JPH0213763Y2 - - Google Patents

Description

[Detailed description of the invention] This invention belongs to the technical field of hydraulic cylinders used in main machines or auxiliary equipment of agricultural machinery such as tractors and front loaders. A piston is fixedly inserted into a cylinder body so as to be able to reciprocate and slide therein, an oil chamber is formed between the piston and at least one cylinder cover within the cylinder body, and a piston rod fixed to the piston is inserted into at least one cylinder cover. protrudes out of the rod hole in a reciprocating manner,
An annular packing groove is formed on the outer circumferential surface of the piston,
Insert a piston seal with a U-shaped cross section into the seal groove.
The present invention relates to a hydraulic cylinder for agricultural machinery, which is fitted with a letter-shaped opening facing toward the oil chamber, and a piston seal seals the reciprocating sliding surface between the piston and the cylinder body.

In recent years, as agricultural machinery has become more versatile, there are more opportunities to replace attachments depending on the work being done. Sometimes foreign matter such as chips or chips remaining during machining of hydraulic parts may get mixed into the hydraulic oil.

In such a case, these foreign objects become lodged in the piston packing inside the cylinder body, causing premature wear or damage to the inner circumferential surface of the cylinder, reducing its durability.

Therefore, in the past, as shown in FIG. 4, the inner peripheral surface 25 of the cylinder body 15 and the piston packing
The gap S between the piston outer circumferential surface 29 on the oil chamber 17 side of the gasket groove 23 into which the gasket 4 is fitted is formed as small as possible to prevent foreign matter in the hydraulic oil from forming between the piston gasket 24 and the inner peripheral surface 25 of the cylinder body 15. There is a hydraulic cylinder 8 which is designed to prevent the hydraulic cylinder 8 from getting caught in the gap, thereby preventing wear on the inner circumferential surface of the cylinder 8 and improving the durability of the hydraulic cylinder 8.

However, although this method can prevent a foreign object larger than the gap S from getting caught, it cannot prevent a thin foreign object from getting stuck, and a sufficient effect cannot be obtained.

It is also possible to remove foreign substances from the hydraulic oil using a filter device before it enters the hydraulic cylinder.
In this case, a high-performance, large-capacity filter must be used that can remove even the smallest foreign particles in large quantities, making it too expensive, making it impractical for use in agricultural machinery with extremely low operating efficiency. isn't it.

The present invention was proposed to solve the above problems, and includes a sliding part between the inner circumferential surface of the cylinder body and the outer circumferential surface of the piston, and a sliding part between the outer circumferential surface of the piston rod and the inner circumferential surface of the rod hole. A packing groove is formed on the outer circumferential surface of the piston at least in the sliding portion between the inner circumferential surface of the cylinder body 15 and the outer circumferential surface of the piston, and a mountain-shaped seal is formed on the sliding side circumferential surface of the packing installed in the packing groove. In addition to forming a sealing lip, a scraper lip is integrally formed in the shape of a mountain at the tip end on the oil chamber side, and the mountain-shaped upper peripheral edges of both lips are brought into elastic contact with the inner peripheral surface of the cylinder body. It is characterized by having a scraper lip that scrapes off foreign matter in the hydraulic oil that adheres to the sliding parts when the piston is sliding, and a sealing lip located behind it to seal it. That is.

The present invention is configured and operates as described above, and thus has the following effects.

In other words, the scraper lip scrapes off foreign matter in the hydraulic oil that adheres to the inner circumferential surface of the cylinder body when the piston slides, so the sliding area between the piston seal and the inner circumferential surface of the cylinder body is free of foreign matter. Smooth sliding can be achieved, preventing premature wear and damage to the piston seal and the inner circumferential surface of the cylinder body due to biting of foreign objects, and greatly improving durability.

In addition, the present invention provides at least a sliding portion between the inner circumferential surface of the cylinder body and the outer circumferential surface of the piston, and a sliding portion between the outer circumferential surface of the piston rod and the inner circumferential surface of the rod hole. A packing groove is formed on the outer circumferential surface of the piston at the sliding part with the outer circumferential surface of the piston, and a chevron-shaped sealing lip is formed on the sliding side circumferential surface of the packing that fits into this packing groove, and the sealing lip is formed on the oil chamber side. The scraper lip is integrally formed in the shape of a chevron at the tip, and the chevron-shaped upper circumferential edges of both lips are made to elastically abut against the inner circumferential surface of the cylinder body, resulting in a simple structure. A single gasket can remove foreign matter and seal oil, and the gasket can be installed and replaced extremely easily and at low cost.

Moreover, in addition to the packing groove provided in the piston at the sliding part between the inner circumferential surface of the cylinder body and the outer circumferential surface of the piston, this packing is also provided in the sliding part between the outer circumferential surface of the piston rod and the inner circumferential surface of the rod hole. When the piston rod is also installed in the packing groove, the outer circumferential surface of the piston rod is prevented from being prematurely worn and damaged by foreign objects, further improving the durability of the hydraulic cylinder.

Additionally, if a small hole is provided between the sealing lip and the scraper lip provided on the outer circumferential surface of the packing to prevent oil from running out, this small hole will allow oil to accumulate between the sealing lip and the scraper lip. The sliding parts between the inner surface of the cylinder body or the outer circumferential surface of the piston rod and the scraper lip and sealing lip are constantly lubricated with hydraulic oil to prevent sticking due to lack of oil in each lip, greatly increasing the durability of the seal. can be improved.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a longitudinal cross-sectional view of a hydraulic cylinder for agricultural machinery. This hydraulic cylinder 8 has a cylindrical cylinder body 15 that slidably accommodates a piston 14. Both front and rear end surfaces of the cylinder body 15 are covered with cylinder covers 16, 16a, and the piston 14 is covered with cylinder covers 16, 16a. Cylinder covers 16, 1 on both front and rear sides of 14
Oil chambers 17, 17 are formed between the two and 6a, respectively.

A cylinder cover 16a attached to the rear end surface of the cylinder body 15 is provided with a pivot hole 18 for pivotally supporting the hydraulic cylinder 8, and an upper part is provided to supply pressure oil from the hydraulic supply pipe 13 to the oil chamber 17 at the rear. An oil passage 19 is provided for supplying the oil.

A cylinder cover 16a attached to the front end surface of the cylinder body 15 has an oil passage 20 for supplying pressure oil from the oil pressure supply pipe 13 to the oil chamber 17 at the front, and a piston rod 21 fixed to the piston 14. A rod hole 22 is provided therethrough.

On the outer peripheral surface of the piston 14 that slides within the cylinder body 15, annular packing grooves 23 are formed near the front and rear oil chambers 17, 17, respectively, and the packing grooves 24 fitted in the packing grooves 23
The outer peripheral surface 29 of the piston 14 and the cylinder body 15
The sliding portion _C1 is configured to slide in a sealed manner with the inner circumferential surface 25 of.

The packing 24 is made of an elastic material such as synthetic resin or rubber and has a U-shaped cross section, and is inserted into the packing groove with the U-shaped opening facing toward the oil chamber. Sliding side peripheral surface 27 of
A sealing lip 26 is formed on the top of the sealing lip 2.
There is a scraper lip 28 on the tip of the oil chamber side from 6.
are integrally formed.

This scraper lip 28 has its peripheral edge 2
8a is attached to the cylinder body 15 by the elastic force of the packing 24.
is brought into pressure contact with the inner circumferential surface 25 of. As shown in FIG. 3, if the shape of the scraper lip 28 is formed so that the peripheral edge 28a that presses against the inner circumferential surface 25 of the cylinder body 15 is sharp, the foreign matter removal performance of the scraper lip 28 can be improved. It gets even higher.

The operation of the hydraulic cylinder 8 formed in this way will be described below.

First, when pressure oil is supplied to, for example, the oil chamber 17 at the rear of the cylinder body 15 by switching the hydraulic pressure switching valve (not shown), the piston 14 slides forward (to the left in the figure) under the hydraulic pressure of the oil chamber 17. The piston rod 21 extends out of the hydraulic cylinder 8. At this time, the scraper lip 28 on the front oil chamber 17 side in the cylinder body 15 slides forward while scraping off foreign matter in the hydraulic oil attached to the inner peripheral surface 25 of the cylinder body 15. Sealing lips 26, 26 that are closer to the rear than the preceding scraper lip 28
is protected from being bitten by foreign objects.

Conversely, when the piston 14 slides rearward (to the right in the figure), the scraper lip 28 near the rear oil chamber 17 touches the inner circumferential surface 25 of the cylinder body 15 that forms the rear oil chamber 17. Since the foreign matter in the hydraulic oil that has adhered is scraped off, foreign matter is prevented from getting caught in the sealing lips 26, 26 between the scraper lips 28, 28 even when the piston 14 slides in either the forward or backward direction. Ru.

In addition, if a small hole for preventing oil draining is provided between the sealing lip 26 and the scraper lip 28, as shown by reference numeral 30 in FIG. Hydraulic oil is stored from the small hole 30 between the sealing lip 26 and the scraper lip 28, and this stored hydraulic oil is used to seal the inner circumferential surface 25 of the cylinder body 15 or the outer surface of the piston rod 21, the scraper lip 28, and the sealing lip 26. The sliding parts S ₁ and S ₂ are constantly lubricated to prevent each lip 26 and 28 from sticking due to lack of oil.

Further, in the above embodiment, the packing 24 provided with the sealing lip 26 and the scraper lip 28 is
The sliding portion C between the inner circumferential surface 25 of the cylinder body 15 and the outer circumferential surface 29 of the piston 14 is provided in the packing groove 23 formed on the outer circumferential surface 29 of the piston C14. As shown, the sliding portion _C2 between the outer circumferential surface 31 of the piston rod 21 and the inner circumferential surface 32 of the rod hole 22 may be attached to a packing groove 23 provided in the inner circumferential surface 32 of the rod hole 22.

Further, the present invention is not limited to the single rod type hydraulic cylinder shown in the embodiment, but may also be a double rod type hydraulic cylinder.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention, with Figure 1 being a longitudinal sectional front view of the hydraulic cylinder, Figure 2 being an enlarged sectional view of the main parts, and Figure 3 showing another embodiment of the scraper lip. FIG. 4 is a partially cutaway longitudinal sectional front view showing a conventional example. 14... Piston, 15... Cylinder body, 1
6, 16a...Cylinder cover, 17...Oil chamber,
21... Piston rod, 22... Rod hole, 2
3...Packing groove, 24...Packing, 26...
Sealing lip, 27...Sliding side circumferential surface of 24, 28
...Scraper lip, 29...outer peripheral surface of 14, 30...small hole.

Claims (1)

[Claims for Utility Model Registration] 1. Cylinder covers 16, 16a are fixed to both end surfaces of the cylinder body 15.
A piston 14 is fitted therein so as to be able to reciprocate and slide, an oil chamber 17 is formed between the piston 14 and at least one cylinder cover 16 within the cylinder body 15, and a piston rod 21 to which the piston 14 is fixed is inserted into at least one cylinder cover 16. Cylinder cover 16
The piston 14 has a packing groove 2 on the outer peripheral surface 29 of the piston 14.
A piston gasket 24 having a U-shaped cross section is fitted into the gasket groove 23 with the U-shaped opening facing toward the oil chamber, and the piston gasket 24 moves back and forth between the piston 14 and the cylinder body 15. In a hydraulic cylinder for agricultural machinery configured to seal the sliding surface, a chevron-shaped sealing lip 26 is formed on the sliding side peripheral surface 27 of the packing 24, and a scraper sealing lip 26 is formed at the tip on the oil chamber 17 side. The lip 28 is integrally formed into a mountain shape, and both lips 26 and 28
A hydraulic cylinder for agricultural machinery, characterized in that a chevron-shaped upper circumferential edge of the cylinder body 15 elastically contacts an inner circumferential surface 25 of a cylinder body 15. 2. Scope of Utility Model Registration In the hydraulic cylinder for agricultural machinery described in claim 1, the packing 24 provided with the oil sealing lip 26 and the scraper lip 28 is attached to the part of the side facing the piston rod 21 of one cylinder cover 16a. It also fits into the packing groove 23 recessed in. 3. In the hydraulic cylinder for agricultural machinery described in claim 1 or 2 of the utility model registration claim, there is a seal between the sealing lip 26 provided on the outer peripheral surface 27 of the packing 24 and the scraper lip 28 to prevent oil running out. A small hole 30 is drilled.