JPH059524Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to improvements in hydraulic circuits used in construction machines such as hydraulic excavators and cranes.

[Conventional technology]

Conventionally, a hydraulic circuit for remotely operating a pilot type switching valve using hydraulic pressure has been constructed using pilot valves 1 and 1' and a pilot type switching valve (hereinafter referred to as a "switching valve"), as shown in Fig. 3.
) 2 are placed at a separate location, and are connected by pilot conduits 3, 3'.
Pilot pipes 3, 3' are connected to the pilot chambers 4, 4' of the switching valve 2, and the spool 6 is controlled by the pilot pressure supplied from the pilot pump 5 through the pilot pipes 3, 3'. is adapted to slide against the elastic force of springs 7, 7'. As a result, pressure oil from the main pump 8 is guided to the actuator 9 through the switching valve 2.

[The problem that the idea aims to solve]

By the way, the amount of pressure oil passing through the pilot pipes 3, 3' is determined by the stroke amount of the pilot chambers 4, 4' and the spool 6, but this amount is not large, and the amount of pressure oil passing through the pilot pipes 3, 3' Since the pressure oil that passes through ' only reciprocates, there is a drawback that there is a large response delay during operation at low temperatures due to the high viscosity of the pressure oil.

Also, even when the temperature is not low, the pilot pipe 3,
3' has a small diameter, the length of the pilot pipes 3, 3' is long, or the pilot chambers 4, 4',
There is also a problem in that the response delay increases when the total volume of bubbles contained in the pressure oil in the pilot pipes 3, 3' is large.

The present invention has been made in view of the actual situation in the prior art described above, and its purpose is to provide a hydraulic circuit that can improve the responsiveness between a pilot valve and a pilot type switching valve in the various cases described above. It is in.

[Means to solve the problem]

In order to achieve this objective, the present invention has developed a hydraulic system in which a pilot valve and a pilot type switching valve are connected through a pilot pipe, and the pilot type switching valve is switched by controlling the pilot pressure by the pilot valve. In the circuit, the pilot chamber of the pilot type switching valve is connected to a hydraulic power source through a communication line different from the pilot pipe line so as to be in constant communication with the oil pressure source, and a throttle means is provided in the communication line,
The throttling amount of this throttling means is set to a throttling amount such that the hydraulic pressure applied to the spool via the pilot chamber and the pilot pipe is smaller than the force of the spring that biases the spool of the pilot valve. It has the configured configuration.

[Effect]

Since the present invention is constructed as described above, the pressure oil from the hydraulic source is constantly supplied to the pilot chamber through a communication path with a throttle means interposed, and the pressure oil in the pilot chamber is connected to a pilot pipe different from the communication path. Since the air flows out from the pilot valve through the pipe, the pilot chamber and pilot pipe are warmed up, and the pilot valve and pilot type switching valve are can improve responsiveness during In addition, since the pressure oil in the pilot chamber and the pilot pipeline is constantly pressurized by the pressure applied through the throttle means, the volume of the air bubbles contained in the pressure oil decreases, and the volume of these air bubbles decreases. The total volume is suppressed to be small, which also improves the responsiveness between the pilot valve and the pilot type switching valve.

As mentioned above, the inside of the pilot chamber and the pilot pipe line are constantly pressurized, but by setting the amount of throttle of the throttle means, a force is generated that is enough to operate the pilot valve spool against the force of the spring. Therefore, it does not have any adverse effect on the operation of the pilot valve.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a first embodiment of the present invention, and the same reference numerals as in FIG. 3 indicate similar components. 1, 1' are pilot valves, 2
3 and 3' are pilot type switching valves (hereinafter referred to as "switching valves") that are switched and controlled by pilot valves 1 and 1', and 3 and 3' are the secondary side (control side) of pilot valves 1 and 1' and the switching valves. 2 is a pilot pipe connecting pilot chambers 4 and 4'; 5 is a pilot valve 1;
Pilot pump connected to the primary side of 1', 6
is a spool of the switching valve 2; 7 and 7' are springs interposed in the pilot chambers 4 and 4' located at both ends of the spool 6; and 8 is a main pump that supplies pressure oil to the actuator 9 through the switching valve 2. Reference numeral 10 denotes a conduit connected to a pilot pump 5 which is a hydraulic pressure source, and this conduit 10 includes a throttle means 11 formed by reducing the opening of a passage provided in the main body of the switching valve 2;
It is connected to the pilot chambers 4, 4' via 11'. The above-described pipe line 10 and the passage provided in the main body of the switching valve 2 constitute a communication path that constantly communicates the pilot pump 5 and the pilot chambers 4, 4'. Further, the throttle means 11, 11' compare the throttle amount with the force of the spring that biases the respective spools of the pilot valves 1, 1'.
4', the amount of throttling is set such that the hydraulic pressure applied to the spool through the pilot pipes 3 and 3' is smaller.

Reference numerals 12 and 13 denote relief valves for setting the discharge pressures of the pilot pump 5 and the main pump 8, respectively.

In the first embodiment thus configured,
When a command is given to one of the pilot valves 1 to be pressed in the direction of the arrow, the pilot pump 5 communicates with the pilot line 3 through the pilot valve 1. As a result, the pressurized oil in the pilot line 3 acts on the pilot chamber 4 of the switching valve 2, and the spool 6 in the switching valve 2 moves to the right in the figure against the spring 7'. The oil in the pilot chamber 4' is discharged to the tank through the pilot line 3 and the pilot valve 1'. By the switching operation caused by the movement of the spool 6, the discharge oil from the main pump 8 is guided to the actuator 9 through the switching valve 2, and the actuator 9 is driven. The operation up to this point is the same as that of the prior art shown in Figure 3 described above.

Pressure oil discharged from the pilot pump (hydraulic source) 5 flows into the pipe line 1 when the pilot valves 1 and 1' are not operated.
0, a small flow rate is always introduced into the pilot chambers 4, 4' through throttle means 11, 11'. This results in
The oil in the pilot chambers 4, 4' is transferred to the pilot pipes 3, 4'.
3' into the tank. Therefore,
Pilot chambers 4, 4' and pilot conduit 3,
The switching valve 2 for the pilot valves 1 and 1' is warmed up early and is used at low temperatures or when the pilot pipes 3 and 3' have a small diameter or a long length.
responsiveness becomes faster.

Further, the pressure oil in the pilot chambers 4, 4' and the pilot pipes 3, 3' is controlled by the throttle means 11, 1.
Since it is constantly pressurized by the pressure applied through 1', the volume of air bubbles contained in the pressure oil is reduced, and the total volume of these air bubbles is suppressed to be small. Also, the responsiveness of the switching valve 2 to the pilot valves 1, 1' can be improved.

Furthermore, as mentioned above, inside the pilot chambers 4, 4',
Although the insides of the pilot pipes 3 and 3' are constantly pressurized, the setting of the throttle amount of the throttle means 11 and 11' allows the spools of the pilot valves 1 and 1' to operate against the force of the spring. It does not generate any force and does not have any adverse effect on the operation of the pilot valves 1, 1'.

In the above embodiment, the switching valve 2 communicating with the pipe line 10
Although the throttling means 11, 11' are provided in the passage formed in the main body of the pipe, the throttling means 11, 11' are not limited to being provided in this manner.For example, the diameter of the pipe line 10 is set small. In this way, restricting means 11, 11' may also be formed.

FIG. 2 shows a second embodiment of the invention. In this second embodiment, the main pump 8 is used as the hydraulic pressure source, and a pressure reducing valve 1 is connected to the main pump 8.
4 interposed between the pipe line 15 and the restricting means 11,1
Pilot chambers 4, 4' are connected through 1'. Note that the pressure reducing valve 14 is connected to the throttle means 11, 11'.
If the amount of aperture is sufficiently large, it may not necessarily be provided. Also in this configuration, the oil discharged from the main pump 8 is guided to the pilot chambers 4, 4' through the pipe line 15, the pressure reducing valve 14, and the throttle means 11, 11', and the oil in the pilot chambers 4, 4' is led to the pilot pipe line 3, 3' into the tank. Therefore, the same effects as in the first embodiment described above are achieved.

[Effect of idea]

According to the hydraulic circuit of the present invention described above, the responsiveness of the pilot type switching valve to the pilot valve at low temperatures can be improved, and the responsiveness can be improved when the pilot pipe has a small diameter or a long length. can also be improved. In addition, it is possible to reduce the volume of air bubbles contained in the pressure oil in the pilot pipe and the pilot chamber, and the total volume of these air bubbles can be made smaller than before. The responsiveness can be improved compared to the previous one.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a first embodiment of the hydraulic circuit of the present invention, Fig. 2 is a circuit diagram showing a second embodiment of the hydraulic circuit of the present invention, and Fig. 3 is a conventional hydraulic circuit. It is a circuit diagram. 1, 1'... Pilot valve, 2... Pilot type switching valve, 3, 3'... Pilot pipe line, 4,
4'...Pilot chamber, 10,15...Pipeline, 1
1, 11'... Squeezing means.

Claims (1)

[Scope of utility model registration request] In a hydraulic circuit in which a pilot valve and a pilot type switching valve are connected by a pilot pipe, and the pilot type switching valve is switched by controlling the pilot pressure by the pilot valve, a pilot chamber of the pilot type switching valve is connected. , connected to a hydraulic power source through a communication line different from the pilot pipe line so as to be in constant communication with the hydraulic power source, a throttle means is provided in the communication line, and the throttle amount of the throttle means is set by energizing the spool of the pilot valve. The hydraulic circuit is characterized in that the amount of restriction is set so that the hydraulic pressure applied to the spool via the pilot chamber and the pilot pipe is smaller than the force of the spring.