GB2545418A

GB2545418A - Connecting rod

Info

Publication number: GB2545418A
Application number: GB1521940.5A
Authority: GB
Inventors: Meyer Franziska; Engelen Philip; Baubet Yannick
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 2015-12-14
Filing date: 2015-12-14
Publication date: 2017-06-21
Also published as: GB201521940D0

Abstract

The connecting rod 1 comprises at least one bearing 2 with a bearing axis (a) which is arranged in a ring section 3 of the connecting rod. A recess 4 and a lubrication channel are provided for supplying the bearing with a lubricant. The recess 4 is arranged in a radially and axially outer region of the ring section. The lubrication channel extends from the recess to a bore 6 of the ring section to establish a fluidic connection between the recess and the bore. A recess may be located on each axial side of the ring section. The channel may be a through hole that extends from the recess to the bore.

Description

Connecting Rod

Technical Field

The invention relates to a connecting rod comprising at least one bearing with a bearing axis which is arranged in a bore of a ring section of the connecting rod, wherein means are provided for supplying the bearing with a lubricant.

Background

Connecting rods of the generic kind are well known in the art. They are used specifically in combustion engines for supporting the crankshaft. Often, journal bearings are used for supporting the connecting rod at the crankshaft; but also roller bearings are employed for this purpose.

The lubrication of the connecting rod bearing is typically achieved via lubrication channels extending from the crankshaft. The complexity of manufacturing the lubrication channels inside the crankshaft makes this a relatively expensive procedure. Furthermore, the required routing of the lubrication from stationary to rotary components adds to the complexity of the system.

Specifically, in 4-stroke engines (which is a major application area for the present invention as well), the current design of the connecting rod is based on the use of journal bearings with the oil supply originating from the crankshaft as mentioned. Since journal bearings use high pressure oil, no alternative for supplying the high pressure lubrication oil has been found yet insofar.

However in the case of connecting rod roller bearings, alternative solutions are possible but presently not on hand.

Roller bearings in the connecting rod do not require high pressure and high volume lubrication oil - in distinction to journal bearings. With the reduction of lubricant needed from the engine oil pump, the pump can be downsized and the total energy needed in the system is therefore reduced. Advantages in manufacturing and in terms of costs can be obtained by removing a direct oil supply channel and using splashing oil from the surroundings for the lubrication of the roller bearings.

Pre-known solutions of the generic kind are shown in US 1 540 523 A, in CN 2811651 Y, in JP 05 304 187 B2 and in CN 203477045 U.

Current designs are not suitable to supply the bearing with a sufficient amount of lubricant when no oil pump is employed for this purpose.

Thus, it is an o b j e c t of the present invention to provide a connecting rod of the generic kind by which the lubrication of the bearing is facilitated. Specifically, a sufficient amount of lubricant should be supplied to the bearing without the need of a pump. Splashing oils should be effectively used to bring oil in a sufficient amount to the bearing components which have to be lubricated.

Summary of the invention A solution according to the invention is characterized in that the means for providing the lubricant comprise at least one recess which is arranged in a lateral region of the connecting rod, in a ring section of the connecting rod that serves as an outer ring of the bearing and at least one lubrication channel which extends from the recess to a bore of the ring section, to establish a fluidic connection between the recess and the bore.

Suitably, the recess is formed or machined in a radially and axially outer region of the ring section.

The bore can directly serve as the outer raceway for rollers of the bearing.

In some embodiments, the connecting rod comprises a first recess at a first axial side of the ring section and a corresponding first lubrication channel that extends between the ring section bore and the first recess. In other embodiments, the connecting rod further comprises a second recess at a second, opposite axial side of the ring section bore and a corresponding second lubrication channel that extends between the ring section bore and the second recess.

The at least one recess may have an arcuate shape seen in the direction of the bearing axis. Preferably, the at least one recess has a U-shaped form seen in the direction of the bearing axis. The opening of the lubrication channel may be located in the recess at a point on the recess surface that is closest to the bearing axis.

Preferably, the at least one lubrication channel enters the bore of the ring section, i.e. opens into outer raceway of the bearing, at a location where a cage of the bearing has no contact with the bore during regular operation of the bearing. In other words, the lubrication channel enters the bore after or beyond a contact area on the bore against which axially peripheral portions of the cage bear, i.e. said entry point of the lubrication channel into the bore is axially inward of the cage supporting surface. Since the surface for the cage support is thus continuous, cage life is optimized.

The at least one lubrication channel is preferably a through hole with a straight axis. In this case the axis of the channel can be arranged under an angle to a longitudinal direction of the connecting rod, which angle is between 1° and 89°, preferably between 30° and 60°. Of course the channel can also be arranged parallel to the longitudinal direction of the connecting rod.

Also, the at least one recess can have a bottom surface in a radial cross section which is arranged under an angle to the bearing axis which angle is between 1° and 20°.

Finally, the at least one recess can have a side surface in a radial cross section which is arranged under an angle to the longitudinal direction of the connecting rod, which angle is between 1° and 20°. The mentioned angle can also be beneficial with respect to the manufacturing process. But of course said surface can also be parallel to the longitudinal direction (i.e. with an angle of zero).

The recess is preferably arranged at a radially uppermost region of the ring section. This definition has to be understood under the condition that the connecting rod stands vertically upwards along its longitudinal direction, and the ring section serves as the outer ring for a lower, relatively larger bearing of the connecting rod.

The bearing can be a roller bearing, such as a needle roller bearing or a cylindrical roller bearing.

The connecting rod is preferably a connecting rod of a combustion engine, especially of a 4-stroke combustion engine.

Thus, the invention proposes an integrated lubrication channel in the connecting rod for the due supply of a lubricant to the bearing.

The invention provides an integrated lubrication channel and a kind of “funnel” for the lower connecting rod bearing. The function of the “funnel”, i.e. of the recess, is to collect oil from the surroundings; the function of the channel, is to direct the oil towards the lower connecting rod bearing.

Thus, the use of splashing oil, specifically in the region of the crankshaft, is enabled.

By using of a roller bearing in the connecting rod, the requirement of using high pressure lubrication for the bearing is removed. Therefore the lubrication is moved away from the crankshaft and positioned on the connecting rod. The supply of the oil to the connecting rod is collected from the surroundings.

The recess and lubrication channel are designed to have three main attributes: The collection (mostly during Bottom Dead Centre (BDC)), the retention and the guidance of the oil (during rotation from BDC back to BDC).

The recess can have a wide U-shape opening to collect the oil from the surroundings and guide it to the lubrication channel. In addition to a U-shape, the recess may also be angled towards the channel to retain and guide the oil towards the channel. Other shapes for the recess are, of course, possible; for example, V-shaped openings or elliptical shaped openings. It is also possible that the recess has a shape with a larger length (in circumferential direction of the ring section) internally than the circumferential length at the entrance to the recess.

Suitably, the lubrication channel is located at the lowest point of the recess to guide the oil onto the raceway of the bearing. The purpose of an angled design of the recess can be to deliver the oil closer to the middle of the bearing. As mentioned, the cage landings then retain full contact with the outer raceway on the ring section, which optimizes cage life. A further benefit is that a complex lubrication system in the crankshaft can be avoided. In addition, the required energy is reduced since splashing oil can be used for lubrication of the bearing instead of employing an oil pump for this purpose.

Brief description of the drawing

The drawings show an embodiment of the invention.

Fig. 1 shows a perspective view of a connecting rod of a combustion engine,

Fig. 2 shows the connecting rod according to figure 1 in a front view,

Fig. 3 shows the cross section A-A according to figure 2 and

Fig. 4 shows the detail “B” according to figure 3.

Detailed description of the invention

In the figures, a connecting rod 1 of a combustion engine is shown and some details of the same. In general, the connecting rod 1 has an upper ring section for an upper bearing and a lower ring section for a lower bearing, which will be mounted to a crankshaft. Here, the lower ring section and the lower bearing are of interest.

As can be seen in figure 1, a bearing 2 is arranged in a bore of the lower ring section 3. A smaller bearing (not shown) for the piston may be arranged in the upper ring section of the connecting rod. The upper and lower ring sections are connected by a beam portion that extends in a longitudinal direction L of the connecting rod 1.

The bearing 2 which is arranged in the bore of the lower ring section 3 is a roller bearing in the present case. As a roller bearing requires substantially less lubricant (oil) than a journal bearing, the present invention is primarily directed to the use of a roller bearing. In the figures, the rollers 9 of the bearing 2 are shown, as well as a cage 10 for holding the rollers 9.

The outer bearing ring of the bearing is established by the ring section 3, whereby the bore 6 (radially inner surface; see figure 3) serves as an outer raceway of the bearing 2. The inner bearing ring is established by a shaft section of the crankshaft on which the connecting rod is used (not depicted).

The cage 10 is designed to be guided at the bore 6 of the ring section 3. Axially peripheral portions of the cage, known as cage landings, bear against a contact area 13 on the bore 6 (see figure 4). A continuous contact area 13 is beneficial for a long lifetime of the cage 10.

The lower ring section 3 of the connecting rod 1 has a greater axial length than the beam portion. In figures 1 and 3, the axial extension of the ring section, relative to the beam portion, is designated with reference numeral 11. The axial length of the extension 11 depends on the length of the rollers 9 that are used in the bearings

To make sure that a sufficient amount of lubricant (oil) is fed into the rolling contact of the rollers 9, lubrication means 4, 5 are provided. Those means ensure that splashing oil is effectively guided into the rolling contact.

The means for providing the lubricant comprise a recess 4, which is arranged in each axial extension 11 of the lower ring section 3, as well as respective lubrication channels 5 which extend from the recess 4 to the bore 6 of the ring section 3; i.e. to the outer raceway of the bearing 2. Hereby, a fluidic connection between the recess 4 and the bore 6 is established. In other examples of a connecting rod according to the invention, a single recess and corresponding channel is provide at one side of the connecting rod.

An example of a specific geometry of the recess 4 and of the lubrication channel is shown in figures 2 and 4.

Here, it can be seen that the recess 4 has an arcuate shape 12; specifically it is U-shaped (see figure 2).

The axis b of the lubrication channel 5 (see figure 4) has an angle a relative to the longitudinal direction L of the connecting rod, which is about 45° in the depicted example. Preferably, the lubrication channel 5 opens into the bore 6 of the ring section 3 at a location that is axially inward of the cage contact areas 13. As a result, the contact areas 13 for the cage landings constitute a continuous surface, which optimises cage life. When the cage landings have a relatively large axial length, the angled axis of the lubrication channel 5 facilitates the location of the channel opening towards the axial centre of the bore. When the bearing 2 has a cage with relatively short landings, the channel 5 may, of course, have an axis that is essentially parallel to the longitudinal direction L.

The recess has a bottom surface 7 which may have an angle β relative to the bearing axis a. In the depicted example, the angle is about 5°. A side surface 8 of the recess 4 may also be angled relative to the longitudinal direction L. In the depicted example, the side surface 8 of the recess has an angle γ to the longitudinal direction L which is also about 5°. The angled surfaces may be beneficial in terms of guiding the lubrication oil to the opening of the lubrication channel 5.

By this design, a kind of funnel is formed by the recess 4 which collects splashing oil and guides it via the channel 5 to the rolling contact of the bearing 2. The recess 4 is thus suitably located on a radially upper portion of the lower ring section 3, so that oil may be retained within the recess. Additional measures for lubrication thereby become unnecessary.

Reference Numerals; 1 Connecting rod 2 Bearing 3 Lower ring section of connecting rod 4, 5 Means for supplying lubricant 4 Recess 5 Lubrication channel 6 Bore of lower ring section 7 Bottom surface of the recess 8 Side surface of the recess 9 Roller 10 Cage 11 Axial extension of the lower ring section 12 Arcuate shape 13 Contact area for the cage a Bearing axis b Axis of the bore L Longitudinal direction a Angle β Angle γ Angle

Claims

Patent Claims;

1. Connecting rod (1) comprising a bearing (2) having a bearing axis (a), wherein a ring section (3) of the connecting rod (1) has a bore (6) which serves as an outer raceway for rolling elements of the bearing (2), and wherein means (4, 5) are provided for supplying the bearing (2) with a lubricant, characterized in that the means for providing the lubricant comprise at least one recess (4) which is arranged at a radially and axially outer region of the ring section (3) and at least one lubrication channel (5) which extends from the recess (4) to the bore (6) of the ring section, to establish a fluidic connection between the recess (4) and the bore (6).

2. Connecting rod according to claim 1, characterized in that a recess (4) is arranged at each axial side of the ring section (3), and a lubrication channel (5) is provided which extends from each recess (4) to the bore (6) of the ring section (3).

3. Connecting rod according to claim 1 or 2, characterized in that the at least one recess (4) has an arcuate shape seen in the direction of the bearing axis (a).

4. Connecting rod according to claim 3, characterized in that the at least one recess (4) has a U-shaped form seen in the direction of the bearing axis (a).

5. Connecting rod according to one of claims 1 to 4, characterized in that the lubrication channel (5) is a through-hole that extends from the at least one recess (4) to the bore (6) of the ring section.

6. Connecting rod according to claim 5, characterized in that the lubrication channel (5) and the recess (4) meet at a location of the recess (4) which is radially closest to the bearing axis (a).

7. Connecting rod according to one of claims 1 to 6, characterized in that the lubrication channel (5) has a straight axis (b).

8. Connecting rod according to claim 7, characterized in that the axis (b) of the bore (5) is arranged under an angle (a) to a longitudinal direction (L) of the connecting rod (1), which angle is between 1° and 89°, preferably between 30° and 60°.

9. Connecting rod according to one of claims 1 to 8, characterized in that the bearing comprises a cage (10), axially outer portions of which bear against a contact area (13) on the bore (6) of the ring section (3), and in that the at least one lubrication channel (5) enters the bore (6) at a location that is axially inward of the contact area (13).

10. Connecting rod according to one of claims 1 to 9, characterized in that the at least one recess (4) has a bottom surface (7) in a radial cross section which is arranged under an angle (β) to the bearing axis (a), which angle is between 1° and 20°.

11. Connecting rod according to one of claims 1 to 10, characterized in that the at least one recess (4) has a side surface (8) in a radial cross section which is arranged under an angle (γ) to the longitudinal direction (L) of the connecting rod(l), which angle is between 1° and 20°.