JP3107560B2 - Direction switching valve device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a directional control valve device, and more particularly to an improved direction compensating mechanism (hereinafter referred to as a flow controller).

(Prior Art) A conventional example will be described with reference to FIG. FIG. 4 is a hydraulic circuit diagram showing a configuration of a conventional directional control valve device, and has two directional control valves 101 and 103. In addition, hydraulic pumps 105 and 107 are installed, and a tank 109 is installed.

The pressure oil from the hydraulic pumps 105 and 107 is supplied to and discharged from the actuator 110 in an appropriate direction by appropriately switching the direction switching valves 101 and 103.

By the way, the flow switching device 111 is provided in the direction switching valve device. Hereinafter, the function of the floor controller 111 will be described by taking the relationship between the direction switching valve 103 and the floor controller 111 as an example.

First, the direction switching valve 103 has switching positions a and b and a neutral position c. And
By the pilot pressure P _a or the P _b is applied, it switches to the switch position a or b, whereby, the hydraulic pump 10
The pressure oil from 7 is supplied to the actuator 110 from an appropriate direction.

On the other hand, the flow control 111 is switched to the switching position e when the switching positions d and e are provided and the direction switching valve 103 is switched to the switching positions a and b.

That is, the Flocon 111 and pilot pressure P _d from the back side of the pilot pressure P _c and the tank 109 from the discharge side of the hydraulic pump 107 is not applied, the direction switching valve 103 is in the switching position a or b If you are switched, from the difference between the pilot pressure P _c and P _d, since towards the spring force of the compression coil spring 113 is set to be larger, in which switched to the switching position e .

Next, when the direction switching valve 103 switches to the neutral position c, the floor controller 111 switches to the switching position d. This is because the discharge pressure from the hydraulic pump 107 is all pilot pressure P _c
Because they act as the difference between the pilot pressure P _c and P _d is because greater than the spring force of the compression coil spring 113.

Then, in this case, the pressure oil discharged from the hydraulic pump 107 returns to the tank 109.

(Problem to be Solved by the Invention) According to the above-described conventional configuration, there are the following problems.

That is, when the directional control valve 103 is switched to the neutral position c and the pressure oil from the hydraulic pump 107 is returned to the tank 109, a flow control switching pressure is generated in the flow control 111, thereby causing a pressure loss. There was a problem that would occur.

This is for the following reasons. As already mentioned,
When the direction switching valve 103 is switched to the switching position a or b, the floor controller 111 is switched to the switching position e.

That is, the pilot pressures _Pc and P
_This is because the spring force of the compression coil spring 113 is set to be greater than the difference from _d .

At that time, if the discharge pressure from the hydraulic pump 107 increases,
Accordingly, the pilot pressure _Pc also becomes higher, and even in such a case, in order to supply all the discharge oil to the actuator 110 side, the spring force of the compression coil spring 113 is set to be large enough not to lose the pilot pressure _Pc. There is a need to.

As described above, since the spring force of the compression coil spring 113 is set to be large, even when the direction switching valve 103 is switched to the neutral position c and the flow control 111 is switched to the switching position d, the flow control is not performed. Switching pressure is generated, resulting in pressure loss.

The present invention has been made based on such a point, and an object thereof is to reduce the pressure oil loss when the directional switching valve is switched to the neutral position and the pressure oil from the hydraulic pump is returned to the tank. It is an object of the present invention to provide a directional control valve device capable of reducing the pressure.

(Means for Solving the Problems) In order to achieve the above object, a directional switching valve device according to the present invention comprises an operation position for supplying hydraulic oil from a hydraulic pump to an actuator and a neutral position for returning hydraulic oil from a hydraulic pump to a tank. A direction switching valve that switches to an appropriate position by the action of a pilot pressure, and a first switching position and a second switching position interposed between the hydraulic pump and the direction switching valve, When the directional control valve is switched to the operating position, the directional control valve is switched to the second switching position, and the hydraulic oil from the hydraulic pump is supplied to the actuator via the operative position of the directional switching valve, and the directional switching valve is set to the neutral position. A flow controller that switches to the first switching position when switched, and returns pressure oil from the hydraulic pump to the tank via the neutral position of the directional switching valve;
A compression coil spring provided in the flow control and biasing the flow control spool of the flow control in one direction and mounted in the spring chamber, and the direction switching valve slidably housed in the spring chamber is switched to an operating position. In some cases, the piston is slid in one direction by the action of the pilot pressure, and the spring force of the compression coil spring is set large. When the directional control valve is switched to the neutral position, the action of the pilot pressure stops and slides in the other direction. A spring mechanism comprising a piston for moving the compression coil spring to set the spring force to be small, and the pilot pressure is an external pilot pressure, and the pilot pressure acts directly on the spring mechanism. It is assumed that.

(Operation) In the case of the present invention, in the spring mechanism attached to the floor controller, the direction switching valve switches to the neutral position,
When the pressure oil from the hydraulic pump is returned to the tank, the spring force of the compression coil spring that biases the flow control spool of the flow control in one direction is set to be small.
It is intended to reduce the flow control switching pressure and, consequently, the pressure loss.

That is, when the direction switching valve is switched to the operating position, the piston is slid in one direction by the action of the pilot pressure, whereby the spring force of the compression coil spring is set to be large.

On the other hand, when the directional control valve is switched to the neutral position, the action of the pilot pressure stops, and the piston slides in the other direction by the spring force of the compression coil spring. Thereby, the spring force of the compression coil spring is set small.

Therefore, when the directional control valve is switched to the neutral position and the pressure oil from the hydraulic pump is returned to the tank, it is possible to reduce the flow control switching pressure and thus the pressure loss.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a hydraulic circuit diagram showing a configuration of a directional control valve according to the present embodiment. First, the direction switching valves 1 and 3 are provided. The directional control valve 1 has operating positions a ₁ and b ₁ , a neutral position c ₁
It has. Further, the pilot pressure P _a from the pilot valve 5 shown in FIG. 2 from both sides, is P _b is adapted to act.

Then, when the pilot pressure P _a, is P _b does not act, by the compression coil spring 7 and 9 provided on both sides, are switched to the neutral position c _1.

Further, the pilot pressure P _a, by the action of P _b, switched to the switching position a ₁ or b _1, the pressure oil from the hydraulic pump 11 supplies the actuator 13, in which returning the return oil to the tank 15 is there.

On the other hand, the directional control valve 3 has operating positions a ₂ and b ₂ and a neutral position c ₂ . Further, the pilot pressure P _a from the pilot valve 5 already mentioned from both sides, is P _b is adapted to act.

Then, when the pilot pressure P _a, is P _b does not act, by the compression coil spring 17, 19 disposed on both sides, are switched to the neutral position c _2.

Further, the pilot pressure P _a, by the action of P _b, switched to the operating position a ₂ or b _2, the pressure oil from the hydraulic pump 20 supplies the actuator 13, in which returning the return oil to the tank 15 is there.

The pilot valve 5 is provided with switching valves 21 and 23 as shown in FIG.
By switching the 1, 23 appropriately, the pressure oil from the hydraulic pump 25, as the pilot pressure P _a or P _b, to act on the directional control valve 1 and 3. Incidentally, reference numeral 27 in the figure denotes a tank.

Next, the configuration of the floor controller 29 will be described. Flocon
29 has a first switching position d and a second switching position e.
Further, on both sides, the discharge pressure P _c of the hydraulic pump 20, and a back pressure P _d to the tank 15, which acts as a pilot pressure.

A spring mechanism 31 is mounted on the pilot pressure _Pd side. The spring mechanism 31 has a configuration as shown in FIG. First, there is a spring chamber 33, in which the floor controller spool 35 of the floor controller 29 is slidably accommodated.

The flow control spool 35 includes a compression coil spring 37
To the left in the figure. On the right side of the compression coil spring 37 in the figure, a piston 39 is slidably disposed, and on the right side of the piston 39 in the figure,
Pilot pressure P _a or P _b is adapted to effect already mentioned.

That is, the pilot pressure P _a or P _b is, the direction acting on the control valve (3) in the direction when the directional control valve 3 is switched to the operating position a ₂ or b ₂ is the pilot pressure P in the spring mechanism 31 _a or _Pb is acting.

Therefore, the piston 39 is urged to the right in the drawing, and accordingly the spring force of the compression coil spring 37 is set to be large.

In contrast, the pilot pressure P _a or P _b is not acting on the directional control valve 3, when the directional control valve 3 is switched to the neutral position c _2, the pilot pressure to the spring mechanism 31 P _a or P _b does not act.

Therefore, the piston 39 is moving to the right in the drawing, and the spring force of the compression coil spring 37 is set to be small accordingly. This is intended to reduce the pressure loss.

Incidentally, the pilot pressure P _a of the spring mechanism 31, the working channel 41 of P _b is the shuttle valve 43 is interposed. This shuttle valve 43, pilot pressure P _a, P _b is prevented from acting simultaneously.

 The operation will be described based on the above configuration.

First, there directional control valve 3 is in the operating position a _2, illustrating the case that supplies pressure oil from the hydraulic pump 20 to the actuator 13. That is, the pilot pressure P _a from the pilot valve 5 is applied to the directional control valve 3. Thereby, the direction switching valve 3 is switched to the operating position a _2.

On the other hand, in the spring mechanism 31 of the Flocon 29, the pilot pressure P _a are acting, therefore, piston
Reference numeral 39 slides to the right in the figure to increase the set value of the spring force of the compression coil spring 37.

As a result, the pilot pressures P _c and P _d acting on the flow controller 29
The spring force of the compression coil spring 37 is sufficiently larger than the pressure difference between the two, and the floor controller 29 switches to the second switching position e.

Therefore, the pressure oil from the hydraulic pump 20 is
9. The oil is supplied to the actuator 13 via the direction switching valve 3, and the return oil is returned to the tank 15.

Further, the pilot valve 5, the same applies to the case where the pilot pressure P _b is applied.

Next, the case where the directional control valve 3 is switched to the neutral position c _2. That is, the pilot pressure P _a from the pilot valve 5, in order not act any of P _b, by the compression coil spring 17 and 19 switched to the neutral position c _2.

On the other hand, in the spring mechanism 31 of the Flocon 29, the pilot pressure P _a, since P _b does not act, the piston 39 by the compression coil spring 37, is moved to the right in the drawing,
As a result, the spring force of the compression coil spring 37 is set to a small value.

Then, the pilot pressure P _c which acts on Flocon 29, the difference P _d is, becomes larger than the spring force of the compression coil spring 37, it switched to the first switch position d. Thereby, the pressure oil from the hydraulic pump 20 returns to the tank 15.

In the above operation, when the direction switching valve 3 is switched to the neutral position c ₂ is the spring force of the compression coil spring 37 of the Flocon 29 has become small. Thereby, the flow control switching pressure and, consequently, the pressure loss are reduced.

As described above, according to the present embodiment, the following effects can be obtained.

First, the directional control valve 3 is switched to the neutral position c _2, Flocon 29 have switched to the first switch position d, in the case of returning the pressure oil from the hydraulic pump 20 to the tank 15,
Compression coil spring of spring mechanism 31 of floor controller 29
The spring force of 37 can be reduced.

Therefore, it is possible to reduce the flow control switching pressure and thereby reduce the pressure loss.

Further, the spring mechanism 31 of this embodiment, the pilot pressure P _a from the pilot valve 5 provided for the directional control valve 3, since the specifications P _b, there is no need to separately provide a dedicated pilot valve Thus, the configuration can be simplified.

Note that the present invention is not limited to the one embodiment.

For example, a dedicated pilot valve for generating a pilot pressure for switching the piston of the spring mechanism may be separately provided.

(Effect of the Invention) As described in detail above, according to the directional control valve device of the present invention, the directional control valve is switched to the neutral position without impairing the function when the directional control valve is switched to the operating position. In such a case, it is possible to reduce the flow control switching pressure and thus the pressure loss.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a hydraulic circuit diagram showing a configuration of a directional control valve device, FIG. 2 is a hydraulic circuit diagram of a pilot valve, and FIG. FIG. 4 is a sectional view showing the configuration of the elastic mechanism, and FIG. 4 is a hydraulic circuit diagram showing the configuration of a conventional directional switching valve device. 3 ... Directional switching valve, 13 ... Actuator, 15 ... Tank, 20 ... Hydraulic pump, 29 ... Flocon, 31 ... Spring mechanism, 35 ... Flocon spool, 37 ... Compression coil spring, 39 ... Piston, P _a , P _b … Pilot pressure, a ₂ , b ₂ … Operating position, c ₂ … Neutral position, d… First
Switching position, e... Second switching position.

Claims (1)

(57) [Claims] 1. A direction switch that has an operation position for supplying hydraulic oil from a hydraulic pump to an actuator and a neutral position for returning hydraulic oil from a hydraulic pump to a tank, and switches to an appropriate position by the action of pilot pressure. A first switching position and a second switching position interposed between the hydraulic pump and the direction switching valve, and switching to the second switching position when the direction switching valve switches to the operating position. In other words, the pressure oil from the hydraulic pump is supplied to the actuator via the operating position of the directional control valve, and when the directional control valve is switched to the neutral position, the pressure is switched to the first switching position and the pressure from the hydraulic pump is changed. A flow controller for returning oil to the tank via the neutral position of the directional control valve; a compression coil spring provided in the flow controller and biasing a flow control spool of the flow controller in one direction and mounted in a spring chamber; When the directional control valve is slidably housed in the spring chamber and is switched to the operating position, the directional control valve slides in one direction by the action of the pilot pressure to set the spring force of the compression coil spring large, And a piston mechanism that stops the operation of the pilot pressure when the switch is switched to the neutral position and slides in the other direction to reduce the spring force of the compression coil spring. Is a directional switching valve device, wherein is an external pilot pressure, and the pilot pressure acts directly on the spring mechanism.