JPH0721649Y2 - Hydraulic motor over rotation prevention circuit for traveling of construction machinery - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for a construction machine, and more particularly to a traveling hydraulic motor overspeed prevention circuit.

[0002]

2. Description of the Related Art It is well known that a hydraulic motor is used as a traveling means of a construction machine, and an example of the hydraulic circuit is shown in FIG. A plurality of control valves 3 to 8 are connected to each of the two hydraulic pumps 1 and 2, and actuate actuators for attachments such as buckets and booms, traveling hydraulic motors, and the like. Reference numerals 9 and 10 denote left and right traveling hydraulic motors, which are connected to the control valves 5 and 8 of the plurality of control valves 3 to 8 which are arranged on the most downstream side. The pipeline 11 on the left hydraulic pump 1 side and the pipeline 12 on the right hydraulic pump 2 side are opened / closed valve 1
The hydraulic circuits of the two hydraulic pumps 1 and 2 are short-circuited when the spool of the on-off valve 13 is moved to the open position by the pilot pressure sent from the hydraulic power source 14.

[0003]

In the hydraulic circuit of the conventional construction machine described above, for example, the control valve 5 connected to the hydraulic pump 1 side is switched to rotate the traveling hydraulic motor 9 left or right. In this state, when the control valve 7 or 6 connected to the hydraulic pump 2 side is switched in order to operate an actuator other than the one for traveling, the pipe line 15 of the hydraulic power source 14 is cut off midway, and the opening / closing valve 13 is closed. The pilot pressure increases and the spool moves to the open position. Therefore, the pipeline 11 and the pipeline 12 are electrically connected, and the hydraulic circuits of the left and right hydraulic pumps 1 and 2 are short-circuited.

At this time, if the operation of the operating actuator is forcibly stopped due to some external factor, the hydraulic oil discharged from the hydraulic pump 2 does not flow to the actuator but passes through the on-off valve 13. It flows into the traveling hydraulic motor 9 on the left side. Therefore, the traveling hydraulic motor 9 is driven by the hydraulic oil discharged from both the hydraulic pumps 1 and 2, and there is a risk that it will be over-rotated and damaged.

Therefore, even if the operation of the other actuator is forcibly stopped, the operating oil is not concentrated on the traveling hydraulic motor on one side, and the problem is solved in order to prevent the traveling hydraulic motor from excessively rotating. A technical problem to be caused arises, and the present invention aims to solve this problem.

[0006]

This invention has been proposed to achieve the above-mentioned object, and a left and right traveling hydraulic motors are provided at the most downstream of a plurality of control valves respectively connected to two hydraulic pumps. In the hydraulic circuit of the construction machine, in which the control valve of each of the two hydraulic pumps is arranged and which has an opening / closing valve that short-circuits the hydraulic circuits of the two hydraulic pumps, the pilot pressures of the control valves of the left and right traveling hydraulic motors are detected. A pressure switch to detect, and a pressure switch to detect the switching operation of the control valve of another actuator, switching the solenoid valve when all of the pressure switch is turned on,
A traveling hydraulic motor overrotation prevention circuit for a construction machine, characterized in that pilot pressure is derived to the on-off valve to short-circuit the hydraulic circuits of two hydraulic pumps.

[0007]

When the control valves of the hydraulic motor for traveling are both switched in order to make the machine body of the construction machine travel straight, the pilot pressure is led to the pilot port of each control valve, and each pressure switch is turned on. In this state, if a corresponding control valve is switched in order to operate an actuator other than for traveling, this switching operation is detected and pressure switches other than for traveling are turned on. When all the pressure switches are turned on, the solenoid valve is switched to derive the pilot pressure to the open / close valve, the spool of the open / close valve moves to the open position, and the hydraulic circuits of the two hydraulic pumps are short-circuited.

Therefore, when only one traveling hydraulic motor is rotating, not all the pressure switches are turned on, and the spool of the on-off valve does not move to the open position. That is, even if the other actuator is forcibly stopped, the working oil will not be concentrated on the traveling hydraulic motor on one side.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. For convenience of explanation, the same components as those of the conventional technique will be described at the same time. 1 and 2 show a hydraulic circuit of a construction machine, in which a plurality of control valves 23 to 25 and 26 to 28 are connected to two hydraulic pumps 21 and 22, respectively. Control valves 23 and 24 on the hydraulic pump 21 side
And control valves 26, 2 on the hydraulic pump 22 side
Reference numeral 7 is for operating an actuator other than the one for traveling such as a boom or a bucket. Further, the left-side traveling hydraulic motor 29 is connected to the control valve 25 arranged on the most downstream side on the hydraulic pump 21 side, and the right-side traveling hydraulic motor 30 is connected to the control valve 28 arranged on the most downstream side on the hydraulic pump 22 side. To do.

The pipeline 31 on the hydraulic pump 21 side and the pipeline 32 on the hydraulic pump 22 side are connected by an on-off valve 33, and when pilot pressure is derived from a hydraulic source 34 through a pilot pipeline 35, The spool of the on-off valve 33 moves to the open position, and the hydraulic circuits of the hydraulic pumps 21 and 22 are short-circuited. The conduit 36 of the hydraulic pressure source 34 is the solenoid valve 3
7, the solenoid valve 37 controls the pilot pressure led to the pilot line 35. The conduit 38 branched from the conduit 36 is connected to the conduit 40 via the throttle 39.

A pressure switch 41, a pressure switch 42, and a pressure switch 43 are connected in series to the solenoid of the solenoid valve 37. The shuttle valve 44 provided in the pilot line of the control valve 25 and the pressure switch 41 are connected by the pilot line 45, and the shuttle valve 46 provided in the pilot line of the control valve 28 and the pressure switch 42 are connected. Connect with pilot line 47. Further, the conduit 48 branched from the conduit 40 in the vicinity of the throttle 39 is connected to the pressure switch 43.

In order to make the machine body of the construction machine travel straight ahead, the control valves 25 and 28 are switched by applying pilot pressures to the control valves 25 and 28, respectively, and hydraulic oil is sent from the hydraulic pumps 21 and 22 to the traveling hydraulic motors 29 and 30. To rotate. In that case, the pilot pressure of the control valve 25 is led from the shuttle valve 44 to the pilot conduit 45, and the pressure switch 41 is turned on. At the same time, the pilot pressure of the control valve 28 is led from the shuttle valve 46 to the pilot pipe line 47, and the pressure switch 42 is also turned on.

In the straight traveling state, if any of the control valves 23, 24 or 26, 27 is switched in order to operate an actuator other than the one for traveling, the pipeline 40 is cut off on the way and the hydraulic power source 34. The hydraulic oil from is discharged to the pipe line 48, and the pressure switch 43 is turned on. That is, all of the pressure switches 41, 42, 43 are turned on, an electric signal is supplied to the solenoid of the solenoid valve 37, and the spool moves from the position 37a to the position 37b. Therefore, the hydraulic oil of the pressure source 34 flows into the pilot conduit 35 from the conduit 36, the pilot pressure acts on the opening / closing valve 33, the spool moves to the open position, and the conduits 31 and 32 are electrically connected. . For this reason, the hydraulic circuits of the left and right hydraulic pumps 21 and 22 are short-circuited, the hydraulic oils flowing to the traveling hydraulic motors 29 and 30 are both maintained at the same amount, and even if other actuators are operated, the aircraft travels straight. There is no loss of sex.

Here, the case where the other actuator is operated while the machine body is traveling on one side will be further described. For example,
When the control valve 26 or 27 is switched while the control valve 25 is switched to rotate only the traveling hydraulic motor 29 on the left side, the pilot pressure is derived from the shuttle valve 44 to the pilot conduit 45, and the pressure switch is activated. When 41 is turned on, the conduit 40 is cut off midway, the hydraulic pressure in the conduit 48 is increased, and the pressure switch 43 is turned on. However, since the traveling hydraulic motor 30 on the right side is not operated, the pilot pressure is not derived to the pilot line 47 and the pressure switch 42 is turned off.

Therefore, since the solenoid valve 37 does not operate, the spool of the opening / closing valve 33 does not move to the open position, and the pipe lines 31 and 32 are not short-circuited. Therefore, even if the other actuator in operation is forcibly stopped due to some external factor, the hydraulic fluid discharged from the hydraulic pump 22 does not flow into the traveling hydraulic motor 29 on the left side. It is possible to prevent a situation in which hydraulic oil concentrates on the traveling hydraulic motor and causes excessive rotation.

The present invention can be variously modified without departing from the spirit of the invention, and it goes without saying that the invention extends to the modified version.

[0017]

As described in detail in the above-mentioned embodiment, the present invention short-circuits the hydraulic circuits of the two hydraulic pumps only when all the pressure switches are turned on. Therefore, when the aircraft is traveling on one side while operating actuators other than those for traveling, the hydraulic circuits of the left and right hydraulic pumps are not short-circuited even if the other actuators are forcibly stopped, and the hydraulic pressure for traveling on one side is It is possible to prevent hydraulic oil from concentrating on the motor and prevent the traveling hydraulic motor from excessively rotating.

[Brief description of drawings]

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

FIG. 2 is a hydraulic circuit diagram of the present invention (2).

FIG. 3 is a conventional hydraulic circuit diagram.

[Explanation of symbols]

21,22 Hydraulic pump 23,24,25,26,27,28 Control valve 29,30 Traveling hydraulic motor 33 Opening valve 37 Electromagnetic valve 41,42,43 Pressure switch

Claims (1)

[Scope of utility model registration request] 1. An opening / closing circuit in which control valves for left and right hydraulic motors for traveling are arranged at the most downstream of a plurality of control valves respectively connected to the two hydraulic pumps, and the hydraulic circuits of the two hydraulic pumps are short-circuited. In a hydraulic circuit of a construction machine equipped with a valve, a pressure switch for detecting the pilot pressure of each control valve of the left and right traveling hydraulic motors, and a pressure switch for detecting the switching operation of the control valve of another actuator are provided. A construction machine, characterized in that, when all of the pressure switches are turned on, the solenoid valve is switched to derive a pilot pressure to the on-off valve to short-circuit the hydraulic circuits of the two hydraulic pumps. Hydraulic motor over-rotation prevention circuit for traveling.