A hydraulic system with oil leakage protection, a working machine and a method for oil leakage protection

Abstract

This invention discloses a hydraulic system for oil leakage protection, engineering machinery, and a method for oil leakage protection, relating to the field of hydraulic technology. The hydraulic system for oil leakage protection includes: a main oil circuit with an inlet and an outlet, and a sequence valve and a pressure comparison on-off valve connected in series between the inlet and outlet; a speed control valve, the inlet of which is connected between the inlet of the main oil circuit and the sequence valve; an accumulator delay unit, the inlet of which is connected to the outlet of the speed control valve, and the outlet of which is connected to the return oil tank; and a normally closed control terminal of the pressure comparison on-off valve connected to the inlet of the accumulator delay unit, and a normally open control terminal of which is connected to the inlet of the oil-requiring device. In practical use, when an oil leakage occurs in the oil-requiring device, the hydraulic system for oil leakage protection provided by this invention can promptly control the pressure comparison on-off valve to switch to the off position, stopping the oil supply to the oil-requiring device and preventing damage to the working oil pump due to oil shortage.

Description

Technical Field

[0001] This invention relates to the field of hydraulic technology, and more specifically, to a hydraulic system for preventing oil leakage. Furthermore, this invention also relates to engineering machinery including the aforementioned hydraulic system for preventing oil leakage, and a method for preventing oil leakage. Background Technology

[0002] In the current technology, in order to solve the problem of construction in hazardous working environments, many equipment now adopt beyond-line-of-sight remote control operation. Since the operators cannot operate the construction machinery on-site and only perceive and operate through video images, the poor field of vision and environmental awareness often lead to equipment collisions, resulting in exposed oil pipe ruptures and oil leaks or sprays. The operators cannot detect this in real time and stop the machine in time. If the oil leak lasts for a long time, the hydraulic system of the equipment will be damaged due to lack of oil, resulting in irreparable economic losses to the user. At the same time, the leaked oil pollutes the soil and damages the environment.

[0003] In summary, how to provide a hydraulic system for oil leakage protection that can promptly cut off oil supply in the event of a rupture and oil leak is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a hydraulic system for oil leakage protection. When an oil-demanding device leaks oil, the pressure at the normally open control end of the pressure comparison on-off valve decreases to less than the pressure at the normally closed control end, and the pressure comparison on-off valve switches to the off position to stop the oil supply to the oil-demanding device in time, so as to avoid damage to the working oil pump due to lack of oil.

[0005] Another objective of this invention is to provide an engineering machine including the above-mentioned oil leakage protection hydraulic system and an oil leakage protection method applied to the oil leakage protection hydraulic system.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A leak-protected hydraulic system, comprising:

[0008] The main oil circuit is provided with an oil inlet for connecting to an oil source and an oil outlet for connecting to an oil demand device. A sequence valve and a pressure comparison on / off valve are connected in series between the oil inlet and the oil outlet.

[0009] Speed ​​control valve, wherein the oil inlet of the speed control valve is connected between the oil inlet of the main oil circuit and the sequence valve;

[0010] A liquid accumulator delay device, wherein the oil inlet of the liquid accumulator delay device is connected to the oil outlet of the speed control valve, and the oil outlet of the liquid accumulator delay device is connected to the return oil tank;

[0011] The normally closed control terminal of the pressure comparison on-off valve is connected to the oil inlet terminal of the liquid storage delay device, and the normally open control terminal of the pressure comparison on-off valve is connected to the oil inlet terminal of the oil demand device. When the force of the normally closed control terminal is greater than the force of the normally open control terminal, the pressure comparison on-off valve switches to the closed position and stops supplying oil to the oil demand device. When the force of the normally closed control terminal is less than the force of the normally open control terminal, the pressure comparison on-off valve switches to the normally open position and supplies oil to the oil demand device.

[0012] Optionally, the first working area of ​​the normally open control terminal of the pressure comparison on / off valve is greater than the second working area of ​​the normally closed control terminal.

[0013] Optionally, the minimum set flow rate of the speed regulating valve is less than or equal to the flow rate at the inlet of the main oil circuit.

[0014] Optionally, the pressure comparison on / off valve is equipped with a first reset spring.

[0015] Optionally, a second reset spring is provided inside the liquid storage delay device, and the opening pressure of the sequence valve is greater than the second elastic pressure of the second reset spring, while the second elastic pressure of the second reset spring is less than the first elastic pressure of the first reset spring.

[0016] An engineering machine, comprising the oil leakage protection hydraulic system described in any one of the above claims.

[0017] An oil leakage protection method, applied to the oil leakage protection hydraulic system described in any one of the above claims, the oil leakage protection method comprising:

[0018] Determine whether the force at the normally open control end of the pressure comparison on-off valve is greater than the force at the normally closed control end of the pressure comparison on-off valve. If so, control the pressure comparison on-off valve to maintain it in the normally open position to supply oil to the oil-requiring device.

[0019] If not, the pressure comparison on / off valve is switched to the off position to stop supplying oil to the oil-requiring device.

[0020] In the process of using the oil leakage protection hydraulic system provided by this invention, when the oil source is first connected, the oil flows in from the inlet of the main oil circuit. Part of the hydraulic oil enters the accumulator delay unit through the speed regulating valve, and the remaining hydraulic oil opens the sequence valve and enters the pressure comparison on / off valve. During this process, because the pressure at the inlet of the accumulator delay unit is relatively small, the force of the normally closed control end of the pressure comparison on / off valve is less than the force of the normally open control end. The pressure comparison on / off valve switches to the normally open position to supply oil to the oil-requiring device. The oil-requiring device builds up working pressure under the continuous oil supply from the main oil circuit. The built-up working pressure then acts on the normally open end of the pressure comparison on / off valve, further ensuring that the force of the normally closed control end of the pressure comparison on / off valve is less than the force of the normally open control end, so that the main oil circuit can continuously supply oil to the oil-requiring device. When the accumulator delay unit has completed accumulating, the speed regulating valve becomes statically connected with no oil flow, and the accumulator delay... The pressure at the inlet of the device becomes the pressure at the inlet of the main oil circuit. At this time, although the pressure at the normally closed control end of the pressure comparison valve increases, because the first acting area of ​​the normally open control end of the pressure comparison valve is larger than the second acting area of ​​the normally closed control end, the force of the normally closed control end of the pressure comparison valve is less than the force of the normally open control end when there is pressure at the normally open control end of the pressure comparison valve, so that the main oil circuit can continuously supply oil to the oil-demanding device. When the oil-demanding device leaks oil, the oil outlet of the main oil circuit is depressurized, causing the pressure at the normally open control end of the pressure comparison valve to decrease. At this time, the accumulator delay device completes accumulating liquid, and the pressure at the normally closed control end of the pressure comparison valve becomes the pressure at the inlet of the main oil circuit. The force of the normally closed control end is greater than the force of the normally open control end, and the pressure comparison valve switches to the closed position, stopping the oil supply to the oil-demanding device.

[0021] Compared to existing technologies, the oil leakage protection hydraulic system provided by this invention can promptly control the pressure comparison on / off valve to switch to the off position and stop supplying oil to the oil-demanding device when an oil leakage occurs during actual use, thus preventing damage to the working oil pump due to lack of oil.

[0022] In addition, the present invention also provides an engineering machine including the above-mentioned oil leakage protection hydraulic system and an oil leakage protection method applied to the oil leakage protection hydraulic system. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a specific embodiment of the oil leakage protection hydraulic system provided by the present invention.

[0025] Figure 1 middle:

[0026] 1 is a speed control valve, 2 is a sequence valve, 3 is a pressure comparison on / off valve, and 4 is a liquid storage delay device. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The core of this invention is to provide a hydraulic system for oil leakage protection. When an oil-demanding device leaks oil, the pressure at the normally open control end of the pressure comparison on-off valve decreases until the force at the normally open control end is less than the force at the normally closed control end. The pressure comparison on-off valve then switches to the off position, promptly stopping the oil supply to the oil-demanding device and preventing damage to the working oil pump due to oil shortage.

[0029] Another objective of this invention is to provide an engineering machine including the above-mentioned oil leakage protection hydraulic system and an oil leakage protection method applied to the oil leakage protection hydraulic system.

[0030] Please refer to Figure 1 .

[0031] This specific embodiment discloses a hydraulic system for oil leakage protection, including: a main oil circuit, provided with an oil inlet for connection to an oil source and an oil outlet for connection to an oil-requiring device, wherein a sequence valve 2 and a pressure comparison on / off valve 3 are connected in series between the oil inlet and the oil outlet; a speed regulating valve 1, the oil inlet end of which is connected between the oil inlet end of the main oil circuit and the sequence valve 2; and a liquid accumulator delay unit 4, the oil inlet end of which is connected to the oil outlet end of the speed regulating valve 1, wherein the liquid accumulator delay unit 4... The oil outlet is connected to the return oil tank; the normally closed control end of the pressure comparison on-off valve 3 is connected to the oil inlet end of the liquid accumulator delay device 4, and the normally open control end of the pressure comparison on-off valve 3 is connected to the oil inlet end of the oil demand device. When the force of the normally closed control end is greater than the force of the normally open control end, the pressure comparison on-off valve 3 switches to the closed position and stops supplying oil to the oil demand device. When the force of the normally closed control end is less than the force of the normally open control end, the pressure comparison on-off valve 3 switches to the normally open position and supplies oil to the oil demand device.

[0032] In this specific embodiment, the speed control valve 1 is used to provide a stable flow rate and prevent the flow rate from being affected by changes in pressure before and after. When the pressure difference is constant, the flow rate through the speed control valve 1 is proportional to the flow area of ​​the throttle valve. A larger throttle area results in a larger flow rate, and vice versa. After the throttle valve area is adjusted, the flow rate is basically constant. The sequence valve 2 is used to generate a pressure threshold. This pressure threshold acts on the normally closed control end of the pressure comparison on / off valve 3 and is compared with the spring pressure of the normally open control end and the sum of the pressure after the valve. When the force of the normally closed control end is greater than the force of the normally open control end, the pressure comparison on / off valve 3 switches. The pressure comparison on / off valve 3 is used to switch accordingly based on the pressure comparison at its control port. The accumulator delay timer 4 is used to delay the pressure at the inlet of the main oil circuit for a certain period of time when the oil source is first connected, so that it acts on the normally closed control end of the pressure comparison on / off valve 3.

[0033] In the specific setup process, the first working area of ​​the normally open control end of the pressure comparison on-off valve 3 can be made larger than the second working area of ​​the normally closed control end. Here, the first working area refers to the cross-sectional area of ​​the valve core of the pressure comparison on-off valve 3 at the normally open control end, and the second working area refers to the cross-sectional area of ​​the valve core of the pressure comparison on-off valve 3 at the normally closed control end. The difference between the first and second working areas can be determined according to actual needs during the design process. It must be ensured that when the working pressure of the normally closed end of the pressure comparison on-off valve 3 is the inlet pressure of the main oil circuit, the working force of the normally closed end of the pressure comparison on-off valve 3 is less than the working force of the normally open end; and when leakage occurs at the normally open end of the pressure comparison on-off valve 3, the working force of the normally closed end of the pressure comparison on-off valve 3 is greater than the working force of the normally open end.

[0034] In the process of using the oil leakage protection hydraulic system provided in this specific embodiment, when the oil source is first connected, the oil source flows in from the oil inlet of the main oil circuit. Part of the hydraulic oil enters the accumulator delay 4 through the speed regulating valve 1, and the remaining hydraulic oil opens the sequence valve 2 and enters the pressure comparison on / off valve 3. During this process, because the pressure at the oil inlet of the accumulator delay 4 is relatively small, the force of the normally closed control end of the pressure comparison on / off valve 3 is less than the force of the normally open control end. The pressure comparison on / off valve 3 switches to the normally open position to supply oil to the oil-requiring device. The oil-requiring device builds up working pressure under the continuous oil supply of the main oil circuit. The built-up working pressure then acts on the normally open end of the pressure comparison on / off valve 3, further ensuring that the force of the normally closed control end of the pressure comparison on / off valve 3 is less than the force of the normally open control end, so that the main oil circuit can continuously supply oil to the oil-requiring device. When the accumulator delay 4 has finished accumulating, the speed regulating valve 1 becomes statically connected with no oil flow. When the pressure at the inlet of the liquid delay timer 4 becomes the pressure at the inlet of the main oil circuit, although the pressure at the normally closed control end of the pressure comparison on-off valve 3 increases, the first acting area of ​​the normally open control end of the pressure comparison on-off valve 3 is larger than the second acting area of ​​the normally closed control end. Therefore, even with pressure at the normally open control end of the pressure comparison on-off valve 3, the force exerted by the normally closed control end is less than the force exerted by the normally open control end, allowing the main oil circuit to continuously supply oil to the oil-demanding device. When the oil-demanding device leaks oil, the outlet of the main oil circuit depressurizes, causing the pressure at the normally open control end of the pressure comparison on-off valve 3 to decrease. At this time, the liquid delay timer 4 completes liquid storage, and the pressure at the normally closed control end of the pressure comparison on-off valve 3 becomes the pressure at the inlet of the main oil circuit. Since the force exerted by the normally closed control end is greater than the force exerted by the normally open control end, the pressure comparison on-off valve 3 switches to the off position, stopping the oil supply to the oil-demanding device.

[0035] Compared to existing technologies, the oil leakage protection hydraulic system provided in this specific embodiment can promptly control the pressure comparison on / off valve 3 to switch to the off position and stop supplying oil to the oil-demanding device when an oil leakage occurs during actual use, thus preventing damage to the working oil pump due to lack of oil.

[0036] In one specific embodiment, the first working area of ​​the normally open control end of the pressure comparison on / off valve 3 is greater than the second working area of ​​the normally closed control end. The difference between the first working area and the second working area needs to be determined according to the actual situation. However, it is necessary to ensure that after the liquid storage delay device 4 has completed the liquid storage, the force of the normally closed control end of the pressure comparison on / off valve 3 is less than the force of the normally open control end, so that the main oil circuit can continuously supply oil to the oil-demanding device.

[0037] Preferably, the minimum set flow rate of the speed control valve 1 is less than or equal to the flow rate at the inlet of the main oil circuit. The minimum set flow rate of the speed control valve 1 can be denoted as Qmin, the flow rate at the inlet of the main oil circuit is Q, the opening pressure of the sequence valve 2 is P1, the compensation pressure difference of the speed control valve 11 is ΔP, the first elastic pressure of the first return spring in the pressure comparison on-off valve 3 is P0, and P1≥ΔP, P1≥P0; a second return spring is provided in the liquid storage delay device 4, and the second elastic pressure P2 of the second return spring is less than the first elastic pressure P0 of the first return spring. The variable volume of the liquid storage delay device 4 is V, and the time for each oil source connection and liquid filling completion is t = V / Qmin.

[0038] When the equipment is just connected to the oil source, the oil from the oil source flows into the inlet. Since its flow rate Q is greater than or equal to the minimum set flow rate Qmin of the speed control valve 1, the excess oil opens the sequence valve 2, flows through the normally open position of the pressure comparison on-off valve 3 and is supplied to the external oil-requiring device from the outlet. The flow rate through the speed control valve 1 overcomes the second elastic pressure P2 of the second return spring of the liquid storage delay device 4 and fills the liquid storage delay device 4. The liquid filling time t of the liquid storage delay device 4 is t = V / Qmin. During the liquid filling process, the liquid filling pressure remains basically unchanged and acts on the normally closed control end of the pressure comparison on-off valve 3. Since P2 < P0, the pressure comparison on-off valve 3 remains in the normally open position. The external oil-requiring device starts to establish the working pressure under the continuous oil supply of the main oil circuit. The established working pressure acts on the normally open control end of the pressure comparison on-off valve 3 in a feedback manner to ensure that the pressure comparison on-off valve 3 is in the normally open position. After a period of time t, the liquid storage delay device 4 is filled, the speed control valve 1 has no oil flow and becomes a static connection, and the liquid filling pressure of the liquid storage delay device 4 instantly becomes the oil supply pressure at the inlet of the main oil circuit. The pressure at the normally closed control end of the pressure comparison on-off valve 3随之 becomes the oil supply pressure at the inlet of the main oil circuit. Although the pressure acting on the normally closed control end of the pressure comparison on-off valve 3 increases at this time, since the first acting area of the normally open control end of the pressure comparison on-off valve 3 is larger than the second acting area of the normally closed control end, by designing the difference between the first acting area and the second acting area, it can be ensured that the pressure comparison on-off valve 3 remains in the normally open position and continues to supply oil to the external oil-requiring device.

[0039] After the equipment is working normally, if the external oil-requiring device experiences pipeline damage and oil leakage, the pressure at the main oil outlet will suddenly decrease, causing the pressure at the normally open control end of the pressure comparison valve 3 to decrease. The normally open control end is only subject to the first elastic pressure P0 of the first reset spring. At the same time, the oil inlet of the main oil circuit drops to the opening pressure P1 set by the sequence valve 2. Since the accumulator delay 4 has completed filling, the speed control valve 1 remains statically connected without oil flow. The filling pressure of the accumulator delay 4 instantly becomes the oil supply pressure at the oil inlet. Therefore, the pressure at the normally closed control end of the pressure comparison valve 3 also becomes P1. Since P1≥P0, the pressure comparison valve 3 switches to the closed position, cutting off the oil supply to the external oil-requiring device, thereby preventing further oil leakage and effectively protecting the equipment.

[0040] In addition to the aforementioned oil leakage protection hydraulic system, the present invention also provides an engineering machinery including the oil leakage protection hydraulic system disclosed in the above embodiments. For the structure of other parts of the engineering machinery, please refer to the prior art, which will not be repeated here.

[0041] In addition to the aforementioned oil leakage protection hydraulic system, the present invention also provides an oil leakage protection method applied to the oil leakage protection hydraulic system disclosed in the above embodiments, the oil leakage protection method comprising:

[0042] Step S1: Determine whether the pressure at the normally open control end of the pressure comparison on-off valve 3 is greater than the pressure at the normally closed control end of the pressure comparison on-off valve 3. If so, control the pressure comparison on-off valve 3 to maintain the normally open position to supply oil to the oil-requiring device.

[0043] Step S2: If not, control the pressure comparison valve 3 to switch to the off position to stop supplying oil to the oil-requiring device.

[0044] The terms "first" and "second" in the first and second reset springs mentioned in this application are merely to distinguish their different positions and do not indicate any order of priority.

[0045] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Any combination of all embodiments provided by this invention is within the scope of protection of this invention and will not be elaborated upon here.

[0046] The oil leakage protection hydraulic system, engineering machinery, and oil leakage protection method provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A hydraulic system for preventing oil leakage, characterized in that, include: The main oil circuit is provided with an oil inlet for connecting to an oil source and an oil outlet for connecting to an oil demand device. A sequence valve (2) and a pressure comparison on / off valve (3) are connected in series between the oil inlet and the oil outlet. Speed ​​control valve (1), the oil inlet end of the speed control valve (1) is connected between the oil inlet of the main oil circuit and the sequence valve (2); The oil inlet of the oil storage delay device (4) is connected to the oil outlet of the speed control valve (1), and the oil outlet of the oil storage delay device (4) is connected to the return oil tank. The normally closed control end of the pressure comparison on / off valve (3) is connected to the oil inlet end of the liquid storage delay device (4), and the normally open control end of the pressure comparison on / off valve (3) is connected to the oil inlet end of the oil demand device. When the force of the normally closed control end is greater than the force of the normally open control end, the pressure comparison on / off valve (3) switches to the off position and stops supplying oil to the oil demand device. When the force of the normally closed control end is less than the force of the normally open control end, the pressure comparison on / off valve (3) switches to the normally open position and supplies oil to the oil demand device. The minimum set flow rate of the speed regulating valve (1) is less than or equal to the flow rate of the oil inlet of the main oil circuit; The pressure comparison on / off valve (3) is provided with a first reset spring; the liquid storage delay device (4) is provided with a second reset spring, the opening pressure of the sequence valve (2) is greater than the second elastic pressure of the second reset spring, and the second elastic pressure of the second reset spring is less than the first elastic pressure of the first reset spring; The minimum set flow rate of the speed regulating valve (1) is less than or equal to the flow rate of the inlet of the main oil circuit; the opening pressure of the sequence valve (2) is P1, the compensation pressure difference of the speed regulating valve (1) is ΔP, the first elastic pressure of the first return spring in the pressure comparison on / off valve (3) is P0, and P1≥ΔP, P1≥P0; the second elastic pressure P2 of the second return spring is less than the first elastic pressure P0 of the first return spring.

2. The oil leakage protection hydraulic system according to claim 1, characterized in that, The first working area of ​​the normally open control terminal of the pressure comparison on / off valve (3) is greater than the second working area of ​​the normally closed control terminal.

3. An engineering machinery, characterized in that, The oil leakage protection hydraulic system as described in any one of claims 1-2.

4. A method for preventing oil leaks, characterized in that, The oil leakage protection method is applied to the oil leakage protection hydraulic system according to any one of claims 1-2, wherein the oil leakage protection method comprises: Determine whether the pressure at the normally open control end of the pressure comparison on / off valve (3) is greater than the pressure at the normally closed control end of the pressure comparison on / off valve (3). If so, control the pressure comparison on / off valve (3) to remain in the normally open position to supply oil to the oil-requiring device. If not, control the pressure comparison on / off valve (3) to switch to the off position and stop supplying oil to the oil-requiring device.

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