TECHNICAL BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention concerns an oil control device for gears according to the pream- ble to claim 1 , a gearbox that contains such an oil control device according to the preamble to claim 14, and a vehicle that contains such a gearbox according to the preamble to claim 15.

In a gearbox, power transfer occurs between gears that are arranged on a number of shafts. The gear setting in the gearbox is determined by the relationship between the number of teeth on the gears on each respective interworking shaft, where two opposing gears arranged on each respective shaft and in engagement with one another form a gear pair. The gears in the gearbox are housed in a gearbox housing, which is partially filled with oil to lubricate and cool the gears during operation. Insufficient lubrication can result in excessive gear friction and wear. Insufficient cooling can result in a critical temperature limit for the oil being exceeded, and in the oil film present in the gear meshing breaking down, leading to gear wear. In addition, rapid degradation of the oil and its continued ability to function satisfactorily occurs as well. Insufficient lubrication and/or cooling thus result in gear damage and a dramatic shortening of the service life of the gearbox. Insufficient cooling can also result in a shortening of the service life of the gears due to the temperature increases in the gears. The gears must be supplied with oil during operation in order to provide thorough lubrication and, most important, sufficient cooling. This is normally ensured by selecting a sufficiently high oil level in the gearbox housing, with the result that affected gears are in oil long enough to be able to be cooled, and so that enough oil will accompany the rotation to the gear mesh.

RECORD COPY TRANSLATION

(Rule 12.4) However, it has been shown that, under certain operating conditions, when the gearbox is mounted in a vehicle, one or more gears will end up above the oil level in the gearbox housing, which leads to insufficient lubrication and cooling of certain gear pairs. The front gear pair in some gearboxes is arranged immediately inside the front side of the gearbox housing. The gearbox in a goods vehicle is normally mounted in the direction of vehicle travel, so that said side is positioned farthest forward in the forward direction of vehicle travel. The gearbox can also be mounted in the vehicle in a somewhat inclined position, whereupon said front side of the gearbox is mounted higher than the corresponding rear side of the gearbox. This exacerbates the problem of providing sufficient lubrication and cooling to the front gear pair. The problem of a low oil level for this gear pair becomes even more noticeable when the vehicle is being driven uphill, whereupon the slope causes the distance between the oil level and the gear in the front gear pair to increase even more. Because a relatively high driving torque is transferred while driving uphill, the result is that the stress on the gears be- comes great, even as the oil supply is at risk of becoming absent.

To solve the problem of absent oil supply, it should be possible to raise the oil level in the gearbox housing by supplying additional oil. However, this entails a problem insofar as the efficiency of the gearbox decreases in the event of an overly high oil level. The problem of shaft seal leakage can also arise.

Patent document SE-C2-520 569 describes a solution to this problem. An oil- conducting element is used to conduct oil to the relevant gear pair from one of the other gears. However, this design entails that certain gears rotate in the gearbox oil bath, which results in drag and splash losses. The design also entails that an uncontrolled volume of oil is supplied to the gear mesh of the gear pair, which can make it difficult for the oil to leave the gear mesh to the same extent as it is being supplied to the gear mesh. The result is that power losses arise in the gear mesh. SUMMARY OF THE INVENTION

Despite known solutions, there is currently a need to further develop a gearbox in order to provide a gearbox with lower power losses than currently known gearboxes, in which gearbox sufficient lubrication and cooling of the gears is achieved.

The object of the present invention is thus to provide a device that ensures the supply of oil to a specific gear or gear pair. A further object of the invention is to provide a device that ensures efficient cooling of a specific gear or gear pair.

Yet another object of the invention is to provide a device that reduces power losses in the gear mesh between a gear pair.

Yet another object of the invention is to provide a device that reduces or eliminates drag and splash losses in connection with gear rotation, and which simultaneously ensures effective lubrication and cooling of a specific gear or gear pair. These objects are achieved by means of an oil control device for gears of the type described above, which device is characterized by the features as specified in claim 1.

Such an oil control device reduces or eliminates drag and splash losses in connection with gear rotation, and simultaneously ensures effective lubrication and cooling of a specific gear or gear pair. The device also reduces power losses in the gear mesh between a gear pair. The result is that when the oil control device is installed in a gearbox in a vehicle, the fuel consumption of the vehicle will decrease at the same time as emissions from the vehicle combustion engine will decrease. These objects are also achieved by means of a gearbox of the type described above, which is characterized by the features as specified in claim 14. These objects are also achieved by means of a vehicle of the type described above, which is characterized by the features as specified in claim 15.

Additional advantages of the invention are identified in the following detailed descrip- tion.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary preferred embodiments of the invention are described below with reference to the accompanying drawings, in which:

Fig. 1 shows a schematic side view of a vehicle 1 with an oil control device for gears and a gearbox that contains such an oil control device according to the present invention,

Fig. 2 shows a perspective view of a gear pair with an oil control device according to a first embodiment of the invention,

Fig. 3 shows a perspective view of a gear pair with an oil control device according to a second embodiment of the invention,

Fig. 4 shows a cross-section of an oil control device according to the second embodiment of the invention, Fig. 5, shows a perspective view of a gear pair with an oil control device according to a third embodiment of the invention, and

Fig. 6 shows a cross-section of a schematically rendered gear pair in a gearbox with an oil control device according to a fifth embodiment of the invention. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE

INVENTION

Fig. 1 shows a schematic side view of a vehicle 100, which vehicle is equipped with an oil control device 102 for gears 104, 106 according to the present invention. The vehicle 100 is also equipped with a gearbox 108, which contains said oil control device 102. The gearbox 108 is connected to a combustion engine 1 10, which drives the vehicle drive wheels 1 12 via the gearbox 108 and a drive shaft 1 14. As an alternative to a combustion engine 110, an electric motor can be used, or a combination thereof. The gearbox 108 can be equipped with an external oil container 1 16 from which oil is supplied to the gears 104, 106 in the gearbox 108. As a result, no oil bath is needed inside the gearbox 108 in which the gears 104, 106 are immersed.

Fig. 2 shows a perspective view of a gear pair 1 18 with an oil control device 102 ac- cording to a first embodiment of the invention. The oil control device 102 comprises a first and second curved element 120, 122, which extend at least partway along the circumference of first and second gears 104, 106, which together constitute a gear pair 1 18 formed in mesh with one another. The extent of the first and second curved elements suitably begins in connection to the mesh of the gear pair 188, after same. Oil supplying means 124 in the form of a tube are arranged on the first and second curved element 120, 122, advantageously at the start of the elements 120, 122 so as, by means of an oil flow, to supply oil to a space 125 between the first curved element 120 and the first gear 104, and to a space 127 between the second curved element 122 and the second gear 106. The oil is thus supplied from the output side of the mesh of the gear pair 1 18. The oil can by supplied by means of the oil supplying means 124 to the spaces 125, 127 directly or indirectly via oil diverting means 138. However, it is possible to equip only the first gear 104 with a first curved element 120, or only the second gear 106 with a second curved element 122. However, to ensure effective lubrication and cooling of the gear pair 188, it is advantageous if the first gear 104 is equipped with a first curved element 120 at the same time as the second gear 106 is also equipped with a second curved element 122. According to the first embodiment, the first and second curved element 120, 122 consists of a respective first and second rail of metal or plas- tic material. It is also possible to use other materials. The first and second curved element 120, 122 can be made of sheet metal, or by casting.

The oil flow is preferably controlled by means of a control unit 126, which varies the supply of the oil flow in dependence upon the rotational speed of the first and second gears 104, 106 and/or the torque transferred by the gear pair 128. The oil supplying means 122 comprise a channel system 128, which is connected to the oil container 1 16 via a pumpl30. The control unit 126 is connected to the pump. Oil that is supplied to the gear pair 1 18 is returned to the oil container 1 16 via a channel (not shown), which is preferably arranged in the lower part of the gearbox 108. It is also possible to control the oil flow by means of the control unit 126, so that the supply of the oil flow varies in dependence upon the temperature of the oil and/or an ambient temperature, e.g. the temperature surrounding the gearbox 108 or the vehicle 100. The control unit 126 is preferably supplied with information concerning the operating states of the vehicle 100, the combustion engine 1 10 and the gear box 108, and supplies oil at a flow rate and volume that ensure effective lubrication and cooling of the gear pair 1 18. After disconnection of the gearbox 108 or the specific gear pair 1 18 in the gearbox 108, the control unit 1 12 can, depending upon the current operating state or on the preceding operating state, instruct the pump 130 to continue to send an oil flow to the gear pair 1 18 for a predetermined length of time in order to cool the gears 104, 106.

According to the first embodiment, the oil supplying means 124 are equipped with an orifice 132, which is arranged on a respective short side 134, 136 of the first and second curved element 120, 122. Oil diverting means 138 are arranged in front of the orifice 132 of the oil supplying means 124, which oil diverting means 138 both conduct oil into respective spaces 125, 137 between the first and second curved element 120, 122 and the first and second gear 104, 106 and protect the mesh of the gear pair 188 from being struck by the oil flow from the oil supplying means 124. If a considerable volume of oil is supplied to the gear mesh of the gear pair 188, the oil can encounter difficulty in leaving the gear mesh to the same extent that is supplied to the gear mesh. The result is that power losses occur in the gear mesh. The oil diverting means 138 thus contribute to increased efficiency in the transfer of torque in the gear pair 1 18. The oil diverting means 138 are preferably made of bent sheet metal or shaped plastic. The oil diverting means 138 can be fabricated by casting. In order for the oil to be conducted into respective spaces 125, 127 between the gears 104, 106 and the curved elements 120, 122 in an efficient manner, the direction of rotation of the gears wheels 104, 106 must be such that the teeth 140 help to introduce the oil into respective spaces 125, 127 between the gears 104, 106 and the curved elements 120, 122 and on through said spaces 125, 127. Fig. 2 shows the direction of rotation of the gears 104, 106 with respective arrows pi and p2. The oil diverting means 138 can be secured on the curved elements 120, 122, or be secured on another component in the gearbox 108.

Fig. 3 shows a perspective view of a gear pair 1 18 with an oil control device 202 ac- cording to a second embodiment of the invention. This embodiment differs from the first embodiment insofar as at least one of the first and second curved elements 220, 22 are equipped with formed flanges 242 extending from at least one side of the section 244 between the element 220, 220. The flanges 242 contribute to keeping the oil in the space 125, 127 between the gears and respective curved elements 220, 222. In the event that the gears 104, 106 are provided with helical teeth 140, as is often the case in vehicle gearboxes 108, it is conceivable that only the one side of the curved element 220, 222 is equipped with a flange 242, as is illustrated in a cross-section view in Fig. 4. The helical teeth 140 force the oil to flow in an axial direction during rotation of the gears 104, 106. By arranging the flange 242 on the side of the curved element 220, 222 to which the oil is being forced to flow by the helical teeth 140, the oil can be kept in the space 125, 127 between respective gears 104, 106 and the curved element 220, 222 for an extended time, thereby ensuring lubrication and cooling of the gears 104, 106.

The intermediate section 244 of the curved elements 220, 222 is disposed at a radial distance from the periphery of the gears 104, 105 and covers at least 25% but advantageously over 50% of the circumference of the gears 104, 105. Viewed in the direction of rotation pi , p2 of the gears 104, 105, the section 244 can ultimately end in a tangen- tial direction in order to facilitate installation in the event that flanges 242 are arranged on both sides of the section 244 and fabricated in one piece, as this enables simple installation of the curved elements 220, 222. If the curved elements 220, 222 only have flanges 242 on one side of the section 244, then installation from the side is simple, and the curved elements 220, 22 can then cover up to ca. 75% of the circumference of the gears 104, 105. However, the curved elements 220, 222 can cover, at most, as large a part of the circumference of the gears 104, 105 that entails that the oil is not prevented from leaving the space 125, 127 in a timely manner and at a distance from the subsequent gear mesh.

There is preferably a degree of play between the section 244 of the curved elements 220, 22 and the gears 104, 105, which play decreases in the direction of rotation pi , p2 so that it is greatest at the inlet of the space 125, 127 and as small as possible at the outlet of the space 125, 127.

The section 244 advantageously covers the entire width of the gears 104, 105 and the flanges 242, which extend on one side or on both sides of the gear 104, 105 in a radial direction in toward the center of the gear 104, 105, so that it covers essentially the entire tooth gap.

When the section 244 is equipped with two flanges 242, one on each side of the gear 104, 105, it is advantageous that neither flange covers the height of the gear 140 in its entirety, but rather leaves an uncovered portion in proximity to the gear root so as to enable a certain outflow of oil from the space 125, 127 in proximity to the gear root in order to achieve a favorable cooling effect from same.

Fig. 5 shows a perspective view of a gear pair 1 18 with an oil control device 302 according to a third embodiment of the invention. According to this embodiment, a connecting channel 346 is arranged between the first and the second curved element 320, 322, which connecting channel 346 conducts oil from the space 125 between the first curved element 320 and the first gear 104 to the space 127 between the second curved element 322 and the second gear. The orifice 132 of the oil supplying means 124 is arranged in an opening 348 in the first curved element 320. Alternatively, the orifice 132 of the oil supplying means 124 can be arranged in an opening (not shown) in the second curved element 322, whereupon oil is conducted from the second space 127 to the first space 125 via the connecting channel 346. When oil is supplied to the space 125 between the first gear 104 and the first curved element 320, the oil will be con- ducted on by the teeth 140 of the first gear 104 by means of the rotation of the first gear 104. The oil is subsequently forced into the connecting channel 346 and conducted on to the space 127 between the second gear 106 and the second curved element 322. The oil is subsequently carried on into the space 127 between the second gear 106 and the second curved element 322 by means of the teeth 140 on the second gear 106 as it rotates. Two connecting channels 346 are preferably arranged side-by-side one another, which both conduct oil from the space 125 between the first curved element 120 and the first gear 104 to the space 127 between the second curved element 322 and the second gear 106. The connecting channels 346 conduct the oil past the gear mesh, on the side of the gear mesh and protect the mesh of the gear pair 1 18 from being sup- plied with far too much oil. As noted above, if a considerable volume of oil is supplied to the gear mesh of the gear pair 1 18, the oil can encounter difficulty in leaving the gear mesh to the same extent as it is being supplied to the gear mesh. The result is that power losses occur in the gear mesh. The connecting channels 346 thus contributed to increased efficiency in the transfer of torque in the gear pair 118. The connecting channels 346 can exhibit a closed profile, but also an open profile such that a lower half of the channel 346 has the shape of an upside-down U, which then interworks with an upper half of the channel having the shape of a right side-up U. The rotation of the first gear 104 causes the oil to be guided by the lower part of the U-shaped channel on to the upper part of the U-shaped channel.

Fig. 6 shows a cross-section view of a gear pair 188 in a gear box 408 with an oil control device 402 according to a fourth embodiment of the invention. According to this embodiment, the first and second curved element 420, 422 comprises a part that is coherent with the gearbox housing 450 that encloses the gear pair 1 18, which part is preferably cast in one piece with the gearbox housing 450. A highly compact design with few components is thus achieved, thereby contributing to a decreased weight of the gear box 408. If the gearbox 408 is installed in a vehicle 100, the low weight of the gearbox 408 contributes to a reduction in the fuel consumption of the vehicle 100. Realizing the curved elements 420, 422 in one piece with the gearbox housing 450 also simplifies the installation of the gearbox 408. The components and features described above can be combined among different described embodiments within the scope of the invention.