JP2006161421A - Back pressure changing mechanism of screed lift cylinder for road paving machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a back pressure changing mechanism of screed lift cylinders for a road paving machine, which ensures the flatness of a pavement surface and the uniformity of pavement density even if a paving width of a screed is changed during execution of paving work. <P>SOLUTION: The back pressure changing mechanism is formed of a paving width detecting means 17 for detecting the paving width of the expandable screed 6, and a back pressure adjusting means for adjusting the back pressure of the lift cylinders 7, 8 so as to be increased/decreased depending on increase/decrease of the paving width detected by the paving width detecting means 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a variable back pressure mechanism for a screed lift cylinder in a road paving machine, and in particular, it is possible to ensure flatness of an asphalt pavement surface even if the pavement width of the screed is changed during pavement work. The present invention relates to a back pressure variable mechanism for a screed lift cylinder in a road paving machine.

  A conventional road paving machine will be described with reference to FIG. 4 by taking a wheel traveling asphalt finisher as an example. The asphalt finisher 1 is provided with a hopper 3 at the front part of the machine body 2, and the asphalt mixture received by the hopper 3 is conveyed to the rear part of the machine body 2 by a conveyor (not shown). The composite material is configured to be spread on the pavement surface with a screed having the following mechanism after the screw 4 has been expanded to the working width.

  The screed mechanism will be described. A pair of leveling arms 5 are mounted on both sides of the machine body 2 so as to be swingable up and down around the pivots 5a. A screed 6 is suspended on the surface. The screed 6 having the same shape is arranged at the front and back to form a pair of telescoping screeds, and is configured to be extendable to the left and right by a hydraulic cylinder.

  Further, lift cylinders 7 and 8 are attached between the upper part of the rear surface of the machine body 2 and the swing end sides of the pair of leveling arms 5, respectively. The lift cylinders 7 and 8 each have a base end of each cylinder main body rotatably attached to an upper rear surface of the machine main body 2, and tip ends of the rods 7 a and 8 a are on the swing end sides of the pair of leveling arms 5. Is pivotally attached to the.

  FIG. 5 shows a hydraulic circuit for adjusting the surface pressure of the screed 6. The surface pressure adjusting hydraulic circuit includes a main hydraulic circuit 9 that adjusts the surface pressure of the screed 6 to a constant value during the paving work, and the screed 6 sinking into the leveled asphalt mixture while the paving work is stopped. In order to suppress this, the assist pressure adjusting hydraulic circuit 10 is configured to apply assist pressure to the rods 7a and 8a of the lift cylinders 7 and 8 before and after the paving operation is stopped.

  The main hydraulic circuit 9 includes a pressure reducing valve 12 for reducing the pressure oil from the pump 11 to a constant value and an electromagnetic pilot actuated check valve 13, and is connected to the rods 7a, 8a side of the lift cylinders 7, 8. Yes. During pavement work, the pressure oil decompressed to a constant value by the pressure reducing valve 12 is supplied as back pressure to the rods 7a, 8a of the lift cylinders 7, 8. On the other hand, the assist pressure adjusting hydraulic circuit 10 includes a pressure reducing valve 14 and an electromagnetic pilot actuated check valve 15, and is connected to the rods 7 a and 8 a side of the lift cylinders 7 and 8. And before and after the paving operation is stopped, the pressure oil set to a predetermined value by the pressure reducing valve 14 is applied to the rods 7a and 8a of the lift cylinders 7 and 8 as an assist pressure.

Further, as a conventional technique related to the screed of a road paving machine, for example, the following asphalt finisher screed surface pressure adjusting device is known. In this prior art, a main hydraulic circuit including a pressure reducing valve and a solenoid valve is provided, and the main hydraulic circuit is connected to the lower part (rod side) of the screed cylinder, and the pressure is reduced to a constant value by the main hydraulic circuit during paving work. The pressure oil (40 kg / cm ² ) is supplied to the screed cylinder as a back pressure, and the surface pressure of the screed is adjusted to a constant value. The screed is configured as a telescoping screed having a pair of screeds that can expand and contract to the left and right. In addition, a hydraulic circuit for stopping is provided with a relief valve and a control valve to reduce the surface pressure of the screed to a predetermined value when paving work is stopped. Pressure oil for stopping when the pressure is reduced (70 kg / cm ² ) to a predetermined value is supplied, and the surface pressure of the screed is reduced to less than during the paving work to suppress the sinking of the screed. (For example, refer to Patent Document 1).
Japanese Utility Model Publication No. 6-67508 (pages 7 to 10, FIGS. 2, 3 and 4).

  As shown in FIG. 6, the road paving machine balances the screed weight W and the reaction force (lift) U from the asphalt mixture 16 so that the working angle α of the screed 6 with respect to the asphalt mixture 16 is maintained at a predetermined angle. Paving work is performed. In the telescoping screed capable of changing the pavement width by operating the hydraulic cylinder, the pavement width is changed even during the pavement operation. When the pave width of the screed 6 is changed, the telescoping screed does not change the screed weight W, but the reaction force U from the asphalt mixture 16 varies. That is, when the pave width increases, the reaction force U increases, and when the pave width decreases, the reaction force U decreases. For this reason, the balance between the screed weight W and the asphalt mixture reaction force U is lost, and the working angle α is changed, which affects the flatness of the pavement surface 16a and the uniformity of the pavement density.

  On the other hand, the prior art shown in FIGS. 4 and 5 is provided with a telescoping screed and supplies pressure oil decompressed to a constant value as a back pressure to the rod side of the lift cylinder during paving work. ing.

Further, in the prior art described in Patent Document 1, an extendable screed is provided, and during paving work, pressurized oil that has been depressurized to a constant value (40 Kg / cm ² ) is supplied to the screed cylinder as a back pressure, The surface pressure of the screed is adjusted to a constant value.

  However, in any of the above prior arts, since the retractable screed is provided and the back pressure of the lift cylinder is adjusted to a constant value during the paving work, when the paving width of the screed is changed, the paving The flatness of the surface and the uniformity of the pavement density may be affected.

  Therefore, even if the pave width of the screed is changed during pavement work, technical problems to be solved in order to ensure the flatness of the pavement surface and the uniformity of the pavement density arise, and the present invention solves this problem. The purpose is to solve.

  The present invention has been proposed in order to achieve the above-mentioned object, and the invention according to claim 1 is a method in which the asphalt composite material received at the front part of the machine body and conveyed to the rear part of the machine body is expanded with a screw. In addition, the screed with variable pave width by expansion and contraction is spread on the pavement surface, and the screed with variable pave width is maintained at the required working angle by the lift cylinder supplied with pressure oil of the required back pressure to the rod side. In the road paving machine, the pave width detecting means for detecting the pave width of the screed, and the back pressure so as to increase according to the increase or decrease of the pave width detected by the pave width detecting means. A back pressure variable mechanism for a screed lift cylinder in a road paving machine having a back pressure adjusting means for adjusting the pressure is provided.

  According to this configuration, the road paving machine balances the weight of the screed and the reaction force (lift) from the asphalt mixture, and the work angle of the screed with respect to the asphalt mixture is held at a predetermined angle to perform the pavement work. . When the pave width of the screed is changed during the pavement work, the telescoping screed does not change the screed weight, but the reaction force from the asphalt mixture varies. That is, when the pave width increases, the reaction force increases, and when the pave width decreases, the reaction force also decreases. For this reason, the balance between the screed weight and the asphalt composite reaction force is lost and the working angle is changed, which affects the flatness of the pavement surface and the uniformity of the pavement density. Therefore, when the pave width is increased by the back pressure adjusting means, the apparent pressure of the screed is increased by adjusting to reduce the back pressure of the lift cylinder, and when the pave width is decreased, the lift cylinder Adjust the back pressure to increase to reduce the apparent weight of the screed. As a result, even if the pave width of the screed is changed during pavement work, the screed weight and the asphalt composite reaction force are adjusted so that the work angle of the screed is maintained at a predetermined angle.

  According to a second aspect of the present invention, the back pressure adjusting means generates an assist pressure that decreases according to the increase or decrease of the pavement width detected by the pavement width detecting means, and the pressure oil of the generated assist pressure is generated. There is provided a back pressure variable mechanism for a screed lift cylinder in a road paving machine constituted by assist pressure adjusting means applied to pressure oil having the required back pressure.

  According to this configuration, an assist pressure that increases and decreases according to the increase and decrease of the pave width is generated, and the pressure oil of this assist pressure is added to the pressure oil of the required back pressure, so that it increases and decreases according to the increase and decrease of the pave width. Thus, a back pressure adjusting function for adjusting the back pressure is easily realized.

  According to a third aspect of the present invention, the assist pressure adjusting means includes a controller that calculates and outputs a control signal corresponding to the paving width, a control amount command unit that outputs a drive signal corresponding to the control signal, and a pump. There is provided a back pressure variable mechanism for a screed lift cylinder in a road paving machine comprising a proportional electromagnetic relief pressure reducing valve that adjusts the pressure oil to an assist pressure according to the drive signal.

  According to this configuration, a control signal is calculated by the controller from the pavement width detected by the pavement width detection means, and a drive signal is output from the control amount command unit by this control signal. The proportional electromagnetic relief pressure reducing valve adjusts the assist pressure pressure oil that decreases as the pavement width increases, and adjusts the assist pressure pressure oil that increases as the pave width decreases.

  The invention according to claim 1 is a paving width detecting means for detecting the paving width of the screed, and a back for adjusting the back pressure so as to increase or decrease in accordance with the increase or decrease of the paving width detected by the paving width detecting means. Since the pressure adjusting means is provided, even if the pavement width of the screed is changed during pavement work, the screed weight and the asphalt mixture reaction force are adjusted so that the working angle of the screed is maintained at a predetermined angle. Thus, there is an advantage that the flatness of the pavement surface and the uniformity of the pavement density can be ensured.

  According to a second aspect of the present invention, the back pressure adjusting means generates an assist pressure that decreases according to the increase or decrease of the pavement width detected by the pavement width detecting means, and the pressure oil of the generated assist pressure is generated. Since the assist pressure adjusting means is applied to the required back pressure pressure oil, in addition to the effect of the invention of claim 1, the increase is further reduced according to the increase or decrease of the pavement width detected by the pavement width detection means. Thus, there is an advantage that a back pressure adjusting function for adjusting the back pressure can be easily realized.

  According to a third aspect of the present invention, the assist pressure adjusting means includes a controller that calculates and outputs a control signal corresponding to the paving width, a control amount command unit that outputs a drive signal corresponding to the control signal, and a pump. In addition to the effects of the first and second aspects of the present invention, in addition to the effects of the inventions of claim 1 and 2, further according to the increase in the pavement width Thus, there is an advantage that the pressure oil of the assist pressure that decreases and the pressure oil of the assist pressure that increases according to the decrease in the pavement width can be reliably adjusted.

  Even if the pave width of the screed is changed during paving, the asphalt composite material received at the front part of the machine body and transported to the rear part of the machine body for the purpose of ensuring the flatness of the paved surface and the uniformity of the pavement density After expanding with a screw, the screed with variable pave width by stretching is spread on the pavement surface, and the screed with variable pave width performs the required work with a lift cylinder to which the pressure oil of the required back pressure is supplied to the rod side. In a road paving machine that is set so that the corner is held, a controller that calculates and outputs a control signal corresponding to the pavement width of the screed detected by the pavement width detection means, and a drive corresponding to the control signal A control amount command unit that outputs a signal, and a proportional electromagnetic relief pressure reducing valve that adjusts the pressure oil from the pump to an assist pressure according to the drive signal, and the adjusted assist The pressure oil pressure was realized by including the assist pressure adjusting means for applying the pressure oil of the desired back pressure.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a back pressure variable mechanism of a screed lift cylinder in a road paving machine. In FIG. 1, the same or equivalent components as those in FIGS. 4 and 5 are denoted by the same reference numerals as those described above, and redundant description is omitted.

  First, the configuration of the back pressure variable mechanism of the screed lift cylinder in the road paving machine according to the present embodiment will be described with reference to FIG. In this embodiment, as the screed 6, an expandable screed in which a pair of expandable screeds 6b, 6b are arranged after the main screed 6a is applied. The telescoping screed 6 is configured to be telescopic when the pair of telescoping screeds 6b, 6b are slid left and right by a hydraulic cylinder. A pair of screed width check sensors 17a, 17a are attached to both sides of the main screed 6a on the rear surface side, and a pave width detecting means 17 for detecting the pave width of the screed 6 by the pair of screed width check sensors 17a, 17a. Is configured.

  Then, the assist pressure is adjusted so as to decrease in accordance with the increase / decrease in the pavement width detected by the pavement width detecting means 17, and the pressure oil of the adjusted assist pressure is supplied from the main hydraulic circuit 9 side to the lift cylinder 7. , 8 assist pressure adjusting means 18 applied to the pressure oil of the required back pressure supplied to the rods 7a, 8a side is configured as follows.

  The assist pressure adjusting means 18 calculates and outputs a control signal corresponding to the pavement width detected by the pave width detection means 17 and outputs a drive signal corresponding to the control signal output from the controller 19. A control amount commanding unit 20 to perform, a proportional electromagnetic relief pressure reducing valve 22 for adjusting the pressure oil from the pump 21 to an assist pressure corresponding to the drive signal, and the lift cylinders 7 and 8 after the asphalt finisher 1 is stopped. An electromagnetic pilot actuated check valve 23 that locks the pressure oil supplied to the rods 7a and 8a is provided.

  That is, the assist pressure adjusting means 18 constitutes back pressure adjusting means for adjusting the back pressure of the lift cylinders 7 and 8 so as to increase or decrease in accordance with the increase or decrease of the pavement width detected by the pavement width detecting means 17. ing.

  Next, the action of the back pressure variable mechanism of the screed lift cylinder in the road paving machine configured as described above will be described with reference to FIGS. FIG. 2 is a characteristic diagram showing the relationship between the pavement width detected by the pavement width detection means 17 and the assist pressure to be adjusted. FIG. 3A shows the change of the screed pavement width during the pavement work of the asphalt finisher 1. The figure which shows an example. (B) is a figure which shows the assist pressure adjusted according to the change of the screed pavement width. (C) is a figure which shows the example of adjustment of the conventional assist pressure as a comparative example.

  As shown in FIG. 3 (a), when the pave width of the screed 6 is changed during the pavement operation, the change in the pave width is detected by the pave width detection means 17 and corresponds to the detected pave width. A control signal is output from the controller 19, and a drive signal corresponding to the control signal is output from the control amount command unit 20.

  Then, as shown in FIG. 2 and FIG. 3 (b), in the proportional electromagnetic relief pressure reducing valve 22, the assist pressure that decreases as the pave width increases is adjusted by the drive signal from the control amount command unit 20. In addition, the assist pressure that increases as the pavement width decreases is adjusted. Next, the pressure oil having the adjusted assist pressure is added to the pressure oil having the required back pressure supplied from the main hydraulic circuit 9 side to the rods 7a and 8a side of the lift cylinders 7 and 8.

  Thus, by adding the pressure oil of the assist pressure that increases and decreases according to the increase and decrease of the pave width to the required back pressure pressure oil supplied from the main hydraulic circuit 9 side, when the pave width is increased, When the back pressure of the lift cylinders 7 and 8 is adjusted to decrease, the apparent weight of the screed 6 increases, and when the pavement width decreases, the back pressure of the lift cylinders 7 and 8 is adjusted to increase. Thus, the apparent weight of the screed 6 is reduced. As a result, even if the paving width of the screed 6 is changed during the paving operation, the screed weight and the asphalt composite reaction force are adjusted so that the working angle of the screed 6 is maintained at a predetermined angle, and a desired angle is always obtained. A paved surface is constructed.

  After the asphalt finisher 1 is stopped, the check valve 13 (see FIG. 5) on the main hydraulic circuit 9 side and the check valve 23 in the assist pressure adjusting means 18 are operated, and the lift cylinders 7 and 8 on the rods 7a and 8a side. In this case, the stopping pressure oil having a predetermined pressure value higher than that during the paving work is brought into a locked state. At this time, the contraction side of the lift cylinders 7 and 8 (the side opposite to the rods 7a and 8a side) is free.

  As described above, in the back pressure variable mechanism of the screed lift cylinder in the road paving machine according to the present embodiment, when the pave width of the telescoping screed 6 is changed, it increases or decreases according to the increase or decrease of the pave width. The pressure oil of the assist pressure is reliably adjusted, and the pressure oil of the assist pressure is added to the pressure oil of the required back pressure supplied from the main hydraulic circuit 9 side. Therefore, even if the pave width of the telescoping screed 6 is changed during pavement work, the screed weight and the asphalt composite reaction force are adjusted so that the working angle of the screed 6 is maintained at a predetermined angle, The flatness of the pavement surface and the uniformity of the pavement density can be ensured.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

The structure of the back pressure variable mechanism of the lift cylinder for screeds in the road paving machine which concerns on a present Example is shown, (a) is a top view of a screed, (b) is a figure which shows a hydraulic circuit and a control block. The characteristic view which shows the relationship between the pavement width | variety and assist pressure in a present Example. (A) is a figure which shows the example of a change of the pavement width | variety at the time of pavement work. (B) is a figure which shows the adjustment example of the assist pressure according to the change of the pavement width | variety in a present Example. (C) is a figure which shows the example of a change of the conventional assist pressure as a comparative example. The side view of the conventional wheel travel type asphalt finisher. The hydraulic circuit diagram for the conventional screed surface pressure adjustment. The figure for demonstrating the working angle of a screed.

Explanation of symbols

1 Wheeled asphalt finisher (road paving machine)
DESCRIPTION OF SYMBOLS 2 Machine main body 4 Screw 6 Screed 7, 8 Lift cylinder 7a, 8a Rod 9 Main hydraulic circuit 16 Asphalt compound 16a Pavement surface 17 Pave width detection means 18 Assist pressure adjustment means 19 Controller 20 Control amount command part 21 Pump 22 Proportional electromagnetic type Relief pressure reducing valve

Claims (3)

Asphalt composite material received at the front of the machine body and conveyed to the rear of the machine body is spread with a screw, and then spread on the pavement surface with a screed with variable pave width by expansion and contraction, and the screed with variable pave width is required. In a road paving machine that is set so that the required working angle is maintained by the lift cylinder supplied with the back pressure pressure oil to the rod side,
A pave width detecting means for detecting the pave width of the screed; and a back pressure adjusting means for adjusting the back pressure so as to increase or decrease according to the increase or decrease of the pave width detected by the pave width detecting means. A variable back pressure mechanism for the screed lift cylinder in the road paving machine.   The back pressure adjusting means generates an assist pressure that increases and decreases according to the increase or decrease of the pavement width detected by the pave width detection means, and the generated pressure oil of the assist pressure is used as the pressure oil of the required back pressure. The back pressure variable mechanism for a screed lift cylinder in a road paving machine according to claim 1, wherein the back pressure variable mechanism is constituted by an assist pressure adjusting means applied to the road paving machine. The assist pressure adjusting means calculates and outputs a control signal corresponding to the pavement width, a control amount command unit that outputs a drive signal corresponding to the control signal, and pressure oil from a pump as the drive signal. 3. A variable back pressure mechanism for a screed lift cylinder in a road paving machine according to claim 2, further comprising a proportional electromagnetic relief pressure reducing valve that adjusts to a corresponding assist pressure.

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