Asphalt finisher

Abstract

To provide an asphalt finisher that improves construction quality of a road surface.SOLUTION: An asphalt finisher comprises a tractor, a hopper installed on the front side of the tractor, a conveyor that transports paving materials in the hopper to the rear side of the tractor, a screw that spreads, across the width of the vehicle, the paving materials transported by the conveyor and sprinkled on the road surface, and a screed device expandable in the width direction of the vehicle, the screed device spreading the paving materials sprinkled by the screw evenly on the rear side of the screw. The asphalt finisher is configured to change rotating speed of the screw on the basis of information about the moving direction of the asphalt finisher when asphalt finisher moves by the tractor.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an asphalt finisher.

Background Art

[0002] Conventionally, there is known an asphalt finisher including a tractor, a hopper installed on the front side of the tractor for receiving a paving material, a conveyor for feeding the paving material in the hopper to the rear side of the tractor, a screw for spreading the paving material fed by the conveyor on the rear side of the tractor, and a screed for leveling the paving material spread by the screw on the rear side of the screw.

[0003] When the asphalt finisher performs construction, control of the configuration of the asphalt finisher is performed according to the condition of the road surface on which the paving material is to be leveled. For example, in Patent Document 1, a technique for adjusting the rotation speed of the screw according to the expansion and contraction of the screed of the asphalt finisher has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In an asphalt finisher, by adjusting the rotation speed of the screw according to the expansion and contraction of the screed, the amount of the paving material held by the screed can be adjusted. Thereby, the paving material can be leveled on the road surface in an appropriate amount.

[0006] However, there are situations other than screed expansion and contraction where changing the screw rotation speed is necessary to adjust the amount of paving material the screed holds. For example, when an asphalt finisher changes direction along a road, the area of ​​the road surface being paved changes compared to when the asphalt finisher is moving in a straight line.

[0007] In light of the above, by changing the screw rotation speed according to the condition of the asphalt finisher, the appropriate amount of paving material can be spread according to the road surface, thereby improving the quality of road surface construction. [Means for solving the problem]

[0008] An asphalt finisher according to one aspect of the present invention comprises a tractor, a hopper installed on the front side of the tractor, and a conveyor that transports the paving material in the hopper to the rear side of the tractor. An asphalt finisher equipped with, It has a screw that spreads the paving material, which has been transported by a conveyor and scattered on the road surface, in the direction of the vehicle width, and a screed device that can extend and retract in the direction of the vehicle width and levels the paving material spread by the screw on the rear side of the screw, The screed device includes a right-side screed device located on the right side of the asphalt finisher and a left-side screed device located on the left side of the asphalt finisher. The screw includes a right screw and a left screw. The device further includes a storage unit that stores the speed of the asphalt finisher, the steering angle of the tractor, the length from the center position of the asphalt finisher in the vehicle width direction to the far end of each of the right-side and left-side screed devices, and the rotational speed of each of the right screw and left screw in association with each other. The device is further configured to detect the length by which each of the right-side and left-side screed devices extends or retracts in the vehicle width direction. The device is configured to change the rotational speed of each of the right screw and left screw based on the detection result from the detection unit, the storage unit, the acquired command value of the asphalt finisher speed, and the acquired command value of the tractor steering angle. [Effects of the Invention]

[0009] According to one aspect of the present invention, the quality of road surface construction is improved by achieving appropriate leveling according to the road surface by changing the rotation speed of the screw. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows an asphalt finisher, which is an example of road machinery according to the embodiment. [Figure 2] Figure 2 is a block diagram showing an example configuration of a controller and equipment connected to the controller according to this embodiment. [Figure 3] Figure 3 is an example of a table in the screw rotation speed storage unit according to the embodiment, which associates the current status of the asphalt finisher with the corresponding screw rotation speed. [Figure 4] Figure 4 is a hydraulic circuit diagram showing an example of the configuration of a hydraulic system mounted on an asphalt finisher according to the embodiment. [Figure 5] Figure 5 shows the configuration of the screw and screed in an asphalt finisher according to the embodiment. [Figure 6] Figure 6 is a diagram illustrating the length of the screed from the rear of the asphalt finisher according to the embodiment. [Figure 7] Figure 7 shows the target travel path based on the schedule information of the asphalt finisher according to the embodiment. [Figure 8] Figure 8 is a flowchart showing the control of an asphalt finisher by a controller according to this embodiment. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and their descriptions may be omitted.

[0012] Figure 1 is a schematic diagram of an asphalt finisher 100 according to an embodiment of the present invention. Specifically, Figure 1(A) is a left side view of the asphalt finisher 100, and Figure 1(B) is a top view of the asphalt finisher 100.

[0013] The asphalt finisher 100 mainly consists of a tractor 1, a hopper 2, and a screed 3. In the example shown in Figure 1, the asphalt finisher 100 is positioned so that the vehicle length direction corresponds to the X-axis direction and the vehicle width direction corresponds to the Y-axis direction. The Z-axis is positioned perpendicular to both the X-axis and the Y-axis. Specifically, the front side in the vehicle length direction corresponds to the +X side, the rear side in the vehicle length direction corresponds to the -X side, the left side in the vehicle width direction corresponds to the +Y side, the right side in the vehicle width direction corresponds to the -Y side, the upper side in the vertical direction corresponds to the +Z side, and the lower side in the vertical direction corresponds to the -Z side.

[0014] The tractor 1 is a mechanism for driving the asphalt finisher 100. In the example shown in FIG. 1, the tractor 1 rotates the rear wheels 5 using a rear-wheel drive motor 20 (see FIG. 4) and rotates the front wheels 6 using a front-wheel drive motor 22 (see FIG. 4), thereby moving the asphalt finisher 100. Both the rear-wheel drive motor 20 and the front-wheel drive motor 22 are hydraulic motors that rotate by receiving the supply of hydraulic oil from a hydraulic pump. However, the tractor 1 may be provided with crawlers instead of wheels.

[0015] The asphalt finisher 100 according to the present embodiment changes the traveling direction by controlling the steering angle of the front wheels 6. When the asphalt finisher 100 is provided with crawlers instead of wheels, the traveling direction is changed by making the rotational speeds of the drive wheels in the right crawler and the drive wheels in the left crawler different.

[0016] The hopper 2 is a mechanism for receiving paving materials. The paving materials are, for example, asphalt mixtures and the like. In the example shown in FIG. 1, the hopper 2 is installed on the front side (+X side) of the tractor 1 and is configured to be opened and closed in the Y-axis direction (vehicle width direction) by a hopper cylinder 24. The asphalt finisher 100 usually receives paving materials from the cargo bed of a dump truck with the hopper 2 fully open. Also, when the asphalt finisher 100 is receiving paving materials from the cargo bed of a dump truck, it continues to travel while pushing the dump truck forward via a push roller 2b. FIGS. 1(A) and 1(B) show the asphalt finisher 100 when the hopper 2 is fully open. When the paving materials in the hopper 2 decrease, the operator of the asphalt finisher 100 closes the hopper 2 to collect the paving materials near the inner wall of the hopper 2 at the central part of the hopper 2. This is to enable the conveyor CV at the bottom of the central part of the hopper 2 to convey the paving materials to the rear side of the tractor 1. The paving materials conveyed to the rear side (-X side) of the tractor 1 are spread in the vehicle width direction behind the tractor 1 and in front of the screed 3 by a screw SC.

[0017] The conveyor CV is driven by a hydraulic motor that rotates upon receiving the supply of hydraulic oil from a hydraulic pump. In the example shown in FIG. 1, the conveyor CV is configured to send the paving material in the hopper 2 to the rear side of the tractor 1 via the conveying passage CP. The conveying passage CP is a substantially rectangular parallelepiped-shaped space formed inside the tractor 1 and has a substantially rectangular inlet OP that opens into the hopper 2 on the front surface of the tractor 1. Specifically, the conveyor CV includes a left conveyor and a right conveyor.

[0018] The screw SC is driven by a hydraulic motor that rotates upon receiving the supply of hydraulic oil from a hydraulic pump. Specifically, the screw SC includes a left screw SCL provided on the left side of the asphalt finisher 100 and a right screw SCR provided on the right side of the asphalt finisher 100. The left conveyor is configured to send the paving material toward the left screw SCL. The right conveyor is configured to send the paving material toward the right screw SCR. The left screw SCL and the right screw SCR are arranged within the width of the tractor 1.

[0019] The screed 3 is a mechanism for leveling the paving material. In the example shown in FIG. 1, the screed 3 mainly includes a main screed 30 and a telescopic screed 31. The main screed 30 includes a left main screed and a right main screed. The telescopic screed 31 includes a left telescopic screed 31L and a right telescopic screed 31R. The main screed 30, the left telescopic screed 31L, and the right telescopic screed 31R are arranged offset front and back so as not to overlap in the vehicle length direction. Specifically, the left telescopic screed 31L is arranged behind the main screed 30, and the right telescopic screed 31R is arranged behind the left telescopic screed 31L. The screed 3 is a floating screed towed by the tractor 1 and is connected to the tractor 1 via a leveling arm 3A. The screed 3 is moved up and down together with the leveling arm 3A by the extension and retraction of the screed lift cylinder 25. The leveling arm 3A includes a left leveling arm 3AL and a right leveling arm 3AR.

[0020] The retractable screed 31 is configured to be extendable and retractable in the vehicle width direction by a screed retractable cylinder 27. The screed retractable cylinder 27 is supported by a support fixed to the rear surface of the housing of the main screed 30, and is configured to extend and retract the retractable screed 31 in the vehicle width direction (Y-axis direction). Specifically, the screed retractable cylinder 27 includes a left screed retractable cylinder 27L (an example of a left-side screed device) and a right screed retractable cylinder 27R (an example of a right-side screed device). The left screed retractable cylinder 27L can extend and retract the left retractable screed 31L to the left side in the vehicle width direction relative to the main screed 30. The right screed retractable cylinder 27R can extend and retract the right retractable screed 31R to the right side in the vehicle width direction relative to the main screed 30.

[0021] The leveling arm 3A is configured to connect the screed 3 to the tractor 1. Specifically, one end of the leveling arm 3A is connected to the screed 3, and the other end is rotatably connected to the tractor 1.

[0022] The leveling cylinder 23 is a hydraulic cylinder that moves the front end portion of the leveling arm 3A up and down to adjust the paving thickness. In the example shown in Figure 1, the leveling cylinder 23 has a cylinder portion connected to the tractor 1 and a rod portion connected to the front end portion of the leveling arm 3A. The front end portion of the leveling arm 3A is slidably supported by the tractor 1. To increase the paving thickness, the controller 50 causes the hydraulic fluid discharged by the hydraulic pump to flow into the rod-side oil chamber of the leveling cylinder 23, causing the leveling cylinder 23 to contract and raise the front end portion of the leveling arm 3A. On the other hand, to decrease the paving thickness, the controller 50 causes the hydraulic fluid to flow out of the rod-side oil chamber of the leveling cylinder 23, causing the leveling cylinder 23 to extend and lower the front end portion of the leveling arm 3A.

[0023] The screed lift cylinder 25 is a hydraulic cylinder used to lift the screed 3. In the example shown in Figure 1, the screed lift cylinder 25 has its cylinder section connected to the tractor 1 and its rod section connected to the rear end of the leveling arm 3A. When lifting the screed 3, the controller 50 allows the hydraulic fluid discharged by the hydraulic pump to flow into the rod-side oil chamber of the screed lift cylinder 25. As a result, the screed lift cylinder 25 contracts, the rear end of the leveling arm 3A lifts, and the screed 3 is lifted. On the other hand, when lowering the lifted screed 3, the controller 50 allows the hydraulic fluid in the rod-side oil chamber of the screed lift cylinder 25 to flow out. As a result, the screed lift cylinder 25 extends due to the weight of the screed 3, the rear end of the leveling arm 3A lowers, and the screed 3 is lowered.

[0024] A side plate 40 is attached to the distal end of the telescopic screed 31. The side plate 40 includes a left side plate 40L and a right side plate 40R. Specifically, the left side plate 40L is attached to the distal end (left end) of the left telescopic screed 31L, and the right side plate 40R is attached to the distal end (right end) of the right telescopic screed 31R.

[0025] As shown in Figure 1(B), the side plate 40 extends its front end in the direction of travel (positive X-axis direction) to the extension of the longitudinal direction (rotation axis direction) of the screw SC.

[0026] The side plate 40 is also attached to the distal end of the expandable mold board 41. The expandable mold board 41 is a component for adjusting the amount of paving material that remains in front of the expandable screed 31 among the paving material spread by the screw SC, and is configured to expand and contract in the vehicle width direction together with the expandable screed 31.

[0027] Specifically, the expandable molded board 41 is a plate-shaped member that extends in the vehicle width direction, and includes a left expandable molded board 41L and a right expandable molded board 41R. A left side plate 40L (an example of a plate portion) is attached to the distal end (left end) of the left expandable molded board 41L, and a right side plate 40R (an example of a plate portion) is attached to the distal end (right end) of the right expandable molded board 41R.

[0028] The expandable mold board 41 is configured to allow height adjustment in the Z-axis direction independently of the expandable screed 31 and side plates 40. The asphalt finisher 100 can adjust the amount of paving material passing through the gap by moving the expandable mold board 41 up and down, thereby adjusting the size of the gap between the lower end of the expandable mold board 41 and the roadbed. Therefore, the asphalt finisher 100 can adjust the amount (height) of paving material that accumulates on the rear side (-X side) of the expandable mold board 41 and on the front side (+X side) of the expandable screed 31 by moving the expandable mold board 41 up and down, and consequently adjust the amount of paving material taken into the underside of the expandable screed 31.

[0029] The screed step 42 is a component that constitutes a platform for workers when working behind the screed 3. Specifically, the screed step 42 includes the left screed step 42L, the center screed step 42C, and the right screed step 42R.

[0030] The retaining plate 43 is a plate-shaped member that prevents the paving material being fed in the width direction by the screw SC from scattering in front of the screw SC, in order to ensure that the paving material is properly fed in the width direction by the screw SC. In the example shown in Figure 1, the retaining plate 43 includes a left retaining plate 43L and a right retaining plate 43R.

[0031] The controller 50 is a control device that controls the asphalt finisher 100. In the example shown in Figure 1, the controller 50 is a computer including a CPU, a volatile memory device, and a non-volatile memory device, and is mounted on the tractor 1. Various functions of the controller 50 are realized, for example, by the CPU executing a program stored in the non-volatile memory device. The various functions realized by the controller 50 also include, for example, a function to control the discharge amount of the hydraulic pump that supplies hydraulic fluid to drive the hydraulic actuator, and a function to control the flow of hydraulic fluid between the hydraulic actuator and the hydraulic pump. The hydraulic actuator includes a hydraulic cylinder and a hydraulic motor.

[0032] The communication device 53 is configured to control communication between the asphalt finisher 100 and equipment located outside the asphalt finisher 100. In this embodiment, the communication device 53 is installed in front of the driver's seat 1S and controls communication via a mobile phone network, a short-range wireless communication network, or a satellite communication network.

[0033] The GPS module 54 is an example of a GNSS (Global Navigation Satellite System) module and receives location information representing the results of two-dimensional positioning (two-dimensional positioning) by GPS (Global Positioning System). The location information includes information representing the position of the asphalt finisher 100 in terms of latitude and longitude. In this embodiment, GPS is used as the method for acquiring location information, but the method for acquiring location information is not limited, and other well-known methods may be used.

[0034] A spatial recognition device 51 is attached to the tractor 1. The spatial recognition device 51 is configured to acquire information about the space around the asphalt finisher 100 and to output the acquired information to the controller 50. The spatial recognition device 51 according to this embodiment includes a forward monitoring device 51F, a rear monitoring device 51B, a right-side monitoring device 51R, and a left-side monitoring device 51L.

[0035] The forward monitoring device 51F is configured to monitor the area in front of the asphalt finisher 100. In this embodiment, the forward monitoring device 51F is a LIDAR whose monitoring range RF is the space in front of the tractor 1, and is mounted on the front center of the upper surface of the tractor 1. The forward monitoring device 51F may also be mounted on other parts of the asphalt finisher 100.

[0036] The rear monitoring device 51B is configured to monitor the area behind the asphalt paver 100. In this embodiment, the rear monitoring device 51B is a LIDAR with a monitoring range RB of the space behind the screed 3, and is mounted on the guide rail 1G, which functions as a handrail for the operator of the asphalt paver 100. The rear monitoring device 51B may also be mounted under the driver's seat 1S, or on other parts of the asphalt paver 100.

[0037] The right-side monitoring device 51R is configured to monitor the right side of the asphalt paver 100. The left-side monitoring device 51L is configured to monitor the left side of the asphalt paver 100. In this embodiment, the right-side monitoring device 51R and the left-side monitoring device 51L are configured to include the edge of the road surface (the boundary between the road surface and the shoulder) and the side plate 40 provided at the distal end of the telescopic screed 31 as part of their monitoring range. The right-side monitoring device 51R and the left-side monitoring device 51L are, for example, LIDARs and are mounted on the guide rail 1G which functions as a handrail for the operator of the asphalt paver 100. The right-side monitoring device 51R and the left-side monitoring device 51L may be mounted at any position on the side of the asphalt paver 100, provided that they include the monitoring range described above.

[0038] For example, the LIDAR measures the distance between the LIDAR and more than one million points within the monitoring range. However, at least one of the forward monitoring device 51F and the rear monitoring device 51B may be a monocular camera, stereo camera, millimeter-wave radar, laser radar, laser scanner, distance image camera, or laser rangefinder, etc. The same applies to the side monitoring device. This embodiment describes an example in which LIDAR is used as an example of a spatial recognition device 51. However, this embodiment does not limit the spatial recognition device 51 to LIDAR. In other words, any spatial recognition device capable of recognizing space with respect to the asphalt finisher 100 is acceptable.

[0039] The monitoring range RF of the forward monitoring device 51F includes the roadbed. The same applies to the monitoring range of the side monitoring device. In this embodiment, the monitoring range RF has a width greater than the width of the roadbed BS.

[0040] The monitoring range RB of the rearward monitoring device 51B includes the newly constructed pavement. In this embodiment, the monitoring range RB has a width greater than the width of the newly constructed pavement.

[0041] The measurement information detected by the spatial recognition device 51 according to this embodiment is transmitted to the controller 50. Based on the received measurement information, the controller 50 automatically steers the asphalt finisher 100. The controller 50 may also provide notifications such as warnings to the driver based on the received measurement information.

[0042] Next, with reference to Figure 2, the controller 50 mounted on the asphalt finisher 100 will be described. Figure 2 is a block diagram showing an example configuration of the controller 50 and the equipment connected to the controller 50.

[0043] As shown in Figure 2, the controller 50 is connected to a driving speed sensor 47, an auxiliary storage device 48, a GPS module 54, a forward monitoring device 51F, a rear monitoring device 51B, a drive system controller 52, a communication device 53, a screed control device 55, a screw control device 56, and a screed length detection device 57.

[0044] The travel speed sensor 47 is configured to detect the travel speed of the asphalt finisher 100. In the example shown in Figure 2, the travel speed sensor 47 is an encoder that detects the angular velocity of the rotation shaft of the rear wheel drive motor 20 that drives the rear wheels 5. Specifically, the travel speed sensor 47 includes a left travel speed sensor and a right travel speed sensor. The left travel speed sensor is an encoder that detects the angular velocity of the rotation shaft of the left rear wheel drive motor 20L that drives the left rear wheel. The right travel speed sensor is an encoder that detects the angular velocity of the rotation shaft of the right rear wheel drive motor 20R that drives the right rear wheel. The travel speed sensor 47 may also be configured as a proximity switch or the like that detects a slit formed in the rotating plate.

[0045] The auxiliary storage device 48 is configured to store various types of information. In the example shown in Figure 2, the auxiliary storage device 48 is a non-volatile storage device mounted on the tractor 1 and stores various types of information. For example, the auxiliary storage device 48 stores a schedule information storage unit 48a, a vehicle width storage unit 48b, and a screw rotation speed storage unit 48c.

[0046] The schedule information storage unit 48a stores schedule information for the asphalt finisher 100 to construct the road surface to be paved. The schedule information according to this embodiment includes, for example, the center line of the path the asphalt finisher 100 will travel and a target line indicating the edge of the road surface to be paved (the part that forms the boundary between the road surface and the shoulder). The asphalt finisher 100 according to this embodiment performs automatic control of road paving based on the schedule information.

[0047] The vehicle width memory unit 48b stores information on the length from the structural center position of the asphalt finisher 100 (in other words, the length from the left side to the right side of the asphalt finisher 100 in the vehicle width direction) to the side of the asphalt finisher 100.

[0048] Therefore, the controller 50 can calculate the distance from the center position in the vehicle width direction of the asphalt finisher 100 to the side plate 40, according to the length of the retractable screed 31 in the vehicle width direction.

[0049] The screw rotation speed memory unit 48c stores information on the rotation speed of the screw SC according to the current status of the asphalt finisher 100.

[0050] Figure 3 is an example of a table in the screw rotation speed storage unit 48c according to this embodiment, which associates the current status of the asphalt finisher 100 with the rotation speed of the screw SC corresponding to that status. In the example shown in Figure 3, the current status of the asphalt finisher 100 is associated with the rotation speed of the screw SC, which includes the speed of the asphalt finisher 100, the steering angle, and the length from the center position of the asphalt finisher 100 in the vehicle width direction to the far end of the telescopic screed 31. This table may be common to both the left screw SCL and the right screw SCR. For example, in the case of the right screw SCR, a record with a positive steering angle is referenced when turning right, and a record with a negative steering angle is referenced when turning left. In the case of the left screw SCL, a record with a negative steering angle is referenced when turning right, and a record with a positive steering angle is referenced when turning left. Alternatively, a separate table may be maintained for each of the left screw SCL and the right screw SCR.

[0051] In this embodiment, the table should include at least the steering angle of the asphalt finisher 100 as the current status of the asphalt finisher 100, corresponding to the rotational speed of the screw SC. This allows the rotational speed of the screw SC to be changed according to the steering angle of the asphalt finisher 100.

[0052] Returning to Figure 2, the GPS module 54 is an example of a GNSS (Global Navigation Satellite System) module and receives position information representing the result of two-dimensional positioning by GPS (Global Positioning System). The position information includes information representing the position of the asphalt finisher 100 in terms of latitude and longitude. In this embodiment, GPS is used as the method for acquiring position information, but the method for acquiring position information is not limited, and other well-known methods may be used.

[0053] The screed length detection device 57 (an example of a detection unit) detects the length by which the left retractable screed 31L and the right retractable screed 31R are extended or retracted in the vehicle width direction. The screed length detection device 57 may use any sensor that can detect the length by which the retractable screed 31 is extended or retracted in the vehicle width direction. The screed length detection device 57 may be a laser sensor or the like for detecting the said length, or it may be a GNSS module provided on the side plate 40. For example, the length by which the retractable screed 31 is extended or retracted in the vehicle width direction may be calculated from the distance between the position information detected by the GNSS module and the position information of the GNSS module provided on the main body of the asphalt finisher 100. As another example, instead of the screed length detection device 57, the controller 50 may determine the length of the retractable screed 31 in the vehicle width direction based on the measurement information of the right-side monitoring device 51R and the left-side monitoring device 51L, respectively.

[0054] The communication device 53 communicates wirelessly with devices located around the asphalt finisher 100, or with a server that manages the work site. In this embodiment, one or more of the following wireless communication standards may be used for the communication device 53: for example, Wi-Fi®, wireless LAN, and Bluetooth®.

[0055] The drive system controller 52 controls the tractor 1 according to control commands. For example, the drive system controller 52 controls the speed and steering angle of the tractor 1.

[0056] The screed control device 55 is configured to control the amount of extension and retraction of the retractable screed 31. In the example shown in Figure 2, the screed control device 55 controls the flow rate of hydraulic fluid into the screed extension cylinder 27. The screed control device 55 includes a screed extension control valve 37 shown in Figure 4, which switches the connection between the pipe connecting the rod-side oil chamber of the screed extension cylinder 27 and the hydraulic pump in response to a control command from the controller 50.

[0057] Then, the screed control device 55 performs the following actions in accordance with the control commands from the controller 50: contracting the left screed extension cylinder 27L to shorten the left extension screed 31L, and extending the left screed extension cylinder 27L to lengthen the left extension screed 31L.

[0058] Furthermore, the screed control device 55 performs the following actions in accordance with the control commands from the controller 50: contracting the right screed extension cylinder 27R to shorten the right extension screed 31R, and extending the right screed extension cylinder 27R to lengthen the right extension screed 31R.

[0059] In this manner, the screed control device 55 controls the lengths of the right retractable screed 31R and the left retractable screed 31L, respectively, according to the control commands from the controller 50.

[0060] The screw control device 56 is configured to control the rotational speed of the screw SC. In the example shown in Figure 2, the screw control device 56 is a solenoid valve that controls the flow rate of hydraulic fluid flowing into the hydraulic motor that drives the screw SC. Specifically, the screw control device 56 increases or decreases the flow path area of ​​the pipeline connecting the hydraulic motor that drives the screw SC and the hydraulic pump in response to a control command from the controller 50. More specifically, the screw control device 56 increases the flow rate of hydraulic fluid flowing into the hydraulic motor that drives the screw SC by increasing the flow path area, thereby increasing the rotational speed of the screw SC. Alternatively, the screw control device 56 decreases the flow rate of hydraulic fluid flowing into the hydraulic motor that drives the screw SC by decreasing the flow path area, thereby decreasing the rotational speed of the screw SC. In this embodiment, the screw control device 56 can change the rotational speed of the left screw SCL and the right screw SCR, respectively.

[0061] The controller 50 acquires information from the GPS module 54, the forward monitoring device 51F, the rear monitoring device 51B, the right-side monitoring device 51R, the left-side monitoring device 51L, the driving speed sensor 47, the screed length detection device 57, and the auxiliary storage device 48, performs various calculations, and then outputs control commands to the screed control device 55, the screw control device 56, and the drive system controller 52 according to the calculation results. The functional blocks of the controller 50 according to this embodiment will be described later.

[0062] <Explanation of the hydraulic system> Next, with reference to Figure 4, the hydraulic system installed in the asphalt finisher 100 will be described. Figure 4 is a hydraulic circuit diagram showing an example configuration of the hydraulic system installed in the asphalt finisher 100.

[0063] The hydraulic system mainly includes a hydraulic power source 14, a rear wheel drive unit F1, a conveyor screw drive unit F2, a front wheel drive unit F3, a steering and compaction device drive unit F4, a leveling unit F5, a hopper drive unit F6, a screed lift unit F7, and a screed extension / retraction unit F8.

[0064] The hydraulic power source 14 is configured to supply hydraulic fluid to operate various drive units. In this embodiment, the hydraulic power source 14 mainly includes an engine 14E, a rear wheel drive pump 14R, a charge pump 14C, a cylinder pump 14M, a conveyor screw pump 14S, and a front wheel drive pump 14F.

[0065] Engine 14E is the power source that drives the rear wheel drive pump 14R, charge pump 14C, cylinder pump 14M, conveyor screw pump 14S, and front wheel drive pump 14F.

[0066] The rear-wheel drive pump 14R is a variable displacement hydraulic pump that supplies hydraulic fluid for driving to the rear-wheel drive unit F1. In this embodiment, the rear-wheel drive pump 14R is a swashplate type variable displacement bidirectional hydraulic pump used in a closed circuit.

[0067] The charge pump 14C is a fixed-displacement hydraulic pump that supplies control fluid to the rear-wheel drive unit F1.

[0068] The cylinder pump 14M is a variable displacement hydraulic pump capable of supplying hydraulic fluid to the steering and compaction device drive unit F4, the leveling unit F5, the hopper drive unit F6, the screed lift unit F7, and the screed extension / retraction unit F8. In this embodiment, the cylinder pump 14M is a swashplate type variable displacement hydraulic pump, and its discharge volume is controlled so that the discharge pressure remains constant at a predetermined pressure.

[0069] The conveyor screw pump 14S is a variable displacement hydraulic pump that supplies hydraulic fluid to the conveyor screw drive unit F2. In this embodiment, the conveyor screw pump 14S is a swashplate type variable displacement hydraulic pump.

[0070] The front wheel drive pump 14F is a variable displacement hydraulic pump that supplies hydraulic fluid to the front wheel drive unit F3. In this embodiment, the front wheel drive pump 14F is a swashplate type variable displacement hydraulic pump.

[0071] The rear-wheel drive unit F1 is configured to drive the rear wheels 5. In this embodiment, the rear-wheel drive unit F1 includes a left rear-wheel drive motor 20L, a right rear-wheel drive motor 20R, check valves 20La and 20Ra, relief valves 20Lb and 20Rb, and a gearbox switching valve V0.

[0072] The left rear wheel drive motor 20L is a hydraulic motor that drives the left rear wheel. The right rear wheel drive motor 20R is a hydraulic motor that drives the right rear wheel. In this embodiment, the left rear wheel drive motor 20L and the right rear wheel drive motor 20R are continuously variable speed hydraulic motors and together with the rear wheel drive pump 14R, they form a closed circuit (HST circuit).

[0073] The check valve 20La maintains the hydraulic fluid pressure in the pipeline C1 connecting the first port of the rear wheel drive pump 14R to the second ports of the left rear wheel drive motor 20L and the right rear wheel drive motor 20R at or above a predetermined pressure. Specifically, the check valve 20La allows the hydraulic fluid discharged by the charge pump 14C to flow into pipeline C1 when the hydraulic fluid pressure in pipeline C1 falls below the discharge pressure of the charge pump 14C. The numbers in parentheses in the figure represent port numbers. Similarly, the check valve 20Ra maintains the hydraulic fluid pressure in the pipeline C2 connecting the second port of the rear wheel drive pump 14R to the first ports of the left rear wheel drive motor 20L and the right rear wheel drive motor 20R at or above a predetermined pressure. Specifically, the check valve 20Ra allows the hydraulic fluid discharged by the charge pump 14C to flow into pipeline C2 when the hydraulic fluid pressure in pipeline C2 falls below the discharge pressure of the charge pump 14C.

[0074] The relief valve 20Lb maintains the hydraulic fluid pressure in pipeline C1 below a predetermined relief pressure. Specifically, the relief valve 20Lb releases the hydraulic fluid from pipeline C1 to the outside of the closed circuit if the hydraulic fluid pressure in pipeline C1 exceeds the relief pressure. Similarly, the relief valve 20Rb maintains the hydraulic fluid pressure in pipeline C2 below a predetermined relief pressure. Specifically, the relief valve 20Rb releases the hydraulic fluid from pipeline C2 to the outside of the closed circuit if the hydraulic fluid pressure in pipeline C2 exceeds the relief pressure.

[0075] The gearbox switching valve V0 is a mechanism that switches the reduction ratios of the left rear wheel drive motor 20L and the right rear wheel drive motor 20R, respectively. In this embodiment, the gearbox switching valve V0 switches the reduction ratios of the left rear wheel drive motor 20L and the right rear wheel drive motor 20R, respectively, using the hydraulic fluid discharged by the charge pump 14C in response to a control command from the controller 50.

[0076] The conveyor screw drive unit F2 is configured to drive the conveyor CV and the screw SC. In this embodiment, the conveyor screw drive unit F2 mainly includes a conveyor motor 21C, a screw motor 21S, a conveyor control valve V1C, and a screw control valve V1S.

[0077] Both the conveyor motor 21C and the screw motor 21S are variable displacement hydraulic motors that form an open circuit. The conveyor motor 21C includes the left conveyor motor 21CL and the right conveyor motor 21CR. The screw motor 21S includes the left screw motor 21SL and the right screw motor 21SR. The conveyor control valve V1C includes the left conveyor control valve V1CL and the right conveyor control valve V1CR. The screw control valve V1S includes the left screw control valve V1SL and the right screw control valve V1SR.

[0078] The control valve V1CL for the left conveyor operates in response to a control command from the controller 50, allowing the hydraulic oil discharged by the conveyor screw pump 14S to flow into the suction port of the left conveyor motor 21CL, and discharging the hydraulic oil flowing out of the discharge port of the left conveyor motor 21CL into the hydraulic oil tank T. The control valve V1CR for the right conveyor operates in response to a control command from the controller 50, allowing the hydraulic oil discharged by the conveyor screw pump 14S to flow into the suction port of the right conveyor motor 21CR, and discharging the hydraulic oil flowing out of the discharge port of the right conveyor motor 21CR into the hydraulic oil tank T. Similarly, the control valve V1SL for the left screw operates in response to a control command from the controller 50, allowing the hydraulic oil discharged by the conveyor screw pump 14S to flow into the suction port of the left screw motor 21SL, and discharging the hydraulic oil flowing out of the discharge port of the left screw motor 21SL into the hydraulic oil tank T. The control valve V1SR for the right screw operates in response to a control command from the controller 50, directing the hydraulic fluid discharged by the conveyor screw pump 14S into the suction port of the right screw motor 21SR, and discharging the hydraulic fluid flowing out of the discharge port of the right screw motor 21SR into the hydraulic fluid tank T. The hydraulic fluid flowing out of the discharge ports of the left conveyor motor 21CL, the right conveyor motor 21CR, the left screw motor 21SL, and the right screw motor 21SR is discharged into the hydraulic fluid tank T through the oil cooler OC.

[0079] The front-wheel drive unit F3 is configured to drive the front wheels 6. In this embodiment, the front-wheel drive unit F3 mainly includes a front-wheel drive motor 22 and a front-wheel drive valve V2.

[0080] The front wheel drive motor 22 is a fixed-displacement hydraulic motor that forms an open circuit. The front wheel drive valve V2 operates in response to a control command from the controller 50, and allows the hydraulic fluid discharged by the front wheel drive pump 14F to flow into the suction port of the front wheel drive motor 22. In the example shown in Figure 4, the front wheel drive motor 22 includes a left front wheel drive motor 22L and a right front wheel drive motor 22R. The front wheel drive pump 14F supplies hydraulic fluid to the left front wheel drive motor 22L and the right front wheel drive motor 22R in parallel.

[0081] The steering and compaction device drive unit F4 is configured to drive the steering device and the compaction device (neither of which are shown). The steering device is a hydraulic device for steering the front wheels 6. In this embodiment, the steering device changes the steering angle of the front wheels 6 using hydraulic fluid discharged by the cylinder pump 14M in response to the operation of the steering wheel by the operator, for example. The compaction device is a hydraulic device for compacting the pavement material. In this embodiment, the compaction device includes a tamper and a vibrator, and the tamper and vibrator are operated using hydraulic fluid discharged by the cylinder pump 14M.

[0082] The leveling section F5 is configured to allow adjustment of the pavement thickness. In this embodiment, the leveling section F5 mainly includes a leveling cylinder 23, a leveling control valve 33, and a pilot check valve 33P.

[0083] The leveling cylinder 23 is a hydraulic cylinder that moves the leveling arm 3A up and down to adjust the pavement thickness. The leveling cylinder 23 is configured to contract when increasing the pavement thickness and to extend when decreasing the pavement thickness. In the example shown in Figure 4, the leveling cylinder 23 includes a left leveling cylinder 23L and a right leveling cylinder 23R.

[0084] The leveling control valve 33 is configured to operate in response to a control signal from the controller 50. In the example shown in Figure 4, the leveling control valve 33 includes a left leveling control valve 33L and a right leveling control valve 33R. When increasing the pavement thickness, the left leveling control valve 33L causes the hydraulic fluid discharged by the cylinder pump 14M to flow into the rod-side oil chamber of the left leveling cylinder 23L, and also causes the hydraulic fluid flowing out from the head-side oil chamber of the left leveling cylinder 23L to be discharged into the hydraulic fluid tank T. In this case, the left leveling cylinder 23L retracts, and the left leveling arm 3AL rises. The same applies to the right leveling control valve 33R, which retracts the right leveling cylinder 23R. On the other hand, when reducing the pavement thickness, the left leveling control valve 33L directs the hydraulic fluid discharged by the cylinder pump 14M into the head-side oil chamber of the left leveling cylinder 23L, and also discharges the hydraulic fluid flowing out of the rod-side oil chamber of the left leveling cylinder 23L into the hydraulic fluid tank T. In this case, the left leveling cylinder 23L extends, and the left leveling arm 3AL descends. The same applies to the right leveling control valve 33R, which extends the right leveling cylinder 23R.

[0085] The pilot check valve 33P is configured to prevent the leveling cylinder 23 from moving due to external force. In the example shown in Figure 4, the pilot check valve 33P includes pilot check valves 33PaL, 33PbL, 33PaR, and 33PbR. For example, the pilot check valve 33PaL allows the hydraulic fluid in the rod-side oil chamber of the left leveling cylinder 23L to flow toward the hydraulic fluid tank T only when the left leveling control valve 33L operates in response to the operator's operation and the hydraulic fluid discharged by the cylinder pump 14M flows into the head-side oil chamber of the left leveling cylinder 23L. In all other cases, the pilot check valve 33PaL prohibits the hydraulic fluid in the rod-side oil chamber of the left leveling cylinder 23L from flowing toward the hydraulic fluid tank T. The same applies to the pilot check valves 33PbL, 33PaR, and 33PbR.

[0086] The hopper drive unit F6 is configured to open and close the hopper 2. In this embodiment, the hopper drive unit F6 mainly includes a hopper cylinder 24, a hopper control valve 34, and a pilot check valve 34P.

[0087] The hopper cylinder 24 is a hydraulic actuator that opens and closes the hopper 2. It retracts when opening the hopper 2 and extends when closing the hopper 2. In the example shown in Figure 4, the hopper cylinder 24 includes a left hopper cylinder 24L and a right hopper cylinder 24R.

[0088] The hopper control valve 34 is configured to operate in response to a control signal from the controller 50. In the example shown in Figure 4, the hopper control valve 34 includes a left hopper control valve 34L and a right hopper control valve 34R. When hopper 2 is opened, the left hopper control valve 34L allows the hydraulic fluid discharged by the cylinder pump 14M to flow into the rod-side oil chamber of the left hopper cylinder 24L, and discharges the hydraulic fluid flowing out of the head-side oil chamber of the left hopper cylinder 24L into the hydraulic fluid tank T. In this case, the left hopper cylinder 24L retracts. The right hopper control valve 34R allows the hydraulic fluid discharged by the cylinder pump 14M to flow into the rod-side oil chamber of the right hopper cylinder 24R, and discharges the hydraulic fluid flowing out of the head-side oil chamber of the right hopper cylinder 24R into the hydraulic fluid tank T. In this case, the right hopper cylinder 24R retracts. On the other hand, when hopper 2 is closed, the control valve 34L for the left hopper allows the hydraulic fluid discharged by the cylinder pump 14M to flow into the head-side oil chamber of the left hopper cylinder 24L, and discharges the hydraulic fluid flowing out of the rod-side oil chamber of the left hopper cylinder 24L into the hydraulic fluid tank T. In this case, the left hopper cylinder 24L extends. Also, the control valve 34R for the right hopper allows the hydraulic fluid discharged by the cylinder pump 14M to flow into the head-side oil chamber of the right hopper cylinder 24R, and discharges the hydraulic fluid flowing out of the rod-side oil chamber of the right hopper cylinder 24R into the hydraulic fluid tank T. In this case, the right hopper cylinder 24R extends.

[0089] The pilot check valve 34P is configured to prevent the hopper cylinder 24 from contracting and opening due to the weight of the hopper 2, or the weight of the hopper 2 and the paving material inside the hopper 2. In the example shown in Figure 4, the pilot check valve 34P includes pilot check valves 34PL and 34PR. For example, the pilot check valve 34PL allows the hydraulic fluid in the head-side oil chamber of the left hopper cylinder 24L to flow toward the hydraulic fluid tank T only when the control valve 34L for the left hopper operates in response to the operator's operation and the hydraulic fluid discharged by the cylinder pump 14M flows into the rod-side oil chamber of the left hopper cylinder 24L. In all other cases, the pilot check valve 34PL prohibits the hydraulic fluid in the head-side oil chamber of the left hopper cylinder 24L from flowing toward the hydraulic fluid tank T. The same applies to the pilot check valve 34PR.

[0090] In the hopper drive unit F6, a pilot check valve is not installed between the rod-side oil chamber of the hopper cylinder 24 and the hopper control valve 34. This is because the hopper 2 is heavy, making it unlikely that the hopper cylinder 24 will unintentionally extend due to external forces. However, a pilot check valve may be installed between the rod-side oil chamber of the hopper cylinder 24 and the hopper control valve 34.

[0091] The screed lift section F7 is configured to lift the screed 3. In this embodiment, the screed lift section F7 mainly includes a screed lift cylinder 25, a screed lift control valve 35, a switching valve 35a, a relief valve 35b, and a switching valve 35c.

[0092] The screed lift cylinder 25 is a hydraulic actuator that lifts the screed 3, contracting when lifting the screed 3 and extending when lowering the screed 3. In the example shown in Figure 4, the screed lift cylinder 25 includes a left screed lift cylinder 25L and a right screed lift cylinder 25R.

[0093] The screed lift control valve 35 is configured to operate in response to a control signal from the controller 50. When lifting the screed 3, the screed lift control valve 35 allows the hydraulic fluid discharged by the cylinder pump 14M to flow into the rod-side oil chamber of the screed lift cylinder 25. In this case, the switching valve 35a is switched to a first position including a check valve in response to a control signal from the controller 50. This is to prevent hydraulic fluid from flowing back from the rod-side oil chamber of the screed lift cylinder 25 towards the hydraulic fluid tank T. The hydraulic fluid flowing out from the head-side oil chamber of the screed lift cylinder 25 is discharged into the hydraulic fluid tank T without passing through the screed lift control valve 35. In this case, the screed lift cylinder 25 retracts. On the other hand, when lowering the screed 3 to the ground, the screed lift control valve 35 is not used (it remains in the state shown in Figure 4). In this case, the switching valve 35a is switched to a second position without a check valve in response to a control signal from the controller 50. This is to allow the hydraulic fluid from the rod-side oil chamber of the screed lift cylinder 25 to flow out towards the hydraulic fluid tank T. As a result, the screed lift cylinder 25 extends due to the weight of the screed 3, and the hydraulic fluid from the rod-side oil chamber of the screed lift cylinder 25 is discharged into the hydraulic fluid tank T through the switching valve 35a and the relief valve 35b.

[0094] The switching valve 35a and the relief valve 35b enable the vertical movement of the screed 3 in response to changes in lift (the force with which the paving material tries to lift the screed 3) generated when the asphalt paver 100 moves and paves the road. Specifically, when the screed 3 rises due to an increase in lift, the screed lift cylinder 25 contracts. In this case, the hydraulic fluid discharged by the cylinder pump 14M flows into the rod-side oil chamber of the screed lift cylinder 25 through the pipeline C3, the screed lift control valve 35, and the switching valve 35a. On the other hand, when the screed 3 descends due to a decrease in lift, the screed lift cylinder 25 extends. In this case, the hydraulic fluid flowing out of the rod-side oil chamber of the screed lift cylinder 25 is discharged into the hydraulic fluid tank T through the switching valve 35a, the screed lift control valve 35, and the relief valve 35b. Furthermore, when the asphalt paver 100 is paving the road while moving, that is, when the hydraulic equipment such as the screed extension section F8 located downstream is not being used, the switching valve 35c is switched to a first position including the check valve in response to a control signal from the controller 50. This is to prevent adverse effects on the hydraulic equipment such as the screed extension section F8 located downstream. Specifically, this is to prevent the extension screed 31, crown device, and step device from moving unintentionally.

[0095] The screed extension section F8 is configured to allow the extension screed 31 to extend and retract in the vehicle width direction. In this embodiment, the screed extension section F8 mainly includes a screed extension cylinder 27, a screed extension control valve 37, a pilot check valve 37P, and a relief valve 37V. In the example shown in Figure 4, the screed extension control valve 37 includes a left screed extension control valve 37L and a right screed extension control valve 37R. The pilot check valve 37P includes pilot check valves 37PaL, 37PaR, 37PbL, and 37PbR. The relief valve 37V includes a left relief valve 37VL and a right relief valve 37VR.

[0096] The left screed extension control valve 37L is configured to operate in response to a control signal from the controller 50. When retracting the left extension screed 31L, the left screed extension control valve 37L allows the hydraulic fluid discharged by the cylinder pump 14M to flow into the rod-side oil chamber of the left screed extension cylinder 27L, and discharges the hydraulic fluid flowing out of the head-side oil chamber of the left screed extension cylinder 27L into the hydraulic fluid tank T. In this case, the left screed extension cylinder 27L contracts, and the left extension screed 31L is retracted. The same applies when retracting the right extension screed 31R. On the other hand, when pushing out the left extension screed 31L, the left screed extension control valve 37L allows the hydraulic fluid discharged by the cylinder pump 14M to flow into the head-side oil chamber of the left screed extension cylinder 27L, and discharges the hydraulic fluid flowing out of the rod-side oil chamber of the left screed extension cylinder 27L into the hydraulic fluid tank T. In this case, the left screed extension cylinder 27L extends, and the left screed extension cylinder 31L is pushed out.

[0097] The pilot check valve 37P is configured to prevent the screed extension cylinder 27 from moving unintentionally due to external forces. For example, the pilot check valve 37PaL allows the hydraulic fluid in the rod-side oil chamber of the left screed extension cylinder 27L to flow toward the hydraulic fluid tank T only when the left screed extension control valve 37L operates in response to the operator's operation and the hydraulic fluid discharged by the cylinder pump 14M flows into the head-side oil chamber of the left screed extension cylinder 27L. In all other cases, the pilot check valve 37PaL prohibits the hydraulic fluid in the rod-side oil chamber of the left screed extension cylinder 27L from flowing toward the hydraulic fluid tank T. The same applies to the pilot check valves 37PbL, 37PaR, and 37PbR.

[0098] The relief valve 37V is configured to prevent damage to components associated with the telescopic screed 31 due to excessive external force acting in the direction of retracting the telescopic screed 31. For example, the left relief valve 37VL allows the hydraulic fluid in the head-side oil chamber of the left screed telescopic cylinder 27L to flow out into the hydraulic fluid tank T if the hydraulic fluid pressure in the head-side oil chamber of the left screed telescopic cylinder 27L rises excessively due to excessive external force acting in the direction of contracting the left screed telescopic cylinder 27L. As a result, the left screed telescopic cylinder 27L contracts and absorbs part of the external force, preventing damage to the left screed 31L. The same applies to the right relief valve 37VR.

[0099] <Controller Function Blocks> Returning to Figure 2, we will now describe each functional block within the controller 50 of the asphalt finisher 100. Each functional block within the controller 50 is conceptual and does not necessarily need to be physically configured as shown in the figure. All or part of each functional block can be configured by distributing and integrating them functionally or physically in any unit. Each processing function performed in each functional block is realized, all or any part thereof, by a program executed on the CPU. Alternatively, each functional block may be realized as hardware using wired logic. The program executed in the controller 50 according to this embodiment is not limited to being stored in a non-volatile auxiliary storage device, but may also be stored in a distributable storage medium or transmitted and received via a communication line.

[0100] In this embodiment, the controller 50 performs self-position estimation according to the detection results from the GPS module 54, the forward monitoring device 51F, the rear monitoring device 51B, and the driving speed sensor 47, and performs automatic movement control to pave the road surface with asphalt according to the schedule information stored in the auxiliary storage device 48.

[0101] At that time, the controller 50 transmits a control command to the screed control device 55 to extend or retract the retractable screed 31, based on measurement information from the right-side monitoring device 51R, the left-side monitoring device 51L, and the screed length detection device 57, so that the paving material does not extend beyond the road surface to be paved.

[0102] The asphalt finisher 100 according to this embodiment spreads the paving material evenly onto the road surface to be paved. The amount of paving material that the asphalt finisher 100 spreads onto the road surface varies depending on the road surface conditions. The amount of paving material spread onto the road surface is adjusted by changing the rotation speed of the screw SC.

[0103] Traditionally, asphalt pavers need to spread an appropriate amount of paving material for the road's surface area. However, roads to be paved are often curved. The road surface conditions differ between curved roads and straight roads. For example, on a curved road, the surface area differs between the right and left sides of the asphalt paver. In such cases, conventional asphalt pavers did not take into account the need to adjust the amount of paving material spread on the road surface according to changes in the road surface conditions.

[0104] In contrast, the asphalt finisher 100 according to this embodiment adjusts the amount of paving material spread according to changes in the road surface conditions by adjusting the rotation speed of the screw SC. The configuration for realizing this control is described below.

[0105] More specifically, the controller 50 has, as a functional block composed of software, hardware, or a combination thereof, an acquisition unit 50a, a movement path calculation unit 50b, a movement control unit 50c, a screed control unit 50d, and a screw rotation control unit 50e.

[0106] The acquisition unit 50a acquires various types of information. For example, the acquisition unit 50a acquires measurement information from various sensors. For example, the acquisition unit 50a acquires measurement information detected by the forward monitoring device 51F, the rear monitoring device 51B, the right-side monitoring device 51R, and the left-side monitoring device 51L. The acquisition unit 50a also acquires measurement information detected by the driving speed sensor 47 (for example, including the speed of the asphalt finisher 100). The acquisition unit 50a also acquires measurement information from the screed length detection device 57 (the length to which the left telescopic screed 31L and the right telescopic screed 31R are extended in the vehicle width direction). Furthermore, the acquisition unit 50a acquires position information from the GPS module 54. Furthermore, the acquisition unit 50a acquires information from the auxiliary storage device 48 as needed. The acquisition unit 50a may also acquire steering angle information from the tractor 1.

[0107] The movement path calculation unit 50b calculates the target movement path of the asphalt finisher 100 based on the schedule information read from the schedule information storage unit 48a. The target movement path is information that indicates the path along which the structural center position of the asphalt finisher 100 in the vehicle width direction (in other words, in the vehicle width direction between the left side and the right side of the asphalt finisher 100) moves in order for the asphalt finisher 100 to work on the road surface. Note that the target movement path is not limited to a method calculated within the controller 50, but may also be received from an external device via the communication device 53. Furthermore, the target movement path is not limited to the above-mentioned path, but may be any path along which the asphalt finisher 100 can move, for example, the trajectory of the left front wheel of the tractor 1.

[0108] The movement control unit 50c outputs control commands to the drive system controller 52 based on the measurement information and position information acquired by the acquisition unit 50a, so that the asphalt finisher 100 moves along the calculated target movement path. This enables automatic movement control of the asphalt finisher 100.

[0109] The screed control unit 50d outputs a control command to the screed control device 55 to extend or retract the retractable screed 31, based on measurement information (an example of detection result) from the right-side monitoring device 51R, the left-side monitoring device 51L, and the screed length detection device 57, so as to correspond to the width of the road surface on which the paving material is to be spread. This makes it possible to match the length of the screed 3 in the vehicle width direction with the width of the road being constructed, so that the paving material can be properly spread and leveled on the road surface to be paved.

[0110] Figure 5 shows the configuration of the screw SC and screed 3 in the asphalt finisher 100 according to this embodiment. Figure 5 shows an example where the asphalt finisher 100 is moving in the direction of travel 4001. The screw SC provided on the asphalt finisher 100 rotates in direction 4002 according to the control signal from the controller 50. As a result, the paving material is pushed out in direction 4003.

[0111] In the example shown in Figure 5, the edge of the road surface to be paved (the boundary between the road surface and the shoulder) is set as the target line OL (left target line OLL) on the side plate 40 of the asphalt finisher 100.

[0112] Then, as the asphalt finisher 100 moves in the direction of travel 4001, if the road surface changes or the steering angle of the asphalt finisher 100 changes, the target line OL, which is the boundary between the road surface and the shoulder, shifts to the right or left, relative to the center position of the asphalt finisher 100 in the width direction.

[0113] In this embodiment, the acquisition unit 50a of the controller 50 detects the deviation (change) of the target line OL (for example, the left target line OLL) based on measurement information from the right monitoring device 51R and the left monitoring device 51L. Based on the detection result, the screed control unit 50d transmits a control command to the screed control device 55 to extend or retract the retractable screed 31 so that the side plate 40 is aligned with the target line (for example, the left target line OLL).

[0114] This allows the side plate 40 to move to the right 4011 or to the left 4012 so as to follow the target line OL.

[0115] Returning to Figure 2, the screw rotation control unit 50e outputs a control command to the screw control device 56 to rotate the screw SC in accordance with the current status of the asphalt finisher 100. Specifically, the screw rotation control unit 50e determines the rotation speed of the screw SC by referring to the screw rotation speed storage unit 48c using the measurement information acquired by the acquisition unit 50a and the steering angle control command value as search keys. Then, the screw rotation control unit 50e outputs a control command to the screw control device 56 to rotate the screw SC at that rotation speed. This allows the asphalt finisher 100 to spread an appropriate amount of paving material onto the road surface on which it is traveling.

[0116] The rotational speed of the screw SC according to this embodiment is determined, for example, according to changes in the road surface on which the asphalt finisher 100 is traveling.

[0117] As described above, when the left retractable screed 31L and the right retractable screed 31R are extended or retracted by the screed control unit 50d, the area over which the asphalt finisher 100 spreads the paving material changes. In this case, the screw rotation control unit 50e changes the rotation speed of the screw SC so that an amount of paving material corresponding to the changed area can be spread on the road surface.

[0118] Figure 6 is a diagram illustrating the length of the screed 3 from the rear of the asphalt finisher 100 according to this embodiment. In this embodiment, the vehicle width memory unit 48b stores the length 5001 from the center position in the vehicle width direction of the asphalt finisher 100 to the left side, and the length 5002 from the center position in the vehicle width direction to the right side.

[0119] The screed length detection device 57 then detects the length 5011 from the left side to the far end of the left telescopic screed 31L, and the length 5012 from the right side to the far end of the right telescopic screed 31R.

[0120] As a result, the acquisition unit 50a of the controller 50 can acquire the left-side pavement target length 5051 from the center position in the vehicle width direction (an example of the center) to the far end of the left-extending screed 31L, and the right-side pavement target length 5052 from the center position in the vehicle width direction (an example of the center) to the far end of the right-extending screed 31R, based on the detection results from the screed length detection device 57 (an example of the detection unit) and the lengths 5001 and 5002 stored in the vehicle width storage unit 48b.

[0121] Subsequently, the acquisition unit 50a calculates the ratio of the left pavement target length 5051 to the right pavement target length 5052.

[0122] The screw rotation control unit 50e according to this embodiment changes the rotation speed of the left and right screws SC according to the ratio of the left and right lengths of the area to be paved. For example, if the length ratio is 1:1.5, the rotation speed is changed so that the amount of paving material spread is 1:1.5. In this embodiment, the change in rotation speed is specified by referring to the screw rotation speed storage unit 48c.

[0123] <Explanation of the asphalt finisher's movement route> Furthermore, the amount of paving material spread on the road surface changes if the direction of travel of the asphalt finisher 100 changes. Therefore, the amount of paving material spread on the road surface will be explained based on the movement path of the asphalt finisher 100.

[0124] Figure 7 shows the target movement path of the asphalt finisher 100 based on the schedule information according to this embodiment. Figure 7 shows an example in which the asphalt finisher 100 moves along the road 6001 in the direction of travel 6011.

[0125] Then, the movement control unit 50c of the asphalt finisher 100 controls the movement of the tractor 1 so that the center position of the asphalt finisher 100 in the width direction matches the path CL of the road to be paved, in order to move according to the road to be paved.

[0126] Furthermore, the screed control unit 50d outputs a control command to the screed control device 55 to extend or retract the left retractable screed 31L so that the left side plate 40L aligns with the left target line OLL. Similarly, the screed control unit 50d outputs a control command to the screed control device 55 to extend or retract the right retractable screed 31R so that the right side plate 40R aligns with the right target line OLR. As a result, even if the center position of the asphalt finisher 100 in the width direction is slightly offset from the center of the road to be paved, the paving material can be properly spread and leveled on the road surface to be paved.

[0127] In the example shown in Figure 7, when the asphalt finisher 100 is moving along path CL, if the center position of the asphalt finisher 100 in the vehicle width direction is at the center of the road, then the length of the pavement target on the left side is L1, from the center position in the vehicle width direction to the left edge of the road, and the length of the pavement target on the right side is L1, from the center position in the vehicle width direction to the right edge of the road. Furthermore, from the left pavement target length L1 and the right pavement target length L1, the ratio of the pavement target on the left side to the right side is L1:L1.

[0128] The screw rotation control unit 50e then calculates the rotation speeds of the left screw motor 21SL and the right screw motor 21SR based on the travel speed of the asphalt finisher 100 and the ratio of the lengths of the paving targets on the left and right sides, and outputs a control command corresponding to the rotation speed.

[0129] In the asphalt paver 100, the movement control unit 50c automatically controls the asphalt paver 100 to move along the road 6001. To this end, the movement control unit 50c controls the steering angle of the tractor 1 in accordance with the changes in the left-right direction of the road 6001.

[0130] Figure 7 shows an example in which the movement control unit 50c controls the steering angle to turn to the left in accordance with the road 6001. In the example shown in Figure 7, the asphalt finisher 100 is shown turning to the left with respect to the turning center 6021.

[0131] As shown in Figure 7, when the road 6001 is curved, the timing at which the movement control unit 50c changes the steering angle of the tractor 1 causes the center position of the asphalt finisher 100 in the vehicle width direction to shift from the center of the road 6001. In the example shown in Figure 7, this shift results in a left-side paving target length L3 from the center position in the vehicle width direction to the left edge of the road, and a right-side paving target length L2 from the center position in the vehicle width direction to the right edge of the road.

[0132] Furthermore, when the asphalt finisher 100 turns to the left, the radius of the area to be paved to the right of the center position in the width direction of the asphalt finisher 100 and the area to be paved to the left of the center position in the width direction of the asphalt finisher 100 are different, with respect to the turning center 6021. In other words, in addition to the difference between the left-side paving area length L3 and the right-side paving area length L2, a difference arises between the right-side area 6031 of the paving area to the right of the center position in the width direction of the asphalt finisher 100 and the left-side area 6032 of the paving area to the left of the center position in the width direction of the asphalt finisher 100, based on this radius.

[0133] It is necessary to determine the amount of paving material to be spread corresponding to the area of ​​the right side 6031 and the area of ​​the left side 6032. Therefore, the screw rotation control unit 50e refers to the screw rotation speed memory unit 48c to determine the rotation speed of the left screw motor 21SL and the right screw motor 21SR so as to spread the amount of paving material corresponding to the area of ​​the right side 6031 and the area of ​​the left side 6032, and outputs a control command corresponding to that rotation speed.

[0134] As shown in Figure 3, the screw rotation speed memory unit 48c associates the speed of the asphalt finisher 100, the steering angle, the length from the center position of the asphalt finisher 100 in the vehicle width direction to the far end of the telescopic screed 31, and the rotation speed. This relationship will be explained. First, the steering angle of the tractor 1 and the length from the center position of the asphalt finisher 100 in the vehicle width direction to the far end of the telescopic screed 31 allow us to determine the right-side area 6031 and the left-side area 6032 at a predetermined angle θ with respect to the turning center 6021. The time required for the asphalt finisher 100 to travel a distance CLA (see Figure 7) can also be determined from the speed of the asphalt finisher 100. Therefore, the screw rotation speed memory unit 48c is set to the rotation speeds of the left screw motor 21SL and the right screw motor 21SR so that the required amount of paving material can be spread to the right area 6031 and the left area 6032 in the time required to travel the distance CLA. As a result, for example, when turning to the left, the screw rotation control unit 50e outputs a control command to increase the rotation speed of the left screw motor 21SL and decrease the rotation speed of the right screw motor 21SR compared to before the turn. The steering angle of the tractor 1 may be the command value of the movement control by the movement control unit 50c, or it may be measurement information acquired from the tractor 1 by the acquisition unit 50a.

[0135] As a result, the screw rotation control unit 50e can refer to the screw rotation speed memory unit 48c to determine the rotation speed of the left screw motor 21SL and the right screw motor 21SR, respectively, according to the current status of the asphalt finisher 100. Then, by outputting a control command to rotate at the determined rotation speed, the screw rotation control unit 50e can spread an appropriate amount of paving material onto the road surface on which the asphalt finisher 100 is running.

[0136] In other words, in this embodiment, when the asphalt finisher 100 is being moved by the tractor 1, the movement control unit 50c changes the steering angle of the tractor 1, and the screw rotation control unit 50e controls the rotation speed of the screw SC to change.

[0137] Specifically, when the tractor 1 is moving, if the steering angle of the tractor 1 is changed by the movement control unit 50c, the screw rotation control unit 50e controls the rotation speed of the right screw SCR and the left screw SCL to be different, according to the area on the right side 6031 of the paving target and the area on the left side 6032 of the paving target.

[0138] In this embodiment, an example has been described in which the rotational speeds of the left screw motor 21SL and the right screw motor 21SR are determined by referring to the screw rotational speed memory unit 48c. However, this embodiment does not limit the method for determining the rotational speeds of the left screw motor 21SL and the right screw motor 21SR to the example of referring to a table. For example, the rotational speeds of the left screw motor 21SL and the right screw motor 21SR may be determined by a calculation formula. Possible calculation formulas include formulas that calculate the rotational speed by substituting the speed of the asphalt finisher 100, the steering angle, and the length from the center position of the asphalt finisher 100 in the vehicle width direction to the far end of the telescopic screed 31 as parameters. Furthermore, the formula for calculating the rotational speed is not limited to using the speed of the asphalt finisher 100, the steering angle, and the length from the center position of the asphalt finisher 100 in the vehicle width direction to the far end of the telescopic screed 31; the rotational speed may be calculated using one or more of these parameters. Also, any method may be used to calculate the rotational speed, regardless of whether it is a well-known method.

[0139] <Explanation of control procedures in automatic movement control using an asphalt finisher> Figure 8 is a flowchart showing the control of the asphalt paver 100 by the controller 50 according to this embodiment.

[0140] First, the acquisition unit 50a of the controller 50 acquires schedule information from the schedule information storage unit 48a of the auxiliary storage device 48 before performing automatic control (S7001).

[0141] The movement path calculation unit 50b calculates the target movement path of the asphalt finisher 100 according to the schedule information (S7002).

[0142] Then, the movement control unit 50c starts movement control to move according to the calculated target movement path (S7003).

[0143] The acquisition unit 50a acquires location information from the GPS module 54 and also acquires measurement information from the forward monitoring device 51F, the rear monitoring device 51B, the driving speed sensor 47, and the screed length detection device 57 (S7004).

[0144] The movement control unit 50c performs movement control to move according to the target movement path based on the position information and the measurement information from the forward monitoring device 51F, the rear monitoring device 51B, and the travel speed sensor 47 (S7005).

[0145] The screw rotation control unit 50e determines whether the movement control unit 50c has performed rudder angle control according to the target movement path (S7006). If it is determined that rudder angle control has not been performed (S7006: NO), the process proceeds to S7008.

[0146] If the screw rotation control unit 50e determines that the movement control unit 50c has performed rudder angle control according to the target movement path (S7006: YES), the screw rotation control unit 50e refers to the screw rotation speed memory unit 48c and changes the rotation speed of the left screw motor 21SL and the right screw motor 21SR respectively based on the rudder angle changed by the movement control unit 50c (S7007).

[0147] Furthermore, the screed control unit 50d determines whether the side plate 40 is deviated from the target line based on the measurement information from the right-side monitoring device 51R and the left-side monitoring device 51L acquired by the acquisition unit 50a, as well as the detection results from the screed length detection device 57 (S7008). If it is determined that the side plate 40 is not deviated from the target line (S7008: NO), the process proceeds to S7011.

[0148] On the other hand, if the screed control unit 50d determines that the side plate 40 is misaligned with the target line (S7008: YES), it outputs a control command to the screed control device 55 to extend or retract the retractable screed 31 in order to align the side plate 40 with the target line (S7009).

[0149] Furthermore, the screw rotation control unit 50e controls the screed control device 55 by referring to the screw rotation speed memory unit 48c, and then changes the rotation speed of the left screw motor 21SL and the right screw motor 21SR respectively according to the ratio of the left pavement target length 5051 and the right pavement target length 5052 of the screed 3 (S7010).

[0150] Subsequently, the movement control unit 50c determines whether or not movement along the target movement path has been completed (S7011). If it determines that movement along the target movement path has not been completed (S7011), the process returns to S7004.

[0151] On the other hand, the movement control unit 50c terminates processing when it determines that movement according to the target movement path has been completed (S7011: YES).

[0152] In this embodiment, the case where the steering angle of the tractor 1 is changed when the direction of travel of the asphalt finisher 100 is changed has been described. In other words, when the steering angle of the tractor 1 is changed, the rotational speeds of the left screw motor 21SL and the right screw motor 21SR are changed. However, the information for changing the rotational speeds of the left screw motor 21SL and the right screw motor 21SR is not limited to information indicating a change in the steering angle of the tractor 1. For example, the rotational speeds of the left screw motor 21SL and the right screw motor 21SR may be changed based on the target travel path calculated by the travel path calculation unit 50b. For example, the screw rotation control unit 50e may change the rotational speeds of the left screw motor 21SL and the right screw motor 21SR at the timing when the asphalt finisher 100 changes direction of travel along the target travel path.

[0153] In this embodiment, the controller 50 can change the rotational speed of the left screw motor 21SL and the right screw motor 21SR when the steering angle is changed in accordance with the direction of travel while the asphalt finisher 100 is moving. Furthermore, when the asphalt finisher 100 is moving, the controller 50 can change the rotational speed of the left screw motor 21SL and the right screw motor 21SR when controlling the extension and retraction of the retractable screed 31 in accordance with the width of the road. This allows the controller 50 to spread an amount of paving material corresponding to the area of ​​the road to be paved. Therefore, by spreading an appropriate amount of paving material for the road, the controller 50 can prevent shortages or surpluses of paving material on the road, thereby improving the quality of paving work.

[0154] (Variation 1) In the embodiments described above, an example was explained in which the movement control unit 50c of the asphalt finisher 100 performs automatic movement control so that it follows a target movement path. However, the embodiments described above are not limited to a method of performing automatic movement control so that it follows a target movement path. Therefore, in this modified example, a case in which an operator operates the asphalt finisher 100 will be described.

[0155] In this modified example, the movement control unit 50c outputs a control command to the drive system controller 52 to move the asphalt finisher 100 in accordance with the operator's operation on the steering device. This controls the movement of the asphalt finisher 100.

[0156] The acquisition unit 50a in this modified example detects the edge of the road surface to be paved (the boundary between the road surface and the shoulder) based on measurement information from the right-side monitoring device 51R and the left-side monitoring device 51L, and sets the said edge of the road surface as the target line OL of the side plate 40. Subsequent processing is the same as in the embodiment described above.

[0157] In other words, the screed control unit 50d in this modified example outputs a control command to the screed control device 55 to extend or retract the retractable screed 31 so that the side plate 40 aligns with the target line OL.

[0158] Furthermore, the screw rotation control unit 50e in this modified example, similar to the embodiment described above, determines the rotation speed of the left screw motor 21SL and the right screw motor 21SR based on the ratio of the length of the paving target to the left of the center position in the vehicle width direction of the asphalt finisher 100 to the length of the paving target to the right of the center position in the vehicle width direction, and outputs a control command corresponding to the determined rotation speed.

[0159] Furthermore, the screw rotation control unit 50e in this modified example, similar to the embodiment described above, identifies the rotational speed of the left screw motor 21SL and the right screw motor 21SR in accordance with the steering angle control performed by the operator, and outputs a control command corresponding to the identified rotational speed.

[0160] In this modified example, the controller 50 can perform the control described above, thereby achieving the same effects as in the embodiment described above.

[0161] (Modification 2) In Modification 1, the movement of the asphalt finisher 100 is controlled according to the operator's commands, but the extension and retraction of the retractable screed 31 is performed by the screed control unit 50d based on measurement information. However, the extension and retraction of the retractable screed 31 is not limited to automatic control by the controller 50. This modification describes the case where the operation is performed by a worker.

[0162] In this modified example, as shown in Figure 6, the input unit 58L receives an operation from the operator to extend the left retractable screed 31L relative to the main screed 30 to the left side in the vehicle width direction. Similarly, the input unit 58R receives an operation from the operator to extend the right retractable screed 31R relative to the main screed 30 to the right side in the vehicle width direction. The input units 58L and 58R output the information of the received operation to the controller 50.

[0163] Furthermore, the screw rotation control unit 50e in this modified example determines the rotation speed of the left screw motor 21SL and the right screw motor 21SR based on the ratio of the length of the paving target to the left of the center position in the vehicle width direction of the asphalt finisher 100 after the extension and retraction of the telescopic screed 31 to the length of the paving target to the right of the center position in the vehicle width direction, and outputs a control command corresponding to the determined rotation speed. This makes it possible to obtain the same effects as in the embodiment described above.

[0164] (Variation 3) The above-described embodiment explained the case in which the steering angle of the tractor 1 is changed when the direction of travel of the asphalt finisher 100 is changed. However, the above-described embodiment is not limited to a method in which the steering angle of the tractor 1 is changed when the direction of travel of the asphalt finisher 100 is changed.

[0165] For example, the above-described embodiment described an example in which the tractor 1 of the asphalt finisher 100 is equipped with front wheels 6 and rear wheels 5. However, the above-described embodiment is not limited to an example in which the tractor 1 is equipped with front wheels 6 and rear wheels 5, and may also be equipped with crawlers (an example of a moving body). In this modified example, an example in which the tractor 1 is equipped with a right-side crawler and a left-side crawler will be described.

[0166] In this case, instead of changing the steering angle of the front wheels 6, the movement control unit 50c changes the direction of travel of the asphalt finisher 100 by changing the rotational speed of the drive wheel of the right crawler (an example of the right-side vehicle) and the drive wheel of the left crawler (an example of the left-side vehicle). In other words, the direction of travel of the asphalt finisher 100 is changed by the difference in rotational speed between the drive wheel of the right crawler (an example of the right-side vehicle) and the drive wheel of the left crawler (an example of the left-side vehicle).

[0167] In other words, the screw rotation control unit 50e according to this modified example changes the rotation speed of the left screw motor 21SL and the right screw motor 21SR, respectively, to correspond to the direction of travel of the asphalt finisher 100, based on information indicating that the rotation speed of the right crawler (an example of the right-side running body) and the left crawler (an example of the left-side running body) should be changed. To achieve this change in rotation speed, for example, the screw rotation speed memory unit may associate the rotation speed of the drive wheel of one crawler with the rotation speed of the drive wheel of the other crawler, the length from the center position in the width direction of the asphalt finisher 100 to the far end of one of the telescopic screeds 31, and the rotation speed of the screw SC.

[0168] Thus, the screw rotation control unit 50e may refer to the screw rotation speed memory unit and change the rotation speeds of the left screw motor 21SL and the right screw motor 21SR based on information indicating the rotation speeds of the right crawler (an example of the right-side running body) and the left crawler (an example of the left-side running body).

[0169] The embodiments and modifications described above illustrate examples in which one or more of the following information is used as information regarding the direction of movement of the asphalt finisher for changing the rotational speed of the left screw motor 21SL and the right screw motor 21SR: steering angle, target movement path for movement control, and information indicating the rotational speed of the right crawler and the left crawler (for example, the difference in rotational speed between the right crawler and the left crawler). Note that the information regarding the direction of movement of the asphalt finisher 100 is not limited to the information described above, and for example, the angle of the steering (wheel) that switches the direction of movement of the tractor 1, the length of the steering cylinder (not shown) that is controlled when switching the direction of movement of the tractor 1 in response to steering operation, or the direction of movement of the tractor 1 may be used. Furthermore, the steering angle used as information regarding the direction of movement of the asphalt finisher 100 may be a command value or an actual steering angle.

[0170] <effect> The controller 50 of the asphalt finisher 100 according to the above-described embodiment and modified example has the above-described configuration, which allows the rotation speed of the screw SC to be changed according to the direction of travel of the asphalt finisher 100, thereby spreading an amount of paving material corresponding to the road to be paved. This prevents shortages or surpluses of paving material on the road, thereby improving the construction quality of the paved road surface.

[0171] Furthermore, the controller 50 of the asphalt finisher 100 according to the embodiment and modified examples changes the rotation speed of the screw SC based on information regarding the direction of travel of the asphalt finisher 100, thus eliminating the need for an operator to ride on the asphalt finisher 100 and adjust the rotation speed of the screw SC. This reduces the cost of construction using the asphalt finisher 100.

[0172] Furthermore, since the Asphalt Finisher 100 can spread an amount of paving material corresponding to the area of ​​the road covered by the compensation, the amount of wasted paving material can be reduced.

[0173] Furthermore, the controller 50 of the asphalt finisher 100 adjusts the rotation speed of the screw SC and controls the lengths of the right-extending screed 31R and the left-extending screed 31L, changing the rotation speed of the screw SC according to the ratio of the lengths of the right-extending screed 31R and the left-extending screed 31L. As a result, the amount of paving material that spills onto areas other than the road being paved is reduced. This reduces the number of workers required to perform subsequent processes on the road after the asphalt finisher 100 has passed, thereby reducing the cost of construction using the asphalt finisher 100.

[0174] Furthermore, the controller 50 of the asphalt finisher 100, when the direction of movement of the asphalt finisher 100 (for example, the steering angle of the tractor 1) is changed while the asphalt finisher 100 is moving with the tractor 1, causes the left screw motor 21SL and the right screw motor 21SR to rotate at different speeds. Therefore, even if the area of ​​the road to be paved differs on the right and left sides of the asphalt finisher 100 due to the change in direction of movement, the amount of paving material corresponding to the area can be spread. This improves the construction quality of the paved road.

[0175] Although embodiments have been described in detail above, this disclosure is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist described in the claims.

[0176] Although embodiments of the asphalt finisher have been described above, the present invention is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These also naturally fall within the technical scope of the present invention. [Explanation of Symbols]

[0177] 100 Asphalt Finisher SCL left screw SCR Right Screw 27L Left Screed Telescopic Cylinder 27R Right Screed Telescopic Cylinder 30 Main Scred 31L Left-hand retractable screed 31R Right-hand retractable screed 47. Driving speed sensor 48 Auxiliary storage device 48a Schedule Information Storage Unit 48b Vehicle width memory unit 50 Controllers 50a Acquisition Department 50b Movement path calculation unit 50c Mobile Control Unit 50d Screed Control Unit 50e Screw Rotation Control Unit 51F Forward monitoring device 51B Rear monitoring device 51R Right side monitoring device 51L Left side monitoring device 52 Drive System Controller 53 Communication equipment 54 GPS modules 55 Screed control device 56 Screw control device 57 Scred length detection device

Claims

1. Tractor and, A hopper installed on the front side of the aforementioned tractor, An asphalt finisher comprising a conveyor for transporting the paving material in the hopper to the rear of the tractor, A screw for spreading the paving material, which has been transported by the conveyor and scattered on the road surface, in the direction of the vehicle width, The vehicle has a screed device that is extendable and retractable in the vehicle width direction, which spreads the paving material laid by the screw on the rear side of the screw, The screed device includes a right-side screed device provided on the right side of the asphalt finisher and a left-side screed device provided on the left side of the asphalt finisher. The screw includes a right screw and a left screw, A storage unit that stores the speed of the asphalt finisher, the steering angle of the tractor, the distance from the center position of the asphalt finisher in the vehicle width direction to the far end of the right screed device and the left screed device, and the rotational speed of the right screw and the left screw in correspondence with each other. The system further includes a detection unit that detects the length by which each of the right-side screed device and the left-side screed device extends or retracts in the vehicle width direction, Based on the detection result from the detection unit, the storage unit, the acquired speed of the asphalt finisher, and the acquired command value of the steering angle of the tractor, the rotational speed of the right screw and the left screw are configured to be changed. Asphalt finisher.

2. Based on the detection result by the detection unit, the right screed device and the left screed device are configured to extend or retract to control their respective lengths so as to correspond to the width of the road surface on which the paving material is spread. The asphalt finisher according to claim 1.

Images