JPH1037124A - Asphalt finisher - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the width of pavement by automatically adjusting the position of an expansion screed based on the step difference of a road surface even in case of change of the width of pavement. SOLUTION: When hot mixed material is laid level in the width of a cut road surface 5, an expansion screed 17R is expanded/contracted so as to conform it to the road surface 5 width. At this time, the end part of the expansion screed 17R is conformed to the step difference position based on the step difference 33 formed by cutting. For the purpose, the step difference 33 position is detected from change of distance against the road surface by a step difference detecting means 27 provided on the end part position of the expansion screed 17R, and a control part 53 controls an expansion screed moving means 15 from the positional relation between the step difference 33 position and the step difference detecting means 27 so as to conform the end part of the expansion screed 17R to the step difference position. The step difference detecting means 29 is provided with distance sensors 25L, 25R, beam sensors, and the like, relation to the step difference 33 position is obtained from difference of distance to the detected road surface, and movement of the expansion screed 17R is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asphalt finisher, and more particularly, to an asphalt finisher capable of automatically expanding and contracting a telescopic screed based on a step of a cut road.

[0002]

2. Description of the Related Art In recent years, road traffic has become severely paved due to intensified automobile traffic, and thus maintenance and repair work on roads has been increasing. In this maintenance and repair work, there is a method of partially cutting a worn or rutted road surface to a certain depth, and paving and repairing that portion. In such a case, in order to reduce traffic congestion as much as possible, for example, on a two-lane road, construction is often performed while leaving one lane open.

At this time, an asphalt finisher used to spread the heated mixture is generally equipped with a telescopic screed whose pavement width can be freely changed. The change in the pavement width is performed by an operator.

[0004] Further, the finishing of the cutting portion pavement is generally performed by an operator holding a rake.

[0005]

However, in such a construction method, since the telescopic screed of the asphalt finisher is expanded and contracted by an operator, the telescopic screed can be accurately drawn along the cut boundary line. It is difficult to expand and contract the rake, and post-processing by a worker having a rake is absolutely necessary.

In this case, the lane adjacent to the lane to be constructed is opened for general traffic as described above, and the worker is forced to work in an extremely limited space adjacent to the open lane. There is a problem that there is a risk of encountering a traffic accident.

SUMMARY OF THE INVENTION An object of the present invention is to pay attention to the conventional technology as described above. Even if the pavement width changes, the position of the telescopic screed is automatically adjusted based on the step on the road surface. An object of the present invention is to provide an asphalt finisher capable of controlling a pavement width.

[0008]

To achieve the above object, an asphalt finisher according to the first aspect of the present invention moves a telescopic screed in the width direction of a pavement in order to spread a heated mixture on a cut road surface. An asphalt finisher for adjusting the pavement width by means of a telescopic screed moving means for moving the telescopic screed in the pavement width direction, and detecting a step indicating the pavement width provided at an outer end position in the pavement width direction of the telescopic screed. And a control unit that controls the telescopic screed moving means to adjust the outer end of the telescopic screed to the step position based on a signal from the level detecting means. Things.

Therefore, in order to spread the heated mixture on the cut road surface width, the stretchable screed is expanded and contracted to the pavement width to match the road surface width. At this time, the end of the elastic screed is adjusted to the position of the step with reference to the step formed by cutting. For this purpose, the step detecting means provided at the end position of the telescopic screed detects the step position from the change in the distance to the road surface, and the control unit detects the step position from the positional relationship between the step position and the step detecting means. To adjust the end of the telescopic screed to the step position.

[0010] In the asphalt finisher according to the second aspect of the present invention, the step detecting means according to the first aspect is provided at the outer end position in the pavement width direction of the telescopic screed or in front of the screed from the outer end portion via a bracket. And at least two distance sensors.

Therefore, at least two distance sensors provided at the outer end of the telescopic screed in the pavement width direction or at the front of the screed via the bracket from the outer end measure the distance to the road surface. The positional relationship between the step position and the end in the width direction of the screed is detected from the difference in the distance to the road surface detected by the sensor.

According to a third aspect of the present invention, there is provided an asphalt finisher, wherein the control unit according to the first aspect calculates the step position based on a distance to a road surface transmitted from the step detecting means; A comparison unit for comparing a positional relationship between the stepped position and the distance sensor, and a movement command unit for commanding the telescopic screed moving means by a signal from the comparison unit.

Therefore, the calculating section of the control section calculates the step position based on the distance to the road surface transmitted from the step detecting means, and the comparing section obtains the positional relationship between the step position and the distance sensor. The movement command unit controls the telescopic screed moving means on the basis of the signal from the controller to move the telescopic screed so that the end in the pavement width direction corresponds to the step position.

According to a fourth aspect of the present invention, there is provided an asphalt finisher, wherein the distance sensor according to the second or third aspect is an ultrasonic sensor.

Therefore, the distance to the road surface is accurately measured by the ultrasonic sensor.

According to a fifth aspect of the invention, there is provided an asphalt finisher, wherein the distance sensor according to the second or third aspect is a beam sensor.

Therefore, the distance to the road surface and the position of the step are detected by the beam sensor.

According to a sixth aspect of the present invention, in the asphalt finisher according to the first aspect, the step detecting means is provided at an outer end position in the pavement width direction of the telescopic screed and swings at least in the pavement width direction. It is characterized by comprising a free beam sensor.

Therefore, the step position is detected by swinging the beam sensor provided at the outer end in the pavement width direction of the telescopic screed and scanning.

According to a seventh aspect of the present invention, there is provided an asphalt finisher, wherein the control unit according to the first aspect calculates a step position from a swing angle when the step is detected by the step detecting means according to the sixth aspect; And a movement command unit for commanding the telescopic screed moving means based on the obtained step position.

Therefore, the calculating unit obtains the step position from the swing angle when the step is detected by the swinging beam sensor,
The movement command unit controls the movement of the telescopic screed based on the obtained step position.

According to an eighth aspect of the present invention, there is provided an asphalt finisher, wherein the control section according to the first aspect compares the distance signal to the road surface scanned by the step detecting means with the level difference to a high signal or a low signal. , An averaging unit for averaging the high signal and the low signal, an arithmetic unit for obtaining a distance from the average value obtained by the averaging unit, and a distance between the obtained level difference And a movement command unit for commanding the telescopic screed moving means based on the following.

Therefore, the distance to the road surface scanned by the oscillating beam sensor is represented by a high signal and a low signal by the binary comparator, and the high signal and the low signal are averaged by the averaging unit. The calculation unit calculates the distance to the step from the average value. The movement command unit controls the movement of the telescopic screed based on the obtained distance.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIGS. 13 and 14 show the entire asphalt finisher 1 according to the present invention.
The main body of the asphalt finisher 1 is already well known, and only the outline thereof will be described below.

The asphalt finisher 1 has, for example, a caterpillar 3 as a traveling device, and moves on a road surface 5 that has been pretreated by the caterpillar 3. Further, a hopper 7 is provided on the front side (the right side in FIG. 14) for receiving asphalt mixture, which is a heated mixture for paving carried by a dump truck. A bottom portion of the hopper 7 is open, and a bar-conveyor-shaped bar feeder 9 extending rearward is provided below the hopper 7. The bar feeder 9 conveys the asphalt mixture supplied to the hopper 7 to the rear of the asphalt finisher 1.

An auger 11 is provided at the rear of the asphalt finisher 1 to rotate the asphalt mixture AG, which has been transported by the bar feeder 9 and dropped onto the road surface 5 by rotating, to spread left and right uniformly. It has become.

The asphalt finisher 1 has a main screed 13 in the center of the rear surface on which the asphalt mixture is spread right and left. On both left and right sides (upper and lower sides in FIG. 14), there are extendable screeds 17L and 17R which can be expanded in the left and right directions by an extendable screed moving means 15 (see FIG. 1).

The main screed 13 and the left and right telescoping screeds 17L and 17R are swingably connected around a pin 21 via leveling arms 19 provided on both side surfaces of the asphalt finisher 1.

The main screed 13 and the left and right telescoping screeds 17L, 17R are in a state of floating on the asphalt on the pavement surface. The thickness of the paved road surface before the road roller is applied and finally hardened,
Main screed 13 and left and right telescopic screeds 17
It is determined by adjusting the height of L and 17R.

The height is adjusted by changing the inclination angles of the main screed 13 and the left and right telescopic screeds 17L and 17R by controlling a working cylinder (not shown) engaged with the front end of the leveling arm 19. Done.

Accordingly, the asphalt mixture expanded by the auger 11 is heated and pressed by the base plate (not shown) provided on the lower surfaces of the main screed 13 and the left and right telescopic screeds 17L and 17R, and is pressed and paved. Spread across the width. In the case where both slopes are formed on the road surface, the main screed 13 is bent by a crown 23 (for example, a turnbuckle) at the center of the main screed 13 to make a slope.

On the other hand, referring also to FIG. 2, the telescopic screed 17 (hereinafter referred to as the right telescopic screed 17R)
Above each of the outer end surface positions, a step detecting head 27 as a step detecting means having a pair of distance sensors 25L and 25R using, for example, ultrasonic waves is provided. A control box 29 for controlling the movement of the step detecting head 27 and the telescopic screed 17 in the direction of the pavement width is provided near the driver's seat 31.

Next, the principle of detecting the step 33 by the step detecting head 27 will be described with reference to FIGS. The two distance sensors 25L and 25R are provided at the same height position, and are provided at right angles to the step 33, that is, at right angles to the traveling direction. The intermediate point P0 between the two distance sensors 25L, 25R is
Are provided so as to correspond to the vicinity of the outermost position.

For example, in the step detecting head 27 provided on the right telescopic screed 17, the left distance sensor 25L in FIG. 2 indicates a certain distance (ie, height) from the road surface, but the right distance Sensor 25R has step 3
The amount varies depending on the amount of (3).

That is, referring to FIG. 3, considering the difference between the heights of the two distance sensors 25L and 25R, the distance becomes zero when the two are the same height. If it is located above, a difference of (La-Lb) occurs. Therefore, the difference between the detected heights is (La−Lb)
The point which becomes / 2 is set as the neutral point NP, and this neutral point is adjusted to the outermost position of the telescopic screed 17, for example.

Thus, the difference in height is Δ (La−Lb)
/ −Δ｝, an extension signal is issued to extend the telescopic screed 17, and the height difference is ｛(La−L).
b) Telescopic screed 1 if greater than / 2 + Δ｝
7. A reduction signal is issued so as to reduce the number 7. Where 2 · Δ
Indicates the width of a dead zone (see FIG. 3) in consideration of the unevenness of the step 33, the accuracy of the movement of the asphalt finisher 1, and the like, and means a position where the neutral point NP is determined to be at the position of the step 33. I have.

FIG. 4 shows an example of a control panel 35 provided on the surface of the control box 29 for performing the above-described detection operation. On the upper part of the control panel 35, a display 3 made of, for example, a CRT or a liquid crystal display panel
7, the reflection distances La and Lb and the step setting value Ls are displayed.

A step setting dial 39 and a dead zone setting dial 41 are provided at a central portion of the control panel 35, between which a leftward lamp 43L and a rightward lamp 4 are provided.
An operation lamp 43 having 3R is provided.

An input changeover switch 45 is provided below the input switch 45 for selecting which of the left and right steps 33 in the traveling direction is the target. An output changeover switch 47 for setting in which direction to move is provided. Power switch 4 for turning on / off the power
9 and an alarm lamp 51 for notifying an abnormal time.

Next, the configuration of the telescopic screed control device 53 as a control unit provided inside the control box 29 will be described with reference to FIG.

In the step detecting head 27, the left and right steps 33 are provided.
Has two step detecting heads 27 to cope with
The step detecting head 27 is connected to a detecting head control board 55, and selects the left step or the right step 33 (not shown) by the input switch 45.

Each step detecting head 27 is provided with an ultrasonic transmission / reception unit 57L, 57R, and transmits a transmission timing pulse (SEN) from the detection head control board 55.
Upon receiving D), the piezoelectric element 59 emits impact ultrasonic waves. When the piezoelectric element 59 receives an ultrasonic wave, the ultrasonic transmission / reception units 57L and 57R receive a reception trigger pulse (REC).
Is transmitted to the detection head control board 55.

As described above, the detection head control board 55 converts the reciprocating time (proportional to the reflection distance) until the ultrasonic wave emitted on the road surface 5 as an object is received into an analog (or digital) signal. Then, it is transmitted to the telescopic screed control device 53.

The expansion / contraction screed control device 53 is provided with a subtraction circuit 61 as an arithmetic unit. The subtraction circuit 61 receives the reflection distances La and Lb from the detection head control board 55 and obtains the difference between them. Proximity signal comparator 6
3 and the backward signal comparator 65. Further, the subtraction circuit 61 sends the reflection distance La to the display 37 for display.

The step setting dial 39 is used to detect the step 33 to be detected.
The step setting dial (39) provided on the control panel 35 described above.
Is set by The step setting value Ls set by the step setting dial 39 is displayed on the display 37 of the control panel 35 and transmitted to the dead zone setting dial 41.

The dead zone setting dial 41 has a step setting value Ls.
Is calculated, and 50 ± Δ (%) is calculated. That is, “Ls / 2−Δ” and “Ls / 2 + Δ” are calculated using Δ (0 to 40%) adjusted by the dead zone setting dial 41 provided on the control panel 35, and “Ls / 2” is calculated. −Δ ”is transmitted to the proximity signal comparator 63, and“ Ls / 2 + Δ ”is transmitted to the backward signal comparator 65 which is a comparison circuit.

The proximity signal comparator 63 compares “La−Lb” from the subtraction circuit 61 with “Ls / 2−Δ”, and outputs a proximity signal when “Ls / 2−Δ”> “La−Lb”. It is issued to a drive circuit 67 as a movement command unit.

The backward signal comparator 65 compares “La−Lb” from the subtraction circuit 61 with “Ls / 2 + Δ”, and outputs a backward signal to the drive circuit 67 when “Ls / 2 + Δ” <“La−Lb”. Emit.

Upon receiving the approach signal, the drive circuit 67 turns on, for example, the rightward lamp 43R of the control panel 35 and drives the telescopic screed moving means 15 with the power from the power source 69 to extend the telescopic screed 17 (here, the right side). To). Alternatively, in response to the retreat signal, the leftward lamp 43L of the control panel 35 is turned on, and the telescopic screed moving means 15 is driven by the electric power from the power source 69 to reduce the telescopic screed 17 (here, move it to the left). When an abnormality in the external device is detected, for example, in the case of an overload or the like, the alarm lamp 51 of the control panel 35 is turned on to give a warning.

From the above results, when the pavement width changes, the step 33 indicating the pavement width is automatically detected, and this step 3
Since the extendable screed 17 can be expanded and contracted in accordance with the three positions, a screed width corresponding to the pavement width can always be obtained. Accordingly, it is not necessary for the worker to perform processing with a rake or the like, and work safety is improved.

Next, a case where a beam sensor is used will be described with reference to FIGS.

First, referring to FIG. 5, a step detecting head 71 is provided above and behind the outer end face of each of the telescopic screeds 17 (see FIG. 14). The step detecting head 71 has a central beam sensor 73C and left and right beam sensors 73L, 73R with the beam sensor 73C interposed therebetween.
Is provided.

The beam sensors 73C, 73L, 73R
Is a beam B from above in the vicinity of the step 33 and vertically downward.
M is irradiated to measure the distance to the road surface. Therefore, the distance measured by the beam sensors 73L and 73R is a binary value of the higher h (+) and the lower h (-).

From this, hN = (h (+) + h (-))
/ 2 is set as the reference height, and the step position can be detected by comparing the distance h detected by the beam sensor 73C with the reference height hN.

That is, when the distance h measured by the beam sensor 73C provided at the center of the step detecting head 71 is higher than the reference height hN, the beam sensor 7
Since it is detected that the position of 3C is on the left side of the step 33 in FIG. 5, the telescopic screed 17 needs to be extended. On the other hand, when it is lower than hN, the beam sensor 7
Since 3C is detected to be on the right side of the step in FIG. 5, it is necessary to shrink the elastic screed 17.

As described above, the beam sensor 73
The step detecting head 71 provided with the C, 73L, 73R vertically downward can also determine which direction the telescopic screed 17 is displaced from the step 33, so that the telescopic screed 17 can be easily moved to the step 33. Can be adjusted to the position.

FIG. 6 shows an oscillating step detecting head 7 for temporally oscillating the beam sensor 75 in the direction crossing the road.
7 is shown. In the step detecting head 77, basically, the position of the step 33 is determined by obtaining the distance to the road surface using the beam sensor 75 in the same manner as the step detecting head 71 described above.

In the step detecting head 77, when the step detecting head 77 is mounted on the telescopic screed 17, the beam B
It is difficult to set the beam sensor 75 so that M (see FIG. 5) is completely vertically downward, and the purpose of detecting the step 33 by the step detecting head 77 is to set the end of the telescopic screed 17 to the step 33. This is in consideration of positioning.

That is, since the purpose is to move the telescopic screed 17 to the left and right to adjust the beam sensor 75 to the position of the step 33, the shift amount and direction of the step 33 and the beam sensor 75 are detected. .

The principle of measuring the position of the step 33 in the swing type step detecting head 77 will be described with reference to FIG. FIG. 7A shows a change in the swing angle θ of the beam sensor 75 with respect to time t in a state where the beam sensor 75 is located slightly before the step 33 (left side in FIG. 6). Shows the measured distance h corresponding to the swing angle θ with respect to the time axis t.

In this case, the step 33 is detected when the swing angle θ is + θx, so that the distance h detected at tx is h
(-) And h (-) reciprocating until it becomes + θx again
Becomes After that, when the swing angle θ further decreases, the distance h is removed from the step 33 again, so that the detected distance h becomes h (+).

Therefore, the deviation ΔX of the beam sensor 75 from the step 33 is shifted by the time tx, so that the step 33
ABS (ΔX) ≒ h (−) · sin
(2π · tx / T). Here, T indicates a cycle in which the beam sensor 75 swings.

In this way, the absolute value ABS (ΔX) of the distance from the step 33 can be detected.
Since the left or right side of 3 is easily known from the swinging direction of the beam sensor 75, the moving direction and the moving amount of the telescopic screed 17 can be obtained.

Next, referring to FIG.
The case where three positions are controlled will be described.

In the state shown in FIG. 8, the beam sensor 7
This indicates that the step 33 was detected when the swing angle of No. 5 was θx. Therefore, when the beam sensor 75 is located on the left side of the left side position PL shown in FIG. 8, an approach signal is issued to extend the telescopic screed 17. On the other hand, when the beam sensor 75 is located on the right side of the right side position PR shown in FIG. 8, a backward signal is issued to reduce the length of the telescopic screed 17.

Therefore, between the approach signal and the retreat signal in FIG. 8, the control signal is turned off by interpreting that the telescopic screed 17 is at the desired position, and the telescopic screed 17 is not moved. The value of ΔX corresponds to an overshoot value when the approach or retreat signal is turned off.

It should be noted that θx needs to be variable because it changes depending on the step value h (−) even if h (+) is fixed.
In calculation, ΔX = h (−) · tan θx.

Next, a case where the control of the telescopic screed 17 is performed by PWM control will be described with reference to FIGS.

Referring to FIG. 10, the step detecting head 79 is provided with a beam sensor 81 that swings in the cross direction of the road, similarly to the step detecting head 77 shown in FIG.

Since the beam sensor 81 oscillates at a period T, the oscillating angle θ of the beam BM is shown in FIG.
It changes like The beam sensor 81 emits an L signal when detecting the upper side of the step (right side of the step 33 in FIG. 10), and outputs an H signal when detecting the lower side (left side of the step 33 in FIG. 10). .

Therefore, when the beam sensor 81 is located almost directly above the step (point P0 in FIG. 10), the pulse widths of the H signal and the L signal are substantially equal as shown in the upper part of FIG. 9B. Become.

On the other hand, when the beam sensor 81 is on the right side of the step 33 (point P1 in FIG. 10), the pulse width of the L signal is longer than that of the H signal (middle of FIG. 10B). Also,
The beam sensor 81 is located on the left side of the step 33 (P1 'in FIG. 10).
In this case, the pulse width of the H signal is longer than that of the L signal (lower part in FIG. 10B).

When the beam BM of the beam sensor 81 does not fall on the step 33 (points P2 and P2 'in FIG. 10), the signal becomes a continuous H signal or L signal through a cycle T, though not shown.

Referring to FIG. 11, when the pulse widths of the L signal and the H signal are averaged with respect to the period T, when the pulse width is just above the step 33, the neutral PN (that is, the pulse width of the L signal and the pulse width of the H signal) are obtained. However, if it is shifted to the left or right, a proportional band width 83 that changes from L to H with a certain width instead of zero can be obtained, so that PWM control can be performed using this data. Become.

Next, a telescopic screed control device 85 as a control unit for performing PWM control will be described with reference to FIG.

In the step detecting head 79 (see FIG. 10),
A step detecting head 79 is provided to correspond to the left and right steps 33, and the step detecting head 79 has a beam sensor 81 with a scanner.

This beam sensor 81 is connected to a comparator 87 which is a binary comparator that emits an H signal or an L signal. The comparator 87 is also connected to an adjuster 89 for setting a distance LT, and compares the set distance LT with a measured distance Lθ from the beam sensor 81. The comparator 87 is connected to an integrating circuit 91 for averaging the H signal and the L signal, and the integrating circuit 91 generates transverse direction data EW (see FIG. 13). Note that EN indicates a neutral position, which means that the beam sensor 81 is located directly above the step 33.

The transverse data EW and the neutral value EN generated by the integration circuit 91 are calculated by the arithmetic circuit 9
3, 95. The arithmetic circuits 93 and 95 each have α
(EW-EN) and .alpha. (EN-EW) are obtained, and the obtained values are referred to as the approach comparator 97 and the backward comparator 9 respectively.
9 Here, α is a constant having an appropriate value.

The approach comparator 97 and the backward comparator 99 are connected to a saw-tooth wave generator 103 which can be adjusted by the adjuster 101 so that the impression can be adjusted. Therefore, in each of the comparators 97 and 99, the transverse direction data EW deviates from the neutral value EN by a certain value or more based on the value obtained by the above-mentioned arithmetic circuits 93 and 95 corresponding to the period of the sawtooth wave whose sensitivity has been adjusted. In this case, the approach signal or the backward signal is sent to the drive circuits 105 and 107, and the telescopic screed 17 is moved by the motor 109.

From the above results, when the pavement width changes, the step 33 indicating the pavement width is automatically detected, and this step 3
Since the extendable screed 17 can be expanded and contracted in accordance with the three positions, a screed width corresponding to the pavement width can always be obtained. Accordingly, it is not necessary for the worker to perform processing with a rake or the like, and work safety is improved.

The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes. That is, in the above-described embodiment, the case where the step 33 is on the right side in the pavement width direction has been described, but the same applies to the case where the step is on the left side.

The arrangement of the switches and the like on the control panel 35 is not limited to the illustrated one.

[0084]

As described above, in the asphalt finisher according to the first aspect of the present invention, when the heated mixture is spread over the cut road surface width, the step difference provided at the end position of the telescopic screed is detected. The means detects the step position by cutting from the change in the distance to the road surface, and the control unit controls the telescopic screed moving means from the positional relationship between the step position and the step detecting means, and automatically moves the end of the telescopic screed to the step position. In order to match, even when the pavement width changes, the screed width corresponding to the pavement width can be automatically set. As a result, the worker does not have a step of leveling with a rake or the like, so that the safety of work can be ensured even when the adjacent lane is open for general traffic.

In the asphalt finisher according to the second aspect of the present invention, at least two distance sensors provided in front of the screed from the outer end in the direction of the pavement width of the telescopic screed or from the outer end to the road surface are provided. By measuring the distance between the steps and comparing the distances to the road surface detected by the distance sensors, it is possible to detect the positional relationship between the step position and the end of the telescopic screed in the width direction of the pavement.

In the asphalt finisher according to the third aspect of the present invention, the calculating unit of the control unit calculates the step position based on the distance to the road surface transmitted from the step detecting means, and determines the positional relationship between the step position and the distance sensor. The pavement width changes because the comparison part obtains and the movement command part controls the telescopic screed moving means based on the signal from the comparison part to move the end of the telescopic screed in the pavement width direction corresponding to the step position. In such a case, the telescopic screed can be automatically moved to a screed width corresponding to the pavement width.

In the asphalt finisher according to the fourth aspect of the invention, by using an ultrasonic sensor as the distance sensor, the distance to the road surface can be accurately measured.

In the asphalt finisher according to the fifth aspect of the present invention, the distance to the road surface and the position of the step can be accurately detected by using the beam sensor.

In the asphalt finisher according to the sixth aspect of the present invention, the beam sensor provided at the outer end in the width direction of the pavement of the telescopic screed is swung in the width direction for scanning, so that the step position can be reliably detected. Can be.

In the asphalt finisher according to a seventh aspect of the present invention, the arithmetic unit determines the step position from the swing angle when the step is detected by the swinging beam sensor, and the movement command unit expands and contracts based on the determined step position. Since the movement of the screed is controlled, the telescopic screed can be adjusted to the step position.

In the asphalt finisher according to the present invention, the distance to the road surface scanned by the oscillating beam sensor is represented by a high signal and a low signal by a binary comparator, and the high signal and the low signal are averaged. Are averaged, the calculation unit obtains the distance to the step from the obtained average value, and the movement command unit controls the movement of the telescopic screed based on the obtained distance, so that the telescopic screed can be adjusted to the step position. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control device for controlling the movement of a telescopic screed of an asphalt finisher according to the present invention.

FIG. 2 is an explanatory diagram of the principle of step detection by a step detection head.

FIG. 3 is a graph showing a difference in reflection distance detected by a step detecting head.

FIG. 4 is an explanatory diagram showing a control panel of a control box.

FIG. 5 is an explanatory diagram showing a state where a step position is detected by a beam sensor.

FIG. 6 is an explanatory diagram showing a state in which a step position is detected by swinging a beam sensor.

FIG. 7 is a graph showing a temporal relationship between a change in the swing angle of the beam sensor and a distance detected by the beam sensor.

FIG. 8 is an explanatory view showing a state in which the telescopic screed is controlled at three positions.

FIG. 9 is a graph showing a temporal relationship between a swing angle and a detection signal when performing PWM control on a telescopic screed.

FIG. 10 is an explanatory diagram showing a state of distance measurement in PWM control.

FIG. 11 is a graph showing a proportional bandwidth obtained by averaging the H signal and the L signal.

FIG. 12 is a block diagram illustrating a configuration of a telescopic screed control device that performs PWM control.

FIG. 13 is a side view of the asphalt finisher according to the present invention.

FIG. 14 is a plan view of the asphalt finisher according to the present invention.

[Explanation of symbols]

Reference Signs List 1 asphalt finisher 5 road surface 15 telescopic screed moving means 17 telescopic screed 25 distance sensor 27, 71, 77, 79 step detecting head (step detecting means) 53 control device (control unit) 61 subtraction circuit (calculating unit) 63 proximity signal comparator ( Comparison section) 65 Backward signal comparator (Comparison section) 67, 105, 107 Drive circuit (Motion command section) 73, 75, 81 Beam sensor (Distance sensor) 87 Binary comparator 91 Integrator circuit (Averaging section) 93, 95 Calculation Circuit (arithmetic unit)

Claims (8)

[Claims] 1. An asphalt finisher for adjusting a pavement width by moving a telescoping screed in a pavement width direction to spread a heated mixture on a cut road surface, wherein the telescoping screed is moved in a pavement width direction. A screed moving means, a step detecting means provided at an outer end position in the pavement width direction of the telescopic screed to detect a step indicating the paving width, and an outer end of the telescopic screed based on a signal from the step detecting means. A controller for controlling the telescopic screed moving means so as to match the step position. 2. The method according to claim 1, wherein the step detecting means is provided at an outer end of the telescopic screed in a pavement width direction or in front of the screed via a bracket from the outer end, and has at least two distance sensors. The asphalt finisher according to claim 1, wherein 3. The control section calculates a step position based on a distance to a road surface transmitted from the step detecting means, and calculates a positional relationship between the calculated step position and the distance sensor. 2. The asphalt finisher according to claim 1, further comprising: a comparison unit for comparison; and a movement command unit for commanding the telescopic screed moving means based on a signal from the comparison unit. 4. The asphalt finisher according to claim 2, wherein said distance sensor is an ultrasonic sensor. 5. The asphalt finisher according to claim 2, wherein said distance sensor is a beam sensor. 6. The method according to claim 1, wherein the step detecting means is provided at an outer end position of the telescopic screed in a pavement width direction, and is provided with a swingable beam sensor for scanning at least in the pavement width direction. The asphalt finisher according to claim 1, wherein 7. A control unit for calculating a step position from a swing angle when a step is detected by the step detecting means according to claim 6, and the telescopic screed based on the obtained step position. The asphalt finisher according to claim 1, further comprising: a movement command unit that commands a moving unit. 8. A binary comparator for comparing a distance signal to a road surface scanned by the step detecting means according to claim 6 with a step to generate a high signal or a low signal, and the high signal and the low signal. An averaging unit for averaging the signal, an arithmetic unit for calculating a distance from the average value obtained by the averaging unit, and a movement instructing the telescopic screed moving means based on the obtained distance from the level difference Command part,
The asphalt finisher according to claim 1, further comprising: