JPH0419221Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates primarily to a filter device used in a hydraulic circuit of a construction machine.

BACKGROUND ART As a conventional hydraulic circuit for construction machinery, the one shown in FIG. 5, for example, is known. In the above hydraulic circuit, the hydraulic pressure discharged from the hydraulic pump a is supplied to the working machine cylinder d via the operating valve c which is switched and controlled by the pilot control valve b, and the return oil from the working machine cylinder d is used for operation. After impurities are removed by a hydraulic oil filter f installed in the oil tank e, the oil is cooled by an oil cooler g and transferred to the hydraulic oil tank e.
It's starting to go back to.

Further, the hydraulic oil filter f is connected in parallel with a safety valve h that bypasses abnormal pressure generated when it becomes clogged, and the oil cooler g is also connected in parallel with a safety valve i that protects it. Of these safety valves h and i, the safety valve h of the filter f is installed above the filter element f installed from above in the hydraulic oil tank e, and the safety valve i of the oil cooler g is installed as shown in FIG. It is attached to the outer surface of the hydraulic oil tank e.

Problems to be solved by the invention In the hydraulic circuit as described above, when inspecting or repairing the operation of the safety valve i of the oil cooler g, the hydraulic oil in the hydraulic oil tank e must be drained each time. There were some problems that required a lot of time and effort to maintain.

This invention was made for the purpose of improving the above-mentioned problems.

Means and operation for solving the problem In a device in which hydraulic oil filtered by a filter element provided in a hydraulic oil tank is cooled by circulating it to an oil cooler, the safety valve connected in parallel to the oil cooler is A filter device that is installed at the bottom of a filter case that houses a filter element so that safety valve adjustment, inspection and repair, etc. can be performed without draining the hydraulic oil in the hydraulic oil tank.

Embodiment This invention will be described in detail with reference to an illustrated embodiment. In the figure, reference numeral 1 denotes a hydraulic oil tank, and a filter case 2 whose upper surface opens onto the upper surface of the hydraulic oil tank 1 is provided inside. A filter element 4 having a safety valve 3 at the upper part is removably housed in the filter case 2, and return oil from a working machine operation valve (not shown) flows into the filter case 2 through a pipe 16. and is filtered by the filter element 4. Further, a cover 18 is removably attached to the upper opening of the filter case 2 with a fixing member 19 via a filter holder 17 as in the conventional case.

On the other hand, a cylindrical valve chamber 6 is fixed to the bottom of the filter case 2. The upper surface of the valve chamber 6 is opened into the filter element 4 housed in the filter case 2, and the hydraulic oil that has passed through the filter element 4 flows into the valve chamber 6. The bottom surface of the oil cooler 7 is closed by a bottom plate 6a, and a safety valve 8 of the oil cooler 7 is screwed into the center of the bottom plate 6a from inside the valve chamber 6.

The safety valve 8 has a short cylindrical main body 8a screwed onto a bottom plate 6a, and a support leg 8b at the center of the main body 8a.
The upper end of the guide rod 8d is fixed to the boss 8c.
A valve body 8e is vertically slidably supported on the guide rod 8d, and a compression spring 8g is interposed between the valve body 8e and a spring seat 8f provided at the lower end of the guide rod 8d. A compression spring 8g urges the valve element 8e to close the lower opening of the valve body 8a.

On the other hand, one end of a conduit 10 is connected to the outer periphery of the valve chamber 6 . The other end of the pipe 10 is connected from the inside to the outflow side 11a of a connector 11 provided on the outer surface of the hydraulic oil tank 1. Connector 1
The outflow side of 1 is connected to an oil cooler 13 through a pipe 12, and the hydraulic oil filtered by the filter element 4 is distributed to the oil cooler 13, and the hydraulic oil cooled by the oil cooler 13 is is adapted to flow into the working tank 1 via the inlet side 11b of the connector 11 through the conduit 14.

A circuit diagram of the above configuration is shown in FIG.

Effects of the invention This invention has been described in detail above, so if the oil cooler 13 is clogged,
When the pressure in the valve chamber 6 leading to valve 3 becomes abnormally high and exceeds the set pressure of the compression spring 8g, the compression spring 8g
The valve body 8e of the safety valve 8 opens against the
In order to release the hydraulic oil inside into the hydraulic oil tank 1,
Damage to the oil cooler 13 due to abnormal pressure can be prevented. Also, by simply removing the cover 18 and filter holder 17 that block the top opening of the filter case 2 and taking out the filter element 4 from the top opening of the filter case 2, the safety valve 8 provided at the bottom of the filter case 2 can be opened. Since it can be easily removed from the opening of the filter case 2, there is no need to drain the oil from the hydraulic oil tank 1 as in the conventional case. It is also possible to prevent secondary contamination such as dirt and the like getting mixed into the oil discharged from 1 and entering the hydraulic oil tank 1 after maintenance.

Moreover, by providing the safety valve 8 in the filter case 2, the structure of the safety valve 8 itself and the hydraulic oil tank 1 can be improved.
Since the structure can be simplified, it can be provided at low cost.

[Brief explanation of the drawing]

The drawings show one embodiment of this invention, with Fig. 1 being a partially cutaway front view, Fig. 2 being a side view of the same, and Fig. 3 being a partially cutaway front view.
4 is a circuit diagram, and FIGS. 5 and 6 are conventional explanatory diagrams. 1 is a hydraulic oil tank, 2 is a filter case, 4 is a filter element, 8 is a safety valve, and 13 is an oil cooler.

Claims (1)

[Scope of utility model registration request] A filter device in which hydraulic oil is filtered by a file element 4 which is removably inserted into the upper surface opening of a filter case 2 provided in a hydraulic oil case 1, and the filtered hydraulic oil is circulated to an oil cooler 13. A valve chamber 6 whose upper surface opens into the filter case 2 is provided at the bottom of the filter case 2, and a valve chamber 6 is provided at the inner bottom of the valve chamber 6 when the hydraulic oil flowing into the oil cooler 13 exceeds the set pressure. A filter device is provided with a safety valve 8 which is detachably installed to discharge water into a hydraulic oil tank 1.