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, an electrically adjustable loading valve, and a paving controller. When the paver switches from a paving stop state to a normal paving state, the paving controller first controls the state switching valve to put the lifting chamber and lowering chamber of the lifting cylinder into a pressureless state and a pressurized state, respectively, and then controls the electrically adjustable loading valve to adjust the pressure in the lowering chamber of the lifting cylinder. After a set time, the paving controller controls the state switching valve to put both the lifting chamber and lowering chamber of the lifting cylinder into a pressureless state. The paving method of this invention helps to avoid road surface indentations caused by stopping and platform erection upon starting, 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] During paving, when the paver is stopped due to waiting for material trucks, the lifting chamber of the lifting cylinder is usually locked or pressurized to prevent indentations caused by the machine stopping. While the paver is stopped waiting for material trucks, the asphalt mixture gradually cools and hardens. When the paver switches from the stopped state to normal paving, the screed is easily lifted by the cooled and hardened asphalt mixture, resulting in a lifting effect, which is detrimental to the final road surface quality.

[0005] The most common solution to the initial stage lifting phenomenon is to lock the lowering chamber of the lifting cylinder for several seconds when the paver switches from a stopped paving state to a normal paving state. However, further research has found that this solution cannot completely eliminate the initial stage lifting phenomenon, and there is still room for improvement in the existing technology. Summary of the Invention

[0006] The purpose of this invention is to provide a paver and a paving control method that can avoid the phenomenon of starting up and lifting when the paver switches to normal paving mode, which is beneficial to improving the final quality of the road surface.

[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, an electrically adjustable loading 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; the state includes a pressurized state and a pressureless state.

[0010] The electrically adjustable loading valve is used to adjust the pressure in the lowering chamber of the lifting cylinder;

[0011] The paving controller is used to control the on / off state switching valve and the electrically adjustable loading valve;

[0012] The paving controller is specifically used for,

[0013] When the paver switches from the paving stop state to the normal paving state, the control state switching valve makes the lifting chamber of the lifting cylinder unpressurized and the lowering chamber pressurized, and at least based on the paving stop time, the control electric regulating loading valve adjusts the pressure of the lowering chamber of the lifting cylinder.

[0014] After a set time, the control state switching valve puts both the lifting and lowering chambers of the lifting cylinder into a pressure-free state.

[0015] Furthermore, when the paver switches from the paving stop state to the normal paving state, the pressure in the lowering chamber of the lifting cylinder is linearly positively correlated with the paving stop time.

[0016] Furthermore, the paver also includes an ambient temperature sensor;

[0017] When the paver switches from a stopped paving state to a normal paving state, the paving controller is also used for:

[0018] The electrically adjustable loading valve is controlled based on the ambient temperature detected by the ambient temperature sensor.

[0019] Furthermore, the ambient temperature sensor includes an air temperature sensor and a roadbed temperature sensor;

[0020] 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.

[0021] Furthermore, the paving controller is used to, when the paver switches from a paving stop state to a normal paving state, perform the following actions:

[0022] The electrically adjustable loading valve is controlled in such a way that the pressure in the lowering chamber of the lifting cylinder is linearly negatively correlated with the ambient temperature.

[0023] Furthermore, the set time is a fixed value.

[0024] Furthermore, the set time is negatively correlated with the paving speed.

[0025] Furthermore, the set time is negatively correlated with the ambient temperature.

[0026] Furthermore, the state switching valve includes state switching valve one, state switching valve two, and state switching valve three; the paver also includes an electric regulating assist valve;

[0027] 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.

[0028] The two inlets of the state switching valve are connected to the pressure oil and the return oil tank, respectively, and the outlet is connected to the inlet of the electrically adjustable loading valve. The outlet of the electrically adjustable loading valve is connected to the lowering chamber of the two lifting cylinders.

[0029] The two inlets of the state switching valve three are connected to the pressure oil and the return oil tank, respectively, and the outlet is connected to the inlet of the electrically adjustable booster valve. The outlet of the electrically adjustable loading valve is connected to the lifting chamber of the two lifting cylinders.

[0030] The electrically adjustable booster valve is used to adjust the pressure in the lifting chamber of the lifting cylinder when paving is stopped.

[0031] This invention also provides a paving control method, including:

[0032] Get the paver status.

[0033] If the paver switches from the paving stop state to the normal paving state, the lifting chamber of the lifting cylinder is controlled to be in a pressureless state and the lowering chamber is in a pressurized state by controlling the opening and closing of the state switching valve. The pressure of the lowering chamber of the lifting cylinder is adjusted by the electric regulating loading valve based on the paving stop time.

[0034] After a set time, the control state switching valve ensures that both the lifting and lowering chambers of the lifting cylinder are in a pressure-free state.

[0035] The beneficial effects of this invention are as follows:

[0036] When the paver switches from the paving stop state to the normal paving state, the paving controller first controls the state switching valve to put the lifting chamber and lowering chamber of the lifting cylinder into a pressureless state and a pressured state, respectively. The paving controller also controls the electric regulating loading valve based on the paving stop time to control the pressure of the lowering chamber of the lifting cylinder to prevent the screed from lifting and causing the platform to rise. After a set time, the paving controller controls the state switching valve to put both the lifting chamber and lowering chamber of the lifting cylinder into a pressureless state, and the screed enters the normal floating paving state.

[0037] Furthermore, when the paver is in a stopped state, the paving controller controls the state switching valve to keep the lifting chamber and lowering chamber of the lifting cylinder in a pressurized state and a pressureless state, respectively. This can effectively prevent the occurrence of indentations during machine stoppage. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the paver provided by the present invention;

[0039] Figure 2 This is a schematic diagram of the hydraulic principle in the paver provided by the present invention.

[0040] 1-Main unit, 2-Screed, 3-Boom, 4-Lifting cylinder, 51-State switching valve one, 52-State switching valve two, 53-State switching valve three, 6-Electrically adjustable loading valve, 7-Ambient temperature sensor, 8-Paving controller, 9-Electrically adjustable assist valve. Detailed Implementation

[0041] 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.

[0042] 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, an electrically adjustable loading 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 electrically adjustable loading valve is used to adjust the pressure of the lowering chamber of the lifting cylinder. The paving controller is used to control the state switching valve and the electrically adjustable loading valve.

[0043] The paving controller is specifically used for,

[0044] When the paver is in the paving stop state, the control state switching valve keeps the lifting chamber of the lifting cylinder pressurized and the lowering chamber depressurized, which can prevent the paver from having stoppage indentations.

[0045] When the paver switches from the paving stop state to the normal paving state, the control state switching valve makes the lifting chamber of the lifting cylinder unpressurized and the lowering chamber pressurized. The electric regulating loading valve is controlled based on the paving stop time to adjust the pressure of the lowering chamber of the lifting cylinder.

[0046] After a set time, the control state switching valve ensures that both the lifting and lowering chambers of the lifting cylinder are in a pressure-free state.

[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 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 and the set time.

[0049] In this invention, the set time can be a fixed value, such as 5s or 10s. After this fixed time, the screed has usually passed the cold material zone, so it can return to the normal spreading state.

[0050] The faster the paving speed, the shorter the time required for the screed to pass through the cold material zone. Therefore, the setting time can also be negatively correlated with the paving speed, for example, inversely proportional.

[0051] The longer the paver remains in the paving stop state, the more the asphalt mixture cools down. Therefore, it is best to set a longer time in this case to avoid the paver starting up again.

[0052] When the paver is in the paving stop time state, the lower the ambient temperature, the more the asphalt mixture cools down, and the longer the set time should be.

[0053] In this invention, the electrically adjustable loading valve functions to regulate the pressure in the lowering chamber of the lifting cylinder. Preferably, the electrically adjustable loading valve is an electro-proportional constant-value pressure reducing valve, which allows direct adjustment of the outlet pressure of the constant-value pressure reducing valve, i.e., the pressure in the lowering chamber of the lifting cylinder, via current. This approach is relatively simple to implement. Regulating the pressure in the lowering chamber of the lifting cylinder using an electro-proportional relief valve or other hydraulic valves is also feasible.

[0054] The longer the paver waits for material trucks while paving is stopped, the colder and harder the asphalt mixture becomes. This makes it easier to lift the screed when restarting paving, resulting in a platform lifting phenomenon. Therefore, it is necessary to control the electrically adjustable loading valve based on the paving stop time to regulate the pressure in the lowering chamber of the lifting cylinder. The longer the paving stop time, the greater the pressure required in the lowering chamber of the lifting cylinder.

[0055] The pressure in the lowering chamber of the lifting cylinder can be linearly positively correlated with the paving stop time. For example, when the paving stop time is less than 1 minute, the pressure in the lowering chamber of the lifting cylinder is set to 1 MPa; when the paving stop time reaches 30 minutes, the pressure is set to 5 MPa; and when the paving stop time is between 1 minute and 30 minutes, the pressure setting ranges from 1 MPa to 5 MPa and is linearly positively correlated with the paving stop time. It is conceivable that the pressure in the lowering chamber of the lifting cylinder may also have other positively correlated relationships with the paving stop time.

[0056] When the paver is in a stopped state waiting for the material truck, the degree of cooling and hardening of the asphalt mixture is also related to the ambient temperature. The lower the ambient temperature, the easier it is for the asphalt mixture to cool and harden. Therefore, the pressure of the lifting cylinder's lowering chamber should ideally be negatively correlated with the ambient temperature.

[0057] The ambient temperature that affects the degree of cooling and hardening of asphalt mixture mainly includes air temperature and subgrade temperature. Therefore, as a preferred embodiment of the present invention, an ambient temperature sensor 7 is installed on the paver. The ambient temperature sensor 7 includes an air temperature sensor and a subgrade temperature sensor. The ambient temperature value is the weighted average of the air temperature value detected by the air temperature sensor and the subgrade temperature value detected by the subgrade temperature sensor. For example, the ambient temperature value can simply be the average of the air temperature value and the subgrade temperature value.

[0058] It should be noted that the pressure in the lowering chamber of the lifting cylinder can be set to be linearly negatively correlated with the ambient temperature, or other negatively correlated relationships are also possible.

[0059] 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.

[0060] 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.

[0061] See Figure 2 In one embodiment of the present invention, there are two lifting cylinders and three state switching valves, namely state switching valve one 51, state switching valve two 52 and state switching valve three 53; it also includes an electric regulating assist valve 9, which is used to adjust the pressure of the lifting chamber of the lifting cylinder in the paving stop state.

[0062] Among them, state switching valve 1 51 is a three-position four-way solenoid directional valve, state switching valve 2 52 and state switching valve 3 53 are both two-position three-way solenoid directional valves, and electric regulating loading valve 6 and electric regulating assist valve 9 are electric proportional setpoint pressure reducing valves.

[0063] State switching valve 1 (51) has two inlets connected to port T (i.e., connected to the return oil tank), and two outlets connected to the lifting and lowering chambers of the two lifting cylinders, respectively. State switching valve 2 (52) has two inlets connected to port P (pressure oil) and port T, respectively, and its outlet connected to the inlet of electrically adjustable loading valve 6. The outlet of electrically adjustable loading valve 6 is connected to the lowering chamber of the two lifting cylinders. State switching valve 3 (53) has two inlets connected to port P (pressure oil) and port T, respectively, and its outlet connected to the inlet of electrically adjustable booster valve 9. The outlet of electrically adjustable loading valve 9 is connected to the lifting chamber of the two lifting cylinders.

[0064] The paving control method based on this structure is as follows:

[0065] During normal paving, the paving controller 8 controls the state switching valves 1 (51), 2 (52), and 3 (53) to be de-energized. The lifting and lowering chambers 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 loading valve 6 and the electric regulating assist valve 9 are not functional.

[0066] When paving is stopped, the paving controller 8 controls the upper position of the state switching valve 1 51 and the state switching valve 3 53 to be energized, while the state switching valve 2 52 is not energized. At this time, the lowering chamber (upper chamber) of the two lifting cylinders 4 is connected to the T port and is in a pressureless state. The P port (pressure oil) is connected to the lifting chamber (lower chamber) of the two lifting cylinders 4 through the state switching valve 3 53 and the electric regulating assist valve 9, so that the lifting chamber is in a pressure state.

[0067] When the paver switches from the paving stop state to the normal paving state, the paving controller 8 first controls the lower position of the state switching valve 1 51 and the state switching valve 2 52 to be energized. The lifting chambers (lower chambers) of the two lifting cylinders 4 are connected to the T port (i.e., connected to the return oil tank) and are in a pressureless state. The P port (pressure oil) is connected to the lowering chambers (upper chambers) of the two lifting cylinders 4 through the state switching valve 2 52 and the electric regulating loading valve 6, so that the lowering chambers are in a pressurized state.

[0068] After a set time, the paving controller 8 once again controls the state switching valve 1 51, state switching valve 2 52 and state switching valve 3 53 to de-energize, and 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.

[0069] 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.

[0070] Electrically adjustable booster valves can be fixed pressure, manually adjustable pressure, or electrically adjustable pressure.

[0071] The paving control method based on the above-mentioned paver is as follows:

[0072] Get the paver status.

[0073] 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.

[0074] If the paver switches from the paving stop state to the normal paving state, the lifting chamber of the lifting cylinder is controlled to be in a pressureless state and the lowering chamber is in a pressurized state by controlling the opening and closing of the state switching valve. The pressure of the lowering chamber of the lifting cylinder is adjusted by the electric regulating loading valve based on the paving stop time.

[0075] After a set time, the control state switching valve ensures that both the lifting and lowering chambers of the lifting cylinder are in a pressure-free state.

[0076] 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 paving machine comprising a main machine, a screed, a boom and a lift cylinder, characterized in that, The state switching valve, the electrically regulated loading valve and the paving controller are further included; The state switching valve is used to change the state of the lifting cylinder lifting chamber and the lowering chamber; the state includes a pressure state and a pressure-free state; The electrically regulated loading valve is used to regulate the pressure of the lifting cylinder lowering chamber; The paving controller is used to control the on-off of the state switching valve and the electrically regulated loading valve; The paving controller is specifically used to, When the paver is switched from the paving stop state to the normal paving state, the state switching valve is controlled to make the lifting chamber of the lifting cylinder in the pressure-free state and the lowering chamber in the pressure state, and the electrically regulated loading valve is controlled to regulate the pressure of the lifting cylinder lowering chamber based on at least the paving stop time; After a set time, the state switching valve is controlled to make the lifting chamber and the lowering chamber of the lifting cylinder both in the pressure-free state.

2. A paving machine according to claim 1, characterized in that When the paver is switched from the paving stop state to the normal paving state, the pressure of the lifting cylinder lowering chamber is linearly and positively related to the paving stop time.

3. A paving machine according to claim 1, wherein The paver further includes an ambient temperature sensor; When the paver is switched from the paving stop state to the normal paving state, the paving controller is further used to, Control the electrically regulated loading valve based on the ambient temperature detected by the ambient temperature sensor.

4. A paving machine according to claim 3, wherein The ambient temperature sensor includes an air temperature sensor and a roadbed temperature sensor; The ambient temperature is a weighted average of the air temperature detected by the air temperature sensor and the roadbed temperature detected by the roadbed temperature sensor.

5. A paving machine according to claim 4, wherein The paving controller is used to, when the paver is switched from the paving stop state to the normal paving state, Control the electrically regulated loading valve in a manner that makes the pressure of the lifting cylinder lowering chamber linearly and negatively related to the ambient temperature.

6. A paving machine as claimed in claim 1, characterized in that The set time is a fixed value.

7. A paving machine as claimed in claim 1, wherein The set time is negatively related to the paving speed.

8. A paving machine according to claim 4 wherein, The set time is negatively related to the ambient temperature.

9. A paving machine as claimed in claim 1, wherein The state switching valve includes a state switching valve one, a state switching valve two and a state switching valve three; the paver further includes an electrically regulated boosting valve; Both the two inlets of the state switching valve one are connected to the oil return tank, and the two outlets are respectively connected to the lifting chamber and the lowering chamber of the two lifting cylinders; Both the two inlets of the state switching valve two are respectively connected to the pressure oil and the oil return tank, and the outlet is connected to the inlet of the electrically regulated loading valve; the outlet of the electrically regulated loading valve is connected to the lowering chamber of the two lifting cylinders; Both the two inlets of the state switching valve three are respectively connected to the pressure oil and the oil return tank, and the outlet is connected to the inlet of the electrically regulated boosting valve; the outlet of the electrically regulated loading valve is connected to the lifting chamber of the two lifting cylinders; The electrically regulated boosting valve is used to regulate the pressure of the lifting cylinder lifting chamber in the paving stop state.

10. The paving control method of the paving machine according to any one of claims 1 to 9, characterized in that, It includes: Obtain the state of the paver, If the paver is switched from the paving stop state to the normal paving state, control the on-off of the state switching valve to make the lifting chamber of the lifting cylinder in the pressure-free state and the lowering chamber in the pressure state, and control the electrically regulated loading valve to regulate the pressure of the lifting cylinder lowering chamber based on the paving stop time; After a set time, control the state switching valve to make the lifting chamber and the lowering chamber of the lifting cylinder both in the pressure-free state.

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