JP6096002B2 - Hydraulic control device and construction machine equipped with the hydraulic control device - Google Patents

Description

  The present invention relates to a hydraulic control device mounted on a construction machine having a hydraulic actuator that expands and contracts in the vertical direction, such as a hydraulic dozer, and to a construction machine equipped with the hydraulic control device, and in particular, a hydraulic control device that improves posture holding accuracy when stopped And the construction machine on which it is mounted.

  A conventional technique will be described with reference to FIGS.

  FIG. 3 is a cross-sectional view of a directional control valve in a conventional hydraulic control apparatus for construction machinery.

  These switching valves 1 are connected to a hydraulic pump (not shown) via a pump line (not shown) and tank ports 20a and 20b are connected to a tank (not shown) via a tank line.

  The switching valve 1 basically includes a common pressure oil supply passage 12a that receives the pressure oil from the pump in the valve body 10, a switching spool 13 that is slidably fitted in the valve body 10, and this switching valve. An intermediate chamber 14 that receives supply of pressure oil from the pressure oil supply passage 12a by the movement of the spool 13, cylinder ports 15a and 15b, and these cylinder ports 15a and 15b are provided between the pressure oil supply passage 12a. A passage 16 for supplying pressure oil from the intermediate chamber 14 to the cylinder port 15a or 15b, a check valve 17 provided on the passage 16, and the pressure spool at the cylinder ports 15a, 15b are tanked by the movement of the switching spool 13. Auxiliary ports 18a, 18b that discharge to the ports 20a, 20b, a pressure compensation passage 19 that connects these auxiliary ports 18a, 18b in communication, and a front The tank ports 20a and 20b and the tank passage 21 located outside the auxiliary ports 18a and 18b, and the flow rate adjusting means 25 provided between the tank passage 21 and the pressure compensation passage 19 are built in. Become.

  The switching spool 13 is provided with notches 22a and 22b for connecting the pressure oil supply passage 12a to the intermediate chamber 14 as the switching spool 13 moves, and auxiliary ports 18a and 18b, respectively, as cylinder ports 15a and 15b or Notches 23a, 23b and 24a, 24b for communicating with the tank ports 20a, 20b are provided. Here, the notches 22a and 22b are for pump discharge flow control for controlling the pump discharge amount, the notches 23a and 23b are for actuator return oil control for controlling the return pressure oil amount from the actuator 38, and the notches 24a and 24b are The pressure compensation function for controlling the amount of pressure oil that returns the pressure oil in the pressure compensation passage 19 to the tank ports 20a and 20b is provided.

  The flow rate adjusting means 25 includes a spool 26 and a spring 27. The spool 26 is slidably fitted into a spool hole 28 formed in the valve body 10, and one end thereof is surrounded by a cover 29. One end of the internal passage 41 provided in the spool 26 is connected to the back chamber 34 provided in the valve body 10 via the check valve 31 and the passage 32, and the other end opens to the front chamber 33.

  The flow rate adjusting means 25 having the above-described configuration is configured so that the shoulder 26a of the spool 26 engages with the spool hole 28 as the spool 26 moves upward against the spring force of the spring 27, and the opening A Is gradually reduced by being regulated by a notch 36 provided in the spool 26. On the other hand, the front chamber 33 is connected to the intermediate chamber 14 through the passage 35, and the spring 27 is accommodated in the front chamber 33 to elastically hold the other end of the spool 26. Further, the back chamber 34 is connected to a back chamber 34 ′ (not shown) of the other switching valve 1 via a communication passage 37 (not shown). The passage 35 has a function as a pressure detection of the intermediate chamber 14, and the check valve 31 has a function of detecting the highest pressure among the pressures detected by the passage 35.

  In the switching valve 1 having such a configuration, the opening degree of the notches 22a and 22b is adjusted by the movement amount of the switching spool 13, and the discharge flow rate of the hydraulic pump is determined. Therefore, if the area ratio of the actuator 38 is known, the return oil amount from the actuator 38 corresponding to the operation amount of the switching spool 13 is inevitably known. For this reason, the notches 24a and 24b can be set to a throttle characteristic that can obtain an arbitrary compensation pressure according to the amount of movement of the switching spool 13 when all of the return oil amount from the actuator 38 passes. Further, in the flow rate adjusting means 25, when the notch 36 moves in the closing direction (upward in FIG. 3), the spool hole 28, the notch 36 and the opening degree can be made zero.

  The hydraulic control apparatus configured as described above operates as follows. For example, when the switching spool 13 of the switching valve 1 is operated in the right direction in FIG. 3, the hydraulic oil corresponding to the notch 22 a is discharged from the hydraulic pump and guided to the intermediate chamber 14 by the movement amount. After that, the air is supplied from the check valve 17 and the passage 16 to the actuator 38 through the cylinder port 15a. On the other hand, the return pressure oil from the actuator 38 reaches the pressure compensation passage 19 through the cylinder port 15b and the notch 23b.

  By the way, when the actuator 38 is neutral, it returns to both ends of the cylinder and is fixed without moving the oil and the discharged oil, thereby maintaining the posture of the actuator.

  Subsequently, FIG. 4 shows a dozer which is a ground surface modification machine having a conventional movably attached tool. A side view of an embodiment of a ground surface modification machine 60 with a tool 62 movably attached is disclosed. In this embodiment, the ground modification machine is a crawler tractor and the implement is an elongated blade used to level the ground. The ground surface modification machine 60 includes a frame 64, a chassis 66 coupled to the frame 64, and a prime mover 68 such as an internal combustion engine. The motor | power_engine 68 is connected so that power may be transmitted to the endless crawler track 70 of the chassis 66 by a normal well-known method. The prime mover rotates the endless crawler track 70 and advances the ground surface modification machine 60 above the ground below. The isolated first and second push arms 72 and 74 are pivotally connected to the tool 62 and the frame 64 at their opposite ends, respectively, by a conventional method such as a pivot shaft, and the tool 62 is connected to the frame 64. Connect to be pivotable. The push arms are approximately the same length and hold the tool laterally at the front end of the ground surface modification machine 60 as viewed from the cab 65.

  Tilt jack means 76, including extensible and isolated fluid actuated first and second tilt jacks 78, 80 (preferably but not limited to hydraulic cylinders), are used to move the tool 62 from the base position to the first and first positions relative to the frame 64. Provided to tilt in two directions. The base position is where the tool is in a substantially horizontal position when the ground modification machine 60 is supported on a substantially flat horizontal surface. The rod end 82 of the first inclined jack 78 is pivotally attached to the tool 62 by a normal method such as a U-link and a pivot pin. Similarly, the rod end 84 of the second inclined jack 80 is pivotally attached to the tool 62 by a normal method such as a U-link and a pivot pin. The head end portion 86 of the first inclined jack 78 is pivotally attached to the first push arm 72 by a usual method such as a U link and a pivot pin. Similarly, the head end 88 of the second inclined jack 80 is pivotally attached to the second push arm 74 by a normal method such as a U-link and a pivot pin. The connection between the rod and the head end can be reversed. When the rod end portions 82, 84 of either the first or second inclined jacks 78, 80 are extended or contracted with respect to the head end portions 86, 88, the tool 62 is inclined. In this connection, the ground leveling can be controlled by controlling the tilt angle θ. The inclination angle θ viewed from the cab 65 appears by lowering the right or left corner of the tool 62 relatively.

  Separate fluid-actuated first and second lift jacks 90, 92 are provided for moving the tool up relative to the frame 64. The fluid operated lift jack is preferably a hydraulically operated fluid operated lift cylinder of known construction. The first lift jack 90 has a first end 94 pivotably connected to the frame 64, and the second lift jack 92 has a first end 96 pivotally connected to the frame 64. The first lift jack 90 has a second end 98 that is pivotally connected to the tool 62, and the second lift jack 92 has a second end 100 that is pivotally connected to the tool 62. Such a pivotable connection to the frame 64 and the tool 62 is made by a normal method such as U-link and pivot pin arrangement. The second ends 98, 100 can move to extend relative to the respective first ends 94, 96. The upward movement of the tool 62 relative to the frame 64 (around the pivot connection of the first and second push arms 72, 74) corresponds to this extension movement.

JP 2008-202704 A

  By the way, when pressure is generated in the pressure oil supply passage 12a even in the neutral state, the pressure oil passes through a gap formed between the valve body 10 and the switching spool 13, and the pressure oil supply passage 12a and the passage 16 And pass through the cylinder ports 15a and 15b to reach the actuator 38. As a result, the posture of the actuator is not maintained. For this reason, the problem that the actuator 38 cannot be fixed at the time of stopping has arisen.

  Accordingly, the present invention has been made to solve the above-described problems, and when the posture of the actuator is neutral, the hydraulic pressure that can maintain the posture of the actuator when pressure is generated in the pressure oil supply passage. An object is to provide a control device and a construction machine equipped with the control device.

  In order to solve the above-described problems, a hydraulic control device for a construction machine according to the present invention includes a valve body including a plurality of oil chambers including a pressure oil supply passage, a cylinder port, and a tank port, and a slide in the valve body. Pressure oil that is inserted in a fluid-tight manner and supplied from the pressure oil supply passage is supplied to the actuator via the cylinder port, and return oil from the actuator is discharged from the tank port to the tank line. In a direction control valve having a switching spool for switching the supply and discharge of oil, an intermediate chamber provided between the pressure oil supply passage and the cylinder port, and a check valve provided between the intermediate chamber and the cylinder port In the case of a directional control valve in which the hydraulic cylinder that is the actuator is a direction in which the expansion and contraction direction of the rod is disposed below the horizontal direction with respect to the vertical direction There are, when the switching spool of the sites are arranged near neutral, and providing a notch in a portion connecting the cylinder port side to reduce the intermediate chamber and the hydraulic cylinder of the switching spool.

  In order to solve the above problems, a construction machine according to the present invention is equipped with the hydraulic control device.

  According to the hydraulic control device of the present invention, a valve body having a plurality of oil chambers including a pressure oil supply passage, a cylinder port, and a tank port, and a slidably liquid-tightly inserted into the valve body, A switching spool that supplies the pressure oil supplied from the pressure oil supply passage to the actuator via the cylinder port and switches the supply and discharge of the oil so that the return oil from the actuator is discharged from the tank port to the tank line; In the directional control valve having an intermediate chamber provided between the pressure oil supply passage and the cylinder port and a check valve provided between the intermediate chamber and the cylinder port, a hydraulic cylinder as an actuator is connected to the rod. In the case of a directional control valve in which the expansion / contraction direction is a direction disposed below the horizontal direction with respect to the vertical direction, When the actuator is in a neutral position by providing a notch in the portion connecting the intermediate chamber of the switching spool and the cylinder port on the side that contracts the hydraulic cylinder, In this case, the posture of the actuator can be maintained.

It is a cross-sectional view of the direction control valve in the Example of the hydraulic control apparatus which concerns on this invention. It is an enlarged view of the shoulder part of the direction control valve in the Example of the hydraulic control apparatus which concerns on this invention. It is a cross-sectional view of a conventional directional control valve. It is a block diagram of the conventional dozer.

  The configuration of the hydraulic control system according to the present invention will be described through two embodiments with reference to FIGS.

  FIG. 1 shows a cross-sectional view of a directional control valve in a hydraulic control device for a construction machine according to the present invention.

  The switching valve 1 shown in FIG. 1 is connected to a hydraulic pump (not shown) via a pump line (not shown), and tank ports 20a and 20b are connected to a tank (not shown) via a tank line.

  The switching valve 1 basically includes a common pressure oil supply passage 12a that receives pressure oil from a pump in the valve body 10, and a switching spool 13 that is slidably and liquid-tightly inserted into the valve body 10. And an intermediate chamber 14 that receives supply of pressure oil from the pressure oil supply passage 12a by the movement of the switching spool 13, cylinder ports 15a and 15b, cylinder ports 15a and 15b, and the pressure oil supply passage 12a. A passage 16 for supplying pressure oil from the intermediate chamber 14 to the cylinder port 15a or 15b, a check valve 17 provided on the passage 16, and the cylinder spools 15a, 15b Auxiliary ports 18a and 18b for discharging pressure oil to the tank ports 20a and 20b, and a pressure compensating passage 1 for connecting these auxiliary ports 18a and 18b in communication And tank ports 20a, 20b and a tank passage 21 located outside the auxiliary ports 18a, 18b, and a flow rate adjusting means 25 provided between the tank passage 21 and the pressure compensation passage 19, respectively. Consisting of

  The switching spool 13 is provided with notches 22a and 22b for connecting the pressure oil supply passage 12a to the intermediate chamber 14 as the switching spool 13 moves, and auxiliary ports 18a and 18b, respectively, as cylinder ports 15a and 15b or Notches 23a, 23b and 24a, 24b for communicating with the tank ports 20a, 20b are provided. Here, the notches 22a and 22b are for pump discharge flow control for controlling the pump discharge amount, the notches 23a and 23b are for actuator return oil control for controlling the return pressure oil amount from the actuator 38, and the notches 24a and 24b are The pressure compensation function for controlling the amount of pressure oil that returns the pressure oil in the pressure compensation passage 19 to the tank ports 20a and 20b is provided.

  Here, a notch 50a is formed in the shoulder portion 50, which is a portion connecting the intermediate chamber 14 of the switching spool 13 and the cylinder port 15a on the side where the actuator 38 is contracted. FIG. 2 shows a detailed view thereof.

  The hydraulic control apparatus configured as described above operates as follows.

The switching spool 13 transitions from a state in which pressure oil flows from the cylinder port 15a to a state in which pressure oil flows from the cylinder port 15b in response to a signal from the pressure oil signal port. In the state of the neutral these two neither, side pressure oil pressure oil supply passage 12a passes through the gap between the valve body 10 and the switching spool 13, intermediate chamber 14, through the notch 50a, to reduce the piston rod 39 of the actuator 38 Acting on the cylinder port 15a. A heavy object such as a soil discharge plate is provided at the tip of the piston rod 39, and the notch 50a is an opening through which the actuator 38 maintains its posture.

As described above, by providing the partial notch 50a connecting the side of the cylinder port 15a to reduce the piston rod 39 of the intermediate chamber 14 and the actuator 38 of the switching valve 1 of the switching spool 13, pressure oil supply switching spool 13 is in a neutral state Even when pressure oil is present in the passage 12a, the posture holding accuracy of the actuator 38 can be improved.

  In the above embodiment, the hydraulic control valve portion for the dozer of the hydraulic control device for construction machinery has been described. However, the present invention is not limited to the hydraulic control valve portion for the dozer of the hydraulic control device for construction machinery, and the rod of the hydraulic cylinder faces downward. The present invention can also be applied to holding the cylinder posture with the attached mechanism.

1 switching valve 10 valve body 12a pressure oil supply passage 12b tank port 13 switching spool 14 intermediate chamber 15a cylinder port 15b cylinder port 16 passage 17 check valve 18a, 18b auxiliary port 19 pressure compensation passage 20a, 20b tank port 21 tank passage 22a , 22b, 23a, 23b, 24a, 24b Notch 25 Flow rate adjusting means 26 Spool 26a Shoulder 27 Spring 28 Spool hole 29 Cover 31 Check valve 32 Passage 33 Front chamber 34 Back chamber 35 Passage 36 Notch 37 Communication passage 38 Actuator 39 Piston Rod 41 Frame 50 Shoulder 50a Notch 60 Ground surface modification machine 62 Tool 64 Frame 65 Driver's cab 66 Chassis 68 Engine 70 Endless crawler belt 72 First push arm 74 Second push arm 76 Tilt jack means 78 First tilt Yakki 80 second tilt jack 82 rod end 84 the rod end 88 head end 90 first lift jack 92 second lift jack 94 first end portion 96 first end 98 second end 100 second end

Claims (2)

Pressure oil supply passage, a valve body having a plurality of oil chambers containing cylinder port and the tank port, said slidable fluid-tight manner is inserted into the valve body, the hydraulic fluid supplied from the hydraulic fluid supply passage supplies to the actuator via the cylinder port, the return oil from the actuator, a switching spool for switching the oil supply and discharge to discharge from the tank port to the tank line, the pressure oil supplied by the movement of the switching spool an intermediate chamber for receiving a supply pressure from passage, said a passage for supplying pressurized oil to the cylinder port from the intermediate chamber is provided between the cylinder port and said pressurized oil supply passage, the cylinder port and the intermediate chamber wherein a check valve which is provided on the passage, in the direction control valve having a hydraulic cylinder whose rod is the actuator between Direction der the stretching direction is disposed on the lower side facing the horizontal direction with respect to the vertical direction is, when the neutral vicinity shoulder of switching spool to block the passage disposed in the cylinder port side of said passageway A hydraulic control device for a construction machine, characterized in that a notch is provided in a shoulder portion connecting an intermediate chamber of a switching spool and a cylinder port on a contraction side rather than a side on which a hydraulic cylinder is extended .   A construction machine equipped with the hydraulic control device according to claim 1.

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