EP2963256A1 - Drive device for a motor vehicle - Google Patents

Abstract

The invention relates to a drive device for a motor vehicle, in particular for driving an oil pump. The drive device comprises an internal combustion engine for driving the motor vehicle, a lubricant pump for supplying bearings of the internal combustion engine with lubricant and a pump drive device which is drivingly connected and / or connected to the lubricant pump and by means of the lubricant pump independently of the internal combustion engine in an engine start phase and / or an engine shutdown phase is driven.

Description

The invention relates to a drive device for a motor vehicle. The invention particularly relates to an arrangement for driving a lubricant pump for supplying bearings of the internal combustion engine with lubricant.

The internal combustion engine of a motor vehicle requires lubrication for the bearings of the internal combustion engine, in particular for highly loaded plain bearings of the crankshaft, the connecting rods and the camshafts. For this purpose, lubricant pumps are used, which are mechanically driven by the internal combustion engine to provide lubricant under pressure for lubrication.

The lubricant is commonly referred to as oil, although today it is often no longer oil. Accordingly, the lubricant pumps required for this purpose are commonly referred to as oil pumps or oil pressure pumps.

To generate an oil pressure for a low-wear lubrication of bearing and shaft, the lubricant pump needs a certain minimum speed. This is not given when starting and running up the engine.

Such unfavorable Betriebsbedigungen for the internal combustion engine occur in frequent start and stop operations of the internal combustion engine in hybrid drives. In particular, in commercial vehicles with hybrid drive is frequently changed in city operation between internal combustion engine and electric motor drive. When switching from electric drive to internal combustion engine operation, the engine bearings are therefore subject to increased wear, because at engine start sufficient oil pressure in the engine mounts is not given.

On a calculated period of operation, this leads to expensive and time-consuming repair work of engine mounts with unscheduled vehicle life.

From the prior art, it is also known to prevent emptying of the engine lubricating oil holes during engine standstill by means of introduced into the oil delivery circuit check valves. This can be achieved at engine start an accelerated oil pressure build-up. Especially with highly loaded engines with high ignition pressures and difficult Hybrid operating conditions can not be avoided with such check valves a high bearing load or reduced life of the bearings.

It is therefore an object of the invention to provide an improved drive device for a motor vehicle or arrangement for driving a lubricant pump, with which disadvantages of conventional techniques can be avoided. The object of the invention is in particular to provide a drive device for a motor vehicle or arrangement for driving a lubricant pump, which ensures an adequate supply of lubricant even in an engine start phase.

These objects are achieved by a drive device for a motor vehicle having the features of the main claim. Advantageous embodiments and applications of the invention are the subject matter of the dependent claims and are explained in more detail in the following description with partial reference to the figures.

The drive device according to the invention for a motor vehicle comprises an internal combustion engine for driving the motor vehicle and a lubricant pump for supplying bearings of the internal combustion engine or generally for supplying the drive unit with lubricant.

According to general aspects of the invention, the drive device further comprises a pump drive device which is drivingly connectable and / or connected to the lubricant pump and by means of which the lubricant pump can be driven independently of the internal combustion engine in an engine start phase and / or an engine shutdown phase.

A particular advantage of the provision of a separate pump drive device is that the lubricant pump can be driven by this independent of the engine speed and thus enables, in particular in an engine start phase and / or engine shutdown phase independent supply of the lubricant pump from the engine.

According to a particularly preferred embodiment, the pump drive means is an electric motor, i. designed as an electric motor electric machine, which allows a structurally simple implementation.

A particularly advantageous possibility of implementation according to the invention provides that the electric motor, which can drive the lubricant pump independently of the internal combustion engine, and a drive shaft of the internal combustion engine via a freewheel drive be connected to the lubricant pump, such that the lubricant pump by the electric motor by the freewheel faster than by the drive shaft of the internal combustion engine is driven without the drive shaft or the internal combustion engine mitzuschleppen. The freewheel thus enables an advantageous drive-selective coupling of the two drive options for the lubricant pump. In this case, the freewheel decouples the internal combustion engine, in particular in the low rotational speed range of the drive shaft driven by the internal combustion engine, from the lubricant pump.

In an advantageous variant of this embodiment, an outer freewheeling part of the freewheel is operatively connected via a coupling device to the drive shaft of the internal combustion engine. Further, according to this embodiment, a pump drive shaft rotatably connected to the lubricant pump and rotatably connected to an inner freewheeling part of the freewheel and the electric motor is drivingly connected or connectable with a connecting shaft which is coaxial with the pump drive shaft and which is rotatably coupled to the inner freewheeling part. This variant allows a structurally compact design.

According to this variant, there is the possibility that the connection via the freewheel is designed so that the outer freewheeling at stationary drive shaft of the engine is stationary and rotates frictionally with starting drive shaft as long as a speed of the drive shaft at a speed of driven by the electric motor connecting shaft lies. Furthermore, the freewheel according to this variant is designed so that when the rotational speed of the drive shaft of the internal combustion engine exceeds the speed of the connecting shaft, the outer freewheeling part is frictionally coupled to the inner freewheeling part and thus to the pump drive shaft. This can be ensured with appropriate design of the speed of the electric motor, that the engine is coupled only to drive the lubricant pump when it has reached a sufficiently high speed to operate the lubricant pump.

A further variant of this embodiment provides that the connecting shaft and the pump drive shaft are arranged on opposite sides of the freewheel. Advantageously, the connecting shafts of the electric motor and the pump drive shaft are arranged coaxially to allow a simple drive coupling of the connecting shaft with the pump drive shaft.

A particularly advantageous embodiment provides in this case that the connecting shaft via a toothing with the inner freewheeling part rotatably engaged can be brought. The toothing is here preferably designed as axially effective, rotationally rigid intermeshing teeth with radially extending teeth, which allows a stable, positive, rotationally fixed and easily detachable connection of the two drive shafts and at the same time takes up little space. The toothing can be designed, for example, in the form of a Hirth toothing.

In order to frictionally engage or disengage the connecting shaft with the inner freewheel part, the connecting shaft is advantageously axially displaceable. In this case, according to a further aspect of the invention, a control device can be set up to engage or disengage the connecting shaft of the electric motor in a time- and / or speed-controlled manner with the inner freewheeling part.

The invention is not limited to a specific structure with regard to the structural design of the freewheel. The freewheel can be designed for example as a pinch roller freewheel. Further, the inner freewheeling part may comprise a freewheel shaft stub which is arranged coaxially with the connecting shaft and the pump drive shaft and which on one of the lubricant pump side facing rotatably connected to the pump drive shaft and on a side facing away from the lubricant pump rotatably connected to the connecting shaft.

The aforementioned outer freewheeling part can be designed, for example, as a ring gear. Further, the coupling device, by means of which the outer freewheeling part is operatively connected to the drive shaft of the internal combustion engine, be designed as a belt drive, toothing or chain drive.

According to a further aspect, the pump drive device or the aforementioned electric motor may be a starter or a starter generator for starting the internal combustion engine. This offers the advantage that the starter motor or the starter generator in addition to the drive for the internal combustion engine can also be used to drive the lubricant pump, so that no additional electric motor is needed. Preferably, the starter or the starter generator is connected by means of a clutch separable with the internal combustion engine.

A further variant of the implementation according to the invention provides that, instead of a freewheel, the internal combustion engine is drivably connectable to the lubricant pump via a first drive shaft and a controllable clutch. According to this variant, the electric motor is drivingly connected to the lubricant pump via a second drive shaft and a second controllable clutch, wherein the drive device is designed to actuate the first clutch and the second clutch in an engine start phase and / or an engine shutdown phase such that the lubricant pump only is driven by the electric motor. In other words, the internal combustion engine in the start phase and / or the engine shutdown phase can be decoupled from the lubricant pump via the first clutch and only be reconnected when a predetermined minimum speed is reached. After coupling of the internal combustion engine, the electric motor can be decoupled via the second clutch.

For this purpose, it is advantageous to provide a first rotational speed sensor for monitoring a rotational speed of the first drive shaft and a second rotational speed sensor for monitoring the rotational speed of the second drive shaft in order to use the determined rotational speed values of the first drive shaft and the second drive shaft, the coupling and decoupling of the internal combustion engine or To be able to control the electric motor.

According to a further embodiment, the lubricant pump can also be driven exclusively by the electric motor. In this case, the drive of the lubricant pump thus takes place not only in the engine start phase and / or an engine shutdown phase by the electric motor, but during the entire operating time. As a result, an additional improvement in efficiency can be achieved because the purely electrically driven oil pump can be designed so that it provides only the oil pressure that is needed.

According to this variant, it is also advantageous to provide means for current monitoring of the electric motor and means for flow measurement for the lubricant pump in order to be able to optimally control the electric motor. Equally, the reliability of the electric motor and the oil pump is ensured by the sensors and in the event of a fault enables a reliable shutdown strategy of the internal combustion engine.

Furthermore, the drive device for a motor vehicle can be designed as a drive device for a hybrid motor vehicle, wherein in addition to the internal combustion engine for driving the Motor vehicle further comprises an electric motor for driving the vehicle, which is powered by a traction energy storage, is provided.

The invention further relates to a motor vehicle, preferably utility vehicle, with a drive device as disclosed herein.

Figur 1A

eine schematische Querschnittsseitenansicht einer Anordnung zum Antrieb einer Schmiermittelpumpe;

Figur 1B

eine schematische Draufsicht der Anordnung aus Figur 1 A;

Figur 2

eine schematische Draufsicht einer Anordnung zum Antrieb einer Schmiermittelpumpe gemäß einer weiteren Ausführungsform; und

Figur 3

eine schematische Draufsicht einer Anordnung zum Antrieb einer Schmiermittelpumpe gemäß einer weiteren Ausführungsform.

Further details and advantages of the invention will be described below with reference to the accompanying drawings. Show it:

Figure 1A

a schematic cross-sectional side view of an arrangement for driving a lubricant pump;

FIG. 1B

a schematic plan view of the arrangement FIG. 1 A;

FIG. 2

a schematic plan view of an arrangement for driving a lubricant pump according to another embodiment; and

FIG. 3

a schematic plan view of an arrangement for driving a lubricant pump according to another embodiment.

Identical or functionally equivalent elements are denoted by the same reference numerals in all figures.

The cross-sectional view in Figure 1A shows a freewheel 10, which is designed as a pinch roller freewheel. An outer ring gear 11 of the freewheel 10 is mechanically connected via a toothed belt 7 to a shaft 6 driven by an internal combustion engine (not shown). An inner freewheel part 12, also called a star, comprises an inner stub shaft 4 of the freewheel 10, which is arranged coaxially to a pump drive shaft 4, which drives an oil pump, and is rotatably connected thereto, for. B. by means of a screw. The inner stub shaft 4 is on the side facing away from the lubricant pump 3 rotatably connected to a connecting shaft, which is in operative connection with the electric motor 2 (see also FIG. 1B ). The inner arrow indicates the direction of rotation of the driven inner stub shaft 4 of the freewheel 10.

Figure 1A shows also the cylindrical pinch rollers 13 and the springs 14 of the inner freewheeling part 12. Here press springs 14, the pinch rollers 13 easily between the rotating together with the pinch rollers 13 inner part 12 and the outer ring gear 11, so that the pinch rollers depending on their rotation in their Wed recording rooms. Dependent on From the rotational direction or a difference in rotational speed between the rotational speed of the inner freewheel member 12 and the outer ring gear 11, a clamping between the inner freewheel member 12 and the outer ring gear is canceled or produced. The pinch roller freewheel 10 used for this purpose is known per se from the prior art and need not be described in detail here.

At this point, it should only be noted that the freewheel 10 is designed so that the outer freewheeling 11 is stationary with stationary drive shaft 6 of the engine and rotates frictionally at startup of the drive shaft 6 as long as the speed of the drive shaft 6 below the speed of the electric motor driven stub shaft 4 4 lies. When the rotational speed of the stub shaft 4 driven by the electric motor is exceeded, the outer ring gear 11 of the freewheel 10 is frictionally coupled to the inner freewheeling part 12 and in particular the stub shaft 4, which in turn transmits the torque to the pump drive shaft 4a.

Thus, if the rotational speed of the shaft 6 driven by the internal combustion engine exceeds the rotational speed of the electric motor 2, the drive shaft 6 drives the oil pump 3 frictionally via the freewheel 10 and the electric motor 2 can be disconnected and switched off via a clutch mechanism.

FIG. 1B shows the mentioned oil pressure pump 3 with the corresponding connection lines 8 for the oil delivered. The oil pump 3 is driven by the oil pump drive shaft 4 a, which is drivingly coupled to the oil pump 3 via a toothing. The oil pump drive shaft 4a is rotatably coupled to the inner freewheel part 12 and the stub shaft 4 of the freewheel 10, as already explained above. The driven by the electric motor 2 connecting shaft 5 is axially displaceable, which is represented by the arrow marked A in order to be brought into engagement or out of engagement with the stub shaft 4 can. The engagement between the stub shaft 4 and the connecting shaft 5 via a toothed region 7, z. B. via a Hirth toothing, over which the two shafts 4, 5 rotatably engaged with each other can be engaged.

Preferably, such a drive device 1 is used in a hybrid vehicle. In this case, a control device is set up in a known manner to switch to a combustion engine drive of the vehicle when falling below a threshold value for the state of charge of the transaction memory of an electric drive. According to this variant, the control device is also set up when this threshold value is undershot for the state of charge of the transaction memory, which signals an imminent start of the engine to turn on the electric motor 2 and to move the connecting shaft 5 axially and bring into engagement with the stub shaft 4 and thus rotatably coupled to the pump drive shaft 4a, so that the electric motor 2 with the pump 3 is drivingly connected. As a result, sufficient pressure in the bearings of the internal combustion engine can be ensured during the subsequent starting phase of the internal combustion engine.

After the driven by the engine drive shaft has reached a minimum speed, which allows a sufficient supply of the oil pump 3, the electric motor 2 can be decoupled by disengaging the connecting shaft 5 from the freewheel 10 or by decoupling from the pump drive shaft 4a of the oil pump and the electric motor. 2 be switched off subsequently. It is also possible to additionally switch on the electric motor 2 in the phase-out phase of the internal combustion engine in order to maintain the oil pressure up to the crankshaft standstill with nominal pressure.

FIG. 2 shows a further embodiment 20 of the invention, according to which the lubricant pump 3 is driven exclusively by an electric motor 2. For this purpose, the electric motor 2 drives the pump drive shaft 5 directly. A driven by the engine drive shaft is not drivingly connected to the oil pump 3. For current monitoring, a current sensor is further provided on the electric motor 2. Further, a sensor 17 for flow measurement in the output-side oil passage 8 of the oil pump 3 is provided. A control device (not shown) for controlling the electric motor 2 can control the operation of the electric motor on the basis of the determined flow values and current values.

FIG. 3 shows a further drive device 30 for driving an oil pump 3. Here, the electric motor 2 and an internal combustion engine 9 are each independently via driven by them drive shafts 5, 6 drivably coupled to the oil pump 3. Both the shaft 5 driven by the electric motor 2 and the shaft 6 driven by the engine 9 are axially displaceable in order to be able to be engaged and disengaged from the oil pump 3. On the drive shafts 5, 6 each speed sensors 15 are arranged to monitor their speed. A control unit (not shown again) is set up to bring the drive shafts 5 and 6 into and out of engagement with the oil pump 3 as a function of the determined rotational speed values of the rotational speed sensors 15. In particular, the drive shaft 5 is brought into engagement with the oil pump 3 during an engine start phase and / or engine stop phase to drive it. After reaching a minimum speed the drive shaft 6 after starting the engine is then brought into engagement with the oil feed pump 3 and the drive shaft 5 is decoupled from the oil pump 3 again, so that after the starting process of the engine 9 takes over the further drive of the oil feed pump 3.

Although the invention has been described with reference to particular embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents may be substituted for without departing from the scope of the invention. In addition, many modifications can be made without leaving the associated area. Accordingly, the invention should not be limited to the disclosed embodiments, but the invention is intended to embrace all embodiments which fall within the scope of the appended claims.

LIST OF REFERENCE NUMBERS

1

driving means

2

electric motor

3

oil pump

4

Stub shaft of the inner freewheel part

4a

Pump drive shaft

5

connecting shaft

6

driven by the internal combustion engine drive shaft

7

toothed belt

8th

oil line

9

internal combustion engine

10

freewheel

11

Outer ring gear

12

Inner freewheel part

13

pinch roller

14

feather

15

Speed sensor

16

current sensor

17

Flow Sensor

20, 30

driving means

Claims (15)

Drive device (1; 20; 30) for a motor vehicle, comprising
an internal combustion engine (9) for driving the motor vehicle,
a lubricant pump (3) for supplying bearings of the internal combustion engine with lubricant; and
a pump drive device which is drivingly connectable and / or connected to the lubricant pump (3) and by means of which the lubricant pump (3) is drivable independently of the internal combustion engine (9) in an engine start phase and / or engine shutdown phase. Drive device (1; 20; 30) according to claim 1, characterized in that the pump drive device is an electric motor (2). Drive device (1) according to claim 2, characterized in that the electric motor (2) and a drive shaft (6) of the internal combustion engine via a freewheel (10) drivingly connected to the lubricant pump (3) are connectable, such that the lubricant pump (3) of the electric motor (2) by the freewheel (10) faster than by the drive shaft (6) of the internal combustion engine (9) can be driven without mitzuschleppen this. Drive device (1) according to claim 3, characterized in that (A) that an outer freewheeling part (11) of the freewheel (10) via a coupling device (7) with the drive shaft (6) of the internal combustion engine is operatively connected; and (B) that a pump drive shaft (4a) rotatably connected to the lubricant pump (3) and non-rotatably connected to an inner freewheeling part (12) of the freewheel (10); and (C) that the electric motor (2) is drivingly connected or connectable with a connecting shaft (5), which is coaxial with the pump drive shaft (4a), and which is non-rotatably coupled to the inner freewheeling part (12). Drive device (1) according to claim 4, characterized in that the connection via the freewheel (10) is designed so that the outer freewheeling part (11) at stationary drive shaft (6) of the internal combustion engine is stationary and at starting drive shaft (6) so travels long powerless as long as a speed of the drive shaft (6) is below a speed of the electric motor (2) driven connecting shaft (5), and that when exceeding the speed of the connecting shaft (5) the outer freewheeling part (11) is frictionally coupled to the inner freewheeling part (12) and thus to the pump drive shaft (4a). Drive device (1) according to claim 4 or 5, characterized in that the connecting shaft (5) and the pump drive shaft (4a) on opposite sides of the freewheel (10) are arranged. Drive device (1) according to claim 6, characterized (A) that the connecting shaft (5) via a toothing (7) with the inner freewheeling part (12) rotatably engageable engaged; and (B) that the connecting shaft (5) is axially displaceable to bring the connecting shaft (5) into engagement and out of engagement with the inner freewheeling part (12). Drive device (1) according to one of claims 6 or 7, characterized in that the inner freewheel part comprises a freewheel shaft stub (4), which is arranged coaxially to the connecting shaft (5) and the pump drive shaft (4a) and on one of the lubricant pump (3 ) facing side rotatably connected to the pump drive shaft (4a) and on one of the lubricant pump (3) facing away from rotation with the connecting shaft is connectable. Drive device (1) according to one of Claims 4 to 8, characterized (A) that the outer freewheeling part (11) is designed as a ring gear; and or (B) that the coupling device (7) is designed as a belt drive, toothing or chain drive. Drive device (1) according to one of the preceding claims, characterized in that the pump drive device is a starter or a starter generator for starting the internal combustion engine. Drive device (30) according to claim 2, characterized in that (A) that the internal combustion engine (9) via a first drive shaft (6) and a controllable first clutch drivingly connected to the lubricant pump (3) is connectable; (B) that the electric motor (2) via a second drive shaft (5) and a controllable second clutch is drivingly connected to the lubricant pump (3), wherein the drive means (30) is executed, in an engine start phase and / or an engine shut-down phase to operate the first clutch and the second clutch so that the lubricant pump (3) is driven only by the electric motor (2). Drive device (1) according to claim 11, characterized by a first rotational speed sensor (15) for monitoring a rotational speed of the first drive shaft (6) and a second rotational speed sensor (15) for monitoring a rotational speed of the second drive shaft (5). Drive device (20) according to claim 2, characterized in that the lubricant pump (3) exclusively by the electric motor (2) is driven. Drive device (30) according to claim 13, characterized by means for current monitoring (16) of the electric motor (2) and means for flow measurement (17) for the lubricant pump. Motor vehicle, preferably utility vehicle, with a drive device according to one of claims 1 to 14.

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