JP2007085290A - Plunger driving structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plunger driving structure having balancers of such a shape that does not interrupt the supply of a lubricant to a bearing supporting an eccentric part. <P>SOLUTION: An oil pump 11 comprises a rotating shaft 12 having the eccentric part 12a, the needle roller bearing 13 supporting the eccentric part 12a of the rotating shaft 12, tappets 14 radially disposed in contact with the outer ring of the needle roller bearing 13, plungers 15 disposed on the tappets 14 and reciprocating by the rotation of the rotating shaft 12, and the balancers 16 disposed at both ends of the eccentric part 12a. The surface roughness of the end faces of the outer ring 13b facing the balancers 36 is Rz ≤0.8. Also, the surface roughness of the wall surfaces of the balancers 36 facing the outer ring 13b is Rz ≤3.2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plunger drive structure used for a fuel pump of a diesel engine, an oil pump of a brake device, or the like.

  2. Description of the Related Art Conventionally, an oil pump used for an automobile brake device or the like is described in Japanese Utility Model Laid-Open No. 5-83372 (Patent Document 1). As shown in FIG. 8, an oil pump 1 described in the publication includes a rotating shaft 2 having an eccentric portion 2 a, a ball bearing 3 that supports the eccentric portion 2 a of the rotating shaft 2, and a radial shape on the ball bearing 3. And a plunger 5 which is arranged on the tappet 4 and reciprocates by the rotation of the rotary shaft 2.

  9, the ball bearing 3 includes an inner ring 3a, an outer ring 3b, a plurality of balls 3c disposed between the inner ring 3a and the outer ring 3b, a cage 3d that holds the balls 3, and a bearing. And seal seals 3e for sealing the bearing internal space.

  The oil pump 1 having the above-described configuration performs the suction and pressure feeding of oil by moving the plunger 6 up and down by the rotation of the rotating shaft 2.

  In the publication, the eccentric portion 2a of the rotary shaft 2 is unbalanced in the drive state, and there is a risk of damage to the bearing and the output shaft of the motor due to the occurrence of vibrations and the like. The problem of loud sounds has been pointed out.

In order to solve this problem, a balancer 6 having a large diameter portion 6a and a small diameter portion 6b as shown in FIG. 10 is used. Specifically, by disposing the large-diameter portion 6a at both ends of the eccentric portion 2a in the direction opposite to the eccentric direction, the centrifugal force difference between the large-diameter portion 6a and the small-diameter portion 6b can be utilized to rotate. It is described that the dynamic imbalance during driving of the shaft 2 can be corrected.
Japanese Utility Model Publication No. 5-83372

  In the plunger drive structure configured as described above, the rotary shaft 2, the inner ring 3a, and the balancer 6 rotate integrally, but the outer ring 3b is fixed, so that frictional resistance is generated at the contact portion between the wall surface of the balancer 6 and the end surface of the outer ring 3b. . This frictional resistance may cause abnormal noise or vibration when the oil pump 11 is driven.

  Here, the wall surface of the balancer 6 is not subjected to surface finishing such as grinding, and the end surface of the outer ring 3b serves as a reference surface at the time of processing. Even if a scratch occurs, it is left as it is. As a result, the surface roughness of the contact surface is rough, which is considered to contribute to an increase in frictional resistance.

  Accordingly, an object of the present invention is to provide a plunger drive structure that reduces rotational resistance at a contact portion between a bearing and a balancer and suppresses abnormal noise and vibration during driving.

  A plunger drive structure according to the present invention includes a rotary shaft having an eccentric portion, an outer ring, and a plurality of rollers disposed along a raceway surface of the outer ring, and a roller bearing that supports the eccentric portion, and a roller bearing of the rotary shaft. A balancer disposed at an adjacent position, and a plunger that abuts on the outer ring and reciprocates by rotation of the rotating shaft are provided. And the surface roughness of the end surface facing the balancer of the outer ring is Rz ≦ 0.8 μm, and the surface roughness of the wall surface facing the outer ring of the balancer is Rz ≦ 3.2 μm.

  As described above, the rotational resistance during driving can be reduced by setting the surface roughness between the end face of the outer ring and the wall surface of the balancer that are in contact with each other to a predetermined value or less. As a result, a plunger drive structure that suppresses abnormal noise and vibration can be obtained. In the present specification, “Rz” refers to surface roughness based on ten-point average roughness.

  Preferably, the end surface of the outer ring facing the balancer is lapped. Preferably, the wall surface facing the outer ring of the balancer is barrel-finished. Thereby, it becomes possible to make the surface roughness of a contact surface below a predetermined value.

  In this specification, “lapping” refers to a processing method that finishes the surface with high precision by sliding the product on a lapping machine covered with a processing liquid mixed with abrasive grains while applying pressure to the product. And In this specification, “barrel finishing” refers to a polishing method in which a workpiece is placed in a barrel-shaped container together with particulate abrasives and a compound, and the barrel-shaped container is rotated and moved up and down. To do.

  According to the present invention, the end surface of the outer ring and the wall surface of the balancer that are in contact with each other are smoothed, so that the rotational resistance during driving can be reduced, and a plunger drive structure that suppresses abnormal noise and vibration can be obtained.

  With reference to FIGS. 1-3, the plunger drive structure for oil pumps based on one Embodiment of this invention is demonstrated.

  As shown in FIG. 1, the oil pump 11 is in contact with a rotating shaft 12 having an eccentric portion 12 a, a needle roller bearing 13 that supports the eccentric portion 12 a of the rotating shaft 12, and an outer ring of the needle roller bearing 13. A tappet 14 arranged radially, a plunger 15 arranged on the tappet 14 and reciprocatingly driven by rotation of the rotary shaft 12, and a balancer 16 arranged at both ends of the eccentric portion 12a are provided.

  As shown in FIG. 2, the needle roller bearing 13 includes an inner ring 13a, an outer ring 13b, a plurality of needle rollers 13c disposed between the inner ring 13a and the outer ring 13b, and a cage that holds the needle rollers 13c. 13d. Or the needle roller bearing 13 of the type which does not have the inner ring | wheel 13a and the needle roller 13c is arrange | positioned along the track surface of the outer ring | wheel 13b may be sufficient.

  As shown in FIG. 3, the balancer 16 has a large diameter portion 16a and a small diameter portion 16b, and the outer diameter contour line 16c intersects the circumscribed circle of the roller 13c. When the balancer 16 is arranged with the large-diameter portion 16a facing away from the eccentric direction as shown in FIG. 1, the rolling space of the roller 13c can be projected through the balancer 16 from the axial direction.

  The oil pump 11 can be miniaturized by using the needle roller bearing 13 having a small radial thickness as a bearing for supporting the eccentric portion 12a. At the same time, since the balancer 16 as shown in FIG. 3 does not hinder the flow of the lubricant supplied to the needle roller bearing 13, a plunger drive structure with excellent lubricity can be obtained.

  In the oil pump 11 configured as described above, the surface roughness is set to Rz ≦ 0.8 by lapping the end face of the outer ring 13 b facing the balancer 36. Further, the wall roughness of the balancer 36 facing the outer ring 13b is barrel-finished so that the surface roughness is Rz ≦ 3.2. At this time, attention should be paid not to leave any protruding scratches.

  As described above, the rotational resistance during driving can be reduced by smoothing the end surface of the outer ring 13b and the wall surface of the balancer 36 that are in contact with the oil pump 11 during driving. As a result, a plunger drive structure that suppresses abnormal noise and vibration can be obtained.

  Further, a balancer 36 shown in FIG. 4 may be used as a balancer used in the oil pump 11 described above. The balancer 36 has a large-diameter portion 36a and a small-diameter portion 36b, and a hatched portion in the drawing is cut so that the outer contour line of the small-diameter portion 36b is located inside the outer ring 13b. Thereby, the rotational resistance of the outer ring 13b and the balancer 36 when the oil pump 11 is driven can be reduced.

  In the above-described embodiment, an example in which the large-diameter portion 16a and the small-diameter portion 16b are provided and the central portion of the arc of the small-diameter portion 16b is cut is shown. You may provide a through-hole in a wall surface.

  For example, a large through hole 46a may be provided like the balancer 46 shown in FIG. 5A, or a plurality of small through holes 56a may be provided like the balancer 56 shown in FIG. 5B. In this case, the lubricant can be supplied to the bearing through the through holes 46a and 56a, and the size and number of the through holes 46a and 56a can be provided without providing the balancers 46 and 56 with a small diameter portion and a large diameter portion. It becomes possible to adjust the magnitude of the centrifugal force.

  Next, an oil pump plunger drive structure according to another embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 6, the oil pump 21 includes a rotating shaft 22, a needle roller bearing 23 that supports the rotating shaft 22, tappets 24 that are arranged radially in contact with the outer ring of the needle roller bearing 23, A plunger 25 is disposed on the tappet 24 and reciprocates by rotation of the rotating shaft 22, and a balancer 26 as shown in FIGS. 3 to 5 is provided at both ends of the needle roller bearing 23.

  Further, as shown in FIG. 7, the needle roller bearing 23 includes a plurality of eccentric inner rings 23a, outer rings 23b, eccentric inner rings 23a, and outer rings 23b that are different in thickness in the radial direction in the circumferential direction. A needle roller 23c and a cage 23d for holding the needle roller 23c are provided.

  Since the needle roller bearing 23 has the eccentric inner ring 23a, it is not necessary to provide an eccentric portion on the rotating shaft 22. As a result, in addition to the effects obtained in the embodiment shown in FIGS. 1 and 2, the manufacturing cost of the rotating shaft 22 can be reduced.

  The needle roller bearings 13 and 23 as shown in FIGS. 2 and 7 have the cages 13d and 23d for holding the needle rollers 13c and 23c, but are not limited thereto, and have the cages 13d and 23d. Alternatively, it may be a full roller bearing in which the adjacent needle rollers 13c and 23c contact each other. Since the load capacity of the needle roller bearings 13 and 23 increases as the number of needle rollers 13c and 23c accommodated, the load bearing capacity can be increased by using a full roller bearing that accommodates the needle rollers 13c and 23c as much as possible. Can be obtained.

  In each of the above embodiments, an example in which a needle roller bearing is used as a bearing that supports the eccentric portion is shown. However, the present invention is not limited to this, and any roller bearing that requires supply of lubricating oil from the outside is shown. By applying to the above, the same effect can be expected.

  Moreover, in the said embodiment, although the example which applied the balancer as shown in FIGS. 3-5 to the plunger drive structure of the oil pump used for a brake device for motor vehicles etc. was shown, it is not restricted to this, diesel The present invention can also be applied to a plunger drive structure for an engine fuel pump.

  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 present invention is advantageously used in a plunger drive structure for an oil pump.

It is a figure which shows the plunger drive structure for oil pumps concerning one Embodiment of this invention. It is a figure which shows the needle roller bearing used for FIG. It is a figure which shows the balancer used for FIG. It is a figure which shows other embodiment of a balancer. It is a figure which shows other embodiment of a balancer. It is a figure which shows the plunger drive structure for oil pumps which concerns on other embodiment of this invention. It is a figure which shows the needle roller bearing used for FIG. It is a figure which shows the plunger drive structure for the conventional oil pump. It is a figure which shows the ball bearing used for FIG. It is a figure which shows the balancer used for FIG.

Explanation of symbols

  1,11,21 Oil pump, 2,12,22 Rotating shaft, 2a, 12a Eccentric part, 3 Ball bearing, 4 Outer ring, 5, 14, 24 Tappet, 6, 15, 25 Plunger, 13, 23 Needle roller bearing 3a, 13a, 23a Inner ring, 3b, 13b, 23b Outer ring, 3c ball, 13c, 23c Needle roller, 3d, 13d, 23d Cage, 3e Sealing seal, 6, 16, 26, 36, 46, 56 Balancer, 6a, 16a, 36a Large diameter part, 6b, 16b, 36b Small diameter part, 16c Outer diameter outline, 46a, 56a Through hole.

Claims (3)

A rotating shaft having an eccentric part,
A roller bearing comprising an outer ring and a plurality of rollers disposed along a raceway surface of the outer ring, and supporting the eccentric portion;
A balancer disposed at a position adjacent to the roller bearing of the rotating shaft, and a plunger that contacts the outer ring and reciprocates by rotation of the rotating shaft;
The surface roughness of the end face of the outer ring facing the balancer is Rz ≦ 0.8 μm,
The plunger driving structure, wherein the surface roughness of the wall surface of the balancer facing the outer ring is Rz ≦ 3.2 μm.   The plunger drive structure according to claim 1, wherein an end surface of the outer ring facing the balancer is lapped. The plunger drive structure according to claim 1 or 2, wherein a wall surface of the balancer facing the outer ring is barrel-finished.

Images