EP4265918A1

EP4265918A1 - Balance cylinder hydraulic system

Info

Publication number: EP4265918A1
Application number: EP21905211.5A
Authority: EP
Inventors: Xianyu ZHU; Yi SHEN; Sijing CHENG; Zhenyu Wang; Dong Lu
Original assignee: Kuka Robotics Guangdong Co Ltd; KUKA Robotics Guangdong Co Ltd
Current assignee: Kuka Robotics Guangdong Co Ltd; KUKA Robotics Guangdong Co Ltd
Priority date: 2020-12-15
Filing date: 2021-09-29
Publication date: 2023-10-25
Also published as: WO2022127281A1; CN112610542B; CN112610542A

Abstract

The present disclosure provides a balance cylinder hydraulic system, comprising: a valve assembly; and a balance cylinder comprising a housing, a piston member, and a first cavity, a second cavity and a third cavity which are obtained by the piston member movably sealing a hollow region enclosed by the housing, wherein the area of the piston member acting on the first cavity is equal to the area of the piston member acting on the second cavity, the pressure of the first cavity is equal to the pressure of the second cavity and higher than the pressure of the third cavity, and a compensation oil passage controlled by the valve assembly is provided between the first cavity and the third cavity; a first accumulator, between the first accumulator and the first cavity, a target oil passage and a first oil passage which are controlled by the valve assembly being provided; and a second accumulator in communication with the second cavity, a second oil passage controlled by the valve assembly being provided between the second accumulator and the first cavity. In the embodiments of the present disclosure, after the internal leakage in the balance cylinder occurs, the system can automatically compensate for the internal leakage, without stopping the operation of the balance cylinder.

Description

This application claims the priority of Chinese Patent Application No. 202011481878.3 filed on December 15, 2020 and entitled "Balance Cylinder Hydraulic System", the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to the field of hydraulic systems, in particular to a balance cylinder hydraulic system.

BACKGROUND

In the industry, the balance cylinder plays an irreplaceable role as a component for providing balance force. A dynamic seal is usually used between the piston and the cylinder wall in the hydraulic balance cylinder, which leads to inevitable internal leakage in the balance cylinder. Specifically, internal leakage refers to the leakage of oil from a high-pressure cavity with a higher pressure to a low-pressure cavity with a lower pressure. For a long time, the internal leakage will cause the accumulator pressure of the balance cylinder to drop, which leads to the decrease of the balance force of the balance cylinder.
In the prior art, in order to ensure the balance force of the balance cylinder, the pressure of the accumulator needs to be monitored, and when the pressure of the accumulator is less than a certain value, the operation of the balance cylinder is stopped to charge the accumulator. This method requires the accumulator to be constantly monitored from the outside, and the balancing cylinder needs to be stopped from time to time, thus affecting the industrial production process.

Summary

An object of the present disclosure is to propose a balance cylinder hydraulic system, which can automatically complete the internal leakage compensation without stopping the operation of the balance cylinder after the internal leakage of the balance cylinder occurs; meanwhile, it also can automatically complete internal leakage compensation in response to a decrease in the pressure of the accumulator without monitoring the pressure of the accumulator by external equipment.
According to an aspect of the embodiments of the present disclosure, a balance cylinder hydraulic system is disclosed, comprising:

a valve assembly, which is configured to control the opening or closing of each oil circuit in the system under the action of the pressure of each component in the system;
and a balance cylinder comprising a housing, a piston member, and a first cavity, a second cavity and a third cavity which are obtained by the piston member movably sealing a hollow region enclosed by the housing, wherein the area of the piston member acting on the first cavity is equal to the area of the piston member acting on the second cavity, the pressure of the first cavity is equal to the pressure of the second cavity and higher than the pressure of the third cavity, and a compensation oil circuit controlled by the valve assembly is provided between the first cavity and the third cavity;
a first accumulator, and a target oil circuit and a first oil circuit which are controlled by the valve assembly being provided between the first accumulator and the first cavity;
and a second accumulator in communication with the second cavity, and a second oil circuit controlled by the valve assembly being provided between the second accumulator and the first cavity;
wherein, when the pressure of the first accumulator is equal to the pressure of the second accumulator, the valve assembly only opens the target oil circuit, so that with the lifting and lowering of the piston member, the charging and discharging of the oil between the first accumulator and the first cavity is synchronized with the charging and discharging of the oil between the second accumulator and the second cavity in an equal volume;
when the pressure of the first accumulator is not equal to the pressure of the second accumulator, the lift of the piston member triggers the valve assembly to open only the compensation oil circuit, so that with the lifting of the piston member, the oil is input into the first cavity from the third cavity, and the lowering of the piston member triggers the valve assembly to open only the first oil circuit or the second oil so that with the descending of the piston member, the oil is input into a low-pressure accumulator from the first cavity,
wherein the low-pressure accumulator is the accumulator with a lower pressure among the first accumulator and the second accumulator.

According to an exemplary embodiment of the present disclosure, the valve assembly comprises a one-way valve and a reversing valve, wherein the one-way valve is used to control the unidirectional flow of oil in each oil circuit in the system, and the reversing valve is used to switch the various oil circuits in the system.
According to an exemplary embodiment of the present disclosure, the one-way valve comprises a compensation one-way valve disposed in the compensation oil circuit, and the oil flow direction of the compensation one-way valve is from the third cavity to the first cavity.
According to an exemplary embodiment of the present disclosure, the one-way valve comprises a second one-way valve disposed in the second oil circuit, and the oil flow direction of the second one-way valve is from the first cavity to the second accumulator.
According to an exemplary embodiment of the present disclosure, the one-way valve further comprises a first one-way valve disposed in the first oil circuit, wherein a liquid inlet end of the second one-way valve is connected to the liquid inlet end of the one-way valve, and the oil flow direction of the first one-way valve is from the first cavity to the first accumulator.
According to an exemplary embodiment of the present disclosure, the reversing valve comprises a hydraulic reversing valve for detecting the pressure of the first accumulator and the pressure of the second accumulator, and switch the oil circuit under the action of the pressure of the first accumulator and the pressure of the second accumulator.
According to an exemplary embodiment of the present disclosure, the main port of the hydraulic reversing valve is communicated with the first cavity, and the first branch port of the hydraulic reversing valve is communicated with the first accumulator to form the target oil circuit, the second branch port of the hydraulic reversing valve is simultaneously communicated to the first accumulator and the second accumulator to form the first oil circuit and the second oil circuit;

wherein, when the pressure of the first accumulator is equal to the pressure of the second accumulator, the main port is only communicated with the first branch port;
wherein, when the pressure of the first accumulator is not equal to the pressure of the second accumulator, the main port is only communicated with the second branch port;

According to an exemplary embodiment of the present disclosure, the initial pressure of the first accumulator is equal to the initial pressure of the second accumulator.
According to an exemplary embodiment of the present disclosure, the axial cross-section side of the first cavity is convex, the axial cross-section of the second cavity is in the shape of two symmetrically separated steps, and the third cavity includes a fourth cavity and a fifth cavity that communicate with each other, the axial section of the fourth cavity is in the shape of two symmetrically separated inverted steps, and the axial section of the fifth cavity is in the form of two symmetrically separated rectangles;
The first cavity is located in the center of the hollow area surrounded by the shell, the second cavity is attached to the first cavity and is located at the lower part of the hollow area, and the fourth cavity is matched with the second cavity and is attached to the first cavity and is arranged on the upper part of the hollow area, and the fifth cavity is matched with the table provided by the second cavity and is attached to the fourth cavity and is arranged on the periphery of the hollow area.
According to an exemplary embodiment of the present disclosure, an area of the piston member acting on the fourth cavity is equal to an area of the piston member acting on the fifth cavity.
In the hydraulic system of the balance cylinder provided by the embodiment of the present disclosure, through the compensation oil circuit controlled by the valve assembly and arranged between the first cavity and the third cavity, the first oil circuit controlled by the valve assembly and arranged between the first accumulator and the first cavity, and the second oil circuit controlled by the valve assembly and arranged between the second accumulator and the second cavity, after the leakage in the balance cylinder occurs, the oil leaking to the third cavity will be automatically replenished to the low pressure accumulator through the first cavity as the piston rod rises and falls. Therefore, the system can automatically complete the internal leakage compensation without stopping the operation of the balance cylinder after the internal leakage of the balance cylinder occurs; meanwhile, it also can automatically complete internal leakage compensation in response to a decrease in the pressure of the accumulator without monitoring the pressure of the accumulator by external equipment.
Other features and advantages of the present disclosure will become apparent from the following detailed description, or be learned in part by practice of the present disclosure.
It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and cannot limit the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present disclosure will become more apparent from the detailed description of example embodiments thereof with reference to the accompanying drawings.

FIG. 1 shows a schematic structural diagram of a balance cylinder hydraulic system according to an embodiment of the present disclosure.
FIG. 2 shows a schematic structural diagram of the balance cylinder in FIG. 1 according to an embodiment of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS:

1- balance cylinder, 2- hydraulic rod, 3- first accumulator, 4- second accumulator, 5-compensation one-way valve, 6- first one-way valve, 7- second one-way valve, 8- The first hydraulic reversing valve, 9- the second hydraulic reversing valve, the oil inlet and outlet of the 10-the oil inlet and outlet of cavity A, 11- The oil inlet and outlet of cavity B, 12-The oil inlet and outlet of cavity D, 13-The oil inlet and outlet of cavity C.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments, however, can be embodied in various forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that this description of the present disclosure will be thorough and complete, and will consolidate the concept of the example embodiments. It will be fully conveyed to those skilled in the art. The drawings are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated descriptions will be omitted.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments. In the following description, numerous specific details are provided in order to give a thorough understanding of example embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of the specific details, or other methods, components, steps, etc. may be employed. In other instances, well-known structures, methods, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the present disclosure.
The present disclosure provides a balance cylinder hydraulic system, comprising:

a valve assembly, which is configured to control the opening or closing of each oil circuit in the system under the action of the pressure of each component in the system;
and a balance cylinder comprising a housing, a piston member, and a first cavity, a second cavity and a third cavity which are obtained by the piston member movably sealing a hollow region enclosed by the housing, wherein the area of the piston member acting on the first cavity is equal to the area of the piston member acting on the second cavity, the pressure of the first cavity is equal to the pressure of the second cavity and higher than the pressure of the third cavity, and a compensation oil circuit controlled by the valve assembly is provided between the first cavity and the third cavity;
a first accumulator, between the first accumulator and the first cavity, a target oil circuit and a first oil circuit which are controlled by the valve assembly being provided;
and a second accumulator in communication with the second cavity, a second oil circuit controlled by the valve assembly being provided between the second accumulator and the first;
wherein, when the pressure of the first accumulator is equal to the pressure of the second accumulator, the valve assembly only opens the target oil circuit, so that with the lifting and lowering of the piston member, the charging and discharging of the oil between the first accumulator and the first cavity is synchronized with the charging and discharging of the oil between the second accumulator and the second cavity in an equal volume;
when the pressure of the first accumulator is not equal to the pressure of the second accumulator, the lift of the piston member triggers the valve assembly to open only the compensation oil circuit, so that with the lifting of the piston member, the oil is input into the first cavity from the third cavity, and the lowering of the piston member triggers the valve assembly to open only the first oil circuit or the second oil so that with the descending of the piston member, the oil is input into a low-pressure accumulator from the first cavity,
wherein the low-pressure accumulator is the accumulator with a lower pressure among the first accumulator and the second accumulator.

In detail, the balance cylinder hydraulic system is mainly composed of four major components: balance cylinder, valve assembly, first accumulator, and second accumulator.
The balance cylinder obtains three cavities under the action of the dynamic seal of its piston parts: the first cavity, the second cavity, and the third cavity. With the lifting of the piston piece, the volume of the first cavity and the volume of the second cavity are expanded synchronously; with the descending of the piston piece, the volume of the first cavity and the volume of the second cavity shrink synchronously. The pressure of the first cavity is the same as the pressure of the second cavity and is greater than the pressure of the third cavity.
It should be noted that the three cavities of the balance cylinder are mainly divided based on the pressure level in the cavity, and connected multiple cavities at the same pressure level will be divided into the same cavity, which does not mean that there are only three cavities obtained by dividing the balance cylinder by physical space in the present disclosure.
The first accumulator is mainly used to store the pressure generated by the compression of the first cavity when the first cavity is compressed through the circulation of oil, and to replenish the pressure to the first cavity when the first cavity expands. When no internal leakage occurs, the first accumulator is communicated with the first cavity through the target oil circuit, and the pressure of the first accumulator and the pressure of the first cavity are dynamically maintained the same. Wherein, there are two oil circuits between the first accumulator and the first cavity: the target oil circuit and the first oil circuit. The target oil circuit is used for the first accumulator to store or release the pressure of the first cavity when no internal leakage occurs; the first oil circuit is used to replenish the leaked oil input to the first cavity back to the first accumulator after the internal leakage occurs.
The second accumulator is mainly used to store the pressure generated by the compression of the second cavity when the second cavity is compressed through the circulation of oil, and to replenish the pressure to the second cavity when the second cavity expands. The second accumulator is always communicated with the second cavity, and the pressure of the first accumulator and the pressure of the first cavity are dynamically maintained the same.
When there is no internal leakage, the pressure of the first cavity is the same as the pressure of the second cavity, the pressure of the first accumulator and the pressure of the first cavity are dynamically maintained the same, and the pressure of the second accumulator and the pressure of the second cavity are dynamically maintained the same, so the pressure of the first accumulator is the same as the pressure of the second accumulator When there is no internal leakage.
In addition, since the area of the piston member acting on the first cavity is equal to the area acting on the second cavity by the piston member, therefore, in the case of no internal leakage, with the rise and fall of the piston member, the charging and discharging of oil from the first accumulator into the first cavity is not only synchronized with the charging and discharging of oil from the second accumulator into the second cavity, but also the volume of oil charged and discharged from the first accumulator into the first cavity is equal to the volume of oil charged and discharged from the second accumulator into the second cavity.
Since the cavities in the balance cylinder are dynamically sealed, it is unavoidable that the oil will leak from the place with higher pressure to the place with lower pressure. That is, the oil in the first cavity may leak to the third cavity, or the oil in the second cavity may leak to the third cavity.
If the oil in the first cavity leaks to the third cavity, the pressure in the third cavity increases and the pressure in the first cavity decreases. The first accumulator replenishes its oil to the first cavity, so that the pressure of the first accumulator also decreases. As a result, the pressure of the first accumulator is lower than the pressure of the second accumulator, and the first accumulator is a low-pressure accumulator.
If the oil in the second cavity leaks to the third cavity, the pressure in the third cavity increases and the pressure in the second cavity decreases. The second accumulator replenishes its oil to the first cavity, so that the pressure of the second accumulator also decreases. As a result, the pressure of the second accumulator is lower than the pressure of the first accumulator, and the second accumulator is a low-pressure accumulator.
To automatically replenish the oil leaking to the third cavity to the original cavity after the internal leakage occurs: the compensation oil circuit controlled by the valve assembly is arranged between the first cavity and the third cavity; the first oil circuit controlled by the valve assembly is arranged between the first accumulator and the first cavity; and the second oil circuit controlled by the valve assembly is arranged between the second accumulator and the second cavity.
After the internal leakage occurs, the pressure of the first accumulator is not equal to the pressure of the second accumulator: the lift of the piston member triggers the valve assembly to open only the compensation oil circuit, and with the lifting of the piston member, the oil leaking to the third chamber is input into the first cavity; then, the drop of the piston part triggers the valve assembly to only open the oil circuit between the low pressure accumulator and the first cavity, and as the piston part descends, the leaked oil that is input into the first cavity is input into the low pressure accumulator. Thus, the system realizes compensation for internal leakage of the balance rod.
It can be seen that in the hydraulic system of the balance cylinder provided by the embodiment of the present disclosure, through the compensation oil circuit controlled by the valve assembly and arranged between the first cavity and the third cavity, the first oil circuit controlled by the valve assembly and arranged between the first accumulator and the first cavity, and the second oil circuit controlled by the valve assembly and arranged between the second accumulator and the second cavity, after the leakage in the balance cylinder occurs, the oil leaking to the third cavity will be automatically replenished to the low pressure accumulator through the first cavity as the piston rod rises and falls. Therefore, the system can automatically complete the internal leakage compensation without stopping the operation of the balance cylinder after the internal leakage of the balance cylinder occurs; meanwhile, it also can automatically complete internal leakage compensation in response to a decrease in the pressure of the accumulator without monitoring the pressure of the accumulator by external equipment.
According to an embodiment, the valve assembly comprises a one-way valve and a reversing valve, wherein the one-way valve is used to control the unidirectional flow of oil in each oil circuit in the system, and the reversing valve is used to switch the various oil circuits in the system.
In this embodiment, the valve assembly for controlling each oil circuit in the system includes a one-way valve and a reversing valve. Among them, the one-way valve is used to control the oil in each oil circuit in the system to only flow in one direction fixedly according to the oil flow direction of the one-way valve; the reversing valve is used to control the switching of each oil circuit in the system.
Specifically, the reversing valve is used to only switch to the target oil circuit when the pressure of the first accumulator is equal to the pressure of the second accumulator to open the target oil circuit, so that the first accumulator is communicated with the first cavity; and only switch to the oil circuit between the low-pressure accumulator and the first cavity When the pressure of the first accumulator is not equal to the pressure of the second accumulator, so that the low-pressure accumulator is communicated with the first cavity.
In an exemplary embodiment, the one-way valve comprises a compensation one-way valve disposed in the compensation oil circuit, and the oil flow direction of the compensation one-way valve is from the third cavity to the first cavity.
In this embodiment, a compensation one-way valve is provided on the compensation oil circuit between the first cavity and the third cavity. Under the restriction of the compensation one-way valve, between the first cavity and the third cavity, the oil can only flow from the third cavity to the first cavity.
The advantage of this embodiment is that, through the setting of the compensation one-way valve, it is ensured that the oil leaked to the third cavity will not flow back to the third cavity through the compensation oil circuit after being replenished into the first cavity.
In an embodiment, the one-way valve comprises a second one-way valve disposed in the second oil circuit, and the oil flow direction of the second one-way valve is from the first cavity to the second accumulator.
In this embodiment, a second one-way valve is provided on the second oil circuit between the second accumulator and the first cavity. Under the restriction of the second one-way valve, between the second accumulator and the first cavity, the oil can only flow from the first cavity to the second accumulator.
The advantage of this embodiment is that, through the setting of the second one-way valve, it is ensured that the oil leaked to the third cavity will not flow back to the first cavity through the second oil circuit after being replenished into the first cavity and then replenished into the second accumulator cavity.
In an embodiment, the one-way valve further comprises a first one-way valve disposed in the first oil circuit, wherein a liquid inlet end of the second one-way valve is connected to the liquid inlet end of the one-way valve, and the oil flow direction of the first one-way valve is from the first cavity to the first accumulator.
In this embodiment, while the second one-way valve is provided on the second oil circuit, a first one-way valve is provided on the first oil circuit between the first accumulator and the first cavity. Under the restriction of the first one-way valve, between the first accumulator and the first cavity, the oil can only flow from the first cavity to the first accumulator.
The liquid inlet end of the second one-way valve is communicated with the liquid inlet end of the first one-way valve, that is: when the low-pressure accumulator is the first accumulator and only the first oil circuit is opened, the oil in the first cavity will try to open the second one-way valve to open the second oil circuit while flowing to the first accumulator through the first oil circuit; when the low-pressure accumulator is the second accumulator and only the second oil circuit is opened, the oil in the first cavity will try to open the first one-way valve to open the first oil circuit while flowing to the second accumulator through the second oil circuit.
When the low-pressure accumulator is the first accumulator, since the pressure of the first accumulator is lower than the pressure of the second accumulator, the oil in the first cavity will preferentially flow to the first accumulator, and the pressure of the first accumulator gradually increases. Only when the pressure of the first accumulator rises to be equal to the pressure of the second accumulator (that is, the moment when the compensation of internal leakage oil is completed), the second one-way valve will be opened, and the second oil circuit will be opened; Once both the first oil circuit and the second oil circuit are opened, and the reversing valve can detect that the end assembly of the first oil circuit (i.e., the first accumulator) and the end assembly of the second oil circuit (i.e., the second accumulator) are equal in pressure. That is, the pressure of the first accumulator is detected to be equal to the pressure of the second accumulator, so that the valve assembly instantly opens only the target oil circuit, and the first accumulator and the first cavity are communicated through the target oil circuit, and the balance cylinder operates normally without internal leakage.
Similarly, when the low-pressure accumulator is the second accumulator, since the pressure of the second accumulator is lower than the pressure of the first accumulator, the oil in the first cavity will preferentially flow to the second accumulator, and the pressure of the second accumulator gradually increases. Only when the pressure of the second accumulator rises to be equal to the pressure of the first accumulator, the first one-way valve will be opened, and the second oil circuit will be opened; Once both the first oil circuit and the second oil circuit are opened, and the reversing valve can detect that the end assembly of the first oil circuit and the end assembly of the second oil circuit are equal in pressure. That is, the pressure of the first accumulator is detected to be equal to the pressure of the second accumulator, so that the valve assembly instantly opens only the target oil circuit, and the first accumulator and the first cavity are communicated through the target oil circuit, and the balance cylinder operates normally without internal leakage.
The advantage of this embodiment is that, through the further setting of the second one-way valve, it is ensured that the oil leaked to the third cavity will not flow back to the first cavity through the first oil circuit after being replenished into the first cavity and then replenished into the first accumulator; and the first oil circuit and the second oil circuit share a part of the oil circuit, which simplifies the arrangement of the oil circuit.
In an exemplary embodiment, the reversing valve comprises a hydraulic reversing valve for detecting the pressure of the first accumulator and the pressure of the second accumulator, and switch the oil circuit under the action of the pressure of the first accumulator and the pressure of the second accumulator.
In this embodiment, the hydraulic reversing valve is used for switching the relevant oil circuit of the accumulator in the reversing valve. Pushed by the oil pressure, the internal valve core of the hydraulic reversing valve moves. Specifically, driven by the relative pressure between the first accumulator and the second accumulator, the internal valve core of the hydraulic reversing valve moves, thereby realizing the switching of the oil circuit.
The advantage of this embodiment is that, through the setting of the hydraulic reversing valve, the valve assembly can automatically complete the switching of the oil circuit under the action of the oil pressure in the system.
It should be noted that, in addition to hydraulic reversing valves, other types of reversing valves, such as electromagnetic reversing valves, can also be used according to actual needs. This embodiment is only an exemplary illustration, and should not limit the function and scope of the present disclosure.
In an embodiment, the main port of the hydraulic reversing valve is communicated with the first cavity, and the first branch port of the hydraulic reversing valve is communicated with the first accumulator to form the target oil circuit, the second branch port of the hydraulic reversing valve is simultaneously communicated to the first accumulator and the second accumulator to form the first oil circuit and the second oil circuit;

In this embodiment, the hydraulic reversing valve has one main port and two branch ports; the main port is communicated with the first cavity; the first branch port is communicated with the first accumulator to form a target oil circuit; the second branch port is communicated with the first accumulator to form a first oil circuit, and is communicated with a second accumulator to form a second oil circuit. When the first oil circuit is opened (for example, when the one-way valve on the first oil circuit is opened), the second branch port is communicated with the first accumulator, and when the second oil circuit is opened (for example: when the one-way valve set on the second oil circuit is opened) the second branch port is communicated with the second accumulator; the main port can be communicated with only one branch port at the same time.

wherein, when the pressure of the first accumulator is equal to the pressure of the second accumulator, that is, when the balance cylinder has no internal leakage, the main port is only communicated with the first branch port; Therefore, the first cavity is communicated with the first accumulator through the target oil circuit, and the first accumulator stores or releases the pressure of the first cavity.
wherein, when the pressure of the first accumulator is not equal to the pressure of the second accumulator, that is, when the balance cylinder has internal leakage, the main port is only communicated with the second branch port; Therefore, the first cavity and the first accumulator are communicated through the first oil circuit, and the leaked oil input to the first cavity is replenished back to the first accumulator; or, the first cavity and the second accumulator are communicated through the second oil circuit, and the leaked oil input into the first cavity is replenished back to the second accumulator.

In an embodiment, the initial pressure of the first accumulator is equal to the initial pressure of the second accumulator.
In this embodiment, after the oil is replenished into the system for the first time, the initial pressure of the first accumulator is adjusted to be the same as the initial pressure of the second accumulator.
The advantage of this embodiment is that, by setting the initial pressure of the accumulator to the same level, the balancing cylinder is initially in a state where no adjustment of the accumulator pressure is required.
It should be noted that the initial pressure of the first accumulator may not be equal to the initial pressure of the second accumulator. In this case, the pressure of the first accumulator will be equal to the pressure of the second accumulator after several times of lifting and lowering of the piston member. This embodiment is only an exemplary illustration, and should not limit the function and scope of the present disclosure.
In an embodiment, the axial cross-section side of the first cavity is convex, the axial cross-section of the second cavity is in the shape of two symmetrically separated steps, and the third cavity includes a fourth cavity and a fifth cavity that communicate with each other, the axial section of the fourth cavity is in the shape of two symmetrically separated inverted steps, and the axial section of the fifth cavity is in the form of two symmetrically separated rectangles;
The first cavity is located in the center of the hollow area surrounded by the shell, the second cavity is attached to the first cavity and is located at the lower part of the hollow area, and the fourth cavity is matched with the second cavity and is attached to the first cavity and is arranged on the upper part of the hollow area, and the fifth cavity is matched with the table provided by the second cavity and is attached to the fourth cavity and is arranged on the periphery of the hollow area.
In this embodiment, the low-pressure third cavity is physically divided into two cavities: the fourth cavity and the fifth cavity. The fourth cavity and the fifth cavity is communicated with each other, so the pressure of the fourth cavity is equal to the pressure of the fifth cavity.
Specifically, from the perspective of the axial section of the balance cylinder: the first cavity is in a "convex" shape and is located in the center; the second cavity is in two stepped shapes that are symmetrical to the first cavity, and is attached to the first cavity and is located at the lower part; The fourth cavity is in the shape of two inverted steps symmetrical to the first cavity, and is attached to the first cavity and is arranged on the upper part. The fifth cavity is in the shape of two rectangles that are symmetrical to the first cavity, and is matched with the table provided by the second cavity and is attached to the fourth cavity and is arranged on the periphery.
With the lifting of the piston piece, the volume of the first cavity expands, the volume of the second cavity expands, the volume of the fourth cavity decreases, and the volume of the fifth cavity increases; as the piston piece descends, the volume of the first cavity shrinks, the volume of the second cavity decreases, the volume of the fourth cavity increases, and the volume of the fifth cavity decreases.
In an embodiment, an area of the piston member acting on the fourth cavity is equal to an area of the piston member acting on the fifth cavity.
The advantage of this embodiment is that since the fourth cavity is communicated with the fifth cavity and the volume change of the fourth cavity is opposite to the volume change of the fifth cavity, therefore, by configuring the area of the piston member acting on the fourth chamber to be equal to the area of the piston member acting on the fifth chamber, the oil in the fourth cavity can completely enter the fifth cavity as the piston member rises and falls, or the oil in the fifth cavity can completely enter the fourth cavity.
It should be noted that, the embodiments about the composition structure of the specific cavity of the balancing cylinder are only exemplary descriptions, and should not limit the function and scope of use of the present disclosure.
FIG. 1 shows a schematic structural diagram of a balance cylinder hydraulic system according to an embodiment of the present disclosure.
As shown in FIG. 1 , in this embodiment, the hydraulic system of the balance cylinder includes a balance cylinder 1, a hydraulic rod, 2,a first accumulator 3, a second accumulator 4, a compensation one-way valve5 , a first one-way valve6 , a second one-way valve 7, a first hydraulic reversing valve 8, a second hydraulic reversing valve 9.
Specifically, the balance cylinder 1 is a rodless cavity pressure-charged balance cylinder, including four cavities: cavity A, cavity B, cavity C, and cavity D. Among them, the cavity C is communicated with the cavity D, the pressure of cavity C is equal to the pressure of cavity D; the pressure of cavity A is equal to the pressure of cavity B, and both are greater than the pressure of cavity C and cavity D; when the hydraulic rod 2 is lifted, the volume of cavity A becomes larger, and the pressure of cavity B becomes larger, the volume of cavity becomes larger, the volume of cavity C becomes larger, and the volume of cavity D becomes smaller; when the hydraulic rod 2 descends, the volume of cavity A becomes smaller, the volume of cavity B becomes smaller, the volume of cavity C becomes smaller, and the volume of cavity D becomes larger.
The initial pressure of the first accumulator 3 is equal to the initial pressure of the second accumulator 4; the second accumulator 4 is always communicated with the B cavity.
The two ends of the first hydraulic reversing valve 8 are respectively 1E and 2E. Among them, 1E detects the pressure of the first accumulator 3 and is affected by the pressure of the first accumulator 3; 2E detects the pressure of the second accumulator 4 and is affected by the pressure of the second accumulator 4; When the pressure of the accumulator 3 is equal to the pressure of the second accumulator 4, C1 is communicated with V1; when the pressure of the first accumulator 3 is not equal to the pressure of the second accumulator 4, C1 is communicated with V2.
The two ends of the second hydraulic reversing valve 9 are respectively 1F and 2F. Among them, 1F detects the pressure of cavity D and is affected by the pressure of cavity D; the pressure of 2F is fixed equal to the initial pressure of cavity D; when the pressure of cavity C is higher than the initial pressure of cavity D, D1 is communicated with P1.
When the pressure of the first accumulator 3 is equal to the pressure of the second accumulator 4 (that is, in the case of no internal leakage of the balance cylinder 1), C1 is communicated with V1, and D1 is communicated with P1, so that the first accumulator 3 is communicated with cavity A. As the hydraulic rod 2 rises and falls, the charge and discharge of the oil between the first accumulator 3 and the cavity A is synchronized with the charge and discharge of the oil between the second accumulator 4 and the cavity B.
In the case that the pressure of the first accumulator 3 is lower than the pressure of the second accumulator 4 (that is, in the case where the oil in cavity A of the balance cylinder 1 leaks to cavity D and cavity C), the pressure in cavity C and Cavity D are both increased, C1 is communicated with V2, so that cavity C is communicated with cavity A. With the lifting of the hydraulic rod 2, the oil in the cavity C is input to the cavity A; Then, with the lowering of the hydraulic rod 2, since the pressure of the first accumulator 3 on the right side is lower, the oil preferentially pushes the one-way valve 6, so that the oil in the cavity A is replenished to the first accumulator 3; With the replenishment of oil, when the pressure of the first accumulator 3 is equal to that of the second accumulator 4, the one-way valve 7 is also pushed open. The first hydraulic reversing valve 8 detects that the first accumulator 3 and the second accumulator 4 are at the same pressure. At this time, C1 is communicated with V1.
In the case that the pressure of the second accumulator 4 is lower than the pressure of the first accumulator 3 (that is, in the case where the oil in cavity B of the balance cylinder 1 leaks to cavity D and cavity C), the pressure in cavity C and Cavity D are both increased, C1 is communicated with V2, so that cavity C is communicated with cavity A. With the lifting of the hydraulic rod 2, the oil in the cavity C is input to the cavity A; Then, with the lowering of the hydraulic rod 2, since the pressure of the second accumulator 4 on the left side is lower, the oil preferentially pushes the one-way valve 6, so that the oil in the cavity A is replenished to the second accumulator 4; With the replenishment of oil, when the pressure of the second accumulator 4 is equal to that of the first accumulator 3, the one-way valve 7 is also pushed open. The first hydraulic reversing valve 8 detects that the first accumulator 3 and the second accumulator 4 are at the same pressure. At this time, C1 is communicated with V1.
FIG. 2 shows a schematic structural diagram of the balance cylinder in FIG. 1 according to an embodiment of the present disclosure.
As shown in Fig. 2, the balance cylinder 1 includes four cavities: cavity A, cavity B, cavity C, and cavity D. The oil inlet and outlet of cavity A is 10, which is used to exchange oil with cavity C or the first accumulator 3 or the second accumulator 4; the oil inlet and outlet of cavity B is 11, which is used to exchange oil with cavity A or the second accumulator 4; the oil inlet and outlet of the C cavity is 13, which is used to exchange oil with the cavity A; the oil inlet and outlet of cavity D is 12, which is used to apply pressure on the second hydraulic reversing valve 9.
Among them, the area ΠD₃ ² of the hydraulic rod 2 acting on the cavity A is equal to the area (ΠD₄ ²- ΠD₃ ²) of the hydraulic rod 2 acting on the cavity B, so that in the case of no internal leakage: with the lifting of the hydraulic rod 2, the first accumulator 3 and the second accumulator 4 can simultaneously charge and discharge the same volume of oil, and the pressure of the first accumulator 3 is always the same as the pressure of the second accumulator 4.
The area (ΠD₁ ²- ΠD₂ ²) of the hydraulic rod 2 acting on the cavity C is equal to the area (Π D₄ ²- ΠD₁ ²) of the hydraulic rod 2 acting on the cavity D, so that with the lifting of the hydraulic rod 2, the oil in cavity C can completely enter the cavity D, or, the oil in the cavity D can completely enter the cavity C.
It should be noted that, FIG. 1 to FIG. 2 only exemplarily show a feasible solution of an embodiment of the present disclosure, and should not limit the function and scope of use of the present disclosure.
Other embodiments of the present disclosure will readily suggest themselves to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or techniques in the technical field not disclosed by the present disclosure. The specification and examples are to be regarded as exemplary only, with the true scope and spirit of the disclosure being indicated by the appended claims.

Claims

A balance cylinder hydraulic system, characterized in that, comprising: a valve assembly;
a valve assembly, which is configured to control the opening or closing of each oil circuit in the system under the action of the pressure of each component in the system;

and a balance cylinder comprising a housing, a piston member, and a first cavity, a second cavity and a third cavity which are obtained by the piston member movably sealing a hollow region enclosed by the housing, wherein the area of the piston member acting on the first cavity is equal to the area of the piston member acting on the second cavity, the pressure of the first cavity is equal to the pressure of the second cavity and higher than the pressure of the third cavity, and a compensation oil passage controlled by the valve assembly is provided between the first cavity and the third cavity;

a first accumulator, a target oil circuit and a first oil circuit which are controlled by the valve assembly being provided between the first accumulator and the first cavity;

and a second accumulator in communication with the second cavity, a second oil circuit controlled by the valve assembly being provided between the second accumulator and the first;

wherein, when the pressure of the first accumulator is equal to the pressure of the second accumulator, the valve assembly only opens the target oil circuit, so that with the lifting and lowering of the piston member, the charging and discharging of the oil between the first accumulator and the first cavity is synchronized with the charging and discharging of the oil between the second accumulator and the second cavity in an equal volume;

when the pressure of the first accumulator is not equal to the pressure of the second accumulator, the lift of the piston member triggers the valve assembly to open only the compensation oil circuit, so that with the lifting of the piston member, the oil is input into the first chamber from the third chamber, and the lowering of the piston member triggers the valve assembly to open only the first oil circuit or the second oil so that with the descending of the piston member, the oil is input into a low-pressure accumulator from the first chamber, wherein the low-pressure accumulator is the accumulator with a lower pressure among the first accumulator and the second accumulator.
The system of claim 1, characterized in that, the valve assembly comprises a one-way valve and a reversing valve, wherein the one-way valve is used to control the unidirectional flow of oil in each oil circuit in the system, and the reversing valve is used to switch the various oil circuits in the system.
The system of claim 2, characterized in that, the one-way valve comprises a compensation one-way valve disposed in the compensation oil passage, and the oil flow direction of the compensation one-way valve is from the third cavity to the first cavity.
The system of claim 2, characterized in that, the one-way valve comprises a second one-way valve disposed in the second oil circuit, and the oil flow direction of the second one-way valve is from the first cavity to the second accumulator.
The system of claim 4, characterized in that, the one-way valve further comprises a first one-way valve disposed in the first oil circuit, wherein a liquid inlet end of the second one-way valve is connected to the liquid inlet end of the one-way valve, and the oil flow direction of the first one-way valve is from the first cavity to the first accumulator.
The system of claim 2, characterized in that, the reversing valve comprises a hydraulic reversing valve for detecting the pressure of the first accumulator and the pressure of the second accumulator, and switch the oil circuit under the action of the pressure of the first accumulator and the pressure of the second accumulator.
The system of claim 6, characterized in that, the main port of the hydraulic reversing valve is communicated with the first cavity, and the first branch port of the hydraulic reversing valve is communicated with the first accumulator to form the target oil circuit, the second branch port of the hydraulic reversing valve is simultaneously communicated to the first accumulator and the second accumulator to form the first oil circuit and the second oil circuit;
wherein, when the pressure of the first accumulator is equal to the pressure of the second accumulator, the main port is only communicated with the first branch port;

wherein, when the pressure of the first accumulator is not equal to the pressure of the second accumulator, the main port is only communicated with the second branch port.
The system of claim 1, characterized in that, the initial pressure of the first accumulator is equal to the initial pressure of the second accumulator.
The system of claim 1, characterized in that, the axial cross-section side of the first cavity is convex, the axial cross-section of the second cavity is in the shape of two symmetrically separated steps, and the third cavity includes a fourth cavity and a fifth cavity that communicate with each other, the axial section of the fourth cavity is in the shape of two symmetrically separated inverted steps, and the axial section of the fifth cavity is in the form of two symmetrically separated rectangles;
The first cavity is located in the center of the hollow area surrounded by the shell, the second cavity is attached to the first cavity and is located at the lower part of the hollow area, and the fourth cavity is matched with the second cavity and is attached to the first cavity and is arranged on the upper part of the hollow area, and the fifth cavity is matched with the table provided by the second cavity and is attached to the fourth cavity and is arranged on the periphery of the hollow area.
The system of claim 9, characterized in that, an area of the piston member acting on the fourth cavity is equal to an area of the piston member acting on the fifth cavity.