JP4223034B2 - Hydraulic circuit of compaction device - Google Patents

Description

  The present invention relates to a hydraulic circuit of a compaction device, and more particularly to a hydraulic circuit of a compaction device in a road paving machine that can improve the rotation accuracy of a tamper motor group and a vibrator motor group in a low rotational range. Is.

  An example of a hydraulic circuit of a conventional compaction device is shown in FIG. In the figure, a discharge line 2 from a hydraulic source 1 is branched at a part of a diversion valve 3 into a tamper side line 4 and a vibrator side line 5. The tamper side conduit 4 is communicated with the tank 7 via tamper motor groups 6a-6c, and the vibrator side conduit 5 is communicated with the tank 7 via vibrator motor groups 8a-8d. A tamper-side flow rate control valve 10 is provided in a tamper-side bypass conduit 9 leading from the upstream side of the tamper motor groups 6a to 6c in the tamper-side conduit 4 to the tank 7, and a tamper-side bleed-off circuit is configured. In addition, a vibrator-side flow control valve 12 is provided in a vibrator-side bypass conduit 11 leading from the upstream side of the vibrator motor groups 8a to 8d in the vibrator-side conduit 5 to the tank 7, and a vibrator-side bleed-off circuit is configured. Yes.

  Of the hydraulic oil supplied from the hydraulic power source 1 to the tamper motor groups 6a to 6c, a flow rate other than the amount of hydraulic oil necessary for the rotation of the tamper motor groups 6a to 6c is bypassed to the tank 7 by the tamper side flow control valve 10. Thus, the rotational speeds of the tamper motor groups 6a to 6c are adjusted. Similarly, among the hydraulic oil supplied from the hydraulic power source 1 to the vibrator motor groups 8a to 8d, the flow rate other than the hydraulic oil amount necessary for the rotation of the vibrator motor groups 8a to 8d is the vibrator side flow control valve 12. Therefore, the rotation speed of the vibrator motor groups 8a to 8d is adjusted by bypassing the tank 7.

  Further, as a conventional technique related to the hydraulic circuit of the compacting device, for example, the following hydraulic control device is known. In this prior art, a center open type first and second switching valves are provided in series on a neutral passage that connects a variable discharge pump with a regulator and a tank, and a parallel passage branched from the neutral passage, First and second switching valves are connected in parallel to the variable discharge pump, and actuators having different working load pressures are connected to the first and second switching valves, respectively. In addition, a pressure compensation valve is provided on the parallel passage, a second switching valve downstream of the pressure compensation valve is provided with a meter-in throttle at one switching position, and the pressure between the upstream and downstream of the meter-in throttle It acts on the pressure compensation valve. For the variable discharge pump with the regulator, a throttle is provided upstream of the tank, and the pressure upstream of the throttle is applied to the regulator to control the discharge amount. As described above, this conventional hydraulic control device is configured as a proportional control valve type by a large number of components.

When the actuators are operated by simultaneously switching the first and second switching valves, the hydraulic oil supplied to the actuator connected to the second switching valve passes through the meter-in throttle, and the meter-in throttle The pressure between the upstream and downstream of the pressure acts on the pressure compensation valve. The pressure compensation valve changes the opening according to the pressure between the upstream and downstream of the meter-in throttle, and flows into the second switching valve so that the differential pressure between the upstream and downstream of the meter-in throttle is always constant. Control the amount. As a result, the actuator connected to the second switching valve is not supplied with an unnecessarily high flow rate, and a plurality of actuators with different load pressures can be used simultaneously and optimally with a variable discharge pump with one regulator. (See, for example, Patent Document 1).
JP-A-6-117407 (pages 3 to 4, FIG. 1).

  In the prior art using the bleed-off circuit of FIG. 2, surplus hydraulic oil is simply bypassed to the tank at the inlet side of the tamper motor group or vibrator motor group as an actuator, so that good rotation accuracy is obtained. This is not sufficient, and the rotation accuracy is deteriorated particularly in the low rotation region of the tamper motor group or vibrator motor group in which the supply flow rate to the tamper motor group or vibrator motor group is small and the bypass flow rate is large.

  In the prior art described in Patent Document 1, one of the variable discharge pump with a regulator, the center open type first and second switching valves provided in series on the neutral passage, and one of the second switching valves. A proportional meter having a number of components such as a pressure compensation valve which is provided on a meter-in throttle provided at the switching position and a parallel passage branched from the neutral passage and on which the pressure between the upstream and downstream of the meter-in throttle acts. It is configured as a control valve type. For this reason, the cost is high.

  Therefore, there is a technical problem to be solved in order to improve the rotation accuracy in the low rotation range of the tamper motor group and the vibrator motor group, and to reduce the cost, and the present invention solves this problem. With the goal.

  The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 divides a discharge pipe of a hydraulic power source into a tamper side pipe and a vibrator side pipe, and the tamper side pipe is provided. Is connected to the tank via a tamper side flow control valve and a tamper motor group constituting a tamper side meter-in circuit, and the vibrator side pipe is communicated to the tank via a vibrator side flow control valve and a vibrator motor group constituting a vibrator side meter-in circuit. Further, between the tamper motor upstream position immediately before the tamper motor group in the tamper side pipe line and the vibrator motor upstream position immediately before the vibrator motor group in the vibrator side pipe line, the hydraulic pressure in the tamper motor upstream position and the vibrator motor upstream position Connect a shuttle valve to select the higher hydraulic pressure at And the hydraulic pressure at the upstream position of the tamper motor and the hydraulic pressure at the upstream position of the vibrator motor are adjusted by adjusting the pressure of the hydraulic fluid discharged from the hydraulic pressure source based on the higher hydraulic pressure selected by the shuttle valve. There is provided a hydraulic circuit of a compacting device having a load fluctuation relief valve that is controlled so as to always have the higher hydraulic pressure.

  According to this configuration, the tamper and the vibrator are attached to the screed in the road paving machine and normally operate simultaneously when leveling the asphalt mixture. Therefore, the tamper motor group for driving the tamper and the vibrator motor group for driving the vibrator also usually rotate simultaneously. During the rotation of the tamper motor group and the vibrator motor group, the tamper motor flow rate control valve and the vibrator side flow rate control valve respectively act on the tamper motor group and the vibrator motor group regardless of load fluctuations of the tamper motor group and the vibrator motor group. The flow rate of each hydraulic oil is maintained at a predetermined amount, and the hydraulic pressure of each hydraulic oil is suppressed to a predetermined pressure, so that the tamper motor group and the vibrator motor group rotate with high accuracy, particularly in a low rotation range.

  Furthermore, the pressure of the hydraulic fluid from the hydraulic source is adjusted by the load fluctuation relief valve based on the higher hydraulic pressure selected by the shuttle valve, and the hydraulic pressure at the upstream position of the tamper motor and the hydraulic pressure at the upstream position of the vibrator motor are constantly It is controlled so as to be the higher hydraulic pressure among the upstream positions.

  According to the first aspect of the present invention, the discharge line of the hydraulic power source is branched into a tamper side line and a vibrator side line, and the tamper side line includes a tamper side flow control valve and a tamper motor group constituting a tamper side meter-in circuit. Since the vibrator side pipe line communicates with the tank via the vibrator side flow control valve and the vibrator motor group constituting the vibrator side meter-in circuit, the load fluctuations of the tamper motor group and the vibrator motor group can be reduced. Regardless of this, the flow rate of each hydraulic oil to the tamper motor group and vibrator motor group is maintained at a predetermined amount, and the hydraulic pressure of each hydraulic oil is suppressed to a predetermined pressure, so that the tamper motor group and vibrator motor group are lower than the bleed-off circuit. The rotation accuracy in the rotation range can be improved. The tamper-side pipe line is provided with a tamper-side flow rate control valve, and the vibrator-side pipe line is provided with a vibrator-side flow rate control valve. There is an advantage that costs can be reduced.

  Further, between the tamper motor upstream position just before the tamper motor group in the tamper side pipe line and the vibrator motor upstream position just before the vibrator motor group in the vibrator side pipe line, the hydraulic pressure at the tamper motor upstream position and the hydraulic pressure at the vibrator motor upstream position are A shuttle valve that selects a higher hydraulic pressure of the hydraulic pressure is connected, and operates based on the higher hydraulic pressure selected by the shuttle valve, and adjusts the pressure of hydraulic fluid discharged from the hydraulic pressure source to Since the load fluctuation relief valve for controlling the hydraulic pressure at the upstream position of the tamper motor and the hydraulic pressure at the upstream position of the vibrator motor so as not to always become the higher hydraulic pressure is provided, the hydraulic pressure at the upstream position of the tamper motor and the hydraulic pressure at the upstream position of the vibrator motor are Always at the higher hydraulic pressure of the two upstream positions By being controlled so that there is the advantage that it is possible to improve the rotational accuracy at low speed range Tanpamota group and a vibrator motor group further.

  For the purpose of improving the rotation accuracy of the tamper motor group and vibrator motor group in the low rotation range and reducing the cost, the discharge line of the hydraulic power source is branched into the tamper side pipe and the vibrator side pipe, and the tamper The side pipe line communicates with the tank via a tamper side flow control valve and a tamper motor group constituting a tamper side meter-in circuit, and the vibrator side line passes through a vibrator side flow control valve and a vibrator motor group constituting a vibrator side meter-in circuit. Further, between the tamper motor upstream position immediately before the tamper motor group in the tamper side pipe line and the vibrator motor upstream position immediately before the vibrator motor group in the vibrator side pipe line, the hydraulic pressure in the tamper motor upstream position and the vibrator are communicated with the tank. The higher of the oil pressure at the upstream position of the motor A shuttle valve for selecting a hydraulic pressure is connected and operated based on the higher hydraulic pressure selected by the shuttle valve, and the hydraulic pressure at the upstream position of the tamper motor is adjusted by adjusting the pressure of the hydraulic oil discharged from the hydraulic source. This is realized by providing a load fluctuation relief valve that controls the hydraulic pressure at the upstream position of the vibrator motor to always be the higher hydraulic pressure.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a hydraulic circuit diagram of a compaction device. First, the configuration of the hydraulic circuit of the compaction device according to the present embodiment will be described with reference to FIG.

  A discharge line 14 of a constant capacity type hydraulic pump (hereinafter simply referred to as a hydraulic pump) 13 as a hydraulic source is communicated with the tank 7 via a normally open electromagnetic switching valve 15, and then the discharge line 14 passes through a relief valve 16. After that, it communicates with the tank 7. The normally open electromagnetic switching valve 15 returns the discharge oil of the hydraulic pump 13 to the tank 7 when the apparatus is not in operation, and sets the hydraulic pump 13 to a no-load state. The relief valve 16 sets the discharge oil of the hydraulic pump 13 to a required value that is appropriately larger than the oil pressure and the oil amount corresponding to the speed adjustment range by a meter-in circuit described later.

  On the downstream side of the relief valve 16, the discharge pipe 14 is branched into a tamper-side pipe 17 and a vibrator-side pipe 18. The tamper side pipe line 17 communicates with the tank 7 via a tamper side flow control valve 19 and tamper motor groups 6a to 6c constituting a tamper side meter-in circuit, and the vibrator side pipe line 18 is a vibrator side constituting a vibrator side meter-in circuit. The tank 7 is communicated with the flow rate control valve 20 and the vibrator motor groups 8a to 8d. Both the tamper side flow control valve 19 and the vibrator side flow control valve 20 are provided with check valves.

  Between the tamper motor upstream position 17a immediately before the tamper motor group 6a to 6c in the tamper side pipe line 17 and the vibrator motor upstream position 18a immediately before the vibrator motor group 8a to 8d in the vibrator side pipe line 18 at the tamper motor upstream position 17a. A shuttle valve 21 is connected to select a higher one of the hydraulic pressure and the hydraulic pressure at the vibrator motor upstream position 18a.

  Further, the discharge pipe 14 on the downstream side of the relief valve 16 is communicated with the tank 7 via a load fluctuation relief valve 22. The load fluctuation relief valve 22 is operated based on the higher hydraulic pressure selected by the shuttle valve 21, and the hydraulic fluid flowing through the discharge pipe 14 is relieved to the tank 7, and the hydraulic pressure at the tamper motor upstream position 17 a and Control is performed so that the hydraulic pressure at the vibrator motor upstream position 18a is always the higher hydraulic pressure.

  Next, the operation of the hydraulic circuit of the compacting device configured as described above will be described. The tamper and the vibrator are attached to the screed in the road paving machine and normally operate simultaneously when the asphalt mixture is laid, and act to consolidate and compact the asphalt mixture. Therefore, the tamper motor groups 6a to 6c for driving tamper and the vibrator motor groups 8a to 8d for driving the vibrator also normally rotate at the same time.

  During the rotation operation of the tamper motor groups 6a to 6c and the vibrator motor groups 8a to 8d, the shuttle valve 21 selects the higher one of the hydraulic pressure at the tamper motor upstream position 17a and the hydraulic pressure at the vibrator motor upstream position 18a. Then, the load fluctuation relief valve 22 is operated based on the selected higher hydraulic pressure, the hydraulic oil flowing through the discharge pipe 14 is relieved to the tank 7, and the hydraulic pressure at the tamper motor upstream position 17a and the vibrator motor upstream position 18a are The oil pressure is always controlled to be the higher one of the two upstream positions 17a, 18a.

  Further, the tamper motor group 6a and the vibrator side flow control valve 20 and the tamper motor group 6a to 6c and the vibrator motor groups 8a to 8d are not affected by the load fluctuations of the tamper motor group 6a to 6c and the vibrator motor group 8a to 8d. To 6c and vibrator motor groups 8a to 8d are maintained at a predetermined amount. As a result, the tamper motor groups 6a to 6c and the vibrator motor groups 8a to 8d rotate with high precision, particularly in a low rotation range, and a required consolidation action is obtained.

  As described above, in the hydraulic circuit of the compacting device according to the present embodiment, the rotational accuracy of the tamper motor groups 6a to 6c and the vibrator motor groups 8a to 8d can be improved in comparison with the bleed-off circuit. it can.

  The tamper motor groups 6a to 6c and the tamper motor upstream position 17a and the vibrator motor upstream position 18a are controlled so that the hydraulic pressure at the higher position of the two upstream positions 17a and 18a is not always higher. The rotation accuracy in the low rotation range of the vibrator motor groups 8a to 8d can be further improved.

  In this way, by being configured with a small number of components, it is possible to reduce the cost as compared with the proportional control valve type.

  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 circuit diagram of the hydraulic circuit of the compaction apparatus which concerns on the Example of this invention. The circuit diagram of the hydraulic circuit of the conventional compaction apparatus.

Explanation of symbols

6a-6c Tamper motor group 7 Tank 8a-8d Vibrator motor group 13 Hydraulic pump (hydraulic power source)
14 Discharge pipe 17 Tamper side pipe 17a Tamper motor upstream position 18 Vibrator side pipe 18a Vibrator motor upstream position 19 Tamper side flow control valve 20 Vibrator side flow control valve 21 Shuttle valve 22 Load fluctuation relief valve

Claims (1)

The discharge line of the hydraulic power source is branched into a tamper side line and a vibrator side line, and the tamper side line communicates with the tank via a tamper side flow control valve and a tamper motor group constituting a tamper side meter-in circuit. The side pipe line communicates with the tank via the vibrator side flow rate control valve and the vibrator motor group constituting the vibrator side meter-in circuit,
Further, between the tamper motor upstream position immediately before the tamper motor group in the tamper side pipe line and the vibrator motor upstream position immediately before the vibrator motor group in the vibrator side pipe line, the hydraulic pressure at the tamper motor upstream position and the hydraulic pressure at the vibrator motor upstream position are A shuttle valve that selects a higher hydraulic pressure of the hydraulic pressure is connected, and operates based on the higher hydraulic pressure selected by the shuttle valve, and adjusts the pressure of hydraulic fluid discharged from the hydraulic pressure source to A hydraulic circuit for a compacting device, comprising a load fluctuation relief valve that controls the hydraulic pressure at the upstream position of the tamper motor and the hydraulic pressure at the upstream position of the vibrator motor so as to always become the higher hydraulic pressure.

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