DE102021202522A1 - Device for cooling and lubricating a transmission for a vehicle - Google Patents

Abstract

Device for cooling and lubricating a transmission (1) by means of a viscous medium (40) for a vehicle (5) with a transmission housing (10) and at least one, in the transmission housing (10) about an axis of rotation (A) and with a direction of rotation ( DR+) rotatable conveying element (12), wherein the axis of rotation (A) of the conveying element (12) is spaced from a housing base (11) of the gear housing (10) by a height (ha) and a first collecting element (30 ) for the viscous medium (40), the first collection element (30) providing an inlet area (16), the inlet area (16) providing a first threshold (31), the conveying element (12) pumping the viscous medium (40) in In the direction of the inlet area (16), the viscous medium (40) only reaches the first collecting element (30) through the inlet area (16) when the viscous medium (40) has overcome the first threshold (31), the first threshold (31) from the housing base (11) a Er extension (ds), wherein the extension (ds) of the first threshold (31) is at least 30% of the height (ha) of the axis of rotation (A) to the housing base (11).

Description

The present invention relates to a device for cooling and lubricating a transmission for a vehicle by means of a viscous medium comprising a transmission housing and at least one conveying element which can be rotated about an axis of rotation A in the transmission housing and a collecting element, the collecting element collecting the viscous medium from the transmission housing in order to using a pump to transport the viscous medium back into the gear housing for lubrication and cooling.

Devices for cooling and lubricating transmissions for vehicles are known. In an advantageous embodiment, the gears are designed with an oil sump, whereby the gear oil located therein is used both as a lubricant and as a coolant for the gear.
Devices for cooling and lubricating transmissions for vehicles in dry sump design are also known. Here, the oil level in the transmission housing is kept as low as possible by the suction stages using a pump system that is characterized by suction stages and pressure stages. The oil sucked out of the gearbox housing is usually pumped into a reservoir where it can defoam. From this reservoir, the oil is fed back into the transmission housing or onto the gears located in the transmission housing by means of the pressure stage of the pump for cooling and lubrication. Relatively large amounts of lubricating and cooling agent are also required in this embodiment in order to ensure the supply of lubricating oil or cooling oil.
With the DE 10 2017 203 527 A1 a dry sump lubrication is disclosed, in which the oil is conveyed from the transmission by means of a driven gear into a collection container and thus no suction pump is necessary to pump the oil out of the transmission housing.

It is the object of the present invention to provide a device for cooling and lubricating a transmission for a vehicle, which works efficiently in all driving states of the vehicle and makes do with the smallest possible amounts of coolant and lubricant.

According to the invention, this object is achieved by a device for cooling and lubricating a transmission using a viscous medium for a vehicle, with a transmission housing and at least one conveying element which can be rotated in the transmission housing about an axis of rotation (A) and with a direction of rotation, the axis of rotation (A ) of the conveying element is spaced apart from a housing bottom of the gear housing by a height and a first collecting element for the viscous medium is adjacent to the conveying element, the first collecting element providing an inlet area, the inlet area providing a first threshold, the conveying element pumping the viscous medium in the direction of the conveys the inlet area, the viscous medium only passing through the inlet area into the first collecting element when the viscous medium has overcome the first threshold, the first threshold providing an extension from the housing base, the extension of the first threshold being at least 30% of the height the axis of rotation (A) to the bottom of the case.
This ensures that sufficient viscous medium such as oil remains in the gearbox housing for lubricating and cooling the gearbox, but also to reduce churning losses caused by rotating gearbox components immersing in oil on the bottom of the housing. These churning losses reduce the efficiency of the transmission and cause the oil to foam, which should be avoided.
In this case, the conveying element can be, for example, a driven gear wheel which is driven by an electric motor. Since the electric motors rotate very quickly, a large translation is necessary. Therefore, the output gear is usually the largest gear in the gearbox and therefore advantageous to use it as a conveying element for the oil, since it is usually provided very close to the bottom of the housing due to its large diameter. When the output gear rotates, the oil that collects on the bottom of the housing and into which the output gear dips is carried along in the direction of rotation of the output gear. Due to the centrifugal force, the oil is released from the output gear and is thrown radially outwards. If the oil is thrown in the area of the said threshold, it flows back to the bottom of the housing. This can ensure that a certain amount of oil remains in the case back. The amount of oil that is thrown radially outward above the threshold can get through the inlet area into the collecting element and collect there. In this case, a pump can be provided at the lower end of the collecting element, which pumps the oil from the collecting element back into the transmission housing.
It has proven to be advantageous that the height of the threshold is at least 30% of the distance between the axis of rotation of the conveying element and the bottom of the housing. A distance between an outer diameter of the conveying element and the bottom of the gearbox housing specifies the amount of oil that is to remain in the gearbox housing.

It can be provided that the first collecting element provides a vertical extension, the first collecting element a Provides a pump for the viscous medium, the pump being provided at a lower end of the vertical extension, the pump returning the viscous medium from the first collecting element to the gear housing for cooling and lubrication.

It can also be advantageous if the axis of rotation (A) of the conveying element is arranged essentially transversely to a direction of travel when the vehicle is traveling straight ahead. Provision can also be made for the collecting element to be located in front of or behind the conveying element in the direction of travel.

Provision can also be made for a second collecting element to be provided, with the second collecting element being provided opposite the first collecting element in order to convey the viscous medium out of the transmission housing when the direction of rotation of the conveying element changes. If the transmission is driven, for example, by the electric machine already mentioned, the transmission can be used in both directions of rotation. In order to ensure that the transmission is supplied with oil in both directions of rotation of the conveying element, two collecting elements are advantageous, as stated, since the return of oil to the collecting elements and thus the oil supply to the transmission can be ensured in both directions of rotation.

The second collecting element can provide a second sill, the second sill providing an extension from the housing floor, the extension of the second sill also being at least 30% of the height of the axis of rotation (A) to the housing floor. It should be pointed out here that the second collecting element is provided as a mirror image of the first collecting element in order to ensure the same advantageous oil supply for both directions of rotation.

In order to use only one pump when using a second collecting element, provision can be made for the second collecting element to be connected to the first collecting element by means of a connecting line. As a result, the oil from the second collecting element reaches the pump in the first collecting element and can be pumped from there back into the transmission for lubrication and cooling.

As already mentioned above, the viscous medium can be an oil.

The pump used can also be designed as a low-pressure pump, which saves energy and improves the overall efficiency of the transmission compared to using a high-pressure pump.

As already explained above, the conveying element can be a gear wheel.

Provision can also be made for the conveying element to be designed as a paddle wheel or as a paddle ring, with the paddle ring being fastened to an existing gear wheel. The impeller can be provided as a separate wheel in the transmission, which, however, does not provide any toothing on the outside, but is provided with blades in order to improve the conveying of the viscous medium from the bottom of the housing. If, on the other hand, a blade ring is used, the blade ring can be attached to an existing gear wheel in order to convey the viscous medium from the bottom of the housing into or into the collecting elements with the blades located on the outside diameter. By using a vane ring with a corresponding diameter, the amount of viscous medium remaining on the bottom of the housing can also be determined. By using vane rings with different diameters, a modular system can be developed that coordinates the conveying element for different gears in order to be able to provide different amounts of viscous medium on the bottom of the housing as required.

The impeller or the impeller ring can be made of metal or plastic.

As already explained above, the vehicle can be an electric vehicle, with the transmission being driven by an electric motor.

• 1 eine erfindungsgemäße Vorrichtung zur Kühlung und Schmierung eines Getriebes,
• 2 eine weitere erfindungsgemäße Vorrichtung zur Kühlung und Schmierung eines Getriebes.

The present invention is described in detail below with reference to the attached figures. It shows:

• 1 a device according to the invention for cooling and lubricating a transmission,
• 2 another device according to the invention for cooling and lubricating a transmission.

• Das Getriebe 1 sieht im äußeren Bereich ein Getriebegehäuse 10 vor. Innerhalb des Getriebegehäuses 10 sind hier ein Förderelement 12, hier als ein Abtriebszahnrad 13 ausgeführt, welches um eine Drehachse A drehbar ist. Das Abtriebszahnrad 13 wird dabei von einem Elektromotor 7 angetrieben. Da die elektrische Maschine 7 hochdrehend ist, circa 20.000 - 24.000 Umdrehungen pro Minute, muss die Übersetzung sehr groß ausgeführt sein. Die Drehachse A ist dabei quer zu Fahrtrichtung vorgesehen. Weiter ist in dieser Ausführungsvariante vorgesehen, dass eine Drehrichtung des Abtriebszahnrades 13 in Uhrzeigerrichtung DR+ ist. Unterhalb des Abtriebszahnrades 13 befindet sich ein Gehäuseboden 11. Dabei ist das Abtriebszahnrad von dem Gehäuseboden mit einer Höhe ha beabstandet. Am Gehäuseboden 11 sammelt sich ein viskoses Medium 40, wie Öl. Weiter ist in Fahrtrichtung gesehen und vor dem Abtriebszahnrad 13 ein erstes Sammelelement 30 vorgesehen. Dabei ist weiter am ersten Sammelelement 30 und zu dem Abtriebszahnrad 13 gerichtet eine Schwelle 31 vorgesehen. Die Schwelle 31 hat dabei eine vertikale Erstreckung ds zum Gehäuseboden 11. Das erste Sammelelement 30 bildet dabei mit der Schwelle 31 und dem Getriebegehäuse 10 einen sich mit einer vertikalen Höhe hv erstreckenden Sammelbehälter 32. An einem unteren Ende des Sammelbehälters 32 befindet sich eine Pumpe 55, die das viskose Medium 40 von dem Sammelbehälter 32 wieder zur Schmierung und Kühlung in das Getriebe pumpt.

With reference to the 1 a first embodiment of a device according to the invention for cooling and lubricating a transmission for a vehicle 5 is described below. The structure is as follows:

• The transmission 1 has a transmission housing 10 in the outer area. Inside the transmission housing 10 are a conveying element 12 here, designed here as a driven gear 13, which is rotatable about an axis of rotation A. The output gear 13 is here by an elec romotor 7 driven. Since the electrical machine 7 is high-speed, approximately 20,000-24,000 revolutions per minute, the translation must be very large. The axis of rotation A is provided transversely to the direction of travel. It is further provided in this embodiment variant that a direction of rotation of the output gear wheel 13 is in the clockwise direction DR+. Below the output gear 13 is a housing base 11. The output gear is spaced from the housing base by a height ha. A viscous medium 40, such as oil, collects on the bottom 11 of the housing. A first collecting element 30 is also provided in front of the output gear wheel 13 as viewed in the direction of travel. A threshold 31 is also provided on the first collecting element 30 and directed towards the driven gear wheel 13 . The sill 31 has a vertical extension ds to the housing base 11. The first collecting element 30 forms, together with the sill 31 and the transmission housing 10, a collecting container 32 which extends with a vertical height hv. A pump 55 is located at a lower end of the collecting container 32 , which pumps the viscous medium 40 from the collection container 32 back into the transmission for lubrication and cooling.

The function is as follows. The driven gear wheel 13 in the transmission housing 10 rotates in the direction of rotation DR+. A quantity of viscous medium 40. Located on the case bottom 11. The rotating output gear 13 dips into the viscous medium 40 and takes it with it. Due to the centrifugal force, the viscous medium 40 is released again from the output gear 13 and is thrown radially outward. If the sill 31 is still in this area, the viscous medium 40 runs along the sill 31 back to the housing base 11. The amount of viscous medium 40 that is thrown away from the output gear 13 above the sill 31 flows or drips through an inlet area 16 into the collection container 32 and is pumped back into the transmission by means of the pump 55 for lubrication and cooling. By using the threshold 31 described, a quantity of viscous medium 40 can be determined which should remain on the bottom of the housing. This quantity of viscous medium 40 is determined on the one hand by a distance between an outer diameter 21 of the output gear 13 and the housing base 11 and on the other hand by the vertical extension ds of the threshold 31 . For an advantageous amount of viscous medium 40 that should remain on the housing base 11, it has been found that the vertical extension ds of the threshold 31 is at least 30% of the distance ha between the axis of rotation A of the output gear 13 and the housing base 11.

the 2 shows a further device according to the invention for cooling and lubricating a transmission. In this respect, the description of the 1 referenced since the 2 in addition to the 1 a second collection element 30a is provided. In this case, the second collecting element 30a is arranged opposite the first collecting element 30 in relation to the output gear wheel 13 . The additional provision of the second collecting element 30a makes it possible to ensure that sufficiently viscous medium 40 is conveyed from the transmission housing 10 into the second collecting element 30a, even if the direction of rotation DR is reversed - of the conveying element 12, i.e. here the output gear 13, with the pump 55 viscous medium 40 pumps back into the transmission 1 for lubrication and cooling. In order not to have to provide an additional pump, the second collecting element 30a is connected to the first collecting element 30 by means of a connecting line 56 . The second collecting element 30a, like the first collecting element 30, provides a second sill 31a, which is also directed towards the output gear 13 and has a vertical extension d's which, like the first sill 31, is at least 30% of the height hA. This ensures that in both directions of rotation DR+ and DR- of the output gear 13, sufficiently viscous medium 40 is conveyed out of the transmission housing 1 through the output gear.

Reference List

1

transmission

5

vehicle

7

electric motor

10

gear case

11

caseback

12

conveying element

13

gear wheel

16

entry area

21

outer diameter

30

first collection item

30a

second collection item

31

first threshold

31a

second threshold

40

viscous medium

55

pump

56

connection line

A

axis of rotation

DR+

direction of rotation

DR

direction of rotation

f

driving direction

ds

extent

d's

extent

Ha

Height

hv

vertical extension

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102017203527 A1 [0002]

Claims (12)

Device for cooling and lubricating a transmission (1) by means of a viscous medium (40) for a vehicle (5) with a transmission housing (10) and at least one, in the transmission housing (10) about an axis of rotation (A) and with a direction of rotation ( DR+) rotatable conveying element (12), wherein the axis of rotation (A) of the conveying element (12) is spaced from a housing base (11) of the gear housing (10) by a height (ha) and a first collecting element (30 ) for the viscous medium (40), the first collection element (30) providing an inlet area (16), the inlet area (16) providing a first threshold (31), the conveying element (12) pumping the viscous medium (40) in In the direction of the inlet area (16), the viscous medium (40) only passes through the inlet area (16) into the first collecting element (30) when the viscous medium (40) has overcome the first threshold (31), characterized in that , that the first threshold (31) of the G ehäuseboden (11) provides an extent (ds), wherein the extent (ds) of the first threshold (31) is at least 30% of the height (ha) of the axis of rotation (A) to the housing base (11). Device for cooling and lubricating a transmission (1) for a vehicle (5). claim 1 , characterized in that the first collecting element (30) provides a vertical extension (hv), the first collecting element (30) providing a pump (55) for the viscous medium (40), the pump (55) at a lower end of the vertical extent (hv), the pump (55) conveying the viscous medium (40) from the first collecting element (30) back into the transmission housing (10) for cooling and lubrication. Device for cooling and lubricating a transmission (1) for a vehicle (5) according to one of the preceding claims, characterized in that the axis of rotation (A) of the conveying element (12) is arranged essentially transversely to a direction of travel (F) when the vehicle is traveling straight ahead is. Device for cooling and lubricating a gearbox (1) for a vehicle (5) according to any one of the preceding claims, characterized in that a second collector element (30a) is provided, the second collector element (30a) being provided opposite the first collector element (30). is to promote the viscous medium (40) from the transmission housing (10) when there is a change in the direction of rotation (DR-) of the conveying element (12). Device for cooling and lubricating a transmission (1) for a vehicle (5). claim 4 , characterized in that the second collecting element (30a) provides a second sill (31a), the second sill (31a) providing an extension (d's) from the housing base (11), the extent (d's) of the second sill (31a ) is also at least 30% of the height (ha) of the axis of rotation (A) to the housing base (11). Device for cooling and lubricating a transmission (1) for a vehicle (5) according to one of Claims 4 or 5 , characterized in that the second collecting element (30a) is connected to the first collecting element (30) by means of a connecting line (56). Device for cooling and lubricating a transmission (1) for a vehicle according to one of Claims 1 until 6 , characterized in that the viscous medium (40) is an oil. Device for cooling and lubricating a transmission (1) for a vehicle according to one of Claims 1 until 7 , characterized in that the pump (55) is a low-pressure pump. Device for cooling and lubricating a transmission (1) for a vehicle (5) according to one of Claims 1 until 8th , characterized in that the conveying element (12) is a gear wheel (13). Device for cooling and lubricating a transmission (1) for a vehicle (5) according to one of Claims 1 until 8th , characterized in that the conveying element (12) is designed as a paddle wheel or as a paddle ring, the paddle ring being attached to an existing gear wheel. Device for cooling and lubricating a transmission (1) for a vehicle (5). claim 10 , characterized in that the paddle wheel or the paddle ring is made of metal or plastic. Device for cooling and lubricating a transmission (1) for a vehicle (5) according to one of Claims 1 until 11 , characterized in that the vehicle (5) is an electric vehicle, wherein the transmission (1) by an electric motor (7) is driven.

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