JP2012072704A - Pump tappet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump tappet 21 having a structure of a detent pin 24 contributing to reduction in weight of the pump tappet 21.SOLUTION: A detent pin 24 has a hollow structure by bending working of a steel plate, for example, to reduce the weight. The reciprocating movement speed of the pump tappet 21 is thereby increased, and high-pressure fuel is achieved by the increase in fuel compression stroke amount or by the increase in fuel compression frequency. Accordingly, it contributes to improvements in the fuel efficiency of a direct-injection engine.

Description

  The present invention relates to a pump tappet, and more particularly to a pump tappet provided with a roller bearing.

  In an automobile direct injection engine, a high pressure fuel pump is used to inject high pressure fuel into a cylinder. The high-pressure fuel pump is driven by a cam or the like, and a pump tappet is used between the pump plunger and the cam in order to efficiently transmit the rotational force of the cam to the reciprocating motion of the pump plunger (piston).

  A technique related to a high-pressure pump including a tappet for a pump is disclosed in DE 10 2005 047 234 A1 (Patent Document 1). FIG. 19 is a cross-sectional view showing a part of the high-pressure pump of Patent Document 1.

  The high-pressure pump shown in Patent Document 1 is in contact with a camshaft 1 that rotates in the direction of arrow A in FIG. 19, a cam 2 provided on the outer diameter side of the camshaft, and the cam 2. The rotary motion of the camshaft 1 is transmitted as a reciprocating linear motion to a pump plunger 3 (hereinafter simply referred to as “plunger”), and a tappet 4 that performs the reciprocating linear motion, and a rod-shaped that abuts the tappet 4 and performs the reciprocating linear motion. The plunger 3 as a member, a high-pressure chamber (not shown) for sending fuel according to the reciprocating linear motion of the plunger 3 and increasing the pressure, and the tappet 4 are in contact with each other so that the plunger 3 is arranged on the inner side. And a housing 6 that accommodates the tappet 4, the plunger 3, and the spring 5.

  The tappet 4, the plunger 3 and the spring 5 are arranged so as to be accommodated in a guide hole 7 provided in the housing 6. The tappet 4 is guided by the inner diameter surface of the guide hole 7 in the vertical direction in FIG. 17, that is, in the direction of the arrow XVII in FIG.

  As described above, the tappet 4 enters the guide hole 7 and is reciprocated by the cam 2, but the anti-rotation pin 9 a is attached to the outer diameter portion of the tappet 4 so that the tappet 4 does not rotate in the circumferential direction in the guide hole 7. It has been.

  When the tappet 4 is accommodated in the guide hole 7, the non-rotating pin 9 a is accommodated in the concave groove 7 a provided on the inner diameter surface of the guide hole 7, thereby rotating the tappet 4 in the circumferential direction in the guide hole 7. It is preventing.

  For example, the non-rotating pin 9a disclosed in Patent Literature 1 and Patent Literature 2 has a cylindrical shape as shown in FIG. 20, for example, and is press-fitted and fixed in a mounting hole 9 b formed in the peripheral wall of the case 9. Yes.

DE 10 2005 047 234 A1 (Fig. 7) Japanese Patent No. 3823819 (FIGS. 2 and 4)

By the way, in recent years, in order to improve the combustion efficiency (improving fuel efficiency) of a direct injection engine, the fuel has been advanced to a higher pressure (and miniaturized), and in a fuel pump, the amount of fuel compression stroke has increased for higher pressure. (= Cam lift amount increase) and fuel compression frequency increase (= cam lift frequency increase) are required. When the cam lift amount is increased or the number of cam lifts is increased, the pump tappet reciprocates at a higher speed, so that the inertial force acting on the pump tappet is increased, the followability is deteriorated, and problems such as jumping may occur. In order to improve the followability, it is necessary to reduce the weight of the tap tappet and to keep the inertial force small.

  Accordingly, an object of the present invention is to provide a tappet for a pump having a detent pin structure that can contribute to weight reduction of the tappet.

  In order to solve the above-mentioned problems, the present invention is provided with a rotation prevention pin accommodated in a concave groove formed in an inner diameter surface of a guide hole of a housing on the outer surface of a case accommodating a shaft and a roller bearing. In the pump tappet in which the pin mounting hole is provided in the peripheral wall of the case, the rotation prevention pin has a hollow structure to reduce the weight.

  The anti-rotation pin has a hollow structure, for example, by bending a steel plate.

  The non-rotating pin consists of a semi-cylindrical part that is housed in a concave groove formed in the inner diameter surface of the guide hole, and a mounting leg that is press-fitted into the mounting hole of the case. Also good. By providing the burrs, it is possible to more reliably prevent the rotation prevention pins from coming off.

  Furthermore, you may perform a crowning process on the outer peripheral surface of a rotation prevention pin. When the pump tappet is tilted in the guide hole, the locking pin also tilts with respect to the groove in the guide hole. Therefore, the end (corner) of the locking pin comes into contact with the groove in the guide hole and wears the guide hole groove. There are concerns. For this reason, by providing a crowning on the outer peripheral surface of the non-rotating pin, even when the tappet for the pump is tilted, it is possible to prevent the concave groove of the guide hole from contacting the end (corner) of the non-rotating pin. The wear of the hole groove can be prevented.

  The crowning may be provided at the same time as pressing, or may be provided by post-processing such as machining.

  As described above, the present invention reduces the weight by making the non-rotating pin into a hollow structure, so that the reciprocating speed of the pump tappet can be increased, and the fuel high pressure is increased by increasing the amount of fuel compression stroke and increasing the number of times of fuel compression. Can contribute to improving fuel efficiency of direct injection engines (leading to improved fuel efficiency).

It is sectional drawing which shows a part of high-pressure pump containing the tappet which concerns on one Embodiment of this invention. It is a vertical front view of the tappet contained in the high pressure pump shown in FIG. It is a vertical side view of the tappet contained in the high pressure pump shown in FIG. FIG. 4 is a perspective view of the tappet shown in FIGS. 2 and 3. It is the figure which looked at the tappet shown in FIG. 4 from the direction of arrow V in FIG. It is the figure which looked at the tappet shown in FIG. 4 from the direction of arrow VI in FIG. It is the figure which looked at the tappet shown in FIG. 4 from the direction of arrow VII in FIG. It is the cross-sectional view which looked at the tappet shown in FIG. 4 from the direction of arrow VIII in FIG. It is an expanded vertical cross-sectional view which shows an example of a rotation prevention pin. It is an expanded vertical cross-sectional view which shows the other example of a rotation prevention pin. It is a partial vertical side view which shows the relationship with the guide hole of the tappet of this invention. It is a partial vertical side view which shows the relationship between the other example of a non-rotating pin, and the guide groove of a guide hole. It is a partial vertical side view which shows the relationship between the other example of a non-rotating pin, and the guide groove of a guide hole. It is an enlarged view of the part shown by XIV of the tappet shown in FIG. It is the figure which looked at a part of roller bearing contained in the tappet shown in FIG. 2 from the direction of arrow XV in FIG. It is sectional drawing of a part of roller bearing contained in the tappet shown in FIG. 2, and is sectional drawing cut | disconnected by XVI-XVI in FIG. It is a vertical front view which shows other embodiment of the tappet which concerns on this invention. It is a vertical side view which shows other embodiment of the tappet which concerns on this invention. It is sectional drawing which shows a part of high pressure pump containing the conventional tappet. It is an expansion perspective view which shows the relationship between the conventional non-rotating pin and the attachment hole of a tappet.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
A high pressure pump 11 including a tappet according to an embodiment of the present invention has a cam 12a provided on the outer diameter side thereof, a camshaft 12 that rotates in the direction of arrow A in FIG. The tappet 21 that abuts and transmits the rotational motion of the camshaft 12 as a reciprocating linear motion to a pump plunger 13 (hereinafter simply referred to as “plunger”) and performs the reciprocating linear motion, and the reciprocating linear motion abutting the tappet 21. A plunger 13 as a rod-shaped member for performing the above operation, a high-pressure chamber (not shown) for sending fuel in accordance with the reciprocating linear motion of the plunger 13, abutting the tappet 21, and placing the plunger 13 on the inner side A spring 14 provided as described above, and a housing 15 that houses the tappet 21, the plunger 13, and the spring 14. .

  The tappet 21, the plunger 13 and the spring 14 are arranged so as to be accommodated in a guide hole 16 provided in the housing 15. The tappet 21 is guided by the inner diameter surface 16a of the guide hole 16 in the vertical direction in FIG. 1, that is, in the direction of the arrow I in FIG.

  The camshaft 12 and the tappet 21 are arranged so that the outer diameter surface 12b of the cam 12a and the outer diameter surface 32a of the outer ring 32 of the roller bearing 31 included in the tappet 21 abut. One end 13 a of the plunger 13 is disposed so as to abut on an intermediate bottom 23 c provided in a case 23 included in the tappet 21. The spring 14 is arranged so that one end thereof is in contact with a spring seat 17 provided on the lower side of the intermediate bottom 23c.

  The spring 14 has an elastic force in the downward direction, that is, in the direction opposite to the direction indicated by the arrow I in FIG. The tappet 21 is urged upward by the elastic force of the spring 14 through the plunger 13, that is, in the direction indicated by the arrow I in FIG. 1.

  The tappet 21 and the plunger 13 are moved in the vertical direction, that is, in the direction of the arrow I in FIG. 1 or vice versa, by the rotational movement of the camshaft 12, the urging of the spring 14, and the guide of the inner diameter surface 16a of the guide hole 16. Reciprocating linear motion in the direction of. The reciprocating linear motion here is a motion in the direction of arrow I in FIG. 1 or in the opposite direction. When the camshaft 12 rotates at a high speed, the speed of the reciprocating linear motion of the tappet 21 and the plunger 13 also increases.

  The high pressure chamber is disposed on the other end side (not shown) of the plunger 13. The reciprocating linear motion of the plunger 13 can increase the pressure of the fuel supplied to the high pressure chamber.

  Next, the configuration of the tappet 21 according to an embodiment of the present invention will be described. The tappet 21 includes a shaft 22, a roller bearing 31 that is disposed on the outer diameter side of the shaft 22 and is rotatably supported on the shaft 22, and a case 23 that houses the shaft 22 and the roller bearing 31.

  The case 23 includes a cylindrical peripheral wall 23a and an intermediate bottom 23c provided at an intermediate position on the inner diameter surface 23b of the peripheral wall 23a so as to partition the space in the vertical direction. Of the case 23, the intermediate bottom 23 c is in contact with the plunger 13. The peripheral wall 23a and the intermediate bottom 23c have a predetermined thickness.

  As shown in FIG. 3, a pair of support holes 23 d and 23 e that support the shaft 22 are provided on one end side of the peripheral wall 23 a. The shaft 22 is arranged so that the shaft 22 is inserted into the pair of support holes 23d and 23e. A roller bearing 31 is disposed on the outer diameter side of the shaft 22. Thus, the case 23 accommodates the shaft 22 and the roller bearing 31 in the space 23f from the intermediate bottom 23c toward the one end side of the peripheral wall 23a.

  The shaft 22 is formed in a hollow shape, and is fixed to the support holes 23d and 23e by caulking and fixing the outer peripheral edge portion of the end surface of the shaft 22. Reference numeral 22a indicates a caulking portion. By making the shaft 22 hollow, the weight can be reduced as compared with the case of using a solid shaft.

  A part of the plunger 13 is accommodated in the space 23g from the intermediate bottom 23c toward the other end side of the peripheral wall 23a. Specifically, the one end portion 13a of the plunger 13 is disposed so as to contact the central portion in the radial direction of the intermediate bottom 23c, and the one end portion 13a of the plunger 13 is accommodated. Note that one end of the spring 14 is also accommodated in the space 23g.

  The middle bottom 23c is provided with four oil holes 25 penetrating in the thickness direction (see FIG. 7). The four oil holes 25 are provided so as to avoid a contact portion between the one end portion 13a of the plunger 13 and the intermediate bottom 23c. By using this oil hole 25, the lubricating oil supplied to the tappet 21 can be passed between the space 23f and the space 23g.

  As shown in FIG. 2, the case 23 is provided with a mounting hole 23i as a recess penetrating from the outer diameter surface 23h to the inner diameter surface 23b of the peripheral wall 23a. A locking pin 24 is fitted into the mounting hole 23i so that a part thereof protrudes from the outer diameter surface 23h. The locking pin 24 positions the tappet 21 disposed in the guide hole 16. That is, the tappet 21 includes a rotation prevention pin 24 that positions the case 23.

  The anti-rotation pin 24 has a hollow structure, and includes a semi-cylindrical portion 24b accommodated in a concave groove 16b formed in the inner diameter surface of the guide hole 16, and an attachment leg portion 24a press-fitted into the attachment hole 23i of the case 23. It is formed by bending a steel plate.

  The base portion of the semi-cylindrical portion 24 b is formed in a bowl shape wider than the width between the opposing mounting leg portions 24 a so that the rotation prevention pin 24 does not fall into the mounting hole 23 i of the case 23.

  Further, although the mounting leg 24a of the locking pin 24 is press-fitted into the mounting hole 23i, as shown in FIG. 10 at the tip of the mounting leg 24a in order to prevent the locking pin 24 from falling off more securely. It is preferable to provide the burrs 24c.

  A concave groove 16b extending in the direction of arrow I in FIG. 1 is provided on the inner diameter surface 16a of the guide hole 16 of the housing 15 so as to be recessed from the inner diameter surface 16a. When the tappet 21 is accommodated in the guide hole 16, the semi-cylindrical portion 24b from which the rotation prevention pin 24 protrudes is fitted into the concave groove 16b. As a result, the case 23 in the guide hole 16 and the tappet 21 are positioned in the circumferential direction. Thereby, the rotation of the tappet 21 in the circumferential direction in the guide hole 16 is prevented.

  The tappet 21 moves up and down with the locking pin 24 housed in the concave groove 16b of the guide hole 16, but when the tappet 21 moves up and down, the tappet 21 may be tilted in the guide hole 16 as shown in FIG. is there.

Then, since the rotation prevention pin 24 is also inclined with respect to the concave groove 16b of the guide hole 16,
There is a concern that the end portion (corner portion) of the rotation prevention pin 24 comes into contact with the concave groove 16 of the guide hole 16 and wears the concave groove 16b of the guide hole 16.

  For this reason, as shown in FIGS. 12 and 13, by providing a crowning on the outer peripheral surface of the detent pin 24, even when the tappet 21 is inclined, the groove 16b of the guide hole 16 and the end of the detent ( It is possible to suppress the contact of the corners) and to prevent the groove 16b of the guide hole 16 from being worn.

  FIG. 12 is an example in which only the both ends are crowned while leaving a straight portion at the center of the outer peripheral surface of the rotation prevention pin 24, and FIG. 13 is an example in which the entire outer peripheral surface is crowned.

  The crowning process may be provided at the same time as the pressing process, or may be provided by post-processing such as machining.

  Next, the configuration of the roller bearing 31 included in the tappet 21 will be described. FIG. 14 is an enlarged view of the portion indicated by XIV of the two-dot chain line in FIG. A roller pitch circle 31a is shown by a one-dot chain line in FIG. FIG. 15 is a view of a part of the roller bearing 31 seen from the direction of the arrow XV shown in FIG. FIG. 16 is a cross-sectional view showing a part of the roller bearing 31, and is a cross-section XVI-XVI in FIG. The roller bearing 31 includes an outer ring 32, a plurality of rollers 33 disposed between the outer ring 32 and the shaft 22, and a cage 34 that holds the plurality of rollers 33.

  The retainer 34 includes a pair of annular portions 34 a and 34 b and a plurality of column portions 34 d that connect the pair of annular portions 34 a and 34 b so as to form a pocket 34 c that accommodates the rollers 33. The column portion 34d has a shape extending straight in the axial direction, that is, in the cross section shown in FIG.

  Similar to the rollers 33, the retainer 34 is disposed between the outer ring 32 and the shaft 22. The plurality of rollers 33 are accommodated and held in the respective pockets 34 c provided in the cage 34. The retainer 34 is configured such that the outer diameter guide, that is, the inner diameter surface 32 b of the outer ring 32 disposed on the outer diameter side of the retainer 34 and the outer diameter surface 34 e of the retainer 34 are in radial contact. Further, the retainer 34 is provided with an oil groove 34f so as to be recessed inward from the outer diameter surface 34e. The oil groove 34f is provided at the center of the column portion 34d and has a shape extending in the circumferential direction.

  Due to the rotational movement of the camshaft 12, the outer ring 32 and the rollers 33, which are constituent members of the roller bearing 31, are also rotated. When the camshaft 12 rotates at a high speed, the rotation of the rollers 33 also increases. Here, in the roller bearing 31 which is a constituent member of the tappet 21, the position of the roller 33 in the roller bearing 31 at the time of high speed rotation can be stabilized by the cage 34. Then, the skew of the roller 33 can be suppressed and the lateral running of the roller bearing 31 can be prevented. Accordingly, it is possible to reduce the risk of poor lubrication of the roller bearing 31 and wear of the roller bearing 31 during high-speed rotation. That is, such a pump tappet can be manufactured at a low cost and can have a long life.

  Moreover, since such a high-pressure pump 11 includes the tappet 21 that can reduce the risk of poor lubrication of the roller bearing 31 and wear of the roller bearing 31 during high-speed rotation, it can be manufactured at low cost. The fuel pressure can be increased more stably in a short time.

  Here, the retainer 34 is an outer diameter guide, and the retainer 34 and the outer ring 32 are provided on the outer diameter surface 34e of the retainer 34 because an oil groove 34f that is recessed inward from the surface is provided. And the radial position of the cage 34 can be stabilized. Further, the oil permeability of the inner diameter surface 34g of the cage 34 and the outer diameter surface 22a of the shaft 22 is improved, and the lubricity between the outer diameter surface 34e of the cage 34 and the inner diameter surface 32b of the outer ring 32 is improved and retained. Wear of the vessel 34 and the outer ring 32 can be suppressed. Therefore, the life of the cage 34, the rollers 33, the outer ring 32, and the shaft 22 can be extended. The oil groove may be provided so as to extend with an inclination in the axial direction, or may be provided so as to extend in a curved manner. A plurality of oil grooves may be provided.

  The cage 34 is an inner diameter guide, and an oil groove may be provided on the inner diameter surface 34 g of the cage 34. By carrying out like this, the holder | retainer 34 and the shaft 22 can be made to contact and the radial position of the holder | retainer 34 can be stabilized. Further, the oil permeability of the outer diameter surface 34e of the cage 34 and the inner diameter surface 32b of the outer ring 32 is improved, and the lubricity between the inner diameter surface 34g of the cage 34 and the outer diameter surface 22a of the shaft 22 is improved and retained. Wear of the vessel 34 and the shaft 22 can be suppressed. Therefore, the life of the cage 34, the rollers 33, the outer ring 32, and the shaft 22 can be extended.

  The cage 34 provided in the roller bearing 31 may be made of resin. By carrying out like this, the holder | retainer 34 itself can be made lightweight and the weight of the tappet 21 can be lightened generally. Therefore, the force required for the reciprocating linear motion, here, the force required for the vertical movement of the tappet 21 can be reduced. Further, when the cage 34 is made of resin, it can be manufactured by injection molding or the like, so that mass production is facilitated and it can be manufactured at low cost. Examples of the material of the cage 34 include nylon 66, nylon 46, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), and the like. If necessary, the resin may be filled with carbon fiber, glass fiber, carbon black, or the like.

  In FIG. 15, the dimension of the clearance between the rolling surface 33a of the roller 33 accommodated in the pocket 34c and the side wall surface 34h of the column portion 34d is exaggerated and greatly illustrated from the viewpoint of facilitating understanding. Yes.

  In addition, the roller and shaft which comprise the above-mentioned tappet are manufactured by forging, cutting, etc. of steel members, for example, SUJ2 and SCM420 (all are JIS standards).

  Here, in the above-described embodiment, the mounting hole 23i for fitting the rotation-preventing pin is a mounting hole penetrating from the inner diameter surface of the case 23 to the outer diameter surface. The hole 23 i may not penetrate from the inner diameter surface of the case 23 to the outer diameter surface.

  In the above-described embodiment, the cage includes a pair of annular portions and a plurality of pillar portions, but is not limited thereto, and is divided into a plurality of members instead of an integrated type, A spacer-type cage disposed between the rollers may be used.

  Moreover, in the said embodiment, although the pillar part was made into the shape extended straightly to an axial direction, it is not restricted to this, For example, the pillar part may be bent by radial direction, for example, a V-type holder, It may be shaped like an M-type cage. Furthermore, it is good also as providing the roller stop part which prevents the fall-off | omission of the roller of the radial direction on the side wall surface of a pillar part.

  In the above-described embodiment, the roller bearing is configured to include a cage that holds a plurality of rollers. However, the configuration is not limited thereto, that is, a configuration in which the roller bearing does not include a cage, that is, a full-roller type. The same applies to roller bearings.

  The above embodiment is the tappet 21 in which the roller bearing 31 is provided on the outer diameter side of the shaft 22, but the embodiment shown in FIGS. 17 and 18 omits the rolling elements and the outer ring on the outer diameter side of the shaft 22. It is an example of the tappet 21 directly provided 32a so that rotation is possible, the part which is common in the said embodiment attaches the same code | symbol, and abbreviate | omits description.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The tappet according to the present invention is included in a high-pressure pump that supplies fuel to an engine such as an automobile, and is effectively used as a part for an automobile.

11 High Pressure Pump 12 Cam Shaft 12a Cam 13 Plunger 13a One End 15 Housing 16 Guide Hole 16a Inner Diameter 16b Groove 21 Tappet 22 Shaft 23 Case 23a Peripheral Wall 23c Intermediate Bottom 23i Mounting Hole 24 Detent Pin 24a Mounting Leg 24b Half Cylindrical portion 24c Burr 31 Roller bearing 32 Outer ring 33 Roller

Claims (7)

A tappet for a pump that transmits a rotary motion of a camshaft provided with a cam to a pump plunger as a reciprocating linear motion, and performs a reciprocating linear motion in a guide hole of a housing together with the pump plunger,
A shaft, a roller bearing disposed on the outer diameter side of the shaft, and rotatably supported on the shaft; and a case that accommodates the shaft and the roller bearing; and an inner diameter of a guide hole of the housing on the outer surface of the case A pump tappet characterized by comprising a detent pin housed in a concave groove formed on the surface, a mounting hole for the detent pin being provided in the peripheral wall of the case, and the detent pin having a hollow structure.   The pump tappet according to claim 1, wherein the hollow structure rotation prevention pin is formed by bending a steel plate.   3. The anti-rotation pin according to claim 1 or 2, comprising a semi-cylindrical portion 2 having a hollow structure and accommodated in a concave groove formed in an inner diameter surface of the guide hole, and an attachment leg portion press-fitted into an attachment hole of the case. The pump tappet as described.   The tappet for a pump according to claim 3, wherein a drop for preventing dropping is provided at a tip of the mounting leg portion.   The tappet for a pump according to any one of claims 1 to 4, wherein a crowning is provided on an outer peripheral surface of the rotation prevention pin.   A high pressure fuel pump using the pump tappet according to any one of claims 1 to 5. An automobile or a motorcycle using the high-pressure fuel pump according to claim 6.

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