JP2014149044A - Hydraulic control system, and construction machine having the same mounted thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic control system and a construction machine having the same mounted thereon without auxiliary hydraulic control valves other than a principal hydraulic control valve such as a directional control valve, so as to have no resultant pressure loss in the piping and in the auxiliary hydraulic control valves and no reduction in efficiency while equipment layout of the construction machine is also not complicated.SOLUTION: For a boom or arm of the construction machine, a hydraulic control system includes a spool 3 for a first pump 1, and confluent spools 8 and 10 for a second pump 6, and for each of the spools, the system includes a cylinder-protective safety valve 18, in which a cylinder head side connection boat 4 of a boom cylinder for the first pump includes a pilot check valve 17 which is operational by the safety valve and an external signal while a confluent spool side for the second pump, which is connected within an interior of the control valve to a cylinder rod side connection boat 5 of an actuator for the first pump, also includes the pilot check valve.

Description

  The present invention relates to a hydraulic control system mounted on a construction machine such as a hydraulic excavator and a construction machine including the hydraulic control system, which facilitates leveling work and requires additional parts such as other hoses and hydraulic control valves. The present invention also relates to a hydraulic control system capable of easily adding a float function in consideration of safety and a construction machine equipped with the hydraulic control system.

  The float function allows the hydraulic cylinder to connect the flow paths of the rod side port and head side port of the boom cylinder to each other when the leveling work is performed uniformly using a construction machine such as a hydraulic excavator. Is a function to return the oil to the hydraulic tank.

  With this function, the boom is lowered only by its own weight, and by operating the arm of the construction machine, a constant low load is formed on each hydraulic cylinder, and the boom is moved up and down according to the shape of the ground of the corresponding work, facilitating leveling work To do. Moreover, since the working oil discharged from the hydraulic pump can be used in other work devices, energy is saved.

For example, in Patent Document 1, in order to be able to “perform leveling work while lowering the boom by its own weight without using hydraulic oil discharged from the hydraulic pump”, the “first, second hydraulic pump 1, 2 and pilot pump 3, operation lever 8, float function switch for selecting a float function, arm cylinder, swing device and travel device, boom cylinders 5 and 5a, bucket cylinder and travel device, start, stop and The main control valve 4 that controls the direction switching, the solenoid valve 7 that is switched when the float function switch is turned on, and the boom cylinders 5 and 5a that are switched when the boom is operated while the float function switch is on. Both the large chamber side and small chamber side channels are connected, and hydraulic oil is hydraulically supplied. A float valve 9 to be fed back to the tank 24, is mounted in the float valve 9, suggestions about that and a holding logic poppet which prevents the rapid descent of the boom "has been made.

  That is, it has been proposed to provide an auxiliary hydraulic control valve in addition to a main hydraulic control valve such as a direction switching valve, and further to provide a hydraulic pipe for connecting the auxiliary hydraulic control valves.

JP 2011-2092 A

  By the way, in Patent Document 1, there is a pressure loss in the piping and the auxiliary hydraulic control valve, which leads to a decrease in efficiency and a complicated equipment layout of the construction machine, which causes a great hindrance to the maintenance of the equipment. There will also be a problem with the maintenance cost.

  The present invention has been made in order to solve the above-described problem, and without providing an auxiliary hydraulic control valve other than the main hydraulic control valve such as a direction switching valve, as a result, in the piping and the auxiliary hydraulic control valve. It is an object of the present invention to provide a hydraulic control system and a construction machine equipped with the hydraulic control system, in which there is no pressure loss, the efficiency is not reduced, and the equipment layout of the construction machine is not complicated.

  In order to solve the above-mentioned problems, a hydraulic control system according to the present invention is designed to protect a boom and an arm of a construction machine from a cylinder for a spool for a first pump, a confluence spool for a second pump, and each spool. In the hydraulic control system including the safety valve, the boom cylinder head side connection boat for the first pump has a safety check valve and a pilot check valve operable by an external signal, and the boom cylinder rod side connection boat for the first pump and the control valve. The pilot check valve is also provided on the merging spool side for the second pump connected internally.

  In addition, a hydraulic control system according to the present invention includes a first pump spool, a confluence spool for a second pump, and a cylinder protection safety valve for each spool with respect to a boom and an arm of a construction machine. In the first pump, the boom cylinder head side connection boat is provided with a safety valve, the second pump boom cylinder head side connection boat is provided with a pilot check valve operable by an external signal, and the first pump boom cylinder rod side The pilot check valve is also provided on the side of the confluence spool for the second pump connected to the connection boat inside the control valve.

  Furthermore, the construction machine according to the present invention is equipped with the hydraulic control system according to the present invention.

  According to the construction machine of the present invention, in the hydraulic control system including the first pump spool, the second pump merging spool, and the cylinder protection safety valve for each spool with respect to the boom and arm of the construction machine. The first pump boom cylinder head side connection boat has a safety valve and a pilot check valve that can be operated by an external signal, and the second pump connected to the first cylinder boom cylinder rod side connection boat inside the control valve By providing the pilot check valve also on the merging spool side, there is no auxiliary hydraulic control valve other than the main hydraulic control valve such as a directional switching valve, and as a result, the pressure in the pipe and the auxiliary hydraulic control valve Equipped with a hydraulic control system with no loss, no reduction in efficiency, and no complicated equipment layout of construction machinery. It is possible to provide a construction machine.

1 is a hydraulic circuit diagram in Embodiment 1 of a hydraulic control system according to the present invention. FIG. It is a hydraulic circuit figure in Example 2 of the hydraulic control system concerning the present invention. It is a block diagram of a general construction machine, Comprising: The operation | movement of the arm at the time of excavation of leveling work is shown. It is a cross-sectional view in Example 1 of the hydraulic control system concerning the present invention.

  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 hydraulic circuit diagram in a first embodiment of a hydraulic control system according to the present invention. The hydraulic control valve according to the present invention includes a first pump 1, a second pump 6, a pilot pump (not shown), and an operation lever that outputs an operation signal in proportion to an operation amount (not shown).

  The high pressure passage 2 that is the discharge flow path of the first pump 1 is switched by the pilot signal pressure from the pilot pump by the operation of the operation lever, and at the time of switching from the first pump 1 to the boom device, the arm device, etc. A first pump boom spool 3 for controlling supplied hydraulic oil and a first pump arm merging spool 30 connected via a merging passage 33 are provided.

  The high pressure passage 7 which is the discharge flow path of the second pump 6 is switched by the pilot signal pressure from the pilot pump by the operation of the operation lever, and the boom device and the arm device are switched from the second pump 6 at the time of switching. A second pump boom merging spool 8 for controlling the hydraulic fluid supplied to the second pump is provided via a merging passage 9 and a second pump arm merging spool 10 is provided.

  A boom cylinder having a first pump boom spool 3 and a second pump boom merge spool 8, a boom cylinder head side port 4 and a boom cylinder rod side port 5 are connected, and the first pump boom spool 3 is connected to the merge passage 9. A pilot check valve 17 and a safety valve 18 are provided between the engine and the boom cylinder head side port 4. The boom cylinder head side port 4 is connected to the first pump boom spool 3 and the second pump boom merge spool 8 via the merge passage 9.

  On the other hand, the first pump arm merging spool 30 and the second pump arm merging spool 10 are connected to an arm cylinder having an arm cylinder head side port 11 and an arm cylinder rod side port 12.

  The boom cylinder rod side port 5 is connected to the first pump boom spool 3 and the second pump boom merge spool 8 via the merge passage 32. The merging passage 9 and the merging passage 32 are each connected to the tank 15 via the safety valve 18.

  Further, the merging passage 9 and the merging passage 32 are connected to the pilot check valve 17, and these are connected to the solenoid switching valve 16.

  With respect to the above configuration, the operation of the hydraulic control system according to the present invention shown in FIG. 1 will be described.

  By switching the boom cylinder head side port 4 or the first pump boom spool 3 to the opposite side via the first pump boom spool 3 from the first pump 1, the boom cylinder rod side The hydraulic oil is supplied to the port 5 from the second pump 6 through the high pressure passage 7, through the second pump boom confluence spool 8, and through the confluence passage 9 inside the control valve to the boom cylinder head side port 4. The hydraulic circuit is not supplied to the boom cylinder rod side port 5 when the second pump boom merging spool 8 is switched to the opposite side. The confluence passage 32 inside the control valve is used for discharging. The boom cylinder head side port 4 and the arm cylinder rod side port 12 are provided with a leak reduction valve 31.

  Next, the arm will be described. When the second pump 6 passes through the high pressure passage 7 and is switched to the arm cylinder head side port 11 and the opposite side via the second pump arm merging spool 10, the hydraulic oil is supplied to the arm cylinder rod side port 12. . Further, when switching from the first pump 1 through the high pressure passage 2 to the arm cylinder head side port 11 through the first pump arm confluence spool 30 and through the confluence passage 34 inside the control valve, the control valve The hydraulic oil is supplied to the arm cylinder rod side port 12 through the internal junction passage 33. Each spool is simultaneously supplied and discharged from the cylinder. In the embodiment of FIG. 1, the first pump boom spool 3 is switched on both sides, the second pump boom merging spool 8 is only supplied, and the main poppet 21 is on both sides. At the time of switching, the first pump arm merging spool 30 only discharges from the arm cylinder head side port 11.

  FIG. 2 shows a hydraulic circuit diagram in Embodiment 2 of the hydraulic control system according to the present invention. In particular, differences from the first embodiment will be described. A major difference from FIG. 1 is the position of the pilot check valve 36 connected to the merging passage 9. In the first embodiment, the pilot check valve 17 is provided closer to the boom cylinder head side port 4 than the first pump boom spool 3, whereas in the second embodiment, the pilot check valve 36 is used for the second pump. It is provided at a position farther from the boom cylinder head side port 4 than the boom junction spool 8.

With respect to the above configuration, as an operation of the hydraulic control system according to the second embodiment of the present invention, in the case of a large hydraulic excavator, the boom cylinder head side port 4 supplies the hydraulic oil from the second pump boom merging spool 8 via the piping. Supply is possible. When the first pump boom spool 3 is switched on both sides, the second pump boom joining spool 8 only discharges the boom cylinder head side port 4. When the second pump arm merging spool 10 is switched on both sides, the first pump arm merging spool 30 only discharges from the arm cylinder head side port 11.
(About pilot check valve)

  FIG. 4 shows the structure and operation of a pilot check valve 17 operable by an external signal from the solenoid switching valve 16. As an example, this is configured to be attached to the housing pocket of the same hydraulic control valve as the safety valve. An external signal (hydraulic signal) is received by the piston 19.

  When there is no external signal in the piston 19, the pressure extraction from the cylinder connection port 20 enters the back pressure chamber 22 of the main poppet 21, passes through the check valve 24 built in the sleeve 23, and further passes through the passage 25. The back pressure chamber 27 of the poppet 26 is entered. The back pressure chamber 27 is closed with a poppet 26. As a result, the main poppet 21 is pressed against the sleeve 28 by hydraulic pressure proportional to the area difference {al (area of the passage 29) −a2 (area of the cylinder connection port 20)} of the main poppet 21, and does not communicate with the tank 15. On the other hand, the hydraulic excavator has a supply of hydraulic oil (makeup function) from the tank 15 to the cylinder connection port 20 in order to avoid negative pressure in the cylinder. Therefore, the pilot check valve 17 has the same function.

  The function will be described. When the pressure in the tank 15 increases, the pressure in the back pressure chamber 22 and the cylinder connection port 20 is the same, and the pressure in the tank 15> the pressure in the cylinder connection port 20. Therefore, it is expressed by the following formula.

この式でタンク１５の圧力が高い場合には作動油はシリンダ接続ポート２０へ供給される。

In this equation, when the pressure in the tank 15 is high, the hydraulic oil is supplied to the cylinder connection port 20.

  Next, the case where there is no external signal in the piston 19 and the case where it exists will be described. As described above, when there is no external signal in the piston 19, the pressure oil from the cylinder connection port 20 enters the back pressure chamber 22 of the main poppet 21, passes through the check valve 24 built in the sleeve 23, and further passes through the passage 25. And enters the back pressure chamber 27 of the poppet 26.

  On the other hand, when the piston 19 has an external signal, the piston 19 moves to the right in the drawing by the external signal (hydraulic signal), and the pressure in the back pressure chamber 27 passes through the sleeves 28 and 29 and communicates with the tank 15. Accordingly, the pressure in the back pressure chamber 22 of the main poppet 21 is substantially equal to the pressure in the tank 15, and the main poppet 21 communicates with the open tank 15 against the area difference. Even when the pressure of the tank 15 becomes high when there is an external signal, the pressure of the tank 15 is prevented from flowing into the back pressure chamber 22 at the check valve 24, and the hydraulic oil in the tank 15 is sent to the cylinder connection port 20 as described above. Supplied.

  Further, when switching to the float function while the boom 14 is raised, the boom cylinder head side port 4 suddenly communicates with the tank 15, so the boom 14 suddenly descends and lacks safety. It will be a thing. It is known that when the boom 14 is raised, the pressure on the boom cylinder head side 4 is normally about 10 to 14 MPa (when there is no earth and sand). When the boom 14 is on the ground, the hydraulic pressure on the boom cylinder head side 4 is low. Therefore, the pressure oil from the cylinder connection port 20 enters the back pressure chamber 27 of the poppet 26, and the pressure of the external signal switched to the float function is determined by the area ratio A1 / A2 of the piston 19 and the poppet 26. It is possible to determine whether the boom 14 is on the ground by switching with an external signal of low pressure. By appropriately determining the area ratio A1 / A2, it is possible to provide a hydraulic control system capable of adding a highly safe float function.

DESCRIPTION OF SYMBOLS 1 1st pump 2 High pressure path 3 1st pump boom spool 4 Boom cylinder head side port 5 Boom cylinder rod side port 6 2nd pump 7 High pressure path 8 Second pump boom merge spool 9 Merge path 10 Second pump Arm joining spool 11 Arm cylinder head side port 12 Arm cylinder rod side port 14 Boom 15 Tank 16 Solenoid switching valve 17 Pilot check valve 18 Safety valve 19 Piston 20 Cylinder connection port 21 Main poppet 22 Back pressure chamber 23 Sleeve 24 Check valve 25 Passage 26 Poppet 27 Back pressure chambers 28, 29 Sleeve 30 First pump arm confluence spool 31 Leak reduction valve 32 Confluence passage 33 Confluence passage 34 Confluence passage 36 Pilot check valve

Claims (3)

  The boom cylinder head side for the first pump in a hydraulic control system comprising a first pump spool, a merging spool for the second pump, and a safety valve for cylinder protection for each spool against the boom and arm of the construction machine The connection boat has a safety check valve and a pilot check valve that can be operated by an external signal. The pilot check valve is also connected to the boom cylinder rod side connection boat for the first pump and the merging spool side for the second pump connected inside the control valve. A hydraulic control system comprising a valve.   The boom cylinder head side for the first pump in a hydraulic control system comprising a first pump spool, a merging spool for the second pump, and a safety valve for cylinder protection for each spool against the boom and arm of the construction machine The connection boat is equipped with a safety valve, the second pump boom cylinder head side connection boat is equipped with a pilot check valve that can be operated by an external signal, and is connected to the first pump boom cylinder rod side connection boat inside the control valve. A hydraulic control system comprising the pilot check valve on the side of a confluence spool for two pumps.   A construction machine on which the hydraulic control system according to claim 1 is mounted.

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