Hydraulic dry sump system of a gearbox arrangement of a vehicle having at least one electrically driven axle, and drive device

Abstract

The invention relates to a hydraulic dry sump system of a gearbox of a vehicle having at least one electrically driven axle, wherein the hydraulic dry sump system comprises a sump and a reservoir device which is fluidically connected to the sump and which is designed to store fluid, and wherein the hydraulic dry sump system also comprises a lubrication system for directly lubricating at least one component of the gearbox, the lubrication system comprising: a controllable pump unit which is arranged in such a way that it can draw fluid from the reservoir device; and a cooling device which is connected to the pump unit via a fluid line and to which the pump unit delivers the fluid and which cools the fluid; and at least one nozzle which is operatively connected to the cooling device and each of which is arranged in such a way that it emits the cooled and pressurised fluid as a fluid jet in a targeted manner in the direction of a predefined component of the gearbox.

Description

[0001] Hydraulic dry sump system of a transmission arrangement of a vehicle with at least one electrically driven axle, and drive device

[0002] The present invention relates to a hydraulic dry sump system of a transmission assembly of a vehicle with at least one electrically driven axle, as well as a drive device. The hydraulic dry sump system serves for cooling and / or lubricating thermal consumers.

[0003] In a dry sump design, the fluid level is very low, meaning the gears, especially the differential, receive little to no fluid due to the gears' fluid entrainment. Due to the high loads on the differential, sufficient and continuous lubrication (fluid supply) of the critical components in the differential is very important. If indirect lubrication via gears or other indirect lubrication methods (e.g., stator return) is not possible due to the installation space and / or fluid level, an alternative method for supplying the components with fluid is necessary.

[0004] One object of the invention is to provide a continuous fluid supply to critical components of a transmission assembly with a dry sump concept in a vehicle with at least one electrically driven axle. The invention achieves this object by means of the subject matter of the independent claims. Subclaims specify preferred embodiments.

[0005] A hydraulic dry sump system of a transmission of a vehicle with at least one electrically driven axle is provided, wherein the hydraulic dry sump system has a sump and a reservoir device fluidically connected to the sump, which reservoir device is configured to retain fluid, and wherein the hydraulic dry sump system further has a lubrication system for directly lubricate at least one component of the transmission, comprising a controllable pump unit arranged such that it can suck fluid from the reservoir device, as well as a cooling device connected to the pump unit via a fluid line, to which the pump unit conveys the fluid and which cools the fluid, and at least one nozzle operatively connected to the cooling device, each of which is arranged such that it discharges the cooled and pressurized fluid as a fluid jet at specific points in the direction of a predetermined component of the transmission.

[0006] In one embodiment, it is provided that the component of the transmission to be directly supplied with the cooled, pressurized fluid is at least part of a differential of the transmission.

[0007] In one embodiment, the component of the differential is a differential pin of the differential gear.

[0008] In one embodiment, it is provided that the at least one nozzle has a variably adjustable nozzle diameter.

[0009] Furthermore, a drive device of a vehicle with at least one electrically driven axle is provided, comprising a transmission with a differential, the hydraulic dry sump system, and at least one control unit which is configured to control the pump unit of the hydraulic dry sump system in such a way that it pumps fluid from the storage device via the fluid line in the direction of the cooling device and nozzle at a predetermined power.

[0010] In one embodiment, it is provided that the control unit is further configured to determine a quantity of fluid required by the component of the transmission and to adjust the performance of the pump unit accordingly.

[0011] In one embodiment, the control unit is further configured to determine a quantity of fluid required by the component of the transmission and to adjust the nozzle diameter in order to provide this quantity of fluid to the component of the transmission.

[0012] Furthermore, a drive axle is provided, comprising the drive device. Furthermore, a vehicle is provided, comprising the drive device or at least the electric drive axle.

[0013] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which illustrate details of the invention, and from the claims. The individual features can be implemented individually or in combination in a variant of the invention.

[0014] Preferred embodiments of the invention are explained in more detail below with reference to the attached figures.

[0015] Figure 1 shows a drive device in a vehicle with at least one electrically driven axle according to an embodiment of the present invention.

[0016] Figure 2 shows a highly schematic view of a hydraulic system of the drive device according to Figure 1 .

[0017] Figure 3 shows a dry sump transmission according to the state of the art.

[0018] Figure 4 shows a transmission with dry sump and oiling system according to an embodiment of the present invention.

[0019] In the following descriptions of the figures, the same elements or functions are provided with the same reference symbols.

[0020] Figure 1 shows a drive device 100 on a front axle of a vehicle 105. The drive device 100 is configured to drive a drive wheel 110 of the vehicle 105. For this purpose, an electric machine 115 is provided, which can be operated by means of a power converter 120 from an electrical energy storage device 125. While the power converter 120 can be included in the drive device 100, the energy storage device 125 is usually part of the vehicle 105. A transmission 130 is also provided to convert mechanical energy to the drive wheel 110. Optionally, the transmission 130 is configured to be driven by a further drive machine (not shown), for example a reciprocating piston engine. Furthermore, a differential (not shown in the figure) can be provided to transmit the drive power to both drive wheels 110 of the front axle.An identical drive device 100 can be operatively arranged on the rear axle of the vehicle 105 (not shown here) to drive the drive wheel 110 or, if a differential is provided, both drive wheels 110 of the rear axle. Thus, the vehicle 105 has at least two axles, with a drive device 100 according to the invention being operatively arranged on each axle. Each drive device 100 has a hydraulic system 135 according to the invention. The hydraulic system 135 of the front axle is described in more detail with reference to Figure 2, with the statements below analogously applying and being applicable to the hydraulic system 135 of the rear axle.

[0021] A hydraulic system 135 is configured to supply one or more components of the drive device 100, and optionally one or more other components of the vehicle 105, with fluid to cool or lubricate the components. In the following, it is assumed that an oil is used as the fluid for cooling and lubrication. Therefore, the fluid is to be understood as a coolant or lubricant.

[0022] The hydraulic system 135 is a dry sump system in the present case and, according to Figure 2, comprises a pump unit 400 with at least a first pump 200 for suction from a sump 220 and a second pump 205 for suction from a storage device 235, wherein the pumps 200, 205 are arranged on a common shaft 210 that can be driven in rotation by a drive unit 215 in the form of an electric motor in order to convey a volume flow of fluid with each pump 200, 205. The system 135 further comprises a sump 220, which is fluidically connected to an inlet side of the at least one first pump 200 via two suction lines 225, 230. The at least one first pump 200 conveys fluid in the form of coolant or lubricant from the sump 220 into a storage device 235, which is designed to hold fluid for the second pump 205, which supplies the fluid, preferably oil, for cooling or lubricating.Promotes lubrication of thermal consumers or other components not shown in the figure.

[0023] The drive device 100 comprises a housing section for accommodating the electric machine 115 with an intake point configured to be fluidically connected to the first intake line 225 of the at least one first pump 200. The drive device 100 further comprises a housing section for accommodating the transmission 130 with a second intake point configured to be fluidically connected to the second intake line 230 of the at least one first pump 200. The housing sections form the housing of the drive device 100.

[0024] The electric machine 115 of the drive device 100 comprises a stator, a rotor, and winding heads with winding head cooling systems located axially on both sides of the stator. The winding heads with the winding head cooling systems are provided at the axial ends of the stator.

[0025] The drive device 100 is preferably installed in a front-transverse design or in a rear-transverse design, so that the axes of rotation of the electric machine 115 and of the transmission 130 are arranged transversely to the vehicle longitudinal direction or axially parallel and optionally laterally offset to the output shafts of the drive device 100 driving the drive wheels 110 of the respective axle.

[0026] As already mentioned at the beginning, it is typical for dry sump systems that the fluid level is very low, as schematically indicated in Figure 3. Thus, the gears 300 (differential gear), 305 (intermediate shaft gear), 310 (input shaft gear), but especially the differential (and here in particular the differential pin 301 of the differential gear 300) as a critical component, receive little to no oil quantity due to oil entrainment of the gears. Therefore, a concept is needed to supply components of the transmission 130 with fluid reliably, i.e. in particular continuously. A concept is described below with reference to Figure 4 in order to provide a corresponding supply to at least one component of the transmission 130 for a vehicle with at least one electrically driven axle, as shown and described in Figure 1.

[0027] The dry sump system, as described in Figure 2, has a sump 220 and a reservoir 235 for receiving and providing fluid for cooling and / or lubricating components of the transmission 130, as is known from the prior art and schematically illustrated in Figure 3. The sump 220 is fluidly connected to the reservoir 235 in order to transport fluid present in the sump 220 from there into the reservoir 235, from which the fluid for cooling / lubricating components of the transmission 130 is then withdrawn. The fluid level in current dry sump systems is very low, so that the differential in particular cannot be reliably supplied with fluid.Therefore, according to the invention, fluid is pumped out of the storage device 235 by means of the pump 205 of the pump unit 400 and transported via a fluid line 500 to a cooling device 600, in which the fluid is cooled in order to then be discharged onto the component by means of a nozzle 601.

[0028] In the present application, the component to be supplied directly with fluid is a part of the differential, in particular a differential pin 301 of the differential gear 300.

[0029] The pump unit 400 is controllable. It can therefore be controlled via a control unit 700, which specifies the power at which the pump unit 400 should operate. This determines the flow rate of the fluid. The cooling device 600 serves to cool the fluid in the storage device 235, which is in a warm or hot state during operation. The fluid sucked from the storage device 235 by the pump unit 400 and cooled by the cooling device 600 is guided to a nozzle 601 and discharged as a fluid jet 800 by the nozzle 601. The nozzle 601 is either arranged directly on the cooling device 600 or is fluidly connected to it via a fluid line (not shown). Furthermore, the nozzle 601 is positioned (oriented) such that it can discharge the fluid jet 800 selectively in the direction of a component of the transmission 130. The amount of fluid dispensed through the nozzle 601 can be controlled by varying the nozzle diameter.It can be provided that the nozzle diameter is predetermined, i.e. not variable, for each component to be supplied with fluid. In one embodiment, the nozzle diameter of nozzle 601 is variable. This means that nozzle 601 is controllable and can change its nozzle diameter based on the control, e.g. via control unit 700. In this way, the amount of fluid dispensed can be adjusted. In order to provide the best possible cooling (or lubrication), control unit 700 is used to monitor the temperature of the component to be supplied with fluid (e.g. it receives temperature values ​​from temperature sensors) and, based on a comparison of the temperature with a predetermined target temperature, to adjust the amount of fluid that nozzle 601 should dispense.For this purpose, it can control the pump unit 400 and adjust its performance, as well as (additionally or alternatively) adjust the nozzle diameter of the nozzle 601 if it is designed to be variable.

[0030] Due to the pump pressure, a constant pressure is maintained in front of the nozzle 601, whereby the fluid jet 800 has a higher speed than merely redirected fluid from the sump 220. This is helpful because, for example, the differential carrier rotates due to the vehicle speed, thus partially shielding the fluid, so that the fluid jet 800 must ensure lubrication through the opening in the rotating differential carrier. Active (controlled) lubrication with the pressurized fluid enables load-dependent lubrication, not just vehicle speed-dependent lubrication.

[0031] The proposed lubrication system, consisting of pump unit 400, fluid line 500, cooling device 600, and nozzle 601, ensures direct lubrication (fluid supply) of a component of the transmission 130 on a permanent (continuous) basis, particularly in dry sump designs with a low oil quantity in the reduction gear chamber (sump 220). Furthermore, the fluid is cooled, thus no warm / hot fluid from the sump 220 is used, which would result in significantly poorer cooling. Furthermore, the fluid is pressurized, allowing it to be directed more precisely to the component, even if it is partially shielded.

[0032] Only the supply of a single component has been described. However, it is entirely possible to provide multiple nozzles 601 to directly cool / lubricate multiple components, each with a fluid jet 800. For example, several fluid lines can be routed from the cooling device 600 toward the corresponding components, at the end regions of each of which a nozzle 601 is provided, which is then positioned and aligned accordingly to discharge a fluid jet 800 toward the component.

[0033] The control of components in vehicles is known, so the components to which control unit 700 can be operatively connected will not be described in detail here. It is also understood that multiple control units can perform the control task.

[0034] The terms oiling and oiling system always refer to a supply of fluid, which can be oil but does not necessarily have to be.

[0035] The hydraulic system 135 is provided in a drive device 100, which is an electric drive axle, also called an electric axle. By means of the electric machine 115 and the transmission 130 operatively connected thereto, a torque and a rotational speed are provided for driving at least one drive wheel 110 of the vehicle 105. The transmission 130 is operatively connected to a differential, which can distribute the drive power between two output shafts, each of which is connected to a drive wheel 110 of the same axle. Optionally, the transmission 130 can be configured to couple torque from another drive machine, in particular an internal combustion engine.

[0036] In this context, the term “operatively connected” or “operative connection” refers in particular to a non-switchable connection between two components which is intended for the permanent transmission of a rotational speed and / or a torque. The connection can be direct, i.e. immediately, or indirect, for example via a fixed gear ratio. The connection can be made, for example, via a fixed shaft, a gear toothing, in particular a spur gear toothing, and / or a belt or traction device, in particular chains or belts. In the case of an indirect connection, another component can be arranged between the two components. For example, further shafts and / or gears can be operatively arranged between two shafts.

[0037] Reference symbol

[0038] drive device

[0039] vehicle

[0040] Drive wheel electric machine

[0041] Power converter electrical energy storage gearbox hydraulic system first pump second pump

[0042] Wave

[0043] drive unit

[0044] Sump first suction line second suction line storage device

[0045] differential gear

[0046] Differential bolt

[0047] intermediate shaft gear

[0048] Input shaft gear

[0049] Pump unit

[0050] Fluid line

[0051] Cooling device

[0052] nozzle

[0053] Control unit

[0054] Fluid jet

Claims

Patent claims 1. A hydraulic dry sump system (135) of a transmission (130) of a vehicle (105) having at least one electrically driven axle, wherein the hydraulic dry sump system (135) has a sump (220) and a reservoir device (235) fluidically connected to the sump (220) and configured to retain fluid, and wherein the hydraulic dry sump system (135) further has a lubrication system for directly lubricate at least one component (300, 301) of the transmission (130), comprising a controllable pump unit (400) arranged such that it can draw fluid from the reservoir device (235), and a cooling device (600) connected to the pump unit (400) via a fluid line (500), to which cooling device the pump unit (400) conveys the fluid and which cools the fluid, and at least one cooling device (600) connected to the cooling device (600) operatively connected nozzle (601), each arranged in such a waythat it discharges the cooled and pressurized fluid as a fluid jet (800) in a point-like manner in the direction of a predetermined component (300, 301) of the transmission (130).

2. Hydraulic dry sump system (135) according to claim 1, wherein the component of the transmission (130) to be directly supplied with the cooled, pressurized fluid is at least a part of a differential of the transmission (130).

3. Hydraulic dry sump system (135) according to claim 2, wherein the component of the differential is a differential pin (301) of the differential gear (300).

4. Hydraulic dry sump system (135) according to one of the preceding claims, wherein the at least one nozzle (601) has a variably adjustable nozzle diameter.

5. Drive device (100) of a vehicle (105) with at least one electrically driven axle, comprising - a gearbox (130) with a differential, - a hydraulic dry sump system (135) according to one of the preceding claims, - at least one control unit (700) which is designed to control the pump unit (400) of the hydraulic dry sump system (135) in such a way that it pumps fluid from the storage device (235) via the fluid line (500) in the direction of the cooling device (600) and nozzle (601) at a predetermined power.

6. Drive device (100) according to claim 5, wherein the control unit (700) is further configured to determine a quantity of fluid required by the component of the transmission (130) and to adjust the power of the pump unit (400) accordingly.

7. Drive device (100) according to claim 5 or 6, wherein the control unit (700) is further configured to determine an amount of fluid required by the component of the transmission (130) and to adjust the nozzle diameter in order to provide this amount of fluid to the component of the transmission (130).

8. Electric drive axle comprising a drive device (100) according to one of the preceding claims.

9. Vehicle (105) comprising a drive device (100) according to one of claims 1 to 7 or at least one electric drive axle according to claim 8.

Images