JP3238978B2 - Operating device for directional control valve in mobile crane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for operating a directional control valve in a mobile crane.

[0002]

2. Description of the Related Art A mobile crane is provided with a swing drive for a swivel base,
Hydraulic actuators are used for raising and lowering the boom, driving the winch, and the like. As shown in FIG. 2, the operation of each hydraulic actuator A is controlled by hydraulic oil passing through a direction switching valve 1 of a spring center four-way three-position type. The direction switching valve 1 and an operation lever 2 for switching the direction switching valve 1 are interlocked and connected via a mechanical interlocking system 3.
The direction switching valve 1 is configured to switch from the neutral position to the forward direction and the reverse direction in conjunction with the tilting operation in the forward and reverse directions from the neutral position. Since the operation device of the directional control valve in such a mobile crane directly operates the directional control valve via the mechanical interlocking system 3, the directional control valve can be switched reliably with a simple structure. Has advantages.

The directional control valve 1 (spool of the directional control valve 1) is urged by springs 4 and 4 to be in a neutral position when not operated. As the springs 4 and 4, sufficiently strong springs for securely positioning the directional control valve 1 (the spool of the directional control valve 1) at the neutral position when the directional control valve is not operated are used.

[0004]

Therefore, in the above-described conventional operation device for the directional control valve in the mobile crane, a large operation force is required for the tilting operation of the operation lever 2 and fatigue of the operator of the mobile crane is reduced. It was compelling. In order to reduce the operation force of the operation lever 2, it is conceivable to reduce the spring constants of the springs 4 and 4 and to reduce the initial deflection at the neutral position of the springs 4 and 4. In this case, the directional control valve 1 cannot be reliably located at the neutral position, and such measures are naturally limited. Also,
Pilot pressure generating means (not shown) for generating a pilot pressure corresponding to the tilting operation of the operation lever 2 without connecting the operation lever 2 and the direction switching valve 1 via a mechanical interlocking system 3
The directional control valve 1 is switched by the pilot pressure from the control lever 2, ie, the operation lever 2 and the directional control valve 1
Although it is conceivable to hydraulically interlock and connect, the tilting operation force of the operation lever 2 can be reduced, but fine switching operation cannot be performed due to a delay in switching response of the direction switching valve 1. There is a problem of lack of certainty.

An object of the present invention is to provide an advantage of a conventional operating device in which an operating lever 2 and a directional control valve 1 are interlockingly connected via a mechanical interlocking system 3, that is, to switch the directional control valve 1 reliably with a simple structure. An object of the present invention is to provide an operation device for a directional control valve in a mobile crane in which the tilting operation force of the operation lever 1 is reduced without changing the springs 4 and 4 while maintaining the advantage of being operable.

[0006]

Means for Solving the Problems In order to achieve the above object, an operating device of a directional switching valve in a mobile crane according to the present invention is configured as follows. A directional switching valve 1 for controlling the driving of a hydraulic actuator A for driving a mobile crane, a spring-centered four-way three-position directional switching valve 1 urged by springs 4 and 4 to return to a neutral position. And an operation lever 2 for switching the directional control valve 1 in an interlocking manner via a mechanical interlocking system 3.
An operation device for a direction switching valve in a mobile crane configured to switch the direction switching valve 1 from a neutral position to a forward / reverse direction in response to a tilting operation from a neutral position to a forward / reverse direction from a neutral position, A switching force assist hydraulic actuator connected to the direction switching valve 1 or the interlocking system 3 so that the output of the direction switching valve 1 acts as a switching force from a neutral position to a forward direction and a reverse direction; Pressure generating means for supplying a pilot pressure for generating forward and reverse switching forces to the hydraulic actuator for use, wherein the pilot pressure generating means moves the operating lever 2 from the neutral position in the forward and reverse directions. When the tilting operation of the operating lever 2 is performed from the initial stage to the final stage of the tilting operation of the operation lever 2, the hydraulic activator for switching force is used. The eta generates a switching force in the direction switching valve 1 in the direction corresponding to the tilting operation direction of the operation lever 2 and is smaller than the neutral return force of the direction switching valve 1 by the springs 4 and 4. Operation lever 2,
An operating device for a directional control valve in a mobile crane, which is associated with the interlocking system 3 or the directional control valve 1.

[0007]

The operation device of the directional control valve in the mobile crane according to the present invention having the above-described structure, when the operation lever 2 is tilted in the forward and reverse directions from the neutral position in order to switch the directional control valve 1, the operation is started. During the period from the initial stage of the tilting operation of the operation lever 2 (the stage where the tilting operation is performed by a minute amount from the neutral position) to the final stage (the end stage of the tilting operation),
The pilot pressure is supplied from the pilot pressure generating means to the switching force assist hydraulic actuator, and the switching force in the direction corresponding to the tilt operation direction of the operation lever 2 acts on the direction switching valve 1 from the switching force assist hydraulic actuator. is there. This switching force acts on the direction switching valve 1 by superimposing it on the switching force from the operation lever 1 transmitted to the direction switching valve 1 via the interlocking system 3, so that the operation force of the operation lever 2 is reduced accordingly. It is alleviated. Since the operating force acting on the direction switching valve from the switching force assist hydraulic actuator is set to be smaller than the neutral return force of the direction switching valve 1 by the springs 4 and 4, the switching of the direction switching valve 1 is performed. The operation is performed only depending on the operation force transmitted from the operation lever 2 via the mechanical interlocking system 3.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an operating device for a directional control valve in a mobile crane according to the present invention will be described below with reference to FIG.
Since the operation device of the direction switching valve in the mobile crane of the present invention is obtained by adding a configuration to the conventional operation device, the reference numerals shown in FIG. It shall be incorporated in the description.

FIG. 1 is an explanatory view of an embodiment of a device for operating a direction switching valve in a mobile crane according to the present invention. In FIG. 1, reference numeral 5 denotes a switching force assist which is connected to the direction switching valve 1 (a spool of the direction switching valve 1) so that its output acts as a switching force from the neutral position to a forward direction and a reverse direction. It is a hydraulic actuator. In this example, the switching force assist hydraulic actuator 5 is constituted by a double-acting hydraulic cylinder directly connected to the spool of the direction switching valve 1. However, the switching force assist hydraulic actuator 5 includes an interlocking system. 3, or
The directional control valve 1 may be provided in the main body.

Reference numeral 6 denotes a pilot pressure generating means for supplying a pilot pressure for generating a switching force (output) in the forward and reverse directions to the switching force assist hydraulic actuator 5. When the operating lever 1 is tilted from the neutral position in the forward direction and in the reverse direction, the pilot pressure generating means 6 controls the hydraulic pressure for switching force during the period from the initial stage to the final stage of the tilting operation of the operating lever 1. The actuator generates a switching force in the direction switching valve 1 in the direction corresponding to the tilting operation direction of the operation lever 2 and is smaller than the neutral return force of the direction switching valve 1 by the springs 4 and 4. It is associated with the operation lever 2. Of course, the pilot pressure generating means 6 is provided with the interlocking system 3 or the directional control valve 1 (the spool of the directional control valve 1) so as to function as described above.
It may be related to.

The structure of the pilot pressure generating means 6 shown in FIG. 1 will be described in detail. In FIG. 1, reference numeral 7 denotes a pressure reducing valve for reducing pressure oil from a pressure oil source. 8 is a forward drive oil chamber 5 of the pressure reducing valve 7 and the switching force assist hydraulic actuator 5.
a, which normally connects the forward drive oil chamber 5a to the tank T, receives the switching electric signal, and supplies the reduced hydraulic pressure of the pressure reducing valve 7 to the forward drive oil chamber 5a. This is an electromagnetic switching valve that can be switched to a position where the switching is performed. 9 is a pressure reducing valve 7
And an oil passage connecting the reverse drive oil chamber 5b of the switching force assist hydraulic actuator 5 to the reverse drive oil chamber 5b and the tank T at all times. 7 is an electromagnetic switching valve that can be switched to a position for supplying the reduced oil pressure to the reverse drive oil chamber 5b. 10 is
When the operating lever 2 is tilted from the neutral position in the forward direction,
It is a limit switch that contacts and outputs a switching electric signal to the electromagnetic switching valve 8 during a period from the initial stage to the final stage of the tilting operation of the operation lever 1. When the operating lever 2 is tilted in the reverse direction from the neutral position, the operating lever 2 is in contact with the electromagnetic switching valve 9 during a period from the initial stage to the final stage of the tilting operation of the operating lever, and sends a switching electric signal to the electromagnetic switching valve 9. Output limit switch. The limit switch 10
And 11 are turned off when the operation lever 2 is in the neutral position, that is, when the operation lever 2 is not operated.

The pressure reducing valve 7 is provided with a hydraulic oil chamber 5 for driving the switching force assist hydraulic actuator 5 in a forward direction.
a or a value that generates a switching force slightly smaller than the neutral return force of the direction switching valve 1 by the springs 4 and 4 when supplied to the reverse drive oil chamber 5b.

As described above, in the embodiment of FIG. 1, the pilot pressure generating means 6 includes the pressure reducing valve 7, the electromagnetic switching valves 8, 9,
Although it is constituted by the limit switches 10 and 11, it is not always necessary to constitute as shown in FIG. In short, the pilot pressure generating means 6 operates the operating lever 1 when the operating lever 1 is tilted from the neutral position in the forward and reverse directions.
During the period from the initial stage to the final stage of the tilting operation, the switching force assisting hydraulic actuator applies a switching force to the direction switching valve 1 in a direction corresponding to the tilting operation direction of the operating lever 2, and the springs 4, 4. As long as it is associated with the operating lever 2, the interlocking system 3, or the directional control valve 1 (the spool of the directional control valve 1), a switching force smaller than the neutral return force of the directional control valve 1 due to the directional control valve 1 is generated. is there.

The operating device of the directional control valve in the mobile crane of the present invention constructed as described above, when the operating lever 2 is tilted from the neutral position in the forward or reverse direction, the tilting operation force is applied to the mechanical interlocking system. And the switching force assisting hydraulic actuator 5 applies a switching force in the forward or reverse direction to the directional control valve 1 by the pilot pressure from the pilot pressure generating means 6. Therefore, the tilting operation force of the operation lever 2 can be reduced accordingly.

In the above-described embodiment, the pressure related to the pressure reduction of the pressure reducing valve 7 is fixed. However, the pressure related to the pressure reduction of the pressure reducing valve 7 is changed from the neutral position of the operation lever 2 in the forward direction and in the reverse direction. The higher the amount of tilting operation in the direction, the higher the pressure, and a part or all of the increase in the repulsive force of the spring 4 that is displaced in the forward or reverse direction from the neutral position of the spool of the directional control valve 1. May be covered by the switching force generated by the switching force assist hydraulic actuator 5. That is, the pilot pressure generating section 6 operates the operating lever 2, the interlocking system 3 or the interlocking system 3 so as to generate a pilot pressure that increases in accordance with the amount of switching in the forward and reverse directions from the neutral position of the direction switching valve 1. It may be configured in connection with the directional control valve 1.

[0016]

The operating device for the directional control valve in the mobile crane of the present invention constructed and operated as described above is a reliable operating device in which the operating lever 2 and the directional switching valve 1 are connected by a mechanical interlocking system 3. In spite of this, the simple effect of simply adding the switching force assist hydraulic actuator 5 and the pilot pressure generating means 6 can reduce the tilting operation force of the operation lever 2 and provide an excellent effect of reducing fatigue of the crane operator. Have

[Brief description of the drawings]

FIG. 1 is an explanatory view of an operation device of a direction switching valve in a mobile crane according to the present invention.

FIG. 2 is an explanatory diagram of a device for operating a direction switching valve in a conventional mobile crane.

[Explanation of symbols]

A: hydraulic actuator, 1; directional switching valve, 2; operating lever, 3; mechanical interlocking system, 4, 4; spring, 5;
Hydraulic actuator for switching force assist, 5a; forward drive oil chamber, 5b; reverse drive oil chamber, 6; pilot pressure generating means, 7; pressure reducing valve, 8, 9;
Limit switch,

Claims (2)

(57) [Claims] 1. A directional switching valve 1 for controlling the driving of a hydraulic actuator A for driving a mobile crane, a spring center four-way three-position type urged to return to a neutral position by springs 4 and 4. Directional valve 1
And an operation lever 2 for switching the direction switching valve 1
And a mechanically interlocking system 3 so that the directional control valve 1 is switched from the neutral position to the forward or reverse direction in response to the tilting operation of the operating lever 2 in the forward or reverse direction from the neutral position. The operation device for a directional control valve in a mobile crane constructed as described above, the output of which acts on the directional control valve 1 or the interlocking system 3 so that the directional control valve 1 acts as a switching force from a neutral position to a forward direction and a reverse direction. The switching force assist hydraulic actuator 5 and pilot pressure generating means 6 for supplying a pilot pressure for generating a forward and reverse switching force to the switching force assist hydraulic actuator 5; When the operation lever 2 is tilted from the neutral position in the forward direction and the reverse direction, the pressure generating means 6 starts from the initial stage of the tilting operation of the operation lever 2. During the final stage, the switching force assist hydraulic actuator 5 applies the switching force in the direction corresponding to the tilting operation direction of the operating lever 2 to the direction switching valve 1, and the switching of the direction switching valve 1 by the springs 4, 4. An operating device for a directional control valve in a mobile crane, which is associated with an operating lever 2, an interlocking system 3, or a directional control valve 1 so as to generate a switching force smaller than a neutral return force. 2. The operation lever 2 according to claim 1, wherein the pilot pressure generator 6 generates the pilot pressure that increases in accordance with the amount of switching in the forward and reverse directions from the neutral position of the direction switching valve 1. 3. The operating device for a directional control valve in a mobile crane according to claim 1, wherein the directional control valve is associated with the directional control valve.