Independent rear suspension for a motor vehicle having an electric drivetrain

Abstract

The invention relates to an independent rear suspension (10) for a motor vehicle with an electric drive train (60). The independent rear suspension (10) comprises a left semi-trailing arm (14) and a right semi-trailing arm (28), each of which can be articulated to the chassis of the motor vehicle at the end on the vehicle body side and fixedly connected to the wheel frame (48, 54) at the end on the wheel frame side, and also comprises a transverse leaf spring (42) for suspending the rear wheels (50, 56). According to the invention, the transverse leaf spring (42) is connected to the end of the semi-trailing arm (14, 28) on the wheel frame side, so that an open installation space (12) for receiving at least a part of the electric drive train (60) is formed between the semi-trailing arm (14, 28) and the transverse leaf spring (42).

Description

Technical Field

[0001] The invention relates to an independent rear suspension for a motor vehicle with an electric drive train, comprising a left semi-trailing arm, a right semi-trailing arm and a transverse leaf spring for suspending the rear wheels. The invention also relates to a motor vehicle with an electric drive train and such an independent rear suspension. Background Art

[0002] In the field of vehicle technology, when it comes to motor vehicles, a variety of different suspensions for the wheels of motor vehicles are known in the prior art. A particular distinction can be made between independent suspensions, which are now mainly used for passenger vehicles, and rigid suspensions, which are mainly used for the rear axles of commercial vehicles. In addition, however, there are also so-called semi-rigid axles, in which the wheels of the axle arranged on both sides or their wheel carriers are connected to two trailing arms, which are pivotably connected to the body at the end on the body side, perpendicular to the chassis.

[0003] A semi-trailing arm axle known in the prior art is a special embodiment of an independent suspension, which is often used as a suspension for the rear axle in motor vehicles. A semi-trailing arm axle in principle comprises a triangular semi-trailing arm which is fixedly connected to the wheel carrier and is movably, for example pivotably, mounted on the vehicle body.

[0004] For example, US 2011 / 0227310 A1 describes a semi-trailing arm axle for a motor vehicle having a semi-trailing arm for each wheel of the axle, the semi-trailing arm being flexible about a vertical axis and being connected to the vehicle body or auxiliary frame via at least one bearing. In this case, each wheel of the axle is connected to a respective flexible semi-trailing arm via at least one wheel bearing, whereby the flexible semi-trailing arm is the only wheel guide element.

[0005] In the described embodiment, at least one transverse leaf spring connected to a semi-trailing arm or wheel carrier is provided, and for each suspension at least one shock absorber is connected to a flexible semi-trailing arm or wheel carrier.

[0006] Also known from the prior art transverse leaf springs are used for suspensions, particularly rear suspensions. In this case, the transverse leaf spring can have one or more functions of a stabilizer, a spring and a wheel-guided transverse control arm.

[0007] Thus, for example, WO 2009 / 094973 A1 describes an axle suspension for a vehicle, in particular a rear axle suspension, having a first trailing arm fixedly connected to a first wheel carrier, which is articulated to the body of the vehicle via a first bearing. Furthermore, the axle suspension comprises a second trailing arm fixedly connected to a second wheel carrier, which is articulated to the body via a second bearing. In this way, the trailing arm pivots relative to the body about a pivot axis. Furthermore, the axle suspension comprises a first wheel rotatably mounted on the first wheel carrier and a second wheel rotatably mounted on the second wheel carrier. In this way, the two trailing arms are connected to each other via a transverse connection, which is rotatably mounted on the trailing arm behind the center of the wheel when viewed from the bearing.

[0008] In the described embodiment, the transverse connection element is designed as a leaf spring and in particular as a leaf spring made of glass fiber reinforced plastic (GFP), which is mounted or supported on the vehicle body between two trailing arms. The transverse leaf spring can have a wheel guide function.

[0009] In addition, WO 2014 / 202301 A1 describes a suspension for a motor vehicle. The suspension comprises two wheel carriers arranged opposite each other in the transverse direction of the vehicle, each of which is connected in an articulated manner to a vehicle body designed for this purpose via at least one wheel guide control arm. In addition, the suspension comprises a transverse leaf spring extending between the two wheel carriers, which is mounted for compression and rebound of the wheel carrier in the region between two ends spaced apart therefrom and is connected to the wheel carrier assigned in each case in the region of their ends. According to the invention, the wheel guide control arms are arranged in a lower control arm plane and the transverse leaf springs are arranged in a control arm plane above the lower control arm plane in the vertical direction of the vehicle. By designing the axle with a wheel guide passing through the transverse leaf spring, the number of components can be reduced and the axle can therefore have an overall advantageous design in terms of its weight and costs.

[0010] In particular, the use of a transverse leaf spring means that no additional control arms are required and in this way sufficient installation space can be created for a solution in which the wheel carrier is connected to a drive unit, which can be designed as a wheel hub motor or an electric motor and / or an internal combustion engine.

[0011] Furthermore, WO 2016 / 096293 A1 describes a rear suspension for a motor vehicle. The rear suspension comprises:

[0012] - a wheel carrier which can be pivoted about a steering axis and is used to receive the wheel in a steerable manner,

[0013] - a wheel control arm which is arranged in the lower control arm plane relative to the vertical axis of the vehicle and can be connected in an articulated manner on the body side to the vehicle body provided therefor and in an articulated manner to the wheel carrier on the wheel side,

[0014] - a wheel-guiding transverse link arranged in the plane of the upper control arm, which can be connected in an articulated manner on the body side to the body provided for it and in an articulated manner on the wheel side to the wheel carrier, and

[0015] - A transverse leaf spring having a two-point bearing on the body side, which is connected at its end facing the wheel carrier in an articulated manner to said wheel carrier behind the wheel center relative to the direction of travel.

[0016] The transverse control arm is arranged in front of the transverse leaf spring in the direction of travel, and the transverse leaf spring is connected in an articulated manner to the wheel carrier below the transverse link in the vertical direction of the vehicle, so that the transverse leaf spring is designed as a toe control link for passive steering of the wheel via the wheel hub. The transverse leaf spring thus combines three important functions of the rear suspension, namely the functions of suspension, stabilizer and toe link, in a single component. The rear suspension is therefore best suited for driven rear axles, in particular with conventional drive technology, or also for electric drives, preferably wheel hub motors.

[0017] In view of the disclosed prior art, the field of rear suspension still offers scope for improvement in relation to electrically driven rear wheels. Summary of the invention

[0018] The problem addressed by the invention is to provide a compact rear suspension for an electrically drivable motor vehicle which allows a high level of driving comfort.

[0019] It should be noted that the features and measures listed individually in the following description may be combined with one another in any technically feasible manner to disclose further embodiments of the present invention. The description together with the accompanying drawings depicts and explains the present invention.

[0020] The independent rear suspension of a motor vehicle with an electric drive system according to the present invention has a left semi-trailing arm and a right semi-trailing arm, each of which can be hinged to the chassis of the motor vehicle at the end on the body side and fixedly connected to the wheel frame at the end on the wheel frame side, and has a transverse leaf spring for suspending the rear wheel.

[0021] In this case, the transverse leaf spring is connected at the end side to the wheel carrier-side end of the semi-trailing arm, so that an open installation space for receiving at least a part of the electric drive train is formed between the semi-trailing arm and the transverse leaf spring.

[0022] A “motor vehicle” in the sense of the present invention is to be understood as meaning in particular a passenger car, a heavy goods vehicle, an articulated lorry or a coach.

[0023] A high level of driving comfort can be achieved by the independent rear suspension according to the invention. At the same time, by suitable embodiments, an installation space which is optimized for receiving at least a part of the electric drive can be provided.

[0024] Since the semi-trailing arm can be fixedly connected to the wheel carrier at its end on the wheel carrier side, as an alternative to the connection of the transverse leaf spring at its end on the wheel carrier side, the transverse leaf spring is also fixedly connected to the wheel carrier at one end.

[0025] The transverse leaf spring is preferably fixed to the chassis of the motor vehicle via a central region. In this case, the transverse leaf spring can be arranged in such a way that, in a state in which the independent rear suspension only statically carries chassis loads, the transverse leaf spring has an upwardly convex shape in the vertical direction. However, the transverse leaf spring can also be constructed in such a way that, in this state, the transverse leaf spring extends substantially in a plane arranged parallel to the road surface.

[0026] In a preferred embodiment, the connection between the transverse leaf spring and the semi-trailing arm is arranged at a distance from the axis of rotation of the rear wheel in the rearward direction. In this way, it can be achieved that the open installation space includes areas close to the wheel axle, which are particularly important when receiving at least part of the electric drive.

[0027] The connection of the transverse leaf spring to the end of the semi-trailing arm on the wheel carrier side is guided through at least one substantially vertically oriented connecting rod or vertical shear pad unit. In this way, the area close to the wheel axle for receiving at least part of the electric drive can also remain free in the vertical direction.

[0028] A "connecting rod" (also called: rocker) within the meaning of the present invention is to be understood as meaning a straight, usually metal rod, at the ends of which fastening elements are mounted in an articulated manner, for example using rubber bearings. The connecting rod can only transmit forces in the longitudinal direction. In this way, the vertical spacing between one end of the semi-trailing arm on the wheel carrier side and the connecting end of the inclined leaf spring is fixed; however, lateral movements are possible to a predetermined extent. Connecting rods are widely available and used in vehicle technology, for example for fastening stabilizers (torsion bar springs). A similar function can be achieved by a vertical shear pad unit, which can consist, for example, of a rubber-elastic material that is stretched under the action of lateral forces.

[0029] If the wheel carrier-side end of the semi-trailing arm is arranged below the rotation axis of the rear wheel and the body-side end of the semi-trailing arm is arranged above the rotation axis, the area close to the wheel axle and also close to the wheel can be used as an open installation space.

[0030] In a preferred embodiment, the body-side end of the semi-trailing arm is designed in a fork-shaped manner and is provided with two separate bushings for articulation to the chassis of the motor vehicle. In this way, by suitable construction, a recess can be provided in the transverse control arm, whereby a weight reduction in the unsprung masses of the motor vehicle can be achieved while maintaining the intended function of the semi-trailing arm.

[0031] The device for connecting the damping element is preferably provided at each end of the semi-trailing arm on the wheel carrier side. By tightly connecting the damping element at each end of the transverse leaf spring, effective damping of the excited vibrations can be achieved. The damping element is preferably designed as a shock absorber.

[0032] In a preferred embodiment, the transverse leaf spring contains a major proportion of composite plastic. In this way, compared with a conventional transverse leaf spring made of steel, the transverse leaf spring can be arranged with a lightweight structure with a particularly large weight reduction.

[0033] The term "predominant proportion" is to be understood within the meaning of the invention to mean in particular a proportion of more than 50% by volume, preferably a proportion of more than 70% by volume and particularly preferably a proportion of more than 90% by volume. In particular, the term is to include the possibility of the transverse leaf spring being made completely of composite material, that is to say 100% by volume.

[0034] The composite material may be realized, for example, as a fiber-reinforced plastic (FRP). In particular, the composite material may contain a carbon fiber-reinforced plastic (CFP), a glass fiber-reinforced plastic (GFP) and / or an aramid fiber-reinforced plastic (AFP).

[0035] In another aspect of the invention, a motor vehicle is proposed, which comprises an electric drivetrain, which comprises an electric motor and two drive shafts. Furthermore, the motor vehicle is equipped with an independent rear suspension according to the invention. In this case, the electric motor is arranged in the open installation space between the semi-trailing arm and the transverse leaf spring, and each of the two drive shafts is operatively connected to one of the rear wheels of the motor vehicle.

[0036] The term "operably connected" within the meaning of the present invention is to be understood as meaning in particular that the operably connected objects are mechanically connected to one another in such a way that a transmission of forces and / or torques and / or torsional moments between the objects is possible. In this case, the transmission can take place both by direct contact and also indirectly via intermediate elements.

[0037] The advantages described in conjunction with the proposed independent rear suspension are fully transferable to such a motor vehicle.

[0038] In a preferred embodiment of the motor vehicle, the electric motor is arranged in a central region of the open installation space and, proceeding from either side of the electric motor, two drive shafts are arranged flush with the axis of rotation of one of the rear wheels.

[0039] In this way, a short and efficient transmission path for the torque of the electric motor to the rear wheels can advantageously be achieved, whereby components can also be saved by suitable embodiments.

[0040] The electric motor is preferably fixed to the chassis of the motor vehicle, whereby the unsprung masses of the motor vehicle can be kept low. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Further advantageous embodiments of the invention are disclosed in the dependent claims and in the drawings described below. In the drawings:

[0042] Figure 1 A schematic diagram of an independent rear suspension of a motor vehicle according to the invention is shown, with an electric drive train in a mounted state in plan view. DETAILED DESCRIPTION

[0043] Figure 1 A schematic diagram of a possible embodiment of an independent rear suspension 10 for a motor vehicle is shown with an electric drivetrain 60 in plan view. Figure 1 A straight-ahead driving direction 68 of a motor vehicle designed as a passenger car is shown from bottom to top, ie parallel to the X direction.

[0044] The independent rear suspension 10 has a left semi-trailing arm 14 and a right semi-trailing arm 28, each of which is made of steel, for example, and has an outer shape that corresponds substantially to the shape of a conical equilateral triangle. The semi-trailing arms 14, 28 can also be made of different materials, among which light metals or composite materials are conceivable, also fiber-reinforced plastics.

[0045] Each of the two semi-trailing arms 14, 28 is articulated at the end on the body side corresponding to the base of the equilateral triangle to an auxiliary bracket of the chassis (not shown) of the motor vehicle or directly to the chassis (not shown). The ends on the body side of the semi-trailing arms 14, 28 are configured in a fork shape and are each provided with two separate bushings 16, 18, 30, 32 for articulation to the chassis or directly to the chassis, so that the left semi-trailing arm 14 is pivotably mounted about a left pivot axis 20 extending obliquely relative to the straight-ahead driving direction 68 and the right semi-trailing arm 28 is pivotably mounted about a right pivot axis 34 extending obliquely relative to the straight-ahead driving direction 68. Between its two bushings 16, 18, 30, 32, each semi-trailing arm 14, 28 is provided with a circular sector-shaped recess 22, 36 for weight reduction.

[0046] The left semi-trailing arm 14 is fixedly connected to the left wheel carrier 48 at the end on the wheel carrier side corresponding to one side of the leg of the equilateral triangle. In a mirrored manner, the right semi-trailing arm 28 is fixedly connected to the right wheel carrier 54 at the end on the wheel carrier side corresponding to the leg of the equilateral triangle. In this way, the left rear wheel 50, the left wheel carrier 48 and the left semi-trailing arm 14 connected to the left wheel carrier 48 are pivotably mounted about the left pivot axis 20 and independently of the right rear wheel 56, which is connected to the right wheel carrier 54 and is pivotably mounted together with the right semi-trailing arm 28 about the right pivot axis 34.

[0047] The left rear wheel 50 and the right rear wheel 56 are connected in a manner known per se to the respective wheel carrier 48 , 54 , such that they are rotatably mounted about a left axis of rotation 52 or a right axis of rotation 58 .

[0048] When the independent rear suspension 10 only statically bears the chassis load, the ends of the semi-trailing arms 14, 28 on the wheel frame side are arranged below the rotation axes 52, 58 of the rear wheels 50, 56 and the ends of the semi-trailing arms 14, 18 on the vehicle body side are arranged above the rotation axes 52, 58.

[0049] Furthermore, the independent rear suspension 10 according to the present invention has a transverse leaf spring 42 for suspending the rear wheels 50 , 56 .

[0050] The transverse leaf spring 42 contains a composite material in a major proportion of more than 95% by volume. In this particular embodiment, the composite material is made of fiber-reinforced plastic. The fiber-reinforced plastic is implemented as glass-reinforced epoxy (GRE). The longitudinally constructed transverse leaf spring 42 is Figure 1 In the illustrated installed state, it lies in a plane (YZ plane) which is arranged perpendicular to the straight-ahead driving direction 68. The transverse leaf spring 42 has a substantially rectangular cross section which varies along its extension direction in order to achieve a predetermined spring characteristic curve.

[0051] The transverse leaf spring 42 is fixedly connected to the chassis of the motor vehicle by means of two spring clips 44 , 46 on either side of a central axis 70 of the motor vehicle.

[0052] Furthermore, the ends of the transverse leaf spring 42 are connected to the wheel-carrier-side ends of the semi-trailing arms 14, 28. In this case, the connection point between the transverse leaf spring 42 and the semi-trailing arms 14, 28 is spaced apart from the rotation axes 52, 58 of the rear wheels 50, 56 in the rearward direction. The connection of the end sides of the transverse leaf spring 42 to the wheel-carrier-side ends of the left and right semi-trailing arms 14, 28 is formed by two substantially vertically oriented connecting rods 24, 38, each of the loose bearings of the connecting rods 24, 38 being screwed to one end of the transverse leaf spring 42 and to the wheel-carrier-side end of one of the semi-trailing arms 14, 28. In this case, by means of the connecting rods 24, 38, a relative movement between the ends of the transverse leaf spring 42 and the respective ends of one of the semi-trailing arms 14, 28 on the wheel-carrier side is made possible within predetermined limits in the XY plane. In this way, the wheel-carrier-side ends of the semi-trailing arms 14, 28 are connected to the chassis of the motor vehicle in an elastic manner. Close to the connection point at the end of the transverse leaf spring 42 , means in the form of a groove 26 , 40 and a fastening hole for fastening a shock absorber (not shown) are provided on each semi-trailing arm 14 , 28 .

[0053] from Figure 1 It can be seen that the left trailing arm 14, the right trailing arm 28 and the transverse leaf spring 42 are arranged in such a way that an open installation space 12 is formed. The open installation space 12 is provided for receiving a part of an electric drive train 60 of a motor vehicle.

[0054] The electric drive train 60 of the motor vehicle comprises, among other things, an electric motor 62, a left drive shaft 64 and a right drive shaft 66, which are configured as articulated shafts. The electric motor 62 has an elongated shape and is arranged transversely to the straight-ahead driving direction in the open installation space 12, that is, in the central area of ​​the open installation space 12 between the semi-trailing arms 14, 28 and the transverse leaf spring 42, and is fixed to the chassis of the motor vehicle. Starting from either lateral side of the electric motor 62, each of the two drive shafts 64, 66 is arranged flush with one of the rotation axes 52, 58 of the rear wheels 50, 56, and the independent rear suspension 10 is in a state of statically carrying the chassis load. In addition, the two drive shafts 64, 66 are operably connected to one of the rear wheels 50, 56 for transmitting the driving torque. The articulated shaft is similar to the movement of the rear wheels 50, 56 relative to the electric motor 62 during the travel of the motor vehicle.

[0055] List of reference numerals:

[0056] 10 Independent rear wheel suspension

[0057] 12Open installation space

[0058] 14 Left semi-trailing arm

[0059] 16 Bushing

[0060] 18 Bushing

[0061] 20 Left pivot line

[0062] 22 grooves

[0063] 24 Connecting rod

[0064] 26 shock absorber grooves

[0065] 28 right semi-trailing arm

[0066] 30 Bushing

[0067] 32 Bushing

[0068] 34 Right pivot line

[0069] 36 grooves

[0070] 38 Connecting rod

[0071] 40 shock absorber grooves

[0072] 42 transverse leaf spring

[0073] 44 Spring Clip

[0074] 46 Spring Clip

[0075] 48 left wheel frame

[0076] 50 Left rear wheel

[0077] 52 Left rotation axis

[0078] 54 right wheel frame

[0079] 56Right rear wheel

[0080] 58 right rotation axis

[0081] 60 Electric Drivetrain

[0082] 62 Electric Motor

[0083] 64 Left drive shaft

[0084] 66 Right drive shaft

[0085] 68 straight driving direction

[0086] 70 Motor vehicle center axis

Claims

1. An independent rear suspension (10) for a motor vehicle with an electric drive system (60), comprising a left semi-trailing arm (14) and a right semi-trailing arm (28), each of which can be articulated to the chassis of the motor vehicle at an end on the vehicle body side and fixedly connected to the wheel frame at an end on the wheel frame side, and having a transverse leaf spring (42) for suspending the rear wheel, the electric drive system (60) comprising an electric motor (62), It is characterized in that The transverse leaf spring (42) is connected at the end side to the wheel carrier-side ends of the left semi-trailing arm (14) and the right semi-trailing arm (28), so that an open installation space (12) for receiving the electric motor (62) is formed between the left semi-trailing arm (14), the right semi-trailing arm (28) and the transverse leaf spring (42), and the electric motor (62) is fastened to the chassis of the motor vehicle.

2. The independent rear suspension (10) according to claim 1, It is characterized in that The position of the connection between the transverse leaf spring (42) and the left semi-trailing arm (14) and the right semi-trailing arm (28) is spaced apart from the rotation axis of the rear wheel in the rearward direction.

3. The independent rear suspension (10) according to claim 1 or 2, It is characterized in that The connection of the transverse leaf spring (42) to the wheel carrier-side ends of the left and right trailing arm halves (14 and 28) is formed by at least one substantially vertically oriented connecting rod or vertical shear pad unit.

4. The independent rear suspension (10) according to claim 1, It is characterized in that The ends of the left trailing arm (14) and the right trailing arm (28) on the wheel frame side are arranged below the rotation axis of the rear wheel, and the ends of the left trailing arm (14) and the right trailing arm (28) on the vehicle body side are arranged above the rotation axis.

5. The independent rear suspension (10) according to claim 1, It is characterized in that The vehicle body-side ends of the left trailing arm (14) and the right trailing arm (28) are fork-shaped and are provided with two separate bushings for being articulated to the chassis of the motor vehicle.

6. The independent rear suspension (10) according to claim 1, It is characterized in that A device for fastening a shock absorber element is provided at each end of the left semi-trailing arm (14) and the right semi-trailing arm (28) on the wheel carrier side.

7. The independent rear suspension (10) according to claim 1, It is characterized in that The transverse leaf spring (42) contains a major proportion of composite material.

8. A motor vehicle comprising: - an electric drive train (60) comprising an electric motor (62) and two drive shafts, and - Independent rear suspension (10) according to any one of claims 1 to 7, It is characterized in that The electric motor (62) is arranged in the open mounting space (12) between the left semi-trailing arm (14), the right semi-trailing arm (28) and the transverse leaf spring (42), and each of the two drive shafts is operatively connected to the rear wheels of the motor vehicle.

9. A motor vehicle according to claim 8, It is characterized in that The electric motor (62) is arranged in the central area of ​​the open installation space (12), and starting from either side of the electric motor (62), the two drive shafts are arranged flush with the rotation axis of any rear wheel.

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