Asphalt paver

Abstract

The present application provides a kind of asphalt rolling machine, can make the flow of working oil stable, and can be with appropriate speed extension and contraction width of screed.The asphalt rolling machine (100) is equipped with the screed (3) that is moved while paving paving material (PV).The asphalt rolling machine (100) is equipped with: screed extension cylinder (26), with the supply of working oil and extension, make the side frame (32) of the paving limit of screed (3) move;And hydraulic pump (25), working oil is supplied to screed extension cylinder (26).Switching valve (33) and proportional valve (36) are arranged on the path between hydraulic pump (25) and screed extension cylinder (26), the switching valve (33) switches the supply object of working oil, and the proportional valve (36) adjusts the flow of working oil.

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2024-211156, filed on December 4, 2024. The entire contents of that Japanese application are incorporated herein by reference.

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

[0003] In recent years, an asphalt trolley has been developed that automatically controls the width of the screed based on the evenly paved surface. However, if the screed's telescopic cylinder, which moves the screed's width, is directly controlled automatically at the same speed as when manually operated, the telescopic speed can sometimes be too fast. This can reduce the accuracy of aligning the screed's width to the target position. Conversely, if the telescopic cylinder's telescopic speed is slowed down to improve control accuracy, the operation will be slower when manually operated.

[0004] Therefore, it is possible to make the extension speed of the screed variable. For example, Patent Document 1 discloses an asphalt screed in which the paving boundary of the surface being paved is detected by a detection sensor unit provided on the screed, and the extension speed of the screed is adjusted to restore the offset when the outer end of the screed is offset relative to the paving boundary.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-155970 However, the technology described in Patent Document 1 uses PWM control to gradually increase the extension and retraction speed of the hydraulic cylinder by opening and closing the hydraulic switching valve for extension and retraction, thereby controlling the recovery of the offset of the outer end of the expansion plate. Even with high extension and retraction speeds, the problem of not being able to accurately position the width of the leveling machine remains.

[0006] Furthermore, as a structure that allows for variable cylinder extension and retraction speed, a proportional valve capable of adjusting the flow rate of the working oil could be considered instead of a switching valve. However, when only a proportional valve is used, the flow rate of the working oil fluctuates significantly during extension and retraction switching, and it takes time for the flow rate to stabilize. Summary of the Invention

[0007] This invention provides an asphalt roller that can stabilize the flow rate of working oil and can extend and retract the width of the screed at an appropriate speed.

[0008] According to one aspect of the present invention, an asphalt tumbler is provided, comprising a leveling machine that moves in a paving direction while spreading paving material evenly. The asphalt tumbler includes: a leveling machine telescopic cylinder that extends and retracts with the supply of working oil, causing a side frame that serves as the spreading limit of the leveling machine to move; and a hydraulic pump that supplies the working oil to the leveling machine telescopic cylinder. A switching valve and a proportional valve are provided in the path between the hydraulic pump and the leveling machine telescopic cylinder, the switching valve switching the target of the working oil supply, and the proportional valve adjusting the flow rate of the working oil.

[0009] Invention Effects One method involves an asphalt trolley that can stabilize the flow of working oil and can extend and retract the width of the trolley at an appropriate speed. Attached Figure Description

[0010] Figure 1 This is a side view of the asphalt roller involved in the implementation method.

[0011] Figure 2 This is a top view of an asphalt roller.

[0012] Figure 3 This is a block diagram representing a structural example of an automatic control system.

[0013] Figure 4 This is a top-down view showing the construction site of an asphalt roller passing through the road being constructed.

[0014] Figure 5 This is a diagram showing the hydraulic circuit relative to the telescopic cylinder of the left leveling machine.

[0015] Figure 6 This is a flowchart illustrating the control method of the telescopic cylinder of the leveling machine.

[0016] In the diagram: 3-leveling machine, 25-hydraulic pump, 26-leveling machine telescopic cylinder, 32-side frame, 33-switching valve, 36-proportional valve, 37-pressure compensation valve, 38-drive switching valve, 50-controller, 100-asphalt roller, 261a-base end side oil chamber, 261b-rod side oil chamber, PV-paving material. Detailed Implementation

[0017] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same structural parts are labeled with the same symbols, and sometimes repeated descriptions are omitted.

[0018] Figure 1 This is a side view of the asphalt roller 100 according to the embodiment. Figure 2This is a top view of the asphalt roller 100. The asphalt roller 100 described in this embodiment is a wheeled asphalt roller, which mainly includes a tractor 1, a hopper 2, and a leveling machine 3. Hereinafter, the direction of the hopper 2 (+X direction) as viewed from the perspective of the tractor 1 will be defined as the front, and the direction of the leveling machine 3 (-X direction) as viewed from the tractor 1 will be defined as the rear.

[0019] The traction unit 1 is a mechanism for moving the asphalt trolley 100. The traction unit 1 uses a rear-wheel travel hydraulic motor to rotate the rear wheel 5, and uses a front-wheel travel hydraulic motor to rotate the front wheel 6, thereby moving the asphalt trolley 100. Both the rear-wheel travel hydraulic motor and the front-wheel travel hydraulic motor receive working oil from a hydraulic pump to rotate. Alternatively, one of the rear wheel 5 and the front wheel 6 can be a driven wheel. Furthermore, the asphalt trolley 100 can also be a tracked asphalt trolley by replacing the rear wheel 5 and the front wheel 6 with a left track and a right track, respectively.

[0020] The asphalt trolley 100 includes a control unit, namely a controller 50, for controlling various structures. The controller 50 is, for example, a microcomputer including a processor, memory (volatile and non-volatile memory devices, etc.), and input / output interfaces, and is mounted on the traction machine 1. The functions of the controller 50 are implemented by the processor executing programs stored in the non-volatile memory device. However, the functions of the controller 50 can be implemented not only by software, but also by hardware, or a combination of hardware and software.

[0021] Hopper 2 is a mechanism for receiving paving materials. In the example shown, hopper 2 is positioned in front of the tractor 1 and opens and closes in the vehicle width direction (Y-axis direction) via a hopper cylinder. Typically, the asphalt roller 100 receives paving materials (e.g., asphalt mixture) from the dump truck's cargo compartment when hopper 2 is fully open. The dump truck is an example of a transport vehicle for carrying paving materials. Figure 1 and Figure 2 The diagram illustrates the fully open state of hopper 2. If the material in hopper 2 decreases, hopper 2 closes, and the material near the inner wall of hopper 2 concentrates in the center. This allows the conveyor CV, located in the center of hopper 2, to supply material to the rear of the traction machine 1. The material is supplied to the rear of the traction machine 1 via screw SC along the vehicle width direction from the rear of the traction machine 1 and the front of the leveler 3. In the example diagram, screw SC is in a state where extended screws are connected to the left and right sides. For ease of understanding, Figure 1 and Figure 2 The diagram of the paving material in hopper 2 is omitted. The paving material PV spread by the screw SC is represented by a sparse dot pattern, and the newly laid paving body NP is represented by a dense dot pattern.

[0022] The leveling machine 3 is a mechanism for spreading paving material PV evenly. The leveling machine 3 according to the embodiment includes a front leveling machine 30 and a rear leveling machine 31. The front leveling machine 30 includes a left front leveling machine 30L and a right front leveling machine 30R. The rear leveling machine 31 is a leveling machine capable of extending and retracting along the vehicle width direction, including a left rear leveling machine 31L and a right rear leveling machine 31R. The rear leveling machine 31 extends and retracts in the vehicle width direction via a leveling machine telescopic cylinder 26. Specifically, the left rear leveling machine 31L extends and retracts in the vehicle width direction using the left leveling machine telescopic cylinder 26L. The right rear leveling machine 31R extends and retracts in the vehicle width direction using the right leveling machine telescopic cylinder 26R. Furthermore, the leveling machine 3 is a floating leveling machine towed by a tractor 1 and is connected to the tractor 1 via a leveling arm 3A. The leveling boom 3A includes a left leveling boom 3AL disposed on the left side of the tractor 1 and a right leveling boom 3AR disposed on the right side of the tractor 1.

[0023] A plow plate 43 is installed at the front of the leveling machine 3. The plow plate 43 adjusts the amount of paving material PV remaining in front of the leveling machine 3. The paving material PV reaches the bottom of the leveling machine 3 through the gap between the lower end of the plow plate 43 and the roadbed BS.

[0024] A pair of side frames 32 (left side frame 32L, right side frame 32R) are installed at both ends of the rear screed 31 in the width direction to limit the evenness of the paving material PV. The left side frame 32L extends for a predetermined length along the front-rear direction at the left end of the rear screed 31. The left side frame 32L is displaced along the vehicle width direction by the extension and retraction of the left screed telescopic cylinder 26L. The right side frame 32R extends for a predetermined length along the front-rear direction at the right end of the rear screed 31. The right side frame 32R is displaced along the vehicle width direction by the extension and retraction of the right screed telescopic cylinder 26R.

[0025] Furthermore, the tractor 1 is equipped with an information acquisition device 51, an on-board display device 52, a control device 53, and a leveling machine telescopic control device 54.

[0026] Information acquisition device 51 acquires road-related information concerning the construction object and outputs the acquired information to controller 50. Road-related information includes, for example, the road width, changes in curvature in transition sections (boomerang sections), and curvature in circular arc sections. Information acquisition device 51 may include, for example, a forward monitoring device 51F, a rear monitoring device 51B, a driving speed sensor 51S, a positioning device 51P, and a communication device 51T.

[0027] The forward monitoring device 51F acquires information about the front of the asphalt trolley 100. The forward monitoring device 51F can utilize a camera or LiDAR with a monitoring range RF located in front of the tractor 1. The forward monitoring device 51F is mounted in the center of the tractor 1 (e.g., the front center of the cover covering the engine compartment located behind the hopper 2). However, the forward monitoring device 51F can also be mounted in other parts of the asphalt trolley 100. The forward monitoring device 51F can be configured by combining multiple cameras and multiple LiDARs. For example, the LiDAR may include a right front LiDAR mounted on the right side of the front of the tractor 1 and a left front LiDAR mounted on the left side of the front of the tractor 1.

[0028] The rear monitoring device 51B acquires information about the rear of the asphalt tumbler 100. The rear monitoring device 51B can utilize cameras and LiDARs that monitor the area RB located behind the tumbler 3. The rear monitoring device 51B is mounted on the guide rail 1G, which functions as a handrail. However, the rear monitoring device 51B can be mounted under the driver's seat 1S or at other locations on the asphalt tumbler 100. Furthermore, the rear monitoring device 51B can be configured by combining multiple cameras and multiple LiDARs. For example, the multiple LiDARs may include a right rear LiDAR mounted on the right side of the rear end of the tractor 1 and a left rear LiDAR mounted on the left side of the rear end of the tractor 1.

[0029] Furthermore, the information acquisition device 51 may include a side monitoring device for monitoring the side of the asphalt roller 100. In this case, the side monitoring device includes a left side monitoring device and a right side monitoring device. The left side monitoring device is, for example, a camera or LiDAR monitoring the area to the left of the tractor 1, and is mounted on the left end of the upper surface of the tractor 1. The right side monitoring device is, for example, a camera or LiDAR monitoring the area to the right of the tractor 1, and is mounted on the right end of the upper surface of the tractor 1.

[0030] The camera can be either a monocular camera or a stereo camera, capturing images of the surroundings to obtain video information. A LiDAR, for example, measures the distances between multiple points within the monitoring range and the LiDAR. However, one or both of the front monitoring device 51F and the rear monitoring device 51B are not limited to a camera or a LiDAR; they can also be millimeter-wave radar, lidar, a laser scanner, a distance-image camera, or a laser rangefinder, etc. The same applies to the side monitoring device.

[0031] The forward monitoring device 51F is preferably configured to detect a monitoring range RF that includes the roadbed BS and the above-ground structures AP located outside the roadbed BS. This is to obtain information related to the width of the road to be constructed. The same applies to the monitoring range of the lateral monitoring device. In the example shown, the monitoring range RF has a width greater than the width of the roadbed BS. The above-ground structures AP are, for example, paving frames, L-shaped side channels, curb stones, or existing paving structures.

[0032] The rear monitoring device 51B is preferably configured to detect a monitoring range RB that includes the newly installed pavement NP and the ground features AP located outside the newly installed pavement NP. This is to obtain information related to the width of the newly installed pavement NP. In the example shown, the monitoring range RB has a width greater than the width of the newly installed pavement NP.

[0033] The travel speed sensor 51S detects the travel speed of the asphalt roller 100. For example, the travel speed sensor 51S is a wheel speed sensor and is configured to detect the rotational angular velocity and rotational angle of the rear wheel 5, as well as the travel speed and travel distance of the asphalt roller 100.

[0034] The positioning device 51P is configured to measure the position of the asphalt roller 100. For example, the positioning device 51P is a GNSS compass and is configured to measure the position and orientation of the asphalt roller 100. The GNSS compass of the positioning device 51P includes a left GNSS receiver 51PL mounted on the rod PL at the rear end of the left leveling arm 3AL and a right GNSS receiver 51PR mounted on the rod PL at the rear end of the right leveling arm 3AR.

[0035] However, the positioning device 51P can be a total station. In this case, a reflecting prism serving as the target of the total station is installed at the front end of the pole PL. The main body of the total station, positioned around the asphalt roller 100, is connected to the controller 50 via wireless communication. That is, the main body of the total station sends information related to the position of the derived target to the controller 50.

[0036] The communication device 51T enables information communication between the asphalt roller 100 and equipment located outside the asphalt roller 100. In the example shown, the communication device 51T is located in front of the driver's seat 1S and is configured to perform communication via mobile communication networks, short-range wireless communication networks, or satellite communication networks.

[0037] Furthermore, the information acquisition device 51 may also include a rudder angle sensor 51R for detecting the rudder angle of the asphalt roller 100 (see reference). Figure 3 ) and the leveling machine position sensor 51C for calculating the position of the side frame 32 (reference) Figure 3 )wait.

[0038] Furthermore, the information acquisition device 51 may include a monitoring device installed at the construction site or a monitoring device mounted on an aircraft flying above the asphalt roller 100. The monitoring device installed at the construction site may be, for example, a camera or LiDAR mounted on the front end of a pole installed along the road surface of the construction object. The monitoring device mounted on the aircraft may be, for example, a camera or LiDAR mounted on a multi-rotor aircraft (drone) or airship.

[0039] The vehicle-mounted display device 52 is configured to display information related to the asphalt tumbler 100. In the embodiment described, the vehicle-mounted display device 52 is a liquid crystal display located in front of the driver's seat 1S. However, the vehicle-mounted display device 52 may also be located at the left or right end of the tumbler 3, etc.

[0040] The control device 53 is a device for operating the asphalt roller 100. The control device 53 according to the embodiment extends and retracts the front wheel control cylinder located near the front axle. Specifically, the control device 53 includes a control solenoid valve that controls the flow rate of working oil from the hydraulic pump to the front wheel control cylinder and the flow rate of working oil discharged from the front wheel control cylinder. The control solenoid valve controls the flow of working oil in the front wheel control cylinder according to the rotation of the steering wheel SH (handle), which is the operating device. Furthermore, the control solenoid valve is configured to control the flow of working oil in the front wheel control cylinder independently of the rotation of the steering wheel SH, based on control commands from the controller 50. That is, the controller 50 can automatically control the operation of the asphalt roller 100 regardless of whether the operator operates the steering wheel SH.

[0041] In the case where the asphalt tumbler 100 is a tracked asphalt tumbler, the operating device 53 is configured to independently control the left and right pairs of tracks. Specifically, the operating device 53 includes a left solenoid control valve that controls the flow of working oil from the hydraulic pump to the left travel hydraulic motor for rotating the left track, and a right solenoid control valve that controls the flow of working oil from the hydraulic pump to the right travel hydraulic motor for rotating the right track. Furthermore, the left solenoid control valve controls the flow of working oil in the left travel hydraulic motor based on the amount of operation (tilt angle) of the left operating lever, which is the operating device for operating the left track. The left solenoid control valve is configured to control the flow of working oil in the left travel hydraulic motor regardless of whether the operator operates the left operating lever, based on control commands from the controller 50. Similarly, the right solenoid control valve controls the flow of working oil in the right travel hydraulic motor based on the amount of operation (tilt angle) of the right operating lever, which is the operating device for operating the right track. Furthermore, the right solenoid control valve is configured to control the flow of working oil in the right travel hydraulic motor regardless of whether the operator operates the right control lever, based on control commands from the controller 50.

[0042] The leveling machine telescopic control device 54 controls the leveling machine telescopic cylinder 26 to extend and retract the rear leveling machine 31. Specifically, the leveling machine 3 has a switching valve 33 that controls the flow direction of the working oil from the hydraulic pump to the leveling machine telescopic cylinder 26, and a control valve unit 35 that controls the flow rate of the working oil (see also...). Figure 5 The leveling machine telescopic control device 54 controls the driving of these switching valves 33 and control valve units 35.

[0043] The leveling machine telescopic control device 54 controls the flow of working oil in the leveling machine telescopic cylinder 26 based on the opening and closing operations of the leveling machine telescopic switch (not shown), which serves as an operating device. Furthermore, the leveling machine telescopic control device 54 is configured to control the flow of working oil in the leveling machine telescopic cylinder 26 independently of the operation of the leveling machine telescopic switch, based on control commands from the controller 50. That is, the controller 50 can automatically control the telescopic amount of the rear leveling machine 31 regardless of whether the operator operates the leveling machine telescopic switch. The control of this leveling machine telescopic cylinder 26 will be described in detail later.

[0044] Furthermore, the switching valve 33 includes a left switching valve 33L and a right switching valve 33R, which, under the control of the leveling machine extension control device 54, control the extension and retraction of the left rear leveling machine 31L and the right rear leveling machine 31R, respectively. The control valve unit 35 includes a left control valve unit 35L and a right control valve unit 35R, which, under the control of the leveling machine extension control device 54, control the flow rate of working oil for the left rear leveling machine 31L and the right rear leveling machine 31R, respectively. Specifically, the left switching valve 33L and the left control valve unit 35L control the flow of working oil from the hydraulic pump to the left leveling machine extension cylinder 26L based on the operation of the left leveling machine extension switch (not shown), which serves as an operating device. Furthermore, the left switching valve 33L and the left control valve unit 35L control the flow of working oil from the hydraulic pump to the left leveling machine extension cylinder 26L based on control commands from the controller 50, regardless of whether the left leveling machine extension switch is operated. The same applies to the right solenoid control valve.

[0045] Next, refer to Figure 3 The structure of the automatic control system DS mounted on the asphalt roller 100 will be described. Figure 3 This is a block diagram representing a structural example of an automatic control system (DS).

[0046] The automatic control system DS mainly consists of a controller 50, a front monitoring device 51F, a rear monitoring device 51B, a driving speed sensor 51S, a positioning device 51P, a rudder angle sensor 51R, a leveling machine position sensor 51C, a communication device 51T, an on-board display device 52, a control device 53, and a leveling machine telescopic control device 54.

[0047] exist Figure 3 In the example shown, the controller 50 includes a target calculation unit 50a, an operation control unit 50b, a side frame target track calculation unit 50c, and a leveling machine control unit 50d as functional modules.

[0048] The target calculation unit 50a calculates the target used by the operation and control unit 50b. The target used by the operation and control unit 50b is, for example, the main target track that a predetermined point of the asphalt roller 100 should follow. Strictly speaking, the target track is a two-dimensional arrangement of multiple target positions. Alternatively, the target used by the operation and control unit 50b can be a target position that a predetermined point of the asphalt roller 100 should reach after a predetermined time. The predetermined time is, for example, several milliseconds, tens of milliseconds, hundreds of milliseconds, or several seconds.

[0049] The designated point of the asphalt roller 100 is set on the front-rear axis of the traction machine 1, preferably located further forward than the leveling machine 3. For example, the designated point is set at the center, front center, or rear center of the traction machine 1, the hopper 2, or the leveling machine 3. In this embodiment, the asphalt roller 100 has a designated point set at the center of the leveling machine 3 (front leveling machine 30) in the width direction.

[0050] The target calculation unit 50a calculates, for example, the main target track that the leveling machine 3 should follow at a specified point in the paving direction of the asphalt tumbler 100, based on road-related information such as construction data (design data). Typically, the main target track is calculated before the asphalt tumbler 100 begins to move. Therefore, the main target track can be calculated by a server or the like located in a management center outside the asphalt tumbler 100 and then sent to the controller 50 via communication.

[0051] The target calculation unit 50a can calculate the main target position as the location that the leveling machine 3 should reach after a specified time. At this time, the main target position is repeatedly calculated at a specified control cycle during the travel of the asphalt roller 100. For example, when the asphalt roller 100 is traveling on a straight section of the road to be constructed, the target calculation unit 50a can calculate the main target position based on information obtained from the forward monitoring device 51F, using the center point in the width direction of the road to be constructed that is further ahead of the current position of the leveling machine 3 at a specified distance. The specified distance is, for example, several centimeters to tens of centimeters. The target calculation unit 50a can calculate the main target position without obtaining design data. However, the target calculation unit 50a can calculate the main target position based on design data and information obtained from the forward monitoring device 51F. For example, the target calculation unit 50a can correct the target position calculated based on the design data based on information obtained from the forward monitoring device 51F. Furthermore, the target calculation unit 50a can use information obtained from the rear monitoring device 51B to correct the main target position.

[0052] The control unit 50b automatically controls the operation of the asphalt roller 100, providing operational support for the operator.

[0053] In this embodiment, the control unit 50b outputs control commands to the control device 53 so that the predetermined point of the leveling machine 3 follows the main target track calculated by the target calculation unit 50a. Specifically, the control unit 50b calculates the current position of the predetermined point of the leveling machine 3 based on the output of the positioning device 51P. Furthermore, for example, if it is determined that the predetermined point has deviated from the main target track to the right, the control unit 50b outputs control commands to the control device 53 to move the traction machine 1 to the left. Similarly, if it is determined that the predetermined point has deviated from the main target track to the left, the control unit 50b outputs control commands to the control device 53 to move the asphalt roller 100 to the right.

[0054] Alternatively, the control unit 50b can output control commands to the control device 53 in a manner that causes the designated point of the leveling machine 3 to align with the target position calculated by the target calculation unit 50a. In this case, the control unit 50b can derive the current position of the designated point of the leveling machine 3 based on the output of the positioning device 51P, or it can derive the current position of the designated point of the leveling machine 3 based on the output of at least one of the rear monitoring device 51B and the front monitoring device 51F.

[0055] Next, refer to Figure 4 The function of moving the asphalt roller 100 along the target track is explained. Figure 4 This is a top view of the construction site of an asphalt roller 100, representing the straight section SP1, the curved section LC (left curve), and the straight section SP2 of road RD, which passes through the construction object. Figure 4 In this diagram, symbol 100a represents the asphalt roller 100 at the start of construction, i.e., at moment 1. Symbol 100b represents the asphalt roller 100 at moment 2, after a predetermined time elapsed from moment 1. Similarly, symbol 100c represents the asphalt roller 100 at moment 3, after a predetermined time elapsed from moment 2; symbol 100d represents the asphalt roller 100 at moment 4, after a predetermined time elapsed from moment 3; and symbol 100e represents the asphalt roller 100 at moment 5, after a predetermined time elapsed from moment 4. Furthermore, for clarity, Figure 4 The simplified diagram shows the asphalt roller 100, including the tractor 1, the front leveler 30, the left rear leveler 31L, and the right rear leveler 31R.

[0056] At the start of construction, i.e., at moment 1, the target calculation unit 50a of controller 50 calculates the main target track TPS that the specified point Q of leveling machine 3 should follow. Figure 4 In this model, point Q is represented by a triangle, and the main target trajectory TPS is represented by a dashed line. For example, the target calculation unit 50a, referencing design data, derives the main target trajectory TPS based on the left and right boundary lines of the road RD of the construction object. Furthermore, in... Figure 4 In the diagram, the centerline CP of road RD is represented by a dashed line. The main target track TPS can be generated by dividing the area of ​​the road surface that will be evenly spread by the leveling machine 3 into two equal parts. The area of ​​the road surface is, for example, the area of ​​the road surface that is evenly spread when the asphalt roller 100 advances a specified distance.

[0057] The control unit 50b of the controller 50 calculates the current position of the designated point Q of the leveling machine 3 based on the output of the positioning device 51P. Furthermore, the control unit 50b operates the asphalt roller 100 in a manner that aligns the actual position coordinates of the designated point Q with one of the position coordinates constituting the main target track TPS. Thus, the control unit 50b moves the designated point Q, which is located at point Qa at time 1, to point Qb at time 2, to point Qc at time 3, to point Qd at time 4, and to point Qe at time 5.

[0058] Furthermore, during the movement of the asphalt tumbler 100, the position of the left side frame 32L at the left end of the left rear screed 31L is controlled along the left side frame target track LTP calculated by the controller 50. Similarly, the position of the right side frame 32R at the right end of the right rear screed 31R is controlled along the right side frame target track RTP calculated by the controller 50.

[0059] Therefore, even when the traction machine 1 moves forward in a manner that follows the main target track TPS at a predetermined point Q, Figure 3 The side frame target track calculation unit 50c of the controller 50 shown also calculates the left frame target track LTP and the right frame target track RTP. The left frame target track LTP is basically calculated as the line corresponding to the left boundary line of the road RD. However, the left frame target track LTP can be calculated as a line different from the left boundary line depending on the capabilities of the asphalt roller 100 (e.g., the extension limit or extension speed of the leveler 3). Similarly, the right frame target track RTP is also basically calculated as the line corresponding to the right boundary line of the road RD. However, the right frame target track RTP can also be calculated as a line different from the left boundary line depending on the capabilities of the asphalt roller 100 (e.g., the extension limit or extension speed of the leveler 3).

[0060] The side frame target track calculation unit 50c can, for example, calculate the left frame target track LTP and the right frame target track RTP based on pre-acquired construction data and the position of the asphalt roller 100 measured by the positioning device 51P. In this case, the side frame target track calculation unit 50c can calculate the left frame target track LTP and the right frame target track RTP before construction. Furthermore, the side frame target track calculation unit 50c can also calculate the left frame target track LTP and the right frame target track RTP during construction based on detection information detected by the front monitoring device 51F or the side monitoring device. For example, the left frame target track LTP and the right frame target track RTP can be calculated based on information about the left and right boundary lines several meters ahead of the asphalt roller 100 detected by the front monitoring device 51F. Alternatively, the side frame target track calculation unit 50c can use construction data, the position of the asphalt roller 100, and the detection information detected by the front monitoring device 51F or the side monitoring device to calculate the left frame target track LTP and the right frame target track RTP.

[0061] The leveling machine control unit 50d of the controller 50 outputs control commands to the leveling machine telescopic control device 54 based on the left side frame target track LTP and the right side frame target track RTP calculated by the side frame target track calculation unit 50c, thereby controlling the operation of the leveling machine 3. The leveling machine control unit 50d outputs control commands in a manner that makes the left side frame 32L of the left rear leveling machine 31L consistent with the left side frame target track LTP, and the right side frame 32R of the right rear leveling machine 31R consistent with the right side frame target track RTP.

[0062] For example, if the left frame 32L may detach inward from the left frame target track LTP, the left frame 32L is extended to the left. Conversely, if the left frame 32L may detach outward from the left frame target track LTP, the left frame 32L is shortened to the right. Or, if the right frame 32R may detach inward from the right frame target track RTP, the right frame 32R is extended to the right. Conversely, if the right frame 32R may detach outward from the right frame target track RTP, the right frame 32R is shortened to the left. Thus, construction is carried out in a manner that makes the width of the side frame target tracks (left frame target track LTP, right frame target track RTP) consistent with the width of the newly installed paving body NP (width of the leveling machine 3).

[0063] Next, the specific structure of the hydraulic circuit having a switching valve 33 that extends and retracts the leveling machine telescopic cylinder 26 and a control valve unit 35 will be described. Figure 5 This is a diagram showing the hydraulic circuit of the 26L telescopic cylinder of the left leveling machine. The following is an example... Figure 5As shown, the hydraulic circuit for extending and retracting the left leveling machine telescopic cylinder 26L is used as an example for explanation. The hydraulic circuit for extending and retracting the right leveling machine telescopic cylinder 26R, which has the same structure, is omitted from the explanation.

[0064] The hydraulic circuit of the left leveling machine telescopic cylinder 26L includes a left switching valve 33L, a check valve 34, and a left control valve unit 35L, located between the hydraulic pump 25 (connected to the working oil storage tank 24) and the left leveling machine telescopic cylinder 26L. The left control valve unit 35L contains a bidirectional electromagnetic proportional flow valve (hereinafter referred to as proportional valve 36), a pressure compensation valve 37, and a drive switching valve 38. Furthermore, the hydraulic circuit connects the tank 27, which recovers the working oil discharged from the left leveling machine telescopic cylinder 26L, to the left switching valve 33L.

[0065] The left leveling machine telescopic cylinder 26L, connected to the hydraulic circuit, has a piston rod 262 that divides the internal space of the cylinder body 261 into a base-side oil chamber 261a and a rod-side oil chamber 261b. A left rear-side leveling machine 31L (see reference) is connected to the piston rod 262. Figure 2 The left leveling machine telescopic cylinder 26L, along with the supply of working oil from the left switching valve 33L to the base-side oil chamber 261a, causes the piston rod 262 to extend towards the front end. This causes the left side frame 32L of the left rear leveling machine 31L to displace outward in the width direction of the leveling machine 3. Conversely, the left leveling machine telescopic cylinder 26L, along with the supply of working oil from the left control valve unit 35L to the rod-side oil chamber 261b, causes the piston rod 262 to shorten towards the base end. This causes the left side frame 32L of the left rear leveling machine 31L to displace inward in the width direction of the leveling machine 3.

[0066] The left switching valve 33L has the function of selectively supplying working oil to the base-side oil chamber 261a and the rod-side oil chamber 261b of the left leveling machine telescopic cylinder 26L, which is the target of the supply, and the function of stopping the supply of working oil. One end of the left switching valve 33L is connected to the hydraulic pump 25 via the supply line 251 and to the tank 27 via the discharge line 271. The other end of the left switching valve 33L is connected to the first check valve 341 of the check valve 34 via the first line 336 and to the second check valve 342 of the check valve 34 via the second line 337.

[0067] Supply line 251, discharge line 271, first line 336, and second line 337 are connected together to the main body of the left switching valve 33L, thereby communicating with three switching path sections according to the position of the valve stem 331 moving in and out of the main body. The three switching path sections are a supply stop section 333 that stops supplying working oil to the left leveling machine telescopic cylinder 26L, a base end side supply section 334 that supplies working oil to the base end side oil chamber 261a of the left leveling machine telescopic cylinder 26L, and a rod side supply section 335 that supplies working oil to the rod side oil chamber 261b via the left control valve unit 35L.

[0068] The supply stop unit 333 has an internal path that cuts off the supply line 251 and connects the first line 336 and the second line 337 to the discharge line 271. If the valve stem 331 is positioned in the supply stop unit 333 by the drive of the solenoid coil 332, the left switching valve 33L can stop the supply of working oil from the hydraulic pump 25 and release excess pressure in the working oil via the first line 336 and the second line 337. This stops the supply of working oil to the left leveling machine telescopic cylinder 26L, maintaining the position of the piston rod 262.

[0069] The base-side supply section 334 has an internal path that connects the supply line 251 to the first line 336 in a fully open state, and connects the discharge line 271 to the second line 337. If the valve stem 331 is positioned in the base-side supply section 334 by the drive of the solenoid coil 332, the left switching valve 33L can supply working oil from the hydraulic pump 25 to the base-side oil chamber 261a. Furthermore, the left switching valve 33L can discharge working oil flowing through the rod-side oil chamber 261b via the left control valve unit 35L to the tank 27. As a result, the piston rod 262 of the left leveling machine telescopic cylinder 26L extends.

[0070] The rod-side supply section 335 has an internal path that connects supply line 251 to the second line 337 in a fully open state, and discharge line 271 to the first line 336. If the valve stem 331 is positioned in the rod-side supply section 335 by the drive of the solenoid coil 332, the left switching valve 33L can supply working oil from the hydraulic pump 25 to the rod-side oil chamber 261b via the left control valve unit 35L. Furthermore, the left switching valve 33L can discharge working oil from the base-side oil chamber 261a to the tank 27. As a result, the piston rod 262 of the left leveler telescopic cylinder 26L is shortened. The left switching valve 33L, based on the power supply from the leveler telescopic control device 54, continuously positions the valve stem 331 in either the base-side supply section 334 or the rod-side supply section 335, thereby limiting the flow direction of the working oil.

[0071] The check valve 34 has the function of preventing reverse flow in the direction of the working oil flow switched by the left switching valve 33L. The check valve 34 is a double check valve including a first check valve 341 connected to the first line 336 and a second check valve 342 connected to the second line 337. The first check valve 341 allows working oil supplied from the left switching valve 33L to the base-side oil chamber 261a to pass through. The second check valve 342 allows working oil supplied from the left switching valve 33L to the rod-side oil chamber 261b via the left control valve unit 35L to pass through. Furthermore, when the supply of working oil is stopped, the first check valve 341 and the second check valve 342 allow leakage of working oil from the left switching valve 33L to flow to the discharge line 271.

[0072] Furthermore, a branch line 391 is provided in the first line 336 between the first check valve 341 and the base-side oil chamber 261a. This branch line 391 branches the first line 336 and connects it to the discharge line 271. A safety valve 39 is provided in this branch line 391.

[0073] Safety valve 39 is configured to be closed under normal conditions, but to open the flow path of branch line 391 if a set pressure is reached. Safety valve 39 opens when the pressure of the working oil on the base end side oil chamber 261a is high, thereby allowing a portion of the working oil in the base end side oil chamber 261a to be directly discharged into tank 27, thus reducing the pressure.

[0074] The left control valve unit 35L linearly changes the flow rate of the working oil to control the extension and retraction speed of the left leveling machine telescopic cylinder 26L. The left control valve unit 35L is configured as an integrated structure that combines the proportional valve 36, the pressure compensation valve 37, and the drive switching valve 38. However, it is not limited to this; the pressure compensation valve 37 and the drive switching valve 38 can each be configured as separate devices.

[0075] The left control valve unit 35L is located on the second line 337 and controls the flow rate of the working oil supplied to and discharged from the rod-side oil chamber 261b. In the left leveling machine telescopic cylinder 26L, the amount of working oil supplied to the rod-side oil chamber 261b is small, thus reducing the pressure loss of the working oil. However, the left control valve unit 35L can also be located on the first line 336 to control the flow rate of the working oil supplied to and discharged from the base-side oil chamber 261a. Alternatively, the left control valve unit 35L can be located on both the first line 336 and the second line 337 to control the flow rate of the working oil separately.

[0076] The proportional valve 36 of the left control valve unit 35L moves the valve core 361 within the main body from the solenoid coil 362. The proportional valve 36 moves the valve core 361 between a closed state 363 (fully closing the flow path within the main body) and an open state 364 (fully opening the flow path within the main body). The valve core 361 can be a valve stem, a butterfly valve, or other valve cores. The valve core 361 causes the opening area of ​​the flow path to change linearly in proportion to the amount of current supplied to the solenoid coil 362. Therefore, the proportional valve 36 can discharge working oil at a flow rate corresponding to the position of the valve core 361.

[0077] The proportional valve 36 has two ports for working oil, one of which is connected to line 365 and the other to line 366. This proportional valve 36 is a bidirectional flow valve capable of selectively operating in two modes: working oil flows into one port and out of the other port; and working oil flows into the other port and out of one port. Lines 365 and 366 are connected to pressure compensation valve 37.

[0078] The aforementioned lines 365 and 366 are connected to one end of the pressure compensation valve 37. The other end of the pressure compensation valve 37 is connected to the second line 337 and the cylinder line 376, which connects to the rod-side oil chamber 261b of the left leveling machine telescopic cylinder 26L. The pressure compensation valve 37 has the function of maintaining a constant pressure difference between the pressure of the second line 337 and the pressure of the cylinder line 376. For example, even if the flow rate of the working oil flowing through the line changes, the pressure compensation valve 37 automatically adjusts the flow rate of the working oil to maintain a constant pressure difference at the minimum compensation pressure.

[0079] The pressure compensation valve 37 includes a valve stem 371 movably disposed within the main body and an electromagnetic coil 372 for advancing and retracting the valve stem 371. The valve stem 371 moves within a flow path switching section disposed within the main body, adjusting the opening area of ​​the flow path between the second line 337 and line 365, and adjusting the opening area of ​​the flow path between the cylinder line 376 and line 366. The flow path switching section has: a first opening configuration 373, where the opening areas of the second line 337 and the cylinder line 376 are the same; a second opening configuration 374, where the opening area on the second line 337 side is increased, and the opening area on the cylinder line 376 side is decreased; and a third opening configuration 375, where the opening area on the cylinder line 376 side is increased, and the opening area on the second line 337 side is decreased. However, the valve stem 371 can move linearly between the first opening configuration 373 and the third opening configuration 375 to adjust the opening area.

[0080] For example, when supplying working oil to the rod-side oil chamber 261b, the valve stem 371 moves between the first opening configuration 373 and the second opening configuration 374 to adjust the pressure difference of the working oil during supply to a constant. Conversely, when discharging working oil from the rod-side oil chamber 261b, the valve stem 371 moves between the first opening configuration 373 and the third opening configuration 375 to adjust the pressure difference of the working oil during discharge to a constant.

[0081] On the other hand, the drive switching valve 38 connects the branch line of the second line 337 with the branch line of the cylinder line 376, switching the connection state between the second line 337 and the cylinder line 376. The drive switching valve 38 drives the valve core 381 disposed in the main body through the electromagnetic coil 382, ​​thereby causing the valve core 381 to move between the open state 383 and the closed state 384.

[0082] In the open configuration 383, the second line 337 is connected to the cylinder line 376. Therefore, the connection from the left switching valve 33L to the rod-side oil chamber 261b is established. For example, when working oil is supplied from the left switching valve 33L to the rod-side oil chamber 261b, the working oil can flow without passing through the proportional valve 36 or the pressure compensation valve 37. Conversely, even when working oil is discharged from the rod-side oil chamber 261b to the left switching valve 33L, the working oil can still flow without passing through the proportional valve 36 or the pressure compensation valve 37.

[0083] On the other hand, in the closed configuration 384, the second line 337 and the cylinder line 376 are disconnected. Therefore, when working oil is supplied from the left switching valve 33L to the rod-side oil chamber 261b, the working oil can flow to the proportional valve 36 or the pressure compensation valve 37, and the flow rate of the working oil can be adjusted by the proportional valve 36 to allow it to flow into the rod-side oil chamber 261b. Conversely, when working oil is discharged from the rod-side oil chamber 261b to the left switching valve 33L, the working oil can also flow to the proportional valve 36 or the pressure compensation valve 37, and the flow rate of the working oil can be adjusted by the proportional valve 36 to discharge the working oil.

[0084] That is, the drive switching valve 38 can be described as a structure that switches between using and not using the proportional valve 36. Through this drive switching valve 38, the left control valve unit 35L can selectively switch between a first mode that adjusts the flow rate of the working oil in the proportional valve 36 and a second mode that allows the working oil to flow at a constant flow rate without passing through the proportional valve 36. In other words, the left control valve unit 35L can execute the first mode and the second mode, where the first mode adjusts the extension speed of the left leveler telescopic cylinder 26L through the proportional valve 36, and the second mode maintains the extension speed of the left leveler telescopic cylinder 26L at a limit value and remains constant through the left switching valve 33L.

[0085] The asphalt roller 100 involved in the embodiment is basically constructed in the manner described above. Next, refer to Figure 6 The control method for causing the telescopic cylinder 26 of the leveling machine to move is explained. Figure 6 This is a flowchart illustrating the control method of the telescopic cylinder 26 of the leveling machine.

[0086] In the control method of the leveling machine telescopic cylinder 26, the leveling machine control unit 50d of the controller 50 determines whether to adjust the telescopic speed of the leveling machine telescopic cylinder 26 (step S101). For example, adjusting the telescopic speed of the leveling machine telescopic cylinder 26 can be seen in the case of adjusting the width of the leveling machine 3 through automatic control. In automatic control, the leveling machine control unit 50d controls the left leveling machine telescopic cylinder 26L based on the left frame target track LTP, and controls the right leveling machine telescopic cylinder 26R based on the right frame target track RTP. At this time, the leveling machine control unit 50d identifies the current position of the left frame 32L based on the leveling machine position sensor 51C, and adjusts the telescopic speed of the left leveling machine telescopic cylinder 26L based on the deviation (offset) from the left frame target track LTP. The same applies to the right leveling machine telescopic cylinder 26R. Therefore, if the leveling machine control unit 50d determines that the extension speed of the leveling machine telescopic cylinder 26 is adjusted according to the opening of the automatic control switch of the operating device (step S101: "Yes"), then proceed to step S102.

[0087] Next, the leveling machine control unit 50d confirms the target movement direction of the leveling machine telescopic cylinder 26 (step S102). The target movement direction is the direction in which the leveling machine telescopic cylinder 26 extends and retracts. For example, if it is the left leveling machine telescopic cylinder 26L, it extends when moving to the left and retracts when moving to the right. On the other hand, if it is the right leveling machine telescopic cylinder 26R, it extends when moving to the right and retracts when moving to the left.

[0088] Furthermore, the leveling machine control unit 50d calculates the extension and retraction speed of the leveling machine telescopic cylinder 26 (step S103). The extension and retraction speed of the leveling machine telescopic cylinder 26 is calculated based on the deviation, so that the closer the current position of the side frame 32 is to the target position (side frame target track), the slower the speed. As a result, the asphalt roller 100 can position the moving side frame 32 at the target position with high precision.

[0089] Furthermore, the leveling machine control unit 50d calculates the electrical value input to the electromagnetic proportional flow valve (proportional valve 36) based on the calculated extension and retraction speed of the leveling machine telescopic cylinder 26 (step S104). For example, the leveling machine control unit 50d may have pre-stored chart information or functions showing the correspondence between the extension and retraction speed of the leveling machine telescopic cylinder 26 and the electrical value, and extract the electrical value corresponding to the extension and retraction speed by referring to the chart information.

[0090] The leveling machine control unit 50d sends a control command containing an electrical value to the leveling machine telescopic control device 54, supplying power according to the electrical value indicated by the leveling machine telescopic control device 54 to the electromagnetic proportional flow valve (proportional valve 36) (step S105). Furthermore, in this stage, the leveling machine control unit 50d actuates the switching valve 33 according to the target direction of movement, selecting either the extension or retraction of the leveling machine telescopic cylinder 26, and actuates the drive switching valve 38 to disconnect the second line 337 from the cylinder line 376. This allows the working oil to flow through the proportional valve 36.

[0091] In the control valve unit 35, the electromagnetic proportional flow valve (proportional valve 36) changes its opening area according to the supplied power (step S106). Therefore, for example, when working oil is supplied from the hydraulic pump 25 to the rod-side oil chamber 261b, the working oil flows through the switching valve 33, the second check valve 342, the pressure compensation valve 37, and the proportional valve 36, and the flow rate is adjusted in the proportional valve 36.

[0092] The leveling machine telescopic cylinder 26 extends and retracts at a set speed by adjusting the flow rate of the working oil flowing in or out (step S107). As a result, the leveling machine telescopic cylinder 26 can move the supported side frame 32 along the target direction of movement.

[0093] When the leveling machine control unit 50d operates the leveling machine telescopic cylinder 26, it determines whether the side frame 32 has reached the target position (step S108). This determination can be made by monitoring the detection information of the leveling machine position sensor 51C, or by monitoring the movement time of the leveling machine telescopic cylinder 26 and determining based on the time it takes to reach the target position. If the side frame 32 has not reached the target position (step S108: "No"), the process returns to step S102 and repeats the same procedure. Therefore, if the side frame 32 has not reached the target position, the target movement direction and telescopic speed are recalculated, and a new current value is output; the closer the side frame 32 is to the target position, the smaller the current value is output. Conversely, if the side frame 32 has reached the target position (step S108: "Yes"), the process ends.

[0094] Furthermore, in step S101, without automatic control of the width of the leveling machine 3 (step S101: "No"), the operator manually controls the movement of the leveling machine telescopic cylinder 26. At this time, proceed to step S109.

[0095] In step S109, the switching valve 33 controls the flow of working oil in the leveling machine telescopic cylinder 26 according to the opening and closing operation of the leveling machine telescopic switch, which is an operating device. As a result, the leveling machine telescopic cylinder 26 extends and retracts at a constant speed (the limit of the telescopic speed), and the width of the leveling machine 3 can be adjusted in advance according to the operator's operating feel.

[0096] As described above, in the control method of the leveling machine telescopic cylinder 26, the target movement direction (supply object) is switched by the switching valve 33, and the flow rate of the working oil is adjusted by the proportional valve 36, thereby adjusting the telescopic speed of the leveling machine telescopic cylinder 26 to an appropriate speed. Furthermore, when it is desired to set the telescopic speed of the leveling machine telescopic cylinder 26 to a constant (limit value) and move it, the working oil is prevented from flowing to the proportional valve 36 by driving the switching valve 38, thereby allowing the working oil to be supplied directly to the leveling machine telescopic cylinder 26 from the switching valve 33.

[0097] Furthermore, when switching from extension to retraction or vice versa in the leveling machine's telescopic cylinder 26, the switching valve 33 allows for smooth switching by moving the valve stem 331 between the base-side supply section 334 and the rod-side supply section 335. At this time, the smooth switching of the working oil flow allows the working oil to stabilize earlier. Therefore, even when adjusting the working oil flow rate via the proportional valve 36, the target direction of the working oil movement can be controlled by stopping the flow of working oil to the proportional valve 36 and switching the working oil direction via the switching valve 33 at the timing of switching the extension and retraction of the leveling machine's telescopic cylinder 26.

[0098] Furthermore, the asphalt tumbler 100 according to the present invention is not limited to the above-described embodiments, and various modifications can be adopted. For example, the hydraulic circuit of the tumbler telescopic cylinder 26 can be appropriately switched and stopped by using other on / off valves, so it may be a structure without a pressure compensation valve 37 or a drive switching valve 38. Also, for example, the proportional valve 36 is not limited to an electromagnetic proportional flow valve, and proportional valves 36 with other drive methods can also be used.

[0099] <Postscript> The technical concept and effects of the present invention described in the above embodiments are described below.

[0100] The first aspect of the present invention is an asphalt roller 100, which includes a leveling machine 3 that moves in the paving direction while spreading the paving material PV evenly. The asphalt roller 100 includes: a leveling machine telescopic cylinder 26 that extends and retracts with the supply of working oil, causing a side frame 32, which is the spreading limit of the leveling machine 3, to move; and a hydraulic pump 25 that supplies working oil to the leveling machine telescopic cylinder 26. A switching valve 33 and a proportional valve 36 are provided on the path between the hydraulic pump 25 and the leveling machine telescopic cylinder 26. The switching valve 33 switches the target of the working oil supply, and the proportional valve 36 adjusts the flow rate of the working oil.

[0101] As described above, the asphalt tumbler 100 has a switching valve 33 and a proportional valve 36 between the hydraulic pump 25 and the leveling machine telescopic cylinder 26. The flow of working oil can be controlled by the functions of these two valves. For example, when switching the extension and retraction of the leveling machine telescopic cylinder 26, the asphalt tumbler 100 switches the working oil flow using the switching valve 33, thereby stabilizing the working oil flow. Furthermore, when adjusting the extension and retraction speed of the leveling machine telescopic cylinder 26, the asphalt tumbler 100 adjusts the working oil flow using the proportional valve 36, thereby allowing the width of the leveling machine to extend and retract at an appropriate speed.

[0102] Furthermore, the proportional valve 36 can adjust the flow rate of the working oil supplied to the telescopic cylinder 26 of the leveling machine, and can also adjust the flow rate of the working oil discharged from the telescopic cylinder 26 of the leveling machine. Thus, the asphalt roller 100 can easily adjust the extension and retraction speeds of the telescopic cylinder 26 of the leveling machine during extension and retraction by means of a single proportional valve 36.

[0103] Furthermore, as the side frame 32 approaches the target position, the proportional valve 36 reduces the flow of working oil, thereby slowing down the extension and retraction speed of the leveling machine telescopic cylinder 26. Thus, the asphalt tumbler 100 can slow down the extension and retraction speed of the leveling machine telescopic cylinder 26 near the target position, enabling the side frame 32 to move to the target position with high precision.

[0104] Furthermore, the switching valve 33 allows the working oil to circulate at the upper limit of the flow rate of the working oil supplied to or discharged from the leveling machine telescopic cylinder 26. Thus, a sufficient flow rate of working oil can be allowed to pass through the switching valve 33, thereby improving, for example, the efficiency of the telescopic switching of the leveling machine telescopic cylinder 26.

[0105] Furthermore, the system includes a drive switching valve 38 capable of switching between a first mode and a second mode. In the first mode, working oil flows from the switching valve 33 or the leveler telescopic cylinder 26 to the proportional valve 36. In the second mode, working oil flows between the switching valve 33 and the leveler telescopic cylinder 26 without passing through the proportional valve 36. Thus, the asphalt tumbler 100 can easily switch between the first and second modes via the drive switching valve 38.

[0106] Furthermore, the system includes a controller 50 that controls the switching valve 33, the proportional valve 36, and the drive switching valve 38. The controller 50 determines whether to adjust the extension speed of the leveling machine's telescopic cylinder 26. If the extension speed of the leveling machine's telescopic cylinder 26 is adjusted, the system is set to a first state; if the extension speed of the leveling machine's telescopic cylinder 26 is not adjusted, the system is set to a second state. Thus, the asphalt roller 100 can appropriately control the extension speed of the leveling machine's telescopic cylinder 26.

[0107] Furthermore, it includes a pressure compensation valve 37, which maintains a constant pressure difference between the working oil pressure flowing into the proportional valve 36 and the working oil pressure flowing out of the proportional valve 36. Thus, the asphalt roller 100 can maintain a constant pressure difference when the working oil flows to the proportional valve 36, ensuring stable flow of the working oil.

[0108] Furthermore, the leveling machine telescopic cylinder 26 has a base-side oil chamber 261a and a rod-side oil chamber 261b, which are the targets for supplying working oil. A proportional valve 36 is disposed in the path between the switching valve 33 and the rod-side oil chamber 261b. Thus, the proportional valve 36 can adjust the flow rate of working oil in the rod-side oil chamber 261b, where the supply of working oil is less, thereby reducing the pressure loss of the working oil.

[0109] The asphalt roller 100 disclosed herein is illustrative in all respects and not restrictive. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the technical solution. The items described in the above embodiments can be adopted with other structures and combined without contradiction.

Claims

1. An asphalt roller, comprising a leveling machine that moves in the paving direction while spreading paving material evenly, said asphalt roller comprising: The leveling machine's telescopic cylinder extends and retracts with the supply of working oil, causing the side frame, which serves as the leveling machine's spreading limit, to move; and The hydraulic pump supplies the working oil to the telescopic cylinder of the leveling machine. A switching valve and a proportional valve are installed on the path between the hydraulic pump and the telescopic cylinder of the leveling machine. The switching valve switches the supply target of the working oil, and the proportional valve adjusts the flow rate of the working oil.

2. The asphalt roller according to claim 1, wherein, The proportional valve can adjust the flow rate of the working oil supplied to the telescopic cylinder of the leveling machine, and can also adjust the flow rate of the working oil discharged from the telescopic cylinder of the leveling machine.

3. The asphalt roller according to claim 2, wherein, The proportional valve reduces the flow of working oil as the side frame approaches the target position, thereby slowing down the extension and retraction speed of the leveling machine's telescopic cylinder.

4. The asphalt roller according to any one of claims 1 to 3, wherein, The switching valve allows the working oil to circulate at an upper limit of the flow rate of the working oil supplied to or discharged from the telescopic cylinder of the leveling machine.

5. The asphalt roller according to claim 4, comprising: The drive switching valve can switch between a first mode and a second mode. The first mode allows the working oil to flow from the switching valve or the leveling machine telescopic cylinder to the proportional valve. The second mode allows the working oil to flow between the switching valve and the leveling machine telescopic cylinder without passing through the proportional valve.

6. The asphalt tumbling machine according to claim 5, comprising: The controller controls the switching valve, the proportional valve, and the drive switching valve. The controller determines whether to adjust the extension speed of the leveling machine's telescopic cylinder. If the extension speed of the leveling machine's telescopic cylinder is adjusted, it is set to the first state; if the extension speed of the leveling machine's telescopic cylinder is not adjusted, it is set to the second state.

7. The asphalt tumbling machine according to any one of claims 1 to 3, comprising: The pressure compensation valve maintains a constant pressure difference between the pressure of the working oil flowing into the proportional valve and the pressure of the working oil flowing out of the proportional valve.

8. The asphalt tumbling machine according to any one of claims 1 to 3, wherein, The leveling machine telescopic cylinder has a base-end side oil chamber and a rod-side oil chamber, which are the objects to which the working oil is supplied. The proportional valve is located in the path between the switching valve and the rod-side oil chamber.

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