; when the pressure is reduced, the bucket rod regeneration valve 4 returns to the original position, the retraction speed in the bucket rod is reduced, the action speed is changed in a nonlinear mode, and the operation experience of a driver is influenced. In addition, when the excavator performs some actions (for example, when a mine site performs regular or digging-loading on a large stone, load fluctuation is large, soil loosening is leveled by combined actions of bucket rod retraction and boom raising, and other actions suddenly intervene when bucket rod retraction is performed), the pressure of the second main pump 2 fluctuates, so that the bucket rod regeneration valve 4 is unstable, pressure fluctuation is further caused, and controllability is affected.

In order to solve the above problem, the bucket rod adduction hydraulic system in this embodiment changes the control mode of bucket rod regeneration valve 4 into electromagnetic valve control, as shown in fig. 5 (pilot pump and controller are not shown in the figure), the utility model discloses a bucket rod adduction hydraulic system still includes second electromagnetic valve 10, and second electromagnetic valve 10 is connected with bucket rod regeneration valve 4, and second electromagnetic valve 10 sets up between the hydraulic control end of bucket rod regeneration valve 4 and the pump mouth of pilot pump, and the automatically controlled end of second electromagnetic valve 10 is connected with the controller, and the valve port aperture of bucket rod regeneration valve 4 is controlled through second electromagnetic valve 10 to the controller.

The instantaneous peak value of the pressure of the second main pump 2 is identified through the controller, and the control is distinguished from other conditions (other conditions refer to the condition that the pressure of the second main pump 2 does not generate the instantaneous peak value in the process of the inside contraction operation of the arm), so that the problem of suction during the start of the inside contraction operation of the arm is solved, the fluctuation of the pressure of the second main pump 2 cannot cause the fluctuation of the regeneration valve 4 of the arm, and the excavator is easier to control.

In a specific embodiment of the present embodiment, the first bucket rod valve core 5 is a hydraulic control valve core.

It is noted that, in the present application, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (6)

1. The utility model provides a hydraulic system is received in positive flow excavator dipper stick which characterized in that: the hydraulic control system comprises an oil tank, a first main pump, a second main pump, a bucket rod regeneration valve, a first bucket rod valve core, a second bucket rod valve core and a bucket rod oil cylinder; the second main pump is connected with a working oil inlet of the first bucket rod valve core, the first main pump is connected with a working oil inlet of the second bucket rod valve core, and a working oil outlet of the first bucket rod valve core is connected with a working oil outlet of the second bucket rod valve core correspondingly, and then is connected with a bucket rod large cavity and a bucket rod small cavity corresponding to the bucket rod oil cylinder after being converged; the oil return port of the first bucket rod valve core is connected with the oil tank through a bucket rod regeneration valve, and the oil return port of the second bucket rod valve core is connected with the oil tank; the second bucket rod valve core is a four-position valve and is used for performing segmented control on the inward contraction action of the bucket rod, when the bucket rod is in the first stage, the second bucket rod valve core is in a third working position, and no oil return path exists on the second bucket rod valve core; when the hydraulic system is in the second stage, the valve core of the second bucket rod is in the fourth working position, and the D port on the valve core of the second bucket rod is added to the oil return path of the hydraulic system.

2. The positive flow excavator stick in-take hydraulic system of claim 1, wherein: the second bucket rod valve core is an electric control valve core.

3. The positive flow excavator stick in-take hydraulic system of claim 1 or 2, wherein: when the excavator performs a light-load bucket rod retraction action, the first bucket rod valve core is displaced to a first working position from the left, hydraulic oil driven by a second main pump enters the bucket rod large cavity through an opening A, the second bucket rod valve core is in a third working position, namely the second bucket rod valve core is controlled at a first stage, the hydraulic oil driven by the first main pump enters the bucket rod large cavity through an opening C, the second bucket rod valve core has no oil return path, and the hydraulic oil in the bucket rod small cavity returns to an oil tank through a bucket rod regeneration valve through an opening B on the first bucket rod valve core; when the excavator carries out heavy-load bucket rod retraction, the first bucket rod valve core is still located at the first working position, the second bucket rod valve core is located at the fourth working position, namely the second bucket rod valve core is controlled at the second stage, the bucket rod regeneration valve receives pressure from the second main pump and displaces to the working position without throttling action, hydraulic oil driven by the first main pump enters the big cavity of the bucket rod through the opening E, an oil inlet oil way of the hydraulic system is unchanged relative to the first stage, and the oil return oil way is additionally provided with the opening D on the second bucket rod valve core.

4. The positive flow excavator stick in-take hydraulic system of claim 1, wherein: the first electromagnetic valve is arranged at the electric control end of the second bucket rod valve core.

5. The positive flow excavator stick in-take hydraulic system of claim 1, wherein: the hydraulic control system further comprises a second electromagnetic valve, the second electromagnetic valve is connected with the bucket rod regeneration valve, the second electromagnetic valve is arranged between the hydraulic control end of the bucket rod regeneration valve and the pump opening of the pilot pump, and the electric control end of the second electromagnetic valve is connected with the controller.

6. The positive flow excavator stick in-take hydraulic system of claim 1, wherein: the first bucket rod valve core is a hydraulic control valve core or an electric control valve core.

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