JP4157813B2 - Automatic air bleeder for diesel engine - Google Patents

Description

  The present invention relates to an automatic air venting device for extracting air mixed in a fuel system of a diesel engine out of the system.

  FIG. 10 shows an example of a general fuel system of a conventional diesel engine. The fuel supply line 6 guides fuel from the fuel tank 1 to the injection pump 5 through the cementer 2, the feed pump 3, and the fuel filter 4, and An injection line 8 for introducing fuel from the injection pump 5 to each injection nozzle 7 attached to a cylinder head (not shown), and surplus fuel from each injection nozzle 7 is collected at the discharge point of the overflow valve 10 of the injection pump 5. A leakage line 9 and a fuel return line 11 for returning the fuel from the overflow valve 10 of the injection pump 5 to the fuel tank 1 are provided. When the diesel engine is started, the fuel in the fuel tank 1 is fed to the feed pump 3. The water in the fuel is removed by the sedimentator 2 After being filtered, the fuel is filtered by the fuel filter 4 through the feed pump 3, and then is pumped from the injection pump 5 to each injection nozzle 7, adjusted by each injection nozzle 7, and then injected into the combustion chamber. It is like that.

  The injection pump 5 is provided with an overflow valve 10 that regulates the pressure of the fuel supplied to itself to a predetermined value. When the fuel pressure exceeds a predetermined value, the overflow valve 10 opens and the fuel is supplied. Is returned to the fuel tank 1.

  In a diesel engine equipped with such a fuel system, air is mixed into the fuel system due to running out of fuel, replacement of the fuel filter 4, etc., and fuel is supplied to the injection pump 5 by the feed pump 3 for this mixed air. Therefore, there is a possibility that the diesel engine will not start stably and a start failure of the diesel engine may occur. Therefore, an automatic air bleeding pump 12 is provided in parallel to the feed pump 3.

  That is, if this automatic air bleed pump 12 is provided and the automatic air bleed pump 12 is driven by a battery before starting the diesel engine, the fuel passes through the automatic air bleed pump 12 without going through the feed pump 3. The pump is pumped by the flow, and the overflow valve 10 of the injection pump 5 is opened by the discharge pressure of the automatic air bleeding pump 12, and the fuel is forcibly sent to the fuel tank 1 together with the mixed air to remove the air from the fuel system. Will be.

  Then, after the air bleed pump 12 is driven for about 30 seconds to complete air bleed, the drive of the automatic air bleed pump 12 is stopped and the diesel engine is started. The fuel sucked up by the feed pump 3 via 2 is sent to the injection pump 5 through the fuel filter 4, so that a starting failure due to mixed air is avoided.

As prior art document information related to this type of automatic air venting device for diesel engines, there are the following Patent Document 1 and Patent Document 2 by the same applicant as the present invention.
JP-A-2-256869 Japanese Utility Model Publication No. 3-118268

  However, in the system in which air is released from the overflow valve 10 of the injection pump 5 by the automatic air bleed pump 12 as described above, a high performance automatic air bleed pump 12 capable of exhibiting a high discharge pressure sufficient to open the overflow valve 10. There is a problem that the equipment cost is high.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an automatic air bleeding device for a diesel engine that can remove mixed air from a fuel system at a lower cost than conventional equipment.

  The present invention is an automatic air bleeder for extracting air mixed in a fuel system of a diesel engine out of the system, and automatically bleeds a feed pump for sending fuel from a fuel tank to an injection pump through a fuel supply line. Equipped with a pump in parallel, the joint portion at the end of the fuel supply line is fastened to the fuel inlet portion of the injection pump, and the fuel is led from the joint portion to the internal communication flow path through the oil supply hole. An air vent hole for the communication flow path is provided above the joint bolt that is fed into the injection pump, and a valve seat is provided between the air vent hole side and the oil filler hole side when a backflow of fuel occurs from the air vent hole side. A backflow prevention stopper that blocks the communication channel by landing is installed so that the specific gravity is greater than that of the fuel and can be lifted from the valve seat only by air buoyancy. Another joint part is stacked on the upper part of the joint part so as to enclose the hole, and is fastened together with the joint bolt, and fuel is supplied to the fuel tank from the another joint part on the upper side and the overflow valve of the injection pump. The fuel return line is connected to the returning fuel return line by an air vent line.

  Thus, in this way, when the automatic air bleed pump is driven by the battery drive before starting the diesel engine, the fuel is pumped by the flow through the automatic air bleed pump without going through the feed pump, The fuel led from the fuel tank through the fuel supply line to the injection pump enters the connection flow path in the joint bolt from the joint portion at the end of the fuel supply line, where the mixed air is separated upward due to the specific gravity difference. The air is extracted from the air vent hole to the fuel return line through the upper joint portion and the air vent line, and the mixed air is removed from the fuel system together with the fuel returned to the fuel tank via the fuel return line. .

  In addition, a reverse flow prevention stopper that prevents the reverse flow of fuel from the air vent hole side is provided inside the joint bolt at the fuel inlet of the injection pump, so clogging occurs in the fuel filter etc. in the middle of the fuel supply line. Even when it becomes difficult for the injection pump to suck the fuel, the possibility that the fuel flows backward from the fuel return line via the air vent line and is guided to the injection pump is avoided.

  According to the automatic air venting device for a diesel engine of the present invention described above, various excellent effects as described below can be obtained.

  (I) Since the mixed air is separated by the specific gravity difference in the connecting flow path in the joint bolt at the fuel inlet of the injection pump and extracted to the fuel return line, the injection pump overflow valve is opened in the automatic air release pump. It is not necessary to require a high discharge pressure as much as possible, and even with an automatic air bleeding pump with a lower discharge pressure than before, mixed air can be sufficiently removed, and start-up failures due to the mixed air can be avoided in advance. Therefore, the performance of the automatic air bleed pump can be lowered compared with the conventional one, and the equipment cost can be greatly reduced.

  (II) Even when the fuel filter or the like in the middle of the fuel supply line is clogged and it becomes difficult for the injection pump to suck the fuel, the backflow prevention stopper in the joint bolt can prevent the backflow from the air vent line.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 5 show an example of an embodiment for carrying out the present invention, and portions denoted by the same reference numerals as those in FIG. 10 represent the same items.

  As shown in FIG. 1, in this embodiment, an automatic air bleeding pump 13 is provided for the feed pump 3 that sends fuel from the fuel tank 1 to the injection pump 5 through the fuel supply line 6 as in the conventional example of FIG. Although equipped in parallel, the automatic air vent pump 13 may not be required to have a high discharge pressure enough to open the overflow valve 10, and may have a performance lower than that of the conventional one.

  A joint bolt 15 as shown in FIGS. 2 to 4 is employed as a joint bolt 15 for fastening the joint portion 14 at the end of the fuel supply line 6 to the inlet portion of the injection pump 5. The joint portion 14 at the end of the fuel supply line 6 and another joint portion 16 on the upper stage side are stacked and fastened together.

  That is, this type of joint bolt 15 is conventionally employed at the end of various lines in the fuel system of a diesel engine. For example, a torus-like shape is provided at the end of the fuel supply line 6 as shown in the example. In addition, the joint portion 14 is fastened, and the fuel is led from the joint portion 14 through the oil supply hole 17 to the communication flow path 18 inside the joint portion 14 and fed into the injection pump 5. Here, however, an air vent hole 19 is separately drilled at a position above the oil supply hole 17 of the joint bolt 15, and the upper portion of the joint portion 14 is separately provided so as to enclose the air vent hole 19. The joint portions 16 are stacked.

  Here, regarding the aperture of the air vent hole 19, it is necessary to appropriately tune in consideration of the size of the diesel engine, the injection amount, and the like, but according to the verification experiment by the present inventor, the lubrication that is drilled in pairs In the case where each of the holes 17 is about 6.5 mm, it is confirmed that when the diameter of the air vent hole 19 is about 0.4 to 0.6 mm, a good air venting effect as described later can be obtained. .

  Further, in this embodiment, a backflow prevention stopper 27 for preventing a backflow from the air vent hole 19 side is provided inside the joint bolt 15 at the fuel inlet portion of the injection pump 5. In this case, a spherical backflow prevention stopper 27 having a specific gravity greater than that of the fuel and capable of rising from the valve seat only by air buoyancy is employed, and as shown in FIG. 4, the backflow of fuel from the air vent hole 19 side is prevented. When this occurs, the backflow prevention stopper 27 is landed on the valve seat 28 to block the communication flow path 18 between the air vent hole 19 side and the oil supply hole 17 side.

  On the other hand, with respect to the flow of fuel from the refueling hole 17 side to the air vent hole 19 of the normal communication flow path 18 as shown in FIG. 3, the backflow prevention stopper 27 easily floats from the valve seat 28 to air the fuel. It leaks into the joint portion 16 through the vent hole 19, and the backflow prevention stopper 27 can be easily pushed up by only the buoyancy of the air that floats from the lower side of the connecting flow path 18, and the air is removed from the air vent hole. 19 to be able to go.

  Further, the upper joint portion 16 in FIG. 1 is connected to the joint portion 20 of the fuel return line 11 fastened by the overflow valve 10 of the injection pump 5 via an air vent line 21.

  Here, the internal structure of the joint portion 20 of the fuel return line 11 and the overflow valve 10 is schematically shown in FIG. 5, and the overflow valve 10 presses the valve body 22 against the valve seat 24 by the elastic body 23. At least when the internal relief flow path 25 is closed and the fuel pressure in the injection pump 5 exceeds a predetermined value, the valve element 22 rises from the valve seat 24 against the elastic force of the elastic element 23. The fuel is leaked into the joint portion 20 through the oil discharge port 26.

  One end of the air vent line 21 is connected to the joint portion 20 of the fuel return line 11 so that fuel from the air vent line 21 overflows in the joint portion 20 regardless of whether the overflow valve 10 is opened or closed. It goes around the valve 10 and is guided to the fuel return line 11.

  Although not particularly shown in FIG. 5, the leakage lines 9 from the respective injection nozzles 7 are also connected to the joint portion 20 of the fuel return line 11.

  Thus, in this way, when the automatic air bleed pump 13 is driven by the battery drive before starting the diesel engine, the fuel flows through the automatic air bleed pump 13 without going through the feed pump 3. The fuel that is pumped and guided from the fuel tank 1 through the fuel supply line 6 to the injection pump 5 through the cementer 2, the feed pump 3, and the fuel filter 4 is supplied from the joint portion 14 at the end of the fuel supply line 6 to the joint bolt 15. The mixed air is separated to the upper side due to the difference in specific gravity, and from the air vent hole 19 to the fuel return line 11 through the upper joint portion 16, the air vent line 21, and the joint portion 20. The mixed air is removed from the fuel system together with the fuel extracted and returned to the fuel tank 1 via the fuel return line 11. Made.

  Therefore, according to the above embodiment, the mixed air is separated by the difference in specific gravity in the connecting flow path 18 in the joint bolt 15 at the fuel inlet of the injection pump 5 and is extracted to the fuel return line 11. It is not necessary to require the discharge pump 13 to have a high discharge pressure sufficient to open the overflow valve 10 of the injection pump 5, and even the automatic air release pump 13 having a lower discharge pressure than before can sufficiently remove the mixed air. The starting failure due to the mixed air can be avoided in advance, and the performance of the automatic air bleeding pump 13 can be lowered as compared with the prior art, and the equipment cost can be greatly reduced.

  Moreover, since a backflow prevention stopper 27 for preventing the backflow of fuel from the air vent hole 19 side is provided inside the joint bolt 15 at the fuel inlet portion of the injection pump 5, the fuel filter 4 in the middle of the fuel supply line 6, etc. Even when clogging occurs and it becomes difficult for the injection pump 5 to suck in the fuel, it is possible to avoid the possibility that the fuel flows backward from the fuel return line 11 through the air vent line 21 and is guided to the injection pump 5. it can.

  6 to 9 show modified examples of the backflow prevention stopper. In the example shown here, the backflow prevention of the T-shaped cross section in which the flange portion 30 is formed at the upper end of the cylindrical plug portion 29 is shown. A stopper 31 is employed, and a notch groove 32 (see FIGS. 8 and 9) extending in the vertical direction is formed on the outer peripheral surface of the plug portion 29 to devise a device for improving air bleeding.

  Even when such a backflow prevention stopper 31 is employed, the backflow prevention stopper 31 in the joint bolt 15 is used to remove the airflow from the air vent line 21 in the same manner as when the backflow prevention stopper 27 of FIGS. 3 and 4 is employed. Can prevent backflow.

  The automatic air venting device for a diesel engine according to the present invention is not limited to the above-described embodiment. In this embodiment, another joint portion on the upper side is connected to the joint portion of the fuel return line. However, it is needless to say that various modifications can be made within the scope of the present invention without departing from the gist of the present invention.

It is a systematic diagram which shows an example of the form which implements this invention. It is an external view of the joint bolt in the fuel inlet part of the injection pump of FIG. It is a fragmentary sectional view of FIG. It is sectional drawing which shows the flow-path obstruction | occlusion state by the backflow prevention stopper of FIG. It is sectional drawing of the overflow valve | bulb of FIG. It is sectional drawing which shows the modification of a backflow prevention stopper. It is sectional drawing which shows the flow-path obstruction | occlusion state by the backflow prevention stopper of FIG. It is an external view of the backflow prevention stopper of FIG. It is an arrow directional view of the IX-IX direction of FIG. It is a systematic diagram which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank 3 Feed pump 5 Injection pump 6 Fuel supply line 10 Overflow valve 11 Fuel return line 13 Automatic air vent pump 14 Joint part 15 Joint bolt 16 Joint part 18 Connection flow path 19 Air vent hole 21 Air vent line 27 Backflow prevention stopper 31 Backflow prevention stopper

Claims (1)

  An automatic air venting device for extracting air mixed in the fuel system of a diesel engine out of the system, and an automatic air venting pump in parallel with a feed pump for sending fuel from a fuel tank to an injection pump through a fuel supply line Equipped with a joint part at the end of the fuel supply line fastened to the fuel inlet part of the injection pump, and fuel is introduced into the connecting flow path through the oil supply hole into the injection pump. An air vent hole for the communication flow path is provided on the upper side of the joint bolt to be fed, and when a reverse flow of fuel from the air vent hole side occurs, the valve seat is seated between the air vent hole side and the oil supply hole side. Equipped inside the joint bolt with a backflow prevention stopper that closes the connecting flow path so that the specific gravity is greater than that of the fuel and the buoyancy of the air can lift the valve seat. In addition, another joint part is stacked on the upper part of the joint part so as to enclose the air vent hole, and is fastened together with the joint bolt. From the joint part on the upper stage side and the overflow valve of the injection pump, An automatic air bleeder for a diesel engine, wherein a fuel return line for returning fuel to a fuel tank is connected by an air bleed line.

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