JP3248538B2 - Hydraulic circuit of construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot circuit for exerting a function of prioritizing arm turning and turning of construction machines such as hydraulic excavators and working vehicles.

[0002]

2. Description of the Related Art FIG. 2 is a side view of a hydraulic shovel.
In the drawing, 1 is a lower traveling body, 2L and 2R are left and right traveling motors, 3 is an upper revolving body, 4 is a revolving motor, 5 is a work attachment mounted on a front portion of the upper revolving body 3, 6
Is a boom of the work attachment 5, 7 is an arm, 8 is a bucket, 9 is a boom cylinder, 10 is an arm cylinder,
11 is a bucket cylinder. FIG. 3 is a conventional hydraulic circuit diagram of a hydraulic shovel. In the figure, 12 is a bottom side oil chamber of the arm cylinder 10, 13 is a rod side oil chamber, 14L and 14R are traveling switching valves for controlling traveling motors 2L and 2R (see FIG. 2), and 15 is an arm cylinder 10
A control arm pilot switching valve (hereinafter referred to as an arm switching valve), 16 is a swing pilot switching valve for controlling the swing motor 4 (hereinafter referred to as a swing switching valve), and 17 is a boom cylinder 9 (see FIG. 2) control. A pilot switching valve for a boom, 18 is a pilot switching valve for a bucket for controlling the bucket 8 (see FIG. 2), 19 is a straight traveling valve, 20L, 20L
R is a pilot on-off valve provided at the outlet of each of the center bypass oil passages 21L and 21R, 22 is a logic valve, 23 is a sequence valve, 24 is an arm merging valve, 25 is a sub-valve provided so as to be interlocked with the arm switching valve 15, 26 , 27 are first and second pumps respectively, 28 is a pilot pump which is a pilot pressure hydraulic pressure source, 29 is an oil tank, 30L, 30
R is the left and right hydraulic remote control valves, 31L and 31R are the operating levers of the hydraulic remote control valves 30L and 30R, respectively.
The symbols 符号, 、, and cheech indicate the connection of the pilot pipeline.

Next, the configuration of a conventional hydraulic circuit will be described with reference to FIGS. 2 and 3. FIG. A directional control valve for controlling various hydraulic actuators mounted on the hydraulic excavator is provided with two groups A (14L, 15, 16) and B (14R, 17, 1).
8), each of which is driven by the first pump 26 and the second pump 27. The left and right traveling switching valves 14L, 1
4R is arranged in the front row of each of the groups A and B, and the pressure oil from the first pump 26 can be supplied to the arm switching valve 15 and the swing switching valve 16 in parallel. Priority operation is performed, and when the operating pressure acting on the bottom side oil chamber 12 of the arm cylinder 10 at the time of arm pulling operation rises to a predetermined pressure, the sequence valve 23 is actuated through the arm merging valve 24 by the operation of the sequence valve 23. The pressure oil from the two pumps 27 is configured to be joined and supplied to the bottom oil chamber 12.

[0004] In a hydraulic excavator, the operation speed of arm pulling is increased so that heavy excavation can be performed. Then, when performing the arm pull operation of the operation lever 31L during the excavation work,
The arm switching valve 15 switches to the arm pulling position. First
The pressure oil from the pump 26 is supplied to the pipeline 42, the oil passage 43, the position of the straight traveling valve 19, the oil passage 44, the neutral position of the traveling switching valve 14L, the oil passages 45 and 46, the check valve 47, and the oil passage 48. ,
The oil is supplied to the bottom-side oil chamber 12 through a check valve 50, oil passages 51 and 52, an arm pulling position of the arm switching valve 15, and a pipe 53. Then, the arm cylinder 10 is extended, so that the arm pulling operation is performed. In this case, the pressure in the bottom oil chamber 12 is increased to a predetermined pressure P corresponding to the load.
(For example, 100 kg / cm 2) or more, the rising pressure is increased by the oil passages 54, 55, 56, and 5 branched from the oil passage 48.
7, the pilot port 58 of the sequence valve 23
, The sequence valve 23 switches from the position W to the position F. At the same time, part of the pilot secondary pressure acting on the pilot port 36 of the arm switching valve 15 is transferred to the line 59 communicating with the pilot port 36 and the sequence valve 23.
Through the pipe line 65, the shuttle valve 66, and the pipe line 67 to act on the pilot port 68 of the arm merging valve 24. The arm joining valve 24 switches from the shutoff oil passage position to the open oil passage position. Thus, the pressure oil from the second pump 27 is supplied to the pipe 69, the oil path 70, the neutral position of the traveling switching valve 14R, the oil paths 71, 72, the check valve 73, the oil paths 74, 75, 7
6, via the oil passage position of the arm merging valve 24, the oil passage 77, the check valve 78, and the oil passage 79, to join the oil passage 52.
Therefore, the pressurized oil from the first pump 26 and the second pump 27 is supplied to the bottom oil chamber 12 of the arm cylinder 10 in a combined manner, so that the arm pulling operation can be performed quickly to perform heavy excavation.

Next, when the operation lever 31L shown in FIG. 3 is operated to simultaneously perform the turning operation and the arm pulling operation, the pilot secondary pressure derived from the hydraulic remote control valve 30L is transmitted to the pilot port (for example, 35) of the turning switching valve 16 by the pilot port. , And acts on the pilot port 36 of the arm switching valve 15. When the swing switching valve 16 switches to the null position, the arm switching valve 1
5 switches to the arm pulling position. At the same time, a part of the pilot secondary pressure acting on the pilot port 35 of the swing switching valve 16 passes through the shuttle valve 37, the pipes 38 and 39, the logic valve 22, the pipe 40, the sub valve 25, and the pilot oil path 41. , Acting on the variable throttle portion in the re-position of the arm switching valve 15. Therefore, the return oil circuit from the rod-side oil chamber 13 of the arm cylinder 10 is narrowed by the variable throttle unit. Therefore, the return oil is regenerated and flows into the supply circuit on the bottom oil chamber 12 side through the check valve 34. When the pressure in the bottom oil chamber 12 increases,
The supply flow rate for regeneration decreases, and the turning motor 4 is driven at the same pressure as the pump pressure at that time, so that the function of giving priority to turning can be exhibited.

[0006]

In the prior art hydraulic circuit, when the arm is joined at the time of the arm pulling operation, an arm pilot secondary pressure derived from the hydraulic remote control valve is used.
It works on the pilot port of the arm merging valve. When the turning priority operation is performed during the turning and arm pulling operations, the turning pilot secondary pressure is applied to the turning priority logic valve. Both of the above pilot secondary pressure circuits were rather long and thus required a significant amount of space. In addition, since the pilot secondary pressure derived from the hydraulic remote control valve fluctuates in accordance with the operation angle of the operating lever for the working machine, the operation of arm joining or turning priority may become unstable. The present invention solves the above-mentioned problems, and allows the stable pilot primary pressure from the pilot pump to be shared and circulated to the side pilot line of the pilot switching valve for the arm. It is an object to provide a voltage circuit.

[0007]

According to the present invention, a directional control valve for controlling various hydraulic actuators mounted on a construction machine is driven by first and second pumps.
A swing priority function that enables the pump oil from the pump to be sent in parallel to each of the pilot switching valves for the arm cylinder and swing motor, and to send pressure oil prior to the swing motor during simultaneous swing and arm pull operations. In the hydraulic circuit provided, when performing simultaneous operations of turning and arm pulling, the operating pressure of the turning motor is increased by squeezing pressure oil to the bottom side oil chamber of the arm cylinder, and the operating pressure further becomes a predetermined pressure. In this case, a load check valve with a turn-priority piston that releases the throttle is provided. In addition, when the arm pull is operated alone, the throttle of the load check valve with the turning priority piston is released, and the pressure oil from the second pump is joined to the oil chamber on the bottom side of the arm cylinder.
Also, the load check valve with the turning priority piston, by the action of the pilot primary pressure from the pilot pump,
The narrowing amount is adjusted.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a hydraulic circuit diagram of the present invention. In the figure, the same reference numerals are given to components using the same components as the conventional technology. 15 'is an arm switching valve, 80 is a side pilot line (hereinafter referred to as a side pilot) which performs switching operation in conjunction with the arm switching valve 15', 16 'is a turning switching valve, and 81 is interlocking with the turning switching valve 16'. Switching side pilot, 30'L, 30'R are left and right hydraulic remote control valves, 31'L, 31'R are hydraulic remote control valves 3.
Work implement operating levers 0'L and 30'R, 82 is a load check valve with a piston, which is a load check type throttle means, and 83 is a load check valve 82 with a swing priority piston.
, 84 is a sequence valve, and 85 is a pilot port of the sequence valve 84.

Next, the configuration of the hydraulic circuit of the present invention will be described with reference to FIG. In the hydraulic circuit of the present invention, the arm switching valve 1
A load check valve 82 having a swing priority piston is provided in the main pressure operation circuit communicating with the input side port 86 of the 5 ′, and when performing simultaneous operations of the swing and the arm pull, the pilot primary pressure from the pilot pump 28 outputs the arm switching valve. 15 '
Is actuated on the piston chamber 83 of the load check valve 82 with the swing priority piston through the switching position of the side pilot 80, and the sequence is performed when the pressure of the arm bottom side circuit 87 rises to a predetermined pressure during the independent arm pulling operation. The switching operation of the valve 84 causes the pilot primary pressure to act on the pilot port 68 of the arm merging valve 24 via the switching position of the side pilot 80 of the arm switching valve 15 '.

Next, the operation of the hydraulic circuit of the present invention will be described. First, as a first case, simultaneous operations of turning and arm pulling are performed. When the work implement operating lever 31'L is operated, the swing switching valve 16 'is switched to, for example, the null position and the arm switching valve 15' is switched to the reset position. In conjunction therewith, the side pilot 81 of the swing switching valve 16 'is switched from the bypass oil passage position to the shutoff oil passage position, and the side pilot 80 of the arm switching valve 15' is switched to the switching position S. The pilot primary pressure from the pilot pump 28 is
61, 62, the switching position of the side pilot 80, the oil passages 88, 89, the throttle portion 90, and branching at the oil passage 91 (since the side pilot 81 of the swirl switching valve 16 'is at the shutoff oil passage position), It acts on the piston chamber 83 through the oil passage 92. The piston in the piston chamber 83 is operated, and the main pressure oil passage of the load check valve 82 with the turning priority piston is narrowed. The pressure in the oil passages 95 and 94 on the upstream side of the load check valve 82 with the swirling priority piston is increased, and the pressure oil from the first pump 26 branches off in the oil passage 93, and the oil passage 96, the shuttle valve 97, The oil is supplied to the turning motor 4 through the oil passage 98 and the turning switching valve 16 ′. Therefore, the operation is started from the turning at a high turning operation pressure, but when the operation pressure becomes equal to or higher than a predetermined pressure, the throttle of the load check valve 82 with the turning priority piston is not performed due to the pressure. That is, since the main pressure oil is also supplied to the bottom side oil chamber 12 of the arm cylinder 10 after the start of turning, the diagonal pulling work by the arm, the turning pressing excavation work, and the like can be performed smoothly.

Next, as a second case, an independent operation of pulling the arm is performed. Operation lever 31'L for excavation work
Is performed, the arm switching valve 15 'is switched to the arm pulling position R'. The pressure oil from the first pump 26 is supplied to the e-position of the straight travel valve 19, the neutral position of the switching valve 14L, the oil passages 45 and 46, the check valve 47, the oil passage 99,
93, 94, 95, a load check valve 82 with a turning priority piston that has not been throttled (the turning pilot valve 16 'is not operated, so the side pilot 81 is at the bypass oil passage position, and the pilot primary pressure is Does not work), oil passages 51 and 52, input port 8
6. The arm pulling position of the arm switching valve 15 ', the arm bottom side oil passage 87, and the pipeline 100, and the bottom side oil chamber 1
2 is supplied. The arm cylinder 12 extends. When the operating pressure rises to a predetermined pressure P or more, the rising pressure increases the oil passage 1 branched from the arm bottom side oil passage 87.
Through 01, it acts on the pilot port 85. The sequence valve 84 switches from the 7 'position to the f' position. The pilot primary pressure from the pilot pump 28 is
0, 61, 62, the position of the side pilot 80, the oil passages 88, 102, the position of the sequence valve 84, the oil passage 10
3. Acts on the pilot port 68 via the shuttle valve 104 and the oil passage 105. Then, the arm joining valve 24 is switched from the cutoff oil passage position to the open oil passage position, so that the pressure oil from the second pump 27 is joined to the oil passage 52 in the same manner as in the prior art. Therefore, the pressurized oil from the first pump 26 and the second pump 27 is supplied to the bottom oil chamber 12 of the arm cylinder 10 in a combined manner, so that the arm pulling operation can be performed quickly to perform heavy excavation.

[0012]

According to the first aspect of the present invention, since the stable pilot primary pressure is applied to the arm merging valve and the load check valve with the turning priority piston, the arm merging or turning priority operation is performed. Can be performed smoothly and reliably. According to the second aspect of the present invention,
In addition, the length of the arm merging valve and the turning priority pilot circuit is minimized, and the space inside the vehicle body of the hydraulic shovel can be saved.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of the present invention.

FIG. 2 is a side view of the hydraulic excavator.

FIG. 3 is a hydraulic circuit diagram of a conventional art.

[Explanation of symbols]

 Reference Signs List 4 Swing motor 10 Arm cylinder 12 Bottom side oil chamber 15, 15 'Pilot switching valve for arm 16, 16' Pilot switching valve 23, 84 Sequence valve 24 Arm merging valve 26, 27 First and second pump 28 Pilot pump 30L, 30R, 30'L, 30'R Hydraulic remote control valve 80, 81 Side pilot line 82 Load check valve with turning priority piston 83 Piston chamber

Claims (3)

(57) [Claims] 1. A directional control valve for controlling various hydraulic actuators mounted on a construction machine is driven by first and second pumps, and pressurized oil from the first pump is supplied to an arm cylinder and a swing motor. It is possible to feed oil to each pilot switching valve in parallel, and has a turning priority function that feeds pressure oil in preference to the turning motor during simultaneous operation of turning and arm pulling.
In the hydraulic circuit obtained above, when performing simultaneous operation of turning and arm pulling, the operating pressure of the turning motor is increased by squeezing pressure oil to the bottom side oil chamber of the arm cylinder, and the operating pressure is more than a predetermined pressure. When the load check
The hydraulic circuit for a construction machine characterized by having a click type throttle means. 2. When the arm pull is operated alone,
Release the narrowing of the load check type throttle means, and
Pressure from the second pump to the bottom oil chamber of the cylinder
The hydraulic circuit for a construction machine according to claim 1, wherein the oil is joined . 3. The swiveling means of the load-check type throttle means
It consists of a load check valve with a priority piston.
Load check valve with priority piston is a pilot pump
The amount of throttling is adjusted by the action of the pilot primary pressure from
The construction according to claim 1, wherein the construction is adjusted.
The hydraulic circuit of the machine.