JPH07165386A - Safety device for hydraulic construction machine - Google Patents

Abstract

PURPOSE:To prevent a control valve from being switched over even in a case an operation lever is erroneously operated when a hydraulic cylinder is in an operation state. CONSTITUTION:A pair of link members 16 and 17 are arranged on both sides of a hydraulic cylinder 11 movably in the longitudinal direction of a link member and rotatably in the oscillating direction of the hydraulic cylinder 11. The ends on one side of the link members 16 and 17 are rotatably coupled to the piston rod 12 of the hydraulic cylinder 11 through a coupling pin 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a hydraulic construction machine.

[0002]

2. Description of the Related Art Generally, a hydraulic construction machine such as a crane truck is provided with, for example, a hydraulic motor for driving a revolving structure provided on a traveling vehicle body and a hydraulic cylinder for extending and retracting a boom. . These hydraulic actuators are operated by pressure oil supplied from a hydraulic pump, and a control valve is provided in a hydraulic line connecting the hydraulic pump and each hydraulic actuator. These control valves control the pressure oil supplied to the hydraulic actuator, and are switched by an operating lever provided corresponding to the hydraulic actuator.

By the way, in such a hydraulic construction machine, if the swing range of the swing structure driven by a hydraulic motor exceeds a safe range, a fall accident may occur, and therefore, as shown in FIG. Various safety devices are installed to prevent accidents such as falls.

In FIG. 10, reference numeral 1 is a control valve for controlling pressure oil supplied from a hydraulic pump (not shown) to a hydraulic actuator such as a hydraulic motor, and 2 is a spool of the control valve 1. At one end of the spool 2, The operation lever 4 is connected via the connecting pin 3. The operation lever 4 is for switching the control valve 1 and is rotatable in the left-right direction in the drawing with a shaft 5 as a fulcrum.

Reference numeral 6 is a connecting member connected to the operating lever 4 via a pin 7, and 8 is a swinging member connected to one end of the connecting member 6 via a pin 9. A shaft 8 is rotatable in the left-right direction in the drawing with a shaft 10 as a fulcrum.

Further, reference numeral 11 is a fluid pressure cylinder which contracts when the operation amount of the hydraulic actuator exceeds a safe range, 12 is a piston rod of the fluid pressure cylinder 11, 1
Reference numeral 3 is a connecting pin that connects the piston rod 12 and the swing member 8, and the fluid pressure cylinder 11 is rotatable in the left-right direction in the drawing with a shaft 14 as a fulcrum.

In such a structure, when the operation lever 4 is tilted to the left side in the figure, as shown in FIG. 11, the fluid pressure cylinder 11 moves the shaft 12 according to the operation amount of the operation lever 4.
It swings about. At this time, when the operation amount of the hydraulic actuator exceeds the safe range and the piston rod 12, which is the expansion / contraction operation part of the fluid pressure cylinder 11, contracts in the axial direction, the swing member 8 swings clockwise in the figure with the shaft 10 as a fulcrum. Move. As a result, the connecting member 6 moves to the left in the drawing, the operation lever 4 is returned to the normal position, and the spool 2 of the control valve 1 is forcibly returned to the neutral position. Therefore, in the hydraulic construction machine equipped with such a safety device, the operation lever 4 can be returned to the steady position when the operation amount of the hydraulic actuator exceeds the safe range, which allows the control valve 1 to move to the hydraulic actuator. The pressure oil supply can be stopped to ensure integrity.

[0008]

However, as shown in FIG.
The conventional safety device shown in 1 has the following problems. That is, in the conventional safety device, the fluid pressure cylinder 11
And the swinging angle of the fluid pressure cylinder 11 is α, the return force F acting on the operating lever 4 is F = Psinα. For this reason, when the swing angle α of the fluid pressure cylinder 11 is near 0 °, even if the fluid pressure cylinder 11 is operating, almost no return force acts on the operation lever 4.
Therefore, if the operator mistakenly operates the operation lever 4 while the fluid pressure cylinder 11 is in the operating state, the operation lever 4 slightly moves, and as a result, pressure oil is supplied from the control valve 1 to the hydraulic actuator. There is a problem in that the hydraulic actuator is activated due to the above.

The present invention has been made in view of the above problems, and an object thereof is to switch the control valve even if the operating lever is erroneously operated while the fluid pressure cylinder is in an operating state. It is to provide a safety device for a hydraulic construction machine that does not have any.

[0010]

In order to solve the above-mentioned problems, the present invention according to claim 1 is directed to the operation amount of an operation lever for switching a control valve provided in a hydraulic circuit of a hydraulic construction machine. It has an oscillating fluid pressure cylinder,
When the operation amount of a drive unit driven by a hydraulic actuator connected to the control valve via a hydraulic line exceeds a safe range, the telescopic operation unit of the fluid pressure cylinder is operated to move the operation lever to a steady position. In a safety device for a hydraulic construction machine, the pair of link members are provided on both sides of the fluid pressure cylinder so as to be movable in the longitudinal direction of the link member and rotatable in the swing direction of the fluid pressure cylinder. One end of these link members is rotatably connected to the expansion / contraction operation part of the fluid pressure cylinder via a connection pin.

According to a second aspect of the present invention, there is provided a fluid pressure cylinder which swings in accordance with an operation amount of an operation lever for switching a control valve provided in a hydraulic circuit of a hydraulic construction machine. When the operation amount of the drive unit driven by the hydraulic actuator connected to the control valve via the hydraulic line exceeds the safe range, the expansion / contraction unit of the fluid pressure cylinder is operated to bring the operation lever to the steady position. In the safety device of hydraulic construction machine to restore,
A guide member having an arcuate sliding surface is provided at a position facing the expansion / contraction operation part of the fluid pressure cylinder, and the expansion / contraction operation part of the fluid pressure cylinder is brought into contact with the sliding surface of the guide member. It is what

[0012]

According to the first aspect of the present invention, when the operating force of the fluid pressure cylinder is P, the swing angle of the fluid pressure cylinder is α, and the inclination angle of the link member with respect to the swing cylinder is θ, it acts on the operation lever. The returning force F to be performed is represented by F = Psinθcos (θ + α), and when the swinging angle α of the swinging cylinder 11 is near 0 °, F = Psinθcosθ. Therefore, a stronger restoring force than before can be obtained. it can.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those shown in FIGS. 10 and 11 are designated by the same reference numerals, and the description of those parts will be omitted. 1 to 7 are views showing an embodiment of a safety device for a hydraulic construction machine according to the invention described in claim 1, and FIG. 1 is a side view showing a schematic configuration of the device. In the figure, reference numeral 11
Is a fluid pressure cylinder that extends when the operation amount of the hydraulic actuator exceeds a safe range, 12 is a piston rod that is an expansion and contraction operation portion of the fluid pressure cylinder 11, and 13 is a connection that connects the piston rod 12 and the connection member 6. The fluid pressure cylinder 11 is a pin, and is rotatable in the left-right direction in the drawing with a shaft 15 as a fulcrum.

On the piston rod 12 of the fluid pressure cylinder 11, one end of the link members 16 and 17 is connected to the connecting pin 1.
It is connected through 3. These link members 16,
The reference numeral 17 is rotatable in the left-right direction in the drawing with the connecting pin 13 as a fulcrum, and the other end is an elliptical slit 1
8 and 19 are provided along the longitudinal direction of the link members 16 and 17.

Support pins 20 and 21 are provided on both left and right sides of the fluid pressure cylinder 11 in the figure.
These support pins 20 and 21 are the link members 16 and 1.
7, which supports the other end of the link member 16 so as to be rotatable in the left-right direction in the drawing and movable in the longitudinal direction of the link members 16 and 17, and the slits 18 provided at the other ends of the link members 16 and 17, It is loosely fitted in 19.

In such a structure, when the operating lever 4 is tilted to the left side in the drawing, as shown in FIG.
It swings counterclockwise in the figure with the fulcrum as the fulcrum. At this time, when the piston rod 12 of the fluid pressure cylinder 11 extends in the axial direction, the link members 16 and 17 move downward in the drawing as the piston rod 12 extends. Then, if the piston rod 12 tries to extend further in this state,
As shown in FIG. 3, the link member 16 includes the support pin 20.
As a result, the downward movement in the figure is restricted, so that the support pin 20 rotates in the clockwise direction in the figure about the fulcrum. As a result, the operation lever 4 rotates counterclockwise in the figure with the shaft 5 as a fulcrum, and is pushed back to the steady position as shown in FIG.

At this time, the returning force F acting on the operating lever 4
Is the operating force of the fluid pressure cylinder 11, the swing angle of the fluid pressure cylinder 11 is α, and the inclination angle of the link member 16 with respect to the fluid pressure cylinder 11 is θ, then F = Psin θcos (θ + α) When the swing angle α of the fluid pressure cylinder 11 is in the vicinity of 0 °, F = Psinθcosθ, so that a stronger return force than before can be obtained.

On the other hand, when the operating lever 4 is tilted to the right side in the drawing, as shown in FIG. 5, the fluid pressure cylinder 11 swings clockwise in the drawing about the shaft 15 as a fulcrum according to the operation amount of the operating lever 4. . At this time, when the piston rod 12 of the fluid pressure cylinder 11 extends in the axial direction, the piston rod 12
The link members 16 and 17 move downward in FIG. Then, when the piston rod 12 further tries to extend in this state, as shown in FIG. 6, the link member 17 is restricted from moving downward in the figure by the support pin 21, so that the support pin 21 serves as a fulcrum. Rotate counterclockwise. As a result, the operating lever 4 moves to the shaft 5
It rotates clockwise about the fulcrum and is pushed back to the steady position as shown in FIG.

At this time, the returning force F acting on the operating lever 4
Is expressed as F = Psin θcos (θ + α), where P is the operating force of the fluid pressure cylinder 11, α is the swing angle of the fluid pressure cylinder 11, and θ is the inclination angle of the link member 17 with respect to the fluid pressure cylinder 11. When the swing angle α of the fluid pressure cylinder 11 is in the vicinity of 0 °, F = Psinθcosθ, so that a stronger return force than before can be obtained. Therefore, even if the operator mistakenly operates the operation lever 4 when the fluid pressure cylinder 11 is in the operating state, the operation lever 4 does not move, and the operation lever 4 is reliably locked in the steady position. You can

8 and 9 are views showing an embodiment of a safety device for a hydraulic construction machine according to the invention as defined in claim 2,
FIG. 8 is a side view showing a schematic configuration of the device. In the figure, reference numeral 22 is the piston rod 1 of the fluid pressure cylinder 11.
2 is a guide member provided so as to face the piston rod 12 of the fluid pressure cylinder 11.
Is provided with an arcuate sliding surface 23. Reference numeral 24 in the drawing denotes a sliding roller provided at the tip of the piston rod 12.

In such a structure, when the operating lever 4 is tilted to the left side in the drawing, as shown in FIG.
It swings counterclockwise in the figure with the fulcrum as the fulcrum. At this time, when the piston rod 12 of the fluid pressure cylinder 11 extends in the axial direction, a horizontal component force is generated at the front end of the piston rod 12, and this component force returns the operating lever 4 to the steady position.

[0022]

As described above, according to the present invention, the control valve is not switched even if the operating lever is erroneously operated while the fluid pressure cylinder is in the operating state. A safety device can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a safety device for a hydraulic construction machine according to the present invention according to claim 1;

FIG. 2 is an operation explanatory view of the safety device according to the embodiment.

FIG. 3 is an operation explanatory view of the safety device according to the embodiment.

FIG. 4 is an operation explanatory view of the safety device according to the embodiment.

FIG. 5 is an operation explanatory view of the safety device according to the embodiment.

FIG. 6 is an operation explanatory view of the safety device according to the embodiment.

FIG. 7 is an operation explanatory view of the safety device according to the embodiment.

FIG. 8 is a diagram showing an embodiment of a safety device for a hydraulic construction machine according to the present invention as defined in claim 2;

FIG. 9 is an operation explanatory view of the safety device according to the embodiment.

FIG. 10 is a diagram showing a conventional example.

FIG. 11 is a diagram showing a conventional example.

[Explanation of symbols]

 1 ... Control valve 2 ... Spool 4 ... Operating lever 11 ... Fluid pressure cylinder 12 ... Piston rod 16, 17 ... Link member

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[Procedure amendment]

[Submission date] January 12, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] Figure 9

[Correction method] Change

[Correction content]

[Figure 9]

Claims (2)

[Claims] 1. A hydraulic cylinder having a hydraulic cylinder that swings in accordance with an operation amount of an operation lever for switching a control valve provided in a hydraulic circuit of a hydraulic construction machine, the control valve and a hydraulic pipe being provided therebetween. Safety device for hydraulic construction machine that operates the expansion / contraction operation part of the fluid pressure cylinder to return the operation lever to the normal position when the operation amount of the drive part driven by the connected hydraulic actuator exceeds the safe range A pair of link members are provided on both sides of the fluid pressure cylinder so as to be movable in the longitudinal direction of the link member and rotatable in the swinging direction of the fluid pressure cylinder. A safety device for a hydraulic construction machine, which is rotatably connected to a telescopic operation part of a cylinder via a connecting pin. 2. A hydraulic cylinder having a hydraulic cylinder that swings in accordance with an operation amount of an operation lever for switching a control valve provided in a hydraulic circuit of a hydraulic construction machine, the control valve and the hydraulic line being provided between the hydraulic cylinder and the hydraulic cylinder. Safety device for hydraulic construction machine that operates the expansion / contraction operation part of the fluid pressure cylinder to return the operation lever to the normal position when the operation amount of the drive part driven by the connected hydraulic actuator exceeds the safe range In the above, a guide member having an arcuate sliding surface is provided at a position facing the expansion / contraction operation part of the fluid pressure cylinder, and the expansion / contraction operation part of the fluid pressure cylinder is brought into contact with the sliding surface of the guide member. A safety device for hydraulic construction machinery.