JP4569563B2 - Cam mechanism mounted device - Google Patents

Description

  The present invention relates to a cam mechanism mounting device including a roller and a tappet between a cam crest and a plunger, and particularly relates to a technique in which a roller and a tappet slide directly.

Conventionally, a high-pressure fuel pump (supply pump) is known as an example of a cam mechanism mounting device including a roller and a tappet between a cam crest and a plunger.
A high-pressure fuel pump for a vehicle includes a camshaft driven by an engine and a plunger driven by a height displacement of a cam crest as the camshaft rotates, and the plunger is driven by the camshaft to reciprocate. Then, the volume of the pressurizing chamber at the end of the plunger fluctuates to suck and pump fuel.

As shown in FIGS. 12 and 13, between the cam crest J1 and the plunger J2, a roller J3 that contacts the cam crest J1 and a tappet J4 that rotatably supports the roller J3 are disposed.
As a support structure of the roller J3 by the tappet J4, (i) a pin type (not shown) in which a pin is used for the rotation shaft of the roller J3 and the tappet J4 supports this pin, and (ii) the outer peripheral surface of the roller J3 is the tappet J4. There is known a direct sliding type (see Patent Documents 1 and 2) that slides directly.
The pin type has a large physique, a large number of parts, and a large number of assembly steps. Therefore, there is an increasing demand for using a direct sliding type.

However, the direct sliding type has the following problems.
(1) When the fuel is pressurized by the lift of the plunger J2, the fuel pressure load of the plunger J2 is transmitted to the tappet J4. For this reason, the upper portion of the tappet J4 receives a large concentrated load F at a contact portion with the plunger J2 (hereinafter referred to as a plunger contact portion). As a result, the portion directly below the plunger contact portion is distorted toward the roller J3, and the contact surface pressure between the roller J3 and the tappet J4 immediately below the plunger contact portion is locally high as shown by the solid line X in FIG. Become. For this reason, the seizure of the sliding surface between the roller J3 and the tappet J4 is likely to occur starting from directly below the plunger contact portion.

(2) On the other hand, the concentrated load F received from the plunger contact portion acts to expand the roller sliding diameter (inner diameter of the roller holding hole J5) with respect to the tappet J4, as shown in FIG. . When the roller sliding diameter is increased, the contact area between the roller J3 and the tappet J4 is reduced, and the contact surface pressure between the roller J3 and the tappet J4 is increased. For this reason, seizure is likely to occur on the sliding surfaces of the roller J3 and the tappet J4.

There is known a technique for solving the problems (1) and (2) described above by employing a means for increasing the strength of the tappet J4 by increasing the size of the tappet J4, such as increasing the thickness of the center portion of the tappet J4. However, since the physique and weight of the tappet J4 become large, the physique of the high-pressure fuel pump becomes large, and there arises a problem that it becomes an obstacle to speeding up the pump rotation.
In the above description, the problem of the prior art has been described by taking the high-pressure fuel pump as an example. However, the type in which the roller J3 and the tappet J4 slide directly causes the same problem as described above.
Japanese Patent Application Laid-Open No. 2004-218459 JP 2004-324535 A

  The present invention has been made in view of the above-described problems, and its object is to reduce the local concentration of the contact surface pressure between the roller and the tappet without increasing the size of the tappet, and to slide the roller and the tappet. It is in providing the cam mechanism mounting apparatus which can prevent the burning in.

[Means of claim 1]
The cam mechanism mounting device employing the means of claim 1 is such that the outer peripheral surface of the roller slides directly with the tappet, and the tappet is provided with a gap (gap) on an extension of the center line of the plunger.
The concentrated load applied to the plunger abutting portion is dispersed in the tappet by the gap, and the contact surface pressure between the roller and the tappet is locally increased. Thereby, the seizure on the sliding surface of the roller and the tappet can be prevented without increasing the size of the tappet.
Specifically, (a) by dispersing the concentrated load applied to the plunger contact portion to both sides of the roller in the rotation axis direction, the problem of locally increasing the contact surface pressure between the roller and the tappet can be avoided. .
Further, (b) the concentrated load applied to the plunger abutting portion is distributed to the both sides in the vertical direction of the rotating shaft of the roller so that the roller sliding diameter can be prevented from being increased. The problem that the contact surface pressure between the roller and the tappet is locally increased can be avoided.

In addition, the tappet is provided by combining a tappet body that slides directly on the roller and a tappet attachment that abuts on the plunger, and the gap is formed between the tappet body and the tappet attachment.
Thereby, formation of a space part becomes easy.

Further, the tappet attachment is fitted into the recess of the tappet body, and the portion of the contact portion between the tappet body and the tappet attachment that is pressurized by the cam crest lift is in the axial direction of the plunger. It is an inclined surface which inclines and the inclination direction narrows toward the insertion direction of a tappet attachment .
Thereby, the load received by the tappet attachment can be converted into an oblique direction by the inclined surface, and the transmission direction of the load transmitted to the tappet body can be controlled. That is, it is possible to further disperse the load transmitted to the tappet body by the inclined surface.

[Means of claim 2 ]
The cam mechanism mounting device adopting the means of claim 2 is a high-pressure fuel pump that pressurizes and discharges fuel by the height displacement of the cam crest, and the plunger performs suction and pressurization of the fuel by reciprocal displacement. is there.
In combination with the means of claim 1 , the tappet can be miniaturized and the seizure prevention performance in the vicinity of the roller during the pump operation can be improved.

The cam mechanism mounting device is disposed between a cam crest whose height is displaced by rotation and a plunger that is reciprocally driven by the height displacement of the cam crest, a roller that contacts the cam crest, and the roller and the plunger. And a tappet arranged between the two.
In the best mode, the tappet is provided with a combination of a tappet body that slides directly on the roller and a tappet attachment that comes into contact with the plunger and fits into the recess of the tappet body, and extends the center line of the plunger. A space is formed between the tappet body and the tappet attachment on the line.
In addition, the contact portion between the tappet body and the tappet attachment and the portion that receives the pressure applied by the lift of the cam crest is inclined with respect to the plunger axial direction, and the inclination direction is narrowed toward the insertion direction of the tappet attachment. It has a surface.
In the following, specific embodiments will be described using the figures as much as possible with respect to the eleventh example. Examples 1 to 6 and Example 11 are reference examples showing examples to which the present invention is not applied, and Examples 7 to 10 show examples to which the present invention is applied.

As a reference example of the present invention, the first embodiment of the high pressure fuel pump (supply pump), will be described with reference to FIGS. In the first embodiment, the schematic configuration of the high-pressure fuel pump will be described first with reference to FIGS. 2 and 3, and then the main part will be described with reference to FIG.
The high pressure fuel pump is applied to, for example, a common rail type fuel injection device of a diesel engine (hereinafter referred to as an engine), and pressurizes fuel supplied from a fuel tank via a low pressure pump (feed pump) to a high pressure. This is a fuel pump that supplies pressure to the tank.
In the first embodiment, the camshaft side (lower side in FIG. 2) of the high-pressure fuel pump is described as lower and the solenoid valve side (upper side in FIG. 2) is upper for the sake of explanation. However, this embodiment is limited to the actual mounting direction. It is not something.

The high-pressure fuel pump includes a pump housing 1 that is fixed to an engine or the like, and a cylinder body 2 that is coupled to the pump housing 1 while being inserted into the pump housing 1.
A cam chamber 3 is formed on the lower side of the pump housing 1. The cam chamber 3 accommodates a cam shaft 4 driven by an engine. A cam crest 5 is formed on the camshaft 4 integrally with the camshaft 4. A plurality of cam ridges 5 are formed in the circumferential direction (three in this embodiment) in order to reciprocate a plunger 7 to be described later a plurality of times (three in this embodiment) when the camshaft 4 makes one rotation. Yes.

  The cylinder body 2 is formed with a cylindrical cylinder hole 6 extending in the vertical direction. A plunger 7 having a cylindrical bar shape is supported inside the cylinder hole 6 so as to be reciprocally slidable in the vertical direction through a minute clearance. A pressurizing chamber (fuel compression chamber) 8 for performing pressure is formed. The upper end of the cylinder hole 6 communicates with the fuel supply side (low pressure side) via the electromagnetic valve 9, and the pressurizing chamber 8 and the fuel supply side are opened and closed by the electromagnetic valve 9.

  A fuel supply pipe 11 that receives low-pressure fuel from the outside (feed pump) is connected to the side surface of the pump housing 1, and the low-pressure fuel supplied to the fuel supply pipe 11 is between the pump housing 1 and the cylinder body 2. It is supplied to an annular fuel reservoir 12 formed therebetween. On the other hand, the solenoid valve 9 is fixed to the top of the cylinder body 2, and an annular low pressure chamber 13 is formed between the solenoid valve 9 and the cylinder body 2. The cylinder body 2 is formed with a low-pressure fuel passage 14 that communicates the fuel reservoir 12 and the low-pressure chamber 13. As a result, the low pressure fuel supplied to the fuel supply pipe 11 is guided to the low pressure chamber 13 around the electromagnetic valve 9.

  A fuel discharge pipe 15 that discharges high-pressure fuel pressurized in the pressurizing chamber 8 to the outside (common rail) is connected to the side surface of the pump housing 1. The cylinder body 2 is formed with a high-pressure fuel passage 16 that connects the pressurizing chamber 8 and the fuel discharge pipe 15, and the fuel pressurized in the pressurizing chamber 8 passes through the high-pressure fuel passage 16 to the fuel discharge pipe. 15 is discharged. A discharge valve 17 that opens at a predetermined pressure or higher and discharges a fuel pressure higher than a predetermined pressure to the outside is provided inside the fuel discharge pipe 15.

The electromagnetic valve 9 is a combination of a low pressure chamber 13 around the electromagnetic valve 9, a valve 21 that communicates and shuts off the pressurizing chamber 8 at the upper end of the plunger 7, and an electromagnetic actuator 22 that drives the valve 21 to open and close. Is.
The valve 21 includes a valve body 23 and a valve body 24. When the valve body 24 is driven upward, the communication between the low pressure chamber 13 and the pressurizing chamber 8 is interrupted, and when the valve body 24 is driven downward. The low pressure chamber 13 and the pressurizing chamber 8 are communicated.

  The electromagnetic actuator 22 includes a solenoid (electromagnet) 25, an armature 26, a return spring 27, and the like. When the solenoid 25 is energized through a connector 28 provided on the upper portion, the armature 26 coupled to the valve body 24 is As a result of magnetic attraction upward, the communication between the low pressure chamber 13 and the pressurizing chamber 8 is blocked. Further, when energization is stopped, the valve body 24 is driven downward by the action of the return spring 27, and the low pressure chamber 13 and the pressurizing chamber 8 communicate with each other.

  The solenoid valve 9 (solenoid 25 of the solenoid actuator 22) is energized and controlled by an ECU (abbreviation of engine control unit: controller: not shown), and the ECU controls the energization timing of the solenoid valve 9. Thus, the amount of pressurized fuel in the pressurizing chamber 8 is controlled, and the flow rate of fuel discharged from the fuel discharge pipe 15 to the common rail is adjusted.

  The lower end of the plunger 7 is coupled to the lower sheet 32 by a plunger head 31 having an enlarged diameter. The upper surface of the lower seat 32 is in contact with the lower end of the coil spring 33 in the axial direction in the pump housing 1, and the lower end surface of the plunger 7 is pressed against the upper surface of a tappet 36 described later by the urging force of the coil spring 33. It touches. The upper end of the coil spring 33 is in contact with the upper seat 34, and the upper seat 34 is restricted from moving upward by the cylinder body 2.

  In the pump housing 1, a tappet cylinder 35 is formed above the cam chamber 3. Inside the tappet cylinder 35, a tappet 36 is supported so as to be slidable back and forth in the vertical direction. The side surfaces of the tappet cylinder 35 and the tappet 36 are provided with parallel surfaces extending along the axial direction (vertical direction), and the tappet 36 is not rotatable about the axial direction (see FIG. 3). . 3 is a guide having a role of a spring guide for preventing the radial displacement of the coil spring 33 and a role of a sliding guide between the tappet 36 and the tappet cylinder 35.

Between the tappet 36 and the cam mountain 5, a roller 37 that is rotatable along the cam mountain 5 is disposed. The roller 37 has a cylindrical shape and is rotatably supported by the tappet 36, and the roller 37 is in contact with the cam crest 5 by the urging force of the coil spring 33.
Specifically, as shown in FIG. 3, a roller holding hole 38 that supports the roller 37 so as to be rotatable and slidable is formed below the tappet 36. The roller holding hole 38 is a circular hole that holds the roller 37 through a sliding clearance, and allows the roller 37 to slide freely with the lower part of the outer peripheral surface of the roller 37 exposed below the lower surface of the tappet 36. Hold.
The penetrating shaft of the roller holding hole 38 (the rotating shaft of the roller 37) is formed in parallel with the rotating shaft of the camshaft 4 so that the straight portion of the cam crest 5 and the straight portion of the roller 37 coincide with each other. Yes.

  2, the drive shaft core of the plunger 7, the drive shaft core of the tappet 36, the rotation shaft core of the roller 37, and the rotation shaft core of the camshaft 4 are provided so as to be aligned on the vertical axis. . As a result, the height displacement of the cam crest 5 accompanying the rotation of the camshaft 4 is transmitted to the plunger 7 via the roller 37 and the tappet 36 on the extension line of the central axis of the plunger 7.

[Features of Example 1]
The high-pressure fuel pump is an example of a cam mechanism mounting device. As shown in the above configuration, the tappet 36 and the roller 37 are arranged between the cam peak 5 and the plunger 7, and the height displacement of the cam peak 5 is changed. Is transmitted to the plunger 7 via the roller 37 and the tappet 36.
Further, as described above, the roller 37 is rotatably supported by the roller holding hole 38 formed in the tappet 36, and the outer peripheral surface of the roller 37 slides directly on the upper curved surface of the roller holding hole 38. is there.

Here, the tappet 36 includes a gap α on an extension line of the central axis of the plunger 7.
As shown in FIG. 1A, the gap portion α of the first embodiment is provided by a through hole 41 that is formed to penetrate from one side surface of the tappet 36 to the other side surface.
Specifically, the through-hole 41 crosses the extension line of the central axis of the plunger 7 just below the contact center of the plunger 7 and the tappet 36, and is orthogonal to the extension line of the central axis of the plunger 7 (the tappet 36 Parallel to the upper surface).

Further, as shown in FIG. 1A, the through hole 41 is formed in a direction perpendicular to the rotation axis of the roller 37 when viewed from above (the drive shaft direction of the plunger 7). As a result, when viewed from the direction perpendicular to the rotation axis of the roller 37, the gap portion α is formed at the center of the left and right of the tappet 36 (center of the roller sliding surface in the axial direction).
In FIG. 1A, as an example of the through-hole 41, a flat hole that is wide in the horizontal direction (wide in parallel with the upper surface of the tappet 36) is shown. However, other hole shapes such as a perfect circle may be used. . Further, the lateral width of the through hole 41 is “a little smaller diameter (for example, contact diameter × 1/2) to slightly larger diameter (for example, contact diameter × 3/2)” than the contact diameter of the plunger 7 and the tappet 36. A range is provided.

(Operation of Example 1)
When the camshaft 4 is rotated by the operation of the engine and the high-pressure fuel pump is operated, the height of the cam crest 5 is displaced vertically on the extension line of the central axis of the plunger 7 as the camshaft 4 rotates.
In the process of increasing the height of the cam peak 5, the height displacement of the cam peak 5 is transmitted to the plunger 7 via the roller 37 and the tappet 36, and the plunger 7 moves up and the fuel supplied to the pressurizing chamber 8 is removed. Pressurize.
On the contrary, in the process in which the height of the cam crest 5 is reduced, the plunger 7, the tappet 36, and the roller 37 are lowered by the urging force of the coil spring 33, and the fuel is sucked into the pressurizing chamber 8.

Here, when the fuel is pressurized during the lift of the plunger 7, a concentrated load (a pressurized load of fuel) is applied from the plunger 7 to the plunger contact portion in the tappet 36. The concentrated load (see arrow F1 in FIG. 1) received at the plunger abutting portion is distributed to both sides of the tappet 36 in the axial direction of the roller 37 by the gap portion α formed in the tappet 36 (see arrow F2 in FIG. 1). )
Thereby, as shown by the solid line A in FIG. 1B, the contact surface pressure between the roller 37 and the tappet 36 is distributed to both sides of the roller 37 in the axial direction. A broken line X in FIG. 1B indicates a distribution state of the contact surface pressure between the roller 37 and the tappet 36 when the gap portion α is not formed in the tappet 36.

(Effect of Example 1)
As described above, the high-pressure fuel pump according to the first embodiment can disperse the concentrated load received at the plunger contact portion on both sides of the roller 37 in the rotational axis direction by providing the gap portion α in the tappet 36. it can. As a result, as shown by a solid line A in FIG. 1B, the contact surface pressure between the roller 37 and the tappet 36 is distributed to both sides in the axial direction of the roller 37, and the contact surface pressure between the roller 37 and the tappet 36 is in contact with the plunger. It is possible to avoid the problem of being locally high immediately below the part.
For this reason, the seizure on the sliding surface of the roller 37 and the tappet 36 can be prevented without increasing the size of the tappet 36.
Further, since the gap portion α is provided in the tappet 36 by forming the through hole 41 in the tappet 36, the number of parts of the tappet 36 is not increased.

A second embodiment will be described with reference to FIG. In the following embodiments, the same reference numerals as those in the first embodiment denote the same functional objects.
In the first embodiment, the through-hole 41 is formed in the direction perpendicular to the rotation axis of the roller 37 as viewed from above, and the concentrated load applied to the plunger contact portion is distributed to both sides of the roller 37 in the rotation axis direction. An example is shown.

On the other hand, in the second embodiment, the through hole 41 is formed in parallel with the rotation axis of the roller 37, and the concentrated load received at the plunger contact portion is distributed to both sides orthogonal to the axial direction by the gap portion α. It is.
In this way, the concentrated load received by the plunger abutting portion is distributed to both sides orthogonal to the axial direction by the gap α, so that the roller sliding diameter (the circular curved surface on the upper side of the roller holding hole 38) is expanded by the concentrated load. The diameter can be prevented, and a problem that the contact surface pressure between the roller 37 and the tappet 36 is locally increased as the diameter is increased can be avoided.

As a result, it is possible to avoid the problem that the contact surface pressure between the roller 37 and the tappet 36 increases due to the increase in the roller sliding diameter, and the contact surface pressure between the roller 37 and the tappet 36 increases. Burn-in on the moving surface can be prevented.
That is, it is possible to avoid the problem that the contact surface pressure between the roller 37 and the tappet 36 is locally increased due to the diameter expansion without increasing the size of the tappet 36 in order to prevent the roller sliding diameter from expanding.

In the third embodiment, both the through hole 41 of the first embodiment (perpendicular to the roller rotation axis) and the through hole 41 of the second embodiment (parallel to the roller rotation axis) are formed in the tappet 36. The hole 41 intersects with a cross just under the plunger contact portion.
As described above, by providing the two through holes 41 so as to cross each other, the effects of both the first embodiment and the second embodiment can be obtained.

A fourth embodiment will be described with reference to FIG.
As shown in FIG. 5A, the tappet 36 according to the fourth embodiment is obtained by joining a tappet body 42 that slides directly on the roller 37 and a tappet attachment 43 that abuts against the plunger 7. It is formed between the tappet body 42 and the tappet attachment 43.

  Specifically, a recess 44 into which the tappet attachment 43 is fitted is formed on the upper surface of the tappet body 42. The tappet attachment 43 of the fourth embodiment has a short columnar shape in the axial direction, and the recess 44 is provided in a cylindrical hole shape. The side surface shape of the tappet attachment 43 and the shape of the concave portion 44 shown in the fourth embodiment are examples for explaining the embodiment, and other shapes are possible as long as the tappet attachment 43 can be joined to the tappet body 42. Also good.

As shown in FIG. 5B, an arcuate groove 45 is formed on the lower surface of the tappet attachment 43, and the arcuate groove 45 is assembled by assembling the tappet attachment 43 to the tappet body 42 by press fitting or the like. And a gap portion α is formed between the upper surface of the recess 44.
Then, as shown in FIG. 5A, the tappet body 42 and the tappet attachment 43 are joined with the direction of the arc-shaped groove 45 (the heel direction) oriented in the direction perpendicular to the rotation axis of the roller 37, Similar to the first embodiment, the concentrated load received by the plunger contact portion can be distributed to both sides of the roller 37 in the rotation axis direction, and the same effect as the first embodiment can be obtained.

  Although not shown, the tappet body 42 and the tappet attachment 43 are joined at the plunger abutting portion in the same manner as in the second embodiment by connecting the tappet body 42 and the tappet attachment 43 so that the direction of the arc-shaped groove 45 is parallel to the rotation axis of the roller 37. The concentrated load can be distributed to both sides orthogonal to the rotation axis direction of the roller 37, and the same effect as in the second embodiment can be obtained.

  Further, an arc-shaped groove 45 is provided on the lower surface of the tappet attachment 43 so as to intersect the cross, the direction of one arc-shaped groove 45 is parallel to the rotation axis of the roller 37, and the direction of the other arc-shaped groove 45 is By joining the tappet body 42 and the tappet attachment 43 so as to face the rotation axis of the roller 37 in the vertical direction, the same effect as in the third embodiment can be obtained.

A fifth embodiment will be described with reference to FIG.
In the fifth embodiment, as shown in FIG. 6A, when the load applied to the plunger contact portion is small, the gap portion α is formed by the arc-shaped groove 45, and as shown in FIG. When the load applied to the contact portion increases, the center of the arcuate groove 45 comes into contact with the bottom surface of the recess 44 in the tappet body 42 due to the deformation of the tappet attachment 43 due to the load, and the gap portion α disappears.
Specifically, the depth of the arc-shaped groove 45 is such that when the load applied to the plunger contact portion reaches, for example, 3/4 to 5/6 of the maximum load, the central portion of the arc-shaped groove 45 is the recess 44. It is provided in contact with the bottom surface. The depth of the arc-shaped groove 45 varies depending on the material and thickness of the tappet attachment 43, the maximum load received from the plunger 7, etc., but is set to about 0.1 μm to several μm, for example.

  By being provided in this way, the load applied to the plunger contact portion is increased, and the central load of the arcuate groove 45 comes into contact with the bottom surface of the recess 44 in the tappet body 42, thereby reducing the concentrated load on both sides of the groove 45. Then, as shown by a solid line B in FIG. 6C, the maximum contact surface pressure between the roller 37 and the tappet 36 can be lowered.

A sixth embodiment will be described with reference to FIG.
In the fourth and fifth embodiments, an example in which the gap α is formed between the tappet body 42 and the tappet attachment 43 by forming the arc-shaped groove 45 on the bottom surface of the tappet attachment 43 has been described.
On the other hand, in the sixth embodiment, a spherical recess 46 is formed on the bottom surface of the tappet attachment 43, thereby forming a gap α between the tappet body 42 and the tappet attachment 43.
Thereby, the same effect as Example 3 can be acquired. Further, since the assembling direction of the tappet attachment 43 is lost, the tappet 36 can be easily manufactured.
The spherical recess 46 may be provided on the tappet body 42 side.

Next, Embodiments 7 to 10 to which the present invention is applied will be sequentially described. First, Embodiment 7 will be described with reference to FIG.
In the above Examples 4 to 6, the vertical contact surface of the tappet body 42 and the tappet attachment 43 (the portion that receives the pressure applied by the lift of the cam crest 5 at the contact portion between the tappet body 42 and the tappet attachment 43), The example provided in a horizontal plane (plane perpendicular | vertical with respect to the extension line of the centerline of the plunger 7) was shown.
On the other hand, in the seventh embodiment, as shown in FIG. 8A, the vertical contact surfaces of the tappet body 42 and the tappet attachment 43 are provided on the inclined surface 47, and the tappet attachment 43 receives from the plunger 7. The load is distributed and transmitted to the outside of the tappet body 42.

Specifically, the tappet attachment 43 of the seventh embodiment has a columnar shape that is short in the axial direction as in the fourth embodiment, and the concave portion 44 is provided in a cylindrical hole shape.
As shown in FIG. 8B, a conical first tapered surface 47 a having a smaller diameter toward the lower side is formed on the outer peripheral edge of the lower surface of the tappet attachment 43.
On the other hand, a second tapered surface 47b having an inclination angle coincident with the first tapered surface 47a is also formed on the outer peripheral edge of the bottom surface of the recess 44.
Then, when the tappet attachment 43 is fitted to the tappet body 42, as shown in FIG. 8A, the first taper surface 47a and the second taper surface 47b coincide with each other, the lower surface (plane) of the tappet attachment 43, and the concave portion A gap portion α is formed between the bottom surface (plane) of 44.

  Thus, by providing the inclined surface 47 with the vertical contact surfaces of the tappet body 42 and the tappet attachment 43, the load applied to the tappet body 42 from the tappet attachment 43 is distributed over a wide range around the tappet body 42. Is transmitted. Thereby, the contact surface pressure of the roller 37 and the tappet 36 is further averaged, and the maximum contact surface pressure can be lowered.

Example 8 will be described with reference to FIG.
The eighth embodiment is a modification of the seventh embodiment, in which the contact surface in the vertical direction between the tappet body 42 and the tappet attachment 43 is an inclined surface 47 formed by a curved surface. A curved taper 48 having a small diameter downward is formed on the periphery.

A ninth embodiment will be described with reference to FIG.
The ninth embodiment is also a modification of the seventh embodiment, in which a chamfered portion 49 is provided at a position facing the lower portion of the tappet attachment 43.
In addition, by assembling the two chamfered portions 49 so as to be aligned in the rotation axis direction of the roller 37, the same effect as in the first embodiment can be obtained.
Further, by assembling the two chamfered portions 49 so as to be aligned in the direction perpendicular to the rotation axis of the roller 37, the same effect as in the second embodiment can be obtained.
Further, the chamfered portions 49 are provided on the lower four surfaces of the tappet attachment 43, and the chamfered portions 49 are assembled with the chamfered portions 49 facing both the rotation axis direction of the roller 37 and the direction perpendicular to the rotation axis of the roller 37. The same effect as in Example 3 can be obtained.

A tenth embodiment will be described with reference to FIG.
The tenth embodiment is a modification of the ninth embodiment, in which the tappet attachment 43 is provided in a prismatic shape. In addition, although not shown in figure, the hole shape of the recessed part 44 of the tappet body 42 is also provided in a square hole shape.

In the first to tenth embodiments, an example in which the gap α is formed inside the tappet 36 has been described.
On the other hand, in the eleventh embodiment, the contact portion between the tappet 36 and the plunger 7 is provided with a recess (not shown), and this recess forms a gap portion α in the contact portion between the tappet 36 and the plunger 7. It is.
The recess is formed on at least one of the upper surface of the tappet 36 or the lower surface of the plunger 7.
Further, the recess may be provided in a groove shape, or may be provided in a hole shape recessed in the axial direction.

[Modification]
In the above embodiment, the type in which the communication between the pressurizing chamber 8 and the low pressure chamber 13 is cut off when the solenoid valve 9 is energized is shown as an example. It may be a high-pressure fuel pump.
In the above embodiment, the pressurization chamber 8 and the low pressure chamber 13 are opened and closed by the electromagnetic valve 9. However, the pressurization chamber 8 and the low pressure chamber are formed by other electric actuator valves such as a piezo valve using a piezo actuator. 13 may be opened and closed.
Further, the present invention may be applied to a high-pressure fuel pump (for example, a row type pump) that varies the fuel discharge pressure by a mechanical configuration (rack & pinion or the like) without using an electric actuator.

  In the above embodiment, an example in which the present invention is applied to a high-pressure fuel pump has been shown. However, the plunger 7 is not limited to the one that pressurizes the fuel, but is a general term for the shaft member that is reciprocally driven. You may apply this invention to the cam mechanism mounting apparatus (for example, industrial robot etc.) which drives drives other than fuel by the reciprocating drive of the plunger 7. FIG.

FIG. 5 is an assembly perspective view of a tappet and a roller showing a part where a through hole is formed, and a distribution diagram of contact surface pressure between the roller and the tappet along the rotation axis direction of the roller (Example 1). (Example 1) which is sectional drawing of a high pressure fuel pump. (Example 1) which is an assembly perspective view of a tappet and a roller. (Example 2) which is the assembly | attachment perspective view of the tappet and roller which shows the formation site | part of a through-hole. (Example 4) which is the assembly figure of a tappet body and a tappet attachment, and a perspective view of a tappet attachment. (Example 5) which is a perspective view which shows the shape change of the circular-arc-shaped groove | channel of a tappet attachment, and the distribution map of the contact surface pressure of the roller and tappet along the rotating shaft direction of a roller. (Example 6) which is a perspective view of a tappet attachment. (Example 7) which is the assembly drawing of a tappet body and a tappet attachment, and a perspective view of a tappet attachment. (Example 8) which is a perspective view of a tappet attachment. (Example 9) which is a perspective view of a tappet attachment. (Example 10) which is a perspective view of a tappet attachment. It is the schematic which looked at the principal part of the high-pressure fuel pump from the rotating shaft direction of a roller, and explanatory drawing of diameter expansion of a roller sliding diameter (conventional example). FIG. 5 is a schematic view of the main part of the high-pressure fuel pump viewed from the direction perpendicular to the roller rotation axis, and a distribution diagram of contact surface pressure between the roller and the tappet along the roller rotation axis direction (conventional example).

Explanation of symbols

5 Cam pile 7 Plunger 36 Tappet 37 Roller 41 Through hole 42 Tappet body 43 Tappet attachment 44 Recess 47 of tappet body Inclined surface α Clearance

Claims (2)

It is arranged between a cam crest whose height is displaced by rotation and a plunger that is driven to reciprocate by the height displacement of this cam crest ,
A roller abutting on the cam crest, and a tappet disposed between the roller and the plunger ,
In the cam mechanism mounting device in which the outer peripheral surface of the roller slides directly with the tappet ,
The tappet is provided in combination with a tappet body that slides directly on the roller, and a tappet attachment that abuts the plunger and fits into a recess of the tappet body, and on an extension of the center line of the plunger. A gap is formed between the tappet body and the tappet attachment,
The contact portion between the tappet body and the tappet attachment and the portion that receives pressure applied by the lift of the cam crest is inclined with respect to the axial direction of the plunger, and the inclined direction faces the insertion direction of the tappet attachment. Cam mechanism mounting device characterized by a sloping surface that narrows . In the cam mechanism mounting device according to claim 1,
This cam mechanism mounting device is a high-pressure device that pressurizes and discharges fuel by the height displacement of the cam crest.
A fuel pump,
The cam mechanism mounting device , wherein the plunger performs suction and pressurization of fuel by reciprocal displacement .

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