JPS5851443Y2 - Cylinder - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the improvement of cylinders used in truck cranes, hydraulic excavators, etc.

A conventional truck crane is shown in Fig. 1, and a hydraulic excavator is shown in Fig. 2.

First, a truck crane will be explained with reference to Fig. 1.A is a machine body, b is an arm that is attached to the machine body A so that it can be lifted up and down, C is a drive source device that has a hydraulic power source and a hydraulic motor, and d is a machine that is rotated by the same hydraulic motor. a winding drum, a is a wire rope that extends from the winding drum d along the arm b, and the tip side is suspended from the upper end of the arm b; f is the wire rope a,
and the arm b, the hydraulic motor rotates the take-up drum d to pay out or rewind the wire rope e, and also operates the hydraulic cylinder f in the extending/contracting direction to raise and lower the arm b. Thus, the load W is raised and lowered.

Next, to explain the hydraulic excavator with reference to Figure 2, g is the machine body, h is the boom attached to the machine body g so that it can be lifted up and down, i is the arm that is attached to the same boom h so that it can be rotated, and j is the arm that is pivotable to the same arm i. , k is a hydraulic cylinder installed between the machine body a and the arm h, ■ is a hydraulic cylinder installed between the boom h and the arm i,
m is a hydraulic cylinder installed between the arm i and the excavation packet j; h is a drive source device having an engine and a hydraulic pump; the hydraulic cylinders I and m actuate in the extending and retracting direction; The excavation packet j is elevated and rotated to excavate earth and sand.

In the truck crane, when the hydraulic motor rotates the winding drum d to raise and lower the load W, the wire rope e being pulled by the load W expands and contracts, and the load W arm b, and thus the machine body a, shakes gently. , (I) causes discomfort to the operator.

(If) When the shaking is severe, there is a problem in that the hydraulic cylinder f hydraulic circuit and the like are damaged.

In addition, in the same truck crane and the above-mentioned hydraulic excavator, if the hydraulic control valve installed in the hydraulic circuit between the hydraulic source and the hydraulic cylinder is switched at a high switching speed, the inflow side of the hydraulic cylinder that is increasing or decreasing the load is Pressure oil flows rapidly, and impact pressure is generated on the inflow side, causing the load W arm b of the truck crane and the machine body a, and the excavation packet j of the hydraulic excavator to shake in the same way as above.
I) Causes discomfort to the operator.

(II) Generate impact sound. (1) Drive source (engine,
There was a problem of overloading the system (hydraulic motor).

Note that the above-mentioned impact pressure usually occurs for a few hundredths of a second or a few tenths of a second, and this is plotted on the horizontal axis as time t (see
To further explain with reference to FIG. 3, where m is m5eC),
FIG. 3(I) shows that the operator has sent a switching command to the hydraulic control valve at 1=0.

As a result, the hydraulic cylinder operates from O to S as shown by the solid line in FIG. 3(1).

At this time, pressure oil rapidly flows from the hydraulic source to the inflow side of the hydraulic cylinder, and the internal pressure on the inflow side rapidly rises from O to the target value 11 or more as shown by the solid line in Fig. 3 (2), and then,
When the target amount P1 is below, the above process is repeated multiple times, and the load W arm b of the truck crane and the excavation packet j of the hydraulic excavator operate as shown by the solid line in FIG. 3 (IV), causing the above-mentioned inconvenience.

This proposal addresses the above problems, and includes a piston that divides the inside of the cylinder into an inflow side and an outflow side, a fluid passage leading to the inflow side of the cylinder, a fluid passage leading to the outflow side of the cylinder, and the piston. The poppet valve has a poppet valve that is slidably inserted in an oil-tight manner into a cavity provided in the cylinder, and a throttle passage that communicates the inflow side of the cylinder with the back side of the poppet valve, and the poppet valve has a compression passage. The cylinder is configured such that its front face receives pressure on the inflow side when it is pushed forward by a spring and is seated on the valve seat, and the throttle passage is isolated from the outflow side, and the cylinder has the following features: teeth,
To provide an improved cylinder in which the internal pressure on the inflow side does not exceed a target value even if the switching speed of a fluid pressure control valve provided in a fluid pressure circuit between a fluid pressure source and the cylinder is quickly switched.

As mentioned above, the cylinder of this invention has a piston that divides the inside of the cylinder into an inflow side and an outflow side, a fluid passage leading to the inflow side of the cylinder, a fluid passage leading to the outflow side of the cylinder, and a fluid passage provided in the piston. The poppet valve has a poppet valve that is slidably inserted in an oil-tight manner into the cavity, and a throttle passage that communicates the inflow side of the cylinder with the back side of the poppet valve. When the valve seat is pushed forward and sits on the valve seat, the front face thereof receives pressure on the inflow side, and the throttle passage is isolated from the outflow side, so the fluid pressure control valve is switched at a fast switching speed and the pressure fluid is If it is rapidly sent to the inflow side of the cylinder, the internal pressure on the inflow side will rise rapidly, a peak pressure will be generated on the inflow side, and this peak pressure will act on the front of the poppet valve.

At this time, the oil sealed in the chamber on the back side of the poppet valve and the throttle passage contracts within the elastic range of the oil, and the poppet valve moves by that amount toward the outflow side, moves away from the valve seat, and moves toward the inflow side. The pressure is released to the outflow side, but after that, the oil sealed on the back side of the poppet valve contracts and recovers, so the poppet valve moves toward the inflow side due to the contraction and recovery, seats on the valve seat, and closes the inflow side. The piston moves forward in the direction of the outflow side.

Therefore, even if the fluid pressure control valve is switched quickly, the internal pressure on the inflow side of the cylinder will not exceed the target value.
If applied to truck cranes and hydraulic excavators, the above problems can be solved.

Next, the cylinder of the present invention will be explained with reference to an embodiment shown in FIGS. 4 and 5. 1 is a cylinder, 2 is a piston, 3 is a piston rod, 4 is a packing attached to the piston 2, and 5 is a cylinder.
is a gasket attached to the cylinder 1, 6 and 7 are pressure oil inlets provided in the cylinder 1, 8 is a fluid passage provided in the piston 2, and 9 is a poppet valve provided in the fluid passage 8. The pressure receiving area of the valve 9 is larger on the back side 9b than on the front side 9a.

Further, 11 is a throttle passage connecting the pressure oil inlet side A of the cylinder 1 and the back side 9b of the poppet valve 9, 10 is a throttle provided in the passage 11, and 12 is an inner wall of the piston 2 and the check valve. This is a compression spring interposed between the rear side 9b of the housing 9 and the rear side 9b of the housing 9.

Next, the operation of the cylinder will be explained.

The switching command shown in FIG. 3 (I) is sent to the hydraulic control valve (not shown) provided in the hydraulic circuit between the hydraulic power source (not shown) and cylinder 1, and the hydraulic control valve is switched from O to t'. Turn on the time,
Pressure oil is transferred from the hydraulic source through the inlet port 6 of the cylinder 1 to the inlet side A.
When the cylinder 1 is moved from O to S, the cylinder 1 moves from O to S as shown by the broken line in FIG. 3(1).

That is, when the hydraulic control valve is switched at a faster switching speed,
Pressure oil suddenly flows into the inflow side A of the cylinder 1 from the hydraulic line, and the internal pressure of the inflow side A rises rapidly. A peak pressure is generated on the inflow side A, and this peak pressure is applied to the front side 9 of the poppet valve 9.
It acts on a.

At this time, the chamber on the back side 9b of the poppet valve 9 and the throttle passage 1
The oil sealed in the valve 1 contracts within the elastic range of the oil, and the poppet valve 9 moves in the direction of the outflow side B by that amount, separating from the valve seat and releasing the pressure on the inflow side A to the outflow side. Then, the oil sealed on the back side 9b of the poppet valve 9 contracts and restores, so the poppet valve 9 moves in the direction of the inlet side A due to the contraction and restores, seats on the valve seat, and is connected to the inlet side A. The outflow side B is cut off, and then the piston 2 moves forward in the direction of the outflow side B.

Therefore, the internal pressure on the inflow side A will not rise above the target value P1 as shown by the broken line in Figure 3 Im, and if applied to a truck crane or hydraulic excavator, the behavior of the load and excavation packet will be reduced as shown by the broken line in Figure 3. As shown, the aforementioned rocking is prevented.

Further, when the inflow side A is at normal pressure, the poppet valve 9 does not retreat and the cylinder 1 operates normally.

Furthermore, if a poppet valve mechanism having the same structure as the poppet valve mechanisms 9 to 12 but opposite in direction is provided on the piston 4, the same effect will be achieved when B is on the inflow side.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a conventional truck crane, Fig. 2 is a side view showing a conventional hydraulic excavator, and Figs. The explanatory drawings, FIG. 4, are a vertical side view showing an example of the cylinder, and FIG. 5 is a vertical side view, in an enlarged manner, showing essential parts of one embodiment of the cylinder according to the present invention. 1...Cylinder, 2...Piston, 8
...Fluid passage, 9...Poppet valve, 9
b... Back side, 10°11... Restricted channel, A... Inflow side, B... Outflow side.

Claims (1)

[Scope of utility model registration request] A piston that divides the inside of the cylinder into an inflow side and an outflow side, a fluid passageway leading to the inflow side of the cylinder, a fluid passageway leading to the outflow side of the cylinder, and an oil-tight seal inside the cavity provided in the piston. It has a poppet valve that is movably inserted and a throttle that communicates the inflow side of the cylinder with the back side of the poppet valve, and when the poppet valve is pushed forward by a compression spring and is seated on the valve seat, the front side 1. A cylinder configured to receive pressure on an inlet side; and said throttle passageway being isolated from an outlet side.