JPS64450Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a swing brake device for a hydraulic excavator such as a excavator or shovel.

In hydraulic excavators with high swing speeds, in order to prevent shock when the swing stops, a brake valve is inserted into the hydraulic circuit of the swing motor to absorb the shock when the swing stops. Because the shock was absorbed by a brake valve that fixed the braking force at a constant level, it was difficult to rotate the excavator, as when the bucket of an excavator is loaded with earth and sand, and the bucket is located far from the center of rotation of the rotating base. If the moment of inertia acting on the base is large,
If the moment of inertia acting on the swing base is small, such as when the braking force is insufficient and the swing drifts when stopped, the bucket is empty, and the bucket is close to the center of the swing, the braking force There was a problem that the shock was too strong and the shock when stopping was large.

The present invention was developed in view of the above circumstances, and includes a detector that detects the pressure generated in the boom cylinder that swings the boom, and a detector that is inserted into the circuit of the swing motor and uses the pressure detected by the detector to detect the pressure generated in the boom cylinder that swings the boom. It is an object of the present invention to provide a swing brake device for a hydraulic excavator that can always smoothly stop swinging by including a brake valve whose control force is changed.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a hydraulic excavator, in which a boom 3, an arm 4, and a bucket 5 are sequentially pivotally connected to a rotating base 2 rotatably provided on a vehicle body 1.
is swung by the expansion and contraction of a boom cylinder 6 whose both ends are pivoted to the swing base 2 and boom 3, and the arm 4 is swung by the expansion and contraction of an arm cylinder 7 whose both ends are pivoted to the boom 3 and arm 4. is a bucket cylinder 8 whose both ends are pivoted to the arm 4 and bucket 5.
The bucket 5 of the excavator is loaded with soil or empty, and whether the bucket 5 is located far from or close to the center of rotation of the swing base 2. Accordingly, the magnitude of the moment of inertia acting on the swing base 2 changes. In other words, the moment of inertia acting on the swing base 2 is equal to the moment of inertia acting on the boom 3 acting on the boom cylinder 6.
It is approximately proportional to the magnitude of the downward moment, and therefore, the rod-side oil chamber of the boom cylinder 6, on which the downward moment of the boom 3 acts, is in proportion to the moment of inertia acting on the swing base 2. Approximately proportional pressures will be generated.

FIG. 2 shows the hydraulic circuit of a hydraulic excavator, and the pressure oil discharged from the pump 10 is transferred to each switching valve 11, 12,
13 and 14, the switching valve 11 operates the bucket cylinder 8, the switching valve 12 operates the arm cylinder 7, the switching valve 13 operates the boom cylinder 6, and the switching valve 14 operates the swing motor 9. be done. A brake valve 15 is inserted into a pipe connecting the switching valve 14 and the swing motor 9, and the brake valve 15 cross-connects both pipes of the swing motor 9 via relief valves 16 and 17. This prevents a shock when the rotation stops by releasing the pressure oil in the pipe to the low pressure pipe. The relief valves 16 and 17 are equipped with pilots that change the relief pressure, and this pilot line 18 is connected to the rod-side oil chamber of the boom cylinder 6, which is a detector. Therefore, when the pressure in the rod side oil chamber of the boom cylinder 6 increases, the relief pressure of the relief valves 16 and 17 also increases, and when the pressure in the rod side oil chamber of the boom cylinder 6 decreases, the relief pressure of the relief valves 16 and 17 increases. Relief pressure also decreases.

With the above configuration, when the swing is stopped, that is, when the switching valve 14 is returned from the operating position to the neutral position, the swing motor 9 tries to rotate due to inertia, so the return side pipe of the swing motor 9 becomes high pressure.
When the pressure in the return pipe reaches the relief pressure of the relief valves 16 and 17, the relief valve 16 or 17 opens, the pressure oil in the return pipe flows to the opposite pipe, and the swing motor 9 returns. It rotates until the pressure in the side pipe becomes equal to or lower than the relief pressure of the relief valves 16 and 17.

Since the relief pressure of the relief valves 16 and 17 rises and falls in proportion to the pressure in the rod-side oil chamber of the boom cylinder 6, the braking force of the brake valve 15 is almost proportional to the moment of inertia acting on the swing base 2. The rotation base 2 always stops at a substantially constant braking distance.

As described above, according to the present invention, the braking force of the swing brake, which was always constant in the past, changes depending on the pressure generated in the boom cylinder, so the swing will stop at a nearly constant braking distance regardless of the working state of the excavator. In addition, a swing brake device is provided which is particularly effective in a hydraulic excavator that performs work by selectively attaching a heavy breaker to the tip of the arm.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a side view of a hydraulic excavator, and FIG. 2 is a hydraulic circuit diagram. 2...Swivel base, 3...Boom, 4...Arm, 5...Bucket, 6...Boom cylinder, 7
...Arm cylinder, 8...Bucket cylinder,
9...Swivel motor, 15...Brake valve, 18...
...Pilot conduit.

Claims (1)

[Scope of utility model registration request] A swing brake device for a hydraulic excavator in which a boom and an arm are sequentially attached to a swing base includes a detector that detects the pressure generated in a boom cylinder that swings the boom, and a swing motor that is inserted into the circuit of the swing motor. A swing brake device for a hydraulic excavator, comprising a brake valve whose braking force changes according to detected pressure.