JPH04330106A - Paving thickness controlling method for grader - Google Patents

Abstract

PURPOSE:To construct a continuous pavement as flat as practicable and without interruption by making paving work so that the thickness lies within a reference range as specified. CONSTITUTION:A vehicle 1 is equipped with a pair of height sensors 13, 14, an inclination sensor 15, and a calculating device 30. A guide sensor 19 is mounted on a screed 5 supported by a leveling arm 6, which rotates up and down round a supporting shaft 7 as fulcrum. This guide sensor 19 moves along the reference line 25 consisting of curb stones etc., and a pivot cylinder 8 moving the supporting shaft 7 up and down is controlled so that the asphalt mix material is laid and graded while the screed 5 is kept with a certain level difference to the reference line 25. The guide sensor 19 is moved up and down by a vertical motion device 10 relative to the screed 5. The calculating device 30 calculates the paving thickness on the basis of the results from measuring made by the height sensors 13, 14 and inclination sensor 15, also calculates the difference of the mean paved thickness from the target thickness, operates the vertical motion device 10 on the basis of the difference obtained, and moves the guide sensor 19 up and down.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pavement thickness control method applied to leveling machines such as asphalt finishers.

0002

[Prior Art] Conventionally, methods for controlling pavement thickness include methods for controlling pavement thickness based on curbs and gutters on the side of the road to be paved, or wires stretched between two points, and other methods. A method is known in which the pavement thickness is measured by a means and the pavement thickness is controlled based on the measurement result.

0003

[Problems to be Solved by the Invention] The former method emphasizes the flatness of the pavement. For example, if a wire is stretched in a straight line between two points and used as a standard for paving, Even if there are large irregularities in the roadbed, it will be paved regardless of the unevenness, and although the pavement will be finished flat, there is a dissatisfaction that the thickness will vary greatly depending on the unevenness of the roadbed.

[0004] Also, the latter method, contrary to the former method,
Although the thickness of the pavement is uniform, there is a problem that if the roadbed is uneven, it will not be flat.

The present invention provides a pavement leveling machine capable of continuously and automatically controlling the pavement thickness so that the pavement thickness is within a predetermined reference range and the pavement is as flat as possible. The purpose is to provide a thickness control method.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a screed at the rear of a vehicle whose inclination angle in the longitudinal direction can be changed by an angle adjustment means, and a screed at the front of the screed of the vehicle. A pair of height and inclination sensors that individually measure the distance to the paved roadbed are installed at a required interval in the front-rear direction. In a leveling machine that is electrically connected to a calculation device that calculates the paving thickness of asphalt mixture using a screed based on the results,
A guide sensor that moves along a reference line placed next to the pavement roadbed and controls the angle adjustment means is provided on the screed so that it can be moved up and down with a vertical device, and the pavement thickness calculated by the calculation device is set to a predetermined value. If the pavement thickness deviates from the specified value, the arithmetic unit operates the up-and-down device to move the guide sensor upward or downward relative to the screed, thereby controlling the pavement thickness so that it falls within the reference range.

[0007]

[Operation] During paving, the pair of height sensors individually measure the distance to the paved roadbed, and the calculation device calculates the pavement thickness based on the measurement results of the height and inclination sensors. The guide sensor also moves along the reference line and controls the screed angle adjustment means.

[0008] In the above operation, for example, when the pavement thickness becomes larger than a predetermined upper limit value, the arithmetic unit activates the up-and-down device to raise the guide sensor relative to the screed, and when the pavement thickness becomes larger than a predetermined upper limit, When the value is smaller than a predetermined lower limit value, the raising and lowering device is operated to lower the guide sensor relative to the screed. As a result, the pavement thickness falls within a predetermined range, and the flatness of the pavement is ensured to the minimum level. The vertical movement of the guide sensor relative to the screed is automatically performed by a calculation device, so
Unlike when workers manually move the guide sensor up and down, paving can be done continuously without interruption.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The attached drawings show an example of an asphalt finisher embodying the present invention, and reference numeral 1 in the drawings indicates a vehicle running the asphalt finisher AF. A hopper 2 into which asphalt mixture is placed is provided in the front part. The asphalt mixture in the hopper 2 is transferred rearward (to the right in FIG. 1) by a feeder at the bottom of the vehicle body, then spread evenly left and right by a screw, and evenly spread by a pair of left and right screeds 5.

The screed 5 is supported via a leveling arm 6 by a support shaft 7 provided on a substantially central side surface of the vehicle 1. The support shaft 7 is operated to move up and down by a pivot cylinder (angle adjustment means) 8. Note that the basic structure of the asphalt finisher AF is well known.

Further, reference numeral 11 denotes measuring devices provided on the left and right sides, respectively. The measuring device 11 includes a first height sensor 13 provided at the tip of the measuring arm 12, and a second height sensor provided at the center of the measuring arm 12 and paired with the first height sensor 13. 14, and a tilt sensor 15 that measures the tilt angle of the measurement arm 12. The base end (right end in FIG. 1) of the measuring arm 12 is supported by a frame 5a that supports the screed 5, so that the measuring arm 12 tilts together with the screed 5.

Various types of first and second height sensors 13 and 14 are conceivable, but sensors using ultrasonic waves are used here. Furthermore, as shown in FIG. 4, the distance M between the two sensors 13 and 14 is greater than
The height H0 of both sensors 13 and 14 relative to the screed 5 is always a constant value. (See Figure 5). Reference numeral 17 denotes a distance sensor for calculating the travel distance, which is provided at the lower front end of the traveling vehicle 1.

An arm 18 is integrally fixed to the frame 5a of the screed 5, and an outer cylinder 20 is fixed to the tip of the arm 18 (see FIG. 3). An actuator 21 such as an electric motor or a hydraulic motor is provided at the top of the outer cylinder 20.
Further, an inner cylinder 22 is inserted into the outer cylinder 20 so as to be freely vertically movable while being prevented from freely rotating in the circumferential direction. A threaded rod 23 is coupled to the output shaft of the actuator 21 and screwed into the inner cylinder 22 . A guide sensor 19 is attached to the lower end of the inner cylinder 22. The guide sensor 19 is the actuator 2
1 moves the threaded rod 23 up and down with the inner cylinder 22 relative to the screed 5. A guide sensor 19 is provided in the outer cylinder 20.
A movement sensor 24 is attached to detect the amount of vertical movement of the screed 5 . Actuator 2 above
1, the threaded rod 23, the inner cylinder 22, etc. constitute a vertical movement device 10 for the guide sensor 19.

The guide sensor 19 moves along a reference line (plane) 25, such as a wire or curbstone, provided beside the pavement roadbed (see FIG. 1). Guide sensor 19 controls the operation of pivot cylinder 8 . That is, the guide sensor 19 is connected to a solenoid valve 28 (FIG. 2) provided in the hydraulic circuit of the pivot cylinder 8.
) is electrically connected to the comparator 26 via an I/O (input-output) interface 27, so that even if the guide sensor 19 moves upward with respect to the reference line 25, the comparator 26
When a signal is output from When the opposite signal is output, the solenoid valve 28 operates so that the pivot cylinder 8 contracts and the support shaft 7 is raised.

In the above case, when the support shaft 7 descends, the inclination angle (attack angle) of the screed 5 becomes smaller and the pavement thickness becomes smaller, and when the support shaft 7 rises, the inclination angle of the screed 5 becomes larger and the pavement thickness becomes smaller. becomes larger.

A computing device 30 is connected to the first and second height sensors 13, 14, inclination sensor 15, and distance sensor 17 (see FIG. 2). The arithmetic device 30 includes an A/D (analog-to-digital) converter 31 that receives analog outputs from the height sensors 13 and 14 and the inclination sensor 15 and converts the analog outputs into digital outputs, and an A/D converter 31 and a distance An I/O interface 32 into which each digital output of the sensor 17 is input, and this I/O interface 3
2, and a data storage section 34 which inputs and stores numerical values obtained by the calculation section 33 and outputs them to the calculation section 33.

The arithmetic device 30 is configured such that the vehicle 1 has both height sensors 1
Height sensors 13, 1 every time the vehicle travels a distance of 3, 14.
4 and the measurement signals sent from the tilt sensor 15, necessary calculations are performed.

The main calculation contents of the calculation section 33 are: (1) Calculating the pavement thickness T from the height difference between two measurement points simultaneously measured by a pair of height sensors 13 and 14 and an inclination sensor 15; ■ Select a plurality of consecutive points from the pavement thickness T calculated above and calculate the average value Ta. ■
Calculating the difference ε between the calculated average pavement thickness Ta and the target pavement thickness T0. - Calculate the movement amount ΔS of the guide sensor 19 from the above difference ε according to the setting conditions stored in advance in the data storage unit 34, and issue a command to the actuator 21 via the I/O interface 34 based on the calculation result. , and move the guide sensor 19 up or down. The amount of movement of the guide sensor 19 is detected by the amount of movement sensor 24 and fed back to the calculation section 33 .

Here, two measurement points P1 are measured by a pair of height sensors 13 and 14 and an inclination sensor 15.
, P2 and the pavement thickness T will be explained based on FIGS. 4 and 5.

First, the height difference δ is approximately calculated using the following equation 1. δ=H2-(H1-MTanθ1)...(1)

002
1] Here, the above symbols have the following meanings. H1: Value H2 detected by the first height sensor 13
: Value M detected by the second height sensor 14 :
Distance between the first and second height sensors 13 and 14 (in FIG. 5) θ1: Inclination of measurement arm 12

Based on the height difference δ, the pavement thickness T is approximately calculated using the following equation 2. T=H21+δ−MTanθ2−H0……(2)

00
23] Here, the above symbols have the following meanings. H21: Value δ detected by the second height sensor 14
: Value M calculated using formula 1 above: Same as above θ2: Inclination of measurement arm 12 H0: Height difference between height sensor 14 and screed 5

00
24] Equations 1 and 2 above are shown to make it easier to understand how to calculate the height difference δ and pavement thickness T, and are not the same as those used by the measuring device 11 shown in the asphalt finisher AF shown in FIGS. 1 and 4. The difference is that the distance between the first and second height sensors is set to M/2 (one fraction of an integer) or the like in order to downsize the measurement arm.

Next, a method of controlling pavement thickness using the leveling machine constructed as described above will be explained. Road paving with Asphalt Finisher AF is performed by vehicle 1 in the same way as before.
While running at a constant speed, the asphalt mixture in the hopper 2 is sent to the screw by a feeder and spread uniformly in front of the screed 5, and the asphalt mixture is spread on the screed 5.

In the above, the traveling distance of the vehicle 1 is measured by the distance sensor 17, and the distance from the road surface is measured by the first and second height sensors 13, 14 and the inclination sensor 15 every time the traveling distance becomes M. It measures and outputs the measurement result to the arithmetic device 30.

The arithmetic unit 30 calculates the output signals of the height sensors 13 and 14, the distance sensor 17, and the inclination sensor 15.
The pavement thickness T is calculated as described above. From these values, the average value T of the pavement thickness at multiple consecutive measurement points on the existing paved surface
Calculate a. Then, the difference ε between the average value Ta and the preset target pavement thickness T0 is determined, and the vertical movement amount ΔS of the guide sensor 19 is calculated from the difference ε.
is activated to move the guide sensor 19 upward or downward by ΔS. The average value Ta is calculated every time the vehicle 1 travels a predetermined distance (for example, 5 m) or every predetermined time.

The guide sensor 19 moves along a reference line 25 such as a curb or a gutter, and controls the pivot cylinder 8 so that the screed 5 maintains a predetermined height difference from the reference line 25 and spreads the asphalt mixture evenly. .

[0029] The pavement roadbed is concave, and the average pavement thickness Ta is larger than the target pavement thickness T0, for example,
When the difference ε exceeds a predetermined upper limit, the arithmetic unit 3
0 activates the lifting device 10 to raise the guide sensor 19 relative to the screed 5 by the amount of movement ΔS corresponding to the value of the difference ε. As soon as the guide sensor 19 is raised, the pivot cylinder 8 is extended to reduce the angle of inclination of the screed 5. As a result, the pavement thickness becomes thinner than before and approaches the target device T0. If the paved roadbed is raised in a convex shape, the above operation is reversed.

[0030]

As explained above, the method for controlling pavement thickness in a leveling machine according to the present invention is such that a screed is provided at the rear of the vehicle, the inclination angle of which can be changed in the front and rear direction by means of an angle adjustment means. In front of the screed, a pair of height and inclination sensors that individually measure the distance to the pavement subgrade are installed at a required interval in the longitudinal direction. In a leveling machine that is electrically connected to a calculation device that calculates the paving thickness of asphalt mixture by a screed based on the measurement results of an inclination sensor, a reference line placed next to the paving roadbed is attached to the screed. A guide sensor that moves along the angle control means and controls the angle adjustment means is provided so as to be able to move up and down with a vertical device, and when the pavement thickness calculated by the calculation device deviates from a predetermined value, the calculation device operates the vertical device. The system is designed to control the pavement thickness by moving the guide sensor up or down relative to the screed so that the pavement thickness falls within the standard range.
The pavement thickness can be kept within a predetermined standard range, and the pavement can be made as flat as possible.

Furthermore, since the guide sensor is moved up and down by a calculation device, paving can be performed continuously without interruption, unlike when a worker manually moves the guide sensor up and down. Furthermore, by changing the setting conditions for the amount of movement of the guide sensor relative to the difference between the average pavement thickness and the target pavement thickness, it is possible to vary the importance ratio of flatness and pavement thickness, resulting in better paving. be able to.

[Brief explanation of drawings]

FIG. 1 is a side view of an asphalt finisher implementing the present invention.

FIG. 2 is a block diagram of a calculation device and a pivot cylinder control system.

FIG. 3 is a sectional view of the vertical device.

FIG. 4 is a layout diagram of a pair of height and inclination sensors, a guide sensor, etc.

FIG. 5 is an explanatory diagram for determining pavement thickness.

[Explanation of symbols]

1 Traveling vehicle 5 Screed 8 Pivot cylinder (angle adjustment means) 10 Vertical device 13, 14 Height sensor 15 Inclination sensor 19 Guide sensor 25 Reference line 30 Arithmetic device

Claims (1)

[Claims] Claim 1: A screed is provided at the rear of the vehicle, the inclination angle of which can be changed in the longitudinal direction by an angle adjustment means, and a pair of height and height heights are provided in front of the screed of the vehicle to individually measure the distance to the paved roadbed. Inclination sensors are provided at required intervals in the front-rear direction, and both height and inclination sensors are equipped with a calculation device that calculates the paving thickness of asphalt mixture by the screed based on the measurement results of both height and inclination sensors. In a leveling machine to which is electrically connected,
A guide sensor that moves along a reference line placed next to the pavement roadbed and controls the angle adjustment means is provided on the screed so that it can be moved up and down with a vertical device, and the pavement thickness calculated by the calculation device is set to a predetermined value. A leveling machine characterized in that when the value deviates from the value, the arithmetic unit operates a vertical device to move the guide sensor upward or downward relative to the screed to control the pavement thickness so that it falls within a reference range. Pavement thickness control method.