Asphalt finisher

Abstract

To enhance safety.SOLUTION: An asphalt finisher includes a tractor, a hopper installed on the front side of the tractor, a conveyor for conveying a pavement material in the hopper to the rear side of the tractor, a screw for spreading the pavement material conveyed by the conveyor and spread on a road surface in a vehicle width direction, and a screed device expansible in the vehicle width direction for evenly leveling on the rear side of the screw the pavement material spread by the screw. Expansion / contraction of the screed device is controlled so that the length in the vehicle width direction of the screed device does not fall below the prescribed length based on the screw.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 in front of the tractor for receiving 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 at the rear side of the tractor, and a screed for leveling the paving material spread by the screw at the rear side of the screw.

[0003] When the asphalt finisher performs construction, a design drawing is created, and construction is performed to level the paving material on the road surface based on the design drawing. Various techniques have been proposed to facilitate such construction. For example, in Patent Document 1, a technique for automatically correcting the length in the vehicle width direction of the screed when performing automatic steering 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] By the way, in an asphalt finisher, a side plate extending forward is provided at the distal end of the screed. Therefore, when changing the length in the vehicle width direction of the screed, there is a possibility that the side plate may contact the screw.

[0006] This possibility exists not only when automatic steering automatically corrects the length of the screed in the vehicle width direction, but also when an operator adjusts the length of the screed in the vehicle width direction in an asphalt finisher.

[0007] In light of the above, the side plates are prevented from contacting the screws by controlling the length of the screed of the asphalt finisher in the vehicle width direction so that it does not fall below a predetermined length. [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 of the tractor, a conveyor for transporting paving material in the hopper to the rear of the tractor, a screw for spreading the paving material transported by the conveyor and spread on the road surface in the vehicle width direction, and a screed device that is extendable and retractable in the vehicle width direction for leveling the paving material spread by the screw behind the screw, wherein when controlling the reduction of the screed device to correspond to the width of the road surface on which the paving material is spread, the control for reducing the screed device is suppressed when the length of the screed device in the vehicle width direction is a predetermined length, the screw can be connected to one or more of a plurality of types of expansion screws, and the predetermined length when an expansion screw is connected to the screw is a length determined based on information identifying the connected expansion screw. Furthermore, the information identifying the expansion screw is information provided on the expansion screw and read by a predetermined reader. . [Effects of the Invention]

[0009] According to one aspect of the present invention, safety is improved by controlling the length of the screed of the asphalt finisher in the vehicle width direction so that it does not fall below a predetermined length, thereby suppressing contact between the side plate and 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 a hydraulic circuit diagram showing an example of the configuration of a hydraulic system mounted on an asphalt finisher according to the embodiment. [Figure 4] Figure 4 is an explanatory diagram of the screw provided in the asphalt finisher according to the embodiment. [Figure 5] Figure 5 shows the travel path of the asphalt finisher based on the schedule information according to the embodiment. [Figure 6] Figure 6 shows the positional relationship between the left side plate and the screw according to the embodiment. [Figure 7] Figure 7 is a flowchart showing the control of an asphalt finisher by a controller according to this embodiment. [Figure 8] Figure 8 shows a rear view of an asphalt finisher according to a modified example. [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] Tractor 1 is a mechanism for driving the asphalt finisher 100. In the example shown in Figure 1, tractor 1 moves the asphalt finisher 100 by rotating the rear wheels 5 using a rear-wheel drive motor 20 (see Figure 3) and rotating the front wheels 6 using a front-wheel drive motor 22 (see Figure 3). Both the rear-wheel drive motor 20 and the front-wheel drive motor 22 are hydraulic motors that rotate by receiving hydraulic fluid from a hydraulic pump. However, tractor 1 may be equipped with crawlers instead of wheels.

[0015] The hopper 2 is a mechanism for receiving paving materials. The paving materials are, for example, asphalt mixtures or 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 the hopper cylinder 24. The asphalt finisher 100 usually receives the paving materials from the cargo bed of the dump truck with the hopper 2 fully open. Also, when the asphalt finisher 100 is receiving the paving materials from the cargo bed of the dump truck, it continues to travel while pushing the dump truck forward via the push roller 2b. FIGS. 1(A) and 1(B) show the asphalt finisher 100 when the hopper 2 is in the fully open state. The operator of the asphalt finisher 100 closes the hopper 2 when the paving materials in the hopper 2 decrease, and collects the paving materials near the inner wall of the hopper 2 to 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 the screw SC.

[0016] 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 materials in the hopper 2 to the rear side of the tractor 1 via the conveyance passage CP. The conveyance 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.

[0017] 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 main screw SCLM, a right main screw SCRM, a first left extension screw SCLE1, and a first right extension screw SCRE1. The left conveyor is configured to send the paving material toward the left main screw SCLM. The right conveyor is configured to send the paving material toward the right main screw SCRM. The left main screw SCLM and the right main screw SCRM are arranged within the width of the tractor 1. The left extension screw SCLE is connected to the left end of the left main screw SCLM and is arranged to protrude leftward from the width of the tractor 1. The right extension screw SCRE is connected to the right end of the right main screw SCRM and is arranged to protrude rightward from the width of the tractor 1.

[0018] 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 contraction of the screed lift cylinder 25. The leveling arm 3A includes a left leveling arm 3AL and a right leveling arm 3AR.

[0019] 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 and a right screed retractable cylinder 27R. The left screed retractable cylinder 27L can extend and retract the left 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 screed 31R to the right side in the vehicle width direction relative to the main screed 30.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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 and a rear monitoring device 51B.

[0034] 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.

[0035] 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.

[0036] The spatial recognition device 51 may include a side-monitoring device configured to monitor the side of the asphalt finisher 100. In this case, the side-monitoring device may be mounted on the left end of the upper surface of the tractor 1 in front of the rear wheels 5, for example, as a LIDAR whose monitoring range is the space to the left of the tractor 1. The side-monitoring device may be mounted on the right end of the upper surface of the tractor 1 in front of the rear wheels 5, for example, as a LIDAR whose monitoring range is the space to the right of the tractor 1.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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 and a screw length storage unit 48b.

[0045] 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.

[0046] The screw length storage unit 48b stores information about the length of the screw SC provided by the asphalt finisher 100. In this embodiment, for example, if an extension screw (for example, a first left extension screw SCLE1 or a first right extension screw SCRE1) is connected to the main screw (left main screw SCLM or right main screw SCRM) of the asphalt finisher 100, the screw length storage unit 48b stores information about the length of the screw SC after it has been connected.

[0047] Furthermore, the screw length storage unit 48b may also contain information regarding extension screws that can be attached to the asphalt finisher 100. For example, the screw length storage unit 48b may store the length of the main screws (left main screw SCLM or right main screw SCRM) provided on the asphalt finisher 100. Furthermore, for each extension screw that can be connected to the asphalt finisher 100, the screw length storage unit 48b may store information identifying the extension screw (e.g., model number, RFID, or 2D barcode) in association with the length of the extension screw.

[0048] Therefore, when an extension screw is connected to the asphalt finisher 100, the controller 50 can recognize the length of the screw SC of the asphalt finisher 100 from the information stored in the screw length storage unit 48b. Furthermore, this correspondence is not limited to the method stored in the auxiliary storage device 48, but may also be maintained by a server that can communicate with the asphalt finisher 100.

[0049] 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.

[0050] The screed length detection device 57 detects the length by which the retractable screed 31 expands or contracts in the vehicle width direction. The screed length detection device 57 can use any sensor that can detect the length by which the retractable screed 31 expands or contracts in the vehicle width direction, for example, an imaging device may be used. If an imaging device is used, the retractable screed 31 is imaged, and the length of the retractable screed 31 in the vehicle width direction is determined from the captured image.

[0051] The communication device 53 communicates wirelessly with devices surrounding the asphalt finisher 100, such as road rollers, portable communication devices, RFID readers, etc. In this embodiment, one or more of the following may be used as the wireless communication standard for the communication device 53: for example, Wi-Fi®, wireless LAN, and Bluetooth®.

[0052] 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.

[0053] 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 3, 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.

[0054] The screed control device 55 then performs the following actions in accordance with the control commands from the controller 50: contracting the screed extension cylinder 27 to shorten the left extension screed 31L, and extending the screed extension cylinder 27 to lengthen the left extension screed 31L.

[0055] 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.

[0056] The controller 50 acquires information from the GPS module 54, the forward monitoring device 51F, the rear monitoring device 51, 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.

[0057] <Explanation of the hydraulic system> Next, with reference to Figure 3, the hydraulic system installed in the asphalt finisher 100 will be described. Figure 3 is a hydraulic circuit diagram showing an example configuration of the hydraulic system installed in the asphalt finisher 100.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] The charge pump 14C is a fixed-displacement hydraulic pump that supplies control fluid to the rear-wheel drive unit F1.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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).

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] The front wheel motor 22 is a fixed-displacement hydraulic motor that forms an open circuit. The front wheel drive valve V2 operates in response to control commands from the controller 50, causing 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 3, the front wheel drive motor 22 includes the left front wheel drive motor 22L and the 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.

[0076] 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.

[0077] 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.

[0078] 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 3, the leveling cylinder 23 includes a left leveling cylinder 23L and a right leveling cylinder 23R.

[0079] 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 3, 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 of 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.

[0080] 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 3, the pilot check valve 33P includes pilot check valves 33PaL, 33PbL, 33PaR, and 33PbR. For example, 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, 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 pilot check valves 33PbL, 33PaR, and 33PbR.

[0081] 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.

[0082] 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 3, the hopper cylinder 24 includes a left hopper cylinder 24L and a right hopper cylinder 24R.

[0083] 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 3, 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.

[0084] 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 3, 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.

[0085] 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.

[0086] 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.

[0087] 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 3, the screed lift cylinder 25 includes a left screed lift cylinder 25L and a right screed lift cylinder 25R.

[0088] 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 3). 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.

[0089] 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.

[0090] 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 3, 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] <Controller Function Blocks> This section describes 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 diagram. 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 by 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 by the controller 50 in 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 NW.

[0095] 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 51, 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.

[0096] In this case, the controller 50 transmits a control command to the screed control device 55 to extend or retract the retractable screed 31 based on the measurement information from the screed length detection device 57, so that the paving material does not extend beyond the road surface to be paved.

[0097] Incidentally, a side plate 40 is attached to the distal end of the telescopic screed 31. Therefore, when the telescopic screed 31 is retracted in the vehicle width direction, the side plate 40 may come into contact with the screw.

[0098] Therefore, the controller 50 according to this embodiment controls the extension and retraction of the retractable screed 31 (an example of a screed device) so that the length of the retractable screed 31 in the vehicle width direction does not fall below a predetermined length based on the screw SC.

[0099] The predetermined length based on the screw SC is a length determined so that the side plate 40 does not come into contact with the screw SC. For example, it is the length of the screw SC in the vehicle width direction plus a predetermined margin, that is, a length greater than or equal to the length of the screw SC in the vehicle width direction. This prevents the retractable screed 31 from coming into contact with the screw SC.

[0100] More specifically, the controller 50 has a communication control unit 50a, a setting unit 50b, an acquisition unit 50c, a movement path calculation unit 50d, a movement control unit 50e, and a screed control unit 50f as functional blocks composed of software, hardware, or a combination thereof.

[0101] The communication control unit 50a transmits and receives information with external devices.

[0102] For example, the communication control unit 50a may receive information about the extension screw connected to the asphalt finisher 100 from an RFID (Radio Frequency Identification) reader or a two-dimensional barcode reader.

[0103] Based on the information about the expansion screw received by the communication control unit 50a, the setting unit 50b registers the length of the screw SC of the asphalt finisher 100 in the screw length storage unit 48b. Next, the expansion screw connected to the asphalt finisher 100 will be described.

[0104] In this embodiment, the asphalt finisher 100 uses different connecting expansion screws depending on the width of the road to be paved.

[0105] Figure 4 is an explanatory diagram of the screw SC provided in the asphalt finisher 100 according to this embodiment. As shown in Figure 4, the asphalt finisher 100 has multiple types of extension screws that can be connected to the left main screw SCLM. In the example shown in Figure 4, there is a first left extension screw SCLE1 and a second left extension screw SCLE2. Each of the first left extension screw SCLE1 and the second left extension screw SCLE2 can be connected to the left main screw SCLM. The length of the first left extension screw SCLE1 is, for example, 1m, and the length of the second left extension screw SCLE2 is, for example, 50cm. Thus, the length of the extension screws differs depending on the type.

[0106] Furthermore, the first left extension screw SCLE1, the second left extension screw SCLE2, and the left main screw SCLM may all be connected. Any connection method may be used, for example, bolt fastening.

[0107] The operator fastens the expansion screw to the main screw according to the width of the road being paved by the asphalt finisher 100. In this embodiment, as described above, the controller 50 needs to recognize the length of the screw SC in order to control the length of the expansion screed 31 in the vehicle width direction so that it does not fall below a predetermined length based on the screw SC.

[0108] Therefore, the worker performs the task of setting the length of the extension screw connected to the asphalt finisher 100.

[0109] For example, if RFID 44L1 is embedded in the first left extension screw SCLE1 and RFID 44L2 is embedded in the second left extension screw SCLE2, the worker reads the RFID (e.g., RFID 44L1) of the extension screw (e.g., the first left extension screw SCLE1) connected to the asphalt finisher 100 with an RFID reader (not shown). The information read by the RFID reader includes information that identifies the extension screw to be connected (e.g., the first left extension screw SCLE1) or information that indicates the length of the extension screw.

[0110] The RFID reader then transmits the read information to the communication device 53 of the asphalt finisher 100.

[0111] The communication control unit 50a then receives information from the RFID reader via the communication device 53 that identifies the connected extension screw (for example, the first left extension screw SCLE1) or information indicating the length of the extension screw.

[0112] Based on the received information, the setting unit 50b registers the length of the screw SC after it has been connected to the asphalt finisher 100 in the screw length storage unit 48b. For example, if the setting unit 50b has received information identifying the expansion screw, it identifies the length of the connected expansion screw from the correspondence between the information identifying the expansion screw (e.g., model number, RFID) stored in the screw length storage unit 48b and the length of the expansion screw. The setting unit 50b then registers the identified length in the screw length storage unit 48b.

[0113] Furthermore, the setting unit 50b registers the length of screw SC, which is the sum of the length of the expansion screw and the length of the main screw, in the screw length storage unit 48b.

[0114] Furthermore, the setting unit 50b sets a predetermined length based on the length of the screw SC, which is used as a reference when controlling the extension and retraction of the screw. Control using the predetermined length will be described later.

[0115] This embodiment describes the case where the source of information about the connected expansion screw is an RFID reader. However, this embodiment does not limit the source to an RFID reader; for example, it could be a worker's portable communication device. For example, if a two-dimensional barcode is attached to the expansion screw, the imaging device of the portable communication device may image the two-dimensional barcode, and the portable communication device may transmit the information extracted from the two-dimensional barcode to the communication device 53. Furthermore, an input device provided on the asphalt finisher 100 may accept input of information about the expansion screw (e.g., model number) or the length of the expansion screw. In these cases, the setting unit 50b registers the length of the expansion screw and the length of screw SC in the screw length storage unit 48b based on the information.

[0116] Furthermore, the controller 50 may output a warning before starting construction if the length of the expansion screw registered by the setting unit 50b does not correspond to the road width in the schedule information stored in the schedule information storage unit 48a. In addition, the controller 50 may suppress the start of automatic control until information on the expansion screw corresponding to the road width in the schedule information is registered.

[0117] Returning to Figure 2, the acquisition unit 50c acquires various types of information. For example, the acquisition unit 50c acquires measurement information from various sensors. For instance, the acquisition unit 50c acquires measurement information from the forward monitoring device 51F, the rear monitoring device 51, the driving speed sensor 47, and the screed length detection device 57. Another example is the acquisition unit 50c acquiring location information from the GPS module 54. Furthermore, the acquisition unit 50c acquires information from the auxiliary storage device 48 as needed.

[0118] The movement path calculation unit 50d calculates the movement path of the asphalt finisher 100 based on the schedule information read from the schedule information storage unit 48a.

[0119] The movement control unit 50e outputs control commands to the drive system controller 52 based on the measurement information and position information acquired by the acquisition unit 50c, so that the asphalt finisher 100 moves along the calculated movement path. This enables automatic movement control of the asphalt finisher 100.

[0120] The screed control unit 50f outputs a control command to the screed control device 55 to extend or retract the retractable screed 31, based on the measurement information (an example of the detection result) from 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 spread evenly on the road surface to be paved.

[0121] However, when the screed control unit 50f controls the retractable screed 31 to shorten it to match the width of the road surface on which the paving material is spread, it suppresses the control to shorten the retractable screed 31 when the length of the retractable screed 31 in the vehicle width direction is a predetermined length.

[0122] Specifically, when the screed control unit 50f controls the retractable screed 31 to retract, if it detects from the measurement information of the screed length detection device 57 that the length of the retractable screed 31 in the vehicle width direction is a predetermined length, it suppresses the control to retract the retractable screed 31 even if the side plate 40 protrudes outward (towards the shoulder) of the road surface. Next, the suppression of the control to retract the retractable screed 31 by the screed control unit 50f will be explained.

[0123] <Explanation of the asphalt finisher's movement route> Figure 5 is a diagram showing the movement path of the asphalt finisher 100 based on the schedule information according to this embodiment. In the example shown in Figure 5, the case in which the asphalt finisher 100 moves in the direction of travel 5001 will be described.

[0124] Then, the movement control unit 50e of the asphalt finisher 100 controls the tractor 1 so that the center of the asphalt finisher 100 aligns with the center line CL1 of the road to be paved, in order to move along the road to be paved.

[0125] Furthermore, the screed control unit 50f 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 50f 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 OLL. As a result, even if the center of the asphalt finisher 100 is slightly offset from the center line CL1 of the road to be paved, the paving material can be properly spread and leveled on the road surface to be paved.

[0126] Incidentally, when the center of the asphalt finisher 100 coincides with the center line CL1, the length from the center line CL1 to the left edge of the road is L1, and the length from the center line CL1 to the right edge of the road is also L1. Therefore, the screed control unit 50f should perform expansion and contraction control so that the length from the center of the asphalt finisher 100 to the right side plate 40R and the left side plate 40L is L1.

[0127] However, in the case of the asphalt finisher 100, when the movement control unit 50e performs automatic control, the center of the asphalt finisher 100 may deviate from the center line CL1. For example, if the road is curved, and there is a delay in the timing of the movement control unit 50e changing the steering angle in the automatic control of the tractor 1, the center of the asphalt finisher 100 will deviate from the center line CL1. In this case, for example, the center of the asphalt finisher 100 may move along the path CL2.

[0128] In this case, the screed control unit 50f controls the extension and retraction of the left retractable screed 31L so that the length from the center of the asphalt finisher 100 to the left side plate 40L is L3.

[0129] The screed control unit 50f needs to control the extension and retraction of the right retractable screed 31R so that the length from the center of the asphalt finisher 100 to the right side plate 40R is L2. However, when the right retractable screed 31R is shortened so that the length from the center of the asphalt finisher 100 to the right side plate 40R is L2, the right side plate 40R may come into contact with the screw SC.

[0130] Figure 6 shows the positional relationship between the left side plate 40L and the screw SC according to this embodiment. Figure 6 shows the positional relationship between the screw SC, which has the first left extension screw SCLE1 connected to the left main screw SCLM, and the left side plate 40L, but the positional relationship between the screw SC and the right side plate 40R is similar.

[0131] In the example shown in Figure 6, the direction of travel is 5001. The left main screw SCLM and the first left extension screw SCLE1 are rotated in the direction of arrow 6001 by control of the screw control device 56, thereby pushing the pavement material toward the shoulder (the direction in which the target line OLL exists).

[0132] The screed control unit 50f then controls the extension and retraction of the left screed extension cylinder 27L so that the left side plate 40L aligns with the left target line OLL. The extension and retraction mold board 41 is assumed to extend and retract according to the extension and retraction control by the left screed extension and retraction cylinder 27L, and its description is omitted.

[0133] If the left side plate 40L is detected to be shifted to the right of the left target line OLL, the screed control unit 50f controls the left screed extension cylinder 27L to extend it, moving the left side plate 40L in the direction of the left arrow 6002.

[0134] Similarly, if the left side plate 40L is detected to be shifted to the left of the left target line OLL, the screed control unit 50f controls the left screed extension cylinder 27L to retract, moving the left side plate 40L in the direction of the right arrow 6003. However, if the left side plate 40L moves too far in the direction of the right arrow 6003, the left side plate 40L will come into contact with the end of the first left extension screw SCLE1.

[0135] Therefore, the screed control unit 50f according to this embodiment controls the length of the retractable screed 31 (an example of a screed device) in the vehicle width direction so as not to fall below a predetermined length, so that the left side plate 40L does not come into contact with the first left extension screw SCLE1.

[0136] Returning to Figure 5, when the screed control unit 50f controls the retractable screed 31 to retract, it suppresses the control to retract the screed 31 when the length of the retractable screed 31 in the vehicle width direction is a predetermined length. As a result, the right side plate 40R moves according to the movement line 5011 which extends beyond the right target line OLR towards the shoulder. This causes the pavement material to extend onto the shoulder, but prevents the right side plate 40R from contacting the screw SC. Therefore, by performing the above-described control, the controller 50 can prevent the right side plate 40R from contacting the screw SC, thereby improving safety.

[0137] The controller 50 according to this embodiment can perform various controls when suppressing the control of retracting the retractable screed 31.

[0138] For example, the movement control unit 50e may perform a control to reduce the speed of the tractor 1 of the asphalt finisher 100 when the screed control unit 50f is suppressing the control to retract the retractable screed.

[0139] In other words, when the screed control unit 50f suppresses the control to retract the retractable screed 31, the movement control unit 50e estimates that the center of the asphalt finisher 100 is misaligned with the center line of the road. Then, the movement control unit 50e controls the tractor 1 to reduce its speed in order to correct this misalignment. After reducing the speed, the movement control unit 50e can correct the direction of movement of the asphalt finisher 100 and restart the control to extend or retract the retractable screed 31 so that the side plates 40 align with the target line. Therefore, the direction of movement can be corrected twice as many times as the speed is reduced, which can improve the accuracy of the road surface paving. Furthermore, if the movement control unit 50e recognizes that it is difficult to correct the direction of movement or that an abnormality has occurred after reducing the speed of the tractor 1, it may stop the tractor 1.

[0140] Another example is that the communication control unit 50a may transmit information to an external device indicating that the screed control unit 50f has suppressed the control to retract the retractable screed 31. For example, the communication control unit 50a may transmit information indicating that the control to retract the retractable screed 31 has been suppressed to a road roller located behind the asphalt finisher 100 in the direction of travel. This allows the road roller to perform control based on this information. Alternatively, the communication control unit 50a may transmit information indicating that the control to retract the retractable screed 31 has been suppressed to the portable communication devices of nearby workers. By transmitting this information, subsequent road rollers or workers can follow up. For example, a worker can return any paving material that has spilled onto the shoulder back onto the road surface. Therefore, by transmitting the above-mentioned information, the accuracy of road surface paving can be improved. Furthermore, the communication control unit 50a may transmit information indicating that the control to retract the retractable screed 31 has been suppressed to a management server that manages the work history. This allows this embodiment to manage the work history of the asphalt finisher 100.

[0141] <Explanation of control procedures in automatic movement control using an asphalt finisher> Figure 7 is a flowchart showing the control of the asphalt finisher 100 by the controller 50 according to this embodiment. In the example shown in Figure 7, the length of the screw SC has already been registered in the screw length storage unit 48b.

[0142] First, the acquisition unit 50c of the controller 50 acquires a predetermined length based on the length of the screw SC from the screw length storage unit 48b of the auxiliary storage device 48 before performing automatic control (S7001).

[0143] Next, before performing automatic control, the acquisition unit 50c acquires schedule information from the schedule information storage unit 48a of the auxiliary storage device 48 (S7002).

[0144] The movement path calculation unit 50d calculates the movement path of the asphalt finisher 100 according to the schedule information (S7003).

[0145] Then, the movement control unit 50e starts movement control to move according to the calculated movement path (S7004).

[0146] The acquisition unit 50c acquires position information from the GPS module 54 and also acquires measurement information from the forward monitoring device 51F, the rear monitoring device 51, the driving speed sensor 47, and the screed length detection device 57 (S7005).

[0147] The movement control unit 50e performs movement control to move according to the movement path based on the position information and the measurement information from the forward monitoring device 51F, the rear monitoring device 51, and the travel speed sensor 47 (S7006).

[0148] The screed control unit 50f determines whether the side plate 40 is deviating from the target line based on the measurement information from the screed length detection device 57 and the position of the target line indicated by the schedule information (S7007). If it is determined that the side plate 40 is not deviating from the target line (S7007: No), no extension or retraction control is performed, and the process proceeds to S7011.

[0149] If the side plate 40 is determined to be deviating from the target line (S7007: Yes), the screed control unit 50f determines whether the extension / retraction control to correct the deviation is a control that shortens the length of the extension / retraction screed 31 in the vehicle width direction to a predetermined length (S7008).

[0150] If it is determined that the control is not intended to shorten the length of the retractable screed 31 in the vehicle width direction to a predetermined length (S7008: No), the screed control unit 50f performs extension / retraction control to correct the misalignment (S7009).

[0151] On the other hand, if it is determined that the control is to shorten the length of the retractable screed 31 in the vehicle width direction to a predetermined length (S7008: Yes), the shortening control is stopped (S7010).

[0152] Subsequently, the movement control unit 50e determines whether the movement along the movement path has been completed (S7011). If it determines that the movement has not been completed (S7011: No), the process returns to S7005.

[0153] On the other hand, if the movement control unit 50e determines that movement along the movement path has been completed (S7011: Yes), it terminates the process.

[0154] In this embodiment, the controller 50 can control the extension and retraction of the retractable screed 31 to match the width of the road when performing movement control. If it is necessary to shorten the length of the retractable screed 31 in the vehicle width direction to a predetermined length, the controller 50 can stop this shortening control to prevent the side plate 40 from contacting the screw SC.

[0155] (modified version) In the above-described embodiment, the case in which the controller 50 controls the extension and retraction of the retractable screed 31 when performing automatic movement control of the asphalt finisher 100 was explained. However, the suppression of the retraction control of the retractable screed 31 is not limited to when automatic movement control is performed as in the above-described embodiment, but may also be performed when an operation to retract the retractable screed 31 is received from the operator. Therefore, in the modified example, the case in which an operation to retract the retractable screed 31 is received from the operator will be explained.

[0156] The asphalt finisher 100 in this modified model moves according to the steering of the operator seated in the driver's seat 1S. Furthermore, the asphalt finisher 100 in this modified model controls the extension and retraction of the telescopic screed 31 according to the operator's commands.

[0157] Figure 8 shows a rear view of the asphalt finisher 100. In the example shown in Figure 8, the input unit 55L receives an operation from the operator to extend the left retractable screed 31L to the left side in the vehicle width direction relative to the main screed 30. The input unit 55R receives an operation from the operator to extend the right retractable screed 31R to the right side in the vehicle width direction relative to the main screed 30. The input units 55L and 55R output the information of the received operation to the controller 50.

[0158] As a result, the screed control unit 50f of the controller 50 controls the extension and retraction of the retractable screed 31 according to the received operation information.

[0159] Furthermore, when the screed control unit 50f controls the retractable screed 31 to retract based on an operation input from the input unit 55L or input unit 55R, it suppresses the control to retract the retractable screed 31 when the length of the retractable screed 31 in the vehicle width direction is a predetermined length.

[0160] In this modified version, the screed control unit 50f performs the control described above, which prevents the screw SC from coming into contact with the side plate 40 even when the operator controls the extension and retraction of the retractable screed 31. Therefore, the asphalt finisher 100 according to this modified version can achieve improved safety.

[0161] This modified example describes the case where the input device that receives operations from the operator consists of input unit 55L and input unit 55R. However, this modified example is not limited to the example that includes input unit 55L and input unit 55R. For example, one input device may control the extension and retraction of the left retractable screed 31L and the right retractable screed 31R. The input device is not limited to the example where it is installed near the rear of the asphalt finisher 100, but may be installed in the driver's seat 1S, or it may be a detachable device that performs wireless communication.

[0162] <effect> The controller 50 of the asphalt finisher 100 according to the above-described embodiment and modified example has the above-described configuration, and when controlling the extension and retraction of the retractable screed 31 to match the width of the road surface, it controls the extension and retraction of the retractable screed 31 so that the length of the retractable screed 31 in the vehicle width direction does not fall below a predetermined length based on the screw SC. As a result, it is possible to prevent the side plate 40 provided at the far end of the retractable screed 31 from coming into contact with the screw SC, thereby improving safety.

[0163] Furthermore, the predetermined length is set based on the total length obtained by adding the length of the extension screw to the length of the main screw when an extension screw is connected. For example, when the asphalt finisher 100 is performing construction, if the length of the screw SC is changed according to the width of the road, control is performed to prevent the side plate 40 from coming into contact with the screw SC after the length has been changed. Therefore, even if the length of the screw SC is changed, contact with the side plate 40 is suppressed, thereby improving safety.

[0164] 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.

[0165] 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]

[0166] 100 Asphalt Finisher SCLM Left Main Screw SCRM Right Main Screw SCLE1 1st left extension screw SCRE1 First right extension 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 Screw length memory section 50 controllers 50a Communication Control Unit 50b Setting section 50c acquisition part 50d Movement path calculation unit 50e Movement Control Unit 50f Screed Control Unit 51F Forward monitoring device 51B Rear monitoring device 52 Drive System Controller 53 Communication equipment 54 GPS modules 55 Scred control device 56 Screw control device

Claims

1. Tractor and, A hopper installed on the front side of the aforementioned tractor, A conveyor that transports 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, When controlling the screed device to shorten it to correspond to the width of the road surface on which the paving material is spread, the control to shorten the screed device is suppressed when the length of the screed device in the vehicle width direction is a predetermined length. The screw can be connected to one or more of several types of expansion screws. The predetermined length when the expansion screw is connected to the screw is a length determined based on information identifying the connected expansion screw. The information identifying the aforementioned expansion screw is information provided on the expansion screw and read by a predetermined reader. Asphalt finisher.

2. A tractor and A hopper installed on the front side of the aforementioned tractor, A conveyor that transports 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, When controlling the screed device to shorten it to correspond to the width of the road surface on which the paving material is spread, the control to shorten the screed device is suppressed when the length of the screed device in the vehicle width direction is a predetermined length. The screw can be connected to one or more of several types of expansion screws. The predetermined length when the expansion screw is connected to the screw is a length determined based on information identifying the connected expansion screw. The information identifying the expansion screw is information read from the RFID unit provided on the expansion screw. Asphalt finisher.

3. When controlling the screed device to retract based on the detection result of the length of the screed device in the vehicle width direction to correspond to the width of the road surface on which the paving material is spread, the control to retract the screed device is suppressed when the length of the screed device in the vehicle width direction is a predetermined length. The asphalt finisher according to claim 1.

4. The screed device further has an input device for inputting the extension and retraction operation, When controlling the retraction of the screed device based on an operation input from the input device, the control to retract the screed device is suppressed if the length of the screed device in the vehicle width direction is the predetermined length. The asphalt finisher according to claim 1.

5. When the control to retract the screed device is suppressed, the system is configured to reduce the speed of the asphalt finisher. The asphalt finisher according to any one of claims 1 to 4.

6. The system is configured to transmit information to an external device indicating that the control to retract the screed device has been suppressed. The asphalt finisher according to any one of claims 1 to 5.

7. The predetermined length is set based on the length of the screw in the vehicle width direction. The asphalt finisher according to any one of claims 1 to 6.

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