DE102018121599A1 - Two-speed gearbox for an electrically drivable motor vehicle - Google Patents

Abstract

A two-speed transmission (10) for an electrically drivable motor vehicle is proposed with an input shaft (12) that can be connected to an electrical machine for introducing a torque, an output shaft (18) that can be connected to a drive wheel for deriving the torque, a first gear stage (14) for translating a speed of the input shaft (12) to the output shaft (18) with a first gear ratio, with a first driving gear (20) and a first driven gear (22), a second gear stage (16) for translating a speed the input shaft (12) to the output shaft (18) with a second gear ratio different from the first gear ratio, with a second driving gear (24) and a second driven gear (26), a freewheel, the first driving gear (20) or the is associated with the first driven gear (22) and a friction clutch (30) which drives the second plane gear (24) can connect to the output shaft (18). In order to be able to build the transmission smaller and more compact, it is proposed that this friction clutch (30) is provided as the only friction clutch (30) and that the freewheel (28) and the friction clutch (30) are both on the same shaft (12; 18) are arranged.

Description

The invention relates to a two-speed transmission for an electrically drivable motor vehicle, with the aid of which an output of an electrical machine can be converted. The invention is suitable for electrically assisted or purely electrically powered vehicles with batteries, that is to say for two-wheelers, such as bicycles, mopeds, scooters or motorcycles, for three-wheelers, such as rickshaws, or for vehicles with four wheels, from light vehicles to city buses .

When accelerating an electrically drivable motor vehicle from a standstill, an electrical machine can first accelerate from standstill with a substantially constant torque up to a basic speed. When the basic speed is reached, the drive power of the electrical machine remains essentially constant, so that the torque decreases for a higher speed. In order to achieve a large torque and speed spread, a two-speed transmission can be provided, which provides different transmission ratios. Thus, a high gear ratio can be provided in a low speed range in order to provide the highest possible torque for acceleration, while a low gear ratio can be provided in a high speed range in order to be able to implement the highest possible vehicle speed. Compared to direct drives or single-speed drives, two-speed gearboxes keep the engine in its most efficient range over long distances in every driving cycle. This also ensures lower consumption - and emissions if an internal combustion engine or a hybrid is also used.

From the EP 2 305 501 A1 A two-speed gearbox for electric vehicles is known, with an input shaft that can be connected to an electrical machine for introducing a torque, an output shaft that can be connected to a drive wheel for transmitting the torque, a first gear stage for translating a speed of the input shaft to the output shaft with a first transmission ratio a first driving gear and a first driven gear, a second gear stage for translating a rotational speed of the input shaft to the output shaft with a second gear ratio different from the first gear ratio, with a second driving gear and a second driven gear, a freewheel, the first driving gear or is associated with the first driven gear, and a friction clutch that can connect the second driven gear to the output shaft. However, this transmission contains two friction clutches to be operated and a separate locking ring, so that it is relatively large and the gear change is relatively complicated.

It is the object of the invention to show measures which lead to a smaller-sized and easier-to-use two-speed transmission in an electrically drivable motor vehicle.

The object is achieved according to the invention by a two-speed transmission with the features of claim 1. Preferred embodiments of the invention are specified in the subclaims and the following description, which can each represent an aspect of the invention individually or in combination.

According to the invention, a two-speed gearbox for electric vehicles is proposed, with an input shaft that can be connected to an electrical machine for introducing a torque, an output shaft that can be connected to a drive wheel for transmitting the torque, a first gear stage for translating a speed of the input shaft to the output shaft with a first transmission ratio, with a first driving gear and a first driven gear, a second gear stage for translating a rotational speed of the input shaft to the output shaft with a second gear ratio different from the first gear ratio, with a second driving gear and a second driven gear, a freewheel that drives the first Gear or the first driven gear is assigned, and a friction clutch that can connect the second driven gear to the output shaft, which friction clutch as ei only friction clutch is provided and the freewheel and the friction clutch are both arranged on the same shaft, that is to say in particular either the input shaft or the output shaft.

The two-speed transmission according to the invention has a simpler structure thanks to the absence of a second friction clutch and can therefore be made smaller. Eliminating the second friction clutch on the other shaft makes the transmission smaller, lighter, cheaper and less complex. Saving mass is advantageous. Shifting is easier since only a single clutch can be operated and a separate circlip system can be dispensed with. It was recognized that this simpler solution also enables smooth, jerk-free switching, which can preferably be carried out automatically. Since a freewheel is used, switching is smooth and seamless, whether it is mechanical or automatic. Since two or three elements cannot be operated when switching, one simple one is sufficient electronic or hydraulic actuator to change gears.

With the proposed invention, a battery-electric vehicle, which is also referred to as “BEV” (Battery Electric Vehicle), can be implemented, which switches automatically and offers many advantages with regard to reduced energy consumption, increased driving comfort, incline and maximum speed. Avoiding a shift gap in which a power flow is interrupted when changing gears increases performance and offers a superior driving experience. The inventive integration of freewheel and friction clutch leads to a smooth, smooth automatic shifting process. With the new transmission, the powertrain can be designed to be electrically smaller and still achieve high torque, which leads to a vehicle characteristic with high energy efficiency.

In particular, a control device can be provided which is designed to automatically change gear when a certain predefined threshold driving speed of the motor vehicle is exceeded and / or undershot and / or when a certain predefined threshold torque of the input shaft is exceeded and / or undershot. As a result, a suitable gear ratio can be switched automatically for the respective driving situation without the driver of the motor vehicle having to initiate this manually.

A multi-disc clutch can be used as the friction clutch, which automatically engages or disengages depending on the vehicle speed or the load conditions. This quickly synchronized soft engagement or disengagement leads to a "short" slip zone during the transition from first to second gear and thus a quick gear change. The clutch can be operated purely electrically.

During start-up and at low speeds, the new clutch mechanism fully opens and holds the only friction clutch so that the friction elements are separated and no power is transmitted. When the engine or vehicle speed increases, the vehicle switches to second gear, which is done by engaging the friction clutch and overtaking the freewheel, which no longer transmits power. During the upshift from first to second gear, the only friction clutch is actuated slowly, so it engages more and more until the torque transmitted by the clutch corresponds to the engine torque. The gear change is so smooth and without any jerk. Even if the engine torque is then reduced, the vehicle is in second gear in which the freewheel is overtaken or overrun.

Since the switching frequency is generally low and the first gear is actually only used for starting off or on the mountain, the second gear is usually engaged. Since, according to the invention, the only friction clutch does not have a long-lasting slip, but grips firmly, there is no risk of overheating in continuous operation. The thermal capacity of the friction clutch therefore does not have to be high, so that a smaller, relatively compact clutch can also be used. The fact that instead of two friction clutches only one friction clutch is provided and that this single friction clutch and the freewheel are arranged according to the invention on a single common shaft minimizes the space requirement of the transmission.

• - Langsam fahren, Anfahren oder Bergauffahren im ersten Gang
• - Schnell fahren im 2. Gang
• - Neutralstellung, beispielsweise beim Langsamer werden oder Bergabfahren, Segelmodus durch Öffnen der Reibungskupplung, und
• - Parkblockierstellung, insbesondere durch Eingreifen der Reibungskupplung bei ausgeschaltetem Motor.

The combination according to the invention of a freewheel, preferably of a roller lock, with a single friction clutch with the new clutch holding mechanism allows different operating modes with their different operating positions, namely:

• - Drive slowly, start off or go uphill in first gear
• - Driving fast in 2nd gear
• - Neutral position, for example when slowing down or driving downhill, sailing mode by opening the friction clutch, and
• - Parking blocking position, in particular by engaging the friction clutch when the engine is switched off.

The parking lock can be achieved in that when the vehicle and the engine have come to a standstill, the friction clutch is engaged and at the same time the freewheeling blocks a movement in the opposite direction. This saves a separate mechanism for the parking brake and an extra actuating element.

In the context of the invention, the clutch and the freewheel can be arranged on the input shaft or on the output shaft. However, it is preferred to provide the clutch and freewheel on the output shaft. Then the input shaft can be constructed in a particularly simple manner and contain the first driving gear and the second driving gear as fixed gears.

Clutch and freewheel can be arranged side by side on their common shaft. In a preferred embodiment, freewheel and friction clutch can be integrated in a common housing. Is particularly suitable if for this the clutch housing of the friction clutch is used. This results in a particularly space-saving, compact construction of the invention. The friction clutch, freewheel and the two driven gears then form a compact unit that takes up little space.

The freewheel is preferably integrated into the first driven gear, in that the hub of the freewheel is also the hub of the gear. This also leads to a particularly compact design.

The construction is even more space-saving and compact if the second driven gearwheel is located directly at the clutch, preferably on the side of the clutch actuation.

It is also particularly space-saving if the clutch housing is provided with a clutch housing profile, in particular spline teeth, and is arranged in a rotationally fixed manner on the output shaft in order to transmit torque to the output shaft.

When engaging and disengaging, the friction clutch can be operated like any other clutch known per se via manual, foot or actuator operation. Levers or cables can be used. Preferably, a release pin arranged centrally in the center of the clutch, for example a pin, can be provided, which can be engaged or released by pressing or releasing the clutch. Spring preloaded clutches are common, which are released when released - i.e. do not transmit torque - and grip with a pressed pin - i.e. transmit torque.

The pen can be operated directly via a cable or otherwise. However, a disengagement rod is preferably provided which has a flattened actuation surface and actuates or releases the disengagement pin when rotating about its longitudinal axis. This release rod is preferably actuated by means of a release lever, the release lever being moved back and forth by a linkage or a coupling cable, thereby rotating the release rod, which in turn presses or releases the release pin and thus actuates the clutch. This is an operating method that corresponds to the relatively short actuation travel and the rather high spring load of the release pin.

A clutch actuation mechanism is preferably provided, in which a slide is moved back and forth linearly in a slide rail, but engages in both end positions, so that the desired state of the clutch is held by itself and without effort.

This can be achieved by two components sliding on each other, e.g. a lower part and an upper part), whereby the desired position is maintained in both end positions without external force, as is known, for example, from the snap-in and snap-out mechanisms of ballpoint pens.

In a preferred embodiment, a ball / channel system is provided for this purpose, the channel being shaped in such a way that it has two locking points, in which one of the sliding parts rests without force from the outside and only moves to the other position after actuation to rest there again.

• 1: eine perspektivische Ansicht eines erfindungsgemäßen Zwei-Gang-Getriebes,
• 2: ein rotierendes Bauteil des Zwei-Gang-Getriebes aus 1,
• 3: eine Schnittansicht eines rotierenden Bauteils des Zwei-Gang-Getriebes aus 1,
• 4: eine perspektivische Ansicht des rotierenden Bauteils aus 3,
• 5: eine weitere Ansicht des Zwei-Gang-Getriebes aus 1,
• 6: den Kraftfluss eines erfindungsgemäßen Getriebes im ersten Gang,
• 7: den Kraftfluss eines erfindungsgemäßen Getriebes im zweiten Gang,
• 8: einen Kupplungsbetätigungsmechanismus am Zwei-Gang-Getriebe aus 1,
• 9: zwei Teile des Kupplungsbetätigungsmechanismus der 8,
• 10: den Schnitt AA der 9,
• 11: ein Unterteil des Kupplungsbetätigungsmechanismus der 8,
• 12 und 13: ein Oberteil des Kupplungsbetätigungsmechanismus der 8,
• 14: das Getriebe der 1 zusammen mit einem Motor im ersten Gang und
• 15: das Getriebe der 1 zusammen mit einem Motor im zweiten Gang.

In the following, the invention is explained by way of example with reference to the accompanying drawings using preferred exemplary embodiments, the features shown below being able to represent an aspect of the invention both individually and in combination. Show it:

• 1 1 shows a perspective view of a two-speed transmission according to the invention,
• 2 : a rotating component of the two-speed gearbox 1 .
• 3 : a sectional view of a rotating component of the two-speed transmission from 1 .
• 4 : a perspective view of the rotating component from 3 .
• 5 : Another view of the two-speed gearbox 1 .
• 6 : the power flow of a transmission according to the invention in first gear,
• 7 : the power flow of a transmission according to the invention in second gear,
• 8th : a clutch actuation mechanism on the two-speed transmission 1 .
• 9 : two parts of the clutch actuation mechanism of the 8th .
• 10 : the section AA of the 9 .
• 11 : a lower part of the clutch operating mechanism of the 8th .
• 12 and 13 : an upper part of the clutch operating mechanism of the 8th .
• 14 : the transmission of the 1 together with an engine in first gear and
• 15 : the transmission of the 1 together with an engine in second gear.

This in 1 illustrated two-speed transmission 10 has an input shaft 12 on, which can be rotatably connected to a motor shaft of an electrical machine of a motor vehicle. The input shaft 12 can have a first gear 14 and a second gear 16 with different gear ratios with an output shaft 18th be coupled to one with the output shaft 18th to drive the coupled drive wheel of the motor vehicle. The first gear 14 has a first driven gear 20th on that as a fixed gear on the input shaft 12 is arranged and with one with the output shaft 18th connected first driven gear 22 combs. The second gear 16 has a second driving gear 24 on that as a fixed gear on the input shaft 12 is arranged and with one with the output shaft 18th connected second driven gear 26 combs. On the output shaft 18th According to the invention, the freewheel is now located 28 and the only friction clutch 30th , The friction clutch has a central release pin for its actuation 32 on that over a release bar 34 and a release lever 36 can be operated.

2 shows a rotating component of the two-speed transmission 1 , namely the integrated unit from freewheel integrated according to the invention 28 , Friction clutch 30th and second driven gear 26 , It is easy to see that the freewheel 28 into the clutch housing 40 is integrated. The clutch housing profile can also be seen 42 , which is designed here as an internal toothing and torque on the output shaft 18th can transmit.

3 shows a sectional view of a rotating component of the two-speed transmission 1 , namely the combination of the in 2 shown rotating component from freewheel 28 and friction clutch 30th with the first driven gear 22 , The two needle bearings are also shown 58 and the intermediate ring 60 that together allow the two gears 22 and 26 with different speeds on the common shaft 18th can turn.

4 shows a perspective view of the rotating component 3 , taking a look at the springs of the clutch 30th is possible. The second driven gear 26 is integrated here in the area or on the side of the clutch actuation.

5 shows a further view of the two-speed transmission 1 , being on the output shaft 18th the driving role 44 is attached for deriving the torque.

To explain the function of the transmission according to the invention shows 6 the power flow in first gear. The motor M drives the input shaft 12 with the two fixed wheels 20th and 24 , The release lever 36 is pulled, so that is the release rod 34 twists and presses the release pin with its flattened operating surface 32 against the internal spring forces. So that is the friction clutch 30th open and does not transmit torque. The torque of the motor M flows through the first gears 20th and 22 , The gear 22 directs the rotary motion over the blocking freewheel 28 on the clutch housing 40 and there over the internal toothing of the clutch housing profile 42 on the output shaft 18th as the dotted line shows. That the inside of the clutch 30th rotates at a different speed than the clutch housing 40 , doesn't matter because the clutch 30th yes is open, so does not transmit a moment. This changes when shifting to second gear like it 7 shows:

7 shows the power flow of a transmission according to the invention in the "Super Boost" designated second gear. The motor M drives the input shaft 12 with the two fixed wheels 20th and 24 , The release lever 36 is released, so the release rod 34 turned back to its original position and presses the release pin with its flattened actuating surface 32 no longer against the internal spring forces. Due to this preload, the friction clutch is 30th now closed and transmits the torque. The torque of the motor M now flows through the friction clutch 30th from the second gears 24 and 26 into the clutch housing 40 and from there via the internal teeth of the clutch housing profile 42 on the output shaft 18th as the dotted line shows. The freewheel 28 is now overhauled because the speed is above the second gear of the gears 24 and 26 is faster than the speed of the first gear of the gears 20th and 22 , The freewheel 28 is driven from the outside - rolling over or overtaking - in contrast to the position in 6 , where the force or the torque come from inside, so use the locking effect. The inventive integration of freewheel 28 and clutch 30th on a wave 18th therefore leads to a very compact design. The slow engagement and the slow rolling over of the freewheel 20th lead to a smooth gear change without jerk.

8th shows a preferred clutch actuation mechanism 46 on the two-speed gearbox 1 , The mechanism 46 transmits the pulling force of a clutch actuation from the right to the clutch cable 38 and over this on the release lever 36 who in turn uses the release bar 34 and the release pin 32 actuated, and on the other hand holds the clutch cable 38 and with it the clutch 30th in the desired state "open" or "closed".

9 shows two components of the clutch actuation mechanism 46 the 8th , namely the lower part fixed to the gearbox 48 and the sliding top 50 the clutch cable 38 moved to the left and right (arrow). To hold in a desired one Position are two grooves 54 provided a groove 54 in the lower part 48 and the second groove in the top 50 are arranged. They are milled in a hemispherical shape and, when placed one on top of the other, result in a channel with a round cross-section, in which a ball 52 can be performed. The bullet 52 can now by pushing the top back and forth 50 on the lower part 48 are brought into two end positions, one end position via the coupling cable 38 to a fully open clutch 30th and the other end position to a completely closed clutch 30th leads.

10 shows the section AA of the 9 , whereby it can be clearly seen that when the upper part is correctly positioned 50 on the lower part 48 the two grooves 54 together a channel for the ball 52 surrender. The bullet 52 acts here as a locking or securing element and can the upper part 50 in two defined positions to the lower part 48 hold, similar to a mechanism in a ballpoint pen that can retract the pen tip and keep it extended. The white arrow indicates the direction of the tensile force of the clutch spring.

11 shows the lower part 48 of the clutch operating mechanism 46 the 8th , with the screws indicating that the lower part 48 is fixed and immovable on the housing of the transmission. The bullet 52 is in an end position in the groove 54 ,

The 12 and 13 show the top 50 of the clutch operating mechanism 46 the 8th , In the 12 is the top 50 shown from below, that is seen from the slide rail, which is the upper part 50 slidable but not removable on the lower part 48 holds. In 13 is the top 50 shown from above with a fastening option for a pulling or actuating element.

14 shows the transmission 10 the 1 together with an electric motor 56 in first gear, in which the engine torque 56 over the first gear 14 is transmitted. This is the top part 50 of the clutch operating mechanism 46 pulled to the left and blocked by an actuator (top left). This is also the release lever 36 in the left end position and holds the clutch 30th open.

15 shows the transmission 10 the 1 together with an electric motor 56 in second gear, in which the engine torque 56 over the second gear 16 is transmitted. This is the top part 50 of the clutch operating mechanism 46 pushed to the right and blocked by an actuator (top left). This is also the release lever 36 in its end position and holds the clutch 30th closed.

Reference list

10

Two-speed transmission

12th

Input shaft

14

first gear

16

second gear

18th

Output shaft

20th

first driving gear

22

first driven gear

24

second driving gear

26

second driven gear

28

Freewheel

30

Friction clutch

32

Release pin

34

Release bar

36

Release lever

38

Clutch cable

40

Clutch housing

42

Clutch housing profile

44

Drive roller

46

Clutch actuation mechanism

48

Lower part

50

Top

52

Bullet

54

groove

56

Electric motor

58

Needle bearing

60

Intermediate ring

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 2305501 A1 [0003]

Claims (10)

Two-speed gearbox for an electrically drivable motor vehicle with an input shaft (12) which can be connected to an electrical machine for introducing a torque, an output shaft (18) which can be connected to a drive wheel for deriving the torque, a first gear stage (14) for the translation of a speed the input shaft (12) to the output shaft (18) with a first gear ratio, with a first driving gear (20) and a first driven gear (22) of a second gear stage (16) for translating a speed of the input shaft (12) to the output shaft (18) with a second gear ratio different from the first gear ratio, with a second driving gear (24) and a second driven gear (26) a freewheel, which is assigned to the first driving gear (20) or the first driven gear (22), and a friction clutch (30) connecting the second driven gear (24) to the output gswelle (18), characterized in that this friction clutch (30) is provided as the only friction clutch (30) and that the freewheel (28) and the friction clutch (30) are both on the same shaft (12; 18) are arranged. Two-speed gearbox after Claim 1 , characterized in that the first driving gear (20) and the second driving gear (24) are fixed gears on a shaft, preferably the input shaft (12). Two-speed gearbox after Claim 1 or 2 , characterized in that the freewheel (28) is integrated in a clutch housing (40) of the friction clutch (30). Two-speed gearbox according to one of the Claims 1 to 3 , characterized in that the hub of the first driven gear (22) is also the hub of the freewheel (28). Two-speed gearbox according to one of the Claims 1 to 4 , characterized in that the second driven gear (26) is on the clutch actuation side. Two-speed gearbox according to one of the Claims 1 to 5 , characterized in that a clutch housing (40) of the friction clutch (30) is provided with a clutch housing profile (42) and is arranged in a rotationally fixed manner on the output shaft (18). Two-speed gearbox according to one of the Claims 1 to 6 , characterized in that a clutch is actuated by pressing a release pin (32) arranged centrally on the output shaft and in the middle of the clutch (30). Two-speed gearbox after Claim 7 , characterized in that a release rod (34) for actuating the release pin (32) is provided. Two-speed gearbox after Claim 7 or 8th , characterized in that a clutch actuation mechanism (46) is designed as a sliding mechanism. Two-speed gearbox after Claim 9 , characterized in that a channel formed from grooves (54) is provided for guiding a ball (52).

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