JPH0781242B2 - Pavement thickness control method for leveling machine - Google Patents

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 a leveling machine such as an asphalt finisher.

[0002]

2. Description of the Related Art Conventionally, as a pavement thickness control method, there is a method of controlling the pavement thickness based on a curb or gutter on the side of a road to be paved, a wire stretched between two points, or the like. There is known a method of measuring the pavement thickness by means and controlling the pavement thickness based on the measurement result.

[0003]

The former method attaches importance to the flatness of the pavement. For example, when a wire is stretched linearly between two points and used as a reference for the pavement, the pavement between the two points is Even if the roadbed has large irregularities, it will be paved regardless of it, and the pavement will be finished flat, but the thickness will vary greatly depending on the irregularities of the roadbed.

The latter method, contrary to the former method,
The pavement thickness is uniform, but there is a problem that it will not be flat if the roadbed has irregularities.

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

[0006]

In order to achieve the above object, the present invention provides a screed at the rear portion of a vehicle whose angle of inclination in the front-rear direction can be changed by angle adjusting means, the front of the screed of the vehicle being provided. A pair of height and inclination sensors for individually measuring the distance to the paved roadbed are provided at required intervals in the front-rear direction, and both height and inclination sensors measure the height and inclination sensors. In a leveling machine to which a computing device for computing the pavement thickness of the asphalt mixture based on the screed is electrically connected, move to the screed along a reference line arranged beside the paved roadbed However, a guide sensor for controlling the angle adjusting means is provided vertically by the lifting device, and when the pavement thickness calculated by the computing device deviates from a predetermined value, the computing device operates the lifting device. It is allowed to move up or down the guide sensor against screed and was configured to control so as paving thickness falls within the reference range.

[0007]

In pavement, the pair of height sensors individually measure the distance to the pavement base, and the arithmetic unit calculates the pavement thickness based on the measurement results of the height and the inclination sensor. Further, the guide sensor moves along the reference line and controls the angle adjusting means of the screed.

In the above operation, when the pavement thickness becomes larger than a predetermined upper limit value, for example, the arithmetic unit operates the up-down device to raise the guide sensor with respect to the screed, and the pavement thickness is When it becomes smaller than a predetermined lower limit value, the vertical device is operated to lower the guide sensor with respect 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. The vertical movement of the guide sensor with respect to the screed is automatically performed by the computing device,
Unlike the case where the worker manually moves the guide sensor up and down, paving can be continuously performed without interruption.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The attached drawings show an example of an asphalt finisher embodying the present invention. In the drawings, reference numeral 1 is a traveling vehicle of an asphalt finisher AF. At its front part, a hopper 2 is provided for putting the asphalt mixture. 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 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 traveling vehicle 1. The support shaft 7 is vertically moved by a pivot cylinder (angle adjusting means) 8. The basic structure of the asphalt finisher AF is well known.

Reference numeral 11 is a measuring device provided on each of the left and right sides. The measurement device 11 includes a first height sensor 13 provided at the tip of the measurement arm 12 and a second height sensor 13 provided at the center of the measurement arm 12 and forming a pair with the first height sensor 13. 14 and a tilt sensor 15 for measuring the tilt angle of the measuring arm 12. The base end (right end in FIG. 1) of the measuring arm 12 is supported by the frame body 5a supporting the screed 5, whereby the measuring arm 12 tilts together with the screed 5.

Although various types of first and second height sensors 13 and 14 are conceivable, a sensor utilizing ultrasonic waves is used here. Further, as shown in FIG. 4, the distance M between the two sensors 13 and 14 is equal to the second height sensor 14
Is set to 1/2 of the distance between the screed 5 and the rear end of the screed 5, and the relative height H ₀ of both sensors 13 and 14 with respect to the screed 5 is always a constant value. (See FIG. 5). Reference numeral 17 is a distance sensor provided at the lower end of the front part of the traveling vehicle 1 for calculating the traveling distance.

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 on the outer cylinder 20,
An inner cylinder 22 is inserted into the outer cylinder 20 so as to be free to rotate in the circumferential direction and to be vertically movable. A screw rod 23 is coupled to the output shaft of the actuator 21 and is 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
The screw rod 23 is rotated by 1 to move up and down with respect to the screed 5 together with the inner cylinder 22. The outer cylinder 20 has a guide sensor 19
A movement amount sensor 24 for detecting the amount of vertical movement of the screed 5 is attached. The actuator 2
1, the screw rod 23, the inner cylinder 22 and the like constitute a vertical device 10 for the guide sensor 19.

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

In the above, when the support shaft 7 descends, the inclination angle (attack angle) of the screed 5 decreases and the paving thickness decreases, and when the support shaft 7 rises, the screed 5 inclination angle increases and the paving thickness increases. Grows larger.

An arithmetic unit 30 is connected to the first and second height sensors 13, 14, the inclination sensor 15, and the distance sensor 17 (see FIG. 2). The arithmetic unit 30 receives an analog output of the height sensors 13 and 14 and the tilt sensor 15 and converts the analog output into a digital output, an A / D (analog-digital) converter 31, the A / D converter 31 and a distance. An I / O interface 32 to which each digital output of the sensor 17 is input, and this I / O interface 3
It is composed of an arithmetic unit 33 which performs an arithmetic operation based on the data from 2, and a data storage unit 34 which inputs and stores the numerical value obtained by the arithmetic unit 33 and outputs the numerical value to the arithmetic unit 33.

In the arithmetic unit 30, the vehicle 1 has both height sensors 1.
Each time the vehicle travels a distance of 3, 14, the height sensor 13, 1
4 and required measurement based on the measurement signal sent from the tilt sensor 15.

The main calculation content of the calculation unit 33 is to calculate the pavement thickness T from the height difference between two measurement points simultaneously measured by the pair of height sensors 13 and 14 and the inclination sensor 15. Select a plurality of consecutive points from the calculated pavement thickness T and calculate the average value Ta thereof. Difference ε between the calculated average pavement thickness Ta and the target pavement thickness T ₀
To calculate. The movement amount ΔS of the guide sensor 19 is calculated from the above difference ε according to the setting condition stored in advance in the data storage unit 34, and the actuator 21 is instructed via the I / O interface 34 based on the calculation result. To move the guide sensor 19 up or down. The movement amount of the guide sensor 19 is detected by the movement amount sensor 24 and is fed back to the calculation unit 33.

Here, a method for calculating the height difference δ between the two measurement points P ₁ and P ₂ measured by the pair of height sensors 13 and 14 and the inclination sensor 15, and the pavement thickness T
A method of calculating is described with reference to FIGS. 4 and 5.

First, the height difference δ is approximated by the following formula 1. δ = H ₂ − (H ₁ −M Tan θ ₁ ) ... (1)

The above-mentioned symbols have the following meanings. H ₁ : value detected by the first height sensor 13 H ₂ : value detected by the second height sensor 14 M: distance between the first and second height sensors 13 and 14 (FIG. 5) ) Θ ₁ : Inclination of the measuring arm 12

The pavement thickness T is approximately calculated by the following equation 2 based on the height difference δ. T = H ₂₁ + δ-M Tan θ ₂ -H ₀ (2)

The above symbols have the following meanings. H ₂₁ : Value detected by the second height sensor 14 δ: Value calculated by the above formula 1 M: Same as above θ ₂ : Inclination of the measuring arm 12 H ₀ : Height sensor 14 and screed 5 Difference in height

The above equations 1 and 2 are the difference in height δ and the pavement thickness T.
It is shown to make the calculation method of
Also, the distance between the first and second height sensors is set to M / 2 (an integer) for the purpose of downsizing the measuring arm and the like, which is slightly different from that by the measuring device 11 shown by the asphalt finisher AF shown in FIG. 1) and so on.

Next, a method for controlling the pavement thickness by the leveling machine constructed as described above will be described. Road paving with the asphalt finisher AF is the same as the conventional vehicle 1
While traveling at a constant speed, the asphalt mixture in the hopper 2 is fed to the screw by the feeder and spread evenly 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 roadbed surface is measured by the first and second height sensors 13 and 14 and the inclination sensor 15 every time the traveling distance becomes M. It measures and outputs the measurement result to the arithmetic unit 30.

The arithmetic unit 30 calculates from 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 a plurality of continuous measurement points on the existing pavement surface
Calculate a. Then, the difference ε between the average value Ta and the preset target pavement thickness T ₀ is calculated, and the vertical movement amount ΔS of the guide sensor 19 is calculated from the difference ε to calculate the vertical movement device 10.
Is operated to move the guide sensor 19 up or down 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 the 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. .

The pavement base is concave and the average pavement thickness Ta becomes larger than the target pavement thickness T0.
When the difference ε exceeds a predetermined upper limit, the arithmetic unit 3
When 0, the up-and-down device 10 is operated to raise the guide sensor 19 with respect to the screed 5 by the movement amount ΔS corresponding to the value of the difference ε. As soon as the guide sensor 19 is raised, the pivot cylinder 8 extends to reduce the inclination angle of the screed 5. As a result, the pavement thickness becomes thinner than before, and approaches the target equipment T ₀ . If the pavement is raised in a convex shape, the above operation is reversed.

[0030]

As described above, the pavement thickness control method for a leveling machine according to the present invention is provided with a screed at the rear portion of the vehicle, the screed of which the inclination angle in the front-rear direction can be changed by the angle adjusting means. In front of the screed of, a pair of height and inclination sensors for individually measuring the distance to the paved roadbed are provided at required intervals in the front-rear direction. In a leveling machine electrically connected to a computing device for computing the pavement thickness of asphalt mixture by screed based on the measurement result of the inclination sensor, in the screed, a reference line arranged beside the paved roadbed A guide sensor, which moves along the vertical axis and controls the angle adjusting means, is provided by an up-and-down device so as to be vertically movable. In actuating the upper and lower device move up or down the guide sensor against screed, because pavement thickness is configured to control to fit within the reference range,
The pavement thickness can be kept within a predetermined reference range, and pavement can be performed as flat as possible.

Further, since the guide sensor is moved up and down by the arithmetic unit, unlike the case where an operator manually moves the guide sensor up and down, paving can be continuously performed without interruption. Moreover, by changing the setting condition of the movement amount of the guide sensor with respect to the difference between the average pavement thickness and the target pavement thickness, it is possible to variously change the ratio of the importance of the flatness and the pavement thickness, and to perform better pavement. be able to.

[Brief description of drawings]

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

FIG. 2 is a block diagram of an arithmetic unit and a pivot cylinder control system.

FIG. 3 is a cross-sectional view of a vertical device.

FIG. 4 is a layout view of a pair of height and tilt sensors, a guide sensor, and the like.

FIG. 5 is an explanatory diagram for obtaining a pavement thickness.

[Explanation of symbols]

 DESCRIPTION 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 Computing device

Claims (1)

[Claims] 1. A screed provided at the rear part of the vehicle, the angle of which can be changed by the angle adjusting means.
In front of the screed of the vehicle, a pair of height and inclination sensors for individually measuring the distance to the paved roadbed are provided at required intervals in the front-rear direction. In a leveling machine electrically connected to a computing device for computing the pavement thickness of the asphalt mixture material by the screed based on the measurement result of the height and inclination sensor, the screed is disposed beside the paved roadbed. A guide sensor that moves along the reference line to control the angle adjusting means,
If the pavement thickness calculated by the above computing device deviates from the predetermined value, the above and below device is operated to move the guide sensor up or down with respect to the screed to provide paving A pavement thickness control method for a leveling machine, which is characterized in that the thickness is controlled to fall within a reference range.