JP5040856B2 - Lubricating oil supply device for fuel pump - Google Patents

Description

  The present invention relates to a lubricating oil supply device that supplies lubricating oil to a fuel pump.

  2. Description of the Related Art Conventionally, fuel pumps that pressurize fuel by reciprocating a plunger by a pump cam formed on a cam shaft are widely known. A timing chain is wound around the camshaft sprocket so that the driving force from the crankshaft is transmitted. Lubricating oil is supplied to the portion where the sprocket and the timing chain come into contact.

Patent Document 1 discloses a lubrication device in which an oil groove is formed on an end surface of a sprocket around which a timing chain is wound, and lubrication between the sprocket and the timing chain is ensured by lubricating oil supplied from the oil groove. .
JP 9-209731 A

  However, when the oil groove is formed in the rotating sprocket as in the lubricating device described in Patent Document 1, a plurality of oil grooves are provided to sufficiently supply the lubricating oil to a portion where the sprocket and the timing chain are in contact with each other. Has to be formed on the sprocket, resulting in an increase in the amount of lubricating oil supplied.

  Therefore, the present invention has been made paying attention to such problems, and an object thereof is to provide a lubricating oil supply device for a fuel pump that can suppress an increase in the supply amount of the lubricating oil.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  In the lubricating oil supply device of the fuel pump (30) that pressurizes and supplies fuel by reciprocating the plunger (31), the present invention provides a pump cam (23A) for reciprocating the plunger (31) and a pump cam (23A). A cam unit (23) having a sprocket (23B) formed coaxially therewith, and a power transmission member (7A) wound around the sprocket (23B) and transmitting the rotation of the crankshaft (2) of the engine (100) And a shaft (21C) that rotatably supports the cam unit (23), a sliding contact portion (21B) that is formed at an end portion of the shaft (21C) and that is in sliding contact with the end surface of the sprocket (23B), and a shaft (21C). ) And an oil passage (50) formed in the shaft (21C) so as to supply lubricating oil between the outer peripheral surface of the cam unit (23) and the sprocket. 23B) and the power transmission member (7A) in the vicinity of the contact position of the sliding contact portion (21B) so that the lubricating oil guided between the shaft (21C) and the cam unit (23) flows out to the outside. And an outflow oil groove (54A) formed on the sliding end surface.

  According to the present invention, since the sprocket and the timing chain are lubricated by the lubricating oil from the outflow oil groove formed in the sliding contact portion of the shaft portion, compared with the conventional method of forming a plurality of oil grooves in the rotating sprocket. Thus, it is possible to suppress an increase in the supply amount of the lubricating oil.

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

  FIG. 1 is a front view of a vehicle engine equipped with a fuel pump.

  As shown in FIG. 1, the engine 100 is a V-type engine and includes a crankshaft 2 that protrudes outward from the cylinder block 1.

  A crank sprocket 3 is provided at the protruding end of the crankshaft 2. The crank sprocket 3 is formed with a large-diameter sprocket 3A and a small-diameter sprocket having a smaller diameter than the large-diameter sprocket 3A arranged side by side on the same axis.

  Cylinder heads 4 </ b> A and 4 </ b> B are fixed to the upper end of the cylinder block 1. From the cylinder heads 4A and 4B, an intake camshaft 5 for opening and closing the intake valve and an exhaust camshaft 6 for opening and closing the exhaust valve respectively protrude outward. An intake sprocket 5 </ b> A is fixed to the protruding end of the intake camshaft 5. An exhaust sprocket 6 </ b> A is fixed to the protruding end of the exhaust camshaft 6.

  A timing chain 7A is wound around the large-diameter sprocket 3A, the intake sprocket 5A on the cylinder head 4A side, and the exhaust sprocket 6A. A timing chain 7B is wound around the large-diameter sprocket 3A and the intake sprocket 5A and the exhaust sprocket 6A on the cylinder head 4B side. As indicated by the arrows in FIG. 1, these timing chains 7A and 7B each circulate clockwise when the engine 100 is viewed from the front.

  Guide rails 8A are provided on the cylinder block 1 facing the tension-side timing chains 7A and 7B to which the crank sprocket 3 transmits driving force. Further, movable tension rails 8B are provided on the cylinder block 1 so as to face the timing chains 7A and 7B on the return side. The tension rail 8B is urged by the chain tensioner 9, and adjusts the tension of the timing chains 7A and 7B by applying pressure to the timing chains 7A and 7B from the side.

  An oil pan 11 is provided at the lower end of the cylinder block 1. From the oil pan 11, an oil pump drive shaft 13 projects outward. An oil pump sprocket 14 is fixed to the protruding end of the oil pump drive shaft 13.

  A timing chain 7 </ b> C is wound around the oil pump sprocket 14 and the small-diameter sprocket 3 </ b> B of the crankshaft 2. The tension of the timing chain 7 </ b> C is adjusted by the tension rail 12 installed on the outer peripheral surface of the oil pan 11. The oil pump drive shaft 13 is rotated by the driving force from the crankshaft 2 transmitted through the small-diameter sprocket 3B, the oil pump sprocket 14 and the timing chain 7C, and drives the oil pump housed in the oil pan 11. To do.

  The engine 100 described above includes a fuel pump 30 that pressurizes and supplies fuel. The fuel pump 30 is driven by a pump drive mechanism 20 provided in the cylinder head 4A. The pump drive mechanism 20 is disposed inside the two cylinder heads 4A and 4B and downstream of the intake sprocket 5A in the circumferential direction of the timing chain 7A.

  FIG. 2 is a schematic configuration diagram of the fuel pump 30.

  As shown in FIG. 2, the fuel pump 30 driven by the pump drive mechanism 20 is a so-called plunger pump, and includes a plunger 31 that reciprocates in a housing 32.

  The plunger 31 is slidably received in a cylinder 32 </ b> A formed in the housing 32. The pump cam 23A of the pump drive mechanism 20 is in sliding contact with the lower end surface of the plunger 31 from below. A fuel chamber 33 is formed in the upper part of the cylinder 32A, and the fuel chamber 33 expands and contracts as the plunger 31 reciprocates in the cylinder 32A. Note that the plunger 31 is urged in a direction of expanding the fuel chamber 33 by an urging member (not shown).

  A fuel suction passage 34 and a fuel discharge passage 35 are formed in the housing 32 so as to face the fuel chamber 33. The fuel suction passage 34 opens at a position communicating with the fuel chamber 33 only when the fuel chamber 33 is enlarged. The fuel discharge passage 35 is opened at a position where it always communicates with the fuel chamber 33. A check valve 36 is provided in the fuel discharge passage 35. The check valve 36 is a valve that allows fuel to be discharged from the fuel chamber 33 while preventing reverse flow of fuel.

  In the fuel pump 30 configured as described above, when the plunger 31 is lowered and the fuel chamber 33 is expanded, the check valve 36 prevents the fuel discharge passage 35 from flowing backward, so that the pressure in the fuel chamber 33 is negative. . As a result, fuel is sucked into the fuel chamber 33 from the fuel suction passage 34 when the sliding plunger 31 opens the fuel suction passage 34.

  Thereafter, when the plunger 31 is raised and the fuel chamber 33 is contracted, the fuel suction passage 34 is closed, and then the fuel pressure in the fuel chamber 33 is increased according to the volume reduction of the fuel chamber 33. The fuel in the fuel chamber 33 whose pressure has increased pushes the check valve 36 open, flows out into the fuel discharge passage 35, and is supplied to a fuel injection valve (not shown).

  Next, the pump drive mechanism 20 that drives the fuel pump 30 will be described with reference to FIG.

  As shown in FIG. 3, the pump drive mechanism 20 includes a shaft portion 21, a bearing 22, a cam unit 23, a spacer 24, and a bracket 25.

  The shaft portion 21 includes a flange 21A that is fixed to the outer peripheral surface of the cylinder head 4A, a sliding contact portion 21B that is provided on the flange 21A and that is in sliding contact with the end surface of the cam unit, and a cylindrical shaft 21C that protrudes from the sliding contact portion 21B. Have A cam unit 23 is inserted into the shaft 21C through a bearing 22 so as to be rotatable.

  The bearing 22 is a needle bearing and includes a cylindrical cage 22A and a plurality of rollers 22B held by the cage 22A. A plurality of through holes extending in the axial direction are formed in the side surface of the cage 22A in the circumferential direction, and the roller 22B is rotatably held in these through holes.

  The cam unit 23 is a cylindrical member through which the bearing 22 is inserted, and integrally forms a pump cam 23A and a cam sprocket 23B for driving the pump cam coaxially. The pump cam 23 </ b> A is in sliding contact with the lower end surface of the plunger 31 of the fuel pump 30. The stroke distance of the reciprocating motion of the plunger 31 depends on the cam profile of the pump cam 23A. In this embodiment, the cam profile is set to be elliptical so that the plunger 31 reciprocates twice while the pump cam 23A rotates once. The timing chain 7A is wound around the cam sprocket 23B.

  The spacer 24 is fixed to the tip surface of the shaft 21C by a bolt 26. The spacer 24 forms a disk portion 24A and a spacer shaft 24B protruding from the disk portion 24A. The cam unit 23 is held at a predetermined axial position on the shaft 21C by the disk portion 24A of the spacer 24 and the sliding contact portion 21B of the shaft portion 21. The spacer shaft 24 </ b> B of the spacer 24 is inserted through the hole 25 </ b> A of the bracket 25. The bracket 25 regulates the displacement of the shaft 21 </ b> C in the transverse direction via the spacer 24.

  FIG. 4 is a view showing the pump drive mechanism 20 assembled to the cylinder head 4A.

  As shown in FIG. 4, the shaft 21C of the shaft portion 21 is fixed to the cylinder head 4A via a flange 21A. The tip of the shaft 21 </ b> C is supported by the chain case 40 via the spacer 24 and the bracket 25. By supporting both ends of the shaft 21C in this way, the shaft 21C can stably support the radial load applied to the pump cam 23A and the cam sprocket 23B of the cam unit 23.

  The spacer shaft 24 </ b> B of the spacer 24 is inserted through the hole 25 </ b> A of the bracket 25. The spacer shaft 24B is supported so as to be slidable in the axial direction with respect to the bracket 25. Even if an error occurs in these dimensions due to thermal expansion of the chain case 40 and the pump drive mechanism 20, the error is absorbed by the relative displacement of the spacer 24 and the bracket 25 in the axial direction.

  The timing chain 7A is wound around the cam sprocket 23B of the cam unit 23 disposed on the shaft 21C via a bearing. The driving force of the crankshaft 2 is transmitted to the cam sprocket 23B via the timing chain 7A. Thus, when the cam sprocket 23B rotates, the pump cam 23A also rotates according to the rotation of the cam sprocket 23B. As the pump cam 23A rotates, the plunger 31 of the fuel pump 30 reciprocates in the cylinder 32A.

  In the pump drive mechanism 20, since the cam sprocket 23B of the cam unit 23 is engaged with the timing chain 7A at a position away from the intake cam shaft 5 and the exhaust cam shaft 6, the pump cam 23A interferes with the intake sprocket 5A and the exhaust sprocket 6A. There is nothing. Therefore, the pump drive mechanism 20 has a high degree of freedom in layout, and the degree of freedom in terms of the dimensions of the cam sprocket 23B.

  The pump drive mechanism 20 is disposed downstream of the intake sprocket 5A with respect to the circulation direction of the timing chain 7A. The slack of the timing chain 7A increases from the downstream to the upstream with respect to the crankshaft 2 in the circulation direction. In other words, the slack of the chain is larger at the position facing the tension rail 8B than at the position facing the guide rail 8A. When the slack of the timing chain 7A is large, a timing phase shift between the crankshaft 2 and the fuel pump 30 occurs. It is preferable to dispose the pump drive mechanism 20 downstream of the intake sprocket 5A in order to reduce the phase shift.

  In the pump drive mechanism 20 described above, lubricating oil is supplied to the bearing 22 and the contact portion between the cam sprocket 23B and the timing chain 7A.

  FIG. 5A is a diagram illustrating the supply of lubricating oil in the fuel pump. FIG. 5B is a diagram illustrating a BB cross section in FIG.

  As shown in FIG. 5A, an oil passage 50 and an oil groove 54 are formed in the shaft portion 21 of the pump drive mechanism 20.

  The oil passage 50 includes a first oil passage 51 and a second oil passage 52.

  The first oil passage 51 is formed in the axial center of the shaft 21 </ b> C of the shaft portion 21 as a through hole extending in the axial direction. The opening on the front end side of the first oil passage 51 is closed by the bolt 26. Lubricating oil from an oil pump is supplied to the base end side of the first oil passage 51.

  The second oil passage 52 is formed by being refracted in the radial direction from the first oil passage 51 as shown in FIG. The second oil passage 52 opens on the circumferential side surface of the shaft 21C. At the opening of the second oil passage 52, a notch 53 is formed by notching a part of the circumferential side surface of the shaft 21C.

  Further, as shown in FIG. 5A, an upper oil groove 54A and a lower oil groove 54B are formed as oil grooves 54 on the end surface of the sliding contact portion 21B of the shaft portion 21. The upper oil groove 54A and the lower oil groove 54B will be described with reference to FIG.

  FIG. 6 is a front view of the shaft portion 21 of the pump drive mechanism 20 as viewed from the VI direction of FIG. FIG. 6 shows a state where only the bearing 22 is arranged on the shaft 21 </ b> C of the shaft portion 21, and a circle C drawn by a broken line in FIG. 6 shows an inner circumferential circle of the cam unit 23.

  As shown in FIG. 6, the upper oil groove 54A is formed to be recessed in the upper end surface of the sliding contact portion 21B and extend in the radial direction. The upper oil groove 54A is provided in the vicinity of a position where the cam sprocket 23B of the cam unit 23 and the timing chain 7A are in contact with each other. The upper oil groove 54A opens in the circumferential side surface of the sliding contact portion 21B in a state where the bearing 22 and the cam unit 23 are arranged on the shaft 21C of the shaft portion 21, and the inner circumferential circle C of the cam unit 23 and the bearing 22 It opens between the outer circumference of the cage 22A.

  The lower oil groove 54B is formed to be recessed in the lower end surface of the sliding contact portion 21B and extend in the radial direction. The lower oil groove 54B is provided on the opposite side of the upper oil groove 54A. The lower oil groove 54B opens in the circumferential side surface of the sliding contact portion 21B in a state where the bearing 22 and the cam unit 23 are disposed on the shaft 21C of the shaft portion 21, and the inner circumferential circle C of the cam unit 23 and the bearing. It opens between the outer circumference circles of 22 cages 22A.

  The lubricating oil in the pump drive mechanism 20 is supplied to the bearing 22 and the contact portion between the cam sprocket 23B and the timing chain 7A via the oil passage 50 and the oil groove 54.

  The lubricating oil pumped from the oil pump flows into the base end side of the first oil passage 51, flows through the first oil passage 51, and is guided from the second oil passage 52 to the notch 53. Lubricating oil guided to the notch 53 is stored in the notch 53 and supplied to a gap between the outer peripheral side of the shaft 21 </ b> C and the inner peripheral side of the cam unit 23 to lubricate the bearing 22.

  The lubricating oil that flows between the shaft 21C and the cam unit 23 flows to the base end side of the shaft 21C and lubricates the sliding contact portion 21B and the sliding contact end surface of the cam unit 23. A part of the lubricating oil flows out from the upper oil groove 54A and the lower oil groove 54B. Lubricating oil from the upper oil groove 54A flows toward the cam sprocket 23B of the cam unit 23 and lubricates the contact portion between the cam sprocket 23B and the timing chain 7A. Further, the lubricating oil from the lower oil groove 54B flows down as it is and returns to the oil pan.

  As described above, the following effects can be obtained in the lubricating oil supply device of the fuel pump in the present embodiment.

  In the pump drive mechanism 20, since the first oil passage 51 and the second oil passage 52 are formed inside the shaft 21C of the shaft portion 21, lubricating oil can be supplied between the shaft 21C and the cam unit 23, and the bearing 22 Can be lubricated. Further, since the bearing 22 is cooled by the lubricating oil, seizure of the bearing 22 is suppressed.

  In the pump drive mechanism 20, the cam sprocket 23B and the timing chain 7A are lubricated by the lubricating oil from the upper oil groove 54A formed in the sliding contact portion 21B of the shaft portion 21 fixed to the cylinder head 4A. An increase in the supply amount of lubricating oil can be suppressed as compared with the conventional method of forming a plurality of oil grooves.

  In the lubricating oil that flows between the shaft 21C and the cam unit 23, foreign matter or the like in the lubricating oil tends to accumulate on the lower side, but the lower oil groove 54B is formed on the lower side of the sliding contact portion 21B. Lubricating oil can escape to the outside. Therefore, lubricating oil containing foreign matter is not supplied to the cam sprocket 23B and the timing chain 7A.

  If there is lubricating oil between the shaft 21C and the cam unit 23 when the engine is started, the lubricating oil itself becomes friction depending on the viscosity of the lubricating oil, and the rotation of the cam unit 23 is inhibited. In the pump drive mechanism 20, since the lubricating oil between the shaft 21C and the cam unit 23 is discharged from the lower oil groove 54B when the engine is stopped, the rotation of the cam unit 23 is not hindered. Even if the amount of lubricating oil is small when the engine is started, the cam unit 23 rotates smoothly by the action of the bearing 22.

  Since the upper oil groove 54A and the lower oil groove 54B open between the inner periphery of the cam unit 23 and the outer periphery of the retainer 22A of the bearing 22, the end of the retainer 22A is connected to the upper oil groove 54A and the lower oil groove 54A. There is no overlap with the groove 54B. Therefore, the end of the cage 22A and the upper oil groove 54A and the lower oil groove 54B are not in contact with each other, and the pressure at the contact position does not become excessive, so that seizure of the cage 22A is suppressed.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

It is a front view of the engine for vehicles provided with the fuel pump. It is a schematic block diagram of a plunger type fuel pump. It is a schematic block diagram of the pump drive mechanism which drives a fuel pump. It is a figure which shows the pump drive mechanism assembled | attached to the cylinder head. It is a figure explaining supply of lubricating oil in a fuel pump. It is a front view of the axial part of a pump drive mechanism.

Explanation of symbols

100 Engine 20 Pump drive mechanism 30 Fuel pump 1 Cylinder block 2 Crankshaft 3 Crank sprocket 4A Cylinder head 5A Intake sprocket 6A Exhaust sprocket 7A Timing chain (power transmission member)
21 Shaft portion 21A Flange 21B Sliding contact portion 21C Shaft 22 Bearing 22A Cage 22B Roller 23 Cam unit 23A Pump cam 23B Cam sprocket 24 Spacer 25 Bracket 31 Plunger 33 Fuel chamber 50 Oil passage 51 First oil passage 52 Second oil passage 53 Notch 54A Upper oil groove (outflow oil groove)
54B Lower oil groove (flowing oil groove)

Claims (6)

In a lubricating oil supply device of a fuel pump that pressurizes and supplies fuel by reciprocating a plunger,
A cam unit having a pump cam for reciprocating the plunger, and a sprocket formed coaxially with the pump cam;
A power transmission member wound around the sprocket and transmitting the rotation of the crankshaft of the engine;
A shaft that rotatably supports the cam unit;
A sliding contact portion formed at an end portion of the shaft and in contact with the end surface of the sprocket;
An oil passage formed in the shaft so as to supply lubricating oil between an outer peripheral surface of the shaft and an inner peripheral surface of the cam unit;
In the vicinity of the contact position between the sprocket and the power transmission member, it is formed on the sliding contact end surface of the sliding contact portion so that the lubricating oil guided between the shaft and the cam unit flows out to the outside. An oil spill groove,
A lubricating oil supply device for a fuel pump, comprising: The sliding contact part further forms a falling oil groove on the lower sliding contact end surface for flowing the lubricating oil guided between the shaft and the cam unit to the outside.
The lubricating oil supply device for a fuel pump according to claim 1. The cam unit is rotatably disposed on the shaft via a bearing.
The lubricating oil supply device for a fuel pump according to claim 2. The bearing is a needle bearing composed of a cylindrical cage and a roller held by the cage.
The lubricating oil supply device for a fuel pump according to claim 3. The outflow oil groove and the downflow oil groove are formed to open between the inner peripheral surface of the cam unit and the outer peripheral surface of the cage, as well as opening on a side surface of the sliding contact portion.
The lubricating oil supply device for a fuel pump according to claim 4. The oil passage is a first oil passage formed inside the shaft and at the shaft center of the shaft, and a second oil formed so as to open from the first oil passage to the outer peripheral surface of the shaft. A passage and
6. The lubricating oil supply device for a fuel pump according to claim 1, wherein the lubricating oil supply device is a fuel pump.

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