JPH0429884B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a heating device for a pilot operating circuit provided in a construction machine such as a hydraulic excavator, and in particular to a heating device for a pilot operating circuit that drives a directional control valve. Regarding a warming device that can be used.

[Prior Art] FIG. 2 is a circuit diagram showing an example of a schematic configuration of a conventional pilot operating circuit.

In this FIG. 2, 1 is an actuator that drives a working machine (not shown), 2 is a pilot-operated directional control valve that controls the drive of this actuator 1, and 3 is connected to this directional control valve 2 to drive the actuator 1. This is a hydraulic pump that supplies pressure oil. 4 is a discharge side circuit that guides the pressure oil of the hydraulic pump 3 to the direction control valve 2; 5 is a return circuit that guides return oil from the actuator 1;
is being communicated to tank 6. A return filter 7 is interposed in the return circuit 5 and filters and cleans the pressure oil discharged from the hydraulic pump 3. The above-mentioned directional control valve 2 includes a movable spool 8, pilot oil chambers 9, 9' arranged at both ends of this spool 8, and arranged within these pilot oil chambers 9, 9'. It has springs 10, 10' that bias the ends of the main body 2a, and a passage 11 communicating with the return circuit 5 in the main body 2a.

Reference numerals 12 and 12' denote pressure reducing valves constituting a pilot valve for driving the directional control valve 2, 13 an operating lever for driving these pressure reducing valves 12 and 12', and 14 a pilot for one of the pressure reducing valve 12 and the directional control valve 2. Oil chamber 9
The pilot pipe 14' connects the pressure reducing valve 1.
2' and the other pilot oil chamber 9', 15 is a pilot pump that supplies pilot pressure to the pressure reducing valves 12, 12', and 16 is a pipe that supplies pressure oil to the pressure reducing valves 12, 12'. 17 is a pipe line for returning pressure oil from the pressure reducing valves 12, 12' to the tank 6;
18 is a pilot filter that filters and cleans the pressure oil discharged from the pilot pump 15; 19;
is a pilot relief valve that sets the pressure of pressure oil supplied to the pressure reducing valves 12, 12'.

In this pilot operating circuit, for example, when the operating lever 13 is tilted to the left from the state shown in FIG.
6. The oil is guided through the pressure reducing valve 12 and the pilot line 14 to the pilot oil chamber 9 located on the left side of the directional control valve 2 in the figure, thereby causing the spool 8 to move to the right against the force of the spring 10'. When the pressure oil in the pilot oil chamber 9 and the force of the spring 10 are balanced, the spool 8 comes to rest. The pressure oil of the hydraulic pump 3 is guided to the actuator 1 via the discharge side circuit 4 and the directional control valve 2, and the return oil from the actuator 1 is guided to the passage 11 of the directional control valve 2.
It is led to the tank 6 via the return circuit 5 and the return filter 7, and thereby the astuteator 1
is driven, and a working machine (not shown) corresponding to this actuator 1 can be driven. Incidentally, when the operating lever 13 is tilted to the right in FIG. 2, the actuator 1 can be driven in the opposite direction to that described above by substantially the same action.

[Problem to be solved by the invention]

However, the conventional pilot operating circuit configured as described above has the following drawbacks.

That is, in cold weather, the pilot pipe 14,
14' and the pilot oil chamber 9 of the directional control valve 2,
The oil in the pilot circuit, including parts 9', etc., is also cooled and becomes more viscous, so even if the operating lever 13 is operated, it takes time for the spool 8 to move by an amount corresponding to the amount of operation of the operating lever 13. This causes a response delay and significantly deteriorates operability. Moreover, the oil that has flowed into the pilot oil chambers 9, 9' does not flow out from the pilot oil chambers 9, 9', so even if the operating lever 13 is operated, the spool 8 will not move in these pilot circuits. Only a corresponding amount of oil flows, and therefore the oil temperature in this pilot circuit does not rise easily, and it takes a long time to eliminate the response delay.

The present invention was made in view of the actual situation in the prior art, and its purpose is to improve the pilot operation by increasing the amount of oil flowing through the pilot circuit and quickly eliminating response delays that occur in cold weather. The purpose is to provide circuit heating equipment.

[Means to solve the problem]

To achieve this object, the present invention includes a hydraulic pump, an actuator driven by the hydraulic pressure discharged from the hydraulic pump, a pilot-operated directional control valve for controlling the drive of the actuator, and a pilot-operated directional control valve for controlling the directional control valve. The pilot oil room was contacted.
a pressure reducing valve that operates a spool of the directional control valve;
It has a pilot pipe line that connects the pressure reducing valve with the pilot oil chamber, and communicates the pressure reducing valve with a secondary side port that communicates with the pilot oil chamber and a tank port that communicates with the tank when in neutral. a communication path which is provided in the pilot operating circuit and which connects the pilot oil chamber with a passage which communicates with the return circuit formed in the directional control valve; A check valve is provided to prevent oil from flowing into the passage from the pilot oil chamber.

[Effect]

Since the present invention has the above-mentioned configuration, when the pressure reducing valve is in the neutral state, by driving the hydraulic pump, the hydraulic pressure discharged from the hydraulic pump is transferred to the passage, the communication passage, and the reverse passage formed in the direction control valve. The amount of oil that flows through the pilot line through the stop valve increases, which increases the oil temperature in the pilot line, and even in cold weather, this pilot operation circuit remains stable. The viscosity of the pressure oil flowing through can be lowered.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a warm-up device for a pilot operating circuit according to the present invention will be explained based on the drawings.

FIG. 1 is a circuit diagram showing a schematic configuration of an embodiment of the present invention. Note that in this figure, the first
Components that are the same as those shown in the figures are designated by the same reference numerals.

In this figure, reference numeral 20 denotes a communication path formed at the left end of the spool 8 in the drawing, which is connected to the passage 11 that communicates with the return circuit 5, and can also communicate with the pilot oil chamber 9 at the left end in the drawing. Reference numeral 21 designates a check valve that is interposed in this communication passage 20 and prevents oil from flowing into the passage 11 from the pilot oil chamber 9, and 22 represents a spring that biases the check valve 21. Although not shown in the drawings, the communication passage 20, check valve 21, and spring 22 are also provided on the right end side of the spool 8. The other configurations are equivalent to those shown in FIG. 2, for example.

In this embodiment, for example, when the operating lever 13 is tilted to the left from the state shown in FIG. As a result, the spool 8 moves to the right in the figure, and the pressure oil from the hydraulic pump 3 is guided to the actuator 1 via the directional control valve 2, and the return oil from the actuator 1 is returned to the directional control valve. 2 passage 11,
It is returned to the tank 6 via the return circuit 5, and the actuator 1 is activated. In addition, operation lever 1
When the actuator 3 is tilted to the right, the actuator 1 operates in the opposite direction to the above-mentioned operating direction due to a similar effect.

Furthermore, when the operating lever 13 is in the neutral position, the pilot lines 14, 14' are connected to the tank 6 via the secondary ports of the pressure reducing valves 12, 12' and the tank port, and there is no oil flow. The pressure in the pilot lines 14, 14' is maintained at tank pressure. On the other hand, the pressure in the passage 11 of the directional control valve 2 is determined by the pressure loss of the return circuit 5, return filter 7, etc., since the return oil of the hydraulic pump 3 reaches the tank 6 via the return circuit 5, return filter 7, etc. The pressure is higher than the tank pressure by that amount. Therefore, if the set pressure of the spring 22, etc. is set to a pressure slightly lower than the above-mentioned pressure loss, the oil in the passage 11 of the directional control valve 2 will flow through the communication passage 20, etc. to the check valve 21 portion. Or it is guided to a check valve part (not shown) provided at the right end of the spool 8,
These check valves 21 or a check valve (not shown) operate against the force of the spring 22, etc., and the oil flows into the pilot oil chambers 9, 9', the pilot pipes 14, 14', the pressure reducing valve 12, 12' and is led to the tank 6 via a conduit 17.

In one embodiment configured in this manner, as described above, by driving the hydraulic pump 3 with the operation lever 13 in the neutral state, the pressure oil of the hydraulic pump 3 flows into the passage of the directional control valve 2. 11. Since it flows to both the pilot pipes 14 and 14' via the communication line 20, these pilot pipes 14,
The amount of oil flowing through the pilot circuits 14, 14', etc. increases, and the oil temperature in the pilot pipes 14, 14', etc. increases, so that even in cold weather, the viscosity of the pressure oil flowing through the pilot circuits can be easily lowered. This makes it possible to realize a smooth flow of pressure oil in the pilot pipes 14, 14', and to eliminate the delay in response to the directional control valve 2 in a short time.

In the above embodiment, the check valve 21, etc., the spring 22, etc. are provided at both ends of the spool 8 of the directional control valve 2, but the present invention is not limited to this. For example, the left end of the spool 8 shown in FIG. Except for the check valve 21 and spring 22 on the side, and the check valve and spring (not shown) on the right end side of the spool 8, the communication passage 20 is formed so that it cannot communicate directly with the passage 11. The main body 2a of the directional control valve 2 is formed to communicate only with the oil chamber 9, and a branch flow path is formed in the main body 2a of the directional control valve 2, which communicates with the above-mentioned passage 11 and which can communicate with the above-mentioned communication passage 20. It is also possible to provide a check valve that prevents pressure oil from flowing into the passage 11 side in the flow path and a spring that biases the check valve, and to provide a similar combination on the right end side of the spool 8. . Even with this configuration, the same effects as in the above embodiment can be achieved.

〔Effect of the invention〕

Since the warm-up device for the pilot operating circuit of the present invention is constructed as described above, the amount of oil flowing through the pilot circuit can be increased compared to the conventional system, and the viscosity of the pressure oil flowing through the pilot circuit can be easily adjusted. Since the response time can be lowered, response delays can be eliminated within a short period of time, which has the effect of improving operability.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a schematic configuration of an embodiment of a warm-up device for a pilot operating circuit according to the present invention, and FIG. 2 is a circuit diagram showing an example of a schematic configuration of a conventional pilot operating circuit. DESCRIPTION OF SYMBOLS 1... Actuator, 2... Pilot operated directional control valve, 2a... Body, 3... Hydraulic pump, 5... Return circuit, 6... Tank, 7...
Return filter, 8...spool, 9,9'...
Pilot oil chamber, 10, 10'...spring,
11... Passage, 12, 12'... Pressure reducing valve, 13...
...Operation lever, 14, 14'...Pilot conduit,
15...Pilot pump, 16, 17...Pipeline, 18...Pilot filter, 20...Connection path, 21...Check valve, 22...Spring.

Claims (1)

[Claims] 1 A hydraulic pump, an actuator driven by hydraulic pressure discharged from the hydraulic pump, a pilot-operated directional control valve that controls the drive of the actuator, and a pilot-operated directional control valve that is connected to the pilot oil chamber of the directional control valve and that controls the directional control. It has a pressure reducing valve that operates a spool of the valve, and a pilot pipe line that communicates the pressure reducing valve with the pilot oil chamber, and connects the pressure reducing valve to a secondary port connected to the pilot oil chamber and a tank. A communication path is provided in a pilot operation circuit formed to communicate with a tank port to be communicated when in neutral, and communicates a passage communicating with a return circuit formed in the directional control valve and the pilot oil chamber. A heating device for a pilot operating circuit, characterized in that a check valve is provided in the communication passage to prevent oil from flowing into the passage from the pilot oil chamber.