阅读说明：本技术 负载敏感泵系统、液压控制系统和工程机械 (Load-sensitive pump system, hydraulic control system and engineering machinery ) 是由 向小强 刘东宏 仝猛 王建成 陈龙 于 2020-05-11 设计创作，主要内容包括：本公开涉及一种负载敏感泵系统、液压控制系统和工程机械。其中,负载敏感泵系统包括：变量泵；定量泵,与变量泵由同一驱动机构驱动；变量控制机构,用于控制变量泵；控制油路；以及取压阀,被配置为通过控制油路将定量泵的部分输出压力作用于变量控制机构的控制端,以在驱动机构的驱动转速升高时增大变量泵的最大排量。通过设置取压阀,取压阀将定量泵的部分压力变化信号引入变量控制机构的控制端,使得驱动机构的驱动转速升高时变量控制机构能够增大变量泵的最大排量,本公开负载敏感泵系统无需额外增加电气控制器或线束之类,通过自身液控油路,实现了功率随转速可变控制的效果,具有较高的可实施性。(The disclosure relates to a load-sensitive pump system, a hydraulic control system and an engineering machine. Wherein, load-sensitive pump system includes: a variable displacement pump; the constant delivery pump and the variable delivery pump are driven by the same driving mechanism; a variable control mechanism for controlling the variable pump; controlling an oil path; and a pressure-taking valve configured to apply a part of the output pressure of the fixed displacement pump to a control end of the variable-displacement control mechanism through the control oil passage to increase the maximum displacement of the variable-displacement pump when the driving rotation speed of the driving mechanism increases. Through setting up the pressure taking valve, the pressure taking valve introduces the partial pressure change signal of constant delivery pump into variable control mechanism's control end for drive mechanism's driving speed rises time variable control mechanism can increase the maximum discharge capacity of variable delivery pump, and this disclosed load sensitive pump system need not additionally to increase electric controller or pencil class, through self liquid accuse oil circuit, has realized the effect of power along with the variable control of rotational speed, has higher enforceability.)

1. A load sensitive pump system, comprising:

a variable displacement pump (1);

the constant delivery pump (2) and the variable delivery pump (1) are driven by the same driving mechanism;

a variable control mechanism for controlling the variable pump (1);

controlling an oil path; and

a pressure-taking valve (3) configured to apply a part of the output pressure of the fixed displacement pump (2) to the control end of the variable-displacement control mechanism through the control oil passage to increase the maximum displacement of the variable-displacement pump (1) when the driving rotation speed of the driving mechanism increases.

2. The load-sensitive pump system according to claim 1, wherein the pressure-taking valve (3) is a fixed-ratio pressure-taking valve, and the partial output pressure acting on the control end of the variable control mechanism is configured to increase as the working oil pressure of the fixed-displacement pump (2) increases.

3. The load-sensitive pump system according to claim 1, wherein the pressure taking valve (3) has a first oil inlet (P1), a first oil outlet (P2) and a second oil outlet (P3), the pressure taking valve (3) comprises a damping (31) and a pilot-controlled proportional valve (32), a fixed-quantity working oil port (B2) of the fixed-quantity pump (2) is communicated with the first oil inlet (P1), the damping (31) is arranged on a passage of the first oil inlet (P1) and the first oil outlet (P2), the pilot-controlled proportional valve (32) is arranged on a passage of the first oil inlet (P1) and the second oil outlet (P3), a first control end of the pilot-controlled proportional valve (32) is communicated with the first oil inlet (P1), a second control end of the pilot-controlled proportional valve (32) is communicated with the first oil inlet (P2) and the second oil outlet (P3), the second oil outlet (P3) is communicated with the control end of the variable control mechanism.

4. The load-sensitive pump system according to claim 1, wherein the variable control mechanism comprises a power control valve (6) and a variable cylinder (7) for controlling the swash plate swing angle of the variable pump (1), the power control valve (6) can change the oil supply amount of the control oil path to the variable cylinder (7) to realize the adjustable displacement of the variable pump (1), a variable working oil port (B1) of the variable pump (1) is communicated with a first control end of the power control valve (6) through the control oil path, and the pressure taking valve (3) applies part of the output pressure of the fixed displacement pump (2) to a second control end of the power control valve (6) through the control oil path.

5. The load-sensitive pump system according to claim 4, wherein the control oil circuit supplies oil to a rodless cavity of the variable cylinder (7), a piston rod of the variable cylinder (7) is used for controlling the swash plate swing angle of the variable pump (1), the power control valve (6) is a pilot-controlled proportional valve, the variable pump (1) supplies oil to the rodless cavity of the variable cylinder (7) through the power control valve (6) when a spool of the power control valve (6) is in a first control position state, and the rodless cavity of the variable cylinder (7) drains oil through the power control valve (6) when the spool of the power control valve (6) is in a second control position state.

6. Load sensitive pump system according to claim 5, characterized in that the piston rod is provided with a swash plate tilt feedback (8), and that a swash plate tilt feedback spring (9) is provided in a pre-stressed state between the swash plate tilt feedback (8) and the second control end of the power control valve (6).

7. The load-sensitive pump system according to claim 4, wherein the variable control mechanism further comprises a flow control valve (5) and a pressure control valve (4) which are arranged on the control oil path, a load feedback end of the flow control valve (5) is communicated with a load feedback port (X), and the control oil of the control oil path is provided by a working oil path of the variable pump (1).

8. A hydraulic control system comprising a load sensitive pump system according to any one of claims 1 to 7.

9. A working machine comprising a load sensitive pump system according to any one of claims 1 to 7.

10. A working machine according to claim 9, characterized in that the working machine is a crane.

Technical Field

The disclosure relates to the technical field of engineering machinery, in particular to a load sensitive pump system, a hydraulic control system and engineering machinery.

Background

The power device of the crane mostly adopts an engine to drive a hydraulic pump group to provide power for a boarding operation system (hoisting, amplitude variation, stretching, rotation and the like) of the crane, the output torque of the engine is firstly increased and then reduced along with the variation trend of the rotation speed increase, the maximum torque point is always in the middle rotation speed section, the output torque is very low under low rotation speed, for example, 800Nm when 800rpm is adopted, and 1600Nm when 1400rpm is adopted.

A load sensitive pump system is commonly used in a crane hydraulic system, a hydraulic control handle is adopted to control a load sensitive multi-way valve, a load sensitive oil way on the valve is connected to a load sensitive pump, the speed regulation effect of the system is realized by controlling the opening of the multi-way valve, and in addition, the rotating speed of a hydraulic pump can be changed by controlling the rotating speed of an engine to improve the output flow of the system.

Known from the input torque formula T of the hydraulic pump P × V/2 pi, the larger the load pressure P is, the larger the displacement of the pump has a maximum limit value Vmax, otherwise the torque T exceeds the output torque of the current engine, which may cause the engine to stall, for this reason, when a crane product selects a load-sensitive pump, the crane product generally has a constant power control function (LA), which is determined according to the input torque of the power unit at the lowest rotation speed, and after the set value is fixed, even if the rotation speed of the engine is increased, the torque that can be provided is increased, the displacement of the pump still decreases after the pump outlet pressure reaches a certain value, so that the output power of the hydraulic system decreases, and the power utilization rate of the engine decreases.

Disclosure of Invention

The inventor researches and finds that the utilization rate of the pump driving mechanism is not high in the related technology.

In view of this, the embodiments of the present disclosure provide a load-sensitive pump system, a hydraulic control system, and an engineering machine, which can effectively improve the utilization rate of a driving mechanism.

Some embodiments of the present disclosure provide a load sensitive pump system comprising:

a variable displacement pump;

the constant delivery pump and the variable delivery pump are driven by the same driving mechanism;

a variable control mechanism for controlling the variable pump;

controlling an oil path; and

and the pressure taking valve is configured to apply partial output pressure of the fixed displacement pump to the control end of the variable control mechanism through the control oil path so as to increase the maximum displacement of the variable displacement pump when the driving rotation speed of the driving mechanism is increased.

In some embodiments, the pressure-taking valve is a fixed-ratio pressure-taking valve, and the partial output pressure acting on the control end of the variable-amount control mechanism is configured to increase as the working oil pressure of the fixed-amount pump increases.

In some embodiments, the pressure taking valve has a first oil inlet, a first oil outlet and a second oil outlet, the pressure taking valve includes a damping and hydraulic control proportional valve, the fixed displacement oil port of the fixed displacement pump is communicated with the first oil inlet, the damping is arranged on the passage of the first oil inlet and the first oil outlet, the hydraulic control proportional valve is arranged on the passage of the first oil inlet and the second oil outlet, a first control end of the hydraulic control proportional valve is communicated with the first oil inlet, a second control end of the hydraulic control proportional valve is communicated with both the first oil outlet and the second oil outlet, and the second oil outlet is communicated with the control end of the variable control mechanism.

In some embodiments, the variable control mechanism comprises a power control valve and a variable cylinder for controlling the swash plate swing angle of the variable pump, the power control valve can change the oil supply amount of a control oil path to the variable cylinder to realize the adjustable displacement of the variable pump, a variable working oil port of the variable pump is communicated with a first control end of the power control valve through the control oil path, and a pressure taking valve applies part of the output pressure of the fixed displacement pump to a second control end of the power control valve through the control oil path.

In some embodiments, the control oil circuit supplies oil to the rodless cavity of the variable cylinder, the piston rod of the variable cylinder is used for controlling the swash plate swing angle of the variable pump, the power control valve is a hydraulic control proportional valve, the variable pump supplies oil to the rodless cavity of the variable cylinder through the power control valve when the valve core of the power control valve is in a first control position state, and the rodless cavity of the variable cylinder drains oil through the power control valve when the valve core of the power control valve is in a second control position state.

In some embodiments, the piston rod is provided with a swash plate swing angle feedback piece, and a swash plate swing angle feedback spring in a pre-compression state is arranged between the swash plate swing angle feedback piece and the second control end of the power control valve.

In some embodiments, the variable control mechanism further comprises a flow control valve and a pressure control valve arranged on the control oil path, a load feedback end of the flow control valve is communicated with the load feedback port, and the control oil of the control oil path is provided by a working oil path of the variable pump.

Some embodiments of the present disclosure provide a hydraulic control system comprising the aforementioned load sensitive pump system.

Some embodiments of the present disclosure provide a work machine including the aforementioned load sensitive pump system.

In some embodiments, the work machine is a crane.

Therefore, according to the embodiment of the disclosure, the pressure taking valve is arranged, and the pressure taking valve introduces part of pressure change signals of the fixed displacement pump into the control end of the variable displacement control mechanism, so that the maximum displacement of the variable displacement pump can be increased by the variable displacement control mechanism when the driving rotating speed of the driving mechanism is increased.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

The present disclosure may be more clearly understood from the following detailed description, taken with reference to the accompanying drawings, in which:

FIG. 1 is a schematic block diagram of some embodiments of the disclosed load sensitive pump system.

Description of the reference numerals

1. A variable displacement pump; 2. a constant delivery pump; 3. a pressure-taking valve; 4. a pressure control valve; 5. a flow control valve; 6. a power control valve; 7. a variable cylinder; 8. a swash plate swing angle feedback member; 9. a swash plate swing angle feedback spring; 31. damping; 32. a hydraulic control proportional valve; p1, a first oil inlet; p2, a first oil outlet; p3, a second oil outlet; b1, variable working oil port; b2, a quantitative working oil port; x, a load feedback port; y, control port.

Detailed Description

Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the disclosure, its application, or uses. The present disclosure may be embodied in many different forms and is not limited to the embodiments herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that: the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values set forth in these embodiments are to be construed as merely illustrative, and not as limitative, unless specifically stated otherwise.

The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element preceding the word covers the element listed after the word, and does not exclude the possibility that other elements are also covered. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

In the present disclosure, when a specific device is described as being located between a first device and a second device, there may or may not be intervening devices between the specific device and the first device or the second device. When a particular device is described as being coupled to other devices, the particular device may be directly coupled to the other devices without intervening devices or may be directly coupled to the other devices with intervening devices.

All terms used in the present disclosure have the same meaning as understood by one of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

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 a load-sensitive hydraulic system, the variable control mode of a variable pump comprises pressure control, flow control and power control, wherein the pressure control limits the maximum pressure of the outlet of the variable pump within the control range of the variable pump, the variable pump only provides the hydraulic oil flow required by an actuating element, and if the working pressure exceeds the pressure set value set at a pressure valve, the variable pump adjusts to smaller displacement so as to reduce the control deviation; flow control is achieved by using a variable orifice (e.g., a directional valve) to adjust the differential pressure upstream and downstream of the orifice, and this differential pressure controls the flow of the variable displacement pump, which will have an output flow equal to the flow actually required by the actuator, regardless of the pressure level change; the power control is to keep constant transmission torque under the condition that the working pressure is constantly changed, the angle of a swash plate of the variable pump (the displacement of the variable pump) needs to be changed, and the output flow and the pressure of the variable pump are kept unchanged under the fixed input rotating speed, so that the purpose of constant power control is achieved.

As shown in fig. 1, some embodiments of the present disclosure provide a load sensitive pump system comprising: a variable displacement pump 1; the constant delivery pump 2 and the variable delivery pump 1 are driven by the same driving mechanism; a variable control mechanism for controlling the variable pump 1; controlling an oil path; and a pressure-taking valve 3 configured to apply a part of the output pressure of the fixed displacement pump 2 to a control end of the variable-displacement control mechanism through a control oil passage to increase the maximum displacement of the variable-displacement pump 1 when the driving rotation speed of the driving mechanism increases.

As shown in fig. 1, the variable pump 1 and the fixed displacement pump 2 are both driven by the same driving mechanism, for example, driven by an engine, the variable pump 1 is communicated with the fixed displacement pump 2 in terms of rotation speed change, when the rotation speed of the fixed displacement pump 2 rises, the rotation speed of the variable pump 1 also rises correspondingly, and by providing the pressure-taking valve 3, the pressure-taking valve 3 introduces part of pressure change signals of the fixed displacement pump into a control end of the variable control mechanism, so that the maximum displacement of the variable pump 1 can be increased by the control mechanism when the driving rotation speed of the driving mechanism rises, and the variable control of the power of the variable pump is realized at different input rotation speeds, so that the power utilization rate of the hydraulic pump is improved, thereby effectively reducing the maximum working rotation speed of the driving mechanism and realizing the energy-saving effect of the hydraulic system. The load-sensitive pump system disclosed by the invention does not need to additionally increase an electric controller or a wire harness and the like, realizes the effect of variable control of power along with the rotating speed through the self hydraulic control oil way, and has higher implementability.

In some embodiments, the pressure-taking valve 3 is a fixed-ratio pressure-taking valve, and the partial output pressure acting on the control end of the variable control mechanism is configured to increase with the increase of the working oil pressure of the fixed displacement pump 2, so that the rotating speed change signal of the driving mechanism can be accurately obtained, and the control accuracy is effectively improved.

Regarding the structure of the pressure taking valve, in some embodiments, as shown in fig. 1, the pressure taking valve 3 has a first oil inlet P1, a first oil outlet P2 and a second oil outlet P3, the pressure taking valve 3 includes a damper 31 and a pilot-controlled proportional valve 32, a fixed-quantity working oil port B2 of the fixed-quantity pump 2 communicates with the first oil inlet P1, the damper 31 is disposed on a passage of a first oil inlet P1 and a first oil outlet P2, the pilot-controlled proportional valve 32 is disposed on a passage of a first oil inlet P1 and a second oil outlet P3, a first control end of the pilot-controlled proportional valve 32 communicates with a first oil inlet P1, a second control end of the pilot-controlled proportional valve 32 communicates with both the first oil outlet P2 and a second oil outlet P3, and a second oil outlet P3 communicates with a control end of the variable control mechanism.

The damping 31 plays a role of pressure reduction, by arranging the pilot-controlled proportional valve 32, the oil pressure of the first oil inlet P1 acts on the first control end of the pilot-controlled proportional valve 32, the oil pressures of the first oil outlet P2 and the second oil outlet P3 act on the second control end of the pilot-controlled proportional valve 32, because the areas of the first control end and the second control end of the valve core are equal, when the pilot-controlled proportional valve 32 is balanced, the oil pressure of the first oil inlet P1 is equal to the sum of the oil pressures of the first oil outlet P2 and the second oil outlet P3, namely the oil pressure of the second oil outlet P3 is equal to the oil pressure of the first oil inlet P1 minus the oil pressure of the first oil outlet P2, the oil pressure of the second oil outlet P3 is the pressure drop generated by the damping 31, because the damping 31 is proportionally reduced, when the oil pressure of the first oil inlet P1 is increased, the oil pressures of the first oil outlet P2 and the second oil outlet P3 are both increased, and the oil pressure of the second oil outlet P3 is applied to the control end of the variable control mechanism, the variable displacement control mechanism is capable of increasing the maximum displacement of the variable displacement pump 1 when the driving rotational speed of the drive mechanism is increased.

It should be noted that the oil pressure of the second oil outlet P3 is only a small part of the oil pressure of the first oil outlet P2, and the oil pressure of the first oil outlet P2 occupies a large part, so the setting of the pressure valve 3 does not affect the power output of the first oil outlet P2 as the working power output port.

Regarding the structure of the variable control mechanism, in some embodiments, as shown in fig. 1, the variable control mechanism includes a power control valve 6 and a variable cylinder 7 for controlling the swash plate swing angle of the variable pump 1, the power control valve 6 can change the oil supply amount of a control oil path to the variable cylinder 7 to realize the adjustable displacement of the variable pump 1, a variable working oil port B1 of the variable pump 1 is communicated with a first control end (left control end in fig. 1) of the power control valve 6 through the control oil path, and the pressure taking valve 3 acts the oil pressure of a second oil outlet P3 on a second control end (right control end in fig. 1) of the power control valve 6 through the control oil path communication control port Y, which is beneficial to changing the spool position of the power control valve 6, and then changes the oil supply amount of the control oil path to the variable cylinder 7, thereby realizing the adjustable displacement of the variable pump 1 and having high feasibility of implementation.

As shown in fig. 1, in some embodiments, the control oil circuit supplies oil to the rodless cavity of the variable cylinder 7, the piston rod of the variable cylinder 7 is used for controlling the swash plate swing angle of the variable pump 1, the power control valve 6 is a pilot-controlled proportional valve, the variable pump 1 supplies oil to the rodless cavity of the variable cylinder 7 through the power control valve 6 in a state where the spool of the power control valve 6 is in the first control position (left position shown in fig. 1), and the rodless cavity of the variable cylinder 7 drains oil through the power control valve 6 in a state where the spool of the power control valve 6 is in the second control position (right position shown in fig. 1). With this arrangement, the oil pressure at the second outlet port P3 acts on the second control end of the power control valve 6, which facilitates the power control valve 6 to be maintained in the second control position (right position shown in fig. 1), and the swash plate angle of the variable displacement pump 1 is controlled to be increased compared to the case where the oil pressure at the second outlet port P3 does not act, thereby increasing the displacement of the variable displacement pump 1.

In some embodiments, as shown in fig. 1, the piston rod is provided with a swash plate swing angle feedback member 8, and a swash plate swing angle feedback spring 9 in a pre-compressed state is provided between the swash plate swing angle feedback member 8 and the second control end of the power control valve 6. By providing the swash plate swing angle feedback spring 9 in the pre-compression state, the oil pressure of the second oil outlet P3 and the swash plate swing angle feedback spring 9 act together on the second control end of the power control valve 6, and are balanced with the oil pressure of the variable working port B1 of the variable displacement pump 1 acting on the first control end of the power control valve 6.

For how to implement the load-sensitive differential pressure control, in some embodiments, as shown in fig. 1, the variable control mechanism further includes a flow control valve 5 and a pressure control valve 4 disposed on the control oil path, a load feedback end of the flow control valve 5 is communicated with the load feedback port X, the control oil of the control oil path is provided by the working oil path of the variable pump 1, and the flow control valve 5 and the pressure control valve 4 are technical means known in the art and will not be described herein again.

The following description will be made of the control principle of the load-sensitive pump system of the present disclosure, taking the embodiment shown in fig. 1 as an example, applied to a crane, and taking the driving mechanism as an example, as follows:

when the crane is in operation on the train, the engine speed usually works in a low speed state, the maximum output torque value of the engine is low, and in order to prevent the engine from being flamed out due to overlarge load, the maximum displacement output of the variable displacement pump 1 needs to be limited.

When the load-sensitive pump system works normally, the flow control valve 5 of the load-sensitive pump system works, the variable displacement pump 1 provides the flow required by the system, and the pump displacement is gradually increased when the rotating speed is increased.

If the pressure taking valve 3 is not arranged for pressure introduction, the power control valve 6 enables the valve core to move rightwards to work to the left under the action of oil pressure of a variable working oil port B1 of the variable pump 1, then the swash plate swing angle feedback piece 8 and the piston rod are driven to move rightwards, the variable pump 1 supplies oil to a rodless cavity of the variable cylinder 7 through the power control valve 6, the piston rod moves leftwards, and finally balance is achieved, so that the pump displacement is stabilized at Vmax 1;

after the pressure is introduced by arranging the pressure taking valve 3, the oil pressure of a second oil outlet P3 output by the pressure taking valve 3 is correspondingly increased along with the rotating speed, the pressure output to a control port Y of the variable pump 1 is also increased, so that the power control valve 6 can move leftwards to work to the right, the rodless cavity of the variable cylinder 7 drains oil through the power control valve 6, a piston rod moves leftwards, and when new balance is reached, the pump displacement is stabilized at Vmax₂Compared with the maximum displacement Vmax of the variable displacement pump at the same rotating speed₁The displacement of the variable displacement pump 1 is increased, and the output torque of the system is correspondingly increased, so that the displacement of the variable displacement pump 1 is increased under the same high rotating speed, and the power utilization rate of the hydraulic system is higher;

the pressure control valve 4 is used for the maximum pressure limit of the variable displacement pump 1, and when the outlet pressure of the variable displacement pump 1 exceeds this value, the outlet pressure of the variable displacement pump 1 directly acts on the rodless chamber of the variable displacement cylinder 7, so that the displacement of the variable displacement pump 1 is reduced.

Some embodiments of the present disclosure provide a hydraulic control system comprising the aforementioned load sensitive pump system.

Some embodiments of the present disclosure provide a work machine including the aforementioned load sensitive pump system. The disclosed load sensitive pump system is particularly suited for use with a crane, and thus, in some embodiments, the work machine is a crane.

Thus, various embodiments of the present disclosure have been described in detail. Some details that are well known in the art have not been described in order to avoid obscuring the concepts of the present disclosure. It will be fully apparent to those skilled in the art from the foregoing description how to practice the presently disclosed embodiments.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. It will be understood by those skilled in the art that various changes may be made in the above embodiments or equivalents may be substituted for elements thereof without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.