A paver and a paving control method

Abstract

This invention discloses a paver and a paving control method. The paver includes a main unit, a screed, a boom, a lifting cylinder, a state switching valve, and a paving controller. When the paver switches from a paving stop state to a normal paving state, the paving controller controls the state switching valve to ensure that both the lifting and lowering chambers of the lifting cylinder are in a pressure-free state. After a set time period, the paving controller controls the state switching valve to either lock the lowering chamber of the lifting cylinder, depressurize the lifting chamber, or lock the cylinder, and then controls the paver to begin paving. After a set time period, the paving controller controls the state switching valve to ensure that both the lifting and lowering chambers of the lifting cylinder are in a pressure-free state. This paving control method helps to avoid road surface slab formation during start-up, ensuring the quality of road construction.

Description

Technical Field

[0001] This invention relates to a paver and a paving control method, belonging to the field of road construction machinery technology. Background Technology

[0002] A paver is a specialized construction equipment used to pave base stabilized materials and surface asphalt mixtures for various grades of highways and municipal roads. It has a significant impact on the quality of road construction. A paver consists of a main unit, a screed, and a boom, and in most cases, an automatic leveling system. The main unit provides power and pulls the screed forward. The boom is hinged to the main unit and connected to the screed behind it. The screed is used to initially compact, smooth, and ultimately shape the pavement material. The main unit generally also includes leveling cylinders and lifting cylinders. The leveling cylinders adjust the height of the hinge point between the boom and the main unit, while the lifting cylinders raise or lower the screed.

[0003] Pavers typically employ a floating paving principle, meaning that under normal paving conditions, the two chambers of the lifting cylinder are connected and in a pressure-free state (meaning there is no pressure difference relative to atmospheric pressure). The screed remains in equilibrium under its own weight, traction force, and material forces. The automatic leveling system includes leveling sensors and a leveling controller. The leveling sensors detect the height deviation of the screed relative to a leveling reference point. The leveling controller receives the height deviation signal detected by the leveling sensors and controls the leveling cylinders to ultimately control the height of the screed, thereby ensuring paving thickness and smoothness.

[0004] As is well known to those skilled in the art, during paving, when the paver is in a stopped state (forward speed is 0 but the paver still has control functions) due to waiting for material trucks, the road surface is prone to stop marks, which affect the final quality of the road surface. The most common solution currently used in the industry is to lock the lifting chamber of the lifting cylinder when paving is stopped, but this still cannot completely eliminate the stop mark phenomenon.

[0005] Chinese invention patent CN202110858811.5 proposes a method to reduce stop marks by applying pressure to the lifting chamber of the lifting cylinder when the paver is in a stopped state. Further research revealed that while this method effectively eliminates stop marks, applying pressure to the lifting chamber of the lifting cylinder during a stopped state causes a change in the paver's posture. This change in posture may lead to a slab-like phenomenon when the paver restarts paving, which is detrimental to the final road surface quality. Summary of the Invention

[0006] The purpose of this invention is to provide a paver and a paving control method. When the paver switches to the normal paving state, the state of the lifting chamber and the lowering chamber of the lifting cylinder are changed by the state switching valve to avoid the phenomenon of starting up and lifting the platform, which is conducive to improving the final road surface quality.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a paver, including a main unit, a screed, a boom, and a lifting cylinder, and also includes a state switching valve and a paving controller;

[0009] The state switching valve is used to change the state of the lifting chamber and the lowering chamber of the lifting cylinder;

[0010] The paving controller is used to control the energization of the state switching valve and to control the paver to perform paving.

[0011] The paving controller is specifically used for,

[0012] When the paver switches from normal paving state to paving stop state, the control state switching valve keeps the lifting chamber of the lifting cylinder in a locked state or a pressurized state, and keeps the lowering chamber in a depressurized state.

[0013] When switching from the paving stop state to the normal paving state, the control state switching valve keeps both the lifting chamber and the lowering chamber of the lifting cylinder in a pressure-free state.

[0014] After a set time period, the control state switching valve puts the lowering chamber of the lifting cylinder into a locked state, and the lifting chamber into a pressureless state or a locked state, and controls the paver to start paving.

[0015] After a set time of two, the control state switching valve puts both the lifting chamber and the lowering chamber of the lifting cylinder into a pressure-free state.

[0016] Furthermore, the set time is a preset value.

[0017] Furthermore, the set time two is negatively correlated with the paving speed.

[0018] Furthermore, the second set time is positively correlated with the time the paver is in the paving stop state.

[0019] Furthermore, the paver also includes an ambient temperature sensor;

[0020] The ambient temperature sensor includes an air temperature sensor and a roadbed temperature sensor.

[0021] Furthermore, the set time two is negatively correlated with the ambient temperature; the ambient temperature is the weighted average of the air temperature value detected by the air temperature sensor and the roadbed temperature detected by the roadbed temperature sensor.

[0022] Furthermore, the state switching valve includes state switching valve one and state switching valve two;

[0023] The two inlets of the state switching valve are connected to the return oil tank, and the two outlets are connected to the lifting chamber and the lowering chamber of the two lifting cylinders, respectively.

[0024] The two inlets of the state switching valve 2 are connected to the pressure oil and the return oil tank, respectively, and the outlet is connected to the lifting chamber of the two lifting cylinders.

[0025] The paver also includes an electrically adjustable booster valve, which is connected between the state switching valve and the lifting chamber of the lifting cylinder. The electrically adjustable booster valve is used to adjust the pressure of the lifting chamber of the lifting cylinder when the paving is stopped.

[0026] Furthermore, the set time is positively correlated with the pressure of the electrically regulated booster valve.

[0027] The present invention also provides a paving control method, comprising:

[0028] Get the paver status.

[0029] When the paver switches from normal paving state to paving stop state, the control state switching valve keeps the lifting chamber of the lifting cylinder in a locked state or a pressurized state, and keeps the lowering chamber in a depressurized state.

[0030] If the paver switches from the paving stop state to the normal paving state, the lifting chamber and the lowering chamber of the lifting cylinder are both in a pressure-free state by controlling the opening and closing of the state switching valve.

[0031] After a set time, the control state switching valve puts the lowering chamber of the lifting cylinder into a locked state, and the lifting chamber into a pressureless state or a locked state, and controls the paver to start paving.

[0032] After a set time of two, the control state switching valve puts both the lifting chamber and the lowering chamber of the lifting cylinder into a pressure-free state.

[0033] Furthermore, if the paver is in a paving stop state, the control state switching valve keeps the lifting chamber of the lifting cylinder pressurized and the lowering chamber depressurized.

[0034] The beneficial effects of this invention are as follows:

[0035] This invention provides a paver that uses a state switching valve to change the state of the lifting and lowering chambers of the lifting cylinder. When the paver switches from a paving stop state to a normal paving state, the state switching valve is first controlled to ensure that both the lifting and lowering chambers of the lifting cylinder are in a pressure-free state. After a set time period, the main unit has returned to its normal paving posture. At this point, the lowering chamber of the lifting cylinder is locked, the lifting chamber is in a pressure-free state, or the paver is controlled to start paving, effectively preventing the screed from lifting during startup. After another set time period, the screed has passed the cold material area, and the paving controller controls the state switching valve to ensure that both the lifting and lowering chambers of the lifting cylinder are in a pressure-free state, allowing the screed to enter a normal floating paving state. When the paver is in a paving stop state, the state switching valve is controlled to ensure that the lifting and lowering chambers of the lifting cylinder are in a pressurized state and a pressure-free state, respectively, which also effectively prevents the occurrence of indentations during shutdown. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the paver provided by the present invention;

[0037] Figure 2 The hydraulic principle diagram of the paver provided by this invention. Detailed Implementation

[0038] The present invention will now be further described. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0039] This invention provides a paver, see below. Figure 1 The system includes a main unit 1, a screed 2, a boom 3, a lifting cylinder 4, a state switching valve, and a paving controller 8. The main unit provides power and pulls the screed forward. The boom is hinged to the main unit and connected to the screed behind it. The screed is used to initially compact, smooth, and ultimately shape the pavement material. The lifting cylinder is hinged to the main unit and connected to the rear of the boom to adjust the height of the screed. The state switching valve is used to change the state of the lifting chamber and the lowering chamber of the lifting cylinder. The paving controller is used to control the state switching valve and the paving function of the paver.

[0040] In this invention, the paving controller is specifically used for,

[0041] When the paving is stopped, the control state switching valve keeps the lifting chamber of the lifting cylinder pressurized and the lowering chamber depressurized, which can better avoid the phenomenon of indentation during machine stop.

[0042] When switching from the paving stop state to the normal paving state, the control state switching valve keeps both the lifting chamber and the lowering chamber of the lifting cylinder in a pressure-free state.

[0043] After a set time period, the control state switching valve puts the lowering chamber of the lifting cylinder into a locked state, and the lifting chamber into a pressureless state or a locked state, and controls the paver to start paving.

[0044] After a set time of two, the control state switching valve puts both the lifting chamber and the lowering chamber of the lifting cylinder into a pressure-free state.

[0045] It should be noted that in this invention, the state switching valve can be a single hydraulic valve or a combination of multiple hydraulic valves.

[0046] It should be noted that in this invention, the paving controller can be an additional controller, but it is best to use the existing controller on the paver so as not to increase any cost.

[0047] It should be noted that the lifting cylinder is typically connected to the main unit on one side of the cylinder barrel and to the boom on the other side of the piston rod. In this case, the lower chamber of the cylinder is the lifting chamber and the upper chamber is the lowering chamber. This common configuration is also used in this invention. However, theoretically, it is also feasible to configure it in the opposite way.

[0048] It should be noted that when one of the lifting chamber and the lowering chamber of the lifting cylinder is in a locked state and the other is in a pressurized state, it can be considered as a two-chamber locked state.

[0049] It should be noted that when the paver moves from the normal paving state to the paving stop state, regardless of whether the paver uses a technology where the lifting cylinder lifting chamber is in a locked state, or a technology where the lifting cylinder lifting chamber and lowering chamber are in a pressurized state and a pressureless state respectively, the posture of the main unit will change to some extent.

[0050] It should be noted that the controller of current pavers usually has a timing function, so there is usually no need to set a separate timer to keep track of the paving stop time, set time one, and set time two.

[0051] In this invention, the set time can be a fixed value, such as 2s or 3s. Under normal circumstances, this time interval is sufficient for the host attitude to fully recover.

[0052] When the paver is stopped and waiting for material trucks for an extended period, the asphalt mixture cools and hardens. Upon restarting paving, this can cause the screed to lift, resulting in a lifting screed. In this situation, locking the lowering chamber of the lifting cylinder helps prevent or mitigate screed lifting. After a set time has elapsed, once the screed has passed the cold material zone, the lifting and lowering chambers of the lifting cylinder are depressurized, restoring normal floating paving.

[0053] The faster the paving speed, the shorter the time required for the screed to pass through the cold material zone. Therefore, the time setting can be negatively correlated with the paving speed, for example, inversely proportional.

[0054] The longer the paver remains in the paving stop state, the more the asphalt mixture cools down. Therefore, it is best to set the timer for the paver to be longer to avoid the paver starting up.

[0055] The degree of cooling of asphalt mixture is related not only to the paving stop time but also to the ambient temperature. The lower the ambient temperature, the more the asphalt mixture cools in the same amount of time, and in this case, the set time should ideally be longer. The ambient temperature can specifically include air temperature and subgrade temperature. The lower the air temperature or subgrade temperature, the more the asphalt mixture cools in the same amount of time, and the longer the set time should ideally be.

[0056] In one embodiment of the present invention, an ambient temperature sensor 7 is installed on the paver, specifically including an air temperature sensor and a roadbed temperature sensor, for detecting air temperature and roadbed temperature values. A negative correlation between the set time and the ambient temperature helps to eliminate or mitigate the starting and slab-raising phenomenon. The ambient temperature value is the weighted average of the air temperature value detected by the air temperature sensor and the roadbed temperature value detected by the roadbed temperature sensor. The ambient temperature sensor 7 can be installed on the main unit, the screed, or other suitable locations for detecting air temperature or roadbed temperature values.

[0057] See Figure 2 In one embodiment of the present invention, there are two lifting cylinders and two state switching valves. State switching valve one 51 is a three-position four-way solenoid directional valve, and state switching valve two 52 is a two-position three-way solenoid directional valve. The two inlets of state switching valve one 51 are connected to port T (i.e., connected to the return oil tank), and the two outlets are respectively connected to the lifting chamber and lowering chamber of the two lifting cylinders. The two inlets of state switching valve two 52 are respectively connected to port P (pressure oil) and port T, and the outlet is connected to the lifting chamber of the two lifting cylinders.

[0058] In addition, it also includes an electrically adjustable booster valve 6, which is connected between the state switching valve 2 52 and the lifting chamber of the lifting cylinder. The electrically adjustable booster valve 6 is used to adjust the pressure of the lifting chamber of the lifting cylinder when the paving is stopped.

[0059] The paving control method based on this structure is as follows:

[0060] During normal paving, the paving controller 8 controls the state switching valve 1 51 and state switching valve 2 52 to be de-energized, so that the lifting chamber and lowering chamber of the two lifting cylinders 4 are connected to the T port (i.e. connected to the return oil tank) and are in a pressure-free state. At this time, the electric regulating assist valve 6 does not work.

[0061] When paving is stopped, the paving controller 8 energizes both the upper position of the first state switching valve 51 and the second state switching valve 52, causing the lowering chambers (upper chambers) of both lifting cylinders 4 to be connected to the T port in a pressureless state. The P port (pressure oil) is connected to the lifting chambers (lower chambers) of the two lifting cylinders 4 via the second state switching valve 52 and the electric regulating valve 6, causing the lifting chambers to be pressurized. It should be noted that in this embodiment, the upper and lower positions of the first state switching valve 51 refer to... Figure 2 The upper and lower positions of the state switching valve 51 are shown.

[0062] When the paver switches from the paving stop state to the normal paving state, the paving controller 8 controls the state switching valve 1 51 and the state switching valve 2 52 to be de-energized, so that the lifting chamber and lowering chamber of the two lifting cylinders 4 are connected to the T port (i.e. connected to the return oil tank) and are in a pressure-free state.

[0063] After a set time period, the paving controller 8 controls the lower position of the state switching valve 1 51 to be energized and the lower position of the state switching valve 2 52 to be de-energized, so that the lifting chambers (lower chambers) of the two lifting cylinders 4 are connected to the T port and are in a pressureless state, and the lowering chambers (upper chambers) of the two lifting cylinders 4 are in a locked (non-connected) state.

[0064] After a set time of two, the paving controller 8 de-energizes both the first state switching valve 51 and the second state switching valve 52, so that the lifting chamber and lowering chamber of the two lifting cylinders 4 are connected to the T port (i.e., connected to the return oil tank) and are in a pressure-free state.

[0065] It should be noted that the preferred electrically adjustable booster valve is an electro-proportional pressure reducing valve, which allows direct adjustment of the valve's outlet pressure, i.e., the pressure in the lifting chamber of the booster cylinder, via current. This approach is relatively simple to implement. Alternatively, adjusting the pressure in the lifting chamber of the booster cylinder using an electro-proportional relief valve or other hydraulic valves is also feasible.

[0066] It should be noted that the electrically adjustable booster valve can be a fixed pressure valve, a manually adjustable pressure valve, or an electrically adjustable pressure valve.

[0067] It should be noted that the set time can also be positively correlated with the pressure of the electric regulating valve, for example, it can be linearly correlated or proportional. For instance, when the pressure of the electric regulating valve reaches its maximum value, the set time also reaches its maximum value of 3 seconds. When the pressure of the electric regulating valve is a certain proportion of its maximum value, the set time is also a certain proportion of 3 seconds. The higher the pressure of the electric regulating valve, the greater the change in the paver's attitude when switching from the paving stop state to the normal paving state, thus requiring a longer recovery time.

[0068] The paving control method based on the above-mentioned paver is as follows:

[0069] Get the paver status.

[0070] If the paver is in normal paving mode, the lifting chamber and lowering chamber of the lifting cylinder are kept in a pressure-free state by controlling the opening and closing of the state switching valve.

[0071] If the paver is in the paving stop state, the lifting chamber of the lifting cylinder is controlled to be in a pressurized state and the lowering chamber is in a depressurized state by controlling the opening and closing of the state switching valve.

[0072] If the paver switches from the paving stop state to the normal paving state, the lifting chamber and the lowering chamber of the lifting cylinder are both in a pressure-free state by controlling the opening and closing of the state switching valve.

[0073] After a set time period, the control state switching valve puts the lowering chamber of the lifting cylinder into a locked state, and the lifting chamber into a pressureless state or a locked state, and controls the paver to start paving.

[0074] After a set time of two, the control state switching valve puts both the lifting chamber and the lowering chamber of the lifting cylinder into a pressure-free state.

[0075] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A paver, comprising a main unit, a screed, a boom, and a lifting cylinder, characterized in that, It also includes state switching valves and paving controllers; The state switching valve is used to change the state of the lifting chamber and the lowering chamber of the lifting cylinder; The paving controller is used to control the energization of the state switching valve and to control the paver to perform paving. The paving controller is specifically used for, When the paver switches from normal paving state to paving stop state, the control state switching valve keeps the lifting chamber of the lifting cylinder in a locked state or a pressurized state, and keeps the lowering chamber in a depressurized state. When switching from the paving stop state to the normal paving state, the control state switching valve keeps both the lifting chamber and the lowering chamber of the lifting cylinder in a pressure-free state. After a set time period, the control state switching valve puts the lowering chamber of the lifting cylinder into a locked state, and the lifting chamber into a pressureless state or a locked state, and controls the paver to start paving. After a set time of two, the control state switching valve puts both the lifting chamber and the lowering chamber of the lifting cylinder into a pressure-free state.

2. A paver according to claim 1, characterized in that, The set time is a preset value.

3. A paver according to claim 1, characterized in that, The set time 2 is negatively correlated with the paving speed.

4. A paver according to claim 1, characterized in that, The second set time is positively correlated with the time the paver is in the paving stop state.

5. A paver according to claim 1, characterized in that, The paver also includes an ambient temperature sensor; The ambient temperature sensor includes an air temperature sensor and a roadbed temperature sensor.

6. A paver according to claim 5, characterized in that, The set time 2 is negatively correlated with the ambient temperature; the ambient temperature is the weighted average of the air temperature value detected by the air temperature sensor and the roadbed temperature detected by the roadbed temperature sensor.

7. A paver according to any one of claims 1 to 6, characterized in that, The state switching valve includes state switching valve one and state switching valve two; The two inlets of the state switching valve are connected to the return oil tank, and the two outlets are connected to the lifting chamber and the lowering chamber of the two lifting cylinders, respectively. The two inlets of the state switching valve 2 are connected to the pressure oil and the return oil tank, respectively, and the outlet is connected to the lifting chamber of the two lifting cylinders. The paver also includes an electrically adjustable booster valve, which is connected between the state switching valve and the lifting chamber of the lifting cylinder. The electrically adjustable booster valve is used to adjust the pressure of the lifting chamber of the lifting cylinder when the paving is stopped.

8. A paver according to claim 7, characterized in that, The set time is positively correlated with the pressure of the electrically adjustable booster valve.

9. The paving control method for the paver according to any one of claims 1 to 8, characterized in that, include: Get the paver status. When the paver switches from normal paving state to paving stop state, the control state switching valve keeps the lifting chamber of the lifting cylinder in a locked state or a pressurized state, and keeps the lowering chamber in a depressurized state. If the paver switches from the paving stop state to the normal paving state, the lifting chamber and the lowering chamber of the lifting cylinder are both in a pressure-free state by controlling the opening and closing of the state switching valve. After a set time, the control state switching valve puts the lowering chamber of the lifting cylinder into a locked state, and the lifting chamber into a pressureless state or a locked state, and controls the paver to start paving. After a set time of two, the control state switching valve puts both the lifting chamber and the lowering chamber of the lifting cylinder into a pressure-free state.

10. The paving control method for a paver according to claim 9, characterized in that, If the paver is in a paving stop state, the control state switching valve keeps the lifting chamber of the lifting cylinder pressurized and the lowering chamber depressurized.

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