JPH10328512A - Filter with foreign matter sensor function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter with a sensor function by which metal foreign matter can be caught and capable of informing of the presence of the metal foreign matter in an oil path. SOLUTION: A filter with a sensor function 15 is constituted of a filer base material 40 consisting of nonconductive filaments 32 and conductive meshes 41 consisting of conductive filaments 33a, 33b. The conductive filaments 33a, 33b are separated from each other and arranged on the filter base material 40 in a parallel state to each other. The conductive filaments 33a, 33b are exposed to the surface of the filter base material 40. When voltage is applied to between the conductive filaments 33a, 33b and to which metal foreign matter M is stuck, a short circuit is made between the conductive filaments 33, 33b and an electric current flows so that an indicator 50 is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter having a foreign matter sensor function for removing metallic foreign matter mixed in a hydraulic system.

[0002]

2. Description of the Related Art In a hydraulic system in which a hydraulic device is operated by hydraulic pressure, if foreign matters such as metal particles are mixed in the system, various problems such as malfunction or damage of the hydraulic device occur. A foreign substance is removed by providing a filter to the filter. In particular, if a relatively large metal foreign matter exceeding several tens of μm is caught in a sliding portion of a hydraulic device, it may cause a large trouble such as inoperability or breakage of the device. It is an important task to remove large metal foreign matter. Such metallic foreign matter often occurs immediately after delivery of the hydraulic system, that is, when a new hydraulic system is started to operate, or when hydraulic equipment is damaged for some reason.

[0003]

Conventionally, in order to remove the above-mentioned metallic foreign matter, a filter having a coarse mesh is provided in an oil passage from a hydraulic pump to a hydraulic device such as an actuator. To be sent to Such a filter merely has a function of capturing foreign matter, and does not have a function of notifying the presence of metallic foreign matter. However, if a hydraulic system having an abnormality that causes metal foreign matter is left as it is, the entire system including the hydraulic equipment may be seriously affected. It is an object of the present invention to provide a filter with a sensor function capable of catching a foreign substance and promptly notifying that a metallic foreign matter is present in an oil passage.

[0004]

According to a first aspect of the present invention, there is provided a filter according to the present invention, comprising: a filter substrate having a gap made of a non-conductive material through which hydraulic oil passes; A conductive mesh in which a plurality of conductive filaments are provided apart from each other in parallel and exposed on the surface of the filter substrate, and a voltage is applied between the conductive filaments adjacent to each other; and The display device is characterized by electrically short-circuiting the conductive filaments adjacent to each other when a metal foreign matter is attached, thereby causing a current to flow to operate the display. This filter is provided at a position where the entire amount of hydraulic oil in the hydraulic circuit passes.

[0005] The filter of the present invention is formed into a shape as required, such as a circle, an oval, a square, a polygon, and the like. The distance between the conductive filaments adjacent to each other is preferably 25 μm or more, particularly preferably 50 μm or more, for removing relatively large foreign matter. The material of the conductive filament is iron-based metal,
Metals such as copper and aluminum, and conductive materials such as carbon fiber. As the material of the non-conductive filament, for example, a synthetic resin such as polyester, polyamide, fluororesin, and aramid, or an inorganic material such as glass is suitable.

[0006] Both the conductive filament and the non-conductive filament may be in the form of a monofilament or a multifilament. Conductive filament and non-conductive filament constituting the filter of the present invention,
For example, a conductive filament and a non-conductive filament may be woven vertically and horizontally, such as a weft and a warp in a plain weave, or a non-conductive filament in a first direction and a conductive filament in a second direction may be used. The reticulated body may be formed by overlapping and fusing the intersections of both. Further, a non-conductive filament functioning as an insulating spacer may be arranged between the conductive filaments adjacent to each other.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The hydraulic system 10 illustrated in FIG. 2 includes a hydraulic pump 12 as a hydraulic pressure source for driving a hydraulic device 11 such as an actuator.
The hydraulic pump 12 sucks the working oil stored in the oil tank 13 through a suction filter 14 such as a strainer, and passes through a filter 15 on the discharge side and a pressure oil passage 16,
The power is supplied to a hydraulic device 11 such as a hydraulic actuator. A well-known relief valve 17 is connected to the pressure oil passage 16. A filter 19 is also provided in the return oil passage 18 of the hydraulic device 11.

As shown in FIG. 1, the filter 15 includes a frame member 30 made of a non-conductive material such as synthetic resin and paper, and a filter element 31 held by the frame member 30. The shape of the filter 15 is circular, oval or square. It is a polygon and the like, and is made into a shape as required.

The filter element 31 includes a plurality of non-conductive filaments 32 corresponding to warp extending in the vertical direction in FIG. 1, a plurality of conductive filaments 33a and 33b corresponding to weft extending in the left-right direction, and a non-conductive material. Is woven as if it were a plain weave structure. Between the filaments 32, 33a, 33b and 34, mesh-shaped mesh-like voids 35 through which hydraulic oil can freely pass are formed.

The material of the non-conductive filament 32 is a non-conductive material such as a synthetic resin such as polyester, polyamide, fluororesin and aramid, or an inorganic material such as glass. These many non-conductive filaments 3
2 are woven so as to be separated from each other in parallel, and constitute a filter substrate 40 referred to in this specification.

The filter substrate 40 may be in the form of a woven or knitted structure other than a plain weave, or may be in the form of a non-woven fabric or a net-like material, that is, a mesh-like space through which hydraulic oil can pass. 35 is sufficient. In the above embodiment, the non-conductive filament 32 and the conductive filaments 33a, 33b intersect at right angles to each other. However, in some cases, the non-conductive filament 32, 33a, 33b intersects at an angle other than a right angle. You may.

The material of the conductive filaments 33a and 33b is, for example, a metal such as iron, copper, aluminum and stainless steel, or a conductive substance such as carbon fiber. In FIG. 1, the conductive filaments 33a and 33b are indicated by hatching for easy understanding. The conductive filaments 33a and 33b are woven so as to be adjacent to each other alternately and in parallel and separated from each other. The distance (pitch: P) between the conductive filaments 33a and 33b is preferably 25 μm or more (for example, about 50 μm or more) in order to detect a relatively large metal foreign matter. A conductive mesh 41 is formed by the conductive filaments 33a and 33b.

The conductive filaments 33a and 33b are exposed on the surface of the filter substrate 40, so that the hydraulic oil flowing in the oil passage can touch the conductive filaments 33a and 33b. Each of the non-conductive filament 32 and the conductive filaments 33a and 33b may be in the form of a monofilament or a multifilament.

In this embodiment, a spacer filament 34 made of a non-conductive material is inserted between the conductive filaments 33a and 33b, and an appropriate distance is maintained between the conductive filaments 33a and 33b by the spacer filament 34. In addition, an electrical short circuit caused by contact between the conductive filaments 33a and 33b is reliably avoided.

The first conductive filament 33a is connected to the first lead wire 45, and the second conductive filament 3a
3b is connected to the second lead wire 46. The first lead wire 45 is connected to one electrode 52 of a power supply (DC power supply in the illustrated example) 51 via a display 50. An example of the display 50 is a display lamp or an alarm device, which is activated when a current flows. The second lead wire 46 is connected to the other electrode 53 of the power supply 51.
A voltage is applied between the conductive filaments 33a and 33b adjacent to each other by the power supply 51.

When the filter 15 having the above structure is provided in the oil passage, if the metal foreign matter M present in the oil passage is larger than the gap 35, the metal foreign matter M is captured by the conductive mesh 41. When the outer shape of the metal foreign matter M is larger than the distance between the conductive filaments 33a and 33b (for example, 50 μm), the metal foreign matter M comes into contact with the first conductive filament 33a and the second conductive filament 33b at the same time.

The metallic foreign matter M includes iron-based metal, aluminum,
It is a fine metal piece or metal particle such as various metals and alloys including copper, and has electrical conductivity,
When the conductive filaments 33a and 33b come into contact with each other, the conductive filaments 33a and 33b are electrically short-circuited, and current flows through the lead wires 45 and 46. As a result, the display 50 operates. The display 50 is provided at a position where an operator or the like who operates and manages the hydraulic system 10 can monitor with the five senses. Therefore, it is possible to immediately know that the metallic foreign matter M is captured by the filter 15.

As shown in FIG. 3, conductive filaments 33a, 3 extending in the second direction (lateral direction) are provided on the surface of the non-conductive filament 32 extending in the first direction (vertical direction).
The mesh may be formed by alternately arranging the spacers 3b and, if necessary, the spacer filaments 34, and fusing or bonding the intersections of the filaments 32, 33a, 33b, 34. The fusion in this case can be performed by high-frequency induction heating or the like, and the material of the non-conductive filament 32 is suitably a thermoplastic resin. Further, the present invention may be applied to a suction filter 14 such as a strainer or a low pressure side filter 19 provided in a return oil passage 18.

[0019]

According to the first aspect of the present invention, it is possible to catch relatively large metallic foreign matter in the oil passage, prevent the metallic foreign matter from circulating in the hydraulic system, and reduce the hydraulic pressure. The presence of metal foreign matter in the system can be promptly notified, and the soundness of the hydraulic system can be ensured. Further, according to the configuration described in claim 2, in addition to the effect of claim 1, since a weaving technique such as plain weaving can be used for the manufacture of the filter, the filter with the sensor function can be easily manufactured. According to the configuration of the third aspect, in addition to the effects of the first and second aspects, a short circuit due to the conductive filaments contacting each other can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a plan view of a filter with a sensor function according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing an example of a hydraulic system.

FIG. 3 is a plan view of a filter with a sensor function according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Hydraulic system 15 ... Filter 32 ... Non-conductive filament 33a, 33b ... Conductive filament 34 ... Spacer filament 40 ... Filter base material 41 ... Conductive mesh 50 ... Display

Claims (3)

[Claims] 1. A filter base made of a non-conductive material and having a gap through which hydraulic oil passes, and a plurality of conductive filaments provided apart from each other in parallel and exposed on the surface of the filter base, and A conductive mesh to which a voltage is applied between the conductive filaments adjacent to each other, and when a metal foreign matter adheres to the conductive mesh, a current is caused to flow by electrically short-circuiting the conductive filaments adjacent to each other. A filter with a foreign matter sensor function characterized by actuating a display. 2. The filter substrate according to claim 1, wherein said filter substrate is constituted by a plurality of mutually non-conductive filaments extending in a first direction, and said conductive mesh extends in a second direction intersecting said non-conductive filaments. 2. The filter according to claim 1, wherein the filter has a woven tissue structure constituted by conductive filaments. 3. The filter according to claim 2, wherein a non-conductive filament as a spacer is disposed between said conductive filaments adjacent to each other.