Oil pump, method for the operation thereof, and vehicle

Abstract

The invention relates to an oil pump (1) for a transmission (2) of a vehicle, wherein the oil pump (1) comprises a mechanical drive (3), an electric drive (4) and a pump mechanism (5) which can be driven by the electric drive (4) and / or by the mechanical drive (3), wherein the mechanical drive (3) and the electric drive (4) are each connected to one of two inputs (E1, E2) of a torque balance (6), which is configured to mechanically convert the rotational speeds of the inputs (E1, E2) and to forward the result at an output (A) to the pump mechanism (5), wherein a controller of the oil pump (1) is configured, when the vehicle is at a standstill, to drive the pump mechanism (5) only from the electric drive (4) and, when the vehicle is travelling, to, as required, lower a pump speed of the pump mechanism (5) by backward rotation of the electric drive (4) or increase the pump speed by forward rotation, to overcompensate for the backward-rotating mechanical drive (3) by forward rotation of the electric drive (4) when the vehicle is travelling backwards, and, in normal operation of the vehicle, to operate the pump mechanism (5) only by means of the mechanical drive (3) when a target rotational speed is reached.

Description

[0001] Daimler Truck AG Özvatan November 12, 2025

[0002] Oil pump, method for its operation and vehicle

[0003] The invention relates to an oil pump, in particular for a vehicle transmission, according to the preamble of claim 1, a vehicle according to claim 3, and a method for operating an oil pump according to the preamble of claim 6. The oil pump can be used not only for transmissions, but also for an entire electric drive train and possible auxiliary units and / or for the oil circuit of an electric drive motor of the vehicle.

[0004] A mechanical oil pump, for example in a vehicle, has an approximately linear relationship between delivery volume and pump speed. The pump is relatively inexpensive and achieves very high flow rates and / or delivery capacities. However, the mechanical pump can only supply oil when the speed is reversed using complex switching technology.

[0005] An electric oil pump, on the other hand, is controllable, is not linked to the direction of travel of the vehicle, but is limited in its delivery capacity or otherwise very expensive and is comparatively inefficient, since an electric motor and power electronics bring additional losses.

[0006] In a conventional gearbox with, for example, twelve gears (in commercial vehicles), a mechanical oil pump sits on an input shaft or countershaft and is therefore hardly subject to speed fluctuations.

[0007] Electric drives require fewer gears; therefore, the speed ranges of each shaft are much wider. A mechanical oil pump must thus operate effectively across a wide range of speeds. Low speeds, especially at low vehicle speeds, can lead to insufficient oil flow. This can only be compensated for by significantly oversizing the pump to achieve sufficient flow rates even at low speeds. However, this results in high delivery losses at the target vehicle speed. A purely electric oil pump requires very high delivery rates to achieve the high flow rates required at full load on inclines and is correspondingly expensive. Alternatively, a small mechanical pump and a small electric pump could be installed. However, both pumps would then need to be connected. The actual pump mechanism would also be duplicated in this case, resulting in a significant space requirement.

[0008] DE 102018221 182 A1 describes a pump unit of a motor vehicle transmission that can be driven by an internal combustion engine and an electric motor, comprising an electric motor with a rotor and a stator, a pump with a pump shaft and a summing gearbox for transmitting the torque provided by an internal combustion engine and the electric motor for driving the pump to the pump shaft, wherein the rotor is designed as a hollow cylinder and the pump and the summing gearbox are arranged at least partially in the cavity of the rotor.

[0009] The invention is based on the objective of providing a novel oil pump for a vehicle transmission, a novel vehicle and a novel method for operating an oil pump.

[0010] The problem is solved according to the invention by an oil pump for a transmission of a vehicle with the features of claim 1, a vehicle with the features of claim 3 and by a method for operating an oil pump with the features of claim 6.

[0011] Advantageous embodiments of the invention are the subject of the dependent claims.

[0012] An oil pump for a vehicle transmission is proposed, wherein the oil pump has a mechanical drive, an electric drive, and a pump mechanism that can be driven by the electric drive and / or the mechanical drive, wherein the mechanical drive and the electric drive are each connected to one of two inputs of a torque balance configured to mechanically calculate, for example, add up, the speeds and torques of the inputs and to pass the result to the pump mechanism at an output, wherein a control of the oil pump is configured to drive the pump mechanism only from the electric drive when the vehicle is stationary, and to decrease the pump speed of the pump mechanism as required by reversing the electric drive or increasing the pump speed by turning it forward when the vehicle is in motion.According to the invention, the control of the oil pump is further configured to overcompensate for the reverse-rotating mechanical drive by rotating the electric drive forward when the vehicle is traveling in reverse, and to drive the pump mechanism only by the mechanical drive when a target speed is reached during normal operation of the vehicle.

[0013] The calculation of torques and / or speeds is carried out according to the transmission ratio of the torque balance.

[0014] In the context of the present invention, the term "mechanical drive" refers to a drive that is mechanically coupled to the vehicle's drivetrain. In an electric drivetrain, the mechanical drive is also provided by an electric motor (also referred to as a traction motor). In the context of the present invention, the term "electric drive" refers to a dedicated electric motor whose sole or primary function is to power the oil pump. The torque balance is also mechanically connected to this electric motor.

[0015] The oil pump according to the invention achieves the required volume flow cost-effectively and with minimal installation space.

[0016] Thanks to the solution according to the invention, the actual pump mechanism does not need to be oversized. The advantages of a mechanical and an electric pump are combined. The mechanical side also provides a kind of fail-safe for the electric pump drive. Both are achieved in a minimal package, since all pump components are used for both drive types.

[0017] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing.

[0018] This shows:

[0019] Fig. 1 : a schematic view of an oil pump for a vehicle gearbox.

[0020] Figure 1 is a schematic view of an oil pump 1 for a transmission 2 of a vehicle, for example, a commercial vehicle, a bus, or a passenger car, in particular a vehicle that is at least partially electrically powered. The oil pump 1 has a mechanical drive 3 and an electric drive 4. Furthermore, a pump mechanism 5 is provided (only one is shown), which can be driven by the electric drive 4 and / or the mechanical drive 3. It is provided that at low speed, in reverse, or for preconditioning, the pump mechanism 5 is driven by the electric drive 4, and that at a target speed, for example, when driving on a highway, the pump mechanism 5 is driven by the mechanical drive 3, which is coupled to the transmission 2.Instead of a freewheel where only one drive type is active at any given time, it is intended that both drive types are taken into account, in particular added together, regardless of their speed and / or power.

[0021] Both drives 3, 4 (electrical and mechanical) are balanced, for example added together, by a torque balancer 6 before reaching the actual pump mechanism 5. The housing of the oil pump 1 therefore does not need to rotate. The torque balancer 6, for example a small planetary gear set, mechanically balances two inputs E1, E2 from drives 3, 4, like a differential, and transmits the result to the pump mechanism 5 via an output A.

[0022] By mechanical summation in the torque balance 6 (planetary wheel set), four relevant operating points can be optimally represented.

[0023] In a first operating point, the vehicle is stationary and the pump mechanism 5 is driven only by the electric drive 4 (preconditioning).

[0024] In a second operating point during reverse travel, the electric drive 4 overcompensates for the reverse-rotating mechanical drive 3.

[0025] In a third operating point during normal operation (cruising), no power is required from the electric drive 4 and the pump mechanism 5 is driven only by the mechanical drive 3.

[0026] In a fourth operating point (modulation), the electric drive 4 is used as an additional degree of freedom. By drawing power (rotating backwards), the electric drive 4 can reduce the pump speed of the pump mechanism 5. By adding power (rotating forwards), the electric drive 4 can increase the pump speed and thus the flow rate. The aim is to optimize the pump speed for energy consumption reduction or predictive conditioning. Daimler Truck AG Özvatan 12.11.2025

[0027] Reference symbol list

[0028] 1 oil pump

[0029] 2 gearboxes

[0030] 3 mechanical drive

[0031] 4 electric drive

[0032] 5 Pump mechanics

[0033] 6 Torque scale

[0034] A Exit

[0035] E1, E2 Entrance

Claims

Daimler Truck AG Özvatan November 12, 2025 Patent claims 1. Oil pump (1) for a transmission (2) of a vehicle, wherein the oil pump (1) has a mechanical drive (3), an electric drive (4) and a pump mechanism (5) which can be driven by the electric drive (4) and / or the mechanical drive (3), wherein the mechanical drive (3) and the electric drive (4) are each connected to one of two inputs (E1, E2) of a torque balance (6) which is configured to mechanically calculate the rotational speeds of the inputs (E1, E2) and to transmit the result to the pump mechanism (5) at an output (A), wherein a control of the oil pump (1) is configured to drive the pump mechanism (5) only from the electric drive (4) when the vehicle is stationary, and to decrease the pump speed of the pump mechanism (5) as required by reversing the electric drive (4) or increasing the pump speed by forward rotation when the vehicle is in motion. characterized in that the control of the oil pump (1) is further configured to overcompensate for the reverse-rotating mechanical drive (3) by rotating the electric drive (4) forward when the vehicle is traveling in reverse, and to drive the pump mechanism (5) only by the mechanical drive (3) when a target speed is reached during normal operation of the vehicle.

2. Oil pump (1) according to claim 1, characterized in that the torque balance (6) is designed as a planetary gear set.

3. Vehicle with a transmission (2) and an oil pump (1) according to claim 1 or 2.

4. Vehicle according to claim 3, configured as a commercial vehicle or bus.

5. Vehicle according to claim 3 or 4, designed as a vehicle that is at least partially electrically powered. 6.Method for operating an oil pump (1) for a transmission (2) of a vehicle, wherein the oil pump (1) has a mechanical drive (3), an electric drive (4) and a pump mechanism (5) which can be driven by the electric drive (4) and / or the mechanical drive (3), wherein the mechanical drive (3) and the electric drive (4) are each connected to one of two inputs (E1, E2) of a torque balance (6) which mechanically calculates the rotational speeds of the inputs (E1, E2) and transmits the result to the pump mechanism (5) at an output (A), wherein when the vehicle is stationary the pump mechanism (5) is driven only by the electric drive (4), and when the vehicle is moving at low speed the pump speed of the pump mechanism (5) is reduced as required by reversing the electric drive (4) or increased by turning it forward. characterized in that when the vehicle is traveling in reverse, the reverse-rotating mechanical drive (3) is overcompensated by the forward rotation of the electric drive (4), and in normal operation of the vehicle, when a target speed is reached, the pump mechanism (5) is driven only by the mechanical drive (3).

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