JP4299932B2 - Return filter device for hydraulic system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a return filter device for a hydraulic system mounted on, for example, a construction machine.
[0002]
[Prior art]
A conventional return filter device for a hydraulic system mounted on a construction machine or the like is configured as shown in FIG. That is, reference numeral 1 in the figure denotes a filter head, and an oil inlet 2 is provided on the side wall of the filter head 1. The filter head 1 is integrally provided with a connecting cylinder 3 that opens in a direction perpendicular to the oil inlet 2. An upper end opening of a cylindrical filter case 4 is fitted and fixed to the connecting cylinder 3, and an oil outlet 5 is provided at the lower part of the filter case 4.
[0003]
A step portion 6 is provided on the inner peripheral surface of the connection cylinder 3, and a flange portion 8 of the valve support cylinder 7 is locked to the step portion 6, and the valve support cylinder 7 is located inside the connection cylinder 3. Concentrically supported.
[0004]
A cylindrical filter element 9 housed inside the filter case 4 is provided below the valve support cylinder 7. An upper end portion of the filter element 9 is supported by an upper plate 10 fitted to the valve support cylinder 7, and a lower plate 11 that closes the lower end opening of the filter element 9 is provided at the lower end portion.
[0005]
A center shaft 12 is provided in the axial center portion of the filter element 9 so as to penetrate the inside thereof, and a lower end portion of the center shaft 12 is supported by the lower plate 11. The upper end portion of the center shaft 12 extends through the valve support cylinder 7 to the inside of the filter head 1, and a screw portion 13 is formed at the upper end portion.
[0006]
A leaf spring member 14 that is bent in the vertical direction is fixed to the screw portion 13 of the center shaft 12 by a double nut 15, and the leaf spring member 14 closes the flange portion 8 of the valve support cylinder 7 and the opening 16 of the filter head 1. The cover 17 is interposed in a compressed state. Therefore, the valve support cylinder 7 is pressed against the step portion 6 by the spring force of the leaf spring member 14.
[0007]
Further, a relief port 18 is formed in a part of the flange portion 8 of the valve support cylinder 7, and a relief valve 19 fitted to the valve support cylinder 7 so as to be movable up and down is provided in the relief port 18. ing. The relief valve 19 is urged in a direction to close the relief port 18 by a coil spring 20 provided so as to surround the valve support cylinder 7.
[0008]
Accordingly, the center shaft 12 is integrally provided with the filter element 9 including the upper and lower plates 10 and 11, and the valve support cylinder 7 including the relief valve 19, and by removing the cover 17 and removing the leaf spring member 14, It is configured to be able to be pulled out integrally from the opening 16.
[0009]
According to the return filter device for a hydraulic system configured as described above, when oil flows into the filter head 1 from the oil inlet 2, the oil passes through the valve support cylinder 7 and into the filter element 9. After that, it passes through the filter element 9 and is guided to the oil outlet 5 through the inside of the filter case 4. At this time, the foreign matter contained in the oil is captured by the filter element 9.
[0010]
Further, when the oil pressure flowing into the filter head 1 from the oil inlet 2 is high and the pressure received by the relief valve 19 via the relief port 18 exceeds the urging force of the coil spring 20, the coil spring 20 is compressed and the relief valve 19 retreats and the relief port 18 opens. Accordingly, the oil in the filter head 1 is guided to the oil outlet 5 through the filter case 4 outside the filter element 9 through the relief port 18 so that the filter element 9 is protected.
[0011]
[Problems to be solved by the invention]
By the way, in the return filter device for a hydraulic system configured as described above, it is necessary to periodically replace the filter element 9. In this case, first, after removing the cover 17, the leaf spring member 14 from the center shaft 12. The valve support cylinder body 7 including the filter element 9 including the upper and lower plates 10 and 11 and the relief valve 19 is removed to the outside by removing the center shaft 12 and lifting the center shaft 12 upward. Therefore, the replacement of the filter element 9 is troublesome and takes a lot of time.
[0012]
In addition, since the coil spring 20 is provided so as to surround the valve support cylinder 7 and the relief valve 19 is biased, the outer diameter of the spring is increased, and the spring coefficient is the same. There is a problem that the spring wire diameter needs to be increased, which is structurally complex and increases the cost of parts.
[0013]
The present invention has been made paying attention to the above circumstances, and the object of the present invention is to provide a return filter device for a hydraulic system that can be easily replaced with a filter element and that is structurally simple and can reduce costs. Is to provide.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a filter head 21 having an oil inlet 22 on a peripheral side wall and an upper opening 23 and a lower opening 24 opposed to each other in the upper and lower parts, An upper end opening is connected to a cover 26 that can be opened and closed in the upper opening 23 of the filter head 21 and a lower opening 24 of the filter head 21, and communicates with the inside of the filter head 21. A filter case 27 having an inner diameter 31, and oil detachably provided in the filter case 27 and supported by the bottom of the filter case 27 from the inside to the outside. A cylindrical filter element 32 having an upper opening that flows out from the oil outlet 31 and captures foreign matters contained in the oil, and the filter element An element plate 34 that is fixed to the nozzle 32 and has an opening 36 that faces the lower opening 24 of the filter head 21, and whose outer peripheral portion is liquid-tightly sealed by an inner peripheral portion of the filter head 21 and a seal member 38. A relief port 40 that bypasses the opening of the element plate 34 and communicates with the outside of the filter element 32, and a relief valve 44 for protecting the element is provided in the relief port 40, The relief port 40 and the relief valve 44 are retracted and positioned outside the upper and lower openings 23 and 24 of the filter head 21,
The filter element 32 is detachable from the upper opening 23 of the filter head 21 together with the element plate 34.
[0016]
According to the first aspect, when oil flows in from the oil inlet of the filter head, the oil pressure is applied to the filter element via the filter plate, but the force can be received at the bottom of the filter case. Accordingly, the center shaft and the upper and lower plates are not required, and the configuration can be simplified.
[0017]
Furthermore, by providing a relief port and a relief valve for protecting the element on the side wall of the filter head, only the filter element can be taken out regardless of the relief valve when replacing the filter element.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 shows a return filter device for a hydraulic system mounted on a construction machine or the like. In the figure, reference numeral 21 denotes a filter head formed by aluminum die casting or the like, and an oil inlet 22 is provided on the side wall of the filter head 21. ing. The filter head 21 is provided with an upper opening 23 and a lower opening 24 that open in a direction perpendicular to the oil inlet 22.
[0020]
The upper opening 23 is closed by a cover 26 fixed to the filter head 21 by a bolt 25, and a flange portion 28 provided at the upper end opening of the cylindrical filter case 27 is fixed to the opening edge of the lower opening 24 by a screw 29. Has been. The lower end opening of the filter case 27 is closed by a bottom portion 30 made of a plate such as aluminum die cast. Further, an oil outlet 31 is formed in the outer peripheral edge of the bottom 30.
[0021]
A cylindrical filter element 32 is concentrically housed inside the filter case 27. The filter element 32 is provided at a cylindrical filtration member 33 that captures foreign matters contained in oil, an element plate 34 provided at the upper end opening end of the filtration member 33, and a lower end opening end of the filtration member 33. And a lower plate 35 having an arcuate convex portion 35a at the center. Further, the outer periphery of the filtering member 33 is covered with an outer cylinder 33a having innumerable through holes.
[0022]
The lower plate 35 constituting the filter element 32 is supported on the bottom 30 of the filter case 27. The element plate 34 has an annular shape and is provided with an opening 36 that allows the inside of the filter head 21 and the inside of the filter member 33 to communicate with each other so that the inside of the filter head 21 and the inside of the filter case 27 are blocked at the peripheral edge. Yes. Further, an annular groove 37 is provided in the outer peripheral portion of the element plate 34, and a seal member 38 that seals the inner peripheral portion of the filter head 21 in a liquid-tight manner is accommodated in the annular groove 37.
[0023]
Further, a handle 39 is attached to the upper portion of the element plate 34 so as to straddle the opening 36, and the filter element 27 can be pulled up by holding the handle 39.
[0024]
A relief port 40 is provided on the side wall of the filter head 21 facing the oil inlet 22, bypassing the opening 36 of the element plate 34 and communicating with the inside of the filter case 27 outside the filter element 32. A side wall having the relief port 40 is surrounded by a valve box 41, and a relief passage 42 is formed therein.
[0025]
Inside the valve box 41, there is provided a relief valve 44 for protecting the element which can be moved forward and backward with respect to the relief port 40 by a valve pin 43, and this relief valve 44 is urged by a coil spring 45 in a direction to close the relief port 40. ing.
[0026]
According to the return filter device for a hydraulic system configured as described above, when oil flows into the filter head 21 from the oil inlet 22, the oil is guided into the filter element 32 through the opening 36 of the element plate 34. After that, it passes through the filter member 33 of the filter element 32 and is guided to the oil outlet 31 through the inside of the filter case 27. At this time, the foreign matter contained in the oil is captured by the filter member 33 of the filter element 32.
[0027]
At this time, the element plate 34 receives a pressing force downward (arrow A) by the hydraulic pressure, and the filter element 32 is also pressed downward by the pressing force. However, the filter element 32 is supported by the bottom 30 of the filter case 27. .
[0028]
Further, when the oil pressure flowing into the filter head 21 from the oil inlet 22 is high and the pressure received by the relief valve 44 via the relief port 40 exceeds the urging force of the coil spring 45, the coil spring 45 is compressed and the relief valve 44 retreats and the relief port 40 opens. Therefore, the oil in the filter head 21 is guided from the relief port 40 through the relief passage 42 to the oil outlet 31 through the filter case 27 outside the filter element 32, and the filter element 32 is protected.
[0029]
In addition, the filter element 32 needs to be periodically replaced. However, when replacing the filter element 32, the bolt 25 is loosened and the cover 26 is removed from the filter head 21. Next, by putting a hand through the upper opening 23 and pulling it up with the handle 39, the filter element 32 including the element plate 34 can be taken out to the outside, and the filter element 32 can be easily replaced. is there.
[0030]
Further, by providing the relief port 40 and the element protecting relief valve 44 on the side wall of the filter head 21, only the filter element 32 can be taken out regardless of the relief valve 44 when the filter element 32 is replaced. .
[0031]
In addition, by providing the relief port 40 and the element protecting relief valve 44 on the side wall of the filter head 21, the spring outer diameter of the coil spring 45 can be reduced and the spring wire diameter can be reduced. Cost can be reduced.
[0032]
【The invention's effect】
As described above, according to the first aspect, when oil flows in from the oil inlet of the filter head, the oil pressure is applied to the filter element via the element plate, and the force is applied to the bottom of the filter case. Can receive. Accordingly, there is no need for the center shaft and the upper and lower plates, and the structure can be simplified. Furthermore, by removing the cover of the upper opening of the filter head, the filter element can be pulled up from the upper opening of the filter head together with the element plate. Therefore, there is an effect that the filter element can be easily attached and detached.
[0033]
According to claim 2, by providing the relief port and the relief valve for protecting the element on the side wall of the filter head, when replacing the filter element, only the filter element can be taken out regardless of the relief valve. There is an effect that it is possible to reduce the size of the component and the cost of the component.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of a hydraulic system return filter device according to a first embodiment of the present invention.
FIG. 2 is a longitudinal side view of a conventional return filter device for a hydraulic system.
[Explanation of symbols]
21 ... Filter head 22 ... Oil inlet 27 ... Filter case 30 ... Bottom 31 ... Oil outlet 32 ... Filter element 33 ... Filter member 34 ... Filter plate 36 ... Opening 38 ... Seal member 40 ... Relief port 44 ... Relief valve 45 ... coil spring

Claims (1)

A filter head having an oil inlet on the peripheral side wall and having an upper opening and a lower opening facing each other in the upper and lower parts;
A cover provided at the upper opening of the filter head so as to be openable and closable;
A filter case having an upper end opening connected to the lower opening of the filter head, communicating with the inside of the filter head, and having an oil outlet.
In the state where the filter case is supported at the bottom of the filter case, the oil that is detachably provided and flows in from the oil inlet is allowed to pass from the inside to the outside to be discharged from the oil outlet. A cylindrical filter element with an upper opening for capturing the contained foreign matter,
The filter element is fixed to the filter head and has an opening facing the lower opening of the filter head, and the outer peripheral portion includes an inner peripheral portion of the filter head and an element plate sealed in a liquid-tight manner by a seal member,
A relief port that bypasses the opening of the element plate and communicates with the outside of the filter element is provided on a side wall of the filter head, and a relief valve for protecting the element is provided on the relief port, and the relief port and the relief valve are provided on the filter head. Retract outside the upper and lower openings,
The return filter device for a hydraulic system, wherein the filter element is detachable from the upper opening of the filter head together with the element plate.

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