RU2478842C1 - Shaft arrangement, and shaft supporting method - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention refers to the shaft that includes rotating shaft (4) that has hole (9) passing through it in longitudinal direction. In addition, the device includes bar (10) passing in longitudinal direction of shaft (4) through hole (9) from one end of shaft (4) to the other one. Bar (10) is provided on one end with radially directed supporting element (14). Supporting element (14) is located in axial direction after the end of shaft (4) and passes in radial direction beyond outer diameter of shaft (4) at the end. Supporting element has an axial inner surface with radially external part (142) and radially internal part (143). Radially external part (142) is offset in axial direction to shaft (4) relative to radially internal part (143). The invention also refers to the method of supporting shaft (4) by means of the above device.

EFFECT: implementation of the shaft supporting so that the problems occurring from various thermal expansion coefficients of the shaft and the support structure can be eliminated or minimised.

16 cl, 2 dwg

Description

Technical field

A first aspect of the present invention relates to a shaft device comprising a rotatable shaft that has an opening extending through it in its longitudinal direction.

The invention also relates to a bearing structure provided with such a shaft device, a gearbox having such a bearing structure, and a vehicle with such a gearbox.

State of the art

In many contexts, the shaft that requires support is made of a material different from the supporting structure, for example, the gearbox housing in which it is supported. The shaft is typically made of steel, and the surrounding supporting structure may be made of some other material, such as aluminum. The fact that the shaft and the supporting structure are made of different materials with different coefficients of thermal expansion creates a problem, especially if the materials are steel and aluminum. This is more specifically applicable to bearing designs. In the case of, for example, a gearbox in a large vehicle, the difference in thermal expansion between room temperature and operating temperature will be up to about 0.5 mm between the ends of the shaft. This leads to the problem of maintaining a clearance or preload, which was established at room temperature.

The problem of bearing clearance, which changes as a result of different thermal expansions of the shaft and supporting structure, is described, in particular, in publications WO 2008/005788, US 5325599 and US 5386630, but these descriptions are mainly related to measurements related to a single bearing and how is it installed. None of those descriptions indicate a complete solution.

An object of the present invention is to provide shaft support in such a way that problems arising from differing thermal expansion coefficients of the shaft and supporting structure are accordingly eliminated or at least reduced.

SUMMARY OF THE INVENTION

The first aspect of the invention is that this problem is solved by creating a shaft device of the type indicated in the introduction, which has the distinctive features that the shaft further comprises a shaft that extends in the longitudinal direction of the shaft through the hole from the first end of the shaft to the second end a shaft and which is provided at the first end with a radially directed supporting element located in the axial direction behind said first end and extending in the radial direction beyond the outer diameter of the shaft at the first end, and having an axial inner surface with a radially outer part and a radially inner part, the radially outer part being displaced axially towards the shaft relative to the radially inner part.

Thereby, the supporting element can easily be axially free from axial contact with the shaft end and the rotating parts of the bearing, while at the same time the outer ring of the bearing can be supported in the axial position, which coincides with the shaft end, or in the short axial position distance inward on the shaft.

A shaft arrangement made in this way allows the shaft to be supported without affecting temperature changes on bearing accuracy. The rod may be axially attached relative to the shaft at the second end of the shaft, thereby essentially maintaining the axial position of the support member relative to the shaft regardless of temperature changes. This, of course, implies that the shaft is made of a material with approximately the same coefficient of thermal expansion as the shaft material. Mostly the shaft and shaft will be made of the same material, for example steel. A shaft and a shaft made of the same material will maximize accuracy with respect to maintaining the relative axial position of the supporting member and the first end of the shaft.

If the shaft is supported in a bearing structure, which contains, in particular, an axial force absorbing rolling bearing at or near the first end of the shaft, the supporting element can act as an axial support for the stationary bearing ring. Since temperature changes do not affect the relative axial position of the supporting element and the shaft end, the accuracy of the bearing, i.e. the clearance or preload that has been installed, will not change. If instead the outer ring is inserted and receives its axial support from the surrounding supporting structure, its axial position relative to the shaft end will change with temperature and, therefore, will require compensating measures and adjustments.

Thus, the shaft device according to the invention eliminates the problems associated with such compensation measures, since the supporting element provides an axial supporting surface that is not affected by temperature changes. Therefore, according to the invention, the device facilitates supporting the shaft in a simple manner with optimal installation in a large temperature range. It also eliminates the need for other measures to establish a fixed bearing clearance.

Advantageously, although not necessarily, the hole passing through the shaft is round and is predominantly coaxial with the shaft. The rod is also predominantly round and should be aligned with the hole.

According to a preferred embodiment of the shaft device, the support element extends radially beyond the outer diameter of the shaft at a plurality of points distributed in the circumferential direction.

A support element made in this way enables axial support at a plurality of points distributed circumferentially on the outer ring of the rolling bearing, so that the absorption of force is distributed.

According to a further preferred embodiment, these points are distributed at mutually equal intervals in the circumferential direction.

The support for absorbing axial forces will thus be symmetrically evenly distributed, so that the force on the outer ring will be evenly distributed, and the risk of skewing of the outer ring will be eliminated.

According to a further preferred embodiment, the support element extends beyond the outer diameter around the entire circumference of the shaft.

In this way, the absorption of force will be distributed as evenly as possible, resulting in optimal work safety. For this, the support element may, for example, have a circular outer contour and have the form of a disk.

According to a further preferred embodiment, the supporting element is attached to the rod by fixing means arranged so that the axial position of the supporting element on the rod can be set.

The axial position of the support element relative to the shaft, therefore, can be adjusted so as to achieve optimum accuracy for axial support of the outer ring at the expected operating temperatures. The design also takes into account a certain amount of subsequent adjustment.

According to a further preferred embodiment, the fixing means comprises a threaded portion of the shaft and a nut.

Said axial positioning of the supporting element can thus be carried out simply and reliably.

According to a further preferred embodiment, the shaft is provided with a radial clearance in said hole.

Thus, the risk of contact between the shaft and the shaft, which can lead to friction losses, and the risk of operational malfunctions are prevented.

According to a further preferred embodiment, a shaft is provided at the second end of the shaft with a second radially directed supporting element located axially behind said second end and extending radially beyond the outer diameter of the shaft at the second end.

This embodiment also allows axial support of the same type to be provided for the axial force absorbing roller bearing at the second end of the shaft.

Since the supporting element is pushed to the corresponding outer ring of the rolling bearing at each end of the shaft, the axial distance between the outer rings will change in unison with changes in shaft length that arise from temperature changes, i.e. the axial distance is relatively fixed. The result is an easy-to-handle shaft assembly that can be installed in the supporting structure with guaranteed bearing accuracy. Advantageously, the supporting structure will have axial supporting surfaces that limit the possibility of axial outward movement of the corresponding supporting element.

According to a further preferred embodiment, the second support member is configured as described above for the first support member, in particular according to any of the preferred embodiments described above. The second support element will thus provide the same benefits. The supporting elements are advantageously designed in the same way, but alternatively they can be made according to mutually different embodiments.

According to a further preferred embodiment, the shaft is provided with axial locking means at the second end of the shaft to fix the axial position of the corresponding shaft end relative to the supporting structure.

This embodiment provides an alternative to the latter embodiment described above, and facilitates mounting of the shaft device at the first end of the shaft, since the first support ring will therefore not require special support to prevent axial outward movement.

The bearing structure according to the invention comprises both a shaft device according to the invention, in particular according to any of the preferred embodiments of the latter, and at least one first axial force absorbing rolling bearing with a ring that rotates with the shaft, the stationary ring and located between them rolling elements, the first supporting element being able to be pressed into a fixed ring, the axial mobility of which, therefore, is limited only by one side not part of a rolling bearing and on the other side of the first support member.

In this specification, an axial force absorbing rolling bearing means not only a bearing that absorbs only axial forces, but also a bearing that absorbs both axial and radial forces, for example, a tapered roller bearing.

According to a preferred embodiment of the bearing structure, it further comprises a second axial force absorbing rolling bearing for an axial force acting in a direction opposite to the axial force that the first rolling bearing is capable of absorbing, the second rolling bearing having a ring that rotates with the shaft, stationary the ring and the rolling elements located between them, so that the second supporting element is configured to be pressed into the stationary ring, axially the mobility of which, therefore, is limited only on one side by the rolling elements of the bearing and on the other side by a supporting element.

The gearbox according to the invention comprises a bearing structure according to the invention.

A vehicle according to the invention comprises a gearbox according to the invention.

The bearing structure, gearbox and vehicle of the invention provide the same advantages as the advantages of the shaft device and its preferred embodiments described above.

A second aspect of the invention is a shaft support method, which includes special measures in that

provide a hollow shaft,

pass the rod through the hole in the shaft,

provide support to the shaft with bearings, each of which contains a first axial force absorbing rolling bearing with a ring that rotates with the shaft, a stationary ring and rolling elements between them,

mounted on the rod at the first end of the shaft, the first supporting element containing an axial inner surface with a radially outer part and a radially inner part, and the radially outer part is displaced axially towards the shaft relative to the radially inner part,

provide a radially outer part of the first supporting element against a stationary ring against the rolling elements of the rolling bearing so that the axial mobility of the stationary ring is limited only on one side by the rolling elements of the bearing and on the other side by the first supporting element,

the shaft bearing is mounted in the supporting structure so that the supporting structure limits the axial mobility of the first supporting element.

According to preferred embodiments, the inventive method is applied using the shaft device according to the invention, in particular according to any of the preferred embodiments of the shaft device.

The invented method also provides the same advantages as indicated above for the shaft device and its preferred embodiments.

The invention will be explained below through a detailed description of examples of options for its implementation, given below with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 is a longitudinal section of part of a gearbox according to a first embodiment of the invention; and

2 is a corresponding section according to a second exemplary embodiment.

Detailed Description of Embodiments

Figure 1 is a longitudinal section of part of a gearbox according to the invention. The gearbox has a housing 1 constituting a supporting structure for the gearbox shafts. The gearbox in the example has a secondary shaft 2 and an intermediate shaft 4. The invention is described with reference to the intermediate shaft 4, which is provided with a shaft device and a bearing structure according to the invention. Other parts of the gearbox are, in principle, conventional and are not described in more detail here. The intermediate shaft 4, hereinafter referred to as the shaft 4, is provided with a number of gears 5 interacting with the secondary shaft 2.

The shaft 4 is supported by a first tapered roller bearing 7 at one end of the shaft 4 and a second tapered roller bearing 8 at the opposite end of the shaft 4. A concentric round hole 9 is located in the shaft 4 and passes through the entire length of the shaft 4. The rod 10 passes through the hole 9 with a small clearance in it so that contact with the shaft is prevented. The rod is attached at its end, which is left in the drawing, to part 11 of the end wall of the housing. The fastening is carried out by the end 13 of the rod 10 having a thread and screwed into the threaded hole in the end wall portion 11.

A supporting member 14 in the form of a circular disk 14 is attached to the right end of the shaft 10. The disk 14 has a central hole through which it is worn on the shaft 10 and tightly screwed through the nut 17 and the threaded end of the shaft 10.

The inner side of the radially outer portion 142 of the disk 14 is pressed against the stationary outer ring 71 of the bearing 7 by appropriately screwing the left end of the shaft 10 into the hole 12 in the end wall portion 11 and / or tightening the nut 17. Thus, the disk 14 maintains the bearing 7 to absorb axial forces that act to the right.

The support of the left end of the shaft 4 in this example has a conventional configuration in which the outer ring of the second bearing 8 abuts against the axial abutment surface of the end wall portion 11 to absorb axial forces that act to the left.

The housing 1 is made of aluminum, and the shaft 4 and the shaft 10 passing through it are made of steel. If the gearbox is heated to a temperature higher than that used in the state shown in Fig. 1, both the housing 1 and the shaft 4 and the shaft 10 will expand both in the radial and axial directions. Since the housing 1 is made of aluminum, it will expand to a greater extent than the shaft 4 and the shaft 10. In the radial direction, the quantities considered are so small that they do not cause any problems, while the difference in axial expansion can be up to several tenths of a millimeter.

When the housing 1 extends axially with respect to the shaft, the result is that the housing portion 21 in which the right bearing 7 is mounted moves to the right relative to the end of the shaft 4 and relative to the disk 14 attached to the shaft 10. Since the housing portion 21 does not have an axial thrust surface for the outer ring 71, the effect on the axial support of the bearing 7 is absent. It takes the form of a disk 14 and its position relative to the shaft does not change. Thus, there is no effect of the temperature difference on the clearances or preloaded bearings 7, 8.

As can be seen from the drawing, the disk 14 has a radially outer part 142 directed toward the outer ring of the bearing 71 and offset inward relative to the rest of the disk. The purpose of this is to create a clearance space between the disk 14 and the shaft and the rolling elements, respectively. An alternative possibility is to provide an intermediate ring between the outer ring 71 and the disk 14. A stronger displacement of the surface 142 of the intermediate ring over a significant axial extent will make it possible to locate the bearing 7 a little more on the shaft.

The second example of the embodiment shown in FIG. 2 differs from the embodiment in FIG. 1 with respect to the fastening of the rod and with respect to the disc part at the right end of the shaft, but otherwise is made in the same way.

In this example, the rod 10 is not attached to the end wall of the housing, and is also provided at its left end with a device of the same type as its right end. Thus, the rod is not fixed in the housing at the left end. Instead, a disk-shaped abutment member 14b 14b is attached to the shaft 10 by means of a threaded nut 17b.

Thus, the shaft 4, the shaft 10, the two disks 14, 14b and the bearings 7, 8 form an integral unit with a fixed space regardless of the temperature between the bearings 7, 8, so that the latter keep the settings unchanged.

At the left end of the shaft, the disk 14b is sandwiched between the outer bearing ring 81 and the axial supporting surface 110b of the housing end wall portion 11b. At the right end of the shaft, a thrust ring 18 is attached to the housing portion 21b to limit the movement of the disk 14 out of the shaft.

When the housing 1 expands axially relative to the shaft 4, the distance between the axial support surface 110b in the end wall portion 11b and the thrust ring 18 will increase by several tenths of a millimeter more than the distance between the disks 14, 14b. Thus, the corresponding axial clearance is formed, although it will not affect the preset bearings, which are held together by holding forces between the disks 14, 14b. Thus, the shaft is provided with some axial mobility, but this is acceptable from the point of view not covering the location of the bearings, which, of course, is not violated in itself. The axial force from the assembly is absorbed by the axial support surface 110b in the end wall part 11b or by the thrust ring 18 in the housing part 21b, depending on the direction in which the axial force acts.

Claims (16)

1. A shaft device comprising a rotatable shaft (4) that has a hole (9) extending through it in its longitudinal direction, the device further comprising a shaft (10) that extends in the longitudinal direction of the shaft (4) through the hole (9) from the first end of the shaft to the second end of the shaft and which has a radially directed support element (14) at the first end located axially behind the first end and extending radially beyond the outer diameter of the shaft (4) at the first end, different characterized in that the supporting element has an axial inner surface with a radially outer part (142) and a radially inner part (143), the radially outer part (142) being axially offset to the shaft (4) relative to the radially inner part (143). 2. The device according to claim 1, characterized in that the supporting element (14) extends radially beyond the outer diameter of the shaft (4) at a plurality of points distributed in the circumferential direction. 3. The device according to claim 2, characterized in that the plurality of points are distributed at mutually equal intervals in the circumferential direction. 4. The device according to claim 1, characterized in that the supporting element (14) extends radially beyond the outer diameter of the shaft (4) at the first end around the entire circumference of the shaft. 5. The device according to any one of claims 1 to 4, characterized in that the supporting element (14) is attached to the rod (10) by fixing means (17) located so as to enable the axial position of the supporting element (14) to be installed on the rod ( 10). 6. The device according to claim 5, characterized in that the fixing means (17) comprises a threaded portion of the shaft and a nut (17). 7. The device according to claim 1, characterized in that the rod (10) has a radial clearance in said hole (9). 8. The device according to claim 7, characterized in that the rod (10) has at the second end of the shaft a second radially directed supporting element (14b) located axially beyond the second end and extending radially beyond the outer diameter of the shaft (4) at the second end . 9. The device according to claim 8, characterized in that the second supporting element (14b) extends radially beyond the outer diameter of the shaft (4) at a plurality of points distributed in the circumferential direction, and the many points are distributed at mutually equal intervals in the circumferential direction, wherein the second supporting element (14b) is attached to the rod (10) by fixing means (17) arranged so as to enable the axial position of the supporting element (14) to be installed on the rod (10). 10. The device according to claim 1, characterized in that the rod (10) has at the second end of the shaft (4) means (12, 13) for fixing the axial position for fixing the axial position of the corresponding end of the rod (10) relative to the supporting structure (1). 11. Bearing design, characterized in that it comprises a shaft device according to any one of claims 1 to 10 and at least one first axial force absorbing rolling bearing (7) with a ring (72) that rotates with a shaft, a fixed ring (71) and rolling elements (73) located between them, so that the first supporting element (14) is capable of being pressed into the stationary ring (71), the axial mobility of which is therefore limited only on one side by the bearing element (73) and on the other side - first supporting element (14). 12. Bearing design, characterized in that it comprises a shaft device according to any one of claims 8 to 10 and at least one first axial force absorbing rolling bearing (7) with a ring (72) that rotates with a shaft, a fixed ring (71) and rolling elements (73) located between them, so that the first supporting element (14) is capable of being pressed into the stationary ring (71), the axial mobility of which is therefore limited only on one side by the bearing element (73) and on the other side - first supporting element (14), while the bearing structure further comprises a second axial force absorbing rolling bearing (8) for an axial force acting in a direction opposite to the axial force that the first rolling bearing (7) is capable of absorbing, and the second bearing (8 ) the rolling element has a ring (81) that rotates with the shaft (4), a stationary ring (82) and rolling elements (83) located between them, so that the second supporting element (14b) is capable of being pressed into the stationary ring (82), axial mobility which is therefore limited only on one side by the rolling elements (83) of the bearing and on the other side by the supporting element (14b). 13. A gearbox, characterized in that it comprises a bearing structure according to claim 11 or 12. 14. A vehicle, characterized in that it has a gearbox according to item 13. 15. The method of supporting the shaft, characterized in that they provide a hollow shaft, pass the rod through the hole in the shaft, provide support for the shaft with bearings, each of which contains a first axial force-absorbing rolling bearing with a ring that rotates with the shaft, a fixed ring and rolling elements between they are installed on the rod at the first end of the shaft the first supporting element containing an axial inner surface with a radially outer part and a radially inner part, and the radially outer h The axial displacement in the axial direction to the shaft relative to the radially inner part provides pressure by the radially outer part of the first supporting element against the stationary ring against the rolling elements of the rolling bearing so that the axial mobility of the stationary ring is limited only on one side by the rolling elements of the bearing and on the other side by the first supporting element, install the shaft bearing in the supporting structure so that the supporting structure limits the axial izhnost first supporting element. 16. The method according to p. 15, characterized in that it is used when using the shaft device according to any one of claims 1 to 10.

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