Static pressure bulldozer and control method and device thereof

Abstract

The invention relates to the technical field of engineering machinery, and discloses a static pressure bulldozer and a control method and device thereof. The left position of a switching valve in a working hydraulic system of the static pressure bulldozer is communicated with an LS port of a main valve and an X port of a working pump, and the right position of the switching valve is communicated with a P port and an X port of the working pump; an inlet of the proportional pressure reducing valve is connected with a P port of the working pump, and the control output end provides adjusting pressure for a controlled space of the controlled switch valve. And the controlled switch valve is arranged between the P port and the T port of the main valve, and the conduction state of the controlled switch valve is configured to form throttling resistance between the P port and the T port so as to maintain the load pressure required by the system. When it is detected that the rising speed of the rotating speed of the engine exceeds a threshold value, the switching valve is automatically switched to the right position to increase the pump displacement, the proportional pressure reducing valve is adjusted to control the controlled switching valve to form controllable throttling resistance, and overspeed of the engine and out-of-control of an executing mechanism can be effectively restrained under the long downhill and other negative load working conditions.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, specifically to a static pressure bulldozer and its control method and device. Background Technology

[0002] During the operation of construction machinery such as bulldozers, especially under long downhill or heavy-load lowering conditions, the working device generates a significant negative load due to gravity. This negative load drives the hydraulic system in reverse through hydraulic actuators, feeding mechanical energy back into the hydraulic circuit. In hydrostatic transmission or pump-controlled systems, this energy may be further transferred to the engine, causing the engine to be dragged in reverse.

[0003] When the reverse drag power is large and the system lacks an effective energy absorption or damping mechanism, the engine speed will abnormally increase due to external energy input, resulting in overspeed. Engine overspeed not only disrupts its normal combustion and lubrication conditions, but may also cause serious malfunctions such as runaway, component overload, or even mechanical damage, posing a significant threat to equipment safety and the personal safety of operators. Summary of the Invention

[0004] This invention provides a static pressure bulldozer and its control method and device to solve the safety hazards and equipment damage caused by the engine being dragged and overspeeding due to negative load in related technologies.

[0005] In a first aspect, the present invention provides a control method for a static pressure bulldozer, applied to the working hydraulic system of the bulldozer. The working hydraulic system includes a switching valve 3, a one-way throttle valve 2, a proportional pressure reducing valve 5, and a controlled switching valve 6. The left position of the switching valve 3 connects the LS port of the main valve 4 to the X port of the working pump 1, and the right position connects the P port of the working pump 1 to the X port. The inlet of the proportional pressure reducing valve 5 is connected to the P port of the working pump 1, and its control output provides regulating pressure to the controlled space of the controlled switching valve 6. The controlled switching valve 6 is located between the P port and the T port of the main valve 4, and its conduction state is configured to form a throttling resistance between the P port and the T port to maintain the required load pressure of the system. The control method for the pressure bulldozer includes the following steps: When the engine speed rise rate exceeds a preset first threshold, an anti-stalling enable signal is generated based on the engine speed rise rate, and the anti-stalling enable signal is sent to the switching valve 3 to control the switching valve 3 to switch to the right position, so that the pressure at port P of the working pump 1 is introduced into port X of the working pump 1 through the switching valve 3 to adjust the displacement of the working pump 1 to the maximum; Based on the engine speed rise rate, a control current signal for the proportional pressure reducing valve 5 is generated, and the control current signal is sent to the proportional pressure reducing valve 5, so that the output pressure of the proportional pressure reducing valve 5 acts on the controlled switching valve 6, causing the controlled switching valve 6 to switch and conduct the main valve 4 from port P to port T.

[0006] The static pressure bulldozer control method provided by this invention monitors the engine speed increase rate in real time. When it exceeds a preset first threshold, it promptly triggers an overspeed prevention mechanism: on one hand, it controls the switching valve 3 to switch to the right position, introducing the pressure from the P port of the working pump 1 into the X port, forcing the pump displacement to increase to the maximum, and enhancing the system's ability to absorb negative load energy; on the other hand, it dynamically adjusts the output pressure of the proportional pressure reducing valve 5 according to the speed change, driving the controlled switching valve 6 to open the small-opening throttling channel from the P port of the main valve 4 to the T port, forming a controllable return oil resistance. This scheme can effectively suppress actuator runaway and engine overspeed under conditions such as long downhill slopes, and is only activated in abnormal situations, avoiding energy loss due to fixed back pressure, thus balancing safety and efficiency.

[0007] In some optional embodiments, generating the proportional pressure reducing valve 5 control current signal based on the engine speed increase rate includes: acquiring the current engine speed; determining the minimum power required to maintain stable engine operation based on the current engine speed and a preset mapping relationship between engine speed and minimum power; calculating the minimum output pressure of the working pump 1 required to provide the minimum power based on the minimum power, the current engine speed, the maximum displacement of the working pump 1, and the transmission efficiency; determining the target control current value based on the minimum output pressure of the working pump 1 and the preset correspondence between the pump output pressure and the proportional pressure reducing valve 5 control current, and using the target control current value as the proportional pressure reducing valve 5 control current signal.

[0008] This implementation method dynamically calculates the minimum power required to maintain stable operation based on engine speed, and accurately generates the control current of the proportional pressure reducing valve 5 accordingly. This makes the throttling resistance match the actual operating conditions, which can effectively suppress reverse drag and overspeed, and avoid energy waste caused by excessive throttling, thereby improving the system response accuracy, energy efficiency and operational stability.

[0009] In some optional embodiments, the working hydraulic system further includes a main valve 4, a lifting cylinder 8, an electrically controlled pilot valve (12), and a hydraulically controlled back pressure valve 9; the hydraulically controlled back pressure valve 9 is located at the T-port return oil position of the main valve 4, with its inlet connected to the return oil passage of the main valve 4, its outlet connected to the hydraulic oil tank, and a hydraulically controlled port provided; the electrically controlled pilot valve 12 is used to control the lowering action of the lifting cylinder 8, and its output end is port b2; port b2 is connected to the hydraulically controlled port through a control oil circuit, and the method further includes: when a lowering command for the lifting cylinder 8 is received, acquiring the current opening signal of the operating handle; generating a corresponding pilot pressure control command based on the current opening signal; sending the pilot pressure control signal to the electrically controlled pilot valve 12 to control the electrically controlled pilot valve 12 to output a pilot pressure corresponding to the opening of the operating handle to its port b2; so that the pilot pressure of port b2 acts on the hydraulically controlled port through the control oil circuit, driving the hydraulically controlled back pressure valve 9 to reduce the opening of the return oil throttle port and increase the return oil back pressure.

[0010] This implementation adjusts the return oil back pressure in real time by manipulating the handle opening, so that the descent speed of the lifting cylinder 8 matches the operating intention: the larger the handle opening, the higher the back pressure, effectively suppressing the overspeed descent caused by gravity; the smaller the opening, the lower the back pressure, avoiding sluggish action.

[0011] In some alternative implementations, the control method for the static pressure bulldozer further includes the following steps: when receiving an action command other than the descent of the lifting cylinder 8, a b2 unloading control signal is generated and sent to the electronically controlled pilot valve 12 to control the electronically controlled pilot valve 12 to unload its b2 port, so that there is no pressure input to the hydraulic control port, and the hydraulic back pressure valve 9 maintains the minimum return oil back pressure.

[0012] In the non-lifting cylinder 8 descent condition, this implementation automatically controls the unloading of oil port b2, so that the hydraulic back pressure valve 9 returns to the minimum return oil back pressure state, effectively reducing the system return oil resistance, reducing unnecessary energy loss and heat generation, and avoiding interference with other actions such as lifting and tilting, thereby improving the overall machine operation efficiency and response performance.

[0013] In some optional embodiments, the hydraulic back pressure valve 9 integrates a replenishing check valve. The inlet of the replenishing check valve is connected to the hydraulic oil tank, and the outlet is connected to the return oil passage of the large chamber of the lifting cylinder 8. When the pressure of the large chamber of the lifting cylinder 8 is lower than the pressure of the hydraulic oil tank, the replenishing check valve automatically opens under the action of pressure difference, and conducts the replenishing oil passage from the hydraulic oil tank to the large chamber of the lifting cylinder 8.

[0014] This implementation integrates a replenishing check valve into the hydraulic back pressure valve 9. When the lifting cylinder 8 experiences a rapid drop in pressure in the large chamber due to gravity, excessively high return oil throttling back pressure, or insufficient system replenishment, the valve automatically introduces oil from the tank to replenish the oil. This effectively prevents negative pressure or cavitation in the large chamber, thereby avoiding risks such as cavitation, noise, vibration, and damage to seals.

[0015] Secondly, the present invention provides a control device for a static pressure bulldozer, applied to the working hydraulic system of the static pressure bulldozer. The working hydraulic system further includes a switching valve 3, a one-way throttle valve 2, a proportional pressure reducing valve 5, and a controlled switching valve 6. The switching valve 3 is connected in its left position to the LS port of the main valve 4 and the X port of the working pump 1, and in its right position to the P port and the X port of the working pump 1. The inlet of the proportional pressure reducing valve 5 is connected to the P port of the working pump 1, and the outlet outputs control pressure to the control chamber of the controlled switching valve 6. The controlled switching valve 6 is disposed between the P port and the T port of the main valve 4, and its conduction state is configured to form a throttling resistance between the P port and the T port to maintain the required load pressure of the system. The device includes a first control module and a second control module. The first control module is used to generate an anti-stalling enable signal based on the engine speed increase rate when the engine speed increase rate exceeds a preset first threshold, and send the anti-stalling enable signal to the switching valve 3 to control the switching valve 3 to switch to the right position, so that the pressure at the P port of the working pump 1 is introduced into the X port of the working pump 1 through the switching valve 3, thereby adjusting the displacement of the working pump 1 to the maximum. The second control module is used to generate a control current signal for the proportional pressure reducing valve 5 based on the engine speed increase rate, and send the control current signal for the proportional pressure reducing valve 5 to the proportional pressure reducing valve 5 to adjust its output pressure, wherein the output pressure acts on the control chamber of the controlled switching valve 6, driving the controlled switching valve 6 to switch to the left position, and opening the P port of the main valve 4 to the T port.

[0016] Thirdly, the present invention provides an electronic device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the control method of the static pressure bulldozer described in the first aspect or any corresponding embodiment thereof.

[0017] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the control method for a static pressure bulldozer according to the first aspect or any corresponding embodiment thereof.

[0018] Fifthly, the present invention provides a computer program product, including computer instructions for causing a computer to execute the control method for a static pressure bulldozer according to the first aspect or any corresponding embodiment described above. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the working hydraulic system of a static pressure bulldozer according to an embodiment of the present invention; Figure 2 This is a flowchart of a first control method for a static pressure bulldozer according to an embodiment of the present invention; Figure 3 This is a flowchart illustrating an example of a static pressure bulldozer control method according to an embodiment of the present invention; Figure 4 This is a graph showing the output pressure Px and current IA of the proportional pressure reducing valve according to an embodiment of the present invention. Figure 5 This is a graph showing the control pressure Px and inlet pressure P of the controlled switching valve according to an embodiment of the present invention; Figure 6 This is a graph showing the minimum power of the engine and the pump speed according to an embodiment of the present invention; Figure 7 This is a flowchart of a second control method for a static pressure bulldozer according to an embodiment of the present invention; Figure 8 This is a structural block diagram of a static pressure bulldozer control device according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention; The components include: 1. Working pump; 2. One-way throttle valve; 3. Switching valve; 4. Main valve; 5. Proportional pressure reducing valve; 6. Controlled switching valve; 7. Tilting cylinder; 8. Lifting cylinder; 9. Hydraulic back pressure valve; 10. Engine speed sensor; 11. Controller; 12. Electronic pilot valve. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0022] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0023] According to an embodiment of the present invention, a control method for a static pressure bulldozer is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0024] This embodiment provides a control method for a static pressure bulldozer, applied to the working hydraulic system of the static pressure bulldozer, such as... Figure 1 As shown, the working hydraulic system includes a switching valve 3, a one-way throttle valve 2, a proportional pressure reducing valve 5, and a controlled switching valve 6. The left position of the switching valve 3 connects the LS port of the main valve 4 to the X port of the working pump 1, and the right position connects the P port of the working pump 1 to the X port. The inlet of the proportional pressure reducing valve 5 is connected to the P port of the working pump 1, and its outlet outputs control pressure to the control chamber of the controlled switching valve 6. The controlled switching valve 6 is located between the P port and the T port of the main valve 4, and its conduction state is configured to create throttling resistance between the P port and the T port to maintain the required load pressure of the system.

[0025] Specifically, the switching valve 3 can also be called an overspeed protection valve, and the controlled switching valve 6 can be a two-position two-way valve.

[0026] Figure 2 This is a flowchart of a first control method for a static pressure bulldozer according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating an example of a static pressure bulldozer control method according to an embodiment of the present invention, such as... Figure 2 and Figure 3 As shown, the process includes the following steps: Step S201: When the engine speed rise rate exceeds the preset first threshold, an anti-stalling enable signal is generated according to the engine speed rise rate, and the anti-stalling enable signal is sent to the switching valve 3 to control the switching valve 3 to switch to the right position, so that the pressure at the P port of the working pump 1 is introduced into the X port of the working pump 1 through the switching valve 3, so as to adjust the displacement of the working pump 1 to the maximum.

[0027] When a hydrostatic bulldozer is traveling downhill on a long slope or lowering a heavy load, the working device (such as the blade or ripper) generates a negative load due to gravity. This negative load drives the hydraulic system in reverse through hydraulic actuators, feeding mechanical energy back into the hydraulic circuit. In pump-controlled closed or semi-closed hydrostatic systems, this energy may be further transferred to the engine, causing the engine to be "reverse-driven" by the external load. When the reverse-driven power is large and the system lacks an effective energy absorption mechanism, the engine speed will increase rapidly. If the rate of increase in speed exceeds a preset first threshold, it indicates that the system is in a critical state of overspeed risk, which may lead to serious malfunctions such as runaway, lubrication failure, or mechanical damage.

[0028] Switching valve 3 is a solenoid directional valve, which is in the left position by default, connecting the LS port of main valve 4 to the X port of working pump 1, allowing the displacement of working pump 1 to be dynamically adjusted according to system load requirements. When an anti-shutdown enable signal is received, switching valve 3 switches to the right position, cutting off the LS feedback path and directly connecting the P port of working pump 1 to its own X port. Since the pressure at the P port is much higher than the normal LS feedback pressure, the pressure at the X port rises sharply, forcing the swashplate angle of variable working pump 1 to adjust to the maximum displacement position, thereby forcing working pump 1 to output maximum flow. This can significantly improve the power absorption capacity of the hydraulic system, increase engine load, suppress further increase in speed, and prevent overspeed runaway.

[0029] Step S202: Based on the engine speed increase rate, generate a control current signal for the proportional pressure reducing valve 5 and send the control current signal to the proportional pressure reducing valve 5 so that the output pressure of the proportional pressure reducing valve 5 acts on the controlled switching valve 6, causing the controlled switching valve 6 to switch and open the main valve 4P port to the T port.

[0030] While triggering the overspeed prevention function, the controller 11 also calculates and generates a corresponding control current signal for the proportional pressure reducing valve 5 in real time based on the engine speed increase rate, and applies the control current signal to the proportional pressure reducing valve 5. The oil inlet of the proportional pressure reducing valve 5 is connected to the P port of the working pump 1, and its oil outlet outputs a control pressure proportional to the control current. This control pressure is introduced into the control chamber of the controlled switching valve 6. When the control pressure rises to a level sufficient to overcome the reset spring force of the controlled switching valve 6, the valve core switches from the default right position to the left position, allowing the main valve 4 to be connected through a throttling channel with a very small opening between the P port and the T port. Because the throttling opening area is very small, even if only a small amount of oil flows through, it will produce a significant pressure drop, thereby maintaining a high back pressure at the pressure port of the main valve 4. This high-pressure state increases the overall load of the hydraulic system on the one hand, and on the other hand, in conjunction with the working pump 1 operating at maximum displacement, it significantly increases the output power required by the engine, effectively offsetting the energy excess caused by the sudden drop in external load, realizing active suppression of engine speed, and avoiding overspeed faults.

[0031] Specifically, the small-opening throttling channel from the 4P port to the T port of the main valve is configured to generate a throttling pressure drop sufficient to maintain the load pressure required by the system under the hydraulic feedback flow caused by the negative load.

[0032] In one alternative implementation, generating a control current signal for the proportional pressure reducing valve 5 based on the engine speed increase rate includes the following steps Sa1 to Sa4.

[0033] Step Sa1: Obtain the current engine speed.

[0034] Specifically, the current engine speed can be obtained through the engine speed sensor 10.

[0035] Step Sa2: Determine the minimum power required to maintain stable engine operation based on the current engine speed and the preset engine speed-minimum power mapping relationship.

[0036] Specifically, the controller 11 has a pre-stored curve showing the mapping relationship between engine speed and minimum power, such as... Figure 6 As shown, this curve reflects the minimum power required for an engine to avoid overspeeding due to insufficient load at different engine speeds. P e min .

[0037] Step Sa3: Calculate the minimum output pressure of the working pump 1 required to provide the minimum power based on the minimum power, the current engine speed, the maximum displacement of the working pump 1, and the transmission efficiency.

[0038] Specifically, the basic formula based on hydraulic power is: Pe = p Q = p ( n V η ),in, Pe This refers to the engine's output power. p The output pressure of working pump 1, Q = nVη This is the actual output flow rate of working pump 1. V This is the maximum displacement of working pump 1. η This refers to the overall transmission efficiency from the engine to the hydraulic system.

[0039] Under overspeed protection, the displacement of the working pump 1 is fixed at its maximum value. V Therefore, in order to achieve at least P e min Power absorption, required minimum output pressure of working pump 1 p min can be accessed Calculated.

[0040] Step Sa4: Based on the minimum output pressure of the working pump 1 and the preset mapping relationship between the output pressure of the working pump 1 and the control current of the proportional pressure reducing valve 5, determine the target control current value and use the target control current value as the control current signal of the proportional pressure reducing valve 5.

[0041] Specifically, the controller 11 has a pre-stored mapping relationship between the output pressure of the working pump 1 and the control current of the proportional pressure reducing valve 5, such as... Figure 4As shown, this mapping relationship reflects the amount of control current required by the proportional pressure reducing valve 5 to maintain a specific output pressure of the hydraulic system at a given working pump 1. This relationship comprehensively considers the throttling characteristics of the controlled switching valve 6 and the matching relationship between the pressure required in its control chamber and the output pressure of the proportional pressure reducing valve 5, as follows: Figure 5 As shown.

[0042] After determining the target control current value, the controller 11 outputs it as the control current signal of the proportional pressure reducing valve 5, driving the proportional pressure reducing valve 5 to adjust its outlet pressure, thereby establishing the required system back pressure through the controlled switching valve 6, ensuring that the engine absorbs sufficient load power and effectively preventing overspeed.

[0043] The static pressure bulldozer control method provided by this invention monitors the engine speed increase rate in real time. When it exceeds a preset first threshold, it promptly triggers an overspeed prevention mechanism: on one hand, it controls the switching valve 3 to switch to the right position, introducing the pressure from the P port of the working pump 1 into the X port, forcing the pump displacement to increase to the maximum, and enhancing the system's ability to absorb negative load energy; on the other hand, it dynamically adjusts the output pressure of the proportional pressure reducing valve 5 according to the speed change, driving the controlled switching valve 6 to open the small-opening throttling channel from the P port of the main valve 4 to the T port, forming a controllable return oil resistance. This scheme can effectively suppress actuator runaway and engine overspeed under conditions such as long downhill slopes, and is only activated in abnormal situations, avoiding energy loss due to fixed back pressure, thus balancing safety and efficiency.

[0044] When the bulldozer's lifting cylinder descends, the negative load generated by gravity causes it to descend at high speed. To avoid this, a fixed back pressure valve is usually added to the hydraulic return line, or a multi-way valve is used to provide a stable back pressure. However, the back pressure from the back pressure valve or multi-way valve is only needed for specific actions, and adding it to the return line would cause unnecessary energy loss. Furthermore, this back pressure is not adjustable; it cannot be adjusted by the handle opening or the descent speed. This can lead to high return resistance at slow descent speeds and ineffective prevention of high-speed descent at fast descent speeds.

[0045] Based on this, this embodiment also provides a control method for a static pressure bulldozer, applied to the working hydraulic system of the static pressure bulldozer. The working hydraulic system also includes a main valve 4, a lifting cylinder 8, an electrically controlled pilot valve 12, and a hydraulically controlled back pressure valve 9. The hydraulically controlled back pressure valve 9 is located at the T-port return oil position of the main valve 4, with its inlet connected to the return oil passage of the main valve 4 and its outlet connected to the hydraulic oil tank, and is equipped with a hydraulic control port. The electrically controlled pilot valve 12 is used to control the lowering action of the lifting cylinder 8, and its output end is port b2. Port b2 is connected to the hydraulic control port through a control oil circuit. For example, the static pressure bulldozer also includes a tilting cylinder 7.

[0046] Among them, the hydraulic back pressure valve 9 can also be called the adjustable oil replenishment back pressure valve.

[0047] Figure 7 This is a flowchart of a second control method for a static pressure bulldozer according to an embodiment of the present invention, as shown below. Figure 7 As shown, the process includes the following steps: Step S701: When the engine speed rise rate exceeds the preset second threshold, an anti-stalling enable signal is generated according to the engine speed rise rate, and the anti-stalling enable signal is sent to the switching valve 3 to control the switching valve 3 to switch to the right position, so that the pressure at the P port of the working pump 1 is introduced into the X port of the working pump 1 through the switching valve 3, so as to adjust the displacement of the working pump 1 to the maximum.

[0048] Step S702: Based on the engine speed increase rate, generate a control current signal for the proportional pressure reducing valve 5 and send the control current signal to the proportional pressure reducing valve 5 so that the output pressure of the proportional pressure reducing valve 5 acts on the controlled switching valve 6, causing the controlled switching valve 6 to switch and open the main valve 4P port to the T port.

[0049] Step S703: When a command to lower the lifting cylinder 8 is received, the current opening signal of the control handle is obtained.

[0050] In the working hydraulic system of the hydrostatic bulldozer, the operator controls the movement of the lifting cylinder 8 by operating a handle. When the handle is operated to the lowering region, the system recognizes this action as a lowering command for the lifting cylinder 8. At this time, the controller 11 collects the opening signal corresponding to the mechanical position of the operating handle or the output of the potentiometer in real time. This signal accurately reflects the lowering speed desired by the operator; the larger the handle opening, the faster the desired descent.

[0051] Step S704: Generate the corresponding pilot pressure control command based on the current opening signal.

[0052] Specifically, based on the acquired control handle opening signal and a preset mapping relationship, the corresponding pilot pressure control command can be calculated and generated.

[0053] Step S705: Send the pilot pressure control signal to the electronically controlled pilot valve 12 to control the electronically controlled pilot valve 12 to output pilot pressure corresponding to the opening degree of the operating handle to its b2 port; so that the pilot pressure of the b2 port acts on the hydraulic control port through the control oil circuit, driving the hydraulic control back pressure valve 9 to reduce the opening degree of the return oil throttle port and increase the return oil back pressure.

[0054] Specifically, the controller 11 sends the generated pilot pressure control signal to the electronically controlled pilot valve 12, driving its internal electromagnetic components to operate, thereby adjusting the output pressure of port b2. Since port b2 is directly connected to the hydraulic control port pst of the hydraulic back pressure valve 9 through the control oil circuit, the pilot pressure is then applied to the control chamber of the back pressure valve.

[0055] Under the pressure of the hydraulic control port PST, the main valve 4 core of the hydraulic control back pressure valve 9 moves upward against the force of the reset spring, reducing the flow area of ​​the return oil throttling port, which leads to an increase in the return oil resistance of the main valve 4T port, that is, an increase in the return oil back pressure.

[0056] The greater the handle opening, the higher the pilot pressure output from port b2 of the electronically controlled pilot valve 12. This, in turn, increases the pressure transmitted to the hydraulically controlled port pst via the control oil circuit, thereby causing the return oil back pressure provided by the back pressure valve to rise synchronously. This mechanism effectively suppresses the accelerated descent trend of the lifting cylinder 8 under gravity. Since a faster descent speed requires a greater return oil back pressure, and the actual back pressure provided by the system automatically matches the operating intention, this ensures that the lifting cylinder 8 is stable and controllable throughout the entire descent stroke, and prevents cavitation in the large chamber due to insufficient instantaneous flow.

[0057] Furthermore, when receiving action commands other than the descent of the lifting cylinder 8, a b2 unloading control signal is generated and sent to the electronic pilot valve 12 to control the electronic pilot valve 12 to unload its b2 port, so that there is no pressure input to the hydraulic control port, and the hydraulic back pressure valve 9 maintains the minimum return oil back pressure.

[0058] In other words, when receiving action commands other than the descent of the lifting cylinder 8 (such as tilting, lifting, neutral position holding, etc.), the controller 11 generates a b2 unloading control signal and sends this signal to the electronically controlled pilot valve 12, controlling it to connect the b2 port to the return oil (T port), thus achieving active unloading. At this time, the pressure at the b2 port is released to the system low pressure (close to the oil tank pressure), and there is no effective control pressure input at the hydraulic control port pst. The hydraulic back pressure valve 9 returns to its initial position under the action of the return spring, maintaining the minimum return oil throttling opening, thereby maintaining the minimum return oil back pressure. This design ensures that the system return oil resistance is minimized under non-descent conditions, avoiding unnecessary energy loss and heat generation, while not affecting the action response performance of other actuators.

[0059] Furthermore, the hydraulic back pressure valve 9 also integrates a replenishing check valve. The inlet of the replenishing check valve is connected to the hydraulic oil tank, and the outlet is connected to the return oil passage of the large chamber of the lifting cylinder 8. When the pressure in the large chamber of the lifting cylinder 8 is lower than the pressure in the hydraulic oil tank, the built-in replenishing check valve in the hydraulic back pressure valve 9 automatically opens under the action of the pressure difference, opening the replenishing oil passage from the hydraulic oil tank to the large chamber of the lifting cylinder 8.

[0060] This is because when the lifting cylinder 8 descends rapidly under gravity, if the back pressure generated by the oil supply flow or return throttling of the main valve 4 causes the instantaneous volume change rate of the large cavity to exceed the system's oil replenishment capacity, the pressure in the large cavity may rapidly drop below the hydraulic oil tank pressure, creating a negative pressure state. At this time, a positive pressure difference is generated between the oil tank and the large cavity, pointing from the oil tank to the large cavity. Under the action of this pressure difference, the oil replenishment check valve automatically opens, opening the oil replenishment passage from the hydraulic oil tank to the large cavity of the lifting cylinder 8, replenishing the oil in time, and preventing cavitation, noise, vibration, or seal damage caused by cavitation. This oil replenishment process is entirely driven by the pressure difference, without the need for intervention from the controller 11, and features fast response and high reliability, thus providing passive safety protection for the system while achieving adaptive back pressure adjustment.

[0061] The static pressure bulldozer control method provided in this embodiment adjusts the return oil back pressure in real time by manipulating the handle opening, so that the descent speed of the lifting cylinder 8 matches the operating intention: the larger the handle opening, the higher the back pressure, effectively suppressing the overspeed descent caused by gravity; the smaller the opening, the lower the back pressure, avoiding sluggish action.

[0062] This embodiment also provides a control device for a static pressure bulldozer, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0063] This embodiment provides a control device for a static pressure bulldozer, applied to the working hydraulic system of the bulldozer. The working hydraulic system further includes a switching valve 3, a one-way throttle valve 2, a proportional pressure reducing valve 5, and a controlled switching valve 6. The switching valve 3 is connected in its left position to the LS port of the main valve 4 and the X port of the working pump 1, and in its right position to the P port of the working pump 1 and the X port. The inlet of the proportional pressure reducing valve 5 is connected to the P port of the working pump 1, and its outlet outputs control pressure to the control chamber of the controlled switching valve 6. The controlled switching valve 6 is located between the P port and the T port of the main valve 4, and its conduction state is configured to form a throttling resistance between the P port and the T port to maintain the required load pressure of the system. Figure 8 As shown, the control device of the static pressure bulldozer includes a first control module and a second control module.

[0064] The first control module 801 is used to generate an anti-stalling enable signal based on the engine speed increase rate when the engine speed rise rate exceeds a preset first threshold, and send the anti-stalling enable signal to the switching valve 3 to control the switching valve 3 to switch to the right position, so that the pressure of the working pump 1P port is introduced into the working pump 1X port through the switching valve 3, thereby adjusting the displacement of the working pump 1 to the maximum.

[0065] The second control module 802 is used to generate a control current signal for the proportional pressure reducing valve 5 according to the engine speed increase rate, and send the control current signal for the proportional pressure reducing valve 5 to the proportional pressure reducing valve 5 to adjust its output pressure. The output pressure acts on the control chamber of the controlled switching valve 6, driving the controlled switching valve 6 to switch to the left position and opening the small opening throttling channel from the P port to the T port of the main valve 4.

[0066] In some optional implementations, the second control module 802 is specifically used for: acquiring the current engine speed; determining the minimum power required to maintain stable engine operation based on the current engine speed and a preset mapping relationship between engine speed and minimum power; calculating the minimum output pressure of the working pump 1 required to provide the minimum power based on the minimum power, the current engine speed, the maximum displacement of the working pump 1, and the transmission efficiency; determining a target control current value based on the minimum output pressure of the working pump 1 and a preset correspondence between the pump output pressure and the control current of the proportional pressure reducing valve 5, and using the target control current value as the control current signal of the proportional pressure reducing valve 5.

[0067] In some optional embodiments, the working hydraulic system further includes a main valve 4, a lifting cylinder 8, an electrically controlled pilot valve 12, and a hydraulically controlled back pressure valve 9; the hydraulically controlled back pressure valve 9 is located at the T-port return oil position of the main valve 4, with its inlet connected to the return oil passage of the main valve 4, its outlet connected to the hydraulic oil tank, and it has a hydraulically controlled port; the electrically controlled pilot valve 12 is used to control the lowering action of the lifting cylinder 8, and its output end is port b2; port b2 is connected to the hydraulically controlled port through a control oil circuit. The control device of the static pressure bulldozer also includes a third control module. The third control module is used to acquire the current opening signal of the control handle when it receives the lowering command of the lifting cylinder 8; generate a corresponding pilot pressure control command based on the current opening signal; send the pilot pressure control signal to the electronically controlled pilot valve 12 to control the electronically controlled pilot valve 12 to output a pilot pressure corresponding to the opening of the control handle to its b2 port; so that the pilot pressure of the b2 port acts on the hydraulic control port through the control oil circuit, driving the hydraulic back pressure valve 9 to reduce the opening of the return oil throttle port and increase the return oil back pressure.

[0068] In some optional implementations, the third control module is specifically used to: when receiving an action command other than the descent of the lifting cylinder 8, generate a b2 unloading control signal and send the b2 unloading control signal to the electronically controlled pilot valve 12 to control the electronically controlled pilot valve 12 to unload its b2 port, so that there is no pressure input to the hydraulic control port, and the hydraulically controlled back pressure valve 9 maintains the minimum return oil back pressure.

[0069] In some optional embodiments, the hydraulic back pressure valve 9 integrates a replenishing check valve. The inlet of the replenishing check valve is connected to the hydraulic oil tank, and the outlet is connected to the return oil passage of the large chamber of the lifting cylinder 8. When the pressure of the large chamber of the lifting cylinder 8 is lower than the pressure of the hydraulic oil tank, the replenishing check valve automatically opens under the action of pressure difference, and conducts the replenishing oil passage from the hydraulic oil tank to the large chamber of the lifting cylinder 8.

[0070] The control device for a hydrostatic bulldozer provided in this embodiment of the invention can execute the control method for a hydrostatic bulldozer provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the various modules and units described above are the same as in the corresponding embodiments described above, and will not be repeated here.

[0071] This invention also provides an electronic device. Figure 9 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. Furthermore, an embodiment of the present invention also provides a static pressure bulldozer, including the aforementioned electronic device.

[0072] The following is a detailed reference. Figure 9 This diagram illustrates a structural schematic suitable for implementing an electronic device according to embodiments of the present invention. The electronic device may include a processor (e.g., a central processing unit, graphics processor, etc.) 901, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 902 or a program loaded from memory 908 into random access memory (RAM) 903. The RAM 903 also stores various programs and data required for the operation of the electronic device. The processor 901, ROM 902, and RAM 903 are interconnected via a bus 904. An input / output (I / O) interface 905 is also connected to the bus 904.

[0073] Typically, the following devices can be connected to I / O interface 905: input devices 906 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 907 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 908 including, for example, magnetic tapes, hard disks, etc.; and communication devices 909. Communication device 909 allows electronic devices to exchange data via wireless or wired communication with other devices. Although Figure 9Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown, and more or fewer devices may be implemented or have instead.

[0074] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 909, or installed from a memory 908, or installed from a ROM 902. When the computer program is executed by the processor 901, it performs the functions defined in the control method for a static pressure bulldozer according to embodiments of the present invention.

[0075] Figure 9 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0076] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that the computer, processor, microprocessor controller 11, or programmable hardware includes storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the control method for the static pressure bulldozer shown in the above embodiments is implemented.

[0077] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0078] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A control method for a static pressure bulldozer, applied to the working hydraulic system of the static pressure bulldozer, the working hydraulic system comprising a switching valve (3), a one-way throttle valve (2), a proportional pressure reducing valve (5), and a controlled switching valve (6); the left position of the switching valve (3) is connected to the LS port of the main valve (4) and the X port of the working pump (1), and the right position is connected to the P port and the X port of the working pump (1); the inlet of the proportional pressure reducing valve (5) is connected to the P port of the working pump (1), and the control output provides regulating pressure to the controlled space of the controlled switching valve (6); the controlled switching valve (6) is disposed between the P port and the T port of the main valve (4), and its conduction state is configured to form a throttling resistance between the P port and the T port to maintain the load pressure required by the system, characterized in that, The method includes: When the engine speed rise rate exceeds the preset first threshold, an anti-shutdown enable signal is generated according to the engine speed rise rate, and the anti-shutdown enable signal is sent to the switching valve (3) to control the switching valve (3) to switch to the right position, so that the pressure of the P port of the working pump (1) is introduced into the X port of the working pump (1) through the switching valve (3) to adjust the displacement of the working pump (1) to the maximum. Based on the engine speed increase rate, a control current signal for the proportional pressure reducing valve (5) is generated and sent to the proportional pressure reducing valve (5) so that the output pressure of the proportional pressure reducing valve (5) acts on the controlled switching valve (6), causing the controlled switching valve (6) to switch and open the main valve (4) from port P to port T.

2. The method according to claim 1, characterized in that, The process of generating a control current signal for the proportional pressure reducing valve (5) based on the engine speed increase rate includes: Get the current engine speed; Based on the current engine speed and the preset engine speed-minimum power mapping relationship, determine the minimum power required to maintain stable engine operation; Based on the minimum power, current engine speed, maximum displacement of working pump (1), and transmission efficiency, calculate the minimum output pressure of working pump (1) required to provide the minimum power; Based on the correspondence between the minimum output pressure of the working pump (1) and the preset pump output pressure and the control current of the proportional pressure reducing valve (5), the target control current value is determined, and the target control current value is used as the control current signal of the proportional pressure reducing valve (5).

3. The method according to claim 1, characterized in that, The working hydraulic system also includes a main valve (4), a lifting cylinder (8), an electrically controlled pilot valve (12), and a hydraulically controlled back pressure valve (9); the hydraulically controlled back pressure valve (9) is located at the T-port return oil position of the main valve (4), with its inlet connected to the return oil passage of the main valve (4), its outlet connected to the hydraulic oil tank, and it is equipped with a hydraulic control port; the electrically controlled pilot valve (12) is used to control the lowering action of the lifting cylinder (8), and its output end is port b2; The b2 port is connected to the hydraulic control port via a control oil circuit, and the method further includes: When the lowering command of the lifting cylinder (8) is received, the current opening signal of the control handle is obtained; Generate a corresponding pilot pressure control command based on the current opening signal; The pilot pressure control signal is sent to the electronically controlled pilot valve (12) to control the electronically controlled pilot valve (12) to output a pilot pressure corresponding to the opening degree of the operating handle to its b2 port; so that the pilot pressure of the b2 port acts on the hydraulic control port through the control oil circuit, driving the hydraulic control back pressure valve (9) to reduce the opening degree of the return oil throttle port and increase the return oil back pressure.

4. The method according to claim 3, characterized in that, Also includes: When receiving an action command other than the descent of the lifting cylinder (8), a b2 unloading control signal is generated and sent to the electronic pilot valve (12) to control the electronic pilot valve (12) to unload its b2 port, so that there is no pressure input to the hydraulic control port, and the hydraulic back pressure valve (9) maintains the minimum return oil back pressure.

5. The method according to claim 3, characterized in that, The hydraulic back pressure valve (9) integrates a replenishing check valve. The inlet of the replenishing check valve is connected to the hydraulic oil tank, and the outlet is connected to the return oil passage of the large cavity of the lifting cylinder (8). When the pressure of the large cavity of the lifting cylinder (8) is lower than the pressure of the hydraulic oil tank, the replenishing check valve automatically opens under the action of pressure difference, and conducts the replenishing oil passage from the hydraulic oil tank to the large cavity of the lifting cylinder (8).

6. A control device for a static pressure bulldozer, applied to the working hydraulic system of the static pressure bulldozer, the working hydraulic system further comprising a switching valve (3), a one-way throttle valve (2), a proportional pressure reducing valve (5), and a controlled switching valve (6); the switching valve (3) is connected in its left position to the LS port of the main valve (4) and the X port of the working pump (1), and in its right position to the P port and the X port of the working pump (1); the inlet of the proportional pressure reducing valve (5) is connected to the P port of the working pump (1), and the outlet outputs control pressure to the control chamber of the controlled switching valve (6); the controlled switching valve (6) is disposed between the P port and the T port of the main valve (4), and its conduction state is configured to form a throttling resistance between the P port and the T port to maintain the load pressure required by the system, characterized in that, The device includes: The first control module is used to generate an anti-shutdown enable signal according to the engine speed increase rate when the engine speed rise rate exceeds the preset first threshold, and send the anti-shutdown enable signal to the switching valve (3) to control the switching valve (3) to switch to the right position, so that the pressure of the P port of the working pump (1) is introduced into the X port of the working pump (1) through the switching valve (3), thereby adjusting the displacement of the working pump (1) to the maximum. The second control module is used to generate a control current signal for the proportional pressure reducing valve (5) according to the engine speed increase rate, and send the control current signal for the proportional pressure reducing valve (5) to the proportional pressure reducing valve (5) to adjust its output pressure, wherein the output pressure acts on the control chamber of the controlled switch valve (6) to drive the controlled switch valve (6) to switch to the left position and connect the P port of the main valve (4) to the T port.

7. An electronic device, characterized in that, include: A memory and a processor are communicatively connected, the memory stores computer instructions, and the processor executes the computer instructions to perform the control method of the static pressure bulldozer according to any one of claims 1 to 5.

8. A static pressure bulldozer, characterized in that, Includes the electronic device as described in claim 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the control method for the static pressure bulldozer according to any one of claims 1 to 5.

10. A computer program product, characterized in that, Includes computer instructions for causing a computer to perform the control method for a static pressure bulldozer as described in any one of claims 1 to 5.

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