WO2016093382A1

WO2016093382A1 - Paver with traction control function

Info

Publication number: WO2016093382A1
Application number: PCT/KR2014/012055
Authority: WO
Inventors: Nishanth KUMAR
Original assignee: Volvo Construction Equipment Ab
Priority date: 2014-12-09
Filing date: 2014-12-09
Publication date: 2016-06-16

Abstract

The present disclosure relates to a paver with traction control function, characterized by increasing traction force applied to left and right driving wheels to minimize occurrence of a dive wheel slip by partially lifting a screed unit simultaneously disconnecting a traction control line internally connecting left and right wheel drive hydraulic motors as soon as a drive wheel slip is detected in any one of the left and right driving wheels upon comparison of sensor signals of left and right wheel sensors installed in left and right wheel drive hydraulic motors for operating the left and right driving wheels. As a result, the quality and work efficiency of road pavement can be improved.

Description

PAVER WITH TRACTION CONTROL FUNCTION

The present disclosure relates to a road construction machine, and more specifically, to a paver for widely laying a paving material, such as wet mix macadam (WMM), on the road.

The paver is a construction machine for widely laying a paving material, such as, WMM, on the road in predetermined thickness and width.

Such a paver typically comprises: a tractor unit, the front of which is loaded with a paving material; a screed unit for evenly laying the paving material discharged from the tractor unit; and left and right tow arms for connecting the screed unit to be liftable via left and right screed lifting cylinders simultaneously with connecting the screed unit to the rear of the tractor unit to be towable.

Herein, the tractor unit comprises a vehicle body equipped with an engine, which generates a driving force, a driving means for driving and moving, and a cab forming a space in which an operator sits.

The driving means may be formed of wheels or a crawler. Depending on the driving means, the paver is classified into a wheeled paver and a crawler type paver.

The wheeled paver comprises rear wheels, which are rotatably installed in both rear sides as a driving wheel, and further comprises a first front wheel, which is rotatably installed in both front sides to increase running stability and traction force, and a second front wheel, which is rotatably installed in the rear adjacent to the first wheel.

When normally driving, both rear wheels can be rotatably operated at an equal speed. When turning, both rear wheels are equipped with hydraulic motors, which are rotatably operated by a hydraulic pump, respectively, to be differently operated, wherein the hydraulic motors in both sides are interconnected under the interposition of the hydraulic line in which a traction control valve is installed.

Generally, the traction force between the left rear wheel and the road is not equal to the traction force between the right rear wheel and the road by road condition or driving environment. In such case, the driving force is distributed to left and right driving wheels such that a surplus of the driving force applied to one rear wheel, to which relatively low traction force is applied, is transferred to the other rear wheel, to which relatively low traction force by the aforesaid internal connection, thereby assuring running stability of the wheeled paver.

However, under certain condition that the traction force between the rear wheel and the road surface is excessively lowered, for example, such condition as laying a paving material on the road, as the driving force of the hydraulic motor is excessively greater than the traction force between the rear wheel and the road, a drive wheel slip, i.e., the rear wheel, which is a driving wheel, spins with no traction, occurs.

Specifically, when laying a paving material on the road, if a drive wheel slip occurs in any one of both rear wheels of the wheeled paver and lasts for some period of time, the running stability of the wheeled paver is lowered, thereby causing problems, lowered quality of road pavement and lowered working speed.

The present disclosure has been made to solve the above-mentioned problems, and relates to a paver with traction control function to minimize occurrence of a drive wheel slip by increasing the traction force applied to the left and right driving wheels by partially lifting the screed unit simultaneously with separating the traction control line internally connecting the left and right wheel drive hydraulic motors as soon as a slip in any one of the left and right driving wheels is detected upon comparison of sensor signals of the left and right wheel sensors installed in the left and right wheel drive hydraulic motor for driving left and right driving wheels.

The present disclosure provides a paver with traction control function, comprising: a tractor unit, wherein an engine is loaded; left and right driving wheels are installed; a cab which an operator boards is provided; and left and right wheel drive hydraulic pump and a cylinder drive hydraulic pump are installed; a screed unit installed in the rear of the tractor unit; left and right tow arms for connecting the screed unit to the tractor unit; left and right screed lifting cylinders, which connect the left and right tow arms to the left and right sides of the tractor unit liftably, and are connected to each other via a cylinder connection line; left and right wheel drive hydraulic motors, which are connected respectively to the left and right wheel drive hydraulic pumps to rotatably operate the left and right driving wheels and are connected to each other via a traction control line; a traction control valve installed in the traction control line to connect or separate the traction control line; a screed control valve, which is installed in the screed control line connecting the cylinder drive hydraulic pump to the cylinder connection line to connect or separate the screed control line; left and right wheel sensors, which are installed in each of the left and right driving motors and detect the number of rotation of the left and right driving wheels; and a controller, which is installed in the tractor unit and detects a drive wheel slip by a difference in the number of rotation between the left and right driving wheels upon comparison of sensor signals of the left and right wheel sensors, wherein the controller opens the screed control valve to lift the screed unit simultaneously with closing the traction control valve to separate the traction control line when a drive wheel slip is detected.

In accordance with a preferred embodiment of the present disclosure, the paver further comprises a mode setting switch, which is installed in the cab of the tractor unit and sets a driving mode and a road paving mode, respectively.

In accordance with a preferred embodiment of the present disclosure, the controller opens the screed control valve simultaneously with closing the traction control valve only when the road pavement mode is set by the mode setting switch. When the driving mode is set by the mode setting switch, the traction control valve is maintained to be in the opened state and the screed control valve is maintained to be in the closed state.

In accordance with a preferred embodiment of the present disclosure, the left and right driving wheels are left and right rear wheels.

In accordance with a preferred embodiment of the present disclosure, the left and right wheel sensors are formed of hall-effect sensors for measuring the number of rotation of the left and right wheel sensors.

In accordance with a preferred embodiment of the present disclosure, the controller is integrated into the engine control unit (ECU) of the tractor unit.

The present disclosure is advantageous in that occurrence of a dive wheel slip is minimized by partially lifting a screed unit simultaneously disconnecting a traction control line internally connecting left and right wheel drive hydraulic motors as soon as a drive wheel slip is detected in any one of the left and right driving wheels upon comparison of sensor signals of left and right wheel sensors installed in left and right wheel drive hydraulic motors for operating the left and right driving wheels.

FIG. 1 is a side view of a paver with traction control function in accordance with an embodiment of the present disclosure;

FIG. 2 is a block diagram illustrating the operation relation of a paver with traction control function in accordance with an embodiment of the present disclosure.

Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. While the present disclosure will be described in conjunction with the following embodiments, it will be understood that they are not intended to limit the present disclosure to these embodiments alone. On the contrary, the present disclosure is intended to cover alternatives, modifications, and equivalents which may be included within the spirit and scope of the present disclosure as defined by the appended claims. Furthermore, in the following detailed description of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, embodiments of the present disclosure may be practiced without these specific details.

FIG. 1 shows a side view of a paver with traction control function in accordance with an embodiment of the present disclosure. FIG. 2 shows a block diagram illustrating the operation relation of the paver with traction control function in accordance with an embodiment of the present disclosure.

As shown in FIG. 1 and FIG. 2, the paver with traction control function in accordance with an embodiment of the present disclosure basically comprises a tractor unit TR, a screed unit SC1, left and right tow arms TA1, TA2 for connecting the tractor unit TR to the screed unit SC1 and left and right screed lifting cylinders C1, C2 connecting the left and right tow arms TA1, TA2 liftably to the left and right sides of the tractor unit TR.

The tractor unit TR is an element, which transports a paving material loaded to the front while driving on the road and discharges the paving material and tows the screed unit SC1 simultaneously.

An engine E, which generates driving force, is loaded in the tractor unit TR. Left and right driving wheels R1, R2 rotatably operated by the engine E are installed in the left and right sides of the tractor unit TR, and a cab which an operator boards is installed in the top of the tractor unit.

The left and right driving wheels R1, R2 are preferably left and right rear wheels. Further, it is more preferable that first rear wheels F1, F2 are installed to be rotatable in both front sides of the tractor unit TR and second rear wheels F3, F4 are installed to be rotatable in both rear sides adjacent to the first front wheels F1, F2, respectively, for purposes of running stability of the tractor unit TR of the paver and increased traction force.

Further, the tractor unit TR comprises a receiving hopper (not shown), to which a paving material, such as, for example, wet mix macadam (WMM), a conveyor (not shown) for transporting the paving material, and a spreading auger (not shown) for evenly discharging the transported paving material to the road surface. The paving material loaded to the receiving hopper is transported to the rear side of the tractor unit TR via the conveyor and is provided to the spreading auger, which evenly discharges the paving material to the road surface through rotation itself.

Further, left and right wheel drive hydraulic pumps P1, P2 for generating driving force provided to the left and right driving wheels R1, R2 and a cylinder drive hydraulic pump P3 for providing the oil pressure to the left and right screed lifting cylinders C1, C2 in a direction of lifting the screed unit SC1 are installed to the tractor unit TR, specifically, the engine E.

The screed unit SC1 is towed by the tractor unit TR and allows the paving material discharged from the tractor unit TR to the road surface to be widely dispersed.

The screed unit SC1 comprises left and right screed plates (not shown), wherein lower ends of the corresponding surfaces facing each other are hinge-coupled, and a crowning apparatus (not shown), wherein one end is hinge-coupled to the left screed plate and the other end is hinge-coupled to the right screed plate and a crown angle is adjusted by extending or reducing the length thereof.

Left and right tow arms TA1, TA2 are units for towably connecting the screed unit SC1 to the tractor unit TR.

One end of the left tow arm TA1 is pivot-connected to the left side of the tractor unit TR, and the other end of the left tow arm TA1 is connected to the left side of the screed unit SC1. Further, one end of the right tow arm TA2 is pivot-connected to the right side of the tractor unit TR, and the other end of the right tow arm TA2 is connected to the right side of the screed unit SC1.

Left and right screed lifting cylinders C1, C2 connect the left and right tow arms TA1, TA2 liftably to both sides of the tractor unit TR and correspond to levelling cylinders. The left and right screed lifting cylinders C1, C2 are connected to each other via a cylinder connection line L1. The cylinder connection line L1 is connected to the center of a screed control line L3, the oil pressure of the cylinder drive hydraulic pump P3 is provided to the left and right screed lifting cylinders C1, C2, whereby partially lifting the screed unit SC1.

Left and right tow arms TA1, TA2 are connected to both sides of the tractor unit TR by leveling cylinders (not shown) in addition to the left and right screed lifting cylinders C1, C2. The left and right tow arms TA1, TA2 are adjustable in various operation modes by controlling the lengths of the left and right screed lifting cylinders C1, C2 and the leveling cylinders . The leveling cylinders are used to change the mat thickness and to control variation in mat thickness while paving. The screed lifting cylinders C1, C2 are also sued for other functions like lifting the screed off the ground while transportation and travelling.

Left and right wheel drive hydraulic motors M1, M2 for rotating and operating the left and right driving wheels are connected to the above-mentioned left and right wheel drive hydraulic pumps P1, P2, respectively. The left and right wheel drive hydraulic motors M1, M2 are formed of normal hydraulic motors, which convert the oil pressure of the hydraulic fluid into rotation force.

When normally driving, the left and right driving wheels R1, R2 can be rotatably operated at an equal speed. When turning, in order for the left and right driving wheels R1, R2 to be differently operated, the left and right wheel drive hydraulic pumps P1, P2 are connected to each other by the traction control line L2, on which a traction control valve T1 for opening or closing the traction control line L2 is installed. The traction control valve T1 is formed of a normal fluid control valve by which a connection channel or a disconnection channel is selectively set while a spool moves according to a control signal of the controller ECU.

Further, the cylinder drive hydraulic pump P3 and the cylinder connection line L1 are connected by the screed control line L3, on which a screed control valve S1 is installed. Based on whether the screed control valve S1 is opened or closed, the screed control valve S1 connects the screed control line L3 to the cylinder drive hydraulic pump P3 such that the oil pressure discharged from the cylinder drive hydraulic pump P3 is provided to the left and right screed lifting cylinders C1, C2 to lift the screed unit SC1 or disconnects the screed control line L3 from the cylinder drive hydraulic pump P3 such that the oil pressure discharged from the cylinder drive hydraulic pump P3 is not provided to the left and right screed lifting cylinders C1, C2. The screed control valve S1 is formed of a normal fluid control valve by which a connection channel or a disconnection channel is selectively set while a spool moves according to a control signal of the controller ECU.

Left and right wheel sensors H1, H2 are correspondingly installed in the above-mentioned left and right driving wheels R1, R2, respectively. The left and right wheel sensors H1, H2 detect the number of rotation of the left and right driving wheels R1, R2 through the number of rotation of the left and right wheel drive hydraulic motors M1, M2, and may be formed of various sensors for measuring the number of rotation, and are preferably formed of the known hall-effect sensors.

The controller ECU is installed in the above-mentioned tractor unit TR. The controller ECU detects a drive wheel slip by a difference in the number of rotation between the left and right driving wheels R1, R2 upon comparison of sensor signals of the left and right wheel sensors H1, H2, and are electrically connected to the left and right wheel sensors H1, H2, respectively.

Further, the controller ECU determines that a drive wheel slip occurs when the difference in the number of rotation between the left and right driving wheels R1, R2 is in excess of the predetermined value.

Immediately after a slip is detected in any one of the driving wheels by the controller ECU, the controller ECU closes the traction control valve T1 to be the traction control line L2 disconnected. As a result, the left and right driving wheels R1, R2 are independently operated without mutually complementing the driving force. In this case, the controller ECU independently controls the rotational operation of the left and right driving wheels R1, R2 so that a drive wheel slip may occur no longer by minimizing the driving force applied to the other driving wheel in which no drive wheel slip occurred.

Further, when a drive wheel slip is detected in any one of the driving wheels by the controller ECU, the controller ECU connects the screed control line L3 to the cylinder drive hydraulic pump P3 by opening the screed control valve S1 to provide the oil pressure discharged from the cylinder drive hydraulic pump P3 to the left and right screed lifting cylinders C1, C2, thereby the screed unit SC1 is partially lifted. Herein, it is preferable that the screed unit SC1 is partially lifted in a moment within the scope of not causing any problems in the quality of the pavement of a road.

If the screed unit SC1 is partially lifted, the load applied to the left and right driving wheels R1, R2 is increased, and therefore, the traction force between the left and right driving wheels R1, R2 and the road surface is increased, which results in resolving the problem of drive wheel slip.

Such controller ECU may be formed separately from the engine control unit of the tractor unit TR, but is preferably formed to be integrated into the engine control unit of the tractor unit TR.

The traction control function of the paver in accordance with an embodiment of the above-mentioned present disclosure is preferably operated only with respect to the road pavement mode and not the driving mode for movement.

To this end, the cab of the above-mentioned tractor unit TR, specifically, the operational panel, may be equipped with a mode setting switch SW1 for setting two operation modes of the paver with traction control function in accordance with an embodiment of the present disclosure, i.e., a driving mode and a road pavement mode, respectively.

Herein, the controller ECU allows the traction control function to be activated to close the traction control valve T1 simultaneously with opening the screed control valve S1 only when a road pavement mode is set by the mode setting switch SW1. Further, when a driving mode is set by the mode setting switch SW1, the controller ECU allows the traction control function to be inactivated to maintain the traction control valve T1 to be in the opened state and the screed control valve S1 to be in the closed state.

The paver with traction control function in accordance with the above-mentioned present disclosure separates the traction control line L2 internally connecting the left and right wheel drive hydraulic motors M1, M2 such that the left and right driving wheels R1, R2 are individually operated without mutually complementing the driving force simultaneously partially lifting the screed unit SC1 to increase the traction force applied to the left and right driving wheels R1, R2 and minimize occurrence of a drive wheel slip as soon as the paver detects a drive wheel slip in any one of the left and right driving wheels R1, R2 upon comparison of sensor signals of the left and right wheel sensors H1, H2 installed in the left and right wheel drive hydraulic motors M1, M2, which operate the left and right driving wheels R1, R2. As a result, the quality and work efficiency of the pavement of a road can improved.

Although the invention has been described with reference to the preferred embodiments in the attached figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.

The present disclosure is applicable to a road construction machine, and more specifically, to a paver

Claims

A paver with traction control function, comprising:

a tractor unit, wherein an engine is loaded; left and right driving wheels are installed; , a cab which an operator boards is provided; and left and right wheel drive hydraulic pumps and a cylinder drive hydraulic pump are installed;

a screed unit, which is installed in the rear of the tractor unit;

left and right tow arms for connecting the screed unit to the tractor unit;

left and right screed lifting cylinders, which connect the left and right tow arms to the left and right sides of the tractor unit liftably, and which are connected to each other by a cylinder connection line;

left and right wheel drive hydraulic motors, which are connected respectively to the left and right wheel drive hydraulic pumps to rotatably operate the left and right driving wheels, and which are connected to each other by a traction control line;

a traction control valve, which is installed on the traction control line to connect or disconnect the traction control line;

a screed control valve, which is installed on the screed control line connecting the cylinder drive hydraulic pump to the cylinder connection line to connect or disconnect the screed control line;

left and right wheel sensors, which are installed respectively in the left and right drive motors and detect the number of rotation of the left and right driving wheels; and

a controller, which is installed in the tractor unit and detects a drive wheel slip based on a difference in the number of rotation between the left and right driving wheels upon comparison of sensor signals of the left and right wheel sensors, wherein the controller opens the screed control valve to lift the screed unit simultaneously with closing the traction control valve to disconnect the traction control line when detecting the drive wheel slip.
The paver with traction control function according to claim 1, further comprising a mode setting switch, which is installed in the cab of the tractor unit and sets a driving mode and a road pavement mode, respectively.
The paver with traction control function according to claim 2, wherein the controller opens the screed control valve simultaneously with closing the traction control valve only when a road pavement mode is set by the mode setting switch; the controller maintains the traction control valve to be in the opened state and the screed control valve to be in the closed state when a driving mode is set by the mode setting switch.
The paver with traction control function according to any one of claims 1 to 3, wherein the driving wheels are rear wheels.
The paver with traction control function according to any one of claims 1 to 3, wherein the left and right wheel sensors are formed of hall-effect sensors for measuring the number of rotation.
The paver with traction control function according to any one of claims 1 to 3, wherein the controller is integrated into an engine control unit (ECU) of the tractor unit.