JP2003056508A - Pilot operation hydraulic circuit for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibration of pilot valves, other than a traveling pilot valve used in traveling and reduce the operation force except for when traveling. SOLUTION: A hydraulic circuit includes a shuttle valve 32, positioned between first pilot pipes 14 and 15 variable throttle valves 33, 34 operated by pilot oil, where the pilot oil is sent front traveling pilot valve 8 via the shuttle valve 32 are provide in second pilot pipes 16 and 17 respectively. The first pilot pipes 14, 15 feed a pilot oil front the traveling pilot valve 8 to the first control valve 10, and the second pilot pipes 16, 17 feed the pilot oil from other pilot valve 9 to the second control valve 11. Thus, when the traveling pilot valve 8 is operated, traveling motor 12 revolves according to the action of the control valve 10, as well as pilot oil from the traveling pilot valve 8 is sent to variable throttle valves 33, 34 via the shuttle valve 32. Because the path of the pilot oil introduced to the second pilot pipes 16 and 17 is restricted, the back pressure of the pilot valve 9 is enhanced, and then the operation force of the lever becomes high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot operated hydraulic circuit for a construction machine such as a hydraulic excavator, and more particularly to a pilot operated hydraulic circuit for a construction machine equipped with a traveling pilot valve and a pilot valve for another actuator.

[0002]

2. Description of the Related Art Generally, a hydraulic excavator is composed of a lower traveling body that can travel in the front-rear direction, an upper revolving body that is rotatably provided on the lower traveling body, and a front working machine mounted on the upper revolving body. It is mainly configured, as a traveling motor, as an actuator for driving each part of this hydraulic excavator,
It is equipped with a swing motor, a boom cylinder, an arm cylinder, and a bucket cylinder. FIG. 2 is an explanatory view showing a conventional example of a pilot operating hydraulic circuit of a hydraulic excavator of this type. This pilot operating hydraulic circuit is a main pump 1
A pilot pump 2, a hydraulic oil tank 3, a main relief valve 4, a hydraulic oil filter 5, a pilot relief valve 6, and a lock valve 7 for shutting off pilot oil from the pilot pump 2 when the hydraulic excavator is stopped. , A traveling pilot valve 8 to which pilot oil is supplied through the lock valve 7 and other pilot valves 9, and the main pump 1
The first control valve 10 and the second control valve 11 to which pressure oil is supplied from the first control valve 10
A traveling motor 12 to which pressure oil is supplied via the second control valve 11 and another actuator 13 to which pressure oil is supplied via the second control valve 11. The pilot oil from the traveling pilot valve 8 is a set of first pilot pipes 14,
15 is guided to both ends of the first control valve 10 through the same, and similarly pilot oil from the other pilot valve 9 is also passed through the pair of second pilot pipes 16 and 17 at both ends of the second control valve 11. Guided to the department.

The traveling pilot valve 8 has an operation lever 18 rotatably provided, a set of spools 19 and 20 operated by the operation lever 18, and each spool 19,
20 has coil springs 21 and 22 for urging 20 in the neutral direction (left direction in FIG. 2), and internal pipe passages 23 and 24 communicating with the spools 19 and 20 have first pilot pipes 14 and 14, respectively.
It is connected to 15. The lever operating force of the traveling pilot valve 8 is the spring force of the coil springs 21 and 22, the pressure loss of the internal pipe lines 23 and 24, and the first pilot pipe 14,
15 pressure loss, etc.

Similarly, the pilot valve 9 for the other actuator 13 also includes the operating lever 25 and the spools 26 and 27.
And coil springs 28, 29, and each spool 26,
Internal conduits 30 and 31 from 27 are connected to the second pilot pipes 16 and 17, respectively. This pilot valve 9
The lever operating force of is also the spring force of the coil springs 28 and 29,
It is determined by the pressure loss of the internal pipe lines 30 and 31, the pressure loss of the second pilot pipes 16 and 17, and the like.

For example, when the hydraulic excavator is stopped, the lock valve 7 is held closed as shown in FIG.
The pilot oil discharged from the pilot pump 2 is blocked by the lock valve 7, and the pilot oil is not delivered even if the pilot valves 8 and 9 are operated. Next, when the lock valve 7 is manually operated in the open state during the operation of the hydraulic excavator, the pilot oil discharged from the pilot pump 2 is supplied to the traveling pilot valve 8 and the other pilot valve 9 via the lock valve 7.

In this state, when the driver of the hydraulic excavator grips the operating lever 18 of the traveling pilot valve 8 and tilts it in the forward direction (clockwise direction in FIG. 2), the spool 19 resists the spring force of the coil spring 21 and the like. The pilot oil is guided from the internal pipe line 23 to the one end (upper end of FIG. 2) of the first control valve 10 through the first pilot pipe 14, and the first control valve 10 of FIG. Pressed downward. As a result, the pressure oil is sent to the traveling motor 12 via the first control valve 10, so that the traveling motor 12 rotates in the forward direction.

On the contrary, when the operating lever 18 of the traveling pilot valve 8 is tilted backward (counterclockwise in FIG. 2), the other spool 20 is operated against the spring force of the coil spring 22 or the like. Therefore, the pilot oil from the internal pipe 24 passes through the first pilot pipe 15 and the first control valve 1
0 is guided to the other end (lower end in FIG. 2), and the first control valve 10 is pressed upward in FIG. As a result, the first
Since the pressure oil is sent to the traveling motor 12 via the control valve 10, the traveling motor 12 rotates in the reverse direction. The same applies to the operation of the other pilot valves 9.

In the above-mentioned conventional example, only one traveling motor 12 and the other actuator 13 are shown and described as actuators for driving the respective parts of the hydraulic excavator, but in reality, another traveling motor is used. In addition to the above, other actuators include a boom cylinder, an arm cylinder, a bucket cylinder, and a swing motor.

[0009]

By the way, in order to reduce the burden on the driver in this type of hydraulic excavator,
It is said that it is preferable to reduce the lever operating force of the pilot valves 8 and 9, but in the above-mentioned conventional technique, when the lever operating force of the pilot valves 8 and 9 is set to be light in this way, the traveling pilot valve 8 is operated. When the hydraulic excavator runs due to vehicle vibrations, the other actuator 1
There was a concern that the operating lever 25 of the pilot valve 9 for 3 would vibrate greatly from the neutral position. In such a case, since the pilot oil from the pilot valve 9 is sent to the second control valve 11, the actuator 13 operates erroneously against the intention of the operator of the hydraulic excavator,
It impaired operability and was dangerous.

[0010]

According to the present invention, when a construction machine that operates a traveling pilot valve is traveling, the flow of pilot oil introduced from another actuator pilot valve different from the traveling pilot valve through the second pilot pipe. We will narrow down the road temporarily. According to this structure, when the construction machine is running, the pressure loss of the second pilot pipe is increased and the back pressure of the other pilot valve for the actuator is increased, so that the lever operating force of the pilot valve can be increased. Therefore, even when the vehicle body vibration of the construction machine occurs, the other actuator pilot valve does not vibrate significantly from the neutral position. Further, since the vibrations of the pilot valves for other actuators can be suppressed during traveling as described above, the lever operating force of the pilot valves for other actuators can be lightened except when traveling.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A pilot operation hydraulic circuit for a construction machine according to the present invention comprises a traveling pilot valve and a first control valve operated by pilot oil sent from the traveling pilot valve through a first pilot pipe. And a second control valve operated by pilot oil sent from the pilot valve via another pilot pipe for another actuator via the second pilot pipe. A variable throttle valve operated by pilot oil from the traveling pilot valve is provided in the pilot pipe, and when the traveling pilot valve is operated, the flow path of pilot oil guided by the second pilot pipe is throttled by the variable throttle valve. Configured to.

According to this structure, when the traveling pilot valve is operated, the variable throttle valve is operated by the pilot oil from the traveling pilot valve, and the second throttle valve is operated by the variable throttle valve.
Since the flow path of the pilot oil guided by the pilot pipe is narrowed, the pressure loss of the second pilot pipe increases, the back pressure of the other pilot valve for the actuator increases, and the lever operating force becomes heavy. This prevents other actuator pilot valves from vibrating significantly from the neutral position even when the vehicle body vibration of the construction machine occurs.

In the above structure, it is preferable that the shuttle valve is provided with one of the pilot oils guided by the first pilot pipe and sending it to the variable throttle valve.

[0014]

EXAMPLES Examples will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a pilot operating hydraulic circuit of a hydraulic excavator according to an embodiment of the present invention. In FIG. 1, the same parts as those shown in FIG. 2 described above are designated by the same reference numerals.

As shown in FIG. 1, the pilot operating hydraulic circuit according to this embodiment is different from the above-mentioned conventional example shown in FIG. 2 in that a pair of first pilot pipes 14 and 15 are provided between these pilot pipes. A shuttle valve 32 for selecting one of the pilot oils respectively guided by 14 and 15 is provided, and pilot oil sent to the pair of second pilot pipes 16 and 17 via the shuttle valve 32 is provided. The variable throttle valves 33 and 34 to be operated are provided, and other configurations are basically the same. Variable throttle valve 3
When operated by pilot oil sent through the shuttle valve 32 when the traveling pilot valve 8 is operated, the valves 3 and 34 operate downward in FIG.
The flow paths of pilot oil guided by the second pilot pipes 16 and 17 are throttled by 3, 34.

In the pilot operated hydraulic circuit according to the present embodiment, the operator of the hydraulic excavator operates the traveling pilot valve 8
When the operating lever 18 is tilted in the forward direction (clockwise direction in FIG. 1), the spool 19 is actuated and the pilot oil is sent out from the internal pipe line 23. Therefore, this pilot oil is fed through the first pilot pipe 14 to the first pilot pipe 14. By being guided to one end of the control valve 10, the first control valve 1
0 is pressed downward in FIG. 2, and the traveling motor 12 rotates in the forward direction. At this time, since the pilot oil from the traveling pilot valve 8 is sent to the variable throttle valves 33 and 34 via the first pilot pipe 14 and the shuttle valve 32, the operation of the variable throttle valves 33 and 34 causes the second pilot pipe 16 to operate. , 17, the flow path of pilot oil guided is narrowed. As a result, the pressure loss of the second pilot pipes 16 and 17 increases and the back pressure of the pilot valve 9 increases, so that the lever operating force of the pilot valve 9 becomes heavy.

When the driver tilts the operating lever 18 of the traveling pilot valve 8 in the backward direction (counterclockwise direction in FIG. 1), the other spool 20 is actuated, so that the first control valve 10 moves to the upper position in FIG. The traveling motor 12 is rotated in the reverse direction by being pressed in the direction. Also at this time, the traveling pilot valve 8
Since the pilot oil from is sent to the variable throttle valves 33 and 34 via the first pilot pipe 15 and the shuttle valve 32, the pilot oil guided by the second pilot pipes 16 and 17 by the operation of these variable throttle valves 33 and 34. Is narrowed. As a result, the pressure loss of the second pilot pipes 16 and 17 increases and the back pressure of the pilot valve 9 increases, so that the lever operating force of the pilot valve 9 becomes heavy.

Next, when the operating lever 18 of the traveling pilot valve 8 is returned to the neutral position, pilot oil is not delivered from the traveling pilot valve 8, so that the traveling motor 12 is stopped and the variable throttle valves 33 and 34 are set to the positions shown in FIG. Returning to the initial position shown in (3), the state in which the flow passage of pilot oil guided by the second pilot pipes 16 and 17 is narrowed is released. In this state, since the pressure loss of the second pilot pipes 16 and 17 is small, the back pressure of the pilot valve 9 is low, and the pilot valve 9 can be operated with a light lever operating force.

In this embodiment having such a configuration,
Since the lever operating force of the pilot valve 9 for the other actuator 13 can be made heavy during traveling of the hydraulic excavator, even if the vehicle body vibration of the hydraulic excavator occurs, the pilot valve 9 is prevented from vibrating greatly from the neutral position. It can be prevented. In addition, since the vibration of the pilot valve 9 can be suppressed when the hydraulic excavator is running in this manner, the lever operating force of the pilot valve 9 can be made lighter than the conventional one when the hydraulic excavator is not running.

In the above embodiment as well, only one traveling motor 12 and the other actuator 13 are shown and described as actuators for driving the respective parts of the hydraulic excavator, but in reality, another traveling motor is used. In addition to the above, other actuators include a boom cylinder, an arm cylinder, a bucket cylinder, and a swing motor.

[0021]

The present invention is carried out in the form as described above, and has the following effects.

When the construction machine is running, the lever operating force of the other actuator pilot valve different from the traveling pilot valve can be made heavy, so that the vibration of the other actuator pilot valve can be suppressed even if the vehicle body vibration occurs. In addition to the above, it is possible to reduce the lever operation force of the other actuator pilot valve except when traveling. Therefore, it is possible to improve the operability when driving the construction machine and reduce the burden and fatigue on the operator of the construction machine.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a pilot operation hydraulic circuit of a construction machine according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a conventional example of a pilot operated hydraulic circuit of a construction machine.

[Explanation of symbols]

8 Travel pilot valve 9 Pilot valve 10 First control valve 11 Second control valve 12 traveling motor 13 Actuator 14,15 1st pilot pipe 16,17 Second pilot pipe 32 Shuttle valve 33,34 Variable throttle valve

Claims (2)

[Claims] 1. A traveling pilot valve, a first control valve operated by pilot oil sent from the traveling pilot valve through a first pilot pipe, a pilot valve for another actuator, and the pilot valve. In a pilot operation hydraulic circuit of a construction machine, comprising: a second control valve operated by pilot oil sent through a second pilot pipe, the second pilot pipe being operated by pilot oil from the traveling pilot valve. A variable throttle valve is provided, and when the traveling pilot valve is actuated, the flow path of the pilot oil guided by the second pilot pipe is throttled by the variable throttle valve. circuit. 2. A pilot for a construction machine according to claim 1, further comprising a shuttle valve for selecting one of pilot oils respectively guided by the first pilot pipe and sending the selected pilot oil to the variable throttle valve. Operating hydraulic circuit.