JPS59137601A - Tank device for hydraulic device - Google Patents

Abstract

PURPOSE:To prevent malfunction due to the suction of air, by surrounding a suction filter with the use of a cover formed at its top end bottom ends with openings communicated with the inside of a tank body. CONSTITUTION:A suction filter 27 disposed in a tank body 11 in the vicinity of bottom of the latter is surrounded by a cover 17 formed at its top end and bottom end, with openings 23, 25 which is communicated with the inside of the tank body 11. The stream U of hydraulic oil entering into the inside of the cover 17 through the opening 25 is balanced with the stream V of air entering into the inside of the cover 17 through the opening 23, the level of hydraulic oil in the tank body 11 is so maintained that the oil level in the cover 17 which is indicated as P' is sustained to be slightly lower than the level of oil outside the cover 17 which is indicated as P while both oil levels are uniformly lowered. Accordingly, only hydraulic oil may sucked into the tank body 11 with no air until a predetermined oil level is obtained, thereby malfunction of a hydraulic device due to generation of cavitation may be surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic oil tank device for a hydraulic device for driving a cargo handling device in an industrial vehicle.

A conventional tank device of this type is shown in FIG. 1 and FIG. 3. Forklift 1-@ industrial vehicle 1
A tank device 3 is formed on a vehicle body 2. l'L, This tank device 3 contains a tilt cylinder 58 for tilting the mast 4 in front of the vehicle body 2, and a lift cylinder 5b for lifting and lowering the mast 4 and the fork carriage 6. Contains hydraulic oil. As shown in FIGS. 2 and 3, the tange device 3 includes a tank body 7 formed by arc welding a U-shaped outer plate 7a and a U-shaped inner plate 7b around the entire circumference, and an inner portion of the tank body 7. It consists of a suction filter 8 fixed to a side wall 7C near the bottom, and a suction pipe 9 communicating with the filter 8 from the side wall 7C and connected to an oil pump (not shown).

Therefore, by driving the oil pump, the hydraulic oil in the tank body 7 passes through the filter and the suction pipe 9 to operate the chill 1 cylinder 5a and the rif 1 cylinder 5b.

Note that 10 in the figure is an oil supply portion formed on the upper surface of the tank body 7.

However, in such a tank device, when the hydraulic oil is sucked from the suction filter 8, if the hydraulic oil level drops to near the filter 8, the hydraulic oil around the filter 8 of the tank body 7 is sucked in first, and the hydraulic oil Since the surface partially drops as shown in Fig. 3P, air is sucked in before the hydraulic oil level has fallen sufficiently, causing cubitation, which may cause malfunction of the tilt cylinder 5a and lift cylinder 5b. There is.

The present invention has been made in view of these conventional problems, and an object of the present invention is to provide a hydraulic oil tank device that can prevent malfunction of a hydraulic device due to air intake with a simple structure.

In order to achieve this purpose, a suction filter placed near the bottom of the tank body is covered with a cover, and openings that communicate with the tank body are formed at the top and bottom ends of the cover, and are activated when hydraulic oil is sucked. The curved surface moves up and down evenly so that only hydraulic oil can be sucked in without sucking air up to a predetermined hydraulic oil level.

Examples shown in the drawings will be described below.

In FIGS. 4 to 7, 1l is a tank body formed by arc welding two U-shaped plates 13, 15 around the entire circumference, and 17 is a side wall 19 and a bottom wall 2l at the bottom of the tank body 11. This cover 17 is welded to the approximately L-shaped plate 1 as shown in FIG.
7a and a side plate 17b fixed to one side L of the plates 1 to 17a, and a through hole 2 as an opening communicating with the inside of the tank body 17 is formed on the upper surface of the plate 17.
3 is opened, and a gap 25 is formed at the lower end of the side as an opening that also communicates with the inside of the tank body 11.

27 is housed inside the cover 17, and one end is connected to the tank body 11.
A suction filter 27 is welded to the side wall 19 of the suction filter 27, and a suction tube 29 communicates with the side wall 19 and is connected to an oil pump (not shown). 3l is a side wall 19 between the cover 17 and the suction filter 27 so as to cover the suction filter 27;
This is the suction canopy attached to the.

Reference numeral 33 indicates an oil supply portion formed on the upper surface of the tank body 11.

With this configuration, when the oil bomb is driven to suck the hydraulic oil in the tank body 11 through the suction filter 27 and the suction pipe 29 and supply it to a hydraulic device such as a chinoreto cylinder or a lift cylinder (see Fig. 1). As shown in FIG. 7, the flow U of hydraulic oil entering the cover 17 from the gap 25 and the flow V of air entering the cover 17 from the through hole 23 are balanced, and the hydraulic oil level in the tank body 11 is increased. The oil level indicated by P' in the cover 17 is the cover 1.
The entire oil level drops uniformly while maintaining a position slightly lower than the oil level shown by P outside 7. Therefore, only the hydraulic oil can be sucked in up to a predetermined hydraulic oil level without sucking in air, and malfunction of the hydraulic system due to cavitation can be reliably prevented.

In addition, when the hydraulic oil returns to the tank body 11 through the return pipe (not shown), the flow U of the hydraulic oil into the bar 17 and the flow h of air pushed out from the cover 17 are balanced, and the cover 17 Cover 1 is slightly delayed from the outside hydraulic oil level P.
The hydraulic oil level P' in 7 rises uniformly.

Other embodiments are shown in FIGS. 8 and 9. In this example, the cover 17' is comprised of a flat plate 17'a and a side plate 17 welded to one end of the plate hl7'a.
'b, and the front and rear ends of the plate 17'a are directly welded to the side wall 19 of the tank body 11 to cover the suction filter 27. And play 1-
A through hole 23' is formed in the upper surface of the tank 17'a, and a gap 25' is formed between the side plates 1 to 17'b and the bottom wall 21 of the tank body.

The operation of this embodiment is also similar to that of the previous embodiment.

As described above, according to the present invention, air is no longer sucked through the suction filter, and the hydraulic system does not malfunction and the smooth operation of the hydraulic system can be ensured, which is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of a forklift truck, and FIGS.
゛The side sectional view and Figures 4 to 7 show an embodiment of the present invention, with Figure 4 being a perspective view and Figure 5 being a side sectional view.
6 is a perspective view of the cover, FIG. 7 is a side sectional view, and FIGS. 8 and 9 show other embodiments.
The figure is a perspective view, and FIG. 9 is a sectional view taken along the line IX-IX in FIG. 8. 11... Tank body, 17, 17'... Cover, 2
3.23'...Through hole (opening), 25.25'...
・Gap (opening), 27...Suction filter. Applicant Nissan Motor Co., Ltd. Representative Patent Attorney Tami Nishiwaki mrζ Koichi 4-

Claims (1)

[Scope of Claims] A tank body, a cover fixed to the bottom of the body and having an opening that communicates with the tank body at each of the upper surface and the lower side end plate, and a suction filter covered by the force 8; ．． A tank device for a hydraulic system, comprising a suction pipe S2 connected to the suction filter.