JP4700708B2 - Fuel injection pump - Google Patents

Description

  The present invention relates to a fuel injection pump having a structure in which a plunger in a plunger barrel is moved up and down by a cam, and more particularly to a technique for returning lubricating oil that has entered the tappet to a gear case.

  Conventionally, a camshaft supported by a bearing in an engine housing (crankcase, gearcase, pump housing, etc.) is driven from a crankshaft through a gear, etc., and a plunger is reciprocated by rotation of a cam provided on the camshaft. Fuel injection pumps that increase the pressure of fuel oil by reciprocating movement of the plunger are known (for example, see Patent Document 1).

The plunger is supported by a plunger barrel so as to be slidable up and down. When the lower portion of the plunger is pressed upward by the cam via the tappet, the plunger moves upward and is formed above the plunger. The fuel oil in the fuel pressure chamber is compressed.
Further, in the pump housing below the plunger barrel, a cylindrical sliding hole is formed in the vertical direction to constitute a tappet chamber, and the tappet is slidably arranged in the tappet chamber. A space above the tappet (inside the tappet) is provided with a plunger spring that urges the plunger downward, a control sleeve for controlling the injection amount by rotating the plunger, and the like.

  In this conventional configuration, lubricating oil is supplied into a cam chamber formed in the housing, and the drive system components such as the cam and gears are lubricated by the lubricating oil. The lubricating oil in the cam chamber, the gear case, and the valve arm chamber returns to the crankcase through the circulation path, and is circulated by being pumped to the lubricating path by the lubricating oil pump.

  Further, in order to prevent the lubricating oil that has entered the tappet chamber from being mixed into the fuel oil along the sliding surface of the plunger, a communication passage that allows the tappet chamber and the gear case to communicate with the pump housing. In addition, a fuel injection pump having a configuration in which a communication passage that communicates the inner space of the tappet with the communication passage is known (see, for example, Patent Document 2).

Further, in order to prevent the lubricating oil that has entered the tappet chamber from entering the fuel oil through the sliding surface of the plunger, the pump housing is provided with a space inside the tappet and an internal space of the cam chamber. A fuel injection pump having a configuration in which a communication passage is provided therebetween is also known. However, in order to provide a communication path between the space inside the tappet and the internal space of the cam chamber, it is necessary to make a hole in the housing, which increases the cost and provides a space for providing the communication path. The fuel injection pump became large as needed.
Therefore, a technique for providing a vent hole in the tappet in order to prevent the pressure inside the tappet from being increased due to the reciprocating motion of the tappet and preventing the lubricating oil from being mixed into the fuel oil or leaking is known. .
JP 2003-254186 A JP 2005-146984 A

  However, in the conventional fuel injection pump, when the vent hole is provided in the tappet, the splash of lubricating oil splashed up from the cam chamber enters the space inside the tappet from the vent hole and enters the tappet chamber. There is a possibility that the infiltrated lubricating oil is scattered by the ascending of the tappet and mixed into the fuel oil along the sliding surface of the plunger.

  The lubricating oil that has entered the tappet chamber is recovered from the vent hole into the cam chamber. However, depending on the natural fall of the lubricating oil, there is a case where the lubricating oil cannot be sufficiently recovered. It was.

  Therefore, in view of such problems, the present invention provides a fuel injection pump that forcibly collects lubricating oil accumulated inside a tappet into a gear case.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, according to the first aspect of the present invention, the tappet is attached to the lower portion of the plunger, the cam is in contact with the lower surface of the tappet, and the cam is rotated to reciprocate the plunger to pump fuel oil. In the injection pump, a communication hole that communicates the tappet chamber that houses the tappet and the outside of the pump housing in which the tappet chamber is provided is provided, and suction means is connected to the communication hole.

  According to a second aspect of the present invention, an opening / closing valve is provided in a suction passage connecting the communication hole and the suction means, the opening / closing valve and the engine rotation detection means are connected to a control means, and the phase of the cam is detected by the engine rotation detection means. The opening / closing valve is controlled to open and close at a set phase.

  According to a third aspect of the present invention, the on-off valve is controlled to open when the phase is during the upward stroke of the plunger and the cam speed of the cam is greater than or equal to a set value.

  According to a fourth aspect of the present invention, the other end of the return passage connected to the discharge side of the suction means is connected to a gear case connected to the pump housing.

  According to a fifth aspect of the present invention, the connection position of the other end of the return passage is above the gear accommodated in the gear case.

  As effects of the present invention, the following effects can be obtained.

  In claim 1, by the suction means, out of the lubricating oil that has entered the tappet chamber, it is possible to suck the lubricating oil splashing in the tappet chamber and excess lubricating oil, and forcibly discharge the lubricating oil, It is possible to prevent the lubricating oil from adhering to the plunger and mixing into the fuel oil through the gap between the plunger and the plunger barrel. As a result, sulfides and the like contained in the exhaust gas can be reduced.

  In claim 2, since the suction of the lubricating oil by the suction means can be performed at the set phase, it can be efficiently sucked when many splashes of the lubricating oil are generated, and the excessive suction of the lubricating oil is prevented and seizure occurs. Can be prevented.

  According to the third aspect of the present invention, since the suction is performed only when the plunger is raised and the cam speed is equal to or higher than the predetermined value, the mixing of the lubricating oil into the fuel pressure chamber can be reduced, and the on-off valve is closed at the time of starting or at low speed rotation. Further, it is possible to prevent the plunger from being seized by preventing the excessive lubricating oil from being sucked. As a result, the fuel injection pump can be stably operated, and the durability of the fuel injection pump is improved.

  According to the fourth aspect of the present invention, the entire amount of the lubricating oil in the engine housing can be kept constant by returning the sucked lubricating oil to the gear case. Further, the internal pressure inside the engine housing can be kept uniform without constantly making the tappet chamber side negative.

  According to the fifth aspect of the present invention, the lubricating oil can be supplied to the gear positioned above the oil level of the lubricating oil accommodated in the gear case, and the sucked lubricating oil can be effectively used.

Next, embodiments of the invention will be described.
1 is a side sectional view showing an overall configuration of a fuel injection pump according to an embodiment of the present invention, FIG. 2 is a side sectional view of a plunger and a tappet, and FIG. 3 is a block diagram showing a controller of the fuel injection pump. FIG. 4 is a graph showing the relationship between the cam phase angle and the cam speed. In the present invention, the left-right direction in FIG. 1 is the front-rear direction of the fuel injection pump 1, and the up-down direction in FIG.

  As shown in FIGS. 1 and 2, the fuel injection pump 1 is configured by vertically joining a pump housing 2 and a hydraulic head 3. An electronic governor device 4 for electrically controlling the fuel injection amount of the engine is disposed on the front side of the pump housing 2 (left side in FIG. 1), and a gear case 67 is disposed on the rear side of the pump housing 2. Has been.

A plunger barrel 8 is inserted into the hydraulic head 3, and a plunger 7 is slidably mounted in the plunger barrel 8, and the tappet 12 is moved by rotation of the cam 6 formed on the camshaft 5. The plunger 7 is configured to slide up and down.
A fuel pressure chamber 19 for compressing the fuel oil flowing in from the fuel gallery 14 by the plunger 7 is formed in the space inside the plunger barrel 8 above the plunger 7.

  In the pump housing 2, a sliding hole 15 a is formed in the vertical direction above the cam 6 formed on the camshaft 5 and below the plunger barrel 8. The lower portion of the plunger 7, the plunger spring 34, and the upper spring receiver 33 are accommodated, and the space between the tappet 12 and the plunger barrel 8, in other words, the space inside the tappet 12 is configured as a tappet chamber 15. The cam 6 is disposed in a cam chamber 13 formed in the pump housing 2. The cam chamber 13 is an outer space below the tappet 12.

  As shown in FIGS. 1 and 2, the tappet 12 includes a tappet body 35, a tappet pin 37, a tappet roller 11, a lower spring receiver 31, and the like. The tappet main body 35 is configured in a bowl shape with the top open, and a tappet pin 37 is horizontally mounted in the bottom of the tappet main body 35, and the tappet roller 11 is rotatably supported on the tappet pin 37. The tappet roller 11 is disposed so as to contact the outer peripheral surface of the cam 6. However, the tappet 12 may be configured not to include the tappet roller 11 and the tappet pin 37.

A lower spring receiver 31 and a ring 36 are accommodated in the upper portion of the tappet body 35. The lower spring receiver 31 is formed at the center of the disk with a protrusion 31b protruding upward, and the lower end of the plunger 7 is locked to the protrusion 31b. The lower end of the plunger spring 34 is fitted around the protrusion 31 b of the lower spring receiver 31 and inserted from above the tappet body 35. Note that the tappet main body 35 and the lower spring receiver 31 can be configured integrally.
The ring 36 prevents the upper surface of the tappet roller 11 from coming into contact with the lower spring receiver 31 so that the tappet roller 11 rotates smoothly, and lubricating oil is easily discharged from the vent hole 32 described later. It is for doing so. The ring 36 is interposed between the bottom of the tappet main body 35 and the lower spring receiver 31, and forms a space between the tappet roller 11 and the lower spring receiver 31.

  An upper spring receiver 33 is disposed above the tappet 12. The upper spring receiver 33 is formed in a cylindrical shape, and penetrates the hydraulic head 3 at the upper end thereof and is fitted on the lower portion of the plunger barrel 8. A control sleeve 41 is rotatably interposed between the upper spring receiver 33 and the lower portion of the plunger barrel 8.

At the lower end portion of the upper spring receiver 33, an annular step portion having a large diameter on the lower side is formed on the inner peripheral portion, and the upper end portion of the plunger spring 34 is fitted into the step portion. A plunger spring 34 is interposed between the upper spring receiver 33 and the lower spring receiver 31, and the lower spring receiver 31 is urged downward by the urging force of the plunger spring 34. As a result, the plunger 7 and the tappet 12 are moved. It is biased downward.
Thus, when the cam 6 is rotated, the tappet 12 slides up and down in the sliding hole 15a, and at the same time, the plunger 7 moves up and down, and the fuel oil supplied into the upper fuel pressure chamber 19 is pumped. Will be.

Next, the structure of the lower spring receiver 31 of the tappet 12 will be described.
The lower spring receiver 31 is provided with an air vent hole 32 for communicating the tappet chamber 15 and the cam chamber 13 on the inner and outer sides of the tappet 12, that is, the lower spring receiver 31 constituting the tappet 12. 32 is disposed at a position where it is not blocked by the plunger spring 34, the plunger 7, or the like. The vent hole 32 is a hole provided to eliminate the pressure difference between the tappet chamber 15 and the cam chamber 13 and to remove the lubricating oil accumulated in the tappet chamber 15 when the tappet 12 slides up and down. is there.

Next, a configuration for sucking the lubricating oil in the tappet chamber 15 will be described.
A communication hole 51 for communicating the tappet chamber 15 with the outside of the pump housing 2 is formed. In other words, the communication hole 51 is formed from the outside of the pump housing 2 toward the tappet chamber 15. A suction passage 53 is provided at the outer end of the communication hole 51 for connection to the suction side of a vacuum pump 52 serving as a suction means via a joint 56. The vacuum pump 52 is constituted by, for example, a vacuum pump, and power is transmitted from the crankshaft or is driven by an actuator such as a motor provided outside the engine to suck the lubricating oil in the tappet chamber 15. Is.

  In the middle of the suction passage 53, an on-off valve 60 composed of an electromagnetic valve is provided. As shown in FIGS. 1 and 3, the solenoid of the on-off valve 60 is connected to a controller 61 serving as a control means, and the on-off valve 60 is controlled to open and close by the controller 61, and suction is turned on and off by the vacuum pump 52. It is possible to do. The controller 61 is connected with an angle sensor 65 for detecting the phase angle of the camshaft 5 as engine rotation detecting means. The angle sensor 65 also serves as a rotational speed sensor and is disposed on the front side of the camshaft 5. The camshaft 5 is linked to a crankshaft (not shown) via a gear or the like, and the angle sensor 65 can also detect the phase angle of the camshaft 5 at the same time. It can be detected. Thereby, the raising / lowering position of the tappet 12 can be detected. Further, it is possible to calculate the rotation speed and cam speed of the camshaft 5 from the detection value of the angle sensor 65, and thereby it is possible to know the rising speed of the tappet 12. The angle sensor and the rotational speed sensor can be provided separately and connected to the controller 61, respectively.

  When the cam 6 is in the upward stroke, that is, the phase angle of the camshaft 5 in FIG. 4 is between θ0 and θTOP, and the cam speed of the cam 6 is equal to the set value. The camshaft 5 is opened only when it is equal to or higher than the set speed V, and is closed when the phase angle of the camshaft 5 is equal to or lower than other positions and the set speed V. With this configuration, particularly when the cam 6 is in the ascending stroke and the cam speed of the cam 6 is equal to or higher than the set speed V as in the rated operation indicated by the solid line in FIG. Since the amount of lubricating oil discharged from the lubricating oil pump (not shown) to the cam chamber 13 increases and the lubricating oil splashes easily, a large amount of lubricating oil enters the tappet chamber 15. By sucking the lubricating oil with the suction force generated by the vacuum pump 52, the contamination on the plunger 7 (fuel pressure chamber 19) side is reduced. Further, when the cam 6 is in the downward stroke, no lubricating oil is mixed into the fuel pressure chamber 19 side, and the cam speed of the cam 6 is set at the set speed V as in idling shown by a one-dot chain line in FIG. When the pressure is less than the lower limit, the amount of lubricating oil discharged from the lubricating oil pump into the cam chamber 13 is small, and the lubricating oil does not enter the tappet chamber 15 so much. Stop. With this configuration, the amount of lubricating oil supplied to the sliding hole 15a decreases excessively when sucked at all times, preventing excessive suction of the lubricating oil and moderate lubrication to prevent seizure of the plunger 7 and the like. can do.

  The controller 61 may be configured to share the same controller as the controller used to control the electronic governor device 4. With this configuration, it is not necessary to add a new controller, and the cost can be reduced.

  Lubricating oil sucked by the vacuum pump 52 is discharged into the gear case 67 through a return passage 54 connected to the discharge side of the vacuum pump 52. That is, one end of the return passage 54 is connected to the discharge side of the vacuum pump 52, and the other end is connected to a gear case side communication hole 67 a and a joint 57 formed in the upper part of the gear case 67 connected to the outside of the pump housing 2. Connected through. As a result, the lubricating oil discharged through the return passage 54 passes through the gear case side communication hole 67a and is discharged into the gear case 67, and from the gear case 67 into the pump housing 2 or into a crankcase (not shown). It will circulate. Further, the pump housing 2 or the crankcase does not become excessively negative pressure.

  The gear case side communication hole 67 a is provided above a gear 68 disposed in the gear case 67. When a plurality of gears are present, a gear case side communication hole 67a is disposed above the gear 68 positioned at the uppermost position. With this configuration, when the lubricating oil is collected in the gear case 67, it falls onto the gear 68, and the gear train meshing with the gear 68 can be lubricated. Since the gear 68 is located above the oil level in the crankcase filled with the lubricating oil, it is difficult to supply the lubricating oil. Therefore, the gear case side communication hole 67a is provided above the gear 68 to facilitate the supply of lubricating oil to the gear 68.

  As described above, the fuel injection pump 1 has the tappet 12 attached to the lower portion of the plunger 7, the cam 6 is disposed in contact with the lower surface of the tappet 12, and the cam 7 is rotated to rotate the plunger 7. In the fuel injection pump 1 that reciprocates and pressure-feeds fuel oil, a communication hole 51 that communicates the tappet chamber 15 that houses the tappet 12 and the outside of the pump housing 2 in which the tappet chamber 15 is provided is provided. A vacuum pump 52 is connected to the hole 51. By configuring in this way, the vacuum pump 52 sucks out the lubricating oil floating in the tappet chamber 15 and the excess lubricating oil from the lubricating oil that has entered the tappet chamber 15 to forcibly. This makes it possible to prevent the lubricating oil from adhering to the plunger 7 and entering the fuel oil through the gap between the plunger 7 and the plunger barrel 8. As a result, sulfides and the like contained in the exhaust gas can be reduced.

  The fuel injection pump 1 is provided with an opening / closing valve 60 in a suction passage 53 that connects the communication hole 51 and the vacuum pump 52, and the opening / closing valve 60 and the angle sensor 65 are connected to a controller 61. The cam phase is detected, and the on-off valve 60 is controlled to open and close at the set phase. With this configuration, since the suction of the lubricating oil by the vacuum pump 52 can be performed at the set phase, it can be efficiently sucked when a large amount of splashing of the lubricating oil occurs, preventing excessive suction of the lubricating oil. Burn-in can be prevented.

  The on-off valve 60 is controlled to open when the phase is during the upward stroke of the plunger 7 and the cam speed of the cam 6 is equal to or higher than a set speed V. With this configuration, since the suction is performed only when the plunger 7 is raised and the cam speed is equal to or higher than the set speed V, the mixing of the lubricating oil into the fuel pressure chamber 19 can be reduced. By closing the on-off valve 60, it is possible to prevent excessive suction of the lubricating oil and prevent the plunger 7 from being seized. Thereby, the stable operation of the fuel injection pump 1 is possible, and the durability of the fuel injection pump 1 is improved.

  Further, the fuel injection pump 1 has the other end of the return passage 54 connected to the discharge side of the vacuum pump 52 connected to a gear case 67 connected to the pump housing 2. With this configuration, the entire amount of the lubricating oil in the engine housing can be kept constant by returning the sucked lubricating oil to the gear case 67. Further, the internal pressure of the engine housing can be kept uniform without constantly making the tappet chamber 15 side negative.

  The connection position of the other end of the return passage 54 is above the gear 68 accommodated in the gear case 67. With this configuration, the lubricating oil can be supplied to the gear 68 positioned above the oil level of the lubricating oil accommodated in the gear case 67, and the sucked lubricating oil can be effectively used. .

1 is a side sectional view showing an overall configuration of a fuel injection pump according to an embodiment of the present invention. Side surface sectional drawing of a plunger and a tappet. The block diagram which shows the controller of a fuel injection pump. The graph which shows the relationship between a cam phase angle and cam speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection pump 2 Pump housing 6 Cam 7 Plunger 12 Tappet 13 Cam chamber 15 Tappet chamber 31 Lower spring receiver 32 Vent hole 51 Communication hole 52 Vacuum pump

Claims (5)

In a fuel injection pump that attaches a tappet to the lower part of the plunger, arranges the cam so as to contact the lower surface of the tappet, and reciprocates the plunger by rotating the cam to pump fuel oil.
A tap hole that houses the tappet and a communication hole that communicates with the outside of the pump housing in which the tappet chamber is provided, and a suction means is connected to the communication hole;
A fuel injection pump characterized by that. An opening / closing valve is provided in the suction passage connecting the communication hole and the suction means, the opening / closing valve and the engine rotation detection means are connected to the control means, the phase of the cam is detected by the engine rotation detection means, and the set phase is set. Controlled to open and close the on-off valve,
The fuel injection pump according to claim 1. The on-off valve is controlled to open when the phase is during the upward stroke of the plunger and the cam speed of the cam is greater than or equal to a set value.
The fuel injection pump according to claim 2. The other end of the return passage connected to the discharge side of the suction means was connected to a gear case connected to the pump housing.
The fuel injection pump according to claim 1. The connection position of the other end of the return passage was above the gear accommodated in the gear case,
The fuel injection pump according to claim 4.

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