Specification

TECHNICAL FIELD

The present utility model belongs to the technical field of bearing lubrication, and in particular, to a transmission structure allowing a rolling bearing employed therein to be lubricated easily.

BACKGROUND

On the market of vehicles, there has been a large number of eAxle power assembly systems in which otherwise independent components of a power assembly, i.e., a motor, an inverter, various transmission components, etc. are integrated into compact units. The eAxle may be mounted in a wide variety of vehicles on the market, such as a gas-electric hybrid vehicle, an electric vehicle, a small vehicle, an SUV, or even a light truck. For a heavy-duty eAxle power assembly system, a problem is how to ensure good lubrication of a rolling bearing employed therein, and another problem is how to discharge lubricating oil in a timely manner so as to avoid the risk of possible bush-burning and journal-sticking caused by raised oil temperature.

Currently, in order to perform lubrication operation on a rolling bearing operating at a high speed in a system structure, a direct injection nozzle typically needs to be designed to be in a corresponding position inside a structural housing so as to inject oil to perform lubrication. In this case, the design is relatively difficult due to that the design of the nozzle needs to be adapted to mounting dimensions in the structural housing so that the profile is complex and the implementation is more difficult, thereby increasing the manufacturing costs. In cases of a compact structure and limited space, it is even impossible to use the above-described direct injection nozzle to inject oil to perform lubrication. In addition, the above-described design cannot ensure heat dissipation performed on a bearing, and particularly, it is impossible to discharge high-temperature lubricating oil out of a rolling bearing in a timely manner, so that the above-described risk of bush-burning and journal-sticking still exists.

SUMMARY

An objective of the present utility model is to provide a transmission structure, so that a rolling bearing employed therein, particularly a needle bearing employed in an eAxle power assembly system of a vehicle, is easily lubricated, thereby overcoming the above-described at least one defect in the prior art.

According to an aspect of the present utility model, provided is a transmission structure, comprising a rotatable core shaft and at least one rolling bearing sleeved on the core shaft, wherein the core shaft is provided with a hollow lubricating oil channel extending axially, one end of the lubricating oil channel serving as an oil inlet via which lubricating oil is injected, the core shaft being further provided with an oil discharging channel extending radially from an inner peripheral surface of the lubricating oil channel to an outer peripheral surface of the core shaft, and an oil discharging hole of the oil discharging channel formed on the outer peripheral surface of the core shaft facing the corresponding rolling bearing.

Preferably, based on the number of the rolling bearings, the oil discharging channels provided on the core shaft are divided into a corresponding number of groups, and rolling bodies arranged in rows are provided in the rolling bearing, based on the number of rows of rolling bodies arranged in each rolling bearing the group of oil discharging channels corresponding to the rolling bearing being divided into a corresponding number of subgroups. Preferably, each sub-group is provided with at least two oil discharging channels, and the at least two oil discharging channels are oriented to be distributed evenly in a circumferential direction of the core shaft.

Preferably, the oil discharging channels in each sub-group are oriented relative to the oil discharging channels in an adjacent sub-group so as to be mutually evenly staggered so that projections of the group of oil discharging channels corresponding to each rolling bearing in a plane perpendicular to an axial direction of the core shaft are distributed evenly in the circumferential direction of the core shaft.

Preferably, the outer peripheral surface of the core shaft is provided with a lubricating oil groove extending circumferentially, and the oil discharging hole of the oil discharging channel formed on the outer peripheral surface of the core shaft is located in the corresponding lubricating oil groove.

Preferably, the rolling bearing comprises an inner ring, and the inner ring is provided with a hole aligned with the corresponding lubricating oil groove.

Preferably, the transmission structure further comprises a transmission component sleeved on each rolling bearing, wherein the transmission component has an axial opening for sleeving on the rolling bearing, and the transmission component is provided with an oil discharging groove on an axial end surface thereof and at the axial opening.

Preferably, two oil discharging grooves are provided on the end surface, and the oil discharging grooves are arranged in parallel with each other, and offset by a certain distance relative to the center of the end surface.

Alternatively, at least one oil discharging groove is provided on the end surface, an extension line of each oil discharging groove intersects at the center of the end surface, and the oil discharging groove is distributed evenly in a circumferential direction of the transmission component. Preferably, the transmission structure is used for an eAxle power assembly system of a vehicle, wherein the rolling bearing is a needle bearing, and the lubricating oil is pressure oil.

According to the transmission structure of the present utility model, it can be ensured that good lubrication and heat dissipation can be performed on the rolling bearing, thereby elongating the service life of the bearing.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of the present utility model can be more fully understood from the following detailed description provided with reference to the accompanying drawings. In the accompanying drawings:

FIG. 1 shows a schematic sectional view of an overall structure according to an embodiment of the present utility model;

FIG. 2 shows a sectional view acquired along line A-A in FIG. 1 , and also shows a diagram of projections of transmission components on this section viewed from a right viewing angle in FIG. 1 ;

FIG. 3 shows a perspective view of a core shaft and an enlarged view of a portion (the portion in circle B) thereof according to an embodiment of the present utility model; and

FIG. 4 shows a perspective view of a transmission component in the form of a gear according to an embodiment of the present utility model.

In the accompanying drawings of the present application, features having the same structures or similar functions are denoted by the same reference signs. It should be noted that the components in the accompanying drawings are not necessarily drawn to scale with respect to each other, and this is merely for the purpose of clear illustration instead of limiting. DETAILED DESCRIPTION

Various aspects and features of the present utility model are explained and illustrated in more detail below with reference to the accompanying drawings. In the description of the present utility model, it should be understood that terms, such as "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," etc., related to indication of directional or positional relationships are merely intended for easy description of the present utility model and to simplify description instead of indicating or implying that an indicated device or component necessarily has a certain orientation or is configured and operated in a certain orientation, and thus cannot be construed as limiting the present utility model.

FIG. 1 shows a schematic sectional view of an overall structure according to an embodiment of the present utility model. In this embodiment, lubrication performed for a needle bearing employed in an eAxle power assembly system of a vehicle is particularly used as an example to explain and illustrate relevant operating principles thereof. However, it can be understood that the same or similar structure can also be applied to other scenarios as desired so as to lubricate other types of rolling bearings. Referring specifically to FIG. 1 , a transmission structure in this embodiment generally includes a rotatable core shaft 1 , at least one rolling bearing sleeved on the core shaft 1 , and a transmission component (which is, for example, a gear 3 in this embodiment). In this embodiment, the rolling bearings are needle bearings 2a to 2d, and are sleeved in different axial positions on the core shaft in sequence, and the corresponding gear 3 is sleeved on each needle bearing. The above-described components are mounted as a whole in a housing of the eAxle power assembly system. The core shaft 1 is provided with a hollow lubricating oil channel 11 extending axially. One end (on the left side as shown in FIG. 1) of the lubricating oil channel 11 may serve as an oil inlet 12 via which lubricating oil (the lubricating oil is pressure oil in an application environment of this embodiment) is injected. After being injected into the lubricating oil channel 11 via the oil inlet 12, the lubricating oil under the action of pressure can reach the other end (on the right side as shown in FIG. 1) of the lubricating oil channel 11 . It should be noted here that although the drawing shows that the other end of the lubricating oil channel 11 is also provided with an opening serving as an oil outlet, this is not necessary in practice. In other words, the end of the lubricating oil channel 11 opposite the oil inlet may also be configured to be a closed end, or be closed by a component such as an end cap as desired. In this case, the lubricating oil injected into the lubricating oil channel 11 is discharged from the lubricating oil channel 11 via only an oil discharging channel as described in detail below.

Further referring to FIG. 1 to FIG. 3, the core shaft 1 is further provided with an oil discharging channel 13 extending radially from an inner peripheral surface of the lubricating oil channel 11 to an outer peripheral surface of the core shaft. An oil discharging hole 14 of each oil discharging channel 13 formed on the outer peripheral surface of the core shaft faces the corresponding needle bearing. In particular, each oil discharging hole is aligned with a rolling body in the form of a roller in the corresponding needle bearing. In this case, during operation, when the lubricating oil is injected, via the oil inlet 12, into the lubricating oil channel 11 formed inside the core shaft, as the core shaft 1 rotates at a high speed during the operation, the lubricating oil staying in the lubricating oil channel 11 is thrown, under the action of centrifugal force, out of the corresponding oil discharging hole 14 via the respective oil discharging channel 13 so as to reach the roller of the needle bearing corresponding thereto, thereby lubricating the corresponding needle bearing.

Details about specific configurations of each oil discharging channel on the core shaft and the correspondence between the oil discharging channel and the needle bearing are further explained below with reference to the accompanying drawings. Referring to FIG. 1 , it can be clearly seen that four needle bearings 2a, 2b, 2c, and 2d are sleeved in sequence in an axial direction of the core shaft from the left side to the right side in the drawing. Correspondingly, based on the number of needle bearings sleeved on the core shaft, the oil discharging channels provided on the core shaft are similarly correspondingly divided into four groups from left to right in the axial direction of the core shaft. The leftmost first group of oil discharging channels 13 is used as an example. It can be seen that in a region corresponding to the first needle bearing 2a, the group of oil discharging channels includes four oil discharging channels in total. The four oil discharging channels are further divided into two subgroups. Each sub-group includes two oil discharging channels 13 (the two oil discharging channels in one sub-group (i.e., a first sub-group) are shown in the section shown in FIG. 1 , but the two oil discharging channels in the other sub-group (i.e., a second sub-group) are perpendicular to the section shown in FIG. 1 , and are therefore not visible in this drawing) aligned with the rollers provided in the first needle bearing 2a. In consideration of maintaining dynamic balance of the core shaft during rotation, in addition to that the oil discharging channels in each sub-group need to be oriented to be distributed evenly in a circumferential direction of the core shaft, it also needs to be ensured that the oil discharging channels of the sub-groups are configured to be mutually evenly staggered. In particular, in the first group of four oil discharging channels corresponding to the needle bearing 2a, the two oil discharging channels in the first sub-group are oriented by 180 degrees relative to each other so as to be distributed evenly in the circumferential direction of the core shaft. Similarly, the two oil discharging channels in the second sub-group are also oriented by 180 degrees relative to each other so as to be distributed evenly in the circumferential direction of the core shaft. Further, as can be seen with reference to the sectional view in FIG. 1 , the oil discharging channels in the first sub-group and the oil discharging channels in the second sub-group are staggered by 90 degrees relative to each other in the circumferential direction of the core shaft, thereby ensuring that when viewed in the same viewing angle of the sectional view in FIG. 2, projections of the totally four oil discharging channels in the first group of oil discharging channels in a plane perpendicular to the axial direction of the core shaft are also distributed evenly in the entire circumferential 360-degree direction of the core shaft. As can be seen with reference to FIG. 1 , this embodiment shows that second to fourth groups of oil discharging channels corresponding to the second needle bearing 2b to the fourth needle bearing 2d are each designed to be divided into two sub-groups. Therefore, arrangement of the respective groups of oil discharging channels is similar to that of the first group of oil discharging channels, and details will not be described herein again.

It should be noted here that although in the above-described embodiment the group of oil discharging channels corresponding to each needle bearing is divided into two sub-groups, totally four channels, the number of oil discharging channels and grouping can vary according to actual requirements. In particular, in each needle bearing shown in FIG. 1 , the rolling bodies in the form of rollers are arranged in two rows (a gap S between the two rows of rollers spaced apart from each other is shown in the section in FIG. 1). In order to ensure that each row of rollers can be sufficiently lubricated, the group oil discharging channels corresponding to each needle bearing is correspondingly divided into two subgroups as described above, and the lubricating oil discharged from each sub-group of oil discharging channels is used to lubricate the corresponding row of rollers. It can be expected that, based on the number of rows of rollers arranged in each needle bearing, the group of oil discharging channels corresponding to this needle bearing can be divided into more than or less than two sub-groups. For example, for a needle bearing having a single row of rollers, only one sub-group of oil discharging channels may be configured to correspond to the needle bearing. The number of oil discharging channels depends on parameters such as a rotational speed of the core shaft, oil injection pressure at the oil inlet, the amount of discharged lubricating oil, etc. As described above, in order to ensure the dynamic balance of the core shaft rotating at a high speed, the oil discharging channels in this group are oriented so as to be distributed evenly in the circumferential direction of the core shaft. As previously described, in the case that only two oil discharging channels are provided, the oil discharging channels are oriented by 180 degrees relative to each other in the circumferential direction. In the case that three oil discharging channels are provided, the oil discharging channels are oriented so as to form an angle of 120 degrees pairwise in the circumferential direction, and so on. Correspondingly, for a needle bearing having more (e.g., three) rows of rollers, the entire group of oil discharging channels corresponding to the needle bearing is divided into a corresponding number of sub-groups, i.e., three sub-groups. As a possible arrangement, each sub-group may be configured to include two oil discharging channels, and the two oil discharging channels in the same subgroup are oriented by 180 degrees relative to each other in the circumferential direction. In addition, the oil discharging channels of adjacent sub-groups are staggered evenly by 60 degrees in the circumferential direction so as to ensure that projections of the totally six oil discharging channels in the entire group of oil discharging channels corresponding to the needle bearing in the plane perpendicular to the axial direction of the core shaft are distributed evenly in the entire circumferential 360-degree direction.

Further, referring to FIG. 3, depending on the structure of the needle bearing (particularly in the case that the needle bearing is provided with an inner ring), the outer peripheral surface of the core shaft 1 is further provided with a lubricating oil groove 15 extending circumferentially, so that the oil discharging hole 14 of the oil discharging channel 13 formed on the outer peripheral surface of the core shaft is located in the corresponding lubricating oil groove. The leftmost needle bearing 2a and the rightmost needle bearing 2d in FIG. 1 are used as an example. In the case that assembly is completed, the inner ring 21 is located between the rolling body (in the form of the roller) of the needle bearing 2a and the outer peripheral surface of the core shaft 1 . In this case, the lubricating oil thrown out of the oil discharging hole 14 via the oil discharging channel 13 cannot contact the roller at the earliest time to lubricate the same. Correspondingly, the lubricating oil groove 15 provided on the outer peripheral surface of the core shaft has the function of collecting the oil. That is, the lubricating oil thrown out by means of centrifugal force enters and occupies space of the entire lubricating oil groove 15 first, and meanwhile, the lubricating oil in the lubricating oil groove 15 is further guided to the roller by means of a hole 211 provided on the inner ring 21 of the bearing, so as to perform lubrication. Although the sectional views shown in FIG. 1 and FIG. 2 show that the hole 211 provided on the inner ring 21 of the bearing is aligned with the oil discharging hole 14 of the oil discharging channel 13 formed on the outer peripheral surface of the core shaft, it can be understood by those skilled in the art that depending on gears provided in the eAxle power assembly system, rotation of the inner ring 21 of the bearing is not necessarily synchronized with rotation of the core shaft 1 at all times. That is, the hole 211 is not necessarily aligned with the oil discharging hole 14 at different times. In actual configurations, as long as the hole 211 provided on the inner ring of the bearing is aligned with the lubricating oil groove 15, it can be ensured that the lubricating oil collected in the lubricating oil groove can be efficiently guided by the hole provided on the inner ring of the bearing to the roller so as to facilitate lubrication. In contrast to the above-described needle bearings 2a and 2d provided with the inner rings 21 , the two needle bearings 2b and 2c located in intermediate positions of the core shaft shown in FIG. 1 are not provided with any inner ring. As shown in the drawing, the lubricating oil thrown out of the oil discharging hole via the oil discharging channel can contact the roller directly to lubricate the same, so that the outer peripheral surface of the core shaft corresponding thereto does not need to be further provided with any lubricating oil groove to collect the oil. That is, the outer peripheral surface of this part of the core shaft is a smooth structure. As shown in FIG. 3, in addition to the above-described region provided with the lubricating oil groove and the smooth region on the outer peripheral surface of the core shaft, a flange 16 for separating adjacent needle bearings from each other or a spline 17 for connection to another transmission component can also be provided on the outer peripheral surface of the core shaft according to structural configuration requirements of the power assembly system. By means of the above-described improvement to the structure of the core shaft in the transmission structure, in particular by means of the provision of the hollow lubricating oil channel inside the core shaft and the provision of the oil discharging channel extending radially from the inner peripheral surface of the lubricating oil channel to the outer peripheral surface of the core shaft and corresponding to the rolling bearing sleeved on the outer peripheral surface of the core shaft, adaptation to mounting dimensions of the structural housing is not required, thereby ensuring the lubrication effect of the rolling bearing in cases of a compact structure and limited space. Particularly in the case that a plurality of rolling bearings need to be lubricated, a direct injection nozzle for injecting oil to perform lubrication does not need to be designed to be in a corresponding position inside the structural housing, thereby simplifying overall structural design and reducing manufacturing costs.

Further, in addition to that the lubricating oil needs to be conveyed efficiently to the rolling bearing to improve lubrication, the lubricating oil also needs to be discharged out of the rolling bearing in a timely manner so as to avoid the risk of bush-burning and journal-sticking caused by severely raised oil temperature. To this end, structural improvement is performed for the transmission component sleeved on the rolling bearing in the present application. Referring to FIG. 4, an example of the transmission component employed in the present application is the gear 3. The gear 3 has an axial opening 31 for sleeving on the above-described needle bearing. The gear 3 is provided with an oil discharging groove 33 on an axial end surface 32 thereof and at the axial opening 31 . The oil discharging groove is parallel with a radial direction, and extends outwards. Further referring to FIG. 1 , the direction of the arrow therein indicates a travel path of the lubricating oil in the entire transmission structure. It can be seen that after being injected into the lubricating oil channel 11 via the oil inlet 12, the lubricating oil first travels axially under the action of pressure to pass through the oil discharging channel 11 , meanwhile travels under the action of centrifugal force to pass through each oil discharging channel 13, and is thrown out via the oil discharging hole 14 to the needle bearing so as to perform lubrication. During the lubrication, more lubricating oil accumulates on a lubricated surface of the needle bearing, and the temperature thereof rises. Redundant lubricating oil on surfaces of the needle bearing and the transmission gear contacting each other moves in the axial direction and a direction opposite thereto so as to reach two axial end surfaces of the gear 3, so that the lubricating oil of the raised temperature is discharged by means of the provided oil discharging groove 33. The discharged lubricating oil may be recovered in other positions (not shown) in the housing, and be recycled after being cooled by means of an appropriate method. In an embodiment shown in FIG. 4, two oil discharging grooves 33 substantially parallel with each other are provided in each end surface of the gear. In this case, an extension line of the oil discharging groove does not pass through the center of the end surface of the gear, and is offset by a certain distance relative to the center of the end surface of the gear. With respect to the arrangement of the oil discharging groove, those skilled in the art can also conceive of providing only one oil discharging groove and configuring the extension line thereof to pass through the center of the gear so as to ensure that the oil discharging groove guides the lubricating oil radially. Alternatively, two oil discharging grooves may be provided. The two oil discharging grooves are oriented to be perpendicular to each other, and extension lines thereof are caused to intersect at the center of the end surface of the gear. In this case, viewed in the viewing angle perpendicular to the end surface of the gear, the oil discharging grooves are arranged to be substantially in the form of a cross. Certainly, in the case that mating between the transmission component in the form of a gear and the rolling bearing is not affected, more oil discharging grooves can be provided so that more heat can be carried away as the lubricating oil is discharged, thereby increasing the overall heat dissipation efficiency of the bearing.

Specific embodiments of the present application are described in detail above, but the specific embodiments are provided merely for the purpose of explanation, and should not be construed as limiting the scope of the present application. Further, it should be apparent to those skilled in the art that the embodiments described in the present specification may be used in combination with each other, and various components of the present utility model may be combined arbitrarily, unless such combination violates the objective of the present utility model or cannot be achieved. The present utility model in the broader sense thereof is therefore not limited to the specific details, representative structures, and exemplary examples that are shown and described.