JP6221998B2 - filter - Google Patents

Description

  The present invention relates to a filter for capturing foreign matter in a fluid.

  Conventionally, as this type of filter, for example, there is one described in Patent Document 1. The filter described in Patent Document 1 has a cylindrical shape with a bottom, and a large-diameter cylindrical portion on the opening end side serving as a fluid inlet is fixed to the fluid passage hole, and has a smaller diameter than the large-diameter cylindrical portion. The small-diameter cylindrical portion is disposed on the downstream side of the large-diameter cylindrical portion, and the large-diameter cylindrical portion and the small-diameter cylindrical portion are connected by the connecting cylindrical portion. The small-diameter cylindrical portion is provided with a large number of small-diameter cylindrical portion holes as filtration holes along the axial direction and the circumferential direction of the small-diameter cylindrical portion.

JP 2004-122100 A

  By the way, in the conventional filter described above, a cylindrical gap (hereinafter referred to as a first annular gap) is formed between the small-diameter cylindrical portion and the fluid passage hole wall surface, and between the connecting cylinder portion and the fluid passage hole wall surface. A cylindrical gap (hereinafter referred to as a second annular gap) is formed, and the fuel that has flowed into the large diameter cylindrical portion flows into the first annular gap through the small diameter cylindrical portion hole, and further passes through the first annular gap. Flowing downstream.

  That is, since the fluid does not flow in the vicinity of the second annular gap, it can be regarded as a closed tube. More specifically, in the vicinity of the second annular gap, the closed end on the large-diameter cylinder portion side in the second annular gap is a fixed end, and on the other hand, the position of the small-diameter cylinder hole closest to the second annular gap in the first annular gap. Can be regarded as a closed tube.

  When a pressure wave (sound wave) having a specific frequency (the natural frequency of the fluid in the closed tube) is input to the closed tube portion that can be regarded as such a closed tube, the fluid staying in the closed tube portion resonates. As a result, pressure pulsation may occur, causing vibration and noise.

  In view of the above points, an object of the present invention is to suppress vibration and noise caused by pressure pulsation in a closed tube portion of a filter installation portion.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a bottomed cylindrical filter that is installed in a fluid passage hole (11) through which a fluid flows and captures foreign matters in the fluid. A large-diameter cylindrical portion (31) on the opening end side that serves as an inlet portion for fluid, and a small-diameter cylindrical portion (32) that is disposed downstream of the large-diameter cylindrical portion and has a smaller diameter than the large-diameter cylindrical portion. A diameter of the large-diameter cylindrical portion is reduced toward the small-diameter cylindrical portion, and a connecting cylindrical portion (33) that connects the large-diameter cylindrical portion and the small-diameter cylindrical portion; A plurality of small-diameter cylindrical hole (34) that allows communication between the peripheral side and the outer peripheral side, and a connecting cylindrical part hole (35) that is formed in the connecting cylindrical part and allows communication between the inner peripheral side and the outer peripheral side of the connecting cylindrical part. It is characterized by providing.

  By the way, the natural frequency of the fluid in the closed tube portion is inversely proportional to the distance between the fixed end and the free end. If the energy of the pressure wave input to the closed tube is the same, the amplitude of the pressure pulsation generated by resonance decreases as the natural frequency of the fluid in the closed tube increases.

  And in invention of Claim 1, by providing a connection cylinder part hole in a connection cylinder part, since the position of this connection cylinder part hole serves as a free end, since the distance of a free end and a fixed end becomes shorter than before, The natural frequency of the fluid in the closed tube portion is increased. Accordingly, if the energy of the pressure wave input to the closed tube portion is the same, the amplitude of the pressure pulsation is reduced, and as a result, vibration and noise due to the pressure pulsation in the closed tube portion of the filter installation portion can be suppressed.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a figure which shows a fuel injection valve provided with the filter which concerns on one Embodiment of this invention in a partial cross section. It is a figure which expands and shows the filter installation part in FIG. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG.

  An embodiment of the present invention will be described.

  The filter of the present invention is applied to, for example, a fuel injection valve of a diesel engine (not shown). As shown in FIG. 1, in the fuel injection valve, a nozzle 2 and a filter 3 are assembled to a body 1, high-pressure fuel supplied from a common rail (not shown) passes through the filter 3, reaches the nozzle 2, and the nozzle 2 opens. When the valve is operated, fuel is injected into the combustion chamber.

  As shown in FIG. 2, the body 1 is formed with a fluid passage hole 11 through which high-pressure fuel supplied from the common rail flows. A filter 3 that captures foreign matter in the fuel is installed at the most upstream portion of the fluid passage hole 11.

  The filter 3 is made of a metal material (for example, stainless steel), and is formed into a bottomed cylindrical shape by cold forging or the like. Further, the filter 3 is disposed on the downstream side of the fuel flow with respect to the large-diameter cylindrical portion 31 on the opening end side serving as the fuel inlet portion, and on the downstream side with respect to the large-diameter cylindrical portion 31, and the large-diameter cylindrical portion is closed. A small-diameter cylindrical portion 32 having a smaller diameter than the portion 31, and a connecting cylindrical portion 33 that reduces the diameter from the large-diameter cylindrical portion 31 toward the small-diameter cylindrical portion 32 and connects the large-diameter cylindrical portion 31 and the small-diameter cylindrical portion 32. I have. The large-diameter cylinder part 31, the small-diameter cylinder part 32, and the connecting cylinder part 33 are arranged coaxially.

  The filter 3 is fixed by press-fitting the large-diameter cylindrical portion 31 into the fluid passage hole 11. A cylindrical gap (hereinafter referred to as an annular gap) 4 is formed between the wall surface of the fluid passage hole 11 and the small diameter cylindrical portion 32 and the connecting cylindrical portion 33.

  The small-diameter cylindrical portion 32 is formed with a plurality of small-diameter cylindrical portion holes 34 that allow the inner peripheral side and the outer peripheral side of the small-diameter cylindrical portion 32 to communicate with each other. The small-diameter cylindrical hole 34 is set to have an inner diameter smaller than a foreign substance to be captured, and functions as a filtration hole for capturing the foreign substance in the fuel. Further, a plurality of small diameter cylindrical portion holes 34 are arranged along the axial direction of the small diameter cylindrical portion 32, and a plurality of small diameter cylindrical portion holes 34 are arranged at intervals of 30 ° along the circumferential direction of the small diameter cylindrical portion 32 as shown in FIG. Yes.

  The connecting cylinder part 33 is formed with a connecting cylinder part hole 35 for communicating the inner peripheral side and the outer peripheral side of the connecting cylinder part 33. The connecting cylinder part hole 35 is set to have an inner diameter smaller than a foreign substance to be captured, and functions as a filtration hole for capturing the foreign substance in the fuel. Further, only one row of the connecting cylinder part holes 35 is arranged in the axial direction of the connecting cylinder part 33, and a plurality of connecting cylinder part holes 35 are arranged at intervals of 90 ° along the circumferential direction of the connecting cylinder part 33 as shown in FIG. .

  Here, since a relatively large stress is generated in the connecting cylinder portion 33 due to stress concentration, if the number of the connecting cylinder portion holes 35 is increased excessively, there is a risk of damage due to insufficient strength.

  Therefore, from the viewpoint of maintaining the strength of the connecting cylinder portion 33, the following is performed. First, the diameter of the connecting cylinder part hole 35 is set to be equal to or smaller than the diameter of the small diameter cylinder part hole 34. Further, the number of the connecting cylinder part holes 35 is as small as possible (at least one, four in this example). Further, the circumferential pitch of the connecting cylinder hole 35 is set to be equal to or greater than the circumferential pitch of the small diameter cylinder hole 34. Furthermore, the small diameter cylinder hole 34 is provided at a position away from the connecting cylinder hole 35. Specifically, the filter axial distance between the small-diameter cylindrical hole 34 and the coupling cylindrical hole 35 located closest to the connecting cylindrical hole 35 is set to be equal to or greater than the filter axial distance between adjacent small-diameter cylindrical holes 34. Yes.

  In the above configuration, the high-pressure fuel supplied from the common rail to the fluid passage hole 11 flows into the filter 3 from the opening of the large-diameter cylindrical portion 31, and then passes through the small-diameter cylindrical portion hole 34 and the connecting cylindrical portion hole 35. It flows into the annular gap 4 and further flows downstream through the annular gap 4. Further, foreign matters in the fuel larger than the small diameter cylindrical portion hole 34 and the connecting cylindrical portion hole 35 cannot pass through the small diameter cylindrical portion hole 34 and the connecting cylindrical portion hole 35 and are captured in the filter 3.

  Here, a portion of the annular gap 4 that is closer to the larger-diameter cylindrical portion 31 than the connecting cylindrical portion hole 35 (hereinafter referred to as a closed pipe portion of the annular gap 4) can be regarded as a closed pipe because fuel does not flow therethrough. In other words, the position of the connecting tube portion hole 35 becomes the free end of the closed tube portion of the annular gap 4.

  And since the connection cylinder part hole 35 is located in the fixed end side of the closed pipe part of the annular gap 4 rather than the small diameter cylinder part hole 34, the length of the closed pipe part of the annular gap 4 does not have the connection cylinder part hole 35. It becomes shorter than the length of the closed tube portion of the annular gap in the conventional filter.

  Therefore, if the natural frequency of the fuel staying in the closed tube portion of the annular gap 4 is increased and the energy of the pressure wave input to the closed tube portion of the annular gap 4 is the same, the amplitude of the pressure pulsation is reduced. Vibration and noise due to pressure pulsation in the closed tube portion of the annular gap 4 are suppressed.

As described above, according to the present embodiment, by providing the connecting cylinder part hole 35, the natural frequency of the fuel staying in the closed pipe part of the annular gap 4 is increased, and the closed pipe part of the annular gap 4 is Further, the vibration and noise due to the pressure pulsation can be suppressed. The diameter of the connecting cylinder part hole 35 can be made smaller than the diameter of the small diameter cylinder part hole 34, the number of connecting cylinder part holes 35 can be reduced, or the connecting cylinder part hole 35 can be reduced. By making the circumferential pitch of 35 equal to or greater than the circumferential pitch of the small diameter cylindrical hole 34, or by providing the small diameter cylindrical hole 34 at a position away from the coupling cylindrical hole 35, the strength of the coupling cylindrical part 33 can be maintained. .

(Other embodiments)
In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably.

  Further, in the above-described embodiment, it is needless to say that elements constituting the embodiment are not necessarily indispensable except for the case where it is clearly indicated that the element is essential and the case where the element is clearly considered to be essential in principle. .

  Further, in the above embodiment, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is particularly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to a specific number except for cases.

  In the above embodiment, when referring to the shape, positional relationship, etc. of components, the shape, position, etc., unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to relationships.

DESCRIPTION OF SYMBOLS 11 Fluid passage hole 31 Large diameter cylinder part 32 Small diameter cylinder part 33 Connection cylinder part 34 Small diameter cylinder part hole 35 Connection cylinder part hole

Claims (4)

A bottomed cylindrical filter that is installed in a fluid passage hole (11) through which a fluid flows and captures foreign matter in the fluid,
A large-diameter cylindrical portion (31) on the opening end side that is fixed to the fluid passage hole and serves as an inlet portion of the fluid;
A small-diameter cylindrical portion (32) disposed downstream of the large-diameter cylindrical portion and having a smaller diameter than the large-diameter cylindrical portion;
A connecting cylinder part (33) for reducing the diameter from the large diameter cylinder part toward the small diameter cylinder part and connecting the large diameter cylinder part and the small diameter cylinder part;
A plurality of small-diameter cylinder holes (34) formed in the small-diameter cylinder and communicating the inner peripheral side and the outer peripheral side of the small-diameter cylinder;
A filter, comprising: a connecting cylinder part hole (35) formed in the connecting cylinder part and communicating the inner peripheral side and the outer peripheral side of the connecting cylinder part.   The filter according to claim 1, wherein a hole diameter of the connecting cylinder part hole is equal to or smaller than a hole diameter of the small diameter cylinder part hole. A plurality of the small diameter cylindrical portion holes are provided along the circumferential direction,
A plurality of the connecting cylinder part holes are provided along the circumferential direction,
The filter according to claim 1 or 2, wherein a circumferential pitch of the connecting cylindrical hole is equal to or greater than a circumferential pitch of the small diameter cylindrical hole.   A filter axial direction distance between the small diameter cylindrical part hole and the connecting cylindrical part hole located closest to the connecting cylindrical part hole is equal to or greater than a filter axial distance between adjacent small diameter cylindrical part holes. The filter according to any one of claims 1 to 3.

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