JP2666271B2 - Centrifugal pre-cleaner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal pre-cleaner that captures and discharges dust contained in combustion air sucked into an engine combustion chamber by using centrifugal force. . [Prior art] A centrifugal precleaner includes guide vanes that generate a swirling flow in a duct through which combustion air flows, applies centrifugal force to dust contained in the swirling flow, and collects the dust around the outer periphery of the duct. To discharge. The conventional guide blade used in this centrifugal pre-cleaner has a central closing portion 101 having a central portion closed so that air flows in from the outer periphery of the guide blade 100, as shown in FIGS. 12 and 13. A plurality of fins 102 are provided around the central closing portion 101 and change the flow of air flowing into the duct to generate a swirling flow in the duct. [Problems to be Solved by the Invention] In the guide vane 100 described above, since the upstream side of the central closing part 101 is formed flat, the air supplied to the center part of the guide vane 100 is flat central closed The flow direction is largely changed by the part 101 and supplied to the outer fins 102. Therefore, the air passing through the guide vanes 100 is
, The flow direction is suddenly changed, so that there is a problem that the ventilation resistance when passing through the guide vane 100 is increased. Further, in the conventional fin 102, as shown in FIG. 14, since the direction of air flow is directly changed from the upstream of the fin 102, the boundary layer ( (Indicated by a broken line in the figure), the airflow resistance is increased, and a vortex is generated in the boundary layer downstream of the fins 102, thereby increasing the airflow resistance. Further, in the conventional fin 102, the inner circumference and the outer circumference are provided at a fixed angle, and the fin 102 on the inner circumference is provided with a shorter blade length that gives a swirling flow to air, compared to the outer circumference. Had been. Therefore, the inner circumference of the fin 102 has a problem that the efficiency of generating the swirling flow is low. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a centrifugal pre-cleaner capable of suppressing the airflow resistance when passing through a guide blade and improving the efficiency of generating a swirling flow by the guide blade. On offer. Means for Solving the Problems In order to achieve the above object, the present invention provides a duct having an inlet through which combustion air flows, an outlet communicating with an engine inlet, and a central part closed. A guide vane having a central closing portion, and having a plurality of fins around the central closing portion for changing a flow of air flowing into the duct to generate a swirl flow, downstream of the guide vane, and An upstream side is provided to be open at the center of the duct, and an inner cylinder that supplies air at a central portion of the swirling flow to the outlet, and is opened between an outer periphery of the inner cylinder and an inner periphery of the duct. And a closed end of the guide blade includes a conical portion protruding upstream, and the guide blade is provided upstream of a plurality of fins of the guide blade. Where the blades are housed Along the axial direction of the duct only, it extends to the upstream side of the slope of the conical portion in parallel with the airflow at the location, and further extends outward from the center of the conical portion and is connected to the fin. The provision of the guide is a technical measure. [Operation] The present invention forms a boundary layer along the guide from the upstream end of the guide by providing a guide in the axial direction of the duct upstream of the fins and parallel to the airflow flowing into the closing portion. . As a result, the boundary layer is formed smoothly along the fins from the guide, so that the air passing between the fins flows smoothly along the fins without being greatly affected by the boundary layer, and the flow direction is changed. Be changed. [Effects of the Invention] According to the present invention, since the air passing between the fins flows smoothly along the fins by the guides on the upstream side of the fins, the passage resistance of the air passing through the guide vanes is reduced. As a result, the generation efficiency of the swirling flow can be improved. Example Next, a centrifugal precleaner of the present invention will be described based on an example shown in the drawings. As shown in FIG. 2, the centrifugal precleaner 1 of the present embodiment includes an intake pipe 4 mounted on an air intake side of an air cleaner 3 that supplies clean combustion air to a combustion chamber of an engine 2, It is provided between air funnels 5 attached to the end of the intake pipe 4. This air funnel 5
Since it is provided at the upper end of the intake pipe 4 extending in the up-down direction, the inside communicating the suction port and the connection port of the precleaner 1 is bent at a right angle so that rainwater or the like does not enter the inside. This centrifugal pre-cleaner 1 is, as shown in FIG.
A duct 6 is provided between the upstream end of the intake pipe 4 and the air funnel 5. The duct 6 is made of a resin having a cylindrical shape, has an inlet 7 for supplying combustion air from the air funnel 5 into the duct 6 at the upstream end, and is ultrasonically welded to the air funnel 5. At the end connected to the intake pipe 4, an outlet 8 for supplying the air flowing into the duct 6 to the intake pipe 4 is provided, and the intake pipe 4 and the duct 6 are connected to a gasket 9 on a cylinder. Are connected by fitting. A large-diameter portion 10 having a diameter slightly larger than the inner diameter of the duct 6 is provided at an inner peripheral portion of the inlet 7 of the duct 6, and the large-diameter portion 10 has guide vanes 11 for generating a swirling flow in the duct 6. Is provided. As shown in FIGS. 3 to 5, the guide blade 11 has a cylindrical outer cylindrical portion mounted on the large-diameter portion 10.
12 and a central closing portion 13 provided at the center of the outer cylindrical portion 12 and closing the inner circumference. The central closing portion 13 guides the dust contained in the air to the outer peripheral side of the duct 6 and supplies the inner peripheral air to the outer periphery to improve the generation efficiency of the swirling flow. The central closing portion 13 includes a conical portion 14 having a central portion protruding in a substantially conical shape on the upstream side, and an outer peripheral cylindrical portion 12.
An inner peripheral tube portion 15 that is coaxial with the outer peripheral tube portion 12 is provided on the inner periphery of the inner tube. Fins that change the flow of air flowing into the duct 6 to generate a swirling flow are provided between the outer cylindrical portion 12 and the inner cylindrical portion 15.
Eightteen are provided at equal intervals. Fin of this embodiment
Reference numeral 16 has a spiral blade shape whose angle changes from the inner circumference to the outer circumference. Further, upstream of each fin 16, only along the axial direction of the duct 6 where the guide vanes 11 are accommodated, it extends to the upstream side of the slope of the conical portion 14 (the upper end of the conical portion 14 in this embodiment). ,
Guide 17 smoothly and continuously connected to fins 16
Is provided. The guide 17 is provided radially from the upstream end of the conical portion 14 to the outer peripheral end of the fin 16, and divides the air flowing between the fins 16 upstream of the fin 16, as shown in FIG. As shown in the figure, a boundary layer generated downstream from the upper end of the guide 17 (shown by a broken line in the figure)
Of the fins 16 by an air flow or the like flowing between the fins 16.
Are formed along. The boundary layer generated from the upper end of the guide 17 is a fin guide
It depends on the length of 17 and the diameter d (see FIG. 1) upstream of the guide vanes 11. Therefore, depending on the length of the fin guide 17 and the diameter d upstream of the guide blade 11, the guide blade
The effect of reducing the ventilation resistance when passing through 11 is different.
On the other hand, the length of the guide 17 according to the present embodiment changes according to the height h (length in the upstream direction) of the conical portion 14 (see FIG. 1). The solid line A in FIG. 7 shows the relationship between the ratio of the height h of the conical portion 14 to the diameter d upstream of the guide blade 11, and the effect of reducing the ventilation resistance. As shown in the graph of FIG. 7, the height h of the conical portion 14 / the diameter d upstream of the guide blade 11 exhibits a remarkable air flow resistance reducing effect between 1/20 to 3/5, At 1/5, the effect of reducing airflow resistance is almost maximum. When the relationship of height h / diameter d is larger than 1/5, the effect of reducing the airflow resistance decreases because the inside of the air funnel 5 upstream of the conical portion 14 is bent at a right angle. This is because, when the height h of the fourteen is higher than a predetermined value, the flow of air in the air funnel 5 is obstructed. The broken line B shown in the graph indicates the ventilation resistance value of the conventional guide blade. In addition, the outer peripheral cylindrical portion 12, the conical portion 14 of the central closing portion 13, the inner peripheral cylindrical portion 15, the fin 16, and the guide
11 is provided integrally with resin. On the other hand, an inner cylinder 18 having a cylindrical shape coaxial with the duct 6 is provided inside the downstream of the duct 6 in which the guide vanes 11 are provided on the upstream side.
Are provided integrally with the duct 6. The inner cylinder 18 supplies the air at the central portion of the swirling flow generated by the guide blade 11 to the intake pipe 4 through the outlet 8, and the upstream side of the inner cylinder 18 is located downstream of the guide blade 11, In addition, it is provided to be open at the center in the duct 6. Also, on the downstream side of the inner cylinder 18,
It is connected to the outlet 8 of the duct 6. A gap 19 is formed between the outer circumference of the inner cylinder 18 and the inner circumference of the duct 6 for collecting dust collected on the outer circumference of the duct 6 by centrifugal force due to the swirling flow. The duct 6 downstream of the gap 19 is provided with a duct outlet 20 opening into the gap 19. The duct outlet 20 is for taking out dust collected in the gap 19 to the outside of the duct 6, and a dust duct 21 is connected to the duct outlet 20. The mounting stay 22 provided on the outer periphery of the duct 6
Supports the centrifugal precleaner 1, the intake pipe 4, and the like, and is connected to members of the vehicle. Next, the operation of the centrifugal precleaner 1 will be described. When the engine 2 is started, combustion air is sucked into the combustion chamber during the suction process. Then, combustion air is supplied into the combustion chamber via the air cleaner 3, the intake pipe 4, the centrifugal pre-cleaner 1, and the air funnel 5. At this time, air containing dust is sucked in from the air funnel 5. The air sucked from the air funnel 5 passes through the guide blades 11 of the centrifugal precleaner 1. When air flows into the guide vanes 11, the air is divided into eight by the guides 17 and flows between the fins 16. At this time, the air supplied to the center of the guide blade 11
The conical portion 14 smoothly guides the outer peripheral fins 16.
Then, the air supplied to the outer periphery by the conical portion 14 from the inner periphery and the air supplied to the outer periphery from the air funnel 5 change the flow direction by flowing between the fins 16, and the swirl flows into the duct 6. It leaks out. On the other hand, when air flows into the guide vanes 11, as shown in FIG. 6, a boundary layer (broken line in the figure) is generated downstream from the upper end of the guide 17. Immediately after its onset, this boundary layer
Along the sides of the fins 16 as shown in the figure by the airflow flowing between each of the fins 16. Therefore, the air passing between each of the fins 16 is
Fins smoothly without being greatly affected by the boundary layer
Since the guide vanes 11 flow along the guide vanes 16, the airflow resistance of the guide vanes 11 of the present invention is reduced as compared with the conventional case, and the swirl flow generation efficiency can be improved. Further, in the present embodiment, the length of the fin 16 that applies the turning force to the air on the inner circumference is provided equal to the outer circumference, so that the air passing through the inner circumference is smoothly flowed by the fins 16 on the inner circumference, And since it is reliably changed, the generation efficiency of the swirling flow can be improved as compared with the conventional fin. The air that has passed through the guide vanes 11 forms a swirling flow in the duct 6. Among the dust contained in the swirling flow, a large amount of dust is collected on the outer peripheral side of the duct 6 by the action of the centrifugal force during the swirling. For this reason, in the air around the inner periphery of the duct 6, dust having a large mass is removed and flows into the inner cylinder 18,
The air is supplied to the air cleaner 3 through the intake pipe 4. Then, the air cleaner 3 removes fine dust that cannot be removed by the centrifugal pre-cleaner 1 and supplies the dust to the engine 2. On the other hand, the dust collected on the outer periphery of the duct 6 is collected in the gap 19 by the flow of air, and
Due to the intake pulsation that occurs during the intake of the duct, the duct outlet 20,
The dust is discharged from the dust duct 21 to the outside of the duct 6. 8 and 9 show a second embodiment of the present invention. In the present embodiment, the fins 16 and the guides 17 of the guide vanes 11 are provided in a spiral shape, and are designed to improve the generation efficiency of the swirling flow and the effect of reducing the ventilation resistance. FIG. 10 shows a third embodiment of the present invention. In the present embodiment, the centrifugal pre-cleaner 1 is provided downstream of the straight intake pipe 4, and the ratio of the height h of the conical portion 14 to the diameter d of the intake pipe 4 and the reduction of the ventilation resistance are reduced. The relationship between the effects is shown by the solid line C in the graph of FIG. As shown in this graph, the height h of the conical portion 14 / the diameter d upstream of the guide blade 11 exhibits a remarkable air flow resistance reducing effect at 1/20 or more,
If it exceeds 4, the effect will increase gradually. The broken line B shown in the graph indicates the ventilation resistance value of the conventional guide blade. In the present embodiment, the length of the guides of the outer fins is set short. However, the present invention is not limited to this embodiment, and the lengths of the inner and outer guides may be the same, or The outer peripheral guide may be provided with a longer length. Further, in this embodiment, the duct and the guide blade are provided separately, but may be provided integrally. Further, although the duct and the inner cylinder are provided integrally, they may be provided separately.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view of a centrifugal pre-cleaner, FIG. 2 is a schematic view of a vehicle showing a mounting position of the centrifugal pre-cleaner, FIG. The figure is a top view of the guide vane,
FIG. 5 is a sectional view taken along the line II shown in FIG. 4, FIG. 6 is an explanatory view showing the flow of air near the fins and the guide, and FIG. FIG. 8 is a graph showing the relationship between the ratio to the diameter and the effect of reducing the ventilation resistance, FIG. 8 is a top view of a guide blade showing a second embodiment of the present invention, and FIG. FIG. 10 is a side sectional view of a centrifugal pre-cleaner showing a third embodiment of the present invention, and FIG.
FIG. 12 is a graph showing the relationship between the ratio of the height of the conical portion 14 to the diameter of the upstream of the guide blade and the effect of reducing the air flow resistance in the third embodiment. FIGS. 12 and 13 are top views of the conventional guide blade and FIGS. FIG. 14 is a side sectional view, and is an explanatory view showing the flow of air near the fins of the conventional guide blade. In the figure, 1 ... centrifugal pre-cleaner, 2 ... engine, 6
... duct, 7 ... inlet, 8 ... outlet, 11 ... guide vane, 13 ... central closing part, 14 ... conical part, 16 ... fin, 17 ... guide, 18 ... inner cylinder , 20 ... Dust outlet

   ────────────────────────────────────────────────── ─── Continuation of front page    (56) References Japanese Utility Model Showa 58-191371 (JP, U)                 Shokai Sho 57-99717 (JP, U)                 52-6044 (JP, Y2)

Claims (1)

(57) [Claims] A duct having an inflow port through which combustion air flows in and an outflow port communicating with the engine intake port; a central closing portion closing a central portion, and air flowing into the duct around the central closing portion. A plurality of fins that generate a swirling flow by changing the flow of the swirling flow, and a downstream side of the guide blade and an upstream side are provided to be opened at a central portion of the duct, and a center portion of the swirling flow is provided. A centrifugal precleaner having an inner cylinder that supplies air to the outlet, and a dust outlet that is provided between the outer circumference of the inner cylinder and the inner circumference of the duct; The closing portion includes a conical portion protruding upstream, and upstream of the plurality of fins of the guide vane, only along the axial direction of the duct at a location for accommodating the guide vane, and the air flow at the location. In parallel A centrifugal pre-cleaner, wherein the fin is provided with a guide extending to an upstream side of a slope of the conical portion and further extending outward from a center of the conical portion. 2. The length of the conical portion in the upstream direction is 1/20 of the radial length of the upstream position of the guide blade when the flow direction of the air flow is changing at a substantially right angle immediately before the upstream of the guide blade. ~
The centrifugal pre-cleaner according to claim 1, wherein the pre-cleaner is provided between 3/5. 3. The length of the conical portion in the upstream direction is provided at least 1/20 of the radial length of the upstream position of the guide blade when the flow direction of the air flow is not changed immediately before the upstream of the guide blade. The centrifugal pre-cleaner according to claim 1, wherein the pre-cleaner is used. 4. The centrifugal precleaner according to any one of claims 1 to 3, wherein the fin, the conical portion, and the guide are provided integrally. 5. The centrifugal pre-press according to any one of claims 1 to 4, wherein the fin has a spiral blade shape whose angle changes from an inner circumference to an outer circumference. Cleaner.