Transmission having an oil supply system

Abstract

The invention relates to a transmission (50) having an oil supply system (190) which comprises an oil sump (80) and an oil reservoir (70). Oil can be introduced into the oil reservoir (70) via an inlet (90), and stored oil can be conducted into the oil sump (80) via an outlet (140). The oil reservoir (70) is designed such that a pressure in the oil reservoir (70) corresponds substantially to an ambient pressure (p0) of the transmission (50). The outlet (140) of the oil reservoir (70), in the installed position of the transmission (50), is arranged above the oil sump (80). During operation of the transmission (50), oil is introduced via the inlet (90) into the oil reservoir (70) and is guided, under pressure, from an oil-conducting line (17) of the oil supply system (190) to the inlet (90).

Description

[0001] Gearbox with an oil supply system

[0002] The technology according to the invention relates to a transmission with an oil supply system according to the type defined in more detail in the preamble of claim 1. An oil supply system is understood below to mean any hydraulic system with an operating fluid. The operating fluid can preferably be an oil, but can also be an alternative hydraulic fluid that is not based on hydrocarbons.

[0003] Oil supply systems for transmissions known from practice usually include an oil sump serving as a reservoir or tank for the operating fluid, into which oil from the transmission flows back under the effect of gravity and in which the oil is collected. In addition, oil is sucked from the oil sump by a transmission pump and fed under pressure into a line system of the oil supply system. The condition of the oil circulating in the oil supply system varies depending on the current operating state of a transmission. For example, when a vehicle equipped with the transmission is put into operation after a prolonged period of downtime and at low ambient temperatures, which can be as low as -30 °C, for example, particularly in winter months and depending on the geographical location.In contrast, the operating temperature of the oil can rise to values ​​of 145 °C and above during transmission operating conditions in which high torques are transmitted via the transmission.

[0004] A sufficient oil supply to a gearbox must be ensured within the operating temperature range specified above to ensure long-term functionality. Since both the viscosity and volume of the oil vary greatly within the specified operating temperature range, an oil volume must be maintained in the oil supply system to ensure a sufficient oil supply at both low and high operating temperatures. The temperature-related increase in oil volume with increasing temperature in the oil sump may, under certain circumstances, lead to rotating components of a gearbox submerging in the oil in the oil sump during operation, resulting in splashing losses and undesirable oil foaming.The increased drag torque caused by splashing results in reduced transmission efficiency due to the resulting torque loss, resulting in increased fuel consumption and CO2 emissions. The foamed oil can cause the pump to cavitate, resulting in noticeable noise, material wear and damage, and pressure pulsations, which can lead to functional limitations and even pump failure.

[0005] If, at low operating or oil temperatures, the oil flows back into the oil sump too slowly due to increased viscosity, the oil level drops, which can lead to air being sucked in by the transmission pump. This also results in cavitation, with its well-known disadvantages, as well as an undersupply of hydraulic fluid to the hydraulic consumers. This can lead to a breakdown of the lubrication and cooling of the transmission components, as well as to underfilling or insufficiently rapid filling of the shifting elements, which impairs shifting quality and even interrupts torque transmission.

[0006] For these reasons, an oil reservoir was provided above the oil sump as an expansion tank, also known as a bunker, for regulation purposes, as disclosed, for example, in DE 10 2020 213 955 A1. The oil reservoir is filled through inlets designed as openings in the gearbox housing, through which oil thrown off by rotating gearbox components enters the oil reservoir. The oil reservoir makes it possible to regulate the oil level in the oil sump, so that more oil is retained in the oil reservoir at high temperatures in order to prevent an excessive increase in the oil level due to expansion. The disadvantage of this solution is that filling the oil reservoir depends on the speed of the rotating gearbox components and does not cover all situations for regulating the oil level in the oil sump. Free adjustment of the oil level in the oil sump is not possible.It is a preferred object of the technology according to the invention to ensure a sufficient oil supply to the transmission over the entire operating range of the transmission and at the same time to avoid splashing losses and oil foaming as well as the intake of air during operation of the transmission.

[0007] Ideally, the thermal expansion of the oil should be compensated for, thus keeping the oil level constant over time. To achieve this, it is particularly important to ensure that the oil level can be reliably adjusted over a wide operating range, for example, at different speeds and / or temperatures.

[0008] This object(s) is / are achieved with a transmission having an oil supply system with the features of patent claim 1. Advantageous further developments are the subject of the subclaims and the following description.

[0009] A transmission, in particular an automatic transmission for motor vehicles, is proposed, comprising an oil supply system comprising an oil sump and an oil reservoir. A liquid operating medium, preferably oil, can be introduced into the oil reservoir via an inlet. In addition, oil stored in the oil reservoir can be fed into the oil sump via an outlet, wherein the outlet of the oil reservoir is arranged vertically above the oil sump in the installed position of the transmission. According to the invention, a pressurized, oil-carrying line of the oil supply system is connected to the inlet, so that during operation of the transmission, oil from the pressurized, oil-carrying line can be introduced through the inlet into the oil reservoir. Advantageously, this makes it possible to fill the oil reservoir at any time from the oil supply system of the transmission, so that one is not dependent on the speed of the rotating components that throw off oil, as in the prior art.This allows the oil reservoir to be filled, and thus the oil level in the oil sump to be changed spontaneously and depending on the situation. A pressurized area of ​​a hydraulic system is defined as an area in which, during operation, a pressure greater than the ambient pressure can prevail. The pressurized area is located in the hydraulic system downstream of a pressure source, which could be, for example, a pump or a hydraulic accumulator.

[0010] The oil sump can also be referred to as a tank in which the operating fluid is stored. The oil sump is preferably located at the lowest point of the transmission, so that the fluid from the transmission components or other oil-fillable compartments in the transmission can ultimately drain into the oil sump and collect there.

[0011] An oil reservoir outlet is understood to mean any configuration through which a liquid operating medium, typically oil in the present application, in particular transmission oil, can drain to the transmission sump. Said outlet can preferably be configured as a single opening or as a plurality of openings. This opening can have any cross-sectional shape. A round, in particular a circular, cross-sectional shape can preferably be selected, as this offers the lowest flow resistance, allowing the greatest possible volume flow to drain from the oil reservoir. Ease of manufacture, whether by casting or machining, also plays a role in the selection of the cross-sectional shape. Alternatively, an oval cross-sectional shape can preferably be selected. In principle, the cross-sectional shape can be selected so that the transmission dimensions are affected as little as possible.This is an advantage of an oval cross-sectional shape, as it has a smaller extent in a first direction than in a second direction which runs perpendicular to the first direction. If the outlet comprises a plurality of openings, these can have similar or different cross-sectional shapes. The outlet is preferably formed at the bottom, i.e. at the lowest point of the oil reservoir, and is positioned such that flow can be passed through it essentially vertically from above when the housing or gearbox is in the installed position. A central axis of an outlet cross-section is therefore aligned essentially perpendicular to the earth's surface so that flow can be passed through it under the effect of gravity with the lowest possible flow resistance.

[0012] In this context, flow resistance refers to the pressure difference required for a specific volume flow of a specific operating medium to flow through a constriction at a specific temperature. The flow resistance is calculated based on, among other things, the flow cross-sectional area (also referred to as the flow cross-section), the length of the constriction, the loss coefficient resulting from the geometric design, the volume flow, and the viscosity of the operating medium.

[0013] As far as the shape and number of openings to be flowed through are concerned, this also applies to the inlet, which can have a single opening or a multitude of openings.

[0014] Since the outlet of the oil reservoir is arranged vertically above the oil sump in the installation position of the gearbox, this enables the oil to be discharged from the oil reservoir towards the oil sump by gravity when the outlet is open.

[0015] Preferably, it is possible for the oil reservoir to be designed so that a pressure in the oil reservoir substantially corresponds to an ambient pressure of the transmission. This can be achieved by connecting the space of the oil reservoir to an at least approximately pressure-free space of the transmission or even to the environment itself via a ventilation unit. A pressure-free space in this context is understood to be a space in which at least approximately ambient pressure prevails. If ambient pressure prevails in the oil reservoir, filling is advantageously not made more difficult, as would be the case with overpressure. Overpressure in this context is understood to mean a pressure that is higher than the ambient pressure. As a further advantage, the drainage of the oil through the outlet is not impeded as a result of underpressure. Underpressure in this context is understood to mean a pressure that is lower than the ambient pressure.In a preferred embodiment of the invention, the oil-carrying line is supplied with the operating medium by a gear pump. This allows a pressure and volume flow to be generated in the oil-carrying line within a specific range.

[0016] The gear pump can preferably be designed as a positive displacement pump, such as a vane pump or gear pump. The gear pump can preferably be designed as an internal gear pump with or without a sickle.

[0017] The gear pump can be driven by an internal combustion engine, an electric motor or a superimposed, power-split drive of an internal combustion engine and an electric motor.

[0018] Alternatively or additionally, the pressure source can also be a hydraulic accumulator.

[0019] Preferably, an inflow limiting device is arranged between the oil-carrying line and the inlet, which determines a first volume flow that can be introduced into the oil reservoir or also limits this upwards.

[0020] In a preferred embodiment, the flow resistance of the inlet's inflow limiting device can be selected such that, once the temperature falls below a certain lower limit, the incoming first volume flow does not exceed a certain limit. This prevents overfilling of the oil reservoir at low temperatures.

[0021] The inflow limiting device can be integrated into the inlet or arranged upstream of the inlet in the conveying direction of the operating medium to the oil reservoir.

[0022] In a preferred embodiment of the transmission, the inflow restriction device comprises a throttle and / or an orifice. This advantageously represents a cost-effective and space-saving solution. Alternatively or additionally, a thermostatic valve can be provided between the oil-carrying line and the inlet of the oil reservoir, which only opens the connection between the oil-carrying line and the oil reservoir when the oil temperature exceeds a threshold value. This advantageously allows the flow resistance of the inflow restriction device to vary depending on the temperature, so that at low oil temperatures and the resulting increased viscosity of the operating medium, the fluid is not temporarily stored in the oil reservoir, thus preventing the oil level in the oil sump from falling.In addition, filling the oil reservoir when the oil is cold should be avoided, as depending on the temperature, the oil can only flow back slowly through the outlet into the oil sump, so that the amount of oil removed from the oil sump increases.

[0023] In a further embodiment of the invention, it is alternatively or additionally possible for the inflow limiting device to comprise a control valve. This provides a further variable adjustment option for the first volume flow flowing into the oil reservoir. A configuration as an electrically controllable control valve opens up further possibilities for adjusting the first volume flow.

[0024] In a transmission as described above, it is preferably possible for the flow resistance of the inflow restriction device and the flow resistance of the outlet to be selected and thus coordinated such that a second volume flow flowing out of the outlet at ambient pressure is greater, at least above a specific oil temperature, than a first volume flow flowing into the oil reservoir through the inlet. This prevents oil from accumulating in the oil reservoir even above the specific oil temperature, since more oil always flows out of the oil reservoir than can flow in. This prevents the oil level in the oil sump from falling below a critical value, above which there is a risk that the transmission pump will suck in air.

[0025] Preferably, the specific oil temperature should be below the lowest temperature occurring in practice, so that oil drainage from the oil reservoir is ensured throughout the entire operating range. In a further preferred embodiment of the invention, the outlet comprises a drain control device that determines the volume flow flowing into the oil sump, wherein the flow resistance of the drain control device of the outlet is variable.

[0026] In this context, a preferred embodiment shows that the range of variability of the flow cross-section extends from the maximum flow cross-section to a complete closure of the outlet. At the maximum flow cross-section, as described above, the second, outgoing, volume flow is greater than the first, incoming, volume flow.

[0027] Preferably, it is possible for the sequence control device to comprise an adjustable throttle and / or an orifice.

[0028] This advantageously makes it possible to change the second volume flow and thus adjust the amount of oil stored in the oil reservoir. For example, at low oil temperatures, it is possible to reduce the oil quantity in the oil reservoir by reducing the flow resistance and thus raise the oil level in the oil sump. At high oil temperatures, however, it is possible to withdraw a specific amount of oil from the oil sump by increasing the flow resistance, even to the point of blocking the outlet, and thus lower the oil level, preventing splashing of moving transmission parts in the oil sump.

[0029] Alternatively or additionally, it is possible for the flow control device of the outlet of the oil reservoir to have a blocking element designed as a float, which blocks the outlet of the oil reservoir when the oil level in the oil sump is above the defined threshold value.

[0030] In a further alternative embodiment of the invention, it is possible for the flow control device of the oil reservoir to have a blocking element designed as a wax valve, which blocks the outlet of the oil reservoir when the oil temperature in the oil reservoir is above the threshold value of the oil temperature.

[0031] Preferably, it is possible for the flow resistance of the inflow limiting device of the inlet to be variable.

[0032] The changes in the flow resistance of the flow control device and the inflow limiting device are preferably controlled by an electronic transmission control system. The electronic transmission control system can also record operating-state-dependent transmission variables such as temperatures, oil levels, or speeds.

[0033] In particular, in a preferred embodiment, it is provided that the flow resistance of the inflow limiting device is selected such that a certain value of the volume flow in the transmission lubrication is established at least within a certain temperature range of the oil.

[0034] In a further embodiment of the invention, it is possible for the oil reservoir to be designed with an overflow channel through which oil is directed from the oil reservoir toward the oil sump when the oil level in the oil reservoir exceeds a defined threshold. This also connects the oil reservoir chamber to a pressureless space, so that ambient pressure prevails in the oil reservoir through the overflow channel, providing all the advantages mentioned above.

[0035] According to the invention, a method is provided for operating an above-described oil supply system having a variable inflow limiting device and a flow control device, in which method the flow resistances of the inflow limiting device and the flow control device are varied as a function of specific operating variables. A relevant operating variable is, for example, the oil temperature or the temperature of the operating medium. In this case, it is preferably possible for the flow resistances of the inflow limiting device and the flow control device to be varied as a function of temperature such that, above a first limit temperature, the volume flow entering the oil reservoir through the inlet is greater than the volume flow exiting the outlet.This prevents the oil from accumulating in the oil reservoir and the associated drop in the oil level in the oil sump with all its adverse effects (air being sucked in by the transmission pump).

[0036] In a further embodiment of the method, it is preferably possible for the oil level in the oil reservoir and / or the oil level in the oil sump to be detected, and for the flow resistances of the inflow limiting device and the flow control device to be adjusted upon reaching a specific oil level such that the incoming first volume flow is equal to the outgoing second volume flow, so that the oil level in the oil reservoir and / or the oil level in the oil sump remains constant at a specific value. This allows for the oil level to be adjusted as needed.

[0037] Preferably, the inflow restriction device can be adjusted to set a specific volume flow rate in the transmission lubrication and / or cooling system. This advantageously ensures that the transmission lubrication and / or cooling system are not undersupplied.

[0038] All advantageous effects of the method are achieved by the inventive filling of the oil reservoir from an oil-carrying line of the oil supply system, since this filling can take place spontaneously and independently of speed and temperature.

[0039] In addition, in a further embodiment, the oil reservoir can have at least one further inlet. This further inlet is designed and arranged such that oil thrown off by a component rotating during operation and exposed to oil can pass through the further inlet into the oil reservoir and collect there. An oil filter can be provided upstream of the inflow restriction device, by means of which dirt particles and the like are filtered out of the oil volume flow introduced into the oil reservoir by the inflow restriction device. This provides a simple way of preventing undesired clogging or blockage of the inflow restriction device due to dirt deposits.

[0040] The oil-carrying line can be connected to an outlet of an oil cooler of the oil supply system. This embodiment of the transmission according to the invention has the advantage that the functioning of a lubrication and cooling circuit of the oil supply system is significantly less affected by fluctuations in the supplied oil volume flow compared to shifting elements of a transmission, such as brakes or clutches, which must be engaged or disengaged to achieve a transmission ratio.

[0041] In a structurally simple embodiment, the oil-carrying line can be a bypass line of an oil cooler in the oil supply system, with the inlet of the oil reservoir being connected to the oil-carrying line downstream of a cooler bypass valve. Then, with minimal effort, oil can be introduced into the oil reservoir only once a defined operating temperature has been reached, and thus only once a desired high viscosity has been reached.

[0042] The technology disclosed here will now be explained in more detail with reference to the figures of the drawing, wherein the figures as well as the following description serve only for illustrative purposes and not for the purpose of limiting the invention.

[0043] It shows:

[0044] Fig. 1 is a schematic view of a vehicle drive train of a vehicle with two axles, a drive motor, and a transmission; Fig. 2 is a partial illustration of the hydraulic diagram of an oil supply system of the transmission according to the invention;

[0045] Fig. 3 is a representation of an embodiment of the transmission of the vehicle drive train according to Fig. 1 with an oil supply system according to Fig. 2;

[0046] Fig. 4 is an enlarged view of an area IV identified in more detail in Fig. 3;

[0047] Fig. 5 is an enlarged view of an area V identified in more detail in Fig. 3;

[0048] Fig. 6 is a side view of the transmission according to Fig. 3, wherein a cover element is mounted on a housing of the transmission, which, together with the transmission housing, defines an oil reservoir; and

[0049] Fig. 7 is a side view of another embodiment of the transmission of the vehicle drive train according to Fig. 1.

[0050] Fig. 1 shows a schematic representation of a vehicle drive train 1 with two vehicle axles 2, 3, with a drive unit 4 and with a transmission 50. The drive unit 4 can comprise at least one internal combustion engine, at least one electric machine or also a combination of at least one internal combustion engine and at least one electric machine. The drive unit 4 is connected via the transmission 50 to the vehicle axle 3, which in this case is designed as the vehicle's rear axle. Additionally, there is also the possibility for the vehicle drive train 1 to be designed as an all-wheel drive vehicle drive train, in which case the transmission 50 is then also operatively connected to the vehicle's front axle 2. Additionally, it can also be provided that the vehicle axle 2 is designed as the vehicle's rear axle and the vehicle axle 3 is designed as the vehicle's front axle.

[0051] Fig. 2 shows a schematic representation of part of a hydraulic diagram of the oil supply system 190 of the transmission 50. The hydraulic diagram shows that an oil reservoir 70 of the transmission 50 is connected to an oil-carrying line 17 and can be supplied with oil from this. The oil-carrying line 17 is supplied with oil by a pump 18, which sucks the oil from a pressureless oil sump 80 through an optional suction filter 35. In the oil-carrying line 17, the oil pressure is greater than the ambient pressure pO. The oil-carrying line 17 can in principle be any line of the oil supply system 190 of the transmission 50 in which the oil pressure is greater than the ambient pressure pO and which runs, for example, downstream of the pump 18 in the oil supply system 190. The pump 18 is preferably designed as a positive displacement pump, for example as an internal gear pump with or without a sickle or as an external gear pump, vane cell or piston pump.Alternatively, a hydrodynamic pump (circulating pump, side channel pump, etc.) can be used.

[0052] In the present case, the oil-carrying line 17 is connected to an outlet 20 of an oil cooler 21. Downstream of the oil cooler 21, the oil-carrying line 17 branches off toward a transmission lubrication system 22 and toward the oil reservoir 70. An inflow-limiting device 23 is provided between the oil cooler 21 and the oil reservoir 70, by means of which an oil volume flow toward the oil reservoir 70 can be limited. Upstream of the inflow-limiting device 23, an oil filter 32 is provided, in the area of ​​which dirt particles are filtered out of the oil before the oil flows through the inflow-limiting device 23. The provision of an oil filter at this location is optional, as is the provision of the oil cooler 21.

[0053] In the embodiment of the oil supply system 190 shown in Fig. 2, the inflow restriction device 23 is designed with a throttle 33. In further embodiments, the inflow restriction device 23 can additionally or alternatively also have an orifice or a control valve. The control valve can be designed as a pressure relief valve.

[0054] The oil reservoir 70 preferably has an outlet 140 at its lowest point, through which the oil can flow from the oil reservoir 70 to the oil sump 80. The inflow restriction device 23 with the throttle 33 and the dimensioning of the outlet 140, or rather its flow resistance, are designed such that, in as many operating ranges of the transmission as possible, a larger oil volume flow flows out of the oil reservoir 70 via the outlet 140 than the volume flow flowing into the oil reservoir 70 via the inlet 90. For example, a design is possible such that this is ensured at a certain lowest operating or oil temperature that can normally be expected during operation. This prevents oil from accumulating in the oil reservoir 70 at low oil temperatures, or no or only a small volume of oil is stored in the oil reservoir 70.This prevents an undesirable drop in the oil level in the oil sump 80 below a certain minimum value, which, for example, would cause air to be drawn in by the pump 18. The aforementioned flow resistance of the outlet 140 is determined by its cross-sectional area, the cross-sectional shape, the length of the cross-sectional constriction through the outlet 140, and its loss coefficient.

[0055] Additionally, a flow control device 26 can be integrated into the outlet or arranged between the outlet 140 and the oil sump 80, by means of which the volume flow flowing out of the oil reservoir 70 can be adjusted. In the illustrated embodiment, the flow control device 26 is designed as an adjustable throttle. The adjustment range of the volume flow by the flow control device 26 can extend from the maximum possible volume flow when the outlet 140 is fully open to the complete closure or blocking of the outlet 140. When the outlet 140 is fully open, its lowest flow resistance is set. The flow control device 26 can be designed as an adjustable or fixed throttle or orifice, or as a switchable valve. The adjustment can be temperature-dependent using a thermostat (bimetal, wax element, etc.).) or by an electrical or electromagnetic adjustment, the latter preferably being carried out by an electronic control unit (not shown) in which, for example, the temperature is also recorded.

[0056] A further possibility for controlling the sequence control device 26 is to detect the oil level in the oil reservoir 70 or in the oil sump 80 by means of an oil level sensor (not shown), so that the oil level can be adjusted directly.

[0057] As a further alternative to a flow control device 26, it can be designed as a float, whereby the oil level in the oil reservoir 70 or in the oil sump 80 is taken into account without an additional sensor for the oil level. The outlet 140 can then be opened or closed, for example, via the float as a flow control device, which floats on the oil volume in the oil sump 80 or in the oil reservoir 70.

[0058] If the pressure in the oil reservoir 70 is higher than an ambient pressure pO, filling the oil reservoir 70 is made more difficult, and if this pressure is lower than the ambient pressure pO (negative pressure), emptying the oil reservoir 70 is hindered. In order to avoid undesirable pressure conditions in the oil reservoir 70 with pressures greater or less than the ambient pressure pO, the oil reservoir 70 comprises a ventilation unit 24 through which it is connected to an area of ​​the transmission in which the ambient pressure pO prevails or to the environment itself.

[0059] Optionally, an overflow channel 30 can be provided as the ventilation unit 24, which opens into the unpressurized oil sump 80. If the volume flow flowing out of the oil reservoir 70 through the outlet 140 and the flow control device 26 is too low, the oil level in the oil reservoir 70 rises until the oil can flow through a bore 25 and the overflow channel 30 into the oil sump 80.

[0060] In the oil supply system 190, the return flow of the oil cooler 21 is connected to the oil reservoir 70 via the throttle 33.

[0061] In addition, the throttle 33 is designed such that oil only passes through it into the oil reservoir 70 when the viscosity is below a defined level, i.e., above a certain oil temperature. This prevents oil at a low temperature from entering the oil reservoir 70 and remaining there in the oil reservoir 70 due to excessively high viscosity, which can cause the oil level in the oil sump 80 to drop and thus impair the oil supply to the transmission 50. With the same effect, at low temperatures, and thus high oil viscosities, filling the oil reservoir 70 as described above is made more difficult or even impossible, so that little or no oil is taken from the oil sump 80 and temporarily stored in the oil reservoir 70, so that the oil level in the oil sump 80 does not fall below a critical level at which air could be sucked in by the pump 18.At higher oil temperatures and thus a lower oil viscosity, however, more oil flows through the inflow restriction device 23 into the oil reservoir 70 due to its thinness. As a result, a certain amount of oil is removed from the oil sump 80, so that the oil level in the oil sump 80 drops and splashing losses with the associated harmful oil foaming are reduced or avoided.

[0062] With a complex active control of the inflow limiting device 23, as described above for the flow control device 26, the volume flow flowing into the oil reservoir 70 and thus the oil levels in the oil sump 80 and / or in the oil reservoir 70 can also be adjusted as desired. The inflow limiting device 23 can then either be automatically adjustable depending on the temperature, for example, thermostatically, or, like the flow control device 26, can be controlled from an electronic control unit (not shown) by means of electrically adjustable throttles or orifices.

[0063] Fig. 3 shows a side view of an actual housing 60 of a transmission 50, illustrated in its installed position in a vehicle. An oil reservoir 70 of an oil supply system 190 of the transmission 50 is arranged, as shown, above an oil sump 80 in the vertical direction y of the vehicle. Additionally, Fig. 4 shows an enlarged view of an area IV, identified in more detail in Fig. 3, in which an inlet 90 of the oil reservoir 70 is provided. The inlet 90 comprises a mouth bore 16 extending through a web 12 of the housing 60. Furthermore, Fig. 4 shows a ventilation unit 24 of the transmission 50, via which the oil reservoir 70 or oil bunker is connected to the essentially pressureless interior of the transmission 50. Thus, the inlet 90 and the ventilation unit 24 of the transmission 50 are spatially separated from each other, as also schematically shown in Fig. 2.The ventilation unit 24 of the transmission 50 comprises a bore 25, which is optionally provided in an upper region of the web 12 when the transmission 50 is installed in the vertical direction y of the vehicle and is connected to an overflow channel (not shown) which opens into the interior of the housing 60 of the transmission 50 and ultimately communicates with the oil sump 90. The oil reservoir 70 is delimited in the present case by the housing wall 11 and by a circumferential web 12 which projects outward in the transverse direction x of the vehicle from the outer side of the housing wall 11 of the housing 60. A cover element 15, shown in more detail in Fig. 6, is fastened to an end face 13 of the web 12 facing away from the outer side of the housing wall 11, by means of which cover element 15 the interior of the oil reservoir 70 is sealed off from the environment 28 of the transmission 50.

[0064] Fig. 5 shows an enlarged view of an area V, identified in more detail in Fig. 3, in which an outlet 140 of the oil reservoir 70 is arranged, through which oil can be discharged from the oil reservoir 70. The oil flows out through the outlet 140, driven by gravity, toward the oil sump 80. The outlet 140 can be fully or partially opened or closed via a flow control device (not shown in more detail) in order to store the oil in the oil reservoir 70 in the manner described in more detail below, or to discharge it from the oil reservoir 70 toward the oil sump 80.

[0065] An additional possible design of an inlet 9 is shown in Fig. 7 using a side view of a housing 6 of a transmission 5 in its installed position in a vehicle. The oil reservoir 70 of an oil supply system 19 of the transmission 5 is arranged, as shown, above the oil sump 80 in the vertical direction y of the vehicle. The inlet 9 comprises a plurality of bores 10 which extend through the housing wall 11 of the housing 6 and which establish a connection between an interior of the transmission 5 and the oil reservoir 70. During operation of the transmission 5, oil is thrown off from a so-called transmission tower and partially enters the oil reservoir 70 via the bores 10. The transmission tower comprises rotating components of the transmission 5, which can be designed as clutches, meshing gears, and the like, and which are supplied with oil for cooling and lubrication during operation of the transmission 5.This can be an additional option for filling the oil reservoir 70. In the transmission 5, the inlet 9 simultaneously forms the ventilation unit of the oil reservoir 7, since the oil reservoir 7 is connected via the bores 10 of the inlet 9 to the interior of the transmission 5, in which, as in the oil sump 80, at least approximately the ambient pressure pO prevails. When combining the inlets 9 and 90, the total volume flow introduced into the oil reservoir 70 must be taken into account when designing the outlet 140.

[0066] In other embodiments of the transmission not shown in detail in the drawing, it can also be provided that the filling of the oil reservoir 70 is temperature-controlled via a cooler bypass valve of the oil cooler 21. Such a thermostatic valve can, for example, transition to an open operating state at an oil temperature of 80°C. Furthermore, it is also possible to provide an additional thermal valve as a flow-limiting device, via which a connection between the oil-carrying line 17 and the oil reservoir 70 can be established depending on the temperature.

[0067] Reference symbol

[0068] Vehicle powertrain

[0069] Vehicle axle

[0070] Vehicle axle

[0071] drive unit

[0072] Gearbox

[0073] Housing

[0074] inlet

[0075] drilling

[0076] Housing wall around running web front side

[0077] Cover element

[0078] Outlet bore oil-carrying line pump

[0079] Oil supply system

[0080] Exit

[0081] oil cooler

[0082] Gearbox lubrication

[0083] Inflow restriction device

[0084] Ventilation unit

[0085] drilling

[0086] Sequence control device

[0087] Surrounding overflow channel oil filter

[0088] throttle

[0089] suction filter

[0090] Gearbox

[0091] Housing

[0092] Oil reservoir 80 Oil sump

[0093] 90 entrance

[0094] 140 outlet

[0095] 190 Oil supply system pO Ambient pressure x Vehicle transverse direction y Vehicle vertical direction

Claims

Patent claims 1. Gearbox (5; 50) with an oil supply system (19; 190) comprising an oil sump (8; 80) and an oil reservoir (70), into which oil can be introduced through an inlet (9; 90) and from which stored oil can be directed through an outlet (140) into the oil sump (80), wherein the outlet (140) of the oil reservoir (70) is arranged vertically above the oil sump (80) in the installed position of the gearbox (5; 50), characterized in that a pressurized, oil-carrying line (17) of the oil supply system (190) is connected to the inlet (90), so that during operation of the gearbox (5; 50) oil can be introduced from the pressurized, oil-carrying line (17) through the inlet (90) into the oil reservoir (70).

2. Gearbox with an oil supply system according to claim 1, characterized in that the oil reservoir (70) is arranged such that a pressure in the oil reservoir (70) corresponds substantially to an ambient pressure (pO) of the gearbox (5; 50).

3. Transmission with an oil supply system according to claim 1 or 2, characterized in that the oil-carrying line (17) is supplied with the operating medium by a transmission pump (18).

4. Gearbox with an oil supply system according to claim 1, 2 or 3, characterized in that an inflow limiting device (23) is arranged between the oil-carrying line (17) and the inlet (90), which determines a first volume flow that can be introduced into the oil reservoir (70).

5. Transmission with an oil supply system according to claim 4, characterized in that the flow limiting device (23) comprises a throttle (33) and / or an orifice.

6. Transmission according to one of claims 4 or 5, characterized in that a thermostatic valve is provided between the oil-carrying line (17) and the inlet (90) of the oil reservoir (70), which controls the connection between the oil-carrying The line (17) and the oil reservoir (70) are only released when the oil temperature exceeds a threshold value.

7. Gearbox according to one of claims 4 to 6, characterized in that the inflow limiting device (23) has a control valve.

8. Gearbox with an oil supply system according to one of the preceding claims, characterized in that the flow resistance of the inflow limiting device (23) and the flow resistance of the outlet (140) are selected such that a second volume flow exiting the outlet (140) at ambient pressure (pO) is greater at least above a certain oil temperature than a first volume flow entering the oil reservoir (70) through the inlet (90).

9. Gearbox with an oil supply system according to one of the preceding claims, characterized in that the outlet comprises a drain control device (26) which determines the volume flow flowing into the oil sump, wherein the flow resistance of the drain control device (26) of the outlet (140) is variable.

10. Gearbox with an oil supply system according to claim 9, characterized in that the range of variability of the flow cross-section extends from the maximum flow cross-section to a complete closure of the outlet (14; 140).

11. Transmission with an oil supply system according to claim 9 or 10, characterized in that the flow control device (26) comprises a throttle and / or an orifice.

12. Gearbox with an oil supply system according to one of claims 4 to 1 1 , characterized in that the flow resistance of the inflow limiting device (23) of the inlet (90) is variable.

13. Gearbox with an oil supply system according to one of claims 4 to 12, characterized in that the flow resistance of the inflow limiting device (23) is selected such that at least within a certain temperature range of the oil a certain value of the volume flow in the gearbox lubrication (22) is established.

14. Gearbox according to one of the preceding claims, characterized in that the oil reservoir (70) is connected to a region of the gearbox (5; 50) that is essentially at ambient pressure (pO) or directly to the environment for pressure equalization via a ventilation unit (24).

15. Gearbox according to one of the preceding claims characterized in that the oil reservoir (70) is provided with an overflow channel (30) through which oil is guided from the oil reservoir (70) towards the oil sump (80) when an oil level in the oil reservoir (70) exceeds a defined threshold value.

16. Method for operating an oil supply system according to one of claims 9 to 15, characterized in that the flow resistances of the inflow limiting device (23) and the outflow control device (26) are changed depending on certain operating parameters, in particular the oil temperature.

17. Method according to claim 16 for operating an oil supply system according to claim 11 or 12, characterized in that the flow resistances of the inflow limiting device (23) and the outflow control device (26) are changed as a function of temperature such that above a first limit temperature the volume flow entering the oil reservoir through the inlet is greater than the volume flow exiting through the outlet.

18. Method according to claim 16 for operating an oil supply system according to one of claims 11 or 12, characterized in that the oil level in the oil reservoir (70) and / or the oil level in the oil sump (80) are detected and that, upon reaching a certain oil level, the flow resistances of the inflow limiting device (23) and the outflow control device (26) are adjusted accordingly. that the incoming first volume flow is equal to the outgoing second volume flow, so that the oil level in the oil reservoir (70) and / or the oil level in the oil sump (80) remains constant at a certain value.

19. Method according to one of claims 16 to 18 for operating an oil supply system according to claim 10, characterized in that the flow limiting device is adjusted so that a specific value of the volume flow in the gear lubrication (22) is set.

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