Hydraulic control system and method for a bulldozer

Abstract

This invention relates to the field of bulldozer technology and provides a hydraulic control system and method for bulldozers. It recovers the energy generated by the descent of the bulldozer's working device through an accumulator. When the working device is lifted or other mechanisms require hydraulic pressure, a solenoid valve is opened. A solenoid proportional valve opens its valve core according to the compensation flow required by the second inlet valve. The oil in the accumulator provides a corresponding flow rate according to the opening degree of the solenoid proportional valve. The solenoid proportional valve sends the hydraulic oil from the accumulator through a first check valve to the inlet of the second inlet valve. The solenoid valve receives a compensation signal and opens the oil outlet passage of the accumulator. The hydraulic energy stored in the accumulator, after being regulated by the control terminal of the solenoid proportional valve, is then delivered through the first check valve to the inlet of the second inlet valve and subsequently enters the lifting chamber of the lifting cylinder. This compensates for the lifting of the blade, achieving stable and controllable oil flow and ensuring smooth movement of the working device or other actuators.

Description

Technical Field

[0001] This invention relates to the field of bulldozer technology, and more specifically, to a hydraulic control system and method for bulldozers. Background Technology

[0002] Bulldozers are a common type of construction machinery, and one of their core functions is raising and lowering the working device during operation. Bulldozers typically use a hydraulic system for raising and lowering, with hydraulic cylinders used to lift and lower the working device.

[0003] Currently, due to the large mass of the working device, if the descent speed of the hydraulic cylinder is not controlled during the descent process, the working device will experience uncontrolled free fall, which will affect the safety and accuracy of the operation. Existing bulldozers usually have a throttling device installed at the descent valve core of the working device to slow down its descent speed.

[0004] However, using an accumulator as an energy-saving device to recover the energy during the descent of the working device, the accumulator stores and releases energy to control the descent process. However, directly connecting the accumulator to the hydraulic system and replenishing the system with pressurized oil can lead to a decrease in system stability due to the instantaneous high pressure and large flow, and may even cause a sudden increase in the speed of the actuator.

[0005] To address the above problems, this invention proposes a hydraulic control system and method for bulldozers. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a hydraulic control system and method for bulldozers.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A hydraulic control system for a bulldozer includes a lifting cylinder. A second inlet valve and a second check valve are connected to the lifting cylinder. The second inlet valve is also connected to the second check valve. An accumulator and a solenoid valve are connected to the second check valve. The solenoid valve is connected to the accumulator. An electromagnetic proportional valve is also connected to the solenoid valve. The other end of the electromagnetic proportional valve is connected to a first check valve. One end of both the first check valve and the second inlet valve is connected to an oil suction pump. The other end of the oil suction pump is connected to an oil tank. The second inlet valve is also connected to the oil tank, forming a return oil channel.

[0009] The present invention is further configured such that: a first oil inlet valve is also connected to the second oil inlet valve, an auxiliary oil cylinder is connected to the other end of the first oil inlet valve, and the first oil inlet valve is also connected to an oil tank.

[0010] The present invention is further configured such that: the auxiliary cylinder includes an auxiliary large chamber and an auxiliary small chamber, both of which are connected to a first oil inlet valve.

[0011] The present invention is further configured such that: the lifting cylinder includes a large lifting chamber and a small lifting chamber, both of which are connected to a second oil inlet valve, and the second oil inlet valve is also connected to an oil tank.

[0012] The present invention is further configured such that: a pressure compensation valve is connected in parallel to both ends of the electromagnetic proportional valve, and an overflow valve is also connected to one end of the accumulator, and the other end of the overflow valve is connected to the oil tank.

[0013] A hydraulic control method for a bulldozer, wherein the system is applied in the aforementioned hydraulic control system for a bulldozer, the system comprising:

[0014] Step S1: The bulldozer hydraulic control system collects the bulldozer's control requirements and determines whether it is blade lifting control. If yes, proceed to step S2; otherwise, proceed to step S3.

[0015] Step S2: The bulldozer enters the blade lifting control mode;

[0016] Step S3: The bulldozer enters the blade descent control mode;

[0017] Step S4: Monitor the accumulator pressure. When the accumulator pressure is detected to be higher than the preset value, depressurize.

[0018] The present invention is further configured such that step S2 includes:

[0019] Step S21: The solenoid valve is energized and turned on, opening the oil circuit from the accumulator to the pressure compensation valve. The pressure compensation valve automatically adjusts according to the pressure difference between the inlet and outlet of the solenoid proportional valve to ensure that the flow rate is proportional to the valve opening.

[0020] Step S22: Based on the bulldozer's lifting speed requirements, monitor the current flow rate of the accumulator, calculate the compensation flow rate required for the second oil inlet valve through the controller, and generate the corresponding electromagnetic proportional valve control current based on the compensation flow rate required for the second oil inlet valve.

[0021] The present invention is further configured such that step S2 also includes:

[0022] Step S23: The electromagnetic proportional valve opens according to the current opening degree. The pressure compensation valve monitors the pressure difference between the inlet and outlet of the electromagnetic proportional valve in real time and automatically adjusts the valve core position to ensure that the flow through the electromagnetic proportional valve is only proportional to its opening degree and is not affected by the pressure fluctuation of the accumulator and the change of system load.

[0023] In step S24, the oil released from the accumulator passes through the electromagnetic proportional valve and the first check valve, and then merges with the pressurized oil output by the suction pump in the pipeline.

[0024] The present invention is further configured such that step S3 includes:

[0025] In step S31, the second oil inlet valve switches to the lowering working position, and the pressure oil output by the oil suction pump enters the large lifting chamber of the lifting cylinder, while the small lifting chamber begins to return oil.

[0026] In step S32, the hydraulic oil discharged from the lifting chamber flows into the accumulator through the working port of the second inlet valve and the second check valve, converting the potential energy of the shovel's descent into hydraulic energy and storing it in the accumulator.

[0027] The present invention is further configured such that step S3 also includes:

[0028] In step S33, the accumulator pressure increases as the liquid is filled, creating back pressure on the lifting chamber, thereby limiting the descent speed and preventing the blade from falling freely.

[0029] In step S34, when the blade descends to the target position, the second oil inlet valve returns to the neutral position, ending the descent mode. At this time, the accumulator has stored energy, which will be released during the next lifting.

[0030] In summary, this application includes at least one of the following beneficial technical effects:

[0031] The energy generated by the descent of the bulldozer's working device is recovered through an accumulator. When the working device is lifted or other mechanisms require hydraulic pressure, the solenoid valve is opened, and the solenoid proportional valve opens its valve core as needed. The oil in the accumulator provides a corresponding flow rate of oil according to the opening degree of the solenoid proportional valve. The solenoid proportional valve sends the hydraulic oil in the accumulator to the inlet of the second inlet valve after passing through the first check valve. The solenoid valve receives a compensation signal and opens the oil outlet passage of the accumulator. The hydraulic energy stored in the accumulator is regulated by the control end of the solenoid proportional valve and then sent to the inlet of the second inlet valve through the first check valve. It then enters the lifting chamber of the lifting cylinder to compensate for the lifting of the blade, thereby stabilizing and controlling the oil flow and ensuring the smooth movement of the working device or other actuators. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of a hydraulic control system for a bulldozer according to the present invention.

[0033] Figure 2 This is a schematic diagram of the system structure of a hydraulic control method for bulldozers according to the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. First check valve; 2. Electromagnetic proportional valve; 3. Pressure compensation valve; 4. Solenoid valve; 5. Relief valve; 6. Accumulator; 7. Second check valve; 8. Auxiliary cylinder; 81. Auxiliary large chamber; 82. Auxiliary small chamber; 9. Lifting cylinder; 91. Lifting large chamber; 92. Lifting small chamber; 10. First inlet valve; 11. Second inlet valve; 12. Suction pump; 13. Oil tank. Detailed Implementation

[0036] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0037] It should be noted that when a component is referred to as "connected to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0040] Throughout this specification, reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of this application. Therefore, the phrases "in one embodiment," "in some embodiments," or "in some of these embodiments" appear in various places throughout the specification, and not all refer to the same embodiment. Furthermore, in one or more embodiments, a particular feature, structure, or characteristic may be combined in any suitable manner.

[0041] Please see Figure 1-2 The present invention provides the following technical solutions:

[0042] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0043] See Figure 1 This invention discloses a hydraulic control system for bulldozers, mainly used for hydraulic control and energy recovery of the working device of bulldozers and other construction machinery. The system includes: a lifting cylinder 9, a second inlet valve 11 and a second check valve 7 connected to the lifting cylinder 9, the second inlet valve 11 also connected to the second check valve 7, an accumulator 6 and a solenoid valve 4 connected to the second check valve 7, the solenoid valve 4 connected to the accumulator 6, an electromagnetic proportional valve 2 connected to the solenoid valve 4, the other end of the electromagnetic proportional valve 2 connected to a first check valve 1, one end of the first check valve 1 and the second inlet valve 11 both connected to an oil suction pump 12, the other end of the oil suction pump 12 connected to an oil tank 13, and the second inlet valve 11 also communicating with the oil tank 13 to form a return oil channel.

[0044] The oil inlet of the oil suction pump 12 is connected to the oil tank 13, and the oil outlet of the oil suction pump 12 is connected to the oil outlet of the first check valve 1 and the oil inlet of the second inlet valve 11 respectively. The oil suction pump 12 draws hydraulic oil from the oil tank 13, sends the hydraulic oil to the oil outlet of the oil suction pump 12, and then sends it from the oil outlet of the oil suction pump 12 to the oil inlet of the second inlet valve 11.

[0045] The lifting cylinder 9 includes a large lifting chamber 91 and a small lifting chamber 92, both of which are connected to the second inlet valve 11. When the bulldozer performs blade lowering operations, the second inlet valve 11 controls the hydraulic oil to enter the large lifting chamber 91. The hydraulic oil discharged from the small lifting chamber 92 enters the accumulator 6 through the second check valve 7 for energy recovery. The second check valve 7 ensures that the oil can only flow from the small chamber to the accumulator 6, converting the potential energy of the blade lowering into hydraulic energy stored in the accumulator 6. When the bulldozer performs blade lifting operations, the second inlet valve 11 switches the oil circuit, the solenoid valve 4 receives the lifting compensation signal, and the oil output from the accumulator 6 enters the inlet of the second inlet valve 11 through the first check valve 1. The solenoid proportional valve 2 controls the output flow of the accumulator 6 to achieve precise pressure and flow regulation of the lifting action.

[0046] The oil inlet of the first check valve 1 is connected to the electromagnetic proportional valve 2. The electromagnetic proportional valve 2 is connected to the electromagnetic valve 4. The electromagnetic valve 4 is connected to the oil inlet of the accumulator 6 and the second check valve 7, respectively. The oil inlet of the second check valve 7 is connected to a working port of the second oil inlet valve 11 and is connected to the lifting chamber 92 of the lifting cylinder 9.

[0047] The electromagnetic proportional valve 2 sends the hydraulic oil in the accumulator 6 through the first check valve 1 to the inlet of the second inlet valve 11. The electromagnetic valve 4 receives the compensation signal and opens the oil outlet passage of the accumulator 6, so that the hydraulic energy stored in the accumulator 6 is regulated by the control end of the electromagnetic proportional valve 2 and then sent through the first check valve 1 to the inlet of the second inlet valve 11, and then enters the lifting chamber 92 of the lifting cylinder 9 to achieve compensation for the lifting of the blade.

[0048] During this process, the current of the electromagnetic proportional valve 2 determines the amount of flow released by the accumulator 6, thereby controlling the lifting speed. When rapid lifting is required, the current is increased to fully open the valve, providing a large flow rate. When fine-tuning or slow lifting is required, the current is reduced to limit the flow rate. This control method allows the energy release from the accumulator 6 to be seamlessly integrated with the pump's output oil, improving lifting efficiency and ensuring smooth operation.

[0049] The second oil inlet valve 11 is also connected to the first oil inlet valve 10, and the other end of the first oil inlet valve 10 is connected to the auxiliary oil cylinder 8. The first oil inlet valve 10 is also connected to the oil tank 13.

[0050] The first check valve 1 and the second check valve 7 are used to prevent hydraulic oil from flowing backward. The electromagnetic proportional valve 2 is used to adjust the oil circuit pressure and flow rate according to the signals fed back by the second inlet valve 11 and the first inlet valve 10. The pressure compensation valve 3 is used to monitor the pressure difference across the electromagnetic proportional valve 2 and output a compensation signal to the control terminal of the electromagnetic proportional valve 2 to maintain a constant pressure difference across its valve port. The electromagnetic valve 4 is used to receive control signals and switch the oil circuit on and off. The overflow valve 5 is used to release excess hydraulic oil in the accumulator 6 to the oil tank 13. The auxiliary cylinder 8 is used to support other working devices on the bulldozer. The lifting cylinder 9 is used to realize the lifting and lowering action of the bulldozer blade. The first inlet valve 10 is used to control the oil inlet and return of the auxiliary cylinder 8. The second inlet valve 11 is used to control the oil inlet and return of the lifting cylinder 9. The suction pump 12 is used to draw oil from the oil tank 13 to provide a power source for the entire hydraulic system.

[0051] When there is a need for auxiliary device operation on the bulldozer, the oil inlet and return control of the auxiliary cylinder 8 is added to drive the operation of the auxiliary device. At the same time, the auxiliary cylinder 8 can also work in conjunction with the accumulator 6 to recover potential energy when the auxiliary device performs the lowering or retraction action, and release the stored energy when it performs the lifting or extension action, thereby reducing the energy consumption of the main system.

[0052] The return port of the second oil inlet valve 11 is connected to the oil tank 13. The auxiliary oil cylinder 8 includes an auxiliary large chamber 81 and an auxiliary small chamber 82, both of which are connected to the first oil inlet valve 10. The return port of the first oil inlet valve 10 is also connected to the oil tank 13.

[0053] The second inlet valve 11 is connected to the oil tank 13, which can directly return the hydraulic oil discharged from the lifting large chamber 91 to the oil tank 13, realizing undamped unloading during the rapid descent of the blade; the auxiliary large chamber 81 and the auxiliary small chamber 82 of the auxiliary cylinder 8 are respectively connected to the main oil circuit through the corresponding working oil port of the first inlet valve 10. When the auxiliary device performs the descent or retraction action, the hydraulic oil discharged from the auxiliary large chamber 81 flows back to the oil tank 13 through the first inlet valve 10, and the auxiliary small chamber 82 enters the hydraulic oil. When the auxiliary device performs the lifting or extension action, the hydraulic oil discharged from the auxiliary small chamber 82 flows back to the oil tank 13 through the first inlet valve 10, and the auxiliary large chamber 81 enters the hydraulic oil.

[0054] The bulldozer has auxiliary devices (such as rippers, tilting cylinders, etc.) that require operation. If the auxiliary cylinder 8 is connected to the hydraulic control system, the auxiliary chamber 82 of the auxiliary cylinder 8 is connected to the accumulator 6 through a separately provided check valve, so that the hydraulic oil discharged from the auxiliary chamber 82 flows into the accumulator 6 in one direction through the check valve for energy recovery. When the auxiliary device descends or retracts, the hydraulic oil discharged from the auxiliary chamber 82 flows into the accumulator 6 through the check valve for energy recovery. When the auxiliary device is raised or extended and requires energy, the hydraulic oil stored in the accumulator 6 is output to the first inlet valve 10 through the electromagnetic proportional valve 2 and the first check valve 1 to compensate for the oil supply to the auxiliary chamber 82 of the auxiliary cylinder 8, thereby reducing the energy consumption of the main pump.

[0055] When the working device needs to be lifted or other mechanisms need to move, solenoid valve 4 is energized, and the oil in accumulator 6 flows to the pressure compensation valve. At the same time, the solenoid proportional valve is opened. The solenoid proportional valve can precisely control the outflow of oil in accumulator 6 as needed, ensuring stable and controllable system flow.

[0056] When the auxiliary cylinder 8 does not require compensation from the accumulator 6, the oil pump 12 draws oil from the oil tank 13 and sends it to the inlet of the first oil inlet valve 10. According to the control requirements of the auxiliary cylinder 8, the first oil inlet valve 10 switches its working position, so that the hydraulic oil enters the auxiliary large chamber 81 or the auxiliary small chamber 82 through its corresponding working oil port, driving the auxiliary device to perform lifting or lowering actions.

[0057] A pressure compensation valve 3 is connected in parallel across both ends of the electromagnetic proportional valve 2. The inlet of the pressure compensation valve 3 is connected to the outlet of the electromagnetic valve 4, and the outlet is connected to the outlet of the electromagnetic proportional valve 2. Its control oil circuit is taken from the inlet and outlet of the electromagnetic proportional valve 2, respectively, to ensure that the flow rate through the electromagnetic proportional valve 2 is proportional to its opening degree.

[0058] To prevent the accumulator 6 from being charged with excessively high pressure, an overflow valve 5 is connected to one end of the accumulator 6. The outlet of the overflow valve 5 is connected to the oil tank 13, and the inlet of the overflow valve 5 is connected to the charging end of the accumulator 6. When the pressure inside the accumulator 6 exceeds its set pressure value, the overflow valve 5 opens to drain the excess hydraulic oil back to the oil tank 13, thereby limiting the maximum working pressure of the accumulator 6.

[0059] When rapid lifting or acceleration is required, the control program instantly increases the current of the electromagnetic proportional valve 2, causing the valve to fully open. The accumulator 6 then releases a large flow of oil to meet the instantaneous power demand. When fine-tuning or precise positioning is needed, the current is reduced to make the valve opening small, providing a stable small flow of oil to ensure operational accuracy. When the system does not require energy compensation, the electromagnetic valve 4 is de-energized to cut off the accumulator 6 circuit, preventing the pressure of the accumulator 6 from interfering with the main system. At the same time, the return ports of the second inlet valve 11 and the first inlet valve 10 are directly connected to the oil tank 13, enabling the blade or auxiliary device to descend rapidly without damping, further reducing energy consumption.

[0060] The energy generated by the descent of the bulldozer's working device is recovered through the accumulator 6. When the working device is lifted or other mechanisms require hydraulic pressure, the solenoid valve is opened, and the solenoid proportional valve 2 opens its valve core as required. The oil in the accumulator 6 will provide oil of a corresponding flow rate according to the opening degree of the solenoid proportional valve 2, regardless of the pressure of the hydraulic system. This achieves the effect of stabilizing and controlling the oil flow rate, ensuring the smooth movement of the working device or other actuators. Furthermore, the increase in the speed of the working device or other mechanisms is controlled by the magnitude of the current of the solenoid proportional valve 2. The magnitude of the current of the solenoid proportional valve 2 is determined according to the compensation amount required by the second oil inlet valve 11 and the first oil inlet valve 10. The compensation amount generates an electromagnetic signal and sends it to the solenoid proportional valve 2.

[0061] Based on the bulldozer's lifting requirements, the current flow rate of the accumulator 6 is monitored. The controller calculates the compensation flow rate required by the second oil inlet valve 11 and generates the corresponding control current for the electromagnetic proportional valve 2 based on the compensation flow rate required by the second oil inlet valve 11. The current of the electromagnetic proportional valve 2 is controlled by the control program to input different flow rates to the working device cylinder or other actuators under different working conditions. This allows the replenished oil to provide a large flow rate to the working device cylinder or other actuators instantly, or to provide a small flow rate to the working device cylinder or other actuators slowly for a long time. It can also provide oil to the working device cylinder or other actuators at a fast rate at the beginning and a slow rate at the end. By controlling the current of the electromagnetic proportional valve 2 to set the replenishment flow rate in any way according to the working conditions, the control performance of the working device or other actuators is improved, and the operating experience is enhanced.

[0062] See Figure 2 A hydraulic control method for a bulldozer, wherein the system is applied in the aforementioned hydraulic control system for a bulldozer, the system comprising:

[0063] Step S1: The bulldozer hydraulic control system collects the bulldozer's control requirements and determines whether it is blade lifting control. If yes, proceed to step S2; otherwise, proceed to step S3.

[0064] Specifically, the operator issues commands through the control lever in the bulldozer. If the command is to raise the blade, the system switches to S2, the blade raising control mode; if the command is to lower the blade, the system switches to S3, the blade lowering control mode.

[0065] If the command is for other auxiliary devices (such as a soil ripper or tilting cylinder), the auxiliary control program will be switched.

[0066] Step S2: The bulldozer enters the blade lifting control mode;

[0067] In step S21, the solenoid valve 4 is energized and turned on, opening the oil circuit from the accumulator 6 to the pressure compensation valve 3. The pressure compensation valve 3 automatically adjusts according to the pressure difference between the inlet and outlet of the solenoid proportional valve 2 to ensure that the flow rate is proportional to the valve opening.

[0068] Step S22: Based on the lifting speed requirements of the bulldozer, monitor the current flow rate of the accumulator 6, calculate the compensation flow rate required by the second oil inlet valve 11 through the controller, and generate the corresponding control current of the electromagnetic proportional valve 2 based on the compensation flow rate required by the second oil inlet valve 11.

[0069] In step S23, the electromagnetic proportional valve 2 opens according to the current opening degree. The pressure compensation valve 3 monitors the pressure difference between the inlet and outlet of the electromagnetic proportional valve 2 in real time and automatically adjusts the valve core position to ensure that the flow through the electromagnetic proportional valve is only proportional to its opening degree and is not affected by the pressure fluctuation of the accumulator 6 and the change of system load.

[0070] In step S24, the oil released by the accumulator 6 passes through the electromagnetic proportional valve 2 and the first check valve 1, and then merges with the pressurized oil output by the oil suction pump 12 in the pipeline.

[0071] In step S25, the second oil inlet valve 11 is switched to the lifting working position, and the combined pressure oil is sent into the lifting chamber 91 of the lifting cylinder 9 to push the piston out and realize the smooth lifting of the blade.

[0072] Step S26: When the blade reaches the target height, the solenoid valve 4 is de-energized and closes the accumulator 6 passage, the second oil inlet valve 11 returns to the neutral position, and the system exits the lifting mode.

[0073] Step S3: The bulldozer enters the blade descent control mode;

[0074] In step S31, the second oil inlet valve 11 is switched to the lowering working position, and the pressure oil output by the oil suction pump 12 enters the large lifting chamber 91 of the lifting cylinder 9, while the small lifting chamber 92 begins to return oil.

[0075] In step S32, the hydraulic oil discharged from the lifting chamber 92 flows into the accumulator 6 through the working port of the second inlet valve 11 and the second check valve 7, converting the potential energy of the shovel's descent into hydraulic energy and storing it in the accumulator 6.

[0076] In step S33, the pressure in accumulator 6 increases as it is filled with liquid, creating back pressure on the lifting chamber 92, thereby limiting the descent speed and preventing the blade from falling freely.

[0077] In step S34, when the blade descends to the target position, the second oil inlet valve 11 returns to the neutral position, ending the descent mode. At this time, the accumulator 6 has stored energy, which will be released during the next lifting.

[0078] Step S4: Monitor the pressure of accumulator 6. When the pressure of accumulator 6 is detected to be higher than the preset value, depressurize.

[0079] Step S41: The system monitors the pressure value of the accumulator 6 in real time;

[0080] Step S42: If the pressure is higher than the preset safety threshold, the overflow valve 5 will open automatically to release the excess hydraulic oil in the accumulator 6 into the oil tank 13 until the pressure drops back to the safe range.

[0081] In step S43, once the pressure returns to normal, the overflow valve 5 automatically closes, maintaining the energy storage state of the accumulator 6.

[0082] When the bulldozer requires auxiliary devices (such as rippers, tilting cylinders, etc.), the system automatically enters the auxiliary control subroutine: the controller controls the first oil inlet valve 10 to switch working positions according to the operation command, so that hydraulic oil enters the auxiliary large chamber 81 or auxiliary small chamber 82 of the auxiliary cylinder 8, driving the auxiliary device to perform the corresponding action; if the auxiliary device performs a lowering or retracting action, the hydraulic oil discharged from the auxiliary small chamber 82 flows into the accumulator 6 through the check valve for energy recovery, converting potential energy into hydraulic energy for storage; when the auxiliary device needs to lift or extend, the hydraulic oil stored in the accumulator 6 is precisely regulated by the electromagnetic proportional valve 2, and then supplied to the corresponding chamber of the auxiliary cylinder 8 through the first check valve 1 and the first oil inlet valve 10 to compensate for the energy release and reuse; under the condition that no energy compensation is required, the auxiliary cylinder 8 is directly driven by the oil suction pump 12.

[0083] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the scope of the present invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A hydraulic control system for a bulldozer, characterized in that: The system includes a lifting cylinder (9), which is connected to a second inlet valve (11) and a second check valve (7). The second inlet valve (11) is also connected to the second check valve (7). The second check valve (7) is also connected to an accumulator (6) and a solenoid valve (4). The solenoid valve (4) is connected to the accumulator (6). The solenoid valve (4) is also connected to a solenoid proportional valve (2). The other end of the solenoid proportional valve (2) is connected to a first check valve (1). One end of the first check valve (1) and the second inlet valve (11) are both connected to an oil suction pump (12). The other end of the pump (12) is connected to the oil tank (13), and the second oil inlet valve (11) is also connected to the oil tank (13) to form a return oil channel. The lifting cylinder (9) includes a large lifting chamber (91) and a small lifting chamber (92). Both the large lifting chamber (91) and the small lifting chamber (92) are connected to the second oil inlet valve (11). The second oil inlet valve (11) is also connected to the oil tank (13). The two ends of the electromagnetic proportional valve (2) are connected in parallel with pressure compensation valves (3). One end of the accumulator (6) is also connected to an overflow valve (5). The other end of the overflow valve (5) is connected to the oil tank (13).

2. The hydraulic control system for a bulldozer according to claim 1, characterized in that: The second oil inlet valve (11) is also connected to the first oil inlet valve (10), and the other end of the first oil inlet valve (10) is connected to the auxiliary oil cylinder (8). The first oil inlet valve (10) is also connected to the oil tank (13).

3. A hydraulic control system for a bulldozer according to claim 2, characterized in that: The auxiliary cylinder (8) includes an auxiliary large chamber (81) and an auxiliary small chamber (82), both of which are connected to the first oil inlet valve (10).

4. A hydraulic control method for a bulldozer, characterized in that: The method is applied to the hydraulic control system for a bulldozer according to any one of claims 1-3, and the method includes: Step S1: The bulldozer hydraulic control system collects the bulldozer's control requirements and determines whether it is blade lifting control. If yes, proceed to step S2; otherwise, proceed to step S3. Step S2: The bulldozer enters the blade lifting control mode; Step S3: The bulldozer enters the blade descent control mode; Step S4: Monitor the pressure of the accumulator (6). When the pressure of the accumulator (6) is detected to be higher than the preset value, depressurize.

5. A hydraulic control method for a bulldozer according to claim 4, characterized in that: Step S2 includes: Step S21, the solenoid valve (4) is energized and turned on, opening the oil circuit from the accumulator (6) to the pressure compensation valve (3). The pressure compensation valve (3) automatically adjusts according to the pressure difference between the inlet and outlet of the solenoid proportional valve (2) to ensure that the flow rate is proportional to the valve opening. Step S22: Based on the lifting speed requirement of the bulldozer, monitor the current flow of the accumulator (6), calculate the compensation flow required by the second oil inlet valve (11) through the controller, and generate the corresponding electromagnetic proportional valve (2) control current according to the compensation flow required by the second oil inlet valve (11).

6. A hydraulic control method for a bulldozer according to claim 5, characterized in that: Step S2 also includes: Step S23, the electromagnetic proportional valve (2) opens according to the current opening degree, and the pressure compensation valve (3) monitors the pressure difference between the inlet and outlet of the electromagnetic proportional valve (2) in real time and automatically adjusts the valve core position to ensure that the flow through the electromagnetic proportional valve is only proportional to its opening degree and is not affected by the pressure fluctuation of the accumulator (6) and the change of system load. In step S24, the oil released from the accumulator passes through the electromagnetic proportional valve (2) and the first check valve (1) and then merges with the pressure oil output by the oil suction pump (12) in the pipeline.

7. A hydraulic control method for a bulldozer according to claim 4, characterized in that: Step S3 includes: In step S31, the second oil inlet valve (11) switches to the lowering working position, and the pressure oil output by the oil suction pump (12) enters the lifting large chamber (91) of the lifting cylinder (9), while the lifting small chamber (92) starts to return oil. In step S32, the hydraulic oil discharged from the lifting chamber (92) flows into the accumulator (6) through the working port of the second inlet valve (11) and the second check valve (7), converting the potential energy of the shovel's descent into hydraulic energy and storing it in the accumulator (6).

8. A hydraulic control method for a bulldozer according to claim 4, characterized in that: Step S3 also includes: In step S33, the pressure of the accumulator (6) increases as it is filled with liquid, creating back pressure on the lifting chamber (92), thereby limiting the descent speed and preventing the blade from falling freely; In step S34, when the blade descends to the target position, the second oil inlet valve (11) returns to the neutral position, ending the descent mode. At this time, the accumulator (6) has stored energy, which will be released during the next lifting.

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