JPH075283Y2 - Warm-up circuit of hydraulic working machine - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to a hydraulic work machine such as a hydraulic excavator or a hydraulic crane, and particularly for a short period of warm-up operation for raising the temperature of hydraulic oil during cold weather. The present invention relates to a warm-up circuit that can be carried out.

(Prior Art) Conventionally, as a hydraulic circuit for operating an actuator by a variable displacement hydraulic pump, for example, as shown in FIG. 4, a pilot switching valve provided in a discharge side conduit 2'of a variable displacement hydraulic pump 1 '. An actuator such as a hydraulic cylinder 4'is connected to 3 ', and the actuator is operated by operating the remote control valve 10 to switch the pilot switching valve 3', and the throttle valve 5'is provided after the pilot switching valve 3 '.
And a branch line 6'branched from the preceding stage of the throttle valve 5'is connected to the pump controller 7 ', and the variable displacement hydraulic pump 1'when the pilot switching valve 3'is in the neutral position. The discharge oil from the tank is directly returned to the tank 16 'through the pilot switching valve 3'and is throttled by the throttle valve 5', and the hydraulic pressure generated in the preceding stage of the throttle valve 5'is pump-controlled via the branch pipe line 6 '. It is designed to reduce the amount of oil discharged from the variable displacement hydraulic pump 1'to the device 7 '.

(Problems to be solved by the invention) Conventionally, when used in winter or in cold regions, the temperature of the hydraulic fluid of the hydraulic actuator has also dropped, so the viscosity of the hydraulic fluid is high and the response of the operation is high. It is known that there is a problem such as a bad condition and a large pressure loss, and in order to solve this problem, warm-up operation is generally performed at the beginning of the work.

However, as shown in FIG. 4, in the hydraulic circuit of the operating machine, when the pilot switching valve 3'is in the neutral position, the hydraulic pressure generated in the preceding stage of the throttle valve 5'is supplied to the pump controller via the branch line 6 '. Since the amount of oil discharged from the variable displacement hydraulic pump 1'is reduced by introducing the variable displacement hydraulic pump 1'to 7 ', when the warming operation of the working machine is performed with the pilot switching valve 3'in neutral, the variable displacement hydraulic pump 1' Since the amount of oil discharged from the throttle valve 5'is controlled to the minimum amount by the pump controller 7 ', the amount of oil passing through the throttle valve 5'is small and the amount of heat generated by the throttle valve 5'is also small, which requires a long time for warm-up operation. As a result, the work efficiency is reduced.

On the other hand, as a means for shortening the warm-up time, the remote control valve is operated to switch the pilot switching valve 3'to the operating position,
Extend the actuator 4'to the stroke end and operate the relief valve 17 'in the overload state to operate the relief valve
It is possible to raise the temperature of the hydraulic oil by the amount of heat generated from 17 ', but in this case, the warm-up time will be longer than that when warm-up is performed with the pilot switching valve 3'in the neutral position. Although it can be shortened, the operator must continue to operate the remote control valve 10 'during warm-up operation in a cold driver's cab, which is an extremely painful task for the operator, and the pilot conduit 11a , 11b
Since the pilot system oil was still confined, we could not expect an increase in the oil temperature, and we were still unable to improve the response satisfactorily.

(Means for Solving Problems) The present invention relates to a hydraulic actuator in which the discharge oil from the variable displacement hydraulic pump 1 is guided to an actuator 4 via a pilot switching valve 3 and the actuator 4 is operated. A throttle valve 5 is provided at a stage subsequent to the center bypass of the pilot switching valve 3, and a branch pipe line 6 branched from a stage before the throttle valve 5 is connected to a pump controller 7 of the variable displacement hydraulic pump 1.
And a switch valve 13a, 13b, 13c for selectively connecting or disconnecting the pipeline to the branch pipeline 6 are provided, and when the branch pipeline 6 and the pump controller 7 are blocked, a variable capacity Pump 1
Or from the pilot pump 8 to the pilot lines 11a, 11b
By supplying the discharge oil to, it is possible to easily perform a warm-up operation in a short time to raise the temperature of the hydraulic oil prior to work in cold weather.

(Embodiment) The present invention will be described below with reference to an embodiment shown in the drawings.

In FIG. 1, reference numeral 1 is a variable displacement hydraulic pump, and a pilot switching valve 3 is connected to a discharge side pipe line 2 of the pump 1.

Although only one pilot switching valve 3 is illustrated in this embodiment, a plurality of switching valves may be connected in parallel.

An actuator such as a hydraulic cylinder 4 or a hydraulic motor is connected to the pilot switching valve 3.

Reference numeral 5 is a throttle valve provided in the latter stage of the center bypass of the pilot switching valve 3, and a branch pipe line 6 is branched and connected to the front stage of the valve 5, and the branch pipe line 6 is of the variable capacity type. It is connected to a pump controller 7 that controls the discharge amount of the hydraulic pump 1.

A pilot pump 8 is connected to a remote control valve 10 via a pipe 9, and the remote control valve 10 is connected to pilot ports 12a and 12b of the pilot switching valve 3 via pilot pipes 11a and 11b, respectively. And remote control valve 10
Is operated to supply pilot pressure to either of the left and right pilot ports 12a, 12b of the pilot switching valve 3, and the pilot switching valve 3 is switched to expand or contract or rotate the actuator such as the hydraulic cylinder 4. ing.

Reference numeral 13a is an electromagnetic switching valve, which branches from the branch line 6 and a line 9 connecting the pilot pump 8 to a remote control valve, and is connected to both pilot lines 11 via check valves 14a and 14b.
It is interposed across the pipeline 15a connected to a and 11b.

Therefore, by switching the electromagnetic switching valve 13a, the branch pipe 6 branched from the preceding stage of the throttle valve 5 is connected to the pump controller 7 and the pipe 15a is shut off.
Check valve 1 for pilot pump 8 communicating with line 15a
The pilot lines 11a and 11b are connected to each other via 4a and 14b, and the branch line 6 and the pump controller 7 can be selectively switched to a disconnected state.

Although this electromagnetic switching valve 13a has the same effect even if it is replaced with a manual switching valve, it is desirable that the manual switching valve is a non-reset type that is maintained at that position once it is operated once.

16 is a hydraulic oil tank, 17 is a relief valve, 18 is a remote control valve 10
It is the operation lever of.

FIGS. 2 and 3 show other embodiments of the present invention, respectively, which are basically the same as the embodiment shown in FIG. I omit the explanation, and explain only the difference.

In the embodiment shown in FIG. 2, the solenoid operated directional control valve 13b is branched from the branch line 6 and the discharge side line 2 of the variable displacement hydraulic pump 1 to both pilot lines via check valves 14a and 14b. It is provided so as to straddle a pipeline 15b connected to 11a and 11b.

Therefore, by switching the electromagnetic switching valve 13b, the branch pipe line 6 branched from the preceding stage of the throttle valve 5 is connected to the pump controller 7 and the pipe line 15b is shut off.
The variable displacement hydraulic pump 1 is connected to the check valves 14a, 14
Both of the pilot lines 11a and 11b are connected via b, and the branch line 6 can be selectively switched to a state in which the branch line 6 is disconnected from the pump controller 7.

Further, in the embodiment shown in FIG. 3, the electromagnetic switching valve 13c is interposed in the branch pipe line 6, and by switching the switching valve 13c, the branch pipe line 6 and the pump controller 7 are connected. It is adapted to be selectively switched and connected to both pilot lines 11a and 11b via 15c and check valves 14a and 14b.

Next, the operation of this invention will be described.

However, the operation of the embodiment shown in FIGS. 1 to 3 is substantially the same and will be described together.

First, in the warm-up operation, the electromagnetic switching valves 13a, 13b, 13c are switched from the states shown in FIGS. 1 to 3 to connect the branch pipe line 6 connecting the front stage of the throttle valve 5 and the pump controller 7. Shut off.

The pilot pump 8 is used in the embodiment shown in FIG.
And both pilot lines 11a, 11b are connected via check valves 14a, 14b.

In the embodiment shown in FIG. 2, the variable displacement hydraulic pump 1 and both pilot lines 11a and 11b are connected to the check valves, 14a and 1b.
Connect via 4b.

Furthermore, in the embodiment shown in FIG. 3, the branch line 6 and both pilot lines 11a, 11b are connected via check valves 14a, 14b.

At this time, in any of the embodiments, the pump controller 7 is connected to the tank 16 side of the rear stage of the throttle valve 5.

Therefore, in this state, the pump controller 7 controls the discharge amount of the variable displacement hydraulic pump 1 to a preset discharge amount (maximum discharge amount) regardless of whether or not the pilot switching valve 3 is operated.

Therefore, if the variable displacement hydraulic pump 1 is driven in this state, a large amount of discharge oil (neutral) is supplied to the throttle valve 5 without operating the pilot switching valve 3 and the throttle resistance also increases. Due to the large amount of heat generated by the throttle, the oil temperature of the hydraulic oil rises in a short time.
The discharge oil from the pilot pump 8 or the variable displacement hydraulic pump 1 also circulates in b. (Warm-up operation is completed.) Next, when performing normal work, the electromagnetic switching valve 13a is switched to the state shown in FIG. 1 to FIG. In this state, the pilot pressure introduced from the preceding stage of the throttle valve 5 to the pump controller 7 via the branch pipe line 6 acts on the pump controller 7.

Therefore, when the pilot switching valve 3 is not operated, the oil discharged from the variable displacement hydraulic pump 1 passes through the center bypass of the pilot switching valve 3, passes through the throttle valve 5, and the hydraulic oil tank 16
At this time, the hydraulic pressure generated in the oil passage by the throttle valve 5 is led to the pump controller 7 via the branch pipe passage 6,
The pump controller 7 acts to reduce the discharge amount of the variable displacement pump 1 by this pilot pressure.

Further, when the pilot switching valve 3 is operated to shut off the center bypass of the valve 3, the discharge oil does not flow to the throttle valve 5, so that the pump controller is substantially the same as in the warm-up operation described above. Since the pilot pressure is not supplied to the pump 7, the pump controller 7 sets the preset discharge amount (maximum discharge amount).
Then, the discharge amount of the variable displacement hydraulic pump 1 is controlled.

(Effects of the Invention) According to the present invention, a switching valve is provided in a branch pipe which is branched from the preceding stage of the throttle valve and connected to the pump controller, and the switching valve is used for warm-up operation and normal operation. The warm-up operation can be completed in a short time only by switching operation, which can improve the work efficiency, and the operator's working environment is improved because the operator does not need to perform any special operation in the cold cab. it can.

In addition, since the oil is circulated to the pilot system such as the pilot line during the warm-up operation, it is possible to eliminate the temperature rise delay due to the oil confinement in the pilot system. And so on.

[Brief description of drawings]

FIG. 1 is a warm-up circuit showing an embodiment of the present invention. 2 and 3 are warm-up circuits showing other embodiments of the present invention.
FIG. 4 is a hydraulic circuit diagram of a conventional hydraulic working machine. 1: Variable displacement hydraulic pump 3: Pilot switching valve 4: Actuator (hydraulic cylinder) 5: Throttle valve, 6: Branch line 7: Pump controller, 8: Pilot pump 10: Remote control valve 11a, 11b: Pilot line 13a, 13b, 13c: Switching valve (solenoid switching valve)

Claims (1)

[Scope of utility model registration request] 1. A hydraulic working machine in which discharge oil from a variable displacement hydraulic pump (1) is guided to an actuator (4) through a pilot switching valve (3) and the actuator (4) is operated. Pilot switching valve (3)
A branch pipe (6) provided with a throttle valve (5) at a stage subsequent to the center bypass of the center bypass, and branched from a stage before the throttle valve (5).
Is connected to a pump controller (7) of the variable displacement hydraulic pump (1), and a switching valve (13) for selectively connecting or disconnecting the communication between the branch pipeline (6) and the pump controller (7).
a, 13b, 13c), and when the communication is cut off by the switching valve (13a, 13b, 13c), the pilot conduit (11a, 11b) of the pilot switching valve (3) is connected to the hydraulic power source. The warm-up circuit of the hydraulic working machine characterized by the above.