JPS6022202B2 - double acting cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double-acting cylinder used as a loader lift cylinder.

Generally, in a loader, as shown in Fig. 1, a lift cylinder b of a lift arm a and a dump cylinder d of a bucket or a fork, etc. are operated to lower a scooping tool c to the ground, and the scooping angle is In this state, the car body e is moved forward and sand, etc. on the ground surface is scooped into the ball handle c.

However, these lift cylinders b and dump cylinders d are connected in a state where there is no degree of freedom at all with respect to the mounting member and the driven member. Therefore, if the tip of the scooping tool hits a large rock or the like in the ground during marring, the tool will receive a large impact force, and the reaction force will be intensely transmitted to the vehicle body. In this case, since each member is provided with mechanical strength to withstand severe work, there is a risk that the vehicle body and the vehicle may run over and overturn. Even if you try to get over it or back up, it is not easy because the entire vehicle body is on top of it. In addition, with repeated use, the locking tool and the connecting pins of each member become fatigued and damaged at an early stage due to impact loads, resulting in a short lifespan and must be replaced frequently. Sediment on the ground surface,
When accumulating pasture in a field, the ground is not completely flat, but has unevenness all over the place, and the accumulation depth is not constant. Therefore, it is necessary to float the odor. Furthermore, the loader has the following problem. The problem is that it is not possible to adjust the rising height of the dowel according to the load. In other words, in actual use, when the load is light, there is no risk of capsizing even if the load is lifted higher than when it is heavy, but the stroke of the piston rod of the lift cylinder 2 is constant, and the stroke is not safe. In consideration of this, the length is set to correspond to the maximum height when the load is heavy, so it cannot be raised any higher. For example, in the case of an agricultural loader, even if an attempt was made to stack hay and agricultural products, which are lighter than the loader, as high as possible, the height was restricted as described above, and therefore could not be adjusted higher. When the present invention is used as a lift cylinder for a loader, when the lifting odor rises due to the lifting of the lift arm, the lifting height can be safely and automatically adjusted according to the load. This system provides a hydraulic double-acting cylinder that can reduce the impact by retracting the lift arm upward in response to a collision with a rock, etc., and reducing the impact. explain. Second
As shown in the figure, the inner end of the piston rod 4 is inserted into the rod hole 3 formed in the piston 2 in the cylinder 1 so as to be able to move freely in the direction of the koji.

A piston ring 5 is provided between the piston rod 4 and the cylinder wall to maintain airtightness of both chambers of the piston.

Stoppers 6 and 7 are provided on a piston rod 4 with a play interval between them, sandwiching the piston 2. Stopper 6,7
is formed into a ring shape and is iron-bonded to an annular groove formed in the piston rod 4. The rod chamber 8 on the cover side of the cylinder has a tightness that allows the stopper 6 to be inserted therethrough, and a length corresponding to the play distance of the piston 2 between the stoppers 6 and 7. 9 is the hydraulic inlet/outlet on the bottom side of the cylinder, 10
indicates the hydraulic inlet/outlet on the rod side.

The hydraulic cylinder of the present invention is used, for example, as a lift cylinder b of a loader shown in FIG. Attach to the bracket with pin h.

In the state shown in FIG. 2 with the piston rod 4 retracted, pressure oil from the pump is supplied into the cylinder through the inlet/outlet 9, and pressure oil on the rod side is returned to the tank through the inlet/outlet 10.

Then, the piston 2 moves independently on the piston rod 4 as shown in FIG. 3n' and comes into contact with the stopper 6.
Thereafter, the piston 2 and the piston rod 4 move together. Then, the lift arm a rotates and stands up about the pivot pin 1 connected to the post g. The axial thrust of the cylinder at this time is due to the sum of the hydraulic pressure receiving areas of the piston 2 and the inner end surface of the piston rod 4. Next, as shown in FIG. 3, when the t-piston 2 is applied to a part of the cover of the cylinder, the axial thrust is reduced to only the pressure-receiving area of the inner end surface of the piston rod 4. Therefore, when the load is large, for example, when a large amount of earth and sand is scooped up using the mulch c,
The piston rod 4 does not extend any further. However, when the load is 4 mm, for example, when hay or the like is scooped up with the ball handle c, even if the ball thrust is due only to the pressure-receiving area of the inner end surface of the piston rod 4, as shown in FIG. 3 W. The piston rod 4 extends as shown in FIG. and stopper 7
When the piston 2 comes into contact with the piston 2 or the stopper 6 comes into contact with the inner bottom surface of the rod chamber 8, the independent extension of the piston rod 4 is stopped. Next, the inlet/outlet 9 is connected to the tank side, the inlet/outlet 10 is connected to the pump side, pressure oil is supplied to the rod side of the cylinder 1, and the pressure oil in the piston chamber is returned to the tank. Then, if the piston rod 4 still has an extension stroke left, the piston 2 retreats independently until it comes into contact with the stopper 7, and thereafter the piston 2 and the piston rod 4 retreat together. In addition, when the piston rod 4 has no extension stroke left, the piston 2 and the piston rod 4 are immediately connected to each other.
will retreat as one. Extend the piston rod 4 a little,
When lift arm a is erected at an angle, piston 2
The bale rests on the stopper 6 side.

Therefore, when the ball c is hit by a rock or the like during the ball cutting operation, the lift arm a pivots upward about the pin 1 and retreats. That is, the piston rod 4 extends until the stopper 7 abuts the piston 2. In this case, the pressure oil in the piston chamber of the cylinder 1 contains a small amount of air, which is the same as in the pressure oil in the other oil circuits, and therefore the piston rod 4 is in the piston chamber. Even if the hydraulic circuit of is closed, it can be extended as described above. Then, when the ball c passes over the obstacle, the lift arm a descends, and the piston rod 4 independently retracts, returning to the above-mentioned state. As explained above, the present invention is a double-acting cylinder for increasing the protrusion stroke of a piston rod by the amount of free movement when the load is light than when the load is heavy. On the inner surface of the cover around this through hole, a rod chamber capable of accommodating a stopper from the piston is formed to extend an amount equivalent to the free movement distance in the direction of protrusion of the piston rod, and the cylinder moves reciprocally within the cylinder. A piston, a piston rod which is iron-coupled so that the piston can freely move in the axial direction, one end of which protrudes outward from the rod through hole of the cylinder cover, and the end of which is located within the reciprocating chamber of the piston within the cylinder; The stopper is installed on the front and rear piston rods at an arbitrary play interval, sandwiching a movably iron-coupled piston between the two pistons. The protrusion stroke can be automatically increased by the play interval, and when a heavy load is applied, the stroke can be automatically adjusted to be shorter by the play interval.

Furthermore, when the piston rod is stopped in the middle of its protruding stroke, the existence of the play interval allows the piston rod to escape in the protruding direction when the load suddenly increases, thereby preventing impact and damage. Once removed, the original state can be restored. Moreover, these operations can be achieved at low cost with a very simple structure, and can be applied to lift cylinders for raising and lowering lift arms of agricultural front loaders, etc., while ensuring safety (prevention of falling) and expanding the scope of work on the target object. It can achieve particularly remarkable effects.

[Brief explanation of the drawing]

FIG. 1 is a side view of the main parts of the loader, FIG. 2 is a vertical sectional view of a cylinder showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram of its operation. 1...Cylinder, 2...Piston, 3...Rod hole, 4
... Piston rod, 6, 7 ... Stopper, 8 ... Rod chamber, 9, 10 ... Hydraulic inlet/outlet. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 A double-acting cylinder that increases the protrusion stroke of the piston rod by the amount of free movement when the load is light than when the load is heavy, the bottom side is closed, the rod through hole is only on the cover side, and the area around this through hole is closed. A cylinder is formed on the inner surface of the cover with a rod chamber that can accommodate a stopper with a smaller diameter than the piston, extending in the protruding direction of the piston rod by an amount corresponding to the free movement distance, a piston that reciprocates within the cylinder, and the piston is fitted so that it can freely move in the axial direction. A piston rod with one end protruding outward from the rod through hole of the cylinder cover and the other end existing within the piston reciprocating chamber in the cylinder, and a piston fitted so as to be freely movable on the piston rod. A double-acting cylinder characterized by comprising stoppers installed on the front and rear piston rods at arbitrary play intervals.