Hydraulic control system for a dozer blade and a track excavator
Patent Information
- Application Number
- CN202611508425.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-24
- Publication Date
- 2026-11-03
AI Technical Summary
When adding a bulldozer blade and its hydraulic control system to existing medium-sized tracked excavators, the modification work is extensive and costly. Furthermore, the newly added oil pipes are prone to twisting, interference, and wear, which affects long-term reliability.
The main actuator circuit of the bulldozer blade is formed by using the backup valve connection of the main valve, which reduces the need to modify the high-pressure pipeline of the main pump and the original valve group. The bulldozer blade foot valve provides independent foot pilot operation, and the pilot pressure signal is combined with the bulldozer blade shuttle valve. The sensor feeds back to the vehicle controller to determine the working status.
It enables convenient modification of bulldozer blades, reduces the amount of modification and cost, improves the reliability of the hydraulic system and the coordination of overall vehicle control, and avoids hose twisting and wear.
Smart Images
Figure CN123027882A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of construction machinery, and in particular to a hydraulic control system for a bulldozer blade. Furthermore, this invention also relates to a tracked excavator including the aforementioned hydraulic control system for a bulldozer blade. Background Technology
[0002] In site leveling, backfilling, obstacle clearing, and overall machine support operations, the bulldozer blade on a tracked excavator can perform functions such as pushing materials, leveling, and providing auxiliary support. Most existing medium-sized tracked excavators, especially those in the 13-18 ton class, do not come equipped with a bulldozer blade at the factory. Therefore, after the equipment enters a specific construction scenario, the demand arises for adding a bulldozer blade and its hydraulic control system, depending on the user's working conditions. For such aftermarket additions, in addition to achieving basic blade raising and lowering movements, it is also necessary to ensure the integrity of the original hydraulic system, the upper structure's slewing motion, the bulldozer blade's static locking, and the vehicle controller's recognition of the new movements.
[0003] Existing retrofit solutions typically involve adding an independent directional valve in addition to the main valve, and accordingly modifying the main pump high-pressure pipeline, return oil pipeline, and pilot line. This method requires an increase in the number of valves, connectors, and hoses, resulting in a high workload and cost, and altering the original hydraulic system's piping connections. Furthermore, the upper structure of a tracked excavator can rotate 360° relative to the lower structure. If a conventional aftermarket retrofit solution involves directly traversing the rotation area with new hydraulic lines, hose entanglement, interference, and wear are likely to occur, leading to poor long-term reliability.
[0004] Therefore, how to provide a hydraulic control system for bulldozer blades that is easy to modify is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention
[0005] The purpose of this invention is to provide a bulldozer blade hydraulic control system that utilizes the backup valve connection of the main valve to form the main execution circuit of the bulldozer blade, thereby reducing modifications to the main pump high-pressure pipeline and the original vehicle valve assembly. Another purpose of this invention is to provide a tracked excavator including the above-mentioned bulldozer blade hydraulic control system.
[0006] To solve the above-mentioned technical problems, the present invention provides a bulldozer blade hydraulic control system, including a main valve, a backup valve assembly, a bulldozer blade cylinder, and a bulldozer blade foot valve. The backup valve assembly includes a bulldozer blade directional valve. The main valve is connected to the inlet and outlet of the bulldozer blade directional valve. The lifting port of the bulldozer blade directional valve is connected to the rodless chamber of the bulldozer blade cylinder. The lowering port of the bulldozer blade directional valve is connected to the rod chamber of the bulldozer blade cylinder. The lifting output port of the bulldozer blade foot valve is connected to the lifting hydraulic control port of the bulldozer blade directional valve. The lowering output port of the bulldozer blade foot valve is connected to the lowering hydraulic control port of the bulldozer blade directional valve. The lifting and lowering output ports of the bulldozer blade foot valve are respectively connected to the two inlets of the bulldozer blade shuttle valve. The outlet of the bulldozer blade shuttle valve is connected to a sensor. The vehicle controller determines the working status of the bulldozer blade based on the detection results of the sensor.
[0007] Preferably, the backup valve assembly further includes a hydraulically controlled check valve and two overload relief valves. The inlet of the bulldozer blade reversing valve is connected to the output oil circuit of the main valve, the return oil port of the bulldozer blade reversing valve is connected to the return oil circuit of the main valve, the hydraulically controlled check valve is installed at the inlet of the bulldozer blade reversing valve, the lifting oil port and lowering oil port of the bulldozer blade reversing valve are respectively connected to the inlets of the two overload relief valves, the outlet of the overload relief valve is connected to the return oil circuit, and the overload relief valve is provided with an oil replenishment structure.
[0008] Preferably, the bulldozer blade reversing valve is a three-position four-way hydraulic reversing valve.
[0009] Preferably, the device includes a main shuttle valve, the outlet of which is connected to an inlet of the main shuttle valve, and the outlet of which is connected to the sensor.
[0010] Preferably, the system includes a support frame, with the main valve and the backup valve connected at the rear end of the support frame, the bulldozer blade foot valve installed at the front end of the support frame, a rotary joint provided in the middle of the support frame, the backup valve connected to the bulldozer blade foot valve through the rotary joint, and the sensor installed at the rear end of the support frame.
[0011] Preferably, the device includes two bulldozer blade cylinders arranged in parallel, and the bulldozer blade reversing valve is connected to the bulldozer blade cylinders via a hydraulic lock.
[0012] Preferably, the return port of the travel pilot valve is connected to the return oil circuit, and the return oil circuit is equipped with a bypass shut-off valve. When the foot pedal is pressed, a switching signal is sent to the bypass shut-off valve to cut off the return oil circuit.
[0013] Preferably, the bypass shut-off valve is a two-position, two-way hydraulically controlled directional valve, and the lifting and lowering output ports of the bulldozer blade foot valve are connected to the hydraulically controlled ports of the bypass shut-off valve.
[0014] Preferably, a one-way throttle valve is provided at the hydraulic control port of the bypass shut-off valve, and a forward-directing tubular one-way valve is provided at the hydraulic control port of the main valve.
[0015] The present invention provides a tracked excavator, including a bulldozer blade hydraulic control system as described in any of the above claims.
[0016] This invention provides a bulldozer blade hydraulic control system, including a main valve, a backup valve assembly, a bulldozer blade cylinder, and a bulldozer blade foot valve. The backup valve assembly includes a bulldozer blade directional valve. The main valve is connected to the inlet and outlet of the bulldozer blade directional valve. The lifting port of the bulldozer blade directional valve is connected to the rodless chamber of the bulldozer blade cylinder, and the lowering port of the bulldozer blade directional valve is connected to the rod chamber of the bulldozer blade cylinder. The lifting output port of the bulldozer blade foot valve is connected to the lifting hydraulic control port of the bulldozer blade directional valve, and the lowering output port of the bulldozer blade foot valve is connected to the lowering hydraulic control port of the bulldozer blade directional valve. The lifting and lowering output ports of the bulldozer blade foot valve are respectively connected to the two inlets of the bulldozer blade shuttle valve. The outlet of the bulldozer blade shuttle valve is connected to a sensor. The vehicle controller determines the working status of the bulldozer blade based on the sensor detection results.
[0017] By utilizing the existing spare valve connection of the main valve to form the main execution circuit of the bulldozer blade, compared with the modification method of adding an external independent main directional valve, it is possible to reduce the modification of the main pump high-pressure pipeline and the original vehicle valve group. The bulldozer blade foot valve provides independent foot-operated pilot operation, allowing the operator to raise or lower the blade by foot, which facilitates the coordination of working conditions between walking, digging and bulldozer blade actions. The bulldozer blade shuttle valve combines the pilot pressure of raising and lowering the blade into a single detection signal, which is then fed back to the vehicle controller by a sensor. A single pressure sensor can be used to identify whether the bulldozer blade is in an operating state. The hydraulic execution circuit itself does not require this electrical detection signal as a necessary condition for the action to be established. Therefore, the sensor mainly undertakes the functions of status feedback and control strategy input, which is beneficial to balance detection function and hydraulic operation reliability.
[0018] The present invention also provides a tracked excavator including the above-mentioned bulldozer blade hydraulic control system. Since the above-mentioned bulldozer blade hydraulic control system has the above-mentioned technical effects, the above-mentioned tracked excavator should also have the same technical effects, which will not be described in detail here. Attached Figure Description
[0019] Figure 1 A hydraulic schematic diagram of a specific embodiment of the bulldozer blade hydraulic control system provided by the present invention; Figure 2 This is a schematic diagram of a specific embodiment of the bulldozer blade hydraulic control system provided by the present invention.
[0020] Among them, 1-main valve; 2-bulldozer blade directional valve; 3-bulldozer blade cylinder; 4-bulldozer blade foot valve; 5-bulldozer blade shuttle valve; 6-sensor; 7-hydraulic control check valve; 8-overload relief valve; 9-main shuttle valve; 10-support; 11-rotary joint; 12-hydraulic lock; 13-bypass shut-off valve; 14-one-way throttle valve; 15-pipe-type check valve. Detailed Implementation
[0021] The core of this invention is to provide a bulldozer blade hydraulic control system that utilizes the backup valve connection of the main valve to form the main execution circuit of the bulldozer blade, thereby reducing modifications to the main pump high-pressure pipeline and the original vehicle valve assembly. Another core aspect of this invention is to provide a tracked excavator that includes the aforementioned bulldozer blade hydraulic control system.
[0022] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0023] Please refer to Figure 1 and Figure 2 , Figure 1 A hydraulic schematic diagram of a specific embodiment of the bulldozer blade hydraulic control system provided by the present invention; Figure 2 This is a schematic diagram of a specific embodiment of the bulldozer blade hydraulic control system provided by the present invention.
[0024] This invention provides a hydraulic control system for a bulldozer blade, including a main valve 1, a backup valve assembly, a bulldozer blade cylinder 3, and a bulldozer blade foot valve 4. The backup valve assembly includes a bulldozer blade directional valve 2. The main valve 1 supplies main pressure oil to the backup valve assembly and forms a return oil channel. The bulldozer blade directional valve 2 is controlled by pilot pressure and switches between different working positions, selectively supplying oil to either the lifting or lowering execution branch. The bulldozer blade foot valve 4 is located in a position where the operator can control it with their foot. Its input end receives pilot pressure oil, generating lifting and lowering pilot signals respectively when the foot pedal is depressed. Thus, the main oil circuit provides the flow and pressure required to drive the bulldozer blade cylinder 3, while the pilot oil circuit controls the switching of the bulldozer blade directional valve 2; the two functions cooperate with each other.
[0025] During the lifting operation, the operator depresses the lifting foot pedal of the bulldozer foot valve 4. This establishes pilot pressure at the lifting output port of the bulldozer foot valve 4. This pilot pressure is transmitted to the lifting hydraulic control port of the bulldozer directional valve 2, causing the bulldozer directional valve 2 to switch from the neutral position to the lifting working position. The lifting working port of the bulldozer directional valve 2 receives pressurized oil from the main valve 1 and establishes pressure in the corresponding actuator oil circuit on the rodless side. The oil on the other side returns to the main valve's return oil circuit through the corresponding return oil channel, thereby driving the bulldozer cylinder 3 to extend and move the bulldozer blade in the lifting direction. Furthermore, as the amount of foot pedal movement changes, the pilot pressure changes accordingly, allowing the valve core opening degree and operating speed to be adjusted according to the operation.
[0026] During the lowering operation, the operator depresses the lowering foot pedal of the bulldozer blade foot valve 4. The lowering output port establishes pilot pressure, which acts on the lowering hydraulic control port of the bulldozer blade reversing valve 2, switching the bulldozer blade reversing valve 2 to the lowering position. At this time, the pressurized oil supplied by the main valve 1 enters the actuator oil circuit corresponding to the rod-side via the bulldozer blade reversing valve 2, while the return oil from the other side returns to the return oil circuit via the reversing valve. The bulldozer blade cylinder 3 then drives the bulldozer blade downwards. By setting the lifting and lowering controls to two separate pilot output directions, a clear correspondence can be established between the direction of the bulldozer blade lifting and lowering operations and the foot pedal, avoiding the use of the main handle which occupies the original digging action control channel.
[0027] The lifting and lowering output ports of the bulldozer blade foot valve 4 are also connected to the two inlets of the bulldozer blade shuttle valve 5. The bulldozer blade shuttle valve 5 operates according to high-pressure selection logic. When pilot pressure is established in either the lifting or lowering output port, the bulldozer blade shuttle valve 5 will generate corresponding pressure at its outlet, while the other output will not reverse through to the currently unoperated pilot branch. The outlet of the bulldozer blade shuttle valve 5 is connected to sensor 6, thus eliminating the need for two separate pressure sensors for lifting and lowering the blade; both types of foot pedal operation can be uniformly converted into a pressure status signal indicating that the bulldozer blade is in operation.
[0028] Sensor 6 detects the pressure at the output of the bulldozer blade shuttle valve 5 and provides the detection result to the vehicle controller. When the foot pedal is fully released, both pilot outputs of the bulldozer blade foot valve 4 are depressurized, and the outlet pressure of the bulldozer blade shuttle valve 5 drops. Based on this, the vehicle controller determines that the bulldozer blade is in an inactive state. When the operator presses either foot pedal, sensor 6 detects the pilot pressure, and the vehicle controller determines that the bulldozer blade is in an active state. This detection path exists in parallel with the hydraulic pilot control path of the bulldozer blade reversing valve 2, meaning that the pressure signal both actually drives the hydraulic valve core to complete the action and can be converted into status information that the vehicle controller can recognize.
[0029] The main actuator circuit for the bulldozer blade is formed by utilizing the existing spare valve connection of the main valve 1. Compared with the modification method of adding an external independent main directional valve, this reduces the need for modifications to the main pump high-pressure pipeline and the original vehicle valve group. The bulldozer blade foot valve 4 provides independent foot-operated pilot operation, allowing the operator to raise or lower the blade by foot, facilitating the coordination of working conditions between walking, digging, and bulldozer blade actions. The bulldozer blade shuttle valve 5 combines the pilot pressures for raising and lowering the blade into a single detection signal, which is then fed back to the vehicle controller by sensor 6. A single pressure sensor can be used to identify whether the bulldozer blade is in an operating state. The hydraulic actuator circuit itself does not require this electrical detection signal as a necessary condition for action. Therefore, sensor 6 mainly undertakes the functions of status feedback and control strategy input, which is beneficial for balancing detection functions and hydraulic operation reliability.
[0030] Based on the aforementioned basic structure, the backup valve assembly is further equipped with a hydraulically controlled check valve 7 and two overload relief valves 8. The inlet of the bulldozer blade directional valve 2 is connected to the output oil circuit of the main valve 1, and the return oil port is connected to the return oil circuit of the main valve 1. The hydraulically controlled check valve 7 is located at the inlet of the bulldozer blade directional valve 2. The hydraulically controlled check valve 7 is used to control the flow direction of the oil entering the backup valve assembly. When the corresponding pilot conditions are met, it allows the main pressure oil to enter the bulldozer blade directional valve 2, thereby making the oil supply relationship between the backup valve assembly and the main valve 1 clearer.
[0031] The two working ports of the bulldozer blade reversing valve 2 are each equipped with an overload protection branch. The lifting port is connected to the inlet of one overload relief valve 8, and the lowering port is connected to the inlet of the other overload relief valve 8. The outlet of the overload relief valve 8 is connected to the corresponding return oil circuit. When the bulldozer blade is subjected to external impact, the cylinder reaches its mechanical limit, or the pressure in a certain working chamber rises abnormally, the corresponding overload relief valve 8 can open after the set pressure is reached, releasing the high-pressure oil in that working branch to the return oil side and limiting the peak pressure of the working port. The overload relief valve 8 also has an oil replenishment structure. When the actuator chamber experiences a local low-pressure trend due to external load or rapid movement, oil can be replenished from the return oil side to the low-pressure working chamber to reduce the impact of cavitation and pressure changes on the stability of the operation.
[0032] Specifically, the main valve 1 has separate first and second return oil circuits. The return oil port of the bulldozer blade reversing valve 2 can be connected to the first return oil circuit, and the outlet of the first overload relief valve on the lifting side is also connected to the first return oil circuit; the outlet of the second overload relief valve on the lowering side is connected to the second return oil circuit of the main valve 1. With this connection method, the overload release oil from both working ports can be guided back to the corresponding return oil channels according to the original return oil zones of the main valve. If the main valve is only equipped with one common return oil circuit that meets the flow requirements, the outlets of the two overload relief valves 8 can also be connected to this return oil circuit. Both of the above arrangements utilize the existing return oil channels of the main valve 1, avoiding the need to set up an additional independent main return oil system.
[0033] The bulldozer blade directional valve 2 is preferably a three-position four-way hydraulically controlled directional valve. The three-position structure allows the valve core to have three working positions: raising, neutral, and lowering. When the operator does not depress the bulldozer blade foot valve 4, neither hydraulic port establishes effective pilot pressure, and the valve core remains or returns to the neutral position under reset action, preventing the main actuator from continuing to drive the bulldozer blade cylinder 3. When the raising foot pedal is depressed, the valve core moves to one working position, establishing a raising flow path; when the lowering foot pedal is depressed, the valve core moves to the other working position, establishing a lowering flow path. The three-position four-way structure is controlled by pilot pressure, eliminating the need for a separate mechanical lever in the cab to directly drive the main valve core, facilitating the later addition of foot pedal control.
[0034] A main shuttle valve 9 can also be installed between the bulldozer blade shuttle valve 5 and the sensor 6. The outlet of the bulldozer blade shuttle valve 5 is connected to one inlet of the main shuttle valve 9, and the outlet of the main shuttle valve 9 is connected to the sensor 6. In this way, the pilot pressure generated by raising or lowering the blade is first selected by the bulldozer blade shuttle valve 5, and then connected to the detection branch where the sensor is located through the main shuttle valve 9. The main shuttle valve 9 also utilizes the pressure selection function to allow the new pilot signal from the bulldozer blade to be integrated into the existing detection pipeline in the support area without backflow, which facilitates the centralized arrangement of sensors near the main valve 1, instead of having two sets of electrical sensors and wiring harnesses separately installed from the foot valve position in the cab.
[0035] During actual installation, the other inlet of the main shuttle valve 9 can maintain its connection with the existing hydraulic detection branch of the original vehicle, and be integrated without changing the corresponding functions of the original vehicle. Other detection methods can also be set, such as pressure detection of the bulldozer blade cylinder 3, and connected to the other inlet of the main shuttle valve 9.
[0036] In terms of structural layout, the system can be configured with a support bracket 10, with the main valve 1 and the backup valve connected in the rear area of the support bracket 10, the bulldozer blade foot valve 4 located in the front area of the support bracket 10, a rotary joint 11 located in the middle of the support bracket 10, and the sensor 6 located at the rear of the support bracket 10, close to the main valve and the corresponding shuttle valve assembly. This front, middle, and rear arrangement sequence allows for clear structural partitioning of the driver's operating end, the cross-rotation connection end, and the main valve oil supply end. It also enables the organization of hose routing based on the excavator frame and upper space, and reduces the crossing between high-pressure pipelines and operating components.
[0037] The rotary joint 11 forms a hydraulic connection node spanning the relative rotation interfaces of the upper and lower vehicles. Unlike ordinary hoses that directly cross the rotation center, the working oil or related control oil is transmitted through the corresponding oil passage of the rotary joint 11. As the upper vehicle continuously rotates relative to the lower vehicle, the oil passages inside the rotary joint remain connected through relative rotation, thus preventing the external hose from repeatedly twisting during the 360° rotation. Two backup oil passages in the central rotary joint can be used to transmit the bulldozer blade's working oil to the dual bulldozer blade cylinders 3 on the lower vehicle. This arrangement reduces the risk of interference from the rotary hose and hose, as well as long-term wear.
[0038] The sensor 6, bulldozer shuttle valve 5, or main shuttle valve 9 are centrally located at the rear end of the main valve bracket or on the lower side of the bracket, which facilitates assembly, inspection, and maintenance. The pilot pressure detection element is positioned close to the main valve area, shortening the local detection pipeline and preventing interference between the sensor and the cab foot pedal mechanism or surrounding flexible hoses. The bulldozer foot valve 4 is located at the front end of the bracket, facilitating mechanical operation with the foot pedal mechanism in the driver's position; the main valve 1 and the spare valve are located at the rear end, allowing direct use of the original vehicle's main fuel supply and return interfaces.
[0039] The system includes two bulldozer blade cylinders 3 connected in parallel, with each cylinder acting on the left and right sides of the bulldozer blade assembly, respectively. A bulldozer blade directional valve 2 is connected to the two cylinders 3 via a hydraulic lock 12, which is located near the cylinders on the pipeline. When raising the blade, pressurized oil from the bulldozer blade directional valve 2 enters the corresponding working chamber of the two cylinders via the hydraulic lock 12, while oil from the other working chamber returns to the directional valve via the hydraulic lock 12 under pilot-operated conditions. When lowering the blade, the inlet and outlet oil connections on both sides are switched accordingly.
[0040] The hydraulic lock 12 preferably adopts a bidirectional hydraulically controlled one-way structure to lock the two working chambers of the bulldozer blade cylinder 3 separately. When the bulldozer blade directional valve 2 is in the neutral position and the pilot pressure is released, the one-way valve in the hydraulic lock 12 cuts off the oil flowing out of the cylinder, making it less likely for oil to continuously leak from both chambers of the cylinder. Therefore, it can reduce the risk of the bulldozer blade slowly descending under its own weight. When it is necessary to raise or lower the blade, the pressure oil entering one working chamber simultaneously creates a hydraulically controlled opening condition, causing the hydraulically controlled one-way valve on the other side to open, allowing the return oil to be discharged, thereby releasing the lock when the action is required.
[0041] Furthermore, the return port of the travel pilot valve is connected to the return oil circuit of the main valve 1, and a bypass shut-off valve 13 is installed on this return oil circuit. When the bulldozer foot pedal is depressed, the pilot pressure output by the bulldozer foot valve 4, in addition to controlling the bulldozer reversing valve 2, also sends a switching signal to the bypass shut-off valve 13, causing the bypass shut-off valve 13 to switch from the normal position to the shut-off state, thereby closing or throttling the corresponding travel pilot return oil bypass. By reducing the path of the pilot oil directly discharged back to the oil tank via the bypass, the required pilot control pressure can be maintained during bulldozer operation, and in conjunction with the main valve bypass shut-off logic, more effective flow can be used for the bulldozer execution circuit.
[0042] For the main valve 1, which has a first return oil circuit and a second return oil circuit, a first bypass shut-off valve can be installed on the first return oil circuit, and a second bypass shut-off valve can be installed on the second return oil circuit. Both valves' hydraulic ports simultaneously receive control signals generated by the bulldozer blade's foot pedal operation. Thus, regardless of whether the blade is raised or lowered, the two bypass shut-off valves synchronously switch positions according to the same foot pedal state, coordinating the shut-off of the corresponding two bypass return oil channels. When the foot pedal is released, the control pressure disappears, the two bypass shut-off valves reset, restoring the original travel pilot return oil path.
[0043] The bypass disconnection logic does not replace hydraulic control with electrical signals, but rather directly utilizes the foot pedal pilot pressure to create hardware switching conditions. When the travel and dozer blade need to move simultaneously, the foot pedal pilot pressure, on the one hand, causes the dozer blade reversing valve 2 to enter the working position, and on the other hand, drives the bypass disconnection valve 13 to disconnect the corresponding bypass, ensuring the dozer blade control pressure and execution flow at the hydraulic circuit level. Simultaneously, sensor 6 feeds back the dozer blade's operating status to the vehicle controller, which can then execute corresponding power or torque strategies based on this feedback. Therefore, the hydraulic bypass disconnection and the electronic control status feedback form two independent yet collaborative paths.
[0044] The bypass shut-off valve 13 is preferably a two-position, two-way hydraulically controlled directional valve. The two positions correspond to the bypass on and bypass off states, respectively. The two ports are connected in series to the return bypass that needs to be controlled, and the hydraulically controlled port receives the pilot signal from the bulldozer foot valve 4. Both the lifting and lowering output ports of the bulldozer foot valve 4 can provide pressure to the hydraulically controlled branch of the bypass shut-off valve 13. Therefore, regardless of whether the operator is lifting or lowering the bulldozer, the bypass shut-off valve 13 can be switched by simply pressing the foot pedal.
[0045] When the foot pedal is released, both the lifting and lowering output ports are depressurized, and the hydraulic control port of the bypass shut-off valve 13 loses its switching pressure. Under the action of the reset element, it returns to the bypass conduction state, allowing the travel pilot system to resume normal oil return. Therefore, the bypass shut-off only intervenes during actual bulldozer blade operation, without requiring the operator to manually activate the switch. For structures with two bypass shut-off valves, both can share the same pilot control signal or be controlled in parallel by the same set of lifting and lowering signals, thus ensuring consistent switching timing.
[0046] A one-way throttle valve 14 is installed at the hydraulic control port of the bypass shut-off valve 13 to control the flow rate in different directions during the pilot pressure establishment and release process. In the pilot oil inlet direction, such as when the bulldozer blade is lowering and the bypass shut-off action needs to be established smoothly, the oil enters the hydraulic control port of the bypass shut-off valve 13 after passing through the throttle channel, so that the hydraulic control pressure is established at a controlled speed, thereby slowing down the switching rate of the bypass shut-off valve core and reducing the hydraulic shock when the bulldozer blade approaches the ground or the load changes; when the operator releases the foot pedal, the oil in the hydraulic control chamber can be quickly depressurized through the one-way bypass inside the one-way throttle valve 14, so that the bypass shut-off valve 13 can be reset in time.
[0047] A forward-directing tubular check valve 15 is installed at the hydraulic control port of main valve 1. When pilot control oil enters the hydraulic control branch of the main valve in the specified direction, the tubular check valve 15 allows the oil to pass through, ensuring that the corresponding control chamber of the main valve can obtain the required pilot pressure. In the neutral position, the tubular check valve 15 forms a reverse cutoff, reducing the reverse leakage of oil in the pilot chamber and the pressure crosstalk between different valve connections. By maintaining the stability of the control chamber pressure boundary in the neutral position, valve core drift and bulldozer blade self-slippage caused by pipeline leakage or cross-connection pressure interference can be suppressed. The one-way throttle valve 14 and the tubular check valve 15 work together to balance the smooth landing of the bulldozer blade, bypass cut-off response, and reliability of neutral position locking.
[0048] Based on the above specific implementation methods, the pilot oil supply of the travel main valve is first provided to the travel pilot valve. The P port and T port of the travel pilot valve are then connected to the P port and T port of the bulldozer foot valve 4, respectively, so that the bulldozer foot valve 4 can directly utilize the original vehicle pilot pressure oil source without the need for a separate pilot pump. The P port oil inlet branch of the bulldozer foot valve 4 is equipped with a 100μm pilot oil filter to reduce the possibility of impurities entering the foot valve and causing jamming of subsequent small-diameter pilot components.
[0049] Sensor 6 can also be used to assist in fault diagnosis. For example, if the vehicle controller determines that a bulldozer pedal action should occur based on operating conditions, but sensor 6 does not detect pilot pressure feedback for an extended period, it can be used as a basis for checking for pilot circuit faults such as damaged pedal valve, detached or blocked pilot hose. Conversely, if the sensor continuously detects pressure when the operator has not pressed the pedal and the control logic is in an inactive state, it can prompt the inspection of a stuck pedal valve, a malfunctioning return spring, or abnormal residual pressure in the pilot circuit. The specific fault code, duration threshold, and alarm method are determined by the vehicle controller's software strategy.
[0050] It should be noted that sensor 6 in this system primarily serves as status feedback rather than hydraulic actuation authorization. The bulldozer blade directional valve 2 and bypass shut-off valve 13 are directly driven by foot-operated pilot pressure, and the main pressure oil for the bulldozer blade cylinder 3 is also directly supplied by the main valve 1 and the backup valve assembly. Therefore, even if sensor 6 or its electrical circuit malfunctions, as long as the hydraulic circuit itself is functioning normally, the operator can still perform the raising and lowering actions of the bulldozer blade. This design relatively decouples the electronic control identification function from the basic hydraulic actuation function, increasing status monitoring capabilities while avoiding making a single electrical component an essential link in all bulldozer blade movements.
[0051] Since the spare valve coupling of main valve 1 is used as the main directional control element of the bulldozer blade, there is no need to connect an independent main directional control valve in series outside of main valve 1. Therefore, provided that the interface conditions of the target model are met, the modification of the new valve block and main high-pressure pipeline can be reduced, thus reducing the number of joints and potential leakage points. This modification approach can avoid occupying the original breaker's functions when the specific configuration allows, and has the advantages of requiring less modification to the original vehicle parts, better action response, and easy restoration of the original vehicle pipeline.
[0052] In addition to the aforementioned bulldozer blade hydraulic control system, a specific embodiment of the present invention also provides a tracked excavator including the aforementioned bulldozer blade hydraulic control system. The structure of other parts of the tracked excavator can be found in the prior art, and will not be described in detail here.
[0053] The above provides a detailed description of the bulldozer blade hydraulic control system and the tracked excavator provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.
Claims
1. A hydraulic control system for a bulldozer blade, the system comprising: The system includes a main valve (1), a backup valve assembly, a bulldozer blade cylinder (3), and a bulldozer blade foot valve (4). The backup valve assembly includes a bulldozer blade reversing valve (2). The main valve (1) is connected to the inlet and outlet of the bulldozer blade reversing valve (2). The lifting port of the bulldozer blade reversing valve (2) is connected to the rodless chamber of the bulldozer blade cylinder (3), and the lowering port of the bulldozer blade reversing valve (2) is connected to the rod chamber of the bulldozer blade cylinder (3). The bulldozer blade foot valve (4) The lifting output port of the bulldozer blade is connected to the lifting hydraulic control port of the bulldozer blade reversing valve (2), the lowering output port of the bulldozer blade foot valve (4) is connected to the lowering hydraulic control port of the bulldozer blade reversing valve (2), the lifting output port and the lowering output port of the bulldozer blade foot valve (4) are respectively connected to the two inlets of the bulldozer blade shuttle valve (5), and the outlet of the bulldozer blade shuttle valve (5) is connected to the sensor (6). The vehicle controller determines the working status of the bulldozer blade based on the detection result of the sensor (6).
2. The hydraulic control system for a dozer blade according to claim 1, characterized by, The backup valve assembly also includes a hydraulically controlled check valve (7) and two overload relief valves (8). The oil inlet of the bulldozer blade reversing valve (2) is connected to the output oil circuit of the main valve (1). The oil return port of the bulldozer blade reversing valve (2) is connected to the oil return circuit of the main valve (1). The hydraulically controlled check valve (7) is installed at the oil inlet of the bulldozer blade reversing valve (2). The lifting oil port and lowering oil port of the bulldozer blade reversing valve (2) are respectively connected to the inlets of the two overload relief valves (8). The outlet of the overload relief valve (8) is connected to the oil return circuit. The overload relief valve (8) is equipped with an oil replenishment structure.
3. The hydraulic control system for a dozer blade of claim 2, wherein, The bulldozer blade reversing valve (2) is a three-position four-way hydraulic reversing valve.
4. The hydraulic control system for a dozer blade of claim 2, wherein, Includes a main shuttle valve (9), the outlet of the bulldozer shuttle valve (5) is connected to one inlet of the main shuttle valve (9), and the outlet of the main shuttle valve (9) is connected to the sensor (6).
5. The hydraulic control system for a dozer blade of claim 4, wherein, The bracket (10) includes a main valve (1) and a backup valve connected to the rear end of the bracket (10), a bulldozer foot valve (4) is installed at the front end of the bracket (10), a rotary joint (11) is provided in the middle of the bracket (10), the backup valve is connected to the bulldozer foot valve (4) through the rotary joint (11), and the sensor (6) is installed at the rear end of the bracket (10).
6. The hydraulic control system for a dozer blade of claim 2, wherein, It includes two bulldozer blade cylinders (3) arranged in parallel, and the bulldozer blade reversing valve (2) is connected to the bulldozer blade cylinders (3) through a hydraulic lock (12).
7. The hydraulic control system for a dozer blade according to any one of claims 2 to 6, characterized by, The return port of the travel pilot valve is connected to the return oil circuit, which is equipped with a bypass shut-off valve (13). When the foot pedal is pressed, a switching signal is sent to the bypass shut-off valve (13) to cut off the return oil circuit.
8. The hydraulic control system for a dozer blade of claim 7, wherein, The bypass shut-off valve (13) is a two-position two-way hydraulic control directional valve. The lifting and lowering output ports of the bulldozer foot valve (4) are connected to the hydraulic control ports of the bypass shut-off valve (13).
9. The hydraulic control system for a dozer blade of claim 8, wherein, The bypass shut-off valve (13) is equipped with a one-way throttle valve (14) at its hydraulic control port, and the main valve (1) is equipped with a forward-directing pipe-type one-way valve (15) at its hydraulic control port.
10. A track excavator characterised in that, Includes the bulldozer blade hydraulic control system as described in any one of claims 1 to 9.