Asphalt paver

Abstract

The present disclosure provides an asphalt finisher capable of improving the accuracy of rudder angle control. The asphalt finisher is provided with a plurality of wheels including a steering wheel, a steering cylinder (54) that adjusts the rudder angle of the steering wheel, and a hydraulic pump (55) that supplies working oil to the steering cylinder (54). Furthermore, the asphalt finisher is provided with a proportional control valve (56p) disposed between the hydraulic pump (55) and the steering cylinder (54) and controlling the flow rate and direction of the working oil supplied to the steering cylinder (54), and a controller that controls the rudder angle by controlling the proportional control valve (56p).

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2024-206092, filed on November 27, 2024. The entire contents of that Japanese application are incorporated herein by reference.

[0002] This disclosure relates to an asphalt rolling machine. Background Technology

[0003] Previously, wheeled construction machinery was known to control the rudder angle of the steering wheel based on the operation of a handle (see Patent Document 1 below). The construction machinery described in Patent Document 1 controls the rudder angle of the steering wheel by switching the direction of the working oil supplied to the steering cylinder through a direction switching valve.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-113611 As described in Patent Document 1 above, when a direction switching valve is used in the rudder angle control of the steering wheel of the construction machinery, there is a problem of improving the accuracy of rudder angle control. Summary of the Invention

[0005] This disclosure provides an asphalt leveling machine that can improve the accuracy of rudder angle control.

[0006] This disclosure provides an asphalt tumbling machine comprising: a plurality of wheels, including a steering wheel; a steering cylinder for adjusting the rudder angle of the steering wheel; a hydraulic pump for supplying working oil to the steering cylinder; a proportional control valve disposed between the hydraulic pump and the steering cylinder for controlling the flow rate and direction of the working oil supplied to the steering cylinder; and a controller for controlling the rudder angle by controlling the proportional control valve.

[0007] Invention Effects According to embodiments of this disclosure, an asphalt tumbler can be provided that improves the accuracy of rudder angle control. Attached Figure Description

[0008] Figure 1 This is a side view of the asphalt roller according to the embodiments of this disclosure.

[0009] Figure 2 yes Figure 1 A top view of an asphalt roller.

[0010] Figure 3 This is a diagram showing an example of the structure of an automatic steering system.

[0011] Figure 4 This is a circuit diagram showing the structure of the steering mechanism of an automatic steering system.

[0012] Figure 5This is the hydraulic circuit diagram of the steering system.

[0013] Figure 6 It is shown Figure 4 A circuit diagram of a modified steering mechanism.

[0014] Figure 7 This is an overhead view of the construction site.

[0015] Figure 8 This is an overhead view of the construction site.

[0016] Figure 9A This is an overhead view of the construction site.

[0017] Figure 9B This is an overhead view of the construction site.

[0018] In the diagram: 5-rear wheel (wheel), 6-front wheel (steering wheel / wheel), 50-controller, 54-steering cylinder, 55-hydraulic pump, 56p-proportional control valve, 57-manual steering device, 58-rudder angle sensor, 59-steering angle sensor, 100-asphalt roller, SH-steering handle, W-wheel. Detailed Implementation

[0019] Figure 1 This is a side view of the asphalt roller 100 according to the embodiments of this disclosure. Figure 2 This is a top view of the asphalt roller 100.

[0020] In this embodiment, the asphalt roller 100 is a wheeled asphalt roller, equipped with multiple wheels W, including a rear wheel 5 and a front wheel 6. The front wheel 6 is a steering wheel for changing the direction of travel of the asphalt roller 100. The asphalt roller 100 mainly consists of a traction machine 1, a hopper 2, and a leveling machine 3. Hereinafter, the direction of the hopper 2 (+X direction) as viewed from the traction machine 1 will be defined as the front, and the direction of the leveling machine 3 (-X direction) as viewed from the traction machine 1 will be defined as the rear.

[0021] The traction unit 1 is a mechanism for moving the asphalt roller 100. In this embodiment, the traction unit 1 uses a rear-wheel travel hydraulic motor to rotate the rear wheel 5 and a front-wheel travel hydraulic motor to rotate the front wheel 6, thereby moving the asphalt roller 100. The rear-wheel travel hydraulic motor and the front-wheel travel hydraulic motor rotate by receiving working oil from a hydraulic pump. However, the front wheel 6 can also be a driven wheel.

[0022] The asphalt trolley 100 can be a tracked asphalt trolley. In this case, the combination of the rear wheel 5 and the front wheel 6 is replaced by a combination of the left track and the right track.

[0023] The controller 50 is a control device for controlling the asphalt roller 100. In this embodiment, the controller 50 is composed of a microcomputer including a CPU, volatile memory, and non-volatile memory, and is mounted on the traction machine 1. The CPU executes the program stored in the non-volatile memory, thereby realizing the various functions of the controller 50. However, the various functions of the controller 50 can be implemented not only by software, but also by hardware, or by a combination of hardware and software.

[0024] The hopper 2 is a mechanism for receiving paving materials. In this embodiment, the hopper 2 is located in front of the tractor 1 and is configured to open and close in the vehicle width direction (Y-axis direction) via a hopper cylinder. Typically, the asphalt roller 100 receives paving materials (e.g., asphalt mixture) from the cargo box of the dump truck when the hopper 2 is fully open. The dump truck is an example of a transport vehicle for transporting paving materials. Figure 1 and Figure 2 The diagram shows hopper 2 in a fully open state. If the paving material in hopper 2 decreases, hopper 2 closes, and the paving material near the inner wall of hopper 2 concentrates in the center of hopper 2. This is to allow the conveyor CV, located in the center of hopper 2, to supply paving material to the rear of the tractor 1. Paving material is supplied to the rear of the tractor 1 via screw SC along the vehicle width direction from the rear of the tractor 1 and the front of the leveler 3. In this embodiment, screw SC is connected to extended screws on both sides. Figure 1 and Figure 2 The illustration of the paving material existing in the hopper 2 is omitted. The paving material PV spread by the screw SC is represented by coarse dot patterns, and the newly installed paving body NP is represented by fine dot patterns.

[0025] The leveling machine 3 is a mechanism for spreading paving material PV evenly. In this embodiment, the leveling machine 3 includes a front leveling machine 30 and a rear leveling machine 31. The front leveling machine 30 includes a left front leveling machine 30L and a right front leveling machine 30R. The rear leveling machine 31 is a leveling machine capable of extending and retracting along the vehicle width direction, including a left rear leveling machine 31L and a right rear leveling machine 31R. However, the rear leveling machine 31 can be a fixed-width leveling machine that is connected to the front leveling machine 30 on both sides. Furthermore, the leveling machine 3 is a floating leveling machine towed by a tractor 1 and is connected to the tractor 1 via a leveling arm 3A. The leveling arm 3A includes a left leveling arm 3AL disposed on the left side of the tractor 1 and a right leveling arm 3AR disposed on the right side of the tractor 1.

[0026] A plow plate 43 is installed at the front of the screed 3. The plow plate 43 is configured to adjust the amount of paving material PV remaining in front of the screed 3. The paving material PV reaches the bottom of the screed 3 through the gap between the lower end of the plow plate 43 and the roadbed BS.

[0027] The tractor 1 is equipped with an information acquisition device 51, an on-board display device 52, and a steering device 53.

[0028] The information acquisition device 51 is configured to acquire road-related information concerning the construction object and output the acquired information to the controller 50. Road-related information includes, for example, the road width, changes in curvature in transition sections (boomerang sections), and curvature in circular arc sections. In this embodiment, the information acquisition device 51 includes a forward monitoring device 51F, a rear monitoring device 51B, a walking speed sensor 51S, a positioning device 51P, and a communication device 51T.

[0029] The forward monitoring device 51F is configured to monitor the front of the asphalt roller 100. In this embodiment, the forward monitoring device 51F is a LiDAR that monitors the monitoring range RF located in front of the tractor 1, and is installed in the center of the tractor 1. The center of the tractor 1 is, for example, the front center of the cover that covers the engine compartment located behind the hopper 2. However, the forward monitoring device 51F can be installed in other parts of the asphalt roller 100, or it can be composed of multiple LiDARs. When composed of multiple LiDARs, the forward monitoring device 51F can simultaneously monitor multiple non-overlapping monitoring ranges. In this case, the multiple LiDARs may include a right front LiDAR installed on the right side of the front of the tractor 1 and a left front LiDAR installed on the left side of the front of the tractor 1. Furthermore, the LiDARs can be mounted on the tractor 1 via brackets or poles.

[0030] The rear monitoring device 51B is configured to monitor the rear of the asphalt trolley 100. In this embodiment, the rear monitoring device 51B is a LiDAR that monitors the monitoring range RB located behind the leveler 3, and is mounted on the guide rail 1G, which functions as a handrail. However, the rear monitoring device 51B can be mounted on the lower part of the driver's seat 1S, or on other parts of the asphalt trolley 100. Furthermore, the rear monitoring device 51B can be composed of multiple LiDARs. When composed of multiple LiDARs, the rear monitoring device 51B can simultaneously monitor multiple non-overlapping monitoring ranges. In this case, the multiple LiDARs may include a right rear LiDAR mounted on the right side of the rear end of the tractor 1 and a left rear LiDAR mounted on the left side of the rear end of the tractor 1. Furthermore, the LiDARs can be mounted on the tractor 1 via brackets or poles, etc.

[0031] The information acquisition device 51 may include a side monitoring device configured to monitor the side of the asphalt roller 100. In this case, the side monitoring device may include a left side monitoring device and a right side monitoring device. The left side monitoring device may, for example, be a LiDAR monitoring device that monitors the area to the left of the tractor 1, mounted on the left end of the upper surface of the tractor 1, further forward of the rear wheel 5. The right side monitoring device may, for example, be a LiDAR monitoring device that monitors the area to the right of the tractor 1, mounted on the right end of the upper surface of the tractor 1, further forward of the rear wheel 5.

[0032] For example, a LiDAR can be configured to determine the distance between itself and multiple points within its monitoring range. However, at least one of the front monitoring device 51F and the rear monitoring device 51B can be a monocular camera, a stereo camera, a millimeter-wave radar, a lidar, a laser scanner, a distance imaging camera, or a laser rangefinder, etc. The same applies to the side monitoring device.

[0033] The monitoring range RF of the forward monitoring device 51F preferably includes the roadbed BS and the above-ground structures AP located outside the roadbed BS. This is to obtain information related to the width of the road to be constructed. The same applies to the monitoring range of the lateral monitoring device. In this embodiment, the monitoring range RF has a width greater than the width of the roadbed BS. The above-ground structures AP are L-shaped side blocks. The above-ground structures AP can be paving frames, curb stones, or existing paving structures, etc.

[0034] The monitoring range RB of the rear monitoring device 51B preferably includes the newly installed pavement NP and the ground features AP located outside the newly installed pavement NP. This is to obtain information related to the width of the newly installed pavement NP. In this embodiment, the monitoring range RB has a width greater than the width of the newly installed pavement NP.

[0035] The travel speed sensor 51S is configured to detect the travel speed of the asphalt roller 100. In this embodiment, the travel speed sensor 51S is a wheel speed sensor, configured to detect the rotational angular velocity and rotational angle of the rear wheel 5, as well as the travel speed and travel distance of the asphalt roller 100.

[0036] The positioning device 51P is configured to measure the position of the asphalt roller 100. In this embodiment, the positioning device 51P is a GNSS compass, configured to measure both the position and orientation of the asphalt roller 100. Figure 1 and Figure 2As shown, the GNSS compass, which serves as the positioning device 51P, includes a left GNSS receiver 51PL and a right GNSS receiver 51PR. The left GNSS receiver 51PL is mounted on the upper end of a pole PL that extends vertically upward from the rear end of the left leveling arm 3AL. The right GNSS receiver 51PR is mounted on the upper end of a pole PL (not visible) that extends vertically upward from the rear end of the right leveling arm 3AR.

[0037] However, the positioning device 51P can be a total station. In this case, a reflecting prism serving as the target of the total station is installed at the front end of the pole PL. The main body of the total station, positioned around the asphalt tumbler 100, is connected to the controller 50 via wireless communication. That is, the main body of the total station sends information related to the position of the derived target to the controller 50.

[0038] The communication device 51T is configured to control communication between the asphalt roller 100 and equipment located outside the asphalt roller 100. In this embodiment, the communication device 51T is located in front of the driver's seat 1S and is configured to control communication via mobile communication networks, short-range wireless communication networks, or satellite communication networks.

[0039] The information acquisition device 51 may include a steering angle sensor configured to detect the steering angle of the asphalt roller 100 and a paving width sensor configured to detect the extension and retraction of the rear screed 31 and calculate the paving width, etc.

[0040] Furthermore, the information acquisition device 51 may include a monitoring device installed at the construction site or a monitoring device mounted on an aircraft flying above the asphalt roller 100. The monitoring device installed at the construction site may be, for example, a LiDAR or monocular camera mounted on the front end of a pole installed along the road surface of the construction object. The monitoring device mounted on the aircraft may be, for example, a LiDAR or monocular camera mounted on a multi-rotor aircraft (drone) or airship.

[0041] The vehicle-mounted display device 52 is configured to display information related to the asphalt tumbler 100. In this embodiment, the vehicle-mounted display device 52 is a liquid crystal display located in front of the driver's seat 1S. However, the vehicle-mounted display device 52 may be located at at least one end of the tumbler 3, either the left or right end.

[0042] The steering device 53 is configured to control the steering of the asphalt trolley 100. In this embodiment, the steering device 53 is configured to extend and retract the steering cylinder located near the front axle. Details will be described later, but the steering device 53 includes a steering electromagnetic proportional control valve that controls the flow rate of working oil from the hydraulic pump to the steering cylinder and the flow rate of working oil discharged from the steering cylinder. The proportional control valve is configured to control the flow of working oil in the steering cylinder based on the rotation of the steering handle SH (steering wheel), which is an operating device. Furthermore, the proportional control valve is configured to control the flow of working oil in the steering cylinder independently of the rotation of the steering handle SH, based on control commands from the controller 50. That is, the controller 50 can control the steering of the asphalt trolley 100 regardless of whether the driver operates the steering handle SH.

[0043] Next, refer to Figures 3 to 6 An example of the structure of the automatic steering system DS mounted on the asphalt roller 100 will be described. Figure 3 This is a block diagram illustrating a structural example of an automatic steering system (DS).

[0044] The automatic steering system DS mainly consists of a controller 50, a forward monitoring device 51F, a rear monitoring device 51B, a travel speed sensor 51S, a positioning device 51P, a communication device 51T, an on-board display device 52, and a steering device 53.

[0045] Figure 4 This is a circuit diagram schematically showing the structure of the steering device 53 and the steering mechanism 7. Figure 5 This is the hydraulic circuit diagram for steering gear 53. Additionally, in Figure 4 The middle part is omitted Figure 5 The diagram shows the hydraulic pump 55, power source 8, working oil tank 9, etc.

[0046] like Figure 4 As shown, the asphalt trolley 100 includes a steering mechanism 7 that can change the rudder angle via a steering device 53. The rudder angle changed by the steering mechanism 7 is the angle of the steering wheel relative to the straight-line direction (front and rear axles) of the asphalt trolley 100, i.e., the actual rudder angle. The steering wheel of the asphalt trolley 100 is, for example, the front wheel 6.

[0047] The steering device 53 includes, for example, a steering cylinder 54, a hydraulic pump 55, and an automatic steering device 56. Furthermore, the steering device 53 includes, for example, a steering handle SH and a manual steering device 57. Additionally, the steering device 53 may include, for example, a rudder angle sensor 58 for detecting the rudder angle.

[0048] The steering cylinder 54 is, for example, a double-rod hydraulic cylinder for adjusting the rudder angle of the steering wheel, i.e., the front wheel 6. The steering cylinder 54 has a cylinder tube 54c, a piston 54p, and a rod 54r. Alternatively, the steering cylinder 54 can be replaced by two single-rod hydraulic cylinders, one on the left and one on the right.

[0049] The cylinder tube 54c is a hollow cylindrical component with through holes at both ends through which the rod 54r is inserted in the direction of the central axis. For example... Figure 5 As shown, piston 54p is housed in cylinder tube 54c, and left and right oil chambers are formed inside cylinder tube 54c. Rod 54r is integral with piston 54p and extends to the left and right sides of piston 54p. Rod 54r and piston 54p are configured to move left and right along the central axis of cylinder tube 54c.

[0050] like Figure 5 As shown, the hydraulic pump 55 is driven, for example, by a power source 8 such as an engine or electric motor mounted on the asphalt tumbler 100. The hydraulic pump 55 supplies working oil from the working oil tank 9 mounted on the asphalt tumbler 100 to the steering cylinder 54. The hydraulic pump 55 is, for example, a variable capacity type hydraulic pump whose discharge flow rate can be controlled by adjusting the deflection angle of the swashplate.

[0051] like Figure 4 As shown, the steering mechanism 7 includes, for example, a half shaft 71, left and right steering knuckles 72L and 72R, left and right steering pins 73L and 73R, and left and right tie rods 74L and 74R.

[0052] The half-shaft 71 is mounted, for example, on the body of the asphalt roller 100 and positioned below the hopper 2. The left steering knuckle 72L is rotatably mounted on the left end of the half-shaft 71 via the left steering pin 73L and supports the left front wheel 6. The right steering knuckle 72R is rotatably mounted on the right end of the half-shaft 71 via the right steering pin 73R and supports the right front wheel 6.

[0053] One end of the left tie rod 74L is connected to the left steering knuckle 72L. The other end of the left tie rod 74L is rotatably connected to the front end of the rod 54r, which extends to the left from the left end of the cylinder tube 54c of the steering cylinder 54. One end of the right tie rod 74R is connected to the right steering knuckle 72R. The other end of the right tie rod 74R is rotatably connected to the front end of the rod 54r, which extends to the right from the right end of the cylinder tube 54c of the steering cylinder 54.

[0054] According to this structure, if the rod 54r of the steering cylinder 54 moves to the right, the left and right steering knuckles 72L and 72R rotate to the left (counterclockwise) around the left and right steering pins 73L and 73R. As a result, the rudder angle of the left and right front wheels 6 and 6, supported by the left and right steering knuckles 72L and 72R, relative to the straight-line direction, increases to the left.

[0055] Furthermore, if the rod 54r of the steering cylinder 54 moves to the left, the left and right steering knuckles 72L and 72R rotate to the right (clockwise) around the left and right steering pins 73L and 73R. As a result, the rudder angle of the left and right front wheels 6 and 6, supported by the left and right steering knuckles 72L and 72R, relative to the straight-line direction, increases to the right.

[0056] The steering handle SH is used for manual operation of the rudder angle of the asphalt trolley 100. The steering handle SH is connected, for example, via a steering column (not shown) to... Figure 5 The metering device 57m of the manual steering device 57 shown is connected. If the operator of the asphalt roller 100 rotates the steering handle SH, the metering device 57m of the manual steering device 57 will rotate according to the rotation direction, rotation angle and speed of the steering handle SH.

[0057] like Figure 5 As shown, the manual steering device 57 is arranged side-by-side with the automatic steering device 56 between the hydraulic pump 55 and the steering cylinder 54. For example, ORBITROL (registered trademark) manufactured by Eaton can be used as the manual steering device 57. The manual steering device 57 controls the flow rate and direction of the hydraulic oil supplied from the hydraulic pump 55 to the steering cylinder 54 according to the driver's operation of the steering handle SH.

[0058] Details will be described later, but when the driver operates the steering handle SH, the controller 50 closes the proportional control valve 56p of the automatic steering system 56 to prioritize manual operation. By closing the proportional control valve 56p, the flow path of hydraulic oil from the hydraulic pump 55 through the automatic steering system 56 to the steering cylinder 54 is cut off. Furthermore, by closing the proportional control valve 56p, the flow path of hydraulic oil from the steering cylinder 54 through the automatic steering system 56 to the hydraulic oil reservoir 9 is also cut off.

[0059] The manual steering device 57 includes, for example, a direction control valve 57d, a check valve 57c, and a metering device 57m. Furthermore, the manual steering device 57 has four ports. Specifically, these are the P port connected to the hydraulic pump 55, the T port connected to the working oil reservoir 9, the L port connected to the left oil chamber of the steering cylinder 54, and the R port connected to the right oil chamber of the steering cylinder 54.

[0060] The directional control valve 57d is, for example, a 3-position 6-way directional control valve. With the steering handle SH in the neutral position and the metering device 57m in the neutral position, the valve stem of the directional control valve 57d is in the first position. In the first position, the directional control valve 57d closes the flow path between the P port and the L and R ports of the manual steering device 57, and also closes the flow path between the L and R ports and the T port of the manual steering device 57.

[0061] Therefore, when the valve stem of the directional control valve 57d is in the first position, the flow path of the working oil from the hydraulic pump 55 to the steering cylinder 54 via the manual steering device 57 is cut off by the directional control valve 57d. Similarly, the flow path of the working oil from the steering cylinder 54 to the working oil reservoir 9 via the manual steering device 57 is cut off by the directional control valve 57d. Therefore, when the automatic steering device 56 is not automatically controlling the rudder angle and the valve stem of the directional control valve 57d is in the first position, the piston 54p and rod 54r of the steering cylinder 54 will not move left or right.

[0062] On the other hand, if the steering handle SH is rotated to the left, causing the metering device 57m to rotate to the left, the valve stem of the direction control valve 57d moves to the second position. In the second position of the valve stem, the direction control valve 57d connects the P port of the manual steering device 57 to the right flow path of the metering device 57m, and connects the left flow path of the metering device 57m to the L port of the manual steering device 57. Furthermore, in the second position of the valve stem, the direction control valve 57d connects the R port and T port of the manual steering device 57.

[0063] Therefore, when the steering handle SH is turned to the left, the working oil discharged from the hydraulic pump 55 flows into the left oil chamber of the steering cylinder 54 through the P port, metering device 57m, and L port of the manual steering device 57. At this time, the flow rate of the working oil corresponds to the rotation angle of the metering device 57m, that is, the amount of operation of the steering handle SH. Furthermore, the pressure of the working oil rises in the left oil chamber of the steering cylinder 54, and the piston 54p moves to the right, thereby squeezing the working oil out of the right oil chamber of the steering cylinder 54 and returning to the working oil reservoir 9 through the R port and T port of the manual steering device 57.

[0064] As described above, if the steering handle SH is turned to the left, the hydraulic oil discharged from the hydraulic pump 55 flows into the left oil chamber of the steering cylinder 54 via the manual steering device 57. Furthermore, the hydraulic oil flowing from the right oil chamber of the steering cylinder 54 returns to the hydraulic oil reservoir 9 via the manual steering device 57. As a result, the rod 54r of the steering cylinder 54 moves to the right along with the piston 54p, causing... Figure 4 The ends of the left and right tie rods 74L and 74R, which are connected to rod 54r, move to the right. As a result, the left and right steering knuckles 72L and 72R, which are connected to the tie rods 74L and 74R, rotate to the left (counter-clockwise) around the steering pins 73L and 73R. Then, the steering angle of the left and right front wheels 6, 6, supported by the steering knuckles 72L and 72R, increases to the left.

[0065] Furthermore, if the steering handle SH is rotated to the right, causing the metering device 57m to rotate to the right, the valve stem of the direction control valve 57d moves to the third position. In the third position, the direction control valve 57d connects the P port of the manual steering device 57 to the left flow path of the metering device 57m, and connects the right flow path of the metering device 57m to the R port of the manual steering device 57. Also in the third position, the direction control valve 57d connects the L port and T port of the manual steering device 57.

[0066] Therefore, when the steering handle SH is turned to the right, the working oil discharged from the hydraulic pump 55 flows into the right oil chamber of the steering cylinder 54 through the P port, metering device 57m, and R port of the manual steering device 57. At this time, the flow rate of the working oil corresponds to the rotation angle of the metering device 57m, that is, the operating amount of the steering handle SH. Furthermore, the pressure of the working oil rises in the right oil chamber of the steering cylinder 54, and the piston 54p moves to the left, thereby squeezing the working oil out of the left oil chamber of the steering cylinder 54 and returning to the working oil reservoir 9 through the L port and T port of the manual steering device 57.

[0067] As described above, if the steering handle SH is turned to the right, the hydraulic oil discharged from the hydraulic pump 55 flows into the right oil chamber of the steering cylinder 54 via the manual steering device 57. Furthermore, the hydraulic oil flowing from the left oil chamber of the steering cylinder 54 returns to the hydraulic oil reservoir 9 via the manual steering device 57. As a result, the rod 54r of the steering cylinder 54 moves to the left along with the piston 54p, causing... Figure 4 The ends of the left and right tie rods 74L and 74R, which are connected to rod 54r, move to the left. This causes the left and right steering knuckles 72L and 72R, which are connected to the tie rods 74L and 74R, to rotate to the right (clockwise) around the steering pins 73L and 73R. Then, the steering angle of the left and right front wheels 6, 6, supported by the steering knuckles 72L and 72R, increases to the right.

[0068] like Figure 5 As shown, check valve 57c is located in the flow path connecting the T port and P port of the manual steering device 57. Check valve 57c cuts off the flow of working oil from port P to port T, while allowing the flow of working oil from port T to port P. Thus, for example, in the event of a failure of the hydraulic pump 55, the steering angle can be changed by rotating the steering handle SH, thereby rotating the metering device 57m and supplying working oil to the left and right oil chambers of the steering cylinder 54.

[0069] An automatic steering device 56 is configured alongside a manual steering device 57, for example, on the path of the working oil between the hydraulic pump 55 and the steering cylinder 54. For instance, during automatic driving of the asphalt trolley 100 based on the controller 50, the automatic steering device 56 controls the flow rate and direction of the working oil supplied from the hydraulic pump 55 to the steering cylinder 54 according to control commands from the controller 50. Thus, the automatic steering device 56 automatically operates the steering mechanism 7 and automatically controls the steering angle.

[0070] like Figure 5 As shown, the automatic steering device 56 includes, for example, a fixed throttle 56f, a proportional control valve 56p, and a check valve 56c. Furthermore, the automatic steering device 56 has a P port connected to the hydraulic pump 55 via a hydraulic hose and a T port connected to the hydraulic reservoir 9 via a hydraulic hose. Additionally, the automatic steering device 56 has an A port connected to the right hydraulic chamber of the steering cylinder 54 via a hydraulic hose and a B port connected to the left hydraulic chamber of the steering cylinder 54 via a hydraulic hose.

[0071] A fixed throttle 56f restricts the flow path of the working oil connecting the P port of the automatic steering unit 56 and the P port of the proportional control valve 56p with a predetermined orifice, thereby applying resistance to the working oil and controlling its flow rate. This prevents abrupt movement of the steering cylinder 54, which supplies working oil via the automatic steering unit 56.

[0072] A proportional control valve 56p is positioned between the hydraulic pump 55 and the steering cylinder 54, controlling the flow rate and direction of the hydraulic fluid supplied to the steering cylinder 54. The proportional control valve 56p is, for example, a 3-position 4-way solenoid proportional directional control valve. Specifically, the proportional control valve 56p has four ports: P port, T port, A port, and B port. Each port of the proportional control valve 56p is connected to a corresponding port of the automatic steering unit 56. Furthermore, the automatic steering unit 56 operates the solenoid according to control commands from the controller 50, thereby switching the position of the valve stem to position 1, position 2, or position 3.

[0073] For example, when the driver manually drives by operating the steering handle SH or when the controller 50 controls the steering angle to maintain a constant steering angle during automatic driving, the proportional control valve 56p moves the valve stem to the first position. The first position of the valve stem of the proportional control valve 56p is the position where the P port of the proportional control valve 56p is disconnected from other ports, and the A and B ports of the proportional control valve 56p are connected to the T port.

[0074] Working oil discharged from hydraulic pump 55 is introduced through the P port of automatic steering device 56 and flows into the P port of proportional control valve 56p through fixed throttle 56f. When the valve stem of proportional control valve 56p is in the first position, the flow of working oil into the P port of proportional control valve 56p is cut off by the valve stem, thus preventing it from flowing into steering cylinder 54. Furthermore, the flow of working oil from steering cylinder 54 to working oil reservoir 9 via automatic steering device 56 is cut off by check valve 56c.

[0075] Furthermore, if the steering lever SH is not operated, the flow of working oil from the hydraulic pump 55 to the steering cylinder 54 via the manual steering device 57 is cut off by the manual steering device 57. Similarly, if the steering lever SH is not operated, the flow of working oil from the steering cylinder 54 to the working oil reservoir 9 via the manual steering device 57 is cut off by the manual steering device 57. Therefore, when the valve stem of the proportional control valve 56p is in the first position and the steering lever SH is not operated, the piston 54p and rod 54r of the steering cylinder 54 do not move, and the rudder angle of the steering wheel, i.e., the front wheel 6, is maintained.

[0076] Furthermore, according to the control command from the controller 50 to increase the rudder angle to the left, the proportional control valve 56p moves its valve stem to the second position. The second position of the valve stem of the proportional control valve 56p is the position where the P port and B port of the proportional control valve 56p are connected, and the A port and T port of the proportional control valve 56p are connected. Furthermore, when the valve stem is in the second position, the proportional control valve 56p proportionally controls the opening of the flow paths connecting each port according to the control command from the controller 50.

[0077] Working oil discharged from hydraulic pump 55 is introduced through port P of automatic steering unit 56 and flows into port P of proportional control valve 56p through fixed throttle 56f. With the valve stem of proportional control valve 56p in position 2, the working oil flowing into port P of proportional control valve 56p is regulated to a flow rate corresponding to the opening of proportional control valve 56p and discharged from port B of proportional control valve 56p. Then, the working oil is discharged from port B of automatic steering unit 56 through check valve 56c and flows into the left oil chamber of steering cylinder 54.

[0078] As a result, the pressure of the working oil in the left oil chamber of the steering cylinder 54 increases, the piston 54p moves to the right, and the working oil is squeezed out from the right oil chamber of the steering cylinder 54. The working oil squeezed out from the right oil chamber of the steering cylinder 54 returns to the working oil reservoir 9 via the A port of the automatic steering device 56, the check valve 56c, the A and T ports of the proportional control valve 56p, and the T port of the automatic steering device 56. Additionally, when the working oil flows from the B port of the proportional control valve 56p to the B port of the automatic steering device 56, the check valve 56c allows the working oil to flow from the A port of the automatic steering device 56 to the A port of the proportional control valve 56p.

[0079] Therefore, if a control command to increase the steering angle to the left is input from controller 50 to proportional control valve 56p, hydraulic oil flows from hydraulic pump 55 into the left oil chamber of steering cylinder 54 via automatic steering device 56. Simultaneously, hydraulic oil flows from the right oil chamber of steering cylinder 54 into hydraulic oil reservoir 9 via automatic steering device 56. As a result, rod 54r of steering cylinder 54 moves to the right along with piston 54p, causing... Figure 4 The ends of the left and right tie rods 74L and 74R, which are connected to rod 54r, move to the right. As a result, the left and right steering knuckles 72L and 72R, which are connected to the tie rods 74L and 74R, rotate to the left (counter-clockwise) around the steering pins 73L and 73R. Then, the steering angle of the left and right front wheels 6, 6, supported by the steering knuckles 72L and 72R, increases to the left.

[0080] Furthermore, according to the control command from the controller 50 to increase the rudder angle to the right, the proportional control valve 56p moves its valve stem to position 3. Position 3 of the proportional control valve 56p's valve stem is the position where port P and port A of the proportional control valve 56p are connected, and port B and port T of the proportional control valve 56p are connected. Furthermore, when the valve stem is in position 3, the proportional control valve 56p proportionally controls the opening of the flow paths connecting each port according to the control command from the controller 50.

[0081] Working oil discharged from hydraulic pump 55 is introduced through port P of automatic steering unit 56 and flows into port P of proportional control valve 56p through fixed throttle 56f. With the valve stem of proportional control valve 56p in position 3, the working oil flowing into port P of proportional control valve 56p is adjusted to a flow rate corresponding to the opening of proportional control valve 56p and discharged from port A of proportional control valve 56p. Then, the working oil is discharged from port A of automatic steering unit 56 through check valve 56c and flows into the right oil chamber of steering cylinder 54.

[0082] As a result, the pressure of the working oil in the right oil chamber of the steering cylinder 54 increases, the piston 54p moves to the right, and the working oil is squeezed out from the left oil chamber of the steering cylinder 54. The working oil squeezed out from the left oil chamber of the steering cylinder 54 returns to the working oil reservoir 9 via port B of the automatic steering device 56, check valve 56c, ports B and T of the proportional control valve 56p, and port T of the automatic steering device 56. Additionally, when the working oil flows from port A of the proportional control valve 56p to port A of the automatic steering device 56, check valve 56c allows the working oil to flow from port B of the automatic steering device 56 to port B of the proportional control valve 56p.

[0083] Therefore, if a control command to increase the steering angle to the right is input from controller 50 to proportional control valve 56p, hydraulic oil flows from hydraulic pump 55 into the right oil chamber of steering cylinder 54 via automatic steering device 56. Simultaneously, hydraulic oil flows from the left oil chamber of steering cylinder 54 to hydraulic oil reservoir 9 via automatic steering device 56. As a result, rod 54r of steering cylinder 54 moves to the left along with piston 54p, causing... Figure 4 The ends of the left and right tie rods 74L and 74R, which are connected to rod 54r, move to the left. This causes the left and right steering knuckles 72L and 72R, which are connected to the tie rods 74L and 74R, to rotate to the right (clockwise) around the steering pins 73L and 73R. Then, the steering angle of the left and right front wheels 6, 6, supported by the steering knuckles 72L and 72R, increases to the right.

[0084] like Figure 4 As shown, the rudder angle sensor 58 detects the rudder angle of the steering wheel, i.e., the front wheel 6. In Figure 4 In the example shown, the rudder angle sensor 58 is an angle sensor capable of detecting the rudder angle of the front wheel 6 by detecting the angle of the left tie rod 74L relative to the rod 54r. Alternatively, the rudder angle sensor 58 can detect the rudder angle of the front wheel 6, for example, by detecting the rotation angle of the left and right steering knuckles 72L and 72R centered on the left and right steering pins 73L and 73R.

[0085] Figure 6 This refers to a variation of the aforementioned steering device 53. Figure 4 The corresponding loop diagram. Figure 6 The steering device 53A involved in the modified example shown is... Figure 4 The steering device 53 shown differs in that it has a steering angle sensor 59 instead of a manual steering device 57. Other structural features of the steering device 53A are similar to... Figure 4 The steering device 53 shown is the same, so the same parts are marked with the same symbols and the description is omitted.

[0086] A steering angle sensor 59 is installed, for example, on the steering column of the steering handle SH, to detect the steering angle of the steering handle SH. The steering angle is the rotation angle of the steering handle SH when it is operated. The steering angle sensor 59 detects the rotation direction and the amount of operation of the steering handle SH as the steering angle. The steering angle sensor 59 can, for example, detect angular velocity, angular acceleration, torque, etc., when the steering handle SH is operated. The steering angle sensor 59 outputs a signal corresponding to the detected steering angle to the controller 50.

[0087] Next, the controller 50 that controls the aforementioned steering device 53 or steering device 53A will be described. Figure 3 In the example shown, the controller 50 includes a target calculation unit 50a, a steering control unit 50b, and a display control unit 50c as functional modules.

[0088] The target calculation unit 50a is configured to calculate the target used by the steering control unit 50b. The target used by the steering control unit 50b is, for example, a target track that needs to be drawn as a predetermined point on the asphalt roller 100. The predetermined point is a point that is pre-associated with a predetermined location on the asphalt roller 100, also referred to as a steering reference point or control reference point. However, the predetermined point can be a point that is dynamically associated with a predetermined location on the asphalt roller 100. Strictly speaking, the target track is a one-dimensional arrangement of multiple target positions. The target position is the location that the predetermined point on the asphalt roller 100 needs to reach. Alternatively, the target used by the steering control unit 50b can be a target position that the predetermined point on the asphalt roller 100 needs to reach after a predetermined time has elapsed. The predetermined time is, for example, a few milliseconds, tens of milliseconds, hundreds of milliseconds, or a few seconds.

[0089] In this embodiment, the target calculation unit 50a calculates the target track that a predetermined point in the center of the tractor 1 must follow, for example, based on road-related information such as construction design data. Typically, the target track is calculated before the asphalt roller 100 begins to move. Therefore, the target track can be calculated by a server or similar device located in a management center outside the asphalt roller 100 and then transmitted to the controller 50 via communication. Furthermore, the predetermined point can be a point set at the center of the front end of the hopper 2, rather than a point set at the center of the tractor 1. In the case of a wheeled asphalt roller, the predetermined point can be a point set at the position of the left front wheel, a point set at the position of the right front wheel, or a point set at the center of the front axle.

[0090] The target calculation unit 50a can calculate the target position, which is the location that a predetermined point in the center of the tractor 1 needs to reach after a predetermined time has elapsed. At this time, the target position is repeatedly calculated at predetermined control cycles during the movement of the asphalt roller 100. For example, the target calculation unit 50a can calculate the target position as the center point in the width direction of the road of the construction object located at a predetermined distance ahead of the current position of the predetermined point in the center of the tractor 1, based on information obtained from the forward monitoring device 51F. The predetermined distance is, for example, a few centimeters or tens of centimeters. In this case, the target calculation unit 50a can calculate the target position without obtaining construction design data. However, the target calculation unit 50a can calculate the target position based on construction design data and information obtained from the forward monitoring device 51F. For example, the target calculation unit 50a can correct the target position calculated based on the construction design data based on information obtained from the forward monitoring device 51F. Furthermore, the target calculation unit 50a can utilize information obtained from the rear monitoring device 51B.

[0091] The steering control unit 50b is configured to automatically control the steering of the asphalt tumbler 100 without operating the control device.

[0092] In this embodiment, the steering control unit 50b outputs control commands to the steering device 53 to cause a predetermined point in the center of the tractor 1 to follow the target track calculated by the target calculation unit 50a. Specifically, the steering control unit 50b calculates the current position of the predetermined point in the center of the tractor 1 based on the output of the positioning device 51P. Furthermore, if it is determined that the predetermined point has deviated from the target track to the right, the steering control unit 50b outputs control commands to the steering device 53 to cause the asphalt roller 100 to move to the left. Similarly, if it is determined that the predetermined point has deviated from the target track to the left, the steering control unit 50b outputs control commands to the steering device 53 to cause the asphalt roller 100 to move to the right.

[0093] Alternatively, the steering control unit 50b can output control commands to the steering device 53 to position a predetermined point in the center of the tractor 1 at the target position calculated by the target calculation unit 50a. In this case, the steering control unit 50b can derive the current position of the predetermined point in the center of the tractor 1 based on the output of the positioning device 51P. Furthermore, the current position of the predetermined point in the center of the tractor 1 can be derived based on the output of at least one of the rear monitoring device 51B and the front monitoring device 51F. In the latter case, the positioning device 51P can be omitted.

[0094] The control commands output by the steering control unit 50b to the steering device 53 or steering device 53A include control commands for the rudder angle of the automatic steering device 56 relative to the proportional control valve 56p. These rudder angle control commands may include, for example, commands to increase or decrease the rudder angle to the left or right in units of 0.1 degrees, 1 degree, or several degrees. The rudder angle control commands may also include, for example, control commands for the position and opening of the valve stem of the proportional control valve 56p of the automatic steering device 56, i.e., control commands for the direction and flow rate of the hydraulic fluid.

[0095] Next, refer to Figure 7 The function of moving the asphalt roller 100 along the target track is explained. Figure 7 This is a top view showing the construction site of an asphalt roller 100 passing through the curve (left bend) of road RD, which is the object under construction. Figure 7In this diagram, asphalt roller 100a represents the asphalt roller 100 at the start of construction, i.e., at point 1. Asphalt roller 100b represents the asphalt roller 100 at point 2, after a predetermined time elapsed from point 1. Similarly, asphalt roller 100c represents the asphalt roller 100 at point 3, after a predetermined time elapsed from point 2. Asphalt roller 100d represents the asphalt roller 100 at point 4, after a predetermined time elapsed from point 3. Asphalt roller 100e represents the asphalt roller 100 at point 5, after a predetermined time elapsed from point 4. Furthermore, for clarity, Figure 7 The diagram simplifies the asphalt roller 100, showing the tractor 1, the front leveler 30, the left rear leveler 31L, and the right rear leveler 31R. The hopper 2 is omitted from the illustration.

[0096] At the start of construction, i.e., at the first point in time, the target calculation unit 50a of the controller 50 calculates the target track TPT that the predetermined point P in the central part of the traction machine 1 needs to follow. Figure 7 In the example shown, the predetermined point P is represented by "○", and the target track TPT is represented by a dashed line. The target calculation unit 50a, referring to the construction design data, derives the centerline CP of the road RD based on the left boundary line LP and right boundary line RP of the road RD. Then, the target calculation unit 50a sets the centerline CP as the target track TPS that the predetermined point Q in the center of the front leveling machine 30 needs to follow. Figure 7 In the example shown, the predetermined point Q is represented by "△", and the target track TPS is represented by a dashed line. Then, the target calculation unit 50a calculates the target track TPT that the predetermined point P needs to follow based on known information, including the distance between the rear wheel 5 and the front wheel 6 of the asphalt roller 100, and the target track TPS.

[0097] exist Figure 7 In the example shown, the left boundary line LP, right boundary line RP, center line CP, target track TPT to be followed by predetermined point P, and target track TPS to be followed by predetermined point Q are all derived as a one-dimensional arrangement of multiple position coordinates. These position coordinates are, for example, coordinates in a reference coordinate system.

[0098] A reference coordinate system is, for example, the World Geodetic System. The World Geodetic System is a three-dimensional orthogonal coordinate system with its origin placed at the Earth's center of gravity. Specifically, the World Geodetic System is an XYZ rectangular coordinate system with the axis passing through the intersection of the Greenwich Meridian and the equator and the origin as the X-axis, the axis passing through the intersection of the meridian at 90 degrees east longitude and the equator and the origin as the Y-axis, and the axis passing through the North Pole and the origin as the Z-axis.

[0099] Then, the steering control unit 50b of the controller 50 causes the asphalt trolley 100 to operate in a manner that makes the actual position coordinates of the predetermined point P consistent with one of the position coordinates constituting the target track TPT. Specifically, the steering control unit 50b derives the current position of the predetermined point P in the center of the tractor 1 based on the output of the positioning device 51P.

[0100] Furthermore, when the predetermined point P is located to the right of the target track TPT, the steering control unit 50b outputs a control command to the proportional control valve 56p of the automatic steering device 56 constituting the steering device 53, increasing the rudder angle to the left. Consequently, the proportional control valve 56p moves the valve stem to the second position and adjusts the flow path of the working oil to a proportional opening to the control command, allowing a predetermined amount of working oil to flow from the hydraulic pump 55 into the left oil chamber of the steering cylinder 54. As a result, through the steering mechanism 7, the rudder angle of the left and right front wheels 6, 6 increases to the left, causing the asphalt tumbler 100 to move forward while simultaneously moving to the left, bringing the predetermined point P closer to the target track TPT.

[0101] Conversely, when the predetermined point P is located to the left of the target track TPT, the steering control unit 50b outputs a control command to the proportional control valve 56p of the automatic steering device 56 constituting the steering device 53, increasing the rudder angle to the right. The proportional control valve 56p then moves the valve stem to position 3 and adjusts the flow path of the working oil to a proportional opening to the control command, allowing a predetermined amount of working oil to flow from the hydraulic pump 55 into the right oil chamber of the steering cylinder 54. As a result, through the steering mechanism 7, the rudder angle of the left and right front wheels 6, 6 increases to the right, causing the asphalt trolley 100 to move forward and to the right simultaneously, bringing the predetermined point P closer to the target track TPT.

[0102] Thus, the controller 50 controls the rudder angle by controlling the proportional control valve 56p. Consequently, the controller 50 can position a predetermined point P, which was located at point Pa at the first time point, to point Pb at the second time point, and can position the predetermined point P to point Pc at the third time point. Similarly, the controller 50 can position the predetermined point P to point Pd at the fourth time point, and can position the predetermined point P to point Pe at the fifth time point. As a result, the controller 50 can position a predetermined point Q, which was located at point Qa at the first time point, to point Qb at the second time point, and can position the predetermined point Q to point Qc at the third time point. Similarly, the controller 50 can position the predetermined point Q to point Qd at the fourth time point, and can position the predetermined point Q to point Qe at the fifth time point.

[0103] In addition, such as Figure 4 As shown, when the asphalt roller 100 is equipped with a rudder angle sensor 58 for detecting rudder angle, the controller 50 can control the rudder angle based on the detection result of the rudder angle sensor 58 and the target value of the rudder angle.

[0104] And, as Figure 6 As shown, when the asphalt tumbler 100 is equipped with a steering angle sensor 59 for detecting the steering angle of the steering handle SH, the controller 50 can control the proportional control valve 56p based on the detection result of the steering angle sensor 59. Specifically, the controller 50 can obtain the operating direction and operating amount of the steering handle SH based on the detection result of the steering angle sensor 59, and output the control command corresponding to the operating direction and operating amount to the proportional control valve 56p of the automatic steering device 56.

[0105] exist Figure 7 In the example shown, the left rear screed 31L extends to the left so that its left end face aligns with the left boundary line LP of the road RD, and the right rear screed 31R extends to the right so that its right end face aligns with the right boundary line RP of the road RD. Then, the left end face of the left rear screed 31L moves to follow the left boundary line LP, and the right end face of the right rear screed 31R moves to follow the right boundary line RP. Therefore, by causing the tractor 1 to move forward so that the predetermined point P in the center of the tractor 1 follows the target track TPT, the controller 50 can make the width of the road RD match the width of the newly laid pavement NP.

[0106] The controller 50 can extend or retract the rear screed 31 during the movement of the asphalt tumbler 100. For example, if the left end face of the left rear screed 31L might detach from the left boundary line LP towards the inside of the road RD, the controller 50 can extend the left rear screed 31L to the left. Or, if the right end face of the right rear screed 31R might detach from the right boundary line RP towards the inside of the road RD, the controller 50 can extend the right rear screed 31R to the right.

[0107] Furthermore, in Figure 7 In the example shown, when the asphalt roller 100 travels on the curve of road RD, the steering control unit 50b controls the steering of the asphalt roller 100. However, when the asphalt roller 100 travels on the straight section of road RD, the steering control unit 50b can control the steering of the asphalt roller 100.

[0108] Next, refer to Figure 8 The function of moving the asphalt roller 100 while determining the target position in real time is explained. Figure 8 This is a top view showing the construction site of an asphalt roller 100 passing through the bend of road RD, which is the object under construction. For clarity, [the image is shown in the original text]. Figure 7 Similarly, Figure 8The diagram simplifies the asphalt roller 100, showing the tractor 1, the front leveler 30, the left rear leveler 31L, and the right rear leveler 31R. The hopper 2 is omitted from the illustration.

[0109] exist Figure 8 In the example shown, the target calculation unit 50a of the controller 50 derives the centerline CP of the road RD of the construction object based on the information obtained by the forward monitoring device 51F. Figure 8 In the example shown, the centerline CP is represented by a dotted line. Specifically, the target calculation unit 50a derives the left boundary line LP and right boundary line RP of the road RD based on the information obtained from the forward monitoring device 51F, and then derives the centerline CP of the road RD based on the left boundary line LP and right boundary line RP. The information obtained by the forward monitoring device 51F includes, for example, the position and orientation of the elevation difference between the curb and the roadbed BS. Furthermore, the target calculation unit 50a derives the current position Pn of a predetermined point P in the center of the tractor 1 and the current position Qn of a predetermined point Q in the center of the front leveler 30. Specifically, the target calculation unit 50a derives the current position Pn of the predetermined point P and the current position Qn of the predetermined point Q based on the output of the positioning device 51P. Figure 8 In the example shown, the predetermined point P is represented by “○” and the predetermined point Q is represented by “△”.

[0110] Then, the target calculation unit 50a calculates the target position Pf, which is the location that the predetermined point P needs to reach after a predetermined time. Specifically, the target calculation unit 50a calculates the target position Qf, the location that the predetermined point Q needs to reach after a predetermined time, based on the construction design data and the current position Pn of the predetermined point P. Furthermore, the target calculation unit 50a calculates the target position Pf based on known information, including the distance between the rear wheel 5 and the front wheel 6 of the asphalt roller 100, and the target position Qf. Both the target position Pf and the target position Qf are derived as position coordinates. The position coordinates are, for example, coordinates in a reference coordinate system. Figure 8 In the example shown, the target position Pf is represented by a dotted line “○”, and the target position Qf is represented by a dotted line “△”.

[0111] Then, the steering control unit 50b of the controller 50 causes the asphalt roller 100 to operate in a manner that makes the position coordinates of the predetermined point P consistent with the position coordinates of the target position Pf. For example, the steering control unit 50b derives the central axis AX of the asphalt roller 100 based on the output of the positioning device 51P.

[0112] Then, when the target position Pf is located to the left of the central axis AX, the steering control unit 50b outputs a control command to the proportional control valve 56p of the automatic steering device 56 constituting the steering device 53, increasing the rudder angle to the left. The proportional control valve 56p then moves the valve stem to the second position and adjusts the flow path of the working oil to a proportional opening to the control command, allowing a predetermined amount of working oil to flow from the hydraulic pump 55 into the left oil chamber of the steering cylinder 54. As a result, through the steering mechanism 7, the rudder angle of the left and right front wheels 6, 6 increases to the left, and the asphalt tumbler 100 moves forward while simultaneously moving to the left, bringing the predetermined point P closer to the target position Pf.

[0113] Conversely, when the target position Pf is located further to the right than the central axis AX, the steering control unit 50b outputs a control command to the proportional control valve 56p of the automatic steering device 56 constituting the steering device 53, increasing the rudder angle to the right. The proportional control valve 56p then moves the valve stem to position 3 and adjusts the flow path of the working oil to a proportional opening to the control command, allowing a predetermined amount of working oil to flow from the hydraulic pump 55 into the right oil chamber of the steering cylinder 54. As a result, through the steering mechanism 7, the rudder angle of the left and right front wheels 6, 6 increases to the right, and the asphalt tumbler 100 moves forward while simultaneously moving to the right, bringing the predetermined point P closer to the target position Pf.

[0114] Thus, controller 50 controls the rudder angle by controlling proportional control valve 56p. Consequently, controller 50 can position the predetermined point P to the target position Pf. As a result, controller 50 can position the predetermined point Q to the target position Qf.

[0115] The steering control unit 50b can operate the asphalt roller 100 in a manner that makes the position coordinates of the predetermined point Q consistent with the position coordinates of the target position Qf. Alternatively, the steering control unit 50b can operate the asphalt roller 100 in a manner that brings the predetermined point Q closer to the centerline CP of the road RD. In this case, the steering control unit 50b determines, according to a predetermined control cycle, whether the predetermined point Q is located on the centerline CP of the road RD, to the right of the centerline CP, or to the left of the centerline CP. Then, if it is determined to be located to the right, the steering control unit 50b moves the asphalt roller 100 to the left, and if it is determined to be located to the left, it moves the asphalt roller 100 to the right.

[0116] exist Figure 8In the example shown, the left rear screed 31L extends to the left so that its left end face aligns with the left boundary line LP of the road RD, and the right rear screed 31R extends to the right so that its right end face aligns with the right boundary line RP of the road RD. Then, the left end face of the left rear screed 31L moves in accordance with the left boundary line LP, and the right end face of the right rear screed 31R moves in accordance with the right boundary line RP. Therefore, by causing the tractor 1 to advance in a manner that causes the predetermined point P in the center of the tractor 1 to follow the target position Pf calculated according to a predetermined control cycle, the controller 50 can make the width of the road RD match the width of the newly laid pavement NP.

[0117] The controller 50 can extend or retract the rear screed 31 during the movement of the asphalt tumbler 100. For example, if the left end face of the left rear screed 31L might detach from the left boundary line LP towards the inside of the road RD, the controller 50 can extend the left rear screed 31L to the left. Or, if the right end face of the right rear screed 31R might detach from the right boundary line RP towards the inside of the road RD, the controller 50 can extend the right rear screed 31R to the right.

[0118] Furthermore, in Figure 8 In the example shown, when the asphalt roller 100 travels on the curve of road RD, the steering control unit 50b controls the steering of the asphalt roller 100. However, when the asphalt roller 100 travels on the straight section of road RD, the steering control unit 50b can control the steering of the asphalt roller 100.

[0119] Next, refer to Figure 9A and Figure 9B The effect of automatically controlling the asphalt roller 100 through the steering device 53 is explained. Figure 9A and Figure 9B This is a top view showing the construction site of an asphalt roller 100 passing through the bend of road RD, which is the object of construction. Specifically, Figure 9A The operation of the asphalt roller 100 is shown when the steering device 53 performs automatic steering. Figure 9B The operation of the asphalt trolley 100 during manual steering is shown, in which a predetermined point P in the center of the tractor 1 follows the centerline CP of the road RD. Figure 9A and Figure 9B In the example shown, the predetermined point P in the center of the tractor 1 is represented by “○”, and the predetermined point Q in the center of the front leveler 30 is represented by “△”.

[0120] like Figure 9BAs shown, if the machine is manually steered so that the predetermined point P follows the centerline CP of the road RD, the predetermined point Q in the center of the front screed 30 follows the trajectory PS, indicated by the double-dotted line. That is, when the asphalt roller 100 passes through the bend of the road RD, the distance between the front end of the right side of the tractor 1 and the right boundary line RP of the road RD changes to be approximately equal to the distance between the front end of the left side of the tractor 1 and the left boundary line LP of the road RD. However, the distance between the front end of the right side of the front screed 30 and the right boundary line RP of the road RD changes to be smaller than the distance between the front end of the left side of the front screed 30 and the left boundary line LP of the road RD. Therefore, paving material is not laid in the inner region of the bend of the road RD, as shown in the dot pattern, while paving material is laid beyond the right boundary line RP of the road RD in the outer region of the bend of the road RD, as shown in the grid pattern.

[0121] Thus, when the asphalt roller 100 passes through the bend of road RD, the operator of the asphalt roller 100 moves the asphalt roller 100 to center the tractor 1 in the width direction of road RD. However, even with this movement of the asphalt roller 100, it is impossible to position the leveler 3 in the width direction of road RD.

[0122] In contrast, such as Figure 7 and Figure 9A As shown, assuming the movement of the asphalt trolley 100 is automatically controlled by the steering device 53, so that the predetermined point P follows the target track TPT. Thus, the predetermined point Q in the central part of the front screed 30 follows the centerline CP of the road RD, shown as a dashed line. That is, when the asphalt trolley 100 passes through the bend of the road RD, the distance between the front end of the right side of the tractor 1 and the right boundary line RP of the road RD changes to a state where it is smaller than the distance between the front end of the left side of the tractor 1 and the left boundary line LP of the road RD. However, the distance between the front end of the right side of the front screed 30 and the right boundary line RP of the road RD changes to a state where it is approximately equal to the distance between the front end of the left side of the front screed 30 and the left boundary line LP of the road RD. Therefore, the paving material is reliably laid in the inner region of the bend of the road RD, and the paving material does not extend beyond the right boundary line RP of the road RD. That is, the asphalt roller 100 can make the width of the road RD and the width of the newly laid pavement NP consistent even in the curved part of the road RD.

[0123] Thus, when the asphalt roller 100 passes through the bend of the road RD, the controller 50 moves the asphalt roller 100 so that the tractor 1 is close to the end of the road RD in the width direction. Therefore, the leveler 3 can be positioned at the center of the road RD in the width direction.

[0124] As described above, the asphalt screed 100 according to the embodiments of this disclosure includes a traction machine 1, a hopper 2, a conveyor CV, a screw SC, a leveling machine 3, an information acquisition device 51, and a controller 50. The hopper 2 is located in front of the traction machine 1 and receives paving material. The conveyor CV transports the paving material in the hopper 2 to the rear of the traction machine 1. The screw SC spreads the paving material transported by the conveyor CV at the rear of the traction machine 1. The leveling machine 3 evenly spreads the paving material spread by the screw SC at the rear of the screw SC. The information acquisition device 51 acquires information related to the road being constructed. The controller 50 is a control device that controls the movement of the traction machine 1 based on a target track TPT or a target position Pf or Qf determined by the information acquisition device 51 related to the road being constructed.

[0125] According to this structure, the asphalt roller 100 can properly lay the pavement along the road RD of the construction object.

[0126] Furthermore, as described above, conventional construction machinery as described in Patent Document 1 uses a steering cylinder controlled by a signal from a controller to operate the steering wheel's direction switching valve. In the automated control of the asphalt trolley 100 of this embodiment, for example, the steering angle is sometimes increased or decreased to the left or right in control units that are finer than the manual operation of the steering handle SH, such as 0.1 degree units, 1 degree units, or several degrees.

[0127] The directional control valves in conventional construction machinery switch the flow path of the working oil between fully open and fully closed states to adjust the flow rate of the working oil. Therefore, if these directional control valves are used for automated control, the rudder angle resolution required for the automated control of this embodiment sometimes cannot be achieved. Thus, conventional construction machinery faces challenges in improving the accuracy of rudder angle control. Furthermore, because conventional construction machinery repeatedly performs these fine rudder angle controls, the opening and closing of the directional control valve becomes frequent, potentially increasing the burden on the valve.

[0128] In contrast, the asphalt roller 100 of this embodiment includes: a plurality of wheels W, including front wheels 6, 6 of a steering wheel; a steering cylinder 54 for adjusting the steering angle of the steering wheel; and a hydraulic pump 55 for supplying working oil to the steering cylinder 54. Furthermore, the asphalt roller 100 includes a proportional control valve 56p and a controller 50. The proportional control valve 56p is disposed between the hydraulic pump 55 and the steering cylinder 54, and controls the flow rate and direction of the working oil supplied to the steering cylinder 54. The controller 50 controls the steering angle by controlling the proportional control valve 56p.

[0129] According to this structure, the accuracy of the rudder angle control of the asphalt roller 100 can be improved. Specifically, in the automated control of the asphalt roller 100, the flow rate of the working oil supplied to the steering cylinder 54 can be proportionally controlled by the proportional control valve 56p according to the rudder angle control command from the controller 50. Therefore, the flow rate of the working oil supplied to the steering cylinder 54 can be finely controlled by the proportional control valve 56p, and the rudder angle can be controlled by the steering cylinder 54 in fine angular units. As a result, continuous steering and fine and smooth steering can be performed. Therefore, the asphalt roller 100 according to this embodiment can improve the accuracy of rudder angle control, thereby improving the accuracy of following the target path during automated control. Furthermore, in fine rudder angle control, the repeated opening and closing of the proportional control valve 56p can be suppressed, thereby reducing the burden on the proportional control valve 56p.

[0130] Furthermore, the asphalt trolley 100 according to this embodiment includes a steering handle SH for manual operation of the steering angle and a manual steering device 57 arranged in parallel with the proportional control valve 56p between the hydraulic pump 55 and the steering cylinder 54. The manual steering device 57 controls the flow rate and direction of the working oil supplied from the hydraulic pump 55 to the steering cylinder 54 according to the operation of the steering handle SH. The controller 50 closes the proportional control valve 56p to prioritize manual operation when the steering handle SH is operated.

[0131] According to this structure, not only is automated control of the rudder angle using the proportional control valve 56p possible, but manual operation is also possible, allowing the driver to change the rudder angle by operating the steering handle SH. Furthermore, the proportional control valve 56p and the manual steering device 57 are connected in parallel between the hydraulic pump 55 and the steering cylinder 54. This reduces pressure loss of the hydraulic oil supplied from the hydraulic pump 55 to the steering cylinder 54 compared to connecting these components in series. Furthermore, the influence of one of the proportional control valve 56p and the manual steering device 57 on the other is suppressed, thereby improving the redundancy of the steering system 53. And, as... Figure 6 As shown in the steering device 53A, the manual steering device 57 of the steering device 53 can be replaced with the steering angle sensor 59.

[0132] Specifically, such as Figure 6 As shown, the asphalt tumbler 100 may also include a steering handle SH for manual operation of the steering angle and a steering angle sensor 59 for detecting the steering angle of the steering handle SH. In this case, as described above, the controller 50 controls the proportional control valve 56p based on the detection result of the steering angle sensor 59.

[0133] This structure simplifies the device by eliminating the manual steering device 57, and improves the accuracy of the rudder angle control of the asphalt roller 100 in the automatic control of the rudder angle.

[0134] Furthermore, the asphalt roller 100 involved in this embodiment also includes a rudder angle sensor 58 for detecting the rudder angle, and the controller 50 controls the rudder angle based on the detection result of the rudder angle sensor 58 and the target value of the rudder angle.

[0135] Based on this structure, feedback control of the rudder angle can be performed, thereby further improving the accuracy of the rudder angle control of the asphalt tumbler 100.

[0136] like Figure 7 or Figure 8 As shown, the road RD of the construction object bends to the left. At this time, the controller 50 can be configured to set the target track TPT or the target position Pf outside (to the right) of the center (centerline CP) of the road RD of the construction object in the curved section. In addition, the target track TPT is, for example, the target track that a predetermined point P in the center of the traction machine 1 needs to follow, and the target position Pf is the location that the predetermined point P needs to reach after a predetermined time.

[0137] The controller 50 can be configured to set the target track TPT or target position Pf in a manner that aligns the width-direction center of the road RD of the construction object with the width-direction center of the leveling machine 3. For example, as Figure 7 As shown, the target calculation unit 50a of the controller 50 can be configured to set the target track TPT or target position Pf in such a way that the trajectory drawn by the predetermined point Q in the central part of the front leveling machine 30 is consistent with the center line CP of the road RD.

[0138] According to this structure, even when the asphalt roller 100 passes through both the straight and curved sections of the road RD, the controller 50 can make the width of the road RD consistent with the width of the newly laid pavement NP.

[0139] The controller 50 can be configured to set the target track TPT or target position Pf in such a way that at least one end of the leveling machine 3 is aligned with the ground surface. For example, as Figure 7As shown, the target calculation unit 50a of the controller 50 can set the target track TPT or target position Pf such that the left end of the leveling machine 3 is aligned with the left boundary line LP of the road RD and the right end of the leveling machine 3 is aligned with the right boundary line RP of the road RD. Alternatively, the target calculation unit 50a of the controller 50 can set the target track TPT or target position Pf such that the left end of the leveling machine 3 is aligned with the left boundary line LP of the road RD. Alternatively, the target calculation unit 50a of the controller 50 can set the target track TPT or target position Pf such that the right end of the leveling machine 3 is aligned with the right boundary line RP of the road RD.

[0140] Furthermore, the controller 50 can be configured to set the target track TPT or target position Pf based on the distance in the longitudinal direction between the predetermined point P, which serves as the steering reference point, and the leveler 3. For example, the controller 50 can be configured to set the target track TPT or target position Pf based on the distance in the longitudinal direction between the predetermined point P and the predetermined point Q in the center of the front leveler 30.

[0141] Furthermore, the controller 50 can be configured to set a target trajectory TPS or a target position Qf based on the longitudinal distance between a predetermined point P, which serves as a steering reference point, and the leveling machine 3. For example, the controller 50 can be configured to set the target trajectory TPS or the target position Qf based on the longitudinal distance between the predetermined point P and a predetermined point Q in the center of the front leveling machine 30. Additionally, the target trajectory TPS is, for example, the target trajectory that the predetermined point Q in the center of the front leveling machine 30 needs to follow, and the target position Qf is the location that the predetermined point Q needs to reach after a predetermined time has elapsed.

[0142] The controller 50 can be configured to control the movement of the traction machine 1 such that the asphalt roller 100 moves along a pre-set target track TPT. Specifically, the controller 50 can be configured to control the movement of the traction machine 1 such that the asphalt roller 100 moves along a target track TPT set before the asphalt roller 100 begins to move. However, the controller 50 can also be configured to control the movement of the traction machine 1 such that the asphalt roller 100 moves along a target track TPT calculated in real time.

[0143] According to this structure, the controller 50 can control the movement of the traction machine 1 simply, reliably and appropriately.

[0144] The information acquisition device 51 can be a camera device or a communication device 51T. Moreover, the camera device can be a LiDAR, a monocular camera, a stereo camera, or a depth camera, etc.

[0145] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Various modifications or substitutions can be applied to the above embodiments without departing from the scope of the present invention. Furthermore, the features described with reference to the above embodiments can be appropriately combined as long as they are not technically contradictory.

Claims

1. An asphalt rolling machine, comprising: Multiple wheels, including the steering wheel; Steering cylinder, used to adjust the rudder angle of the steering wheel; The hydraulic pump supplies working oil to the steering cylinder; A proportional control valve, disposed between the hydraulic pump and the steering cylinder, controls the flow rate and direction of the working oil supplied to the steering cylinder; and The controller controls the rudder angle by controlling the proportional control valve.

2. The asphalt roller according to claim 1, further comprising: A steering handle for manual operation of the rudder angle; and A manual steering device, arranged in parallel with the proportional control valve between the hydraulic pump and the steering cylinder, controls the flow rate and direction of the hydraulic oil supplied from the hydraulic pump to the steering cylinder based on the operation of the steering handle. The controller closes the proportional control valve to prioritize manual operation when the steering handle is operated.

3. The asphalt roller according to claim 1, further comprising: A steering handle for manual operation of the rudder angle; and The steering angle sensor detects the steering angle of the steering handle. The controller controls the proportional control valve based on the detection results of the steering angle sensor.

4. The asphalt roller according to claim 1, further comprising: The rudder angle sensor detects the rudder angle. The controller controls the rudder angle based on the detection results of the rudder angle sensor and the target value of the rudder angle.

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