JPS6145247Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a directional control system that controls the operating direction and speed of a hydraulic actuator in hydraulic construction machinery such as hydraulic excavators by sliding the spool of a directional control valve by swinging an operating lever. This invention relates to a valve operating device.

There are two typical means for manually operating a directional control valve that controls the operating direction and operating speed of a hydraulic actuator in an operating device such as a hydraulic excavator.

(1) As shown in FIG. 1, means for operating one system of actuators with one operating lever 10 that can swing only in the longitudinal direction (in the direction of arrows 12a and 12b) with respect to the cockpit S.

(2) As shown in FIG.
With one operating lever 10 that can swing in the directions b and 13a, or in the directions of arrows 13a and 13b of the operating lever 10 disposed on the right side, there are a total of two operating levers that correspond to operations in the front-back and left-right directions, respectively.
Means of operating system actuators.

First, a conventional example of (1) above will be explained with reference to FIG.

The spool 2 of the directional control valve 1 is connected to one end of a rod 11, and the other end of the rod 11 is connected to the lower end of an operating lever 10 that can swing about a support shaft 34. Rod 11 of spool 2
There are two spring receivers 7A and 7B at the opposite end.
A spring 8 is attached between both spring receivers 7A and 7B to set a holding force to return the spool 2 to the neutral position and maintain the neutral position, and these are surrounded by a cover 6. It is.
A packing 9 is provided at the end of the valve body of the directional control valve 1 around the spool 2. A port of the directional control valve 1 is connected to a main circuit hydraulic pump 4, an actuator (hydraulic cylinder) 3, and an oil tank 5.

When the operating lever 10 is pulled in the direction of the arrow 12a or pushed in the direction of the arrow 12b, the spool 2 is displaced via the rod 11 against the force of the spring 8, and the operating direction and operating speed of the actuator 3 are controlled.

Although not shown, in the case of (2) above, the operation lever 10 is configured in the same manner as shown in FIG. It is configured to convert the movement of the upper end of the lever 10 in the left-right direction into the movement of the lower end of the lever in the front-back direction.

Here, the operating force of the operating lever 10 will be described. Now, the spring force by the spring 8, the sliding friction force mainly caused by the packing 9, the fluid force (flow force) generated by the pressure oil of the main circuit passing through the directional control valve 1 and acting on the spool 2, etc. The spool operating force including all W _V , operating lever 10,
The converted value of the frictional force acting on the joints related to rod 11 at the lower end position of the operating lever is W _F , and the operating lever 1
If the lever ratio of 0 is i _L and the operating force of the operating lever 10 is F, then F=W _V /i _L +W _F /i _L. Normally, W _V , W _F , i _L are the pulling direction 12a and pushing direction 12b in the front-back direction operation,
Or, in the left-right direction operation, the inner direction (arrow 13a direction in FIG. 2) and the outer direction (arrow 1 in FIG. 2)
3b direction).

When the operator actually operates in such a state, it feels heavier in the pulling direction than in the pushing direction, and heavier in the outer direction than in the inner direction. Therefore, considering operator fatigue from an ergonomic point of view, it is advantageous to make the lever operating force in the pulling direction lighter than that in the pushing direction, and also in the outward direction lighter than that in the inward direction. However, this cannot be achieved with conventional equipment.

The object of this invention is to provide an operating device for a directional control valve that can lightly set the operating force in the pulling direction when operating the operating lever in the front-back direction or in the outward direction in the left-right direction.

This invention consists of a directional control valve that controls the operating direction and speed of a hydraulic actuator, an operating lever that slides the spool of the directional control valve, and a holding force that returns the operating lever to the neutral position and maintains the neutral position. In a directional control valve operating device for hydraulic construction machinery equipped with a spring that sets the It is characterized by the installation of a load applying mechanism.

Next, an embodiment of this invention shown in FIG. 4 will be described. In this figure, the same parts as in FIG. 3 are denoted by the same reference numerals.

One end of a tension spring 14 is provided between the support shaft 34 and the lower end of the operating lever 10 and is pre-tensioned so that a spring force acts in the pulling direction 12a of the operating directions 12a and 12b of the operating lever 10. are connected to each other, and the other end of the tension spring 14 is connected to a fixed part.

Here, the spring load of the tension spring 14 is W _S , the lever ratio regarding the force application point of the tension spring 14 is I _S , and as mentioned above, the spool operating force of the directional control valve 1 is W _V , the operating lever 10 and the rod 11 If the converted value of the frictional force acting on the related joints at the lower end position of the operating lever is W _F and the lever ratio of the operating lever 10 is i _L , then the operating forces Fa and Fb in the operating directions 12a and 12b in FIG. 4 are respectively Fa=W _V /i _L +W _F /i _L -W _S /i _S Fb=W _V /i _L +W _F /i _L +W _S /i _S , and the difference between Fa and Fb is 2×W _S /i _S Fa, that is, the operating force in the 12a direction becomes lighter.

Although not shown, a compression spring may be installed on the rod 11 to be bent in advance, or a compression spring may be installed on the directional control valve 1 to similarly apply a load.

FIG. 5 shows an embodiment in which this invention is applied to a directional control valve equipped with a hydraulic servo mechanism. In this figure, the same parts as in FIG. 4 are represented by the same reference numerals.

The port of the main body 18 constituting the servo mechanism is connected to the hydraulic pump 15 for the auxiliary circuit and the oil tank 17, and a relief valve 16 is provided on the discharge side of the hydraulic pump 15 to prevent the return to the oil tank 17. A relief valve 33 for controlling back pressure is provided in the middle of the piping. One end of an input rod 19 is connected to the lower end of the operating lever 10, and the other end of the input rod 19 is inserted into an axial hole of an output rod 20 connected to the spool 2 of the directional control valve 1. ing. The input rod 19 is supported by a bearing 21 connected to the main body 18, and a packing 32 is provided on the inner peripheral wall of the bearing 21. A passage 28 is provided in the part of the input rod 19 on the output rod 20 side.
9 are provided with holes forming orifices 29,30. A pressure chamber 27 is formed between the left end flange of the output rod 20 and the bearing 21, a chamber 25 is formed between the annular projecting wall 18a in the main body 18 and the flange of the output rod 20,
A chamber 26 is formed between the annular projecting wall 18a and the inner peripheral wall of the main body 18, and a chamber 31 is formed between the right end surface of the input rod 19 and the bottom wall surface of the axial hole of the output rod 20. ing. Pressure oil from the hydraulic pump 15 is introduced into the chamber 25 .

A cover 24 is fixed to the bearing 21, and a spring receiver 2 coupled to the input rod 19 is disposed within the cover 24.
Spring 22 installed between 3A, 23B and both spring receivers
is contained.

Input rod 19 is held in a neutral position by spring 22. At this time, the output rod 20 receives a leftward force due to the hydraulic pressure supplied from the chamber 25 and tries to displace to the left, but as a result, the orifice 30 closes and the orifice 29 opens, so that the pressure oil from the chamber 25 flows into the chamber 27. is introduced, increasing the pressure in chamber 27 and exerting a rightward force on the output rod. When this rightward force becomes larger than the leftward force, the output rod 20 tries to displace to the right, but as a result, the orifice 29 closes and the orifice 30 opens, so that the pressure oil in the chamber 27 flows through the passage 28 and the orifice. 30,
The oil is discharged through the chamber 26 into the oil tank 17, the pressure in the chamber 27 decreases, and the rightward force decreases. In this way, the forces in both left and right directions are eventually balanced at the position where both orifices 29 and 30 are closed (the position shown in the figure).
The output rod 20 will come to a standstill.

When the operating lever 10 is swung in the direction of the arrow 12a to operate the actuator 3, the input rod 19 moves to the left and the orifice 30 opens while the orifice 29 remains closed.
The pressure oil in the chamber 27 is connected to the passage 28, the orifice 30, and the chamber 2.
6 and is discharged into the oil tank 17, where the pressure is reduced. As a result, the hydraulic pressure acting on the output rod 20 becomes unbalanced and the leftward force increases, causing the output rod 20 to move to the left. At the same time, the spool 2 of the directional control valve 1 connected to the output rod 20 also moves to the left. Finally, both orifices 29,
30 is moved to the closed position, and hydraulic pressure in the left and right direction acts on the output rod 20;
The pressure in chamber 27 is determined such that the load required to move spool 2 is balanced, and output rod 20 and spool 2 are stationary.

As described above, in the hydraulic servo mechanism shown in FIG. 5, the pressure in the chamber 27 is maintained so that the hydraulic pressure in both left and right directions acting on the output rod 20 and the force exerted by the spool 2 are always balanced by the opening and closing operations of the orifices 29 and 30. is controlled, input rod 19 and output rod 20
This means that the orifices 29 and 30 maintain the relative positional relationship shown in the drawing, in which both are closed. That is, the output rod 20 is always displaced following the input rod 19 due to hydraulic pressure, and no force for operating the spool 2 is transmitted to the input rod 19.

Therefore, the force necessary to operate the input rod 19 is generated by the spring force of the spring 22, the sliding friction force mainly caused by the packing 32, and the pressure oil passing through the orifices 29 and 30.
The sum of the three fluid forces (flow forces) acting on the input rod (W _V ') and the force generated by the pressure in the chamber 31 acting on the end face of the input rod 19 (W _P ) It becomes the addition of. If the pressure in the chamber 31 is P and the pressure receiving area of the end face of the input rod 19 is A, W _P =A×P.

Therefore, as described above, if the converted value of the frictional force acting on the lever-related joints at the lower end position of the operating lever is W _F and the lever ratio is i _L , then the operation in the directions of arrows 12a and 12b in FIG. The forces Fa and Fb are respectively Fa=W _V ′/i _L −W _P /i _L +W _F /i _L Fb=W _V ′/i _L +W _P /i _L +W _F /i _L , and the relationship between Fa and Fb is Fa, that is, the operating force in the 12a direction becomes lighter by the difference 2×W _P /i _L.

However, in a normal servo mechanism where the operating force is not as heavy as described above, the relief valve 33 is not provided, so the pressure in the chamber 31 is approximately equal to the tank pressure, that is, the atmospheric pressure, and W _P is small enough to be ignored. . In this embodiment of the invention, the pressure in the chamber 31 can be maintained at an arbitrary constant value by means of the relief valve 33, and the force W _P can be set arbitrarily.

Further, although not shown, the pressure in the chamber 31 can be maintained at an arbitrary constant value even if the oil tank 17 has a sealed structure and the inside of the tank is pressurized.

In addition, in the embodiment of this invention, it was explained that a load applying mechanism is installed to lighten the operating force when operating the operating lever on the side where the operating force is desired to be lightened, but conversely, it is explained that the load applying mechanism is installed to reduce the operating force when operating the operating lever in the front-back direction. Alternatively, even if a load applying mechanism is installed that increases the operating force when the operating lever is operated inward in the left-right direction, the operation and effect will not change.

According to this invention explained above, since the operating force can be changed depending on the operating direction of the operating lever, the operating force in the pulling direction in the front-rear operating direction or in the outward direction in the left-right operating direction can be reduced, reducing operator fatigue. can be reduced. This is especially effective when the lever operating force is small. In addition, when installing the operating lever at an angle, the horizontal position of the lever's center of gravity moves away from the fulcrum, and the influence of the lever's own weight occurs.Furthermore, the frictional force of the packing, etc. is added, and the lever does not return to the neutral position due to the spring force of the neutral position return spring. Although a situation may arise in which the lever cannot be returned to its original position, this weight of the lever itself can be compensated for by the load applying mechanism of this invention.

[Brief explanation of the drawing]

Figs. 1 and 2 are explanatory diagrams showing the operating direction of the operating lever in plan view, Fig. 3 is a side view showing an example of a conventional directional control valve operating device, and Fig. 4 is an example of an embodiment of this invention. FIG. 5 is a cross-sectional side view showing another embodiment of this invention. 1... Directional control valve, 2... Spool, 3... Actuator, 4... Hydraulic pump, 5... Oil tank, 7A, 7B... Spring receiver, 8... Spring, 14
...Tension spring, 15...Hydraulic pump for auxiliary circuit,
16... Relief valve, 17... Oil tank, 18...
...Body, 19...Input rod, 20...Output rod, 22...Spring, 23A, 23B...Spring receiver, 29...Orifice, 30...Orifice,
33... Relief valve, 34... Support shaft.

Claims (1)

[Scope of utility model registration request] A directional control valve that controls the operating direction and speed of the hydraulic actuator, an operating lever that slides the spool of the directional control valve, and a spring that returns the operating lever to the neutral position and sets the holding force that maintains the neutral position. In a directional control valve operating device for a hydraulic construction machine equipped with the A directional control valve operating device characterized in that it is installed.