JP2007016483A - Hydraulic control unit for loader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control unit for a loader, which can suppress enlargement even if a float mechanism and a multidirectional switching valve are integrally formed. <P>SOLUTION: A direction switching valve 11 for an arm is arranged in an arm block 20. A first pilot check valve 18 is arranged in a first block 21. A second pilot check valve 19 is arranged in a second block 22. The three blocks, that is, the arm block 20, the first block 21 and the second block 22 are juxtaposed, and the first and second blocks 21 and 22 are arranged adjacently to each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a loader hydraulic control device including a float mechanism for bringing an arm into a floating state in a front loader of a construction machine including an arm and a bucket.

  Conventionally, in a front loader, a lift arm equipped with a working machine such as a bucket is put in a floating state, that is, the oil is drained simultaneously from an extension working oil chamber and a reducing working oil chamber of a lift cylinder that moves the lift arm up and down. There is known a loader hydraulic control device that allows a lift arm to freely move up and down while grounding the working machine (see Patent Document 1).

JP 2001-1224011 A

  However, in the loader hydraulic control device described in Patent Document 1, the first valve mechanism, which is a multiple directional switching valve including a directional switching valve that controls the supply of pressure oil to each actuator, is a pilot seat of a tractor. On the other hand, a second valve mechanism, which is a float mechanism for realizing a floating state, is disposed on the front loader side. Thus, since the float mechanism and the multiple direction switching valve are configured to be provided separately, piping for connecting these separate valve mechanisms is required. Further, even if the float mechanism and the multiple direction switching valve in Patent Document 1 are integrally formed, there is a possibility that the dimensions are enlarged and the cost is greatly increased.

  In view of the above circumstances, the present invention provides a loader hydraulic control device capable of suppressing the enlargement even if the float mechanism and the multiple direction switching valve are integrally formed. With the goal.

Means and effects for solving the problems

A loader hydraulic control device according to the present invention includes an arm direction switching valve that controls supply of pressure oil to an arm cylinder, a bucket direction switching valve that controls supply of pressure oil to a bucket cylinder, and the arm cylinder. A first pilot check valve provided between the first chamber and the tank, and a second pilot check valve provided between the second chamber of the arm cylinder and the tank, and the first pilot check valve Further, the present invention relates to a hydraulic control device for a loader that brings an arm into a floating state by opening the second pilot check valve.
The loader hydraulic control apparatus according to the present invention has the following features in order to achieve the above object. That is, the loader hydraulic control device of the present invention includes the following features alone or in appropriate combination.

  In order to achieve the above object, the first feature of the loader hydraulic control apparatus according to the present invention is that an arm block in which the arm direction switching valve is arranged, the first pilot check valve, and the second pilot check valve are arranged. And a second block in which the other of the first pilot check valve and the second pilot check valve is disposed, and the arm block and the first block. Three blocks of one block and the second block are arranged side by side, and the first block and the second block are arranged adjacent to each other.

  According to this configuration, the first pilot check valve and the second pilot check valve constituting the float mechanism for realizing the floating state are integrally formed with the arm direction switching valve in the multiple direction switching valve valve. The piping for connecting can be omitted. The block where the first pilot check valve and the second pilot check valve are arranged and the block where the arm direction switching valve is arranged are configured as different blocks, and these blocks are arranged side by side. These blocks can be arranged within the projected area of the arm direction switching valve (these blocks can be arranged so as to overlap in plan view), and it is possible to prevent the size of the loader hydraulic control device from becoming enlarged. it can. Therefore, it is possible to provide a loader hydraulic control device capable of suppressing the enlargement even if the float mechanism and the multiple direction switching valve are integrally formed.

  A second feature of the loader hydraulic control device according to the present invention is that a part of the return pressure oil from the arm cylinder is diverted and supplied to the bucket cylinder when the arm direction switching valve is operated. A diversion valve that moves the bucket in a parallel state during arm operation, and a return oil passage opening / closing valve that communicates and shuts off a return oil passage through which the return pressure oil from the bucket cylinder passes when the bucket moves in parallel. , And the diversion valve is arranged in the first block.

  According to this configuration, one of the first pilot check valve and the second pilot check valve and the flow dividing valve are arranged in the same first block. Therefore, the space in which the first block is provided can be used efficiently, and even if either the first pilot check valve or the second pilot check valve and the flow dividing valve are formed integrally with the arm direction switching valve. And it can suppress that the dimension as a hydraulic control apparatus for loaders will enlarge.

  A third feature of the loader hydraulic control device according to the present invention is that a part of the return pressure oil from the arm cylinder is diverted and supplied to the bucket cylinder when the arm direction switching valve is operated. A diversion valve that moves the bucket in a parallel state during arm operation, and a return oil passage opening / closing valve that communicates and shuts off a return oil passage through which the return pressure oil from the bucket cylinder passes when the bucket moves in parallel. , And the return oil passage opening / closing valve is disposed in the first block.

  According to this configuration, one of the first pilot check valve and the second pilot check valve and the return oil passage opening / closing valve are arranged in the same first block. Therefore, the space in which the first block is provided can be efficiently used, and either the first pilot check valve or the second pilot check valve and the return oil passage opening / closing valve are formed integrally with the arm direction switching valve. Even so, the size of the loader hydraulic control device can be prevented from being enlarged.

  A fourth feature of the loader hydraulic control device according to the present invention is that a part of the return pressure oil from the arm cylinder is diverted and supplied to the bucket cylinder when the arm direction switching valve is operated. A diversion valve that moves the bucket in a parallel state during arm operation, and a return oil passage opening / closing valve that communicates and shuts off a return oil passage through which the return pressure oil from the bucket cylinder passes when the bucket moves in parallel. A variable throttle for adjusting the amount of oil diverted to the bucket cylinder among the return pressure oil from the arm cylinder, and the variable throttle is disposed in the second block.

  According to this configuration, any one of the first pilot check valve and the second pilot check valve and the variable throttle are arranged in the same second block. For this reason, the space in which the second block is provided can be used efficiently, and even if either the first pilot check valve or the second pilot check valve and the variable throttle are formed integrally with the arm direction switching valve. And it can suppress that the dimension of the hydraulic control apparatus for loaders enlarges.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. Note that the loader hydraulic control device according to the embodiment of the present invention is widely applied as a loader hydraulic control device including a float mechanism that brings an arm into a floating state in a front loader of a construction machine including an arm and a bucket. Can do.

  FIG. 1 is a hydraulic circuit diagram showing a loader hydraulic control apparatus 1 according to an embodiment of the present invention. A loader hydraulic control device 1 shown in FIG. 1 is provided in a construction machine (not shown), and is used as a hydraulic control device that controls the operation of a front loader of a construction machine including an arm and a bucket. The loader hydraulic control device 1 includes an arm direction switching valve 11, a bucket direction switching valve 12, a service direction switching valve 13, a flow dividing valve 14, a return oil passage opening / closing valve 15, a variable throttle 16, and an overload relief valve 17. The first pilot check valve 18 and the second pilot check valve 19 are provided.

  As shown in FIG. 1, the loader hydraulic control device 1 is provided with a center bypass passage 24 through which pressure oil supplied from the hydraulic pump 4 passes to the tank 5, and along the center bypass passage 24. An arm direction switching valve 11, a bucket direction switching valve 12, and a service direction switching valve 13 are provided. Each direction switching valve (11, 12, 13) is supplied with pressure oil through a parallel passage. Thus, the loader hydraulic control device 1 is also configured as a multiple direction switching valve.

  The arm direction switching valve 11 is configured as a direction switching valve that controls supply of pressure oil to an arm cylinder 2 that drives an arm (not shown). That is, when the arm direction switching valve 11 is switched from the neutral position 11b to the switching position 11a, pressure oil is supplied to the first chamber 2a of the arm cylinder 2 and the arm is raised, while the neutral position 11b is switched to the switching position 11c. By switching to, pressure oil is supplied to the second chamber 2b of the arm cylinder 2 so that the arm descends.

  The bucket direction switching valve 12 is configured as a direction switching valve that controls supply of pressure oil to a bucket cylinder 3 that drives a bucket (not shown). That is, when the bucket direction switching valve 12 is switched from the neutral position 12b to the switching position 12a, pressure oil is supplied to the second chamber 3b of the bucket cylinder 3 and the bucket operates in the scooping direction (backward tilt direction). By switching from the neutral position 12b to the switching position 12c, the pressure oil is supplied to the first chamber 3a of the bucket cylinder 3 so as to operate in the direction in which the bucket dumps (forward tilt direction).

  The diversion valve 14 diverts part of the return pressure oil from the second chamber 2b of the arm cylinder 2 as will be described later when the arm direction switching valve 11 is operated so as to be switched to the switching position 11a. Thus, the bucket is moved in a parallel state (a horizontal state with respect to the ground) during the arm ascending operation by being supplied to the first chamber 3a of the bucket cylinder 3. The return oil passage opening / closing valve 15 communicates and blocks the return oil passage 25 through which the return pressure oil from the second chamber 3b of the bucket cylinder 3 passes when the bucket moves in parallel. The diversion valve 14 and the return oil passage opening / closing valve 15 are disposed between the arm direction switching valve 11 and the bucket direction switching valve 12.

  The variable throttle 16 is configured to adjust the amount of oil diverted to the bucket cylinder 3 in the return pressure oil from the second chamber 2b of the arm cylinder 2 during the arm raising operation. The overload relief valve 17 is in communication with the first chamber 2a of the arm cylinder 2, and is configured to be able to communicate with the first chamber 2a of the arm cylinder 2 and the tank 5 in accordance with the pressure of the pressure oil. ing.

  The first pilot check valve 18 is provided in an oil passage 26 that connects the first chamber 2 a of the arm cylinder 2 and the tank 5. The first pilot check valve 18 is configured as a check valve that blocks the flow of pressure oil from the first chamber 2 a of the arm cylinder 2 to the tank 5, but is opened by operating the electromagnetic valve 28. It is supposed to be. That is, when the solenoid valve 28 is excited and opened, the check valve 30 is opened by the operation of the piston 29 into which the pilot pressure oil has been introduced, so that the one pilot chamber side of the first pilot check valve 18 is opened. The pilot pressure oil is discharged as drain and is switched to the valve open state by the pilot pressure oil acting on the other hydraulic chamber side.

  The second pilot check valve 19 is provided in the oil passage 27 that connects the second chamber 2 b of the arm cylinder 2 and the tank 5. The second pilot check valve 19 is configured as a check valve that blocks the flow of pressure oil from the second chamber 2 b of the arm cylinder 2 to the tank 5, but is opened by operating the electromagnetic valve 28. It is supposed to be. That is, when the solenoid valve 28 is excited and opened, the check valve 32 is opened by the operation of the piston 31 into which the pilot pressure oil has been introduced, and thereby the one pilot chamber side of the second pilot check valve 19 is opened. The pilot pressure oil is discharged as drain and is switched to the valve open state by the pilot pressure oil acting on the other hydraulic chamber side.

  Next, the arrangement of the above-described components in the loader hydraulic control device 1 will be described with reference to FIGS. 2 is a plan view showing the outer shape of the loader hydraulic control device 1, FIG. 3 is a side view as seen from the direction III in FIG. 2, and FIG. 4 is a side view as seen from the direction IV in FIG. It is. As shown in FIGS. 2 to 4, the loader hydraulic control device 1 includes an arm block 20, a first block 21, a second block 22, a bucket block 23, and the like. Each of these blocks (20, 21, 22, 23) is integrally formed.

  The arm block 20 is formed as a block in which the arm direction switching valve 11 is disposed. The arm block 20 is formed with an arm first port 33 which is one port communicating with the arm direction switching valve 11 (see FIG. 2). The arm first port 33 is connected to the first chamber 2a of the arm cylinder 2 (see FIG. 1). Moreover, the bucket block 23 is formed as a block in which the bucket direction switching valve 12 is disposed.

  The first block 21 is disposed between the arm block 20 and the bucket block 23. In the first block 21, a first pilot check valve 18, a branching valve 14, and a return oil passage opening / closing valve 15 are arranged. In the first block 21, the diversion valve 14 and the return oil passage opening / closing valve 15 are orthogonal to the plane on which the arm direction switching valve 11 and the bucket direction switching valve 12 are located, as shown in FIG. It is arranged on a plane.

  The second block 22 is disposed between the arm block 20 and the bucket block 23 (between the arm direction switching valve 11 and the bucket direction switching valve 12). A first block 21 is disposed between the second block 22 and the arm direction switching valve 11 (between the second block 22 and the arm block 20). That is, the second block 22 is adjacent to the first block 21 on the side opposite to the arm block 20. The second block 22 includes a second pilot check valve 19, a variable throttle 16, and an overload relief valve 17. Further, the second block 22 is formed with an arm second port 34 which is the other port communicating with the arm direction switching valve 11 (see FIG. 2). The arm second port 34 is connected to the second chamber 2b of the arm cylinder 2 (see FIG. 1).

  As described above, in the loader hydraulic control device 1, the three blocks of the arm block 20, the first block 21, and the second block 22 are arranged side by side, and the first block 21 and the second block 22 are adjacent to each other. Are arranged to be.

  Next, the operation of the loader hydraulic control device 1 having the above-described configuration will be described with reference to FIG. As described above, the arm is raised by switching the arm direction switching valve 11 to the switching position 11a, and the arm is lowered by switching to the switching position 11c. When the bucket direction switching valve 12 is switched to the switching position 12a, the bucket operates in the scooping direction, and when the bucket direction switching valve 12 is switched to the switching position 12c, the bucket operates in the dumping direction.

  In addition, the loader hydraulic control device 1 performs a parallel movement function of moving the bucket while keeping the bucket in a parallel state during the arm raising operation. When the arm direction switching valve 11 is switched to the switching position 11a, the pressure oil from the hydraulic pump 4 is supplied to the first chamber 2a of the arm cylinder 2 and the arm starts to rise. At this time, the return pressure oil from the second chamber 2 b of the arm cylinder 2 flows to the diversion valve 14. The return pressure oil that has flowed to the diversion valve 14 acts on two hydraulic chambers provided on both sides of the diversion valve 14 so that the position of the diversion valve 14 is switched. Thereby, a part of the return pressure oil from the second chamber 2b of the arm cylinder 2 is divided and supplied to the first chamber 3a of the bucket cylinder 3 through the oil passage 35, and the remaining pressure oil is used for the arm. It flows from the center bypass passage 24 to the tank 5 via the direction switching valve 11. Note that the amount of oil divided into the bucket cylinder 3 out of the return pressure oil from the arm cylinder 2 is appropriately adjusted by the variable throttle 16.

  Then, the pressure oil that is diverted by the diversion valve 14 and supplied to the bucket cylinder 3 and the pressure oil that flows to the arm direction switching valve 11 are provided on both sides of the return oil passage opening / closing valve 15 as pilot pressure oil, respectively. Acts on the hydraulic chamber. As a result, the return oil passage opening / closing valve 15 is switched from the state of blocking the return oil passage 25 to the state of communication, and the return pressure oil from the second chamber 3b of the bucket cylinder 3 passes through the return oil passage 25. It flows to the tank 5 through the arm direction switching valve 11. Thus, the bucket moves in the direction of dumping with the arm ascending operation, and the bucket parallel movement function is achieved.

  In addition, the loader hydraulic control device 1 also fulfills a floating function for bringing the arm into a floating state. When the arm is in a floating state, for example, in a state where the bucket is grounded, first, the electromagnetic valve 28 is excited and switched. Thereby, the piston 29 and the piston 31 are operated by the pressure oil from the pilot pump, and the check valve 30 and the check valve 32 are opened. As a result, the pilot pressure oil on one spring chamber side of the first pilot check valve 18 and the second pilot check valve 19 is discharged as a drain and switched so as to be opened by the pilot pressure oil acting on the other hydraulic chamber side. Will be. As described above, when the first pilot check valve 18 and the second pilot check valve 19 are opened, a floating state is realized in which the arm freely moves up and down when the bucket is grounded. Become.

  As described above, according to the loader hydraulic control device 1 according to the present embodiment, the first pilot check valve 18 and the second pilot check valve 19 constituting the float mechanism for realizing the floating state are switched in multiple directions. The arm direction switching valve 11 in the valve valve is integrally formed, and piping for connecting them can be omitted. The blocks (21, 22) in which the first pilot check valve 18 and the second pilot check valve 19 are arranged and the block 20 in which the arm direction switching valve 11 is arranged are configured as different blocks. Since the blocks (20, 21, 22) are arranged side by side, these blocks (20, 21, 22) can be arranged within the projected area of the arm direction switching valve 11 (so that these blocks overlap in plan view). It is possible to prevent the size of the loader hydraulic control device from being enlarged. Therefore, it is possible to provide a loader hydraulic control device capable of suppressing the enlargement even if the float mechanism and the multiple direction switching valve are integrally formed.

  Further, according to the loader hydraulic control device 1, the first pilot check valve 18 and the flow dividing valve 14 are arranged in the same first block 21. For this reason, the space in which the first block 21 is provided can be utilized efficiently, and even if the first pilot check valve 18 and the diversion valve 14 are formed integrally with the arm direction switching valve 11, the loader hydraulic pressure It can suppress that the dimension as a control apparatus enlarges.

  Further, according to the loader hydraulic control device 1, the first pilot check valve 18 and the return oil passage opening / closing valve 15 are arranged in the same first block 21. For this reason, the space in which the first block 21 is provided can be utilized efficiently, and even if the first pilot check valve 18 and the return oil passage opening / closing valve 15 are formed integrally with the arm direction switching valve 11, It can suppress that the dimension of the hydraulic control apparatus for loaders enlarges.

  Further, according to the loader hydraulic control device 1, the second pilot check valve 19 and the variable throttle 16 are arranged in the same second block 22. Therefore, the space in which the second block 22 is provided can be used efficiently, and even if the second pilot check valve 19 and the variable throttle 16 are formed integrally with the arm direction switching valve 11, the loader hydraulic pressure It can suppress that the dimension of a control apparatus enlarges.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, the second pilot check valve may be arranged in the first block, and the first pilot check valve may be arranged in the second block. Further, the arm block, the first block, and the second block may not be arranged in the order as described in the embodiment, and these three blocks are arranged side by side and the first block and the second block are arranged. What is necessary is just to be arrange | positioned so that 2 blocks may adjoin.

1 is a hydraulic circuit diagram showing a loader hydraulic control device according to an embodiment of the present invention. It is a top view which shows the external shape of the hydraulic control apparatus for loaders shown in FIG. It is the side view seen from the III direction of FIG. It is the side view seen from the IV direction of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Loader hydraulic controller 2 Arm cylinder 2a Arm cylinder first chamber 2b Arm cylinder second chamber 3 Bucket cylinder 5 Tank 11 Arm direction switching valve 12 Bucket direction switching valve 18 First pilot check valve 19 Second pilot Check valve 20 Arm block 21 First block 22 Second block

Claims (4)

An arm direction switching valve that controls the supply of pressure oil to the arm cylinder;
A bucket directional control valve that controls the supply of pressure oil to the bucket cylinder;
A first pilot check valve provided between the first chamber of the arm cylinder and the tank;
A second pilot check valve provided between the second chamber of the arm cylinder and the tank;
With
A loader hydraulic control device that opens an arm of the first pilot check valve and the second pilot check valve to bring the arm into a floating state;
An arm block in which the arm direction switching valve is disposed, a first block in which any one of the first pilot check valve and the second pilot check valve is disposed, the first pilot check valve, and the A second block in which the other of the second pilot check valves is disposed,
The arm block, the first block, and the second block are arranged side by side, and the first block and the second block are arranged adjacent to each other. Hydraulic control device for loader. A diversion valve that moves a bucket in a parallel state during an arm operation by diverting a part of the return pressure oil from the arm cylinder when the arm direction switching valve is operated and supplying it to the bucket cylinder; ,
A return oil passage opening / closing valve for communicating and blocking a return oil passage through which return pressure oil from the bucket cylinder passes during parallel movement of the bucket;
With
2. The loader hydraulic control device according to claim 1, wherein the diversion valve is disposed in the first block. A diversion valve that moves a bucket in a parallel state during an arm operation by diverting a part of the return pressure oil from the arm cylinder when the arm direction switching valve is operated and supplying it to the bucket cylinder; ,
A return oil passage opening / closing valve for communicating and blocking a return oil passage through which return pressure oil from the bucket cylinder passes during parallel movement of the bucket;
With
2. The loader hydraulic control device according to claim 1, wherein the return oil passage opening / closing valve is disposed in the first block. A diversion valve that moves a bucket in a parallel state during an arm operation by diverting a part of the return pressure oil from the arm cylinder when the arm direction switching valve is operated and supplying it to the bucket cylinder; ,
A return oil passage opening / closing valve for communicating and blocking a return oil passage through which return pressure oil from the bucket cylinder passes during parallel movement of the bucket;
A variable throttle that adjusts the amount of oil diverted to the bucket cylinder among the return pressure oil from the arm cylinder;
With
2. The loader hydraulic control device according to claim 1, wherein the variable throttle is disposed in the second block.

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