JP2011185111A - Fuel supply pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of a fuel supply pump, which prevents influence of the inclination of a cam shaft 4 on seizure resistance. <P>SOLUTION: An outer peripheral surface 23 of a bearing 22 is formed into an elliptic surface swelling toward an outer peripheral side, then, the bearing 22 can be inclined when the elliptic outer peripheral surface 23 slides relative to a support hole forming surface 24. Thereby, even if a camshaft 5 is inclined, since part, in which the surface pressure is locally high, dose not exists between the camshaft 5 and the bearing 22, the inclination of the camshaft 5 has no influence on the seizure resistance between the camshaft 5 and the bearing 22. As a result, the structure of fuel supply pump preventing an influence of the inclination of the camshaft 5 on seizure resistance can be provided. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a fuel supply pump that supplies fuel to an engine.

  Conventionally, for example, in an accumulator fuel injection device that injects and supplies fuel at a high pressure exceeding 100 MPa, the fuel is increased in pressure by a fuel supply pump 100 as shown in FIG. 5 and supplied to an accumulator.

  The fuel supply pump 100 includes, for example, a plunger 102 that forms a fuel pressurizing chamber 101, a cam 103 that linearly reciprocates the plunger 102, and a cam 103 that is rotated by an engine (not shown). The cam shaft 104 is provided. The fuel supply pump 100 expands or contracts the pressurizing chamber 101 by the reciprocating movement of the plunger 102, thereby sucking fuel into the pressurizing chamber 101 and pressurizing and discharging fuel from the pressurizing chamber 101 (for example, , See Patent Document 1).

  Further, according to the fuel supply pump 100, the cam 103 is integrated with the cam shaft 104 between one axial end and the other end of the cam shaft 104, and the cam shaft 104 is substantially disc-shaped at one axial end. A rotating body 105 is mounted, and driving force is transmitted from the engine via the rotating body 105. The cam shaft 104 is supported at a portion between the one end in the axial direction and the cam 103 by being accommodated in a predetermined support hole 106 via a bearing 107.

  By the way, the rotating body 105 attached to one end of the cam shaft 104 in the axial direction is, for example, a gear, and the engine output is transmitted through a chain wound around the gear. For this reason, a load is always applied to the rotating body 105 in one direction, and the cam shaft 104 tends to incline with respect to the axis of the support hole 106 due to this load. A part where the surface pressure is locally generated is generated between them.

For example, as shown in FIG. 5B, when a load is applied to the rotating body 105 upward in the figure, between the cam shaft 104 and the bearing 107, the upper left part in the figure and the lower right side in the figure. The surface pressure locally increases at the site.
As a result, the seizure resistance between the cam shaft 104 and the bearing 107 is determined according to the tilt of the cam shaft 104, and therefore a structure is desired in which the tilt of the cam shaft 104 does not affect the seizure resistance.

JP 2007-154711 A

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a structure in which the inclination of the cam shaft does not affect the seizure resistance in the fuel supply pump.

[Means of Claim 1]
The fuel supply pump according to claim 1 includes a plunger that forms a fuel pressurizing chamber, a cam that linearly reciprocates the plunger, and a cam shaft that is rotationally driven by the engine and revolves the cam. By enlarging or reducing the pressurizing chamber by the reciprocating motion, the fuel is sucked into the pressurizing chamber and the fuel is pressurized and discharged from the pressurizing chamber.

The cam is integrated with the cam shaft between one end and the other end of the cam shaft in the axial direction. The cam shaft is fitted with a substantially disc-shaped rotating body at one end in the axial direction, and the engine is connected to the cam shaft through the rotating body. A driving force is transmitted from the shaft, and a portion between the one end in the axial direction and the cam is accommodated in a predetermined support hole via a bearing.
The bearing has an inner peripheral surface (hereinafter referred to as a support hole forming surface) that forms a support hole so that its outer peripheral surface bulges in a curved shape on the outer peripheral side and is inclined with respect to the axis of the support hole. )).

Thereby, a bearing can incline because an outer peripheral surface of itself slides with respect to a support hole formation surface. For this reason, even if the camshaft is tilted, there is no local high surface pressure between the camshaft and the bearing, so the camshaft is tilted against seizure between the camshaft and the bearing. Does not affect sex.
As described above, in the fuel supply pump, it is possible to provide a structure in which the inclination of the cam shaft does not affect the seizure resistance.

[Means of claim 2]
According to the fuel supply pump of the second aspect, the support hole forming surface is provided with a groove recessed toward the outer peripheral side substantially parallel to the axial direction, and the outer peripheral surface of the bearing is a ridge that fits into the groove. Are provided substantially parallel to the axial direction, and the bottom of the groove and the top of the ridge extend substantially parallel to the axial direction. The bottom of the groove and the top of the ridge form a gap in the radial direction so that the bearing can be inclined with respect to the axis of the support hole in a state where the ridge is fitted in the groove.
This can prevent the bearing from rotating about its own axis. For this reason, it is possible to prevent the bearing from rotating around the cam shaft in a structure in which the inclination of the cam shaft does not affect the seizure resistance.

[Means of claim 3]
According to the fuel supply pump of the third aspect, the top of the bulge bulges in a curved shape on the outer peripheral side, and slides with respect to the bottom of the groove so that the bearing is inclined with respect to the axis of the support hole. be able to.
This allows the bearing to tilt as the top of the ridge slides against the bottom of the groove.

For this reason, even if the camshaft is tilted, there is no local high surface pressure between the camshaft and the bearing, so the camshaft is tilted against seizure between the camshaft and the bearing. Does not affect sex. Further, by fitting the bulge into the groove, the bearing can be prevented from rotating about its own axis.
As described above, in the fuel supply pump, it is possible to provide a structure in which the inclination of the cam shaft does not affect the seizure resistance, and it is possible to prevent the bearing from rotating around the cam shaft.

1 is an overall configuration diagram of a fuel supply pump (Example 1). FIG. (A) is a perspective view which emphasizes the shape characteristic of a bearing, (b) is explanatory drawing which shows the state in which the cam shaft is not inclined, (c) shows the state in which the cam shaft is inclined. It is explanatory drawing (Example 1). (A) is a perspective view which emphasizes the shape characteristic of a bearing, (b) is explanatory drawing which shows the state which the camshaft is not inclined, (c) is AA sectional drawing of (b). There is (Example 2). (A) is a perspective view which emphasizes the shape characteristic of a bearing, (b) is explanatory drawing which shows the state which a cam shaft is not inclined, (c) is BB sectional drawing of (b). There is (Example 3). (A) is a whole block diagram of a fuel supply pump, (b) is an explanatory view showing a state where a portion having a high surface pressure is locally generated between a camshaft and a bearing (conventional example). .

  The fuel supply pump according to the first embodiment includes a plunger that forms a fuel pressurizing chamber, a cam that linearly reciprocates the plunger, and a cam shaft that is rotationally driven by the engine to revolve the cam. By enlarging or reducing the pressurizing chamber by the movement, the fuel is sucked into the pressurizing chamber and the fuel is pressurized and discharged from the pressurizing chamber.

The cam is integrated with the cam shaft between one end and the other end of the cam shaft in the axial direction. The cam shaft is fitted with a substantially disc-shaped rotating body at one end in the axial direction, and the engine is connected to the cam shaft through the rotating body. A driving force is transmitted from the shaft, and a portion between the one end in the axial direction and the cam is accommodated in a predetermined support hole via a bearing.
The bearing has an inner peripheral surface (hereinafter referred to as a support hole forming surface) that forms a support hole so that its outer peripheral surface bulges in a curved shape on the outer peripheral side and is inclined with respect to the axis of the support hole. )).

  According to the fuel supply pump of the second embodiment, a groove that is recessed toward the outer peripheral side is provided on the support hole forming surface substantially parallel to the axial direction, and a protrusion that fits into the groove is provided on the outer peripheral surface of the bearing. The groove bottom and the ridge top extend substantially parallel to the axial direction. The bottom of the groove and the top of the ridge form a gap in the radial direction so that the bearing can be inclined with respect to the axis of the support hole in a state where the ridge is fitted in the groove.

  According to the fuel supply pump of the third embodiment, the top of the bulge bulges in a curved shape on the outer peripheral side, and the bearing can slide against the bottom of the groove so that the bearing is inclined with respect to the axis of the support hole. it can.

[Configuration of Example 1]
The structure of the fuel supply pump 1 of Example 1 is demonstrated based on drawing.
The fuel supply pump 1 constitutes an accumulator fuel injection device that injects and supplies fuel at a high pressure exceeding 100 MPa, for example, and the fuel whose pressure is increased by the fuel supply pump 1 is sent to a common rail as an accumulator vessel Then, the fuel is distributed and injected from a common rail to a fuel injection valve (not shown) provided for each cylinder of an engine (not shown).

  As shown in FIG. 1, the fuel supply pump 1 includes a plunger 3 that forms a fuel pressurizing chamber 2, a cam 4 that linearly reciprocates the plunger 3, and a cam 4 that is rotated by an engine to revolve the cam 4. A cam shaft 5 is provided, and the pressurizing chamber 2 is expanded or contracted by the reciprocating motion of the plunger 3, thereby sucking fuel into the pressurizing chamber 2 and pressurizing and discharging fuel from the pressurizing chamber 2. .

  In the following description, the axial direction of the cam shaft 5 is referred to as a first axial direction, and the axial direction of the plunger 3 is referred to as a second axial direction. Here, since there are a plurality of plungers 3 at equal angular intervals around the axis of the camshaft 5 for each fuel supply pump 1, the second axial direction is the plunger 3 shown on the upper side of FIG. Define only for.

  The plunger 3 is supported by the cylinder head 7 so as to be slidable in the second axial direction, and forms a pressurizing chamber 2 on one end side in the second axial direction. Further, the plunger 3 has a plunger head 8 to which a driving force is transmitted from the cam 4 at the other end in the second axial direction, and the plunger head 8 is urged to the other side in the second axial direction by a spring 9. It is in sliding contact with a cam ring 10 to be described later.

  Here, low pressure fuel sucked by a feed pump 12 from a fuel tank (not shown) is metered by a suction metering valve 13 and supplied to the pressurizing chamber 2. That is, when the pressurizing chamber 2 is expanded and depressurized by the movement of the plunger 3 to the other side in the second axial direction, the low pressure fuel discharged from the feed pump 12 is opened by opening the check valve 14 on the suction side. Is sucked into the pressurizing chamber 2 through the suction metering valve 13. When the pressurizing chamber 2 is contracted and increased in pressure by the movement of the plunger 3 in the second axial direction, the discharge-side check valve 15 is opened to increase the pressure of the pressurized fuel. 2 is discharged toward the common rail.

  The cam 4 is integrated with the cam shaft 5 so as to be eccentric with respect to the axis of the cam shaft 5 between one end and the other end of the cam shaft 5 in the first axial direction. The cam ring 10 is fitted to the outer periphery of the cam 4 via a bush 17, and the outer peripheral side surface of the cam ring 10 forms a sliding contact surface 18 with which the plunger head 8 is in sliding contact.

  Here, when the camshaft 5 rotates, the cam 4 revolves around the axis of the camshaft 5, so that the sliding contact surface 18 reciprocates in the second axis direction and is perpendicular to the paper surface of FIG. Hereinafter, it is reciprocated in the third direction. As a result, the plunger head 8 reciprocates in the second axis direction and reciprocates relative to the sliding contact surface 18 in the third direction while sliding on the sliding contact surface 18. Reciprocates linearly in the second axis direction.

  The camshaft 5 has a substantially disc-shaped rotating body 19 attached to one end in the first axial direction, and driving force is transmitted from the engine via the rotating body 19 (see FIG. 2). A portion of the cam shaft 5 between the first axial end and the cam 4 is accommodated in a predetermined support hole 21 via a bearing 22. The camshaft 5 is provided with a rotary vane of the feed pump 12 at the other end in the first axial direction. The feed pump 12 is driven by the rotation of the camshaft 5 to suck fuel from the fuel tank and to adjust the suction. Discharge toward the quantity valve 13.

[Features and Effects of Example 1]
According to the fuel supply pump 1 of the first embodiment, as shown in FIG. 2, the bearing 22 has its own outer peripheral surface 23 bulged in an elliptical shape on the outer peripheral side, and is inclined with respect to the axis of the support hole 21. Thus, it can slide with respect to the inner peripheral surface (hereinafter referred to as the support hole forming surface 24) that forms the support hole 21.

  Here, the rotating body 19 attached to one end in the first axial direction of the camshaft 5 is, for example, a gear, and the engine output is transmitted through a chain (not shown) wound around the gear. For this reason, a load is always applied to the rotating body 19 in one direction, and the cam shaft 5 tends to be inclined with respect to the axis of the support hole 21 by this load. For this reason, when the bearing 22 cannot be inclined with respect to the shaft center of the support hole 21, a region where the surface pressure is locally high is generated between the cam shaft 5 and the bearing 22. The seizure resistance between them is determined according to the inclination of the camshaft 5.

On the other hand, by making the outer peripheral surface 23 of the bearing 22 into an elliptical surface that bulges to the outer peripheral side, the bearing 22 is inclined when the elliptical outer peripheral surface 23 slides with respect to the support hole forming surface 24. be able to. For this reason, even if the camshaft 5 is inclined, a portion where the surface pressure is locally high is not generated between the camshaft 5 and the bearing 22. Therefore, the camshaft 5 is inclined with respect to the camshaft 5 and the bearing 22. No effect on seizure resistance.
As described above, in the fuel supply pump 1, it is possible to provide a structure in which the inclination of the cam shaft 5 does not affect the seizure resistance.

[Example 2]
According to the fuel supply pump 1 of the second embodiment, as shown in FIG. 3, two grooves 26 that are recessed toward the outer peripheral side are supported on the support hole forming surface 24 substantially in parallel with the first axial direction. It is provided so as to be line symmetric with respect to the axial center of the hole 21 as a central axis. In addition, on the outer peripheral surface 23 of the bearing 22, ridges 27 that fit into the respective grooves 26 are provided so as to be substantially parallel to the first axial direction and line-symmetric with respect to the axis of the bearing 22 as the central axis.

The bottom 28 of the groove 26 and the top 29 of the ridge 27 extend substantially parallel to the first axial direction, and the bottom 28 of the groove 26 and the top 29 of the ridge 27 are in the state where the ridge 27 is fitted in the groove 26. A gap 30 is formed in the radial direction so that 22 can be inclined with respect to the axis of the support hole 21.
Thereby, since it can prevent that the bearing 22 rotates centering | focusing on its own shaft center, it can prevent that the bearing 22 carries around to the cam shaft 5. FIG. The bearing 22 can be inclined by sliding the outer peripheral surface 23 with respect to the support hole forming surface 24 as in the first embodiment.

Example 3
According to the fuel supply pump 1 of the third embodiment, as shown in FIG. 4, the top 29 of the ridge 27 bulges in an elliptical arc shape on the outer peripheral side, and the bearing 22 is inclined with respect to the axis of the support hole 21. Thus, it can slide against the bottom 28 of the groove 26. Note that portions of the bearing 22 other than the ridges 27 are provided in a cylindrical shape.

Thereby, the bearing 22 can be inclined by the top 29 sliding relative to the bottom 28. For this reason, even if the camshaft 5 is inclined, a portion where the surface pressure is locally high is not generated between the camshaft 5 and the bearing 22. Therefore, the camshaft 5 is inclined with respect to the camshaft 5 and the bearing 22. No effect on seizure resistance. Further, by fitting the ridge 27 into the groove 26, the bearing 22 can be prevented from rotating about its own axis.
As described above, in the fuel supply pump 1, it is possible to provide a structure in which the inclination of the cam shaft 5 does not affect the seizure resistance, and it is possible to prevent the bearing 22 from rotating around the cam shaft 5.

[Modification]
The mode of the fuel supply pump 1 is not limited to the first to third embodiments, and various modifications can be considered. For example, according to the fuel supply pump 1 of the first and second embodiments, the outer peripheral surface 23 of the bearing 22 swells in an elliptical shape, but the shape of the outer peripheral surface 23 of the bearing 22 is not limited to an elliptical shape, Any curved surface shape may be used as long as the shape bulges to the outer peripheral side.

Further, according to the fuel supply pump 1 of the third embodiment, the top 29 of the ridge 27 bulges in an elliptical arc shape, but the shape of the top 29 of the bulge 27 is not limited to an elliptical arc shape, and bulges to the outer peripheral side. Any curved shape may be used as long as it has a shape.
Moreover, in Example 2, 3, although the groove | channel 26 and the protrusion 27 were each provided in two places, you may make it provide the groove | channel 26 and the protrusion 27 only in one place each.

DESCRIPTION OF SYMBOLS 1 Fuel supply pump 2 Pressurization chamber 3 Plunger 4 Cam 5 Cam shaft 19 Rotor 21 Support hole 22 Bearing 23 Outer peripheral surface 24 Support hole formation surface (Inner peripheral surface which forms a support hole)
26 Groove 27 Raised 28 Bottom (groove bottom)
29 Top (the top of the bump)
30 gap

Claims (3)

A plunger that forms a fuel pressurizing chamber; a cam that linearly reciprocates the plunger; and a cam shaft that is rotationally driven by an engine to revolve the cam.
In the fuel supply pump that expands or contracts the pressurizing chamber by reciprocating movement of the plunger, and sucks fuel into the pressurizing chamber and pressurizes and discharges fuel from the pressurizing chamber.
The cam is integrated with the cam shaft between one end and the other end in the axial direction of the cam shaft,
The cam shaft is mounted with a substantially disc-shaped rotating body at one end in the axial direction, a driving force is transmitted from the engine via the rotating body, and a portion between the one end in the axial direction and the cam is predetermined. Are accommodated through bearings in the support holes,
The bearing has its outer peripheral surface bulged in a curved shape on the outer peripheral side, and can slide with respect to the inner peripheral surface forming the support hole so as to be inclined with respect to the axis of the support hole. A fuel supply pump characterized. The fuel supply pump according to claim 1, wherein
On the inner peripheral surface forming the support hole, a groove recessed toward the outer peripheral side is provided substantially parallel to the axial direction, and on the outer peripheral surface of the bearing, a ridge that fits in the groove is substantially parallel to the axial direction. The bottom of the groove and the top of the ridge extend substantially parallel to the axial direction,
The bottom of the groove and the top of the ridge form a gap in the radial direction so that the bearing can be inclined with respect to the axis of the support hole in a state where the ridge is fitted in the groove. A fuel supply pump characterized by that. A plunger that forms a fuel pressurizing chamber; a cam that linearly reciprocates the plunger; and a cam shaft that is rotationally driven by an engine to revolve the cam.
In the fuel supply pump that expands or contracts the pressurizing chamber by reciprocating movement of the plunger, and sucks fuel into the pressurizing chamber and pressurizes and discharges fuel from the pressurizing chamber.
The cam is integrated with the cam shaft between one end and the other end in the axial direction of the cam shaft,
The cam shaft is mounted with a substantially disc-shaped rotating body at one end in the axial direction, a driving force is transmitted from the engine via the rotating body, and a portion between the one end in the axial direction and the cam is predetermined. Are accommodated through bearings in the support holes,
On the inner peripheral surface forming the support hole, a groove recessed toward the outer peripheral side is provided substantially parallel to the axial direction, and on the outer peripheral surface of the bearing, a ridge that fits in the groove is substantially parallel to the axial direction. The bottom of the groove and the top of the ridge extend substantially parallel to the axial direction,
The top of the bulge bulges in a curved shape on the outer peripheral side, and is capable of sliding relative to the bottom of the groove so that the bearing is inclined with respect to the axis of the support hole. pump.

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