JPS5912408Y2 - Hydraulic actuator for raising and lowering work equipment on tractors - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hydraulic actuation device used for raising and lowering a working machine of a tractor.

Conventionally, in tractors, especially small tractors, the rotary work machine descended at a nearly constant speed, so the rotary blade touched the ground with considerable force, and the tractor was driven by the rotational force of the rotary blade, a process known as darting. A phenomenon was occurring.

Therefore, a hydraulic actuator has been proposed that reduces the descending speed of a rotary work machine by constricting the oil drain path during the final stroke of the piston of the hydraulic actuator, which is composed of a piston and a cylinder.

However, even in this hydraulic actuating device, a very fine gap is required in the constricted portion to prevent dashing, and due to its structure, it is difficult to improve the machining accuracy, and there has been no satisfactory product.

Therefore, in the present invention, a throttle valve and an oil passage for adjusting the lowering speed of the work equipment are sequentially provided on the center line of the inner diameter of the cylinder of the cylinder head from the outside toward the inside so that the hole diameter becomes smaller. In addition, by planting a pin of appropriate length in the center of the piston, the opening of the oil passage and the pin can be machined with high precision, and the pin fits into the opening of the oil passage with a minute gap. The object of the present invention is to provide a hydraulic actuating device for lifting and lowering a working machine in a tractor, which eliminates the above-mentioned drawbacks.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

As shown in FIG. 1, the tractor 1 has a body 5 supported by front wheels 2 and rear wheels 3.
An engine 6 is mounted on the front part of the aircraft body 5, and a driver's seat 7 is arranged on the rear part of the aircraft body 5.

Furthermore, a rotary work machine 8 is installed at the rear of the machine body 5.
and is supported by a lift arm 12 via a lift rod 11 so that it can be raised and lowered. The lift arm 12 is rotatably supported by a hydraulic case 15 disposed above a mission case 13 at the rear of the fuselage 5.

The hydraulic case 15 includes a piston 16 as shown in FIG.
The piston 16 is connected to the lift arm 12 via a piston rod 20 and a lift fork 21.

One side of the cylinder 17 is closed by a cylinder head 22, and the cylinder head 22 is closed by the cylinder 17.
The oil passage 23 is positioned so that the opening 23a is located on the center line of the
is drilled.

Furthermore, the oil passage 23 is an oil passage 25 bored in the hydraulic case 15.
It communicates with the hydraulic control valve 26 via the valve 2.
6, the spool 26a is operated by a working machine lifting lever 27 provided on the driver's seat 7.

Further, a throttle valve 28 is provided on the center line of the cylinder 17 of the cylinder head 22, as shown in detail in FIG. Furthermore, one end of the needle 29 protrudes outside the cylinder head 22, and an operating knob 30 is fixed thereto.

The tip of the twenty-one dollar 29 has an angle β smaller than the angle α of the valve seat 31, so the threaded portion 29 of the twenty-one dollar 29 has an angle β smaller than the angle α of the valve seat 31.
The degree of restriction of the oil passage 23 is adjusted by moving forward and backward by a.

On the other hand, a pin 32 is installed in the center of the piston 16, and when the piston 16 approaches the cylinder head 22, the pin 32 is inserted into the opening 23a of the oil passage 23 by 1/100.
They fit together with a gap on the order of (mm).

The length l of the pin 32 corresponds to the piston stroke from the height h just before the rotary work machine 8 touches the ground as shown in Fig. 4b to the maximum plowing depth X as shown in Fig. 4c. The length is 1/1oo [mm] due to the opening 23a of the oil passage 23 that fits with the pin 32.
(7) The precision fitting part a of the order is cylinder head 2.
It is sufficient to provide a few (mm) from the inner end of 2.

Since the present invention has the above-described structure, as shown in FIGS. 2 and 4a, from the state where the rotary work machine 8 is lifted to a height H, by operating the work machine lift lever 27, When the spool 26a of the control valve 26 is moved to the open position, the oil in the cylinder 17 is discharged through the oil passages 23 and 25 by the pressing force of the piston 16 based on the weight of the work implement 8, and the work implement 8 is lowered. .

At this time, since there is a distance between the pin 32 and the opening 23a of the oil passage 23, the cylinder? The oil in the throttle valve 7 rapidly descends according to the degree of restriction of the throttle valve 28.

As shown in FIG. 4b, when the rotary work machine 8 descends to a position h slightly higher than the field, the tip of the pin 32 reaches the opening 23a of the oil passage 23; It fits into part 23a with a slight gap.

As a result, the opening 23a becomes greatly constricted, and the rotary working machine 8 slowly touches the ground and slowly descends to a predetermined plowing depth without causing a dabbing phenomenon.

At this time, in order to reduce the descending speed of the work equipment to the level required to prevent the douching phenomenon, the oil passage 23 shown in FIG.
This is done by accurately controlling the dimensional difference between the opening diameter D and the pin diameter d.

Furthermore, the lift arm angle θ (see FIG. 4b) required to maintain the timing h at which the descending speed of the working machine starts to decrease is set by accurately controlling the length 1 of the pin 32.

Next, a partially modified embodiment will be described based on FIG. 5.

Note that the same parts are given the same reference numerals and the description thereof will be omitted.

In the above-mentioned embodiment, in order to raise the rotary working machine 8 from the lowered position, the oil passage 23 and the pin 32 are used to restrict the working machine 8, so that the rising speed is slow and requires skill to operate.

Therefore, in this embodiment, a branch passage 34 is provided in the cylinder head 22 in parallel with the oil passage 23 provided on the center line of the cylinder head 22, and the oil flows through the oil passage 34 in the direction of inflow into the cylinder 17. A check valve 37 made of a steel ball 35 and a spring 36 is provided in the direction in which oil is discharged.

As a result, the movement of the rotary work machine 8 in the downward direction is the same as in the previous embodiment, but when the rotary work machine 8 moves in the upward direction, pressure oil is supplied to the cylinder 17 via the check valve 37 as shown by the arrow, and the work machine 8 can rise quickly.

The reference numeral 38 shown in Fig. 5 is an adapter for extracting hydraulic pressure, and normally a plug 40 is screwed into this part in order to close a waste hole in oil passage processing, but a docking part attached to the front of the tractor is used. When using another working machine that utilizes hydraulic pressure, such as a loader, the plug 40 can be removed and this hydraulic pressure extraction adapter 38 can be installed.

When using other work equipment, it would be undesirable for the work equipment 8 at the rear of the machine to move up and down at the same time, so the throttle valve 28 should be moved to the valve seat 3.
When the control valve 26 is operated to the upward side, pressure oil is supplied to the cylinder 17 through the check valve 37, and the work implement 8 is raised.
Since it is held in this raised position, it does not interfere with the work of other working machines.

Further, another embodiment will be described based on FIG. 6.

In this embodiment as well, the same parts are denoted by the same reference numerals and the explanation thereof will be omitted.

In the above embodiment, the tractor 71 exclusively used for rotary work has been described, but when the present invention is applied to a large general-purpose tractor, it is used for work below rotary work, such as plow work, so it may sometimes cause the work equipment to fall rapidly. required.

For this reason, in this embodiment, a bypass 41 that communicates the oil passage 23 and the cylinder 17 is provided in the cylinder head 22, and a release valve 42 having the same configuration as the throttle valve 28 is provided in the bypass 41.

As a result, when the bypass 41 is closed by the release valve 42, the pin 32 closes the oil passage 23 as in the previous embodiment.
By fitting into the opening 23a, the descending speed of the working machine can be reduced. However, when the release valve 42 is released and the bypass 41 is opened, the pin 32 is fitted into the opening 23a.
Even if a squeezing action is applied to the fitting, the oil is freely discharged by the bypass 41, so that the working machine can descend rapidly.

As explained above, according to the present invention, the valve seat 31 of the throttle valve 28, which must be machined with high precision, and the valve seat 31 and the threaded portion 2
Concentricity of the female thread part of 9a and the opening 2 of the oil passage 23
3H diameter D:, and the concentricity of the oil passage 23 and the cylinder 17, and the fact that all these holes are aligned with the cylinder head 22.
By arranging the hole diameters that gradually become smaller from the outside in a straight line, it is possible to perform drilling with a full-form drill, making it possible to easily process the cylinder head with high precision.

In particular, the aperture 23a, which requires high precision, is the smallest of all the hole diameters, and the aperture a, which acts as a restrictor, only needs to be a few mm from the innermost part, so it is possible to achieve even higher precision from a processing technology point of view. Can be processed.

Further, the pin 32 can be accurately machined to have its outer diameter dimension d and length l separately from the piston 16, and
Is it also correctly planted in the center of piston 16 in No. 2? I can.

Therefore, since both the opening 23a of the oil passage 23 and the bottle 32 can be machined with high precision, it is possible to obtain a fitting gap on the order of 1/100 (mm), which makes it possible to effectively prevent the dashing phenomenon of the tractor 1. Moreover, even when the piston 16 rotates, the pin 32 can be smoothly fitted into the oil passage opening 23a, so its performance can be maintained for a long period of time.

In addition, since the outer diameter of the cylinder head 22 may be the same as that of the conventional one, the cylinder head 22 and the piston 1
By replacing 6, American tractors can also be equipped with this device.

Furthermore, since a female thread is formed in the large diameter part on the outside of the hole and the throttle valve 28 for adjusting the descending speed of the working machine is screwed therein, the oil passage 23
Since it does not require a stopper to close the end of the valve, and does not have a complicated valve mechanism or mechanical operating part, it can be manufactured at low cost and is easy to maintain.

Furthermore, if the check valve 37 is provided, the working machine 8 can be raised quickly, and the tilling work can be performed with the same driving operation as in the past.

Furthermore, if a bypass 41 is provided that communicates the oil passage 23 and the cylinder 17, and a release valve 42 is provided in the bypass 41, the work equipment can be dropped quickly, and the burau can be quickly moved to the cultivated land during blazing work. Since it can be applied to tasks other than rotary work such as biting, it can also be equipped on medium-sized or larger general-purpose tractors.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a tractor to which the present invention can be applied;
Fig. 2 is a side sectional view showing the hydraulic actuating device according to the present invention, Fig. 3 is an enlarged sectional view showing its different states, Fig. 4 a,
1) and c are operation explanatory diagrams showing different states, FIG. 5 is a side sectional view showing another embodiment, and FIG. 6 is a plan view showing a further modified embodiment. 1...tractor, 16...piston, 17...
Cylinder, 18... Hydraulic actuation device, 22... Cylinder head, 23... Oil passage, 23 a... Opening, 28... Throttle valve, 29 a... Threaded portion, 31...
・Valve seat, 32...: Pin, 37... Check valve, 41
...Bypass, 42...Release valve.

Claims (1)

[Scope of utility model registration request] The cylinder head of the hydraulic actuator is provided with an oil passage having an opening and a throttle valve for adjusting the descending speed of the working machine to adjust the degree of restriction of the oil passage, and a pin of an appropriate length is provided in the center of the piston of the hydraulic actuator. In the hydraulic actuating device for lifting and lowering a work machine in a tractor, the cylinder head is provided with a linear hole that penetrates from the outside to the inside of the cylinder and whose hole diameter gradually decreases on the center line of the cylinder inner diameter of the cylinder head. A female thread is formed in the large diameter part on the outside of the hole, and the throttle valve for adjusting the descending speed of the working machine is screwed therein, and the stepped part of the hole is used as a valve seat for the throttle valve. and a hydraulic actuator for lifting and lowering a working machine in a tractor, further comprising: the opening that fits into the pin at a minimum diameter at the inner end of the hole with a high-precision fitting gap;