A pressure self-adaptive control system of a high-pressure sewer cleaning vehicle

Abstract

The present application belongs to the technical field of municipal environmental sanitation equipment control, and provides a sewer high-pressure cleaning vehicle pressure self-adaptive control system, which comprises a multi-source pressure sensing module, a double-actuator adjusting module and a main control unit; the multi-source pressure sensing module comprises a pump outlet pressure sensor, a nozzle back pressure sensor, a backwater pressure sensor, a flow sensor and a reel speed encoder, the pump outlet pressure sensor is arranged at the water outlet of the high-pressure plunger pump, the nozzle back pressure sensor is arranged at the connection between the high-pressure rubber pipe and the nozzle, and the backwater pressure sensor is arranged at the backwater branch of the proportional overflow valve; according to the present application, the accurate positioning of the pipeline blockage position is realized through multi-source pressure sensing and pressure wave time delay calculation, the pressure feedforward decision is made in combination with the phase plane working condition identification and the dynamic compensation model of the along-path loss, and the self-adaptive adjustment of the pressure is realized through the double-actuator cooperation and the jet reaction force-feeding coupled control.

Description

Technical Field

[0001] This invention belongs to the field of municipal sanitation equipment control technology, and particularly relates to a pressure adaptive control system for a high-pressure cleaning vehicle for sewers. Background Technology

[0002] High-pressure sewer cleaning trucks are core equipment for the maintenance and dredging of urban drainage pipes. They use a high-pressure plunger pump to pressurize water in a tank, which is then delivered to the nozzles via high-pressure hoses. The high-pressure jets from the nozzles flush away and remove deposits and blockages from the inner walls of the pipes. In actual operation, the degree of blockage, pipe diameter, number of bends, and type of deposits vary considerably. If the cleaning pressure cannot be adaptively adjusted to the working conditions, problems may arise such as excessive pressure in mildly blocked sections leading to water and energy waste, and insufficient pressure in severely blocked sections resulting in incomplete dredging.

[0003] For example, Chinese Patent (Publication No.: CN111197294A) discloses a cleaning vehicle and its water circuit control device. This device includes a water pressure setting device, an information processing unit, a motor controller, and a pressure sensor connected to the information processing unit, connected in sequence. The pressure sensor detects the actual water pressure output from the plunger pump. The information processing unit compares the deviation between the actual value and the set value. The motor controller adjusts the motor speed of the plunger pump in real time according to the deviation, making the water pressure approach the set value. This solution achieves single-point closed-loop constant control of the pump outlet pressure. However, it is designed for road cleaning operations, and by only setting a single pressure sensor at the plunger pump outlet, it cannot sense the actual back pressure changes at the nozzle, nor can it identify the location and condition of blockages inside the sewer pipes. Furthermore, this solution only changes the pressure through a single actuator adjusting the motor speed, resulting in limited response speed. It is prone to water hammer impact when encountering sudden blockages or hose bends. It also does not consider multi-objective collaborative optimization under vehicle constraints such as water tank level and engine load, nor does it address the coupling control between the nozzle feed speed and the jet reaction force.

[0004] The pressure control of existing high-pressure cleaning trucks for sewers mainly has the following problems:

[0005] Firstly, the pressure sensing source is singular, with a pressure sensor only installed at the pump outlet, which cannot reflect the actual back pressure at the nozzle and the location of pipe blockage, causing the actual cleaning pressure to deviate from the target value.

[0006] Secondly, single actuator regulation, which changes pressure solely by motor speed, makes it difficult to balance response speed and regulation accuracy, and results in significant overflow losses under low-pressure, high-flow conditions.

[0007] Third, it lacks the ability to identify pipeline operating conditions and provide feedforward adjustment. Pressure regulation lags behind changes in operating conditions, resulting in brief periods of insufficient pressure or pressure surges when the nozzle moves from a slightly blocked section to a heavily blocked section.

[0008] Fourth, the system does not consider the coordinated protection of vehicle constraints and sudden working conditions. Maintaining high pressure output when the water tank level is too low or the engine load is too high may damage the equipment. There is no rapid pressure relief mechanism when the nozzle is suddenly blocked, and the nozzle feed speed is not linked to the jet reaction force, which may easily cause the nozzle to jam or the hose to become tangled.

[0009] Therefore, a pressure adaptive control system for high-pressure cleaning trucks for sewers is needed to solve the above problems. Summary of the Invention

[0010] The purpose of this invention is to provide a pressure adaptive control system for a high-pressure cleaning vehicle for sewers to solve the problems mentioned in the background art.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] An adaptive pressure control system for a high-pressure cleaning truck for sewers includes a multi-source pressure sensing module, a dual-actuator adjustment module, and a main control unit. The multi-source pressure sensing module includes a pump outlet pressure sensor, a nozzle back pressure sensor, a return water pressure sensor, a flow sensor, and a reel speed encoder. The pump outlet pressure sensor is located at the outlet of the high-pressure plunger pump. The nozzle back pressure sensor is located at the connection between the high-pressure hose and the nozzle. The return water pressure sensor is located in the return water branch of the proportional overflow valve. The flow sensor is connected in series in the outlet pipeline. The outlet pipeline also includes a filter and a check valve. The filter is located between the outlet of the high-pressure plunger pump and the flow sensor. The reel speed encoder is installed on the shaft of the reel.

[0013] The dual actuator regulating module includes a frequency converter drive unit and a proportional relief valve. The output end of the frequency converter drive unit is connected to a drive motor. The output shaft of the drive motor is connected to the input shaft of the high-pressure plunger pump through a coupling. The proportional relief valve is connected in series in the return water branch.

[0014] The input terminals of the main control unit are respectively connected to the signal output terminals of the pump outlet pressure sensor, the nozzle back pressure sensor, the return water pressure sensor, the flow sensor, and the reel speed encoder. The output terminals of the main control unit are respectively connected to the control terminals of the frequency converter and the proportional relief valve.

[0015] The main control unit is equipped with a pressure wave delay calculation submodule. The signal input terminal of the pressure wave delay calculation submodule is connected to the signal output terminals of the pump outlet pressure sensor and the nozzle back pressure sensor. The main control unit outputs adjustment signals to the frequency conversion drive unit and the proportional relief valve based on the blockage position signal output by the pressure wave delay calculation submodule and the signal from the multi-source pressure sensing module.

[0016] In a further technical solution, the main control unit is also equipped with a working condition identification submodule, which includes a phase plane analysis module. The signal input terminal of the phase plane analysis module is connected to the signal output terminals of the flow sensor and the nozzle back pressure sensor, and the identification result output terminal of the phase plane analysis module is connected to the pressure decision input terminal of the main control unit. The phase plane analysis module maps the pressure and flow signals to the phase plane and identifies the pipeline working condition category through the morphological characteristics of the phase trajectory.

[0017] In a further technical solution, the main control unit is also equipped with a friction loss compensation model module. The signal input terminal of the friction loss compensation model module is connected to the signal output terminals of the flow sensor and the reel speed encoder. The compensation pressure output terminal of the friction loss compensation model module is connected to the pressure decision input terminal of the main control unit. The friction loss compensation model module calculates the friction pressure loss based on the real-time flow rate, the high-pressure hose discharge length, and the hose wear coefficient, and outputs the compensated effective jet pressure of the nozzle.

[0018] In a further technical solution, the main control unit also stores a pressure level mapping table. The query input end of the pressure level mapping table is connected to the recognition result output end of the working condition identification submodule, and the target pressure output end of the pressure level mapping table is connected to the pressure decision input end of the main control unit. The pressure level mapping table records the target pressure value and target flow value corresponding to different working condition categories. The target pressure value obtained by querying is input to the pressure decision input end of the main control unit.

[0019] In a further technical solution, the dual actuator regulating module also includes an electromagnetic pressure relief valve, which is connected in parallel to the return water branch at both ends of the proportional overflow valve. The main control unit is equipped with a pressure change detection circuit. The signal input terminal of the pressure change detection circuit is connected to the signal output terminals of the pump outlet pressure sensor and the nozzle back pressure sensor. The trigger output terminal of the pressure change detection circuit is connected to the control terminal of the electromagnetic pressure relief valve.

[0020] A further technical solution also includes a reel drive motor, the output shaft of which is connected to the rotating shaft of the reel via a reducer. The control end of the reel drive motor is connected to the feed control output end of the main control unit. The main control unit calculates the jet reaction force based on the signal from the nozzle back pressure sensor and the signal from the flow sensor, and outputs a speed adjustment signal to the reel drive motor. When the jet reaction force exceeds a preset threshold, the main control unit outputs a signal to the reel drive motor to reduce the speed or pause pipe take-up.

[0021] A further technical solution also includes a water tank level sensor and an engine load sensor. The water tank level sensor is located inside the water tank, and the engine load sensor is connected to the output terminal of the vehicle engine's ECU. The signal output terminals of the water tank level sensor and the engine load sensor are respectively connected to the input terminal of the main control unit. The main control unit limits the maximum output pressure based on the water tank level and engine load signals.

[0022] A further technical solution also includes a human-machine interface touch screen, which is connected to the main control unit via a communication bus. The human-machine interface touch screen is equipped with a pressure setting interface, a working condition display interface, and a parameter configuration interface. The working condition display interface displays the blockage location, working condition type, current pressure, and flow data in real time.

[0023] A further technical solution also includes a wireless communication module, which is connected to the communication port of the main control unit and interacts with the remote dispatching platform to upload operation data, congestion location information and equipment status to the remote dispatching platform, and receive remotely issued dispatching instructions and parameter configurations.

[0024] A further technical solution involves a dual-pump parallel configuration of the high-pressure plunger pumps, comprising a first high-pressure plunger pump and a second high-pressure plunger pump. The inlet of each high-pressure plunger pump is connected to a water tank via a first inlet valve and a second inlet valve, respectively. The outlet of each high-pressure plunger pump is connected to a junction connector via a first outlet branch pipe and a second outlet branch pipe, respectively. A first pump outlet check valve is installed on the first outlet branch pipe, and a second pump outlet check valve is installed on the second outlet branch pipe. The junction connector connects to the outlet pipeline. Each high-pressure plunger pump is equipped with an independent first drive motor, a second drive motor, a first frequency converter, and a second frequency converter. A first pump outlet pressure sensor and a second pump outlet pressure sensor are installed at the outlet of each high-pressure plunger pump. The output of the main control unit is connected to the control terminals of the first and second frequency converters, respectively, and the input of the main control unit is connected to the signal output terminals of the first and second pump outlet pressure sensors, respectively. The main control unit selects single-pump operation or dual-pump parallel operation based on the operating condition identification result.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] This invention, by installing high-frequency pressure sensors at the pump outlet and nozzle end respectively, utilizes the time delay difference of pressure wave propagation within the high-pressure hose, combined with the hose extension length calculated by the reel speed encoder and the fixed length of the water outlet pipe, to accurately locate the specific position of the pipe blockage point in the pipe. This allows the system to not only know whether the pressure is abnormal, but also to know where the blockage is, providing a location basis for precise adaptive pressure adjustment. This helps to solve the problem of the single pressure sensing source in the background technology, which cannot reflect the true working condition of the pipeline, and improves the targeting and efficiency of dredging operations.

[0027] This invention maps pressure and flow signals to the phase plane using a pressure-flow phase plane analysis module. It identifies pipeline operating conditions by utilizing morphological features such as small-radius limit loops, aperiodic drift, or large-radius limit loops in the phase trajectory. Compared to traditional threshold judgment or spectrum analysis methods, this approach is more robust in identifying complex operating conditions. Simultaneously, it combines a dynamic friction loss compensation model to calculate friction pressure loss based on real-time flow, hose discharge length, and wear coefficient, accurately estimating the effective jet pressure of the nozzle. This avoids actual pressure deviations caused by controlling solely based on pump outlet pressure, helping to solve the problems of lack of operating condition identification and feedforward adjustment capabilities, and pressure regulation lag in the prior art, thus improving the accuracy of pressure control and the consistency of unblocking effects.

[0028] This invention employs a dual actuator system of variable frequency drive unit and proportional relief valve for coordinated regulation. When the pressure is adjusted significantly, variable frequency volume regulation is used to reduce overflow loss. When the pressure is adjusted slightly, proportional relief bypass regulation is used to improve response speed. The two actuators work together to balance energy efficiency and responsiveness, which helps to solve the problem in the prior art where it is difficult to balance single actuator regulation, response speed and regulation accuracy.

[0029] This invention utilizes an electromagnetic pressure relief valve and a pressure surge detection circuit to provide rapid pressure relief protection under sudden operating conditions, suppressing water hammer effects. It incorporates the vehicle's overall status into pressure decision-making through a water tank level sensor and an engine load sensor, automatically limiting the maximum output pressure under resource-constrained conditions. Furthermore, it employs a reel drive motor to achieve coupled control of the jet reaction force and nozzle feed speed. When the jet reaction force is excessive, it automatically reduces the hose reel speed or pauses feed, preventing nozzle jamming or hose tangling. This invention helps address the issues in the prior art where the coordinated protection against vehicle constraints and sudden operating conditions was not considered, and the feed speed was not linked to the jet reaction force, thereby improving the safety, reliability, and sustainability of equipment operation.

[0030] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0031] Figure 1 This is a block diagram of the overall waterway architecture of the present invention;

[0032] Figure 2 This is a block diagram of the dual-pump parallel water circuit architecture of the present invention;

[0033] Figure 3 This is a block diagram showing the architecture of the main control unit of the present invention.

[0034] In the diagram: 1. High-pressure plunger pump; 1a. First high-pressure plunger pump; 1b. Second high-pressure plunger pump; 2. Drive motor; 2a. First drive motor; 2b. Second drive motor; 3. Pump outlet pressure sensor; 3a. First pump outlet pressure sensor; 3b. Second pump outlet pressure sensor; 4. High-pressure hose; 5. Nozzle; 6. Nozzle back pressure sensor; 7. Proportional overflow valve; 8. Return water pressure sensor; 9. Flow sensor; 10. Variable frequency drive unit; 10a. First variable frequency drive unit; 10b. Second variable frequency drive unit; 11. Main control unit; 12. Water tank; 13. Winding reel; 14. Winding reel speed encoder; 15. Electromagnetic pressure relief valve; 16. Water tank liquid... 17. Position sensor; 18. Engine load sensor; 19. Human-machine interface touch screen; 20. Wireless communication module; 21. Operating condition identification submodule; 22. Pressure level mapping table; 23. Return water branch; 24. Outlet water pipe; 25. Filter; 26. Check valve; 27. Pressure wave delay calculation submodule; 28. Reel drive motor; 29. ​​Friction loss compensation model module; 30. Phase plane analysis module; 31. Connecting joint; 32. Coupling; 33a. Reducer; 34a. First inlet valve; 34b. Second inlet valve; 35a. First outlet branch pipe; 36b. Second outlet branch pipe; 37a. First pump outlet check valve; 38b. Second pump outlet check valve. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0037] Example 1

[0038] like Figure 1-3 As shown, this embodiment of the invention provides a pressure adaptive control system for a high-pressure cleaning vehicle for sewers, including a multi-source pressure sensing module, a dual-actuator adjustment module, and a main control unit 11.

[0039] In this embodiment, the multi-source pressure sensing module includes a pump outlet pressure sensor 3, a nozzle back pressure sensor 6, a return water pressure sensor 8, a flow sensor 9, and a reel speed encoder 14. The inlet of the high-pressure plunger pump 1 is connected to the water tank 12 via a pipe, and the outlet of the high-pressure plunger pump 1 is connected to the outlet pipe 23. The end of the outlet pipe 23 is connected to a high-pressure hose 4, which is wound around the reel 13 and extends into the sewer pipe. The end of the high-pressure hose 4 is connected to the nozzle 5. Pump outlet pressure sensor 3 is installed at the outlet flange of high-pressure plunger pump 1 to detect the pump's output pressure; nozzle back pressure sensor 6 is installed at the connection joint between high-pressure hose 4 and nozzle 5 to detect the actual back pressure at the nozzle inlet; flow sensor 9 is connected in series in the outlet pipe 23, located downstream of pump outlet pressure sensor 3, to detect the real-time outlet flow rate of the system; reel speed encoder 14 is installed at the end of the shaft of reel 13. When reel 13 rotates, it drives the main shaft of reel speed encoder 14 to rotate synchronously. Reel speed encoder 14 outputs pulse signals proportional to the rotation angle. The main control unit 11 calculates the release length and retraction speed of high-pressure hose 4 by counting these pulse signals. The inlet of proportional overflow valve 7 is connected to outlet pipe 23 through return water branch 22, and the outlet of proportional overflow valve 7 is connected to water tank 12. Return water pressure sensor 8 is installed on the return water branch 22 at the inlet of proportional overflow valve 7 to detect return water pressure. The outlet pipe 23 is also equipped with a filter 24 and a one-way valve 25. The filter 24 is located between the outlet of the high-pressure plunger pump 1 and the flow sensor 9, and is used to filter impurities in the water to protect the downstream sensor and nozzle 5. The one-way valve 25 is located downstream of the flow sensor 9 and is used to prevent high-pressure water from flowing back.

[0040] The dual-actuator regulating module includes a frequency converter drive unit 10 and a proportional relief valve 7. The output shaft of the drive motor 2 is connected to the input shaft of the high-pressure plunger pump 1 via a coupling 31. The power output terminal of the frequency converter drive unit 10 is connected to the power supply terminal of the drive motor 2. The frequency converter drive unit 10 adjusts the speed of the drive motor 2 by changing the frequency of the output power, thereby changing the displacement of the high-pressure plunger pump 1. The proportional relief valve 7 is connected in series in the return water branch 22. By changing the valve core opening, it adjusts the amount of water discharged into the return water tank 12 through the return water branch 22, thereby regulating the pressure in the outlet water pipe 23.

[0041] The main control unit 11 is an embedded controller installed in the control cabinet of the cleaning vehicle. The analog input terminals of the main control unit 11 are connected to the signal output terminals of the pump outlet pressure sensor 3, the nozzle back pressure sensor 6, the return water pressure sensor 8, and the flow sensor 9 via shielded signal lines. The pulse count input terminal of the main control unit 11 is connected to the signal output terminal of the reel speed encoder 14. The first analog output terminal of the main control unit 11 is connected to the speed setpoint terminal of the frequency converter drive unit 10, and the second analog output terminal of the main control unit 11 is connected to the electromagnet control terminal of the proportional relief valve 7. The main control unit 11 includes a pressure wave delay calculation submodule 26, whose signal input terminals are connected to the signal output terminals of the pump outlet pressure sensor 3 and the nozzle back pressure sensor 6.

[0042] During operation, when there is a blockage in the pipeline, the high-pressure jet from nozzle 5 impacts the blockage, generating pressure fluctuations. These pressure fluctuations are transmitted in the form of pressure waves along the water in the high-pressure hose 4 to both ends. One end is transmitted to the nozzle back pressure sensor 6, and the other end is transmitted through the high-pressure hose 4 and the outlet pipe 23 to the pump outlet pressure sensor 3. The pressure wave delay calculation submodule 26 processes the signals collected by the two sensors as follows: First, the original signals collected by the pump outlet pressure sensor 3 and the nozzle back pressure sensor 6 are de-DC and normalized respectively to eliminate the influence of signal amplitude differences; then, using the signal from the nozzle back pressure sensor 6 as the reference signal and the signal from the pump outlet pressure sensor 3 as the delay signal, the sliding dot product of the two normalized signals is calculated with different time offsets, i.e., cross-correlation operation; when the sliding dot product reaches its maximum value, the corresponding time offset is the transmission delay between the two pressure wave signals from the same source. The pressure wave delay calculation submodule 26 multiplies the conduction delay by the speed of sound propagating in the high-pressure hose 4 to obtain the path difference of the pressure wave from the blockage point to the two sensors. Combined with the length of the high-pressure hose 4 accumulated by the reel speed encoder 14 and the fixed length of the outlet pipe 23, it calculates the position of the blockage point relative to the nozzle 5 and the absolute position of the blockage point in the pipeline. Based on the blockage position signal output by the pressure wave delay calculation submodule 26, the main control unit 11, combined with the pump outlet pressure, nozzle back pressure, return water pressure, and flow rate signals, determines the severity of the blockage and the pipeline condition. Simultaneously, it outputs adjustment signals to the frequency converter drive unit 10 and the proportional relief valve 7. During the large pressure adjustment phase, the main control unit 11 primarily adjusts the speed of the frequency converter drive unit 10, while the proportional relief valve 7 maintains a small opening to reduce overflow loss. During the fine-tuning phase after pressure stabilization, the main control unit 11 maintains the speed of the frequency converter drive unit 10 essentially constant, achieving fine pressure correction through fine-tuning the opening of the proportional relief valve 7.

[0043] Example 2

[0044] The difference between this embodiment and embodiment 1 is that the main control unit 11 is further provided with a working condition identification submodule 20, which includes a phase plane analysis module 29.

[0045] In this embodiment, the signal input terminal of the phase plane analysis module 29 is connected to the signal output terminals of the flow sensor 9 and the nozzle back pressure sensor 6. The phase plane analysis module 29 constructs a two-dimensional phase plane with the flow signal as the abscissa and the nozzle back pressure signal as the ordinate, and maps the real-time collected flow-pressure data points onto this phase plane to form a phase trajectory. When the pipeline is under mild blockage, the jet can smoothly remove deposits, and the system oscillates slightly around the equilibrium point. The phase trajectory exhibits a small-radius limiting loop shape around a certain equilibrium point. When the pipeline is under severe blockage, the jet is obstructed, resulting in increased pressure and decreased flow. The system deviates from the original equilibrium point, and the phase trajectory exhibits a non-periodic drift towards the high-pressure, low-flow region. When the nozzle 5 passes through a pipe bend, the flow field is periodically disturbed, and the phase trajectory exhibits a closed limiting loop shape with a larger radius. The phase plane analysis module 29 extracts characteristic parameters such as the limit loop radius, drift direction and oscillation period of the phase trajectory to identify the current pipeline operating condition category, including light blockage, moderate blockage, heavy blockage, pipe diameter change and bend passage, etc. The identification results are output to the pressure decision input terminal of the main control unit 11.

[0046] Example 3

[0047] The difference between this embodiment and embodiment 1 is that the main control unit 11 is also equipped with a friction loss compensation model module 28 and a pressure level mapping table 21.

[0048] In this embodiment, the signal input terminal of the friction loss compensation model module 28 is connected to the signal output terminals of the flow sensor 9 and the reel speed encoder 14. The friction loss compensation model module 28 has a built-in friction resistance calculation formula. It calculates the friction pressure loss value of the high-pressure hose 4 and the outlet pipe 23 using the real-time flow rate, the discharge length of the high-pressure hose 4 accumulated by the reel speed encoder 14, and the hose wear coefficient as inputs. The initial value of the hose wear coefficient is calibrated according to the factory parameters of the high-pressure hose 4. During use, it can be corrected according to the service life of the hose through the parameter configuration interface of the human-machine interface touch screen 18. Alternatively, during the system's periodic maintenance, the wear coefficient can be back-calculated and updated to the parameter area of ​​the main control unit 11 after measuring the friction loss in a calibration experiment with a known pipe diameter and set flow rate. The main control unit 11 subtracts the friction pressure loss value output by the friction loss compensation model module 28 from the pump outlet pressure detected by the pump outlet pressure sensor 3 to obtain the compensated effective jet pressure of the nozzle, which is used as the feedback quantity for pressure closed-loop control. The pressure level mapping table 21 is stored in the non-volatile memory of the main control unit 11. The table records the target pressure and target flow values ​​corresponding to different operating conditions, such as light blockage, moderate blockage, heavy blockage, pipe diameter reduction, and elbow passage. The operating condition category output by the operating condition identification submodule 20 serves as the query index for the pressure level mapping table 21. The retrieved target pressure and target flow values ​​are input into the pressure decision-making stage of the main control unit 11. Based on these target values, the main control unit 11 adjusts the outputs of the frequency converter drive unit 10 and the proportional relief valve 7 in advance to achieve feedforward regulation.

[0049] Example 4

[0050] The difference between this embodiment and embodiment 1 is that the dual actuator regulating module also includes an electromagnetic pressure relief valve 15, and the main control unit 11 is equipped with a pressure change detection circuit.

[0051] In this embodiment, the electromagnetic pressure relief valve 15 is a normally closed two-position two-way electromagnetic valve. Its inlet is connected to the return water branch 22 of the proportional relief valve 7 via a pipe, and its outlet is connected to the return water pipe between the outlet of the proportional relief valve 7 and the water tank 12 via a pipe. That is, the electromagnetic pressure relief valve 15 and the proportional relief valve 7 are connected in parallel. The diameter of the electromagnetic pressure relief valve 15 is larger than the rated flow capacity of the proportional relief valve 7 to ensure that the fluid in the high-pressure pipeline can be quickly discharged when fully open. The pressure change detection circuit in the main control unit 11 includes a differential amplifier circuit, a comparator, and a monostable trigger. The signals from the pump outlet pressure sensor 3 and the nozzle back pressure sensor 6 are processed by the differential amplifier circuit and then input to the inverting terminal of the comparator. The non-inverting terminal of the comparator is connected to a preset pressure change rate threshold voltage. When the pump outlet pressure or nozzle back pressure experiences an abnormal surge within a short period, such as when nozzle 5 suddenly becomes blocked, high-pressure hose 4 bends, or the operator presses the emergency stop button, the rate of change signal output by the differential amplifier circuit exceeds the threshold voltage. The comparator flips and triggers a monostable multivibrator to output a pulse signal of fixed width. This pulse signal is directly connected to the electromagnet control terminal of the electromagnetic pressure relief valve 15, causing the electromagnetic pressure relief valve 15 to open immediately. The high-pressure fluid is then quickly released back into the water tank 12 through the electromagnetic pressure relief valve 15. This hardware detection circuit does not rely on the software polling of the main control unit 11, and its response time is in the microsecond range, enabling it to quickly suppress water hammer pressure peaks under sudden operating conditions. Simultaneously with the opening of the electromagnetic pressure relief valve 15, the main control unit 11 synchronously outputs a signal to the frequency converter drive unit 10 to reduce the rotational speed. After the pressure returns to the normal range, the electromagnetic pressure relief valve 15 automatically closes, and the system returns to the normal dual-actuator coordinated regulation state.

[0052] Example 5

[0053] The difference between this embodiment and embodiment 1 is that it also includes a reel drive motor 27 to achieve coupled control of the jet reaction force and the nozzle feed speed.

[0054] In this embodiment, the reel drive motor 27 is a hydraulic motor or a servo motor. Its output shaft is connected to the rotating shaft of the reel 13 via a reducer 32. The control terminal of the reel drive motor 27 is connected to the feed control output terminal of the main control unit 11. During normal operation, the main control unit 11 outputs a constant hose reel speed signal to the reel drive motor 27, causing the reel 13 to retract the high-pressure hose 4 at a set speed, driving the nozzle 5 to move at a constant speed within the pipe. When the nozzle 5 sprays a high-pressure jet, it will be subjected to a reaction force opposite to the jet direction. The magnitude of this reaction force is positively correlated with the back pressure value detected by the nozzle back pressure sensor 6 and the flow rate value detected by the flow sensor 9. The main control unit 11 calculates the current jet reaction force based on the signal from the nozzle back pressure sensor 6 and the signal from the flow sensor 9. When nozzle 5 enters the heavily clogged section, the jet flow is obstructed, causing the back pressure to increase and the jet reaction force to increase accordingly. If the original hose reel speed is maintained at this time, nozzle 5 may be unable to advance due to excessive reaction force, causing the high-pressure hose 4 to accumulate, bend, or even knot inside the pipe. The main control unit 11 has a preset jet reaction force threshold. When the calculated jet reaction force exceeds this threshold, the main control unit 11 outputs a signal to the reel drive motor 27 to reduce the speed, slowing down the hose reel 13's reel speed and giving nozzle 5 more time to flush and remove the blockage. When the jet reaction force continues to rise and exceeds a higher secondary threshold, the main control unit 11 outputs a signal to the reel drive motor 27 to stop hose reeling, while simultaneously increasing the output pressure of the high-pressure plunger pump 1 to enhance the flushing capacity. After the blockage is flushed out and the jet reaction force returns to the normal range, the main control unit 11 restores the normal hose reel speed of the reel drive motor 27.

[0055] Example 6

[0056] The difference between this embodiment and embodiment 1 is that it also includes a water tank level sensor 16, an engine load sensor 17, a human-machine interaction touch screen 18, and a wireless communication module 19, and is applied to the entire cleaning vehicle.

[0057] In this embodiment, the vehicle body is modified from a Class II cargo truck chassis. A water tank 12 is installed at the rear of the vehicle body. A high-pressure plunger pump 1 and a drive motor 2 are installed in front of the water tank 12. A reel 13 and a reel drive motor 27 are installed behind the water tank 12. A high-pressure hose 4 is wound around the reel 13. The main control unit 11 and the frequency converter drive unit 10 are installed in the control cabinet on the side of the vehicle body. The human-machine interface touch screen 18 is installed on the operation panel at the rear of the vehicle body. The wireless communication module 19 is installed on the top of the cab. The water tank level sensor 16 is located inside the water tank 12, and the engine load sensor 17 is connected to the vehicle engine ECU. All sensors and actuators are connected to the main control unit 11 via shielded cables or communication buses. The main control unit 11, based on the liquid level signal detected by the water tank level sensor 16, automatically limits the maximum allowable output pressure to a lower level when the liquid level is below the preset lower limit, and reduces the flow rate by reducing the speed of the variable frequency drive unit 10 to prevent cavitation caused by insufficient suction in the high-pressure plunger pump 1. Based on the load signal detected by the engine load sensor 17, it automatically reduces the output pressure or temporarily closes the proportional relief valve 7 to reduce the load when the engine torque percentage exceeds the preset upper limit, and gradually restores the pressure after the engine load recovers. The pressure setting interface of the human-machine interface touch screen 18 allows operators to input the target pressure value or select preset working conditions. The working condition display interface displays the blockage location, working condition type, current pressure and flow data in real time. The parameter configuration interface allows authorized personnel to modify parameters such as the pressure level mapping table 21, wear coefficient, and pressure change threshold. The wireless communication module 19 uploads the operation data, blockage location information, and equipment status to the remote dispatch platform, and receives remote dispatch instructions and parameter configurations.

[0058] Example 7

[0059] The difference between this embodiment and embodiment 1 is that the high-pressure plunger pump 1 adopts a dual-pump parallel redundant configuration.

[0060] In this embodiment, the high-pressure water system includes a first high-pressure plunger pump 1a and a second high-pressure plunger pump 1b. The inlet of the first high-pressure plunger pump 1a is connected to the water tank 12 via a first inlet valve 33a, and the inlet of the second high-pressure plunger pump 1b is connected to the water tank 12 via a second inlet valve 33b. The outlet of the first high-pressure plunger pump 1a is connected to a first outlet branch pipe 34a, and the outlet of the second high-pressure plunger pump 1b is connected to a second outlet branch pipe 34b. A first pump outlet check valve 35a is provided on the first outlet branch pipe 34a, and a second pump outlet check valve 35b is provided on the second outlet branch pipe 34b. The first outlet branch pipe 34a and the second outlet branch pipe 34b are joined together to the outlet pipeline 23 via a connecting joint 30. The output shaft of the first drive motor 2a is connected to the input shaft of the first high-pressure plunger pump 1a, and the output shaft of the second drive motor 2b is connected to the input shaft of the second high-pressure plunger pump 1b. The power output terminal of the first frequency converter drive unit 10a is connected to the power supply terminal of the first drive motor 2a, and the power output terminal of the second frequency converter drive unit 10b is connected to the power supply terminal of the second drive motor 2b. The first pump outlet pressure sensor 3a is installed at the outlet of the first high-pressure plunger pump 1a, and the second pump outlet pressure sensor 3b is installed at the outlet of the second high-pressure plunger pump 1b. The output terminal of the main control unit 11 is connected to the control terminals of the first frequency converter drive unit 10a and the second frequency converter drive unit 10b, respectively, and the input terminal of the main control unit 11 is connected to the signal output terminals of the first pump outlet pressure sensor 3a and the second pump outlet pressure sensor 3b, respectively. Under normal operating conditions, the main control unit 11 only starts the first high-pressure plunger pump 1a to supply water, the second inlet valve 33b is closed, the second high-pressure plunger pump 1b is in standby mode, and the second pump outlet check valve 35b prevents the high-pressure water from the running pump from flowing back into the standby pump; when the operating condition identification submodule 20 determines that there is a severe blockage or that a large-diameter pipeline requires a large flow of high-pressure jet, the main control unit 11 opens the second inlet valve 33b and starts the second variable frequency drive unit 10b, so that the second high-pressure plunger pump 1b and the first high-pressure plunger pump 1a operate in parallel. Both pumps supply water to the outlet pipe 23 through the junction 30. The main control unit 11 adjusts the speed of the first variable frequency drive unit 10a and the second variable frequency drive unit 10b respectively to make the output flow of the two pumps reasonably distributed and the load balanced. When a high-pressure plunger pump or its drive motor fails, the main control unit 11 automatically closes the inlet valve of the faulty pump according to the abnormal signal of the corresponding pump outlet pressure sensor and switches to the other pump to run alone. The one-way valve at the outlet of the faulty pump prevents water from flowing back into the running pump, ensuring that the operation is not interrupted.

[0061] Working principle and usage process of this invention:

[0062] In a typical pipeline maintenance scenario, the operator parks the cleaning truck next to the sewer manhole, places the nozzle 5 into the pipeline, and starts the system. The main control unit 11 receives the operation target setting via the human-machine interface touchscreen 18, or automatically identifies the pipeline condition via the condition identification submodule 20. The pressure wave delay calculation submodule 26 performs cross-correlation calculations using the signal from the nozzle back pressure sensor 6 as a reference and the signal from the pump outlet pressure sensor 3 as the delay signal. Based on the time delay corresponding to the cross-correlation peak, combined with the sound velocity of water, the high-pressure hose 4 discharge length calculated by the reel speed encoder 14, and the fixed length of the outlet pipe 23, the specific location of the blockage point in the pipeline is determined. The phase plane analysis module 29 maps the flow rate and nozzle back pressure signal to the phase plane, and identifies the current condition category through the small-radius limit cycle, non-periodic drift, or large-radius limit cycle morphology of the phase trajectory. The friction loss compensation model module 28 calculates the friction loss based on real-time flow rate, hose extension length, and wear coefficient. The main control unit 11 subtracts the friction loss from the pump outlet pressure to obtain the effective jet pressure of the nozzle as a closed-loop feedback quantity. The pressure level mapping table 21 queries the target pressure value according to the working condition category. Based on the target value, the main control unit 11 simultaneously adjusts the speed of the frequency converter drive unit 10 and the opening of the proportional relief valve 7. During large pressure adjustments, the frequency converter is the main factor, and during fine adjustments, the relief valve is the main factor, achieving adaptive pressure regulation. The reel drive motor 27 automatically adjusts the hose reel speed according to the jet reaction force to prevent the nozzle from jamming.

[0063] In a scenario involving severe pipe blockage, when nozzle 5 approaches the heavily blocked section, the pressure wave delay calculation submodule 26 locates the blockage point in advance, and the phase plane analysis module 29 identifies the phase trajectory as drifting aperiodically towards the high-pressure, low-flow area, thus determining the condition as severe blockage. The main control unit 11 queries the pressure level mapping table 21 to obtain a higher target pressure value, rapidly increasing the speed of the variable frequency drive unit 10 and reducing the opening of the proportional overflow valve 7, causing a rapid increase in output pressure. If the flow rate of a single pump is insufficient, the main control unit 11 starts the second high-pressure plunger pump 1b in parallel operation, with one-way valves at the outlets of both pumps preventing backflow. When the jet reaction force exceeds the threshold, the main control unit 11 slows down the pipe winding speed of the reel drive motor 27, allowing nozzle 5 time to be flushed. The moment the blockage is cleared, the nozzle back pressure drops sharply, and the pressure surge detection circuit immediately triggers the electromagnetic pressure relief valve 15 to briefly open and release excess high pressure, suppressing the water hammer effect. Subsequently, the main control unit 11 readjusts the pressure based on the new condition identification results. The water tank level sensor 16 and the engine load sensor 17 monitor the vehicle status in real time and automatically limit the maximum pressure when resources are limited. The operation data is uploaded to the remote dispatch platform via the wireless communication module 19.

[0064] The improvement of this invention lies in the hardware connection relationship of each module, the signal flow direction and the cooperative working mode. The signal processing operations involved can be implemented by general-purpose digital signal processors or embedded controllers in the prior art, and can be implemented by those skilled in the art based on the description in this specification.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pressure adaptive control system for a high-pressure cleaning vehicle for sewers, characterized in that, It includes a multi-source pressure sensing module, a dual actuator adjustment module and a main control unit (11); the multi-source pressure sensing module includes a pump outlet pressure sensor (3), a nozzle back pressure sensor (6), a return water pressure sensor (8), a flow sensor (9) and a reel speed encoder (14). The pump outlet pressure sensor (3) is located at the outlet of the high-pressure plunger pump (1). The nozzle back pressure sensor (6) is located at the connection between the high-pressure hose (4) and the nozzle (5). The return water pressure sensor (8) is located in the return water branch (22) of the proportional overflow valve (7). The flow sensor (9) is connected in series in the outlet pipe (23). The outlet pipe (23) is also equipped with a filter (24) and a one-way valve (25). The filter (24) is located between the outlet of the high-pressure plunger pump (1) and the flow sensor (9). The reel speed encoder (14) is installed on the shaft of the reel (13). The dual actuator adjustment module includes a frequency converter drive unit (10) and a proportional relief valve (7). The output end of the frequency converter drive unit (10) is connected to the drive motor (2). The output shaft of the drive motor (2) is connected to the input shaft of the high-pressure plunger pump (1) through a coupling (31). The proportional relief valve (7) is connected in series in the return water branch (22). The input terminals of the main control unit (11) are respectively connected to the signal output terminals of the pump outlet pressure sensor (3), the nozzle back pressure sensor (6), the return water pressure sensor (8), the flow sensor (9) and the reel speed encoder (14), and the output terminals of the main control unit (11) are respectively connected to the control terminals of the frequency conversion drive unit (10) and the proportional overflow valve (7). The main control unit (11) is equipped with a pressure wave delay calculation submodule (26). The signal input terminal of the pressure wave delay calculation submodule (26) is connected to the signal output terminal of the pump outlet pressure sensor (3) and the nozzle back pressure sensor (6). The main control unit (11) outputs adjustment signals to the frequency conversion drive unit (10) and the proportional relief valve (7) based on the blockage position signal output by the pressure wave delay calculation submodule (26) and the signal of the multi-source pressure sensing module.

2. The pressure adaptive control system for a high-pressure cleaning truck for sewers according to claim 1, characterized in that: The main control unit (11) is also provided with a working condition identification submodule (20), which includes a phase plane analysis module (29). The signal input terminal of the phase plane analysis module (29) is connected to the signal output terminals of the flow sensor (9) and the nozzle back pressure sensor (6). The identification result output terminal of the phase plane analysis module (29) is connected to the pressure decision input terminal of the main control unit (11).

3. The pressure adaptive control system for a high-pressure cleaning truck for sewers according to claim 1, characterized in that: The main control unit (11) is also provided with a friction loss compensation model module (28). The signal input terminal of the friction loss compensation model module (28) is connected to the signal output terminal of the flow sensor (9) and the reel speed encoder (14). The compensation pressure output terminal of the friction loss compensation model module (28) is connected to the pressure decision input terminal of the main control unit (11).

4. The pressure adaptive control system for a high-pressure cleaning vehicle for sewers according to claim 2, characterized in that: The main control unit (11) also stores a pressure level mapping table (21). The query input end of the pressure level mapping table (21) is connected to the identification result output end of the working condition identification submodule (20). The target pressure output end of the pressure level mapping table (21) is connected to the pressure decision input end of the main control unit (11).

5. The pressure adaptive control system for a high-pressure cleaning truck for sewers according to claim 1, characterized in that: The dual actuator regulating module also includes an electromagnetic pressure relief valve (15), which is connected in parallel to the return water branch (22) at both ends of the proportional overflow valve (7). The main control unit (11) is equipped with a pressure change detection circuit. The signal input terminal of the pressure change detection circuit is connected to the signal output terminals of the pump outlet pressure sensor (3) and the nozzle back pressure sensor (6). The trigger output terminal of the pressure change detection circuit is connected to the control terminal of the electromagnetic pressure relief valve (15).

6. The pressure adaptive control system for a high-pressure cleaning vehicle for sewers according to claim 1, characterized in that: It also includes a reel drive motor (27), the output shaft of which is connected to the rotating shaft of the reel (13) via a reducer (32). The control end of the reel drive motor (27) is connected to the feed control output end of the main control unit (11). The main control unit (11) calculates the jet reaction force based on the signal from the nozzle back pressure sensor (6) and the signal from the flow sensor (9), and outputs a speed adjustment signal to the reel drive motor (27).

7. The pressure adaptive control system for a high-pressure cleaning truck for sewers according to claim 1, characterized in that: It also includes a water tank level sensor (16) and an engine load sensor (17). The water tank level sensor (16) is located inside the water tank (12). The engine load sensor (17) is connected to the ECU output of the vehicle engine. The signal output terminals of the water tank level sensor (16) and the engine load sensor (17) are respectively connected to the input terminal of the main control unit (11).

8. The pressure adaptive control system for a high-pressure cleaning truck for sewers according to claim 1, characterized in that: It also includes a human-machine interaction touch screen (18), which is connected to the main control unit (11) via a communication bus. The human-machine interaction touch screen (18) is provided with a pressure setting interface, a working condition display interface and a parameter configuration interface.

9. The pressure adaptive control system for a high-pressure cleaning truck for sewers according to claim 1, characterized in that: It also includes a wireless communication module (19), which is connected to the communication port of the main control unit (11) and interacts with the remote scheduling platform.

10. The pressure adaptive control system for a high-pressure cleaning vehicle for sewers according to claim 1, characterized in that: The high-pressure plunger pump (1) is a dual-pump parallel configuration, including a first high-pressure plunger pump (1a) and a second high-pressure plunger pump (1b). The inlet of each high-pressure plunger pump is connected to a water tank (12) via a first inlet valve (33a) and a second inlet valve (33b). The outlet of each high-pressure plunger pump is connected to a junction connector (30) via a first outlet branch pipe (34a) and a second outlet branch pipe (34b). A first pump outlet check valve (35a) is provided on the first outlet branch pipe (34a), and a second pump outlet check valve (35b) is provided on the second outlet branch pipe (34b). The junction connector (30) is connected to the outlet pipeline (23). Each high-pressure plunger pump is equipped with an independent first drive motor (2a), a second drive motor (2b), a first variable frequency drive unit (10a), and a second variable frequency drive unit (10b). Each high-pressure plunger pump is equipped with a first pump outlet pressure sensor (3a) and a second pump outlet pressure sensor (3b) at its outlet. The output of the main control unit (11) is connected to the control terminals of the first variable frequency drive unit (10a) and the second variable frequency drive unit (10b), respectively. The input of the main control unit (11) is connected to the signal output terminals of the first pump outlet pressure sensor (3a) and the second pump outlet pressure sensor (3b), respectively.

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