Patent Application
20210188077
The invention relates to a continuously variable power-split transmission with at least four driving ranges.
From DE 195 22 833 A1 a continuously variable power-split transmission with a mechanical power branch and with a hydrostatic power branch is known. The power branches are driven by a common driveshaft and are summed by a mechanical linkage. The mechanical linkage comprises a plurality of planetary gearsets and clutches, and is connected to a drive output shaft. In this case the mechanical linkage is arranged on a drive input shaft. One of the planetary gearsets of the mechanical linkage can be brought into functional connection with the drive output shaft by means of drive direction clutches for forward driving and driving in reverse.
A further planetary gearset of the mechanical linkage comprises three simple three-shaft planetary transmissions and in the area of five shafts is connected to the transmission input shaft, to a variator of the hydrostatic power branch and to shifting element halves of the clutches, and can be coupled by way of the clutches to the one planetary gearset.
However, the known power-split transmission is characterized by much cost and effort for design and construction. Due to undesirably high reactive power flows in the area of the mechanical linkage, during the operation of the power-split transmission power losses occur which have an adverse effect on the efficiency of the power-split transmission.
Accordingly, the purpose of the present invention is to provide a simply designed, continuously variable power-split transmission that can be operated with high efficiency.
According to the invention, this objective is achieved with a continuously variable power-split transmission having the characteristics specified in the independent claim(s).
The continuously variable power-split transmission according to the invention is designed with at least four driving ranges, in which the gear ratio in the area of a variator can be varied continuously. A first planetary gearset comprising a plurality of shafts can be connected by way of a plurality of shifting elements to a second planetary gearset which has a plurality of shafts and is or can be functionally connected to a transmission output shaft.
According to the invention, the first planetary gearset has four shafts and by way of a first shaft is or can be brought into functional connection with a transmission input shaft and a first shaft of the variator. In addition, the first planetary gearset is functionally connected by a second shaft to a second shaft of the variator, while the first planetary gearset is coupled by a third shaft to shifting element halves of two shifting elements and by a fourth shaft to a shifting element half of a further shifting element.
By virtue of the connection according to the invention of the first planetary gearset to the transmission input shaft, the variator and the shifting elements, the continuously variable power-split transmission according to the invention can be constructed in a simple manner with a first planetary gearset that has only four shafts. Compared with the solution known from the prior art, the first planetary gearset can be made less expensively and reduced need of fitting space, and in addition low reactive power flows occur in a first planetary gearset designed in this way.
To obtain the four driving ranges as compactly and inexpensively as possible, in a further development of the continuously variable power-split transmission according to the invention, the third shaft of the first planetary gearset can be connected by way of the shifting element with whose shifting element half the third shaft of the first planetary gearset is coupled, to a first shaft of the second planetary gearset. Furthermore, for that purpose the third shaft of the first planetary gearset can be functionally connected to a second shaft of the second planetary gearset by way of the second shifting element, with whose shifting element half the third shaft of the first planetary gearset is also coupled.
In another cost and fitting-space saving embodiment of the continuously variable power-split transmission according to the invention, the fourth shaft of the first planetary gearset can be coupled by way of the further shifting element to the first shaft of the second planetary gearset and to a shifting element half of an additional shifting element. Moreover, the fourth shaft of the first planetary gearset can be functionally connected with the second shaft or with the third shaft of the second planetary gearset by way of the additional shifting element.
In an embodiment of the continuously variable power-split transmission that is alternative to the above and is also economical and fitting space-saving, the fourth shaft of the first planetary gearset can be coupled by means of the further shifting element to the first shaft of the second planetary gearset, while the second shaft of the second planetary gearset can be functionally connected to the third shaft of the second planetary gearset by an additional shifting element.
If the second shaft of the second planetary gearset can be connected by a shifting element to a component fixed on the housing in a rotationally fixed manner, at least two of the four driving ranges can be obtained with high efficiency in a simply designed manner at the same time as occupying little fitting space.
In the area of the transmission input shaft, in a further development of the continuously variable power-split transmission according to the invention a shifting element is provided by way of which a drive machine of a vehicle drive-train built with the power-split transmission, that can be coupled to the transmission input shaft, can be brought into functional connection with or decoupled from the first shaft of the first planetary gearset. Thus, in a simply designed manner it is made possible not to apply to the transmission input shaft drag torques from the drive machine during driving operation of a vehicle built with the continuously variable power-split transmission according to the invention, while the drive machine that can be brought into functional connection with the transmission input shaft is switched off.
If the transmission input shaft is functionally connected to an electric machine, some of the torque applied to the transmission input shaft can be used to generate electrical energy if the electric machine can be operated as a generator. The electrical energy produced by the electric machine can for example be made available for supplying an on-board network of a vehicle built with the continuously variable power-split transmission according to the invention, for charging an electric accumulator, and/or for driving an electric machine. Furthermore, while the electric machine is being operated as a motor, purely electric driving operation of a vehicle built with the power-split transmission according to the invention can be obtained, while the torque from the electric machine alone is made available at the drive output and/or in the area of a power take-off shaft. In addition it is also made possible, during a so-termed boost operation, at the same time to apply torque from the electric machine and from a drive machine such as an internal combustion engine of a vehicle drive-train that can also be coupled to the transmission input shaft, in the area of the drive output and/or a power take-off shaft.
In such a case it can be provided that during its motor operation, the electric machine can be supplied with electrical energy from an electric storage device on the vehicle and/or from an external power supply such as a power network. For that purpose a vehicle can be made, for example, with an appropriate interface such as a power socket and/or a plug, in order to be able to connect the vehicle or its electric machine to the power network to the extent desired.
The generator can be connected directly to the transmission input shaft in a simply designed manner at the same time as losses remain low.
If the electric machine is coupled to the transmission input shaft via at least one spur gear stage and/or via at least one planetary gearset, the torque to be used for driving the generator or to be made available is lower than when the generator is connected directly to the transmission input shaft. Otherwise, however, the couplings with gearwheel stages are characterized by higher mechanical effort and, during operation, by higher mechanical power loss. Since as is known, electric machines can be operated more efficiently at higher rotational speeds than in the lower rotational speed ranges, the power-split transmission according to the invention can be operated with greater overall efficiency with appropriate design of the gear ratio of the at least one spur gear stage or the at least one planetary gear system and the electric machine, compared to direct connection of the electric machine to the transmission input shaft.
If the continuously variable power-split transmission comprises two driving-direction clutches that can be switched into and out of the force flow, and the gearwheel pairs associated with them, a vehicle built with the power-split transmission according to the invention can be operated both in the forward-driving and in the reverse-driving direction. In that case a rotational direction of the transmission output shaft when the first driving-direction clutch is engaged corresponds to the rotational direction of the transmission input shaft. In contrast, if the second driving-direction clutch is engaged the rotational direction of the transmission output shaft is different from the rotational direction of the transmission input shaft. Furthermore, the transmission input shaft can be functionally connected via the driving-direction clutches with the first shaft of the first planetary gearset, or the transmission output shaft can be functionally connected via the driving-direction clutches with the second planetary gearset. In one arrangement the driving-direction clutches in the force flow between the transmission input shaft and the first shaft of the first planetary gearset are made smaller than in an arrangement in the force flow of the transmission between the second planetary gearset and the transmission output shaft.
In order to adapt the continuously variable power-split transmission to a fitting space available in a vehicle, in further embodiments of the continuously variable power-split transmission according to the invention the driving-direction clutches are arranged in the area of the functional connection between the transmission input shaft and the first planetary gearset or in the area of the functional connection between the second planetary gearset and the transmission output shaft.
If the variator is in the form of a hydraulic variator with two hydraulic machines, in which the displacement volume of at least one of the hydraulic machines can be varied, the power-split transmission according to the invention is characterized by a high power density.
In an alternative embodiment of the continuously variable power-split transmission according to the invention that can be operated with high efficiency, the variator is in the form of an electric variator with two electric machines. In this case the possibility exists of operating the electric machine of the variator that is functionally connected to the transmission input shaft over the full operating range of the transmission, in the case of direct coupling to the transmission input shaft, respectively at the rotational speed of the drive machine, or if the electric machine is connected via a gear system, at a rotational speed that corresponds to the rotational speed of the drive machine. In contrast, the rotational speed of the other electric machine coupled to the second shaft of the first planetary gearset can be varied continuously in order to adjust the gear ratio of the power-split transmission according to the invention, independently of the rotational speed of the transmission input shaft.
In space-saving embodiments of the continuously variable power-split transmission according to the invention the variator, by way of its first shaft, is functionally connected to the first shaft of the first planetary gearset directly, via spur gearwheels and/or via a planetary gearset, and by way of its second shaft, it is functionally connected via spur gearwheels and/or via a planetary gearset to the second shaft of the first planetary gearset.
In this case, if the variator is connected directly to the transmission input shaft and/or to the second shaft of the first planetary gearset, the variator must be made larger, since the torque applied by the transmission input shaft and by the second shaft of the first planetary gearset, respectively, is greater than when the variator is connected to the transmission input shaft and to the second shaft by way of spur gearwheels and/or the planetary gearset. In contrast, however, fitting space is also needed for the additional spur gearwheels and/or the additional planetary gearset, which is sometimes made available due to the then possible smaller size of the variator. The choice of which way to connect the variator to the transmission input shaft and to the second shaft of the first planetary gearset is made as a function of the application case at the time and of the fitting space available in the vehicle.
If the first planetary gearset, the second planetary gearset, the driving-direction clutches, the shifting elements and/or the variator are arranged coaxially with one another, the continuously variable power-split transmission is characterized in that it needs little fitting space in the radial direction.
In embodiments of the continuously variable power-split transmission according to the invention which require little fitting space in the axial direction, the first planetary gearset, the second planetary gearset, the driving-direction clutches, the shifting elements and/or the variator are radially offset relative to one another and are arranged on countershafts a distance apart from one another. These embodiments are characterized by the need for more fitting space in the radial direction than the coaxial arrangement of the assemblies of the power-split transmission.
If the variator is arranged in the axial direction between the transmission input and the first planetary gearset, coaxially with the first planetary gearset, or in the radial direction offset relative to the first planetary gearset, then the shafts of the variator can be made shorter in the axial direction. In that way deflections between support points in the area of the variator shafts are small.
In a further embodiment of the continuously variable power-split transmission according to the invention that can be designed in a space-saving manner, the second shaft of the first planetary gearset, in the axial direction, is connected between the transmission input and the first planetary gearset to the second shaft of the variator, while the first shaft of the variator is functionally connected to the first shaft of the first planetary gearset in the axial direction between the second planetary gearset and the transmission output.
In a further development of the continuously variable power-split transmission according to the invention characterized by little fitting space requirement, the driving-direction clutches are radially offset relative to one another and are preferably arranged in a common plane in the axial direction.
The continuously variable power-split transmission according to the invention can be integrated into various existing vehicles in a simple manner, if the transmission input and the transmission output are arranged on the same side or in the axial direction on different sides.
In an embodiment of the continuously variable power-split transmission according to the invention that can be operated with high efficiency, the first planetary gearset comprises a stepped planetary gear assembly. In this case the first shaft of the first planetary gearset is connected to a sun gear of the stepped planetary gear assembly, the second shaft of the first planetary gearset to a ring gear of the stepped planetary gear assembly, the third shaft of the first planetary gearset to a planetary carrier of the stepped planetary gear assembly and the fourth shaft of the first planetary gearset to a further sun gear of the stepped planetary gear assembly. On the planetary carrier stepped planetary gearwheels are arranged and can rotate, which in a larger diameter range mesh with the ring gear and the further sun gear, whose diameter is in turn smaller than the diameter of the sun gear. Furthermore, The planetary gearwheels with a smaller diameter range engage with the sun gear. By using such a stepped planetary gear assembly, no, or only little reactive power circulates in the area of the first planetary gearset, so the transmission according to the invention can be operated with high efficiency.
For that purpose, in an embodiment of the continuously variable power-split transmission according to the invention that can be produced with little cost and effort, the first planetary gearset comprises two ring gears, a sun gear and a planetary carrier, with a plurality of planetary gearwheels mounted to rotate on the planetary carrier. In this, at least a first planetary gearwheel meshes with one of the ring gears and with at least one second planetary gearwheel, while the at least one second planetary gearwheel is engaged with the other ring gear and the sun gear. The first shaft of the first planetary gearset is connected to one of the rings gears, the second shaft of the first planetary gearset is connected to the other ring gear, the third shaft of the first planetary gearset to the planetary carrier and the fourth shaft of the first planetary gearset to the sun gear.
If the first planetary gearwheel and the second planetary gearwheel are arranged offset from one another in the axial direction and mounted to rotate on the same diameter, and if they have the same number of teeth as the ring gears, the rotational speed of the second shaft of the first planetary gearset can be varied continuously in all the driving ranges within a section range that is symmetrical relative to the zero-point of the rotational speed of the second shaft.
In an embodiment of the continuously variable power-split transmission according to the invention that is also simple to produce, the first planetary gearset comprises two simple planetary gear assemblies each having a ring gear, a planetary carrier with planetary gearwheels mounted to rotate on it, and a sun gear. The first shaft of the first planetary gearset is in this case connected to the planetary carrier of the first simple gear assembly and the second shaft of the first planetary gearset is connected to the sun gear of the first simple planetary gear assembly and to the ring gear of the second simple planetary gear assembly. In addition, the third shaft of the first planetary gearset is functionally connected to the planetary carrier of the second simple planetary gear assembly and the fourth shaft of the first planetary gearset is functionally connected to the sun gear of the second simple planetary assembly and to the ring gear of the first simple gear assembly.
The last-described embodiment of the continuously variable power-split transmission according to the invention is characterized in that it occupies little space in the axial direction if the first simple planetary gear assembly is arranged radially inside the second simple planetary gear assembly.
A further embodiment of the continuously variable power-split transmission according to the invention that can be produced simply is formed with a first planetary gearset that comprises two simple planetary gear assemblies, each with a ring gear, a planetary carrier with planetary gearwheels mounted to rotate on it, and a sun gear. The first shaft of the first planetary gearset is connected to the planetary carrier of the first simple planetary gear assembly. The second shaft of the first planetary gearset is functionally connected to the ring gear of the second simple planetary gear assembly. In addition the third shaft of the first planetary gearset is connected to the planetary carrier of the second simple planetary gear assembly and to the ring gear of the first simple planetary gear assembly. Moreover, the fourth shaft of the first planetary gearset is coupled to the sun gear of the second simple planetary gear assembly and to the sun gear of the first simple planetary gear assembly.
In a further space-saving embodiment of the continuously variable power-split transmission according to the invention that can be produced inexpensively, the first planetary gearset comprises a Ravigneaux gearset. The first shaft of the first planetary gearset is coupled to a planetary carrier of the Ravigneaux gearset. The second shaft of the first planetary gearset is functionally connected to a sun gear of the Ravigneaux gearset, while the third shaft of the first planetary gearset is connected to a ring gear of the Ravigneaux gearset. Moreover, the fourth shaft of the first planetary gearset is functionally connected to a further sun gear of the Ravigneaux gearset. In this case the sun gear has a smaller diameter than the further sun gear.
In a further, space-saving embodiment of the continuously variable power-split transmission according to the invention that can be produced inexpensively, the first planetary gearset of the power-split transmission comprises a planetary gear assembly with two ring gears, with a planetary carrier and with one sun gear. A plurality of planetary gearwheels are mounted to rotate on the planetary carrier. Some of the planetary gearwheels are made with a larger axial length than the rest of the planetary gearwheels. The longer planetary gearwheels mesh with the one of the ring gears, the sun gear and the shorter planetary gearwheels, while the shorter planetary gearwheels engage with the longer planetary gearwheels and with the other ring gear. One ring gear is made with a smaller diameter than the other ring gear an is surrounded radially by the larger ring gear.
In this case, in a simply designed further development of the last-described embodiment of the power-split transmission that can be produced inexpensively, the first shaft of the first planetary gearset is connected to the planetary carrier while the second shaft of the first planetary gearset is coupled to the sun gear. In addition the third shaft of the first planetary gearset is functionally connected to the larger ring gear and the fourth shaft of the first planetary gearset is coupled to the smaller ring gear.
A further development of the continuously variable power-split transmission comprises a second planetary gearset in the form of a simple planetary assembly. In this case the first shaft of the second planetary gearset forms the sun gear, the second shaft of the second planetary gearset forms the ring gear and the third shaft of the second planetary gearset forms the planetary carrier, with planetary gearwheels mounted to rotate on the planetary carrier.
Both the characteristics specified in the claims and those indicated in the following description of example embodiments of the continuously variable power-split transmission according to the invention are in each case suitable, whether as stand-alone features or in any combination with one another, as further developments of the object of the invention.
Further advantages and advantageous embodiments of the continuously variable power-split transmission according to the invention emerge from the claims and from the example embodiments whose principles are described in what follows with reference to the drawing. In the description of the various example embodiments, for the sake of clarity the same indexes are used for structurally and functionally equivalent components.
The first planetary gearset P1 is functionally connected by way of a first shaft W11 to a transmission input shaft 7 and a first shaft 8 of the variator 5. Furthermore, the first planetary gearset P1 is connected by a second shaft W12 to a second shaft 9 of the variator 5. In addition the first planetary gearset P1 is coupled by a third shaft W13 to shifting element halves 10, 11 of the shifting elements K1 and K3 and by a fourth shaft W14 to a shifting element half 12 of a further shifting element K2.
The third shaft W13 of the first planetary gearset P1 can be functionally connected via the shifting element K1 with a first shaft W21, in the form of a sun gear, of the second planetary gearset P2 and by means of the further shifting element K3 with a second shaft W22 of the second planetary gearset P2.
Moreover, the fourth shaft W14 of the first planetary gearset P1 can be coupled by the further shifting element K2 to the first shaft W21 of the second planetary gearset P2 and to a shifting element half 13 on the transmission input side of an additional shifting element K4, whose shifting element half 78 on the transmission output side is connected to a third shaft W23 of the second planetary gearset P2. Thus, the fourth shaft W14 of the first planetary gearset P1 can be functionally connected via the additional shifting element K4 with the third shaft W23 of the second planetary gearset P2.
In the present case the second planetary gearset P2 can be functionally connected via the driving-direction clutches KV and KR, by way of its third shaft W23 which is in the form of a planetary carrier, with the transmission output shaft 6.
In the present case the third shaft W23 of the second planetary gearset P2 is connected in a rotationally fixed manner to a common shifting element half 14 of the driving-direction clutches KV and KR. If both driving-direction clutches KV and KR are open, the functional connection between the third shaft W23 of the second planetary gearset P2 and the transmission output shaft 6 is separated. For the case when the driving-direction clutch KV for forward driving is closed and the driving-direction clutch KR for reverse driving is at the same time in its fully open operating condition, a loose wheel 15 arranged to rotate on the third shaft W23 of the second planetary gearset P2 is connected to the third shaft W23. The loose wheel 15 meshes with a fixed wheel 16 of a countershaft 17, which is made with a further fixed wheel 18.
The further fixed wheel 18 in turn meshes with a fixed wheel 19 of the transmission output shaft 6, which in the example embodiment of the vehicle drive-train 1 shown in
Otherwise than as above, the transmission output shaft 6 can be coupled to one or more drivable vehicle axles in other suitable ways. The connection between the transmission output shaft 6 and such drivable vehicle axles can be formed by means of a central differential with an associated bridging clutch or other suitable coupling devices. In the area of the central differential power-splitting takes place between two drivable vehicle axles without any additional control and regulation complexity, wherein the power-splitting of the central differential can be deactivated by means of the bridging clutch with little complexity.
Furthermore, it is possible to connect to one another two drivable axles that can be brought into functional connection with the transmission output shaft 6, and in that way to provide a permanent all-wheel drive or to couple only one drivable vehicle axle, preferably the rear axle of the vehicle, with the transmission output shaft.
Depending on the respective application at hand, the drivable vehicle axle functionally connected to the transmission output shaft 6 by means of the bevel gear 20 can be a vehicle rear axle or a vehicle front axle and the drivable further vehicle axle functionally connected to the countershaft 23 can be the vehicle front axle or the vehicle rear axle.
The first shaft 8 of the variator 5 is, in the present case, functionally connected to the transmission input shaft 7 by way of a fixed wheel 24 of the first shaft 8 of the variator 5, an intermediate gearwheel 25 that meshes with it and a fixed wheel 26 of the transmission input shaft 7 that engages with the gearwheel 25. For that purpose, starting from the transmission input 27 the transmission input shaft 7 extends, in the axial direction of the continuously variable power-split transmission 3 as far as the transmission output 28 and, depending on the respective application at hand, also beyond the drivable vehicle axle arranged in the area of the transmission output 28 in the axial direction of the vehicle drive-train 1. In addition. the transmission input shaft 7 can be brought, in the area of the transmission output 28 in a manner known as such, into functional connection with a so-termed power take-off (PTO) shaft via a PTO transmission, by way of which so-termed attachment devices of the vehicle made with the vehicle drive-train 1 can be acted upon by or supplied with torque from the drive machine 2.
The second shaft 9 of the variator 5 is in the present case functionally connected via a gearwheel 29 connected in a rotationally fixed manner to the second shaft W12 of the first planetary gearset P1 and a fixed wheel 30 of the second shaft 9 of the variator 5 that meshes with it. In addition, the second shaft W22 of the second planetary gearset P2, which shaft is in the form of a ring gear, can be made rotationally fixed or fixed to the housing by means of a shifting element B in the form of a brake when the shifting element B is in its closed operating condition.
In the example embodiment of the power-split transmission 3 shown in
To obtain the first driving range, within which the gear ratio of the power-split transmission 3 is highest and by virtue of which the largest traction force can be delivered, the first shifting element K1 and the further shifting element B must be closed whereas the other shifting elements K2 to K4 must be changed to their open operating condition. To be able to engage the second driving range in the power-split transmission 3, which follows on from the first driving range, the two shifting elements K2 and B must be closed, whereas the shifting elements K1, K3 and K4 must be changed to or kept in their open operating condition.
The third driving range in the power-split transmission 3, which in turn follows on from the second driving range, is engaged when the two shifting elements K2 and K3 are closed and the shifting elements K1, K4 and B are in their open operating condition. The fourth driving range, which follows on from the third driving range, is then engaged in the power-split transmission 3 when the shifting elements K1, K3 and B are open and the shifting elements K2 and K4 are closed at the same time. The vehicle made with the vehicle drive-train 1 is operated in the forward driving direction regardless of which of the four driving ranges in the power-split transmission 3 is engaged, when the driving-direction clutch KV is closed and the driving-direction clutch KR is open. In contrast, such a vehicle is operated in the reverse driving direction when the driving-direction clutch KR is closed and the other driving-direction clutch KV is open.
The first planetary gearset P1, the shifting elements K1 to K4, the second planetary gearset P2, the shifting element B and the driving-direction clutches KV and KR are in the present case all arranged coaxially with one another on the transmission input shaft 7, so that in the radial direction the power-split transmission 3 demands little fitting space.
Furthermore, the first planetary gearset P1 comprises a stepped planetary gear assembly. In this case the first shaft W11 of the first planetary gearset P1 is connected to a sun gear SR1 of the stepped planetary gear assembly. The second shaft W12 of the first planetary gearset P1 is functionally connected to a ring gear HR of the stepped planetary gear assembly, while the third shaft W13 of the first planetary gearset P1 is coupled to a planetary carrier PT of the stepped planetary gear assembly, on which stepped planetary gearwheels PR are mounted to rotate. The fourth shaft W14 of the first planetary gearset P1 is connected to a further sun gear SR2 of the stepped planetary gear assembly.
The stepped planetary gearwheels PR mesh in a larger diameter area PR2 with the ring gear HR and the further sun gear SR2, whose diameter is smaller than the diameter of the sun gear SR1. Moreover, the planetary gearwheels PR engage in an area of smaller diameter PR1 with the sun gear SR1.
In the example embodiment shown in
In contrast to the two embodiments of the power-split transmission 3 shown in
The example embodiment of the vehicle drive-train 1 shown in
The first shaft W11 of the first planetary gearset P1 is connected to the first ring gear HR1. The second shaft W12 of the first planetary gearset P1 is coupled rotationally fixed to the other ring gear HR2, while the third shaft W13 of the first planetary gearset P1 is connected rotationally fixed to the planetary carrier PT. The fourth shaft W14 of the first planetary gearset P1 is in turn connected to the sun gear SR. In the first planetary gearset P1 shown in
The first planetary gearset P1 of the example embodiment of the vehicle drive-train 1 shown in
The vehicle drive-train 1 shown in
The example embodiment of the vehicle drive-train 1 shown in
In the embodiment of the vehicle drive-train 1 shown in
For that purpose the loose wheel 33 and the fixed wheel 18 mesh with a fixed wheel 72 connected to the countershaft 31 in a rotationally fixed manner. The countershaft 31 can be coupled to the transmission output shaft 6 by way of the first planetary gearset P1, the shifting elements K1 to K4 and the second planetary gearset P2. In this case the transmission output shaft 6 is functionally connected, via a fixed wheel 34 and a fixed wheel 35 of the third shaft 23 of the second planetary gearset P2 that meshes with it, to the third shaft 23 of the second planetary gearset P2.
In the example embodiment of the vehicle drive-train 1 shown in
Basically, when the variator 5 is made as an electric variator the possibility exists of supplying electrical energy to other electric consumers, such as an additional electric machine EM3, an additional electric accumulator 46 and an on-board electric system 47, in a simple manner by means of an appropriate regulation and control system 48. In such a case the regulation and control ability can be better realized by comparison with a hydraulic variator.
In addition the possibility exists, that during operation in the motor mode by virtue of the on-board electric accumulator 46 and/or via an external current supply such as a power network or the like, the electric machines EM1 and EM2 can be supplied with electrical energy. For that purpose a vehicle can for example be made with a corresponding interface such as a power socket and/or a plug, in order to be able to connect the vehicle or its electric machines EM1, EM2 to the external power source to the desired extent.
The further example embodiment of the vehicle drive-train 1 shown in
Compared with the direct connection to the transmission input shaft 7 and the second shaft W12 of the first planetary gearset P1, shown in
Furthermore, during the operation of the vehicle drive-train 1 while the drive machine 2 is stationary, for example at a rotational speed equal to 2000 r/min, the first electric machine EM1 can be operated at a constant rotational speed which, with a corresponding gear ratio of the planetary gearset PEM1, is for example around 6000 r/min. In contrast, the rotational speed of the second electric machine EM2 in the last-described numerical example is then continuously varied between a first rotational speed, for example −6000 r/min and a second rotational speed, for example +6000 r/min. Thereby, the overall gear ratio of the power-split transmission 3 within the driving range engaged at the time can be changed continuously to the desired extent along with a high efficiency of the electric machines EM1 and EM2.
Compared with a hydraulic variator the electric variator 5 can be operated with greater efficiency, but the electric variator 5 is characterized by lower power density and at present incurs higher manufacturing costs than the use of a hydraulic variator.
A further example embodiment of the vehicle drive-train 1 is shown in
In this embodiment of the two planetary gearsets PEM1 and PEM2, during the operation of the vehicle drive-train 1 no centrifugal forces act upon the planetary gearwheels 44 or 45 arranged to rotate on the planetary carriers, 42 and 43, respectively. Compared with the structure of the vehicle drive-train 1 according to
A further example embodiment of the vehicle drive-train 1 is shown in
Due to the transmission-input-side arrangement of the driving-direction clutches KV and KR, these are again made smaller than if the driving-direction clutches KV and KR had been arranged on the transmission output side. In addition, in the embodiment shown in
In the example embodiment of the vehicle drive-train 1 shown in
In the embodiment of the vehicle drive-train 1 shown in
In contrast to this, the power density of the electric machines EM1 and EM2 used in the example embodiments according to
In the embodiment of the vehicle drive-train 1 shown in
An example embodiment characterized by occupying little fitting space in the axial direction is shown in
In addition the transmission input shaft 7 can be connected in a rotationally fixed manner by means of the driving-direction clutch KV to the loose wheel 15, which meshes with the fixed wheel 18 of the countershaft 17. The further fixed wheel 18 of the countershaft 17 engages with a fixed wheel 59 of the countershaft 31, so that a torque applied to the transmission input shaft 7 can be transmitted to the countershaft 31 by way of the gear chain comprising the driving-direction clutch KV and the gearwheels 15, 16, 18 and 59.
If the vehicle made with the vehicle drive-train 1 according to
Depending on the application case at the time, it is also possible that the transmission output shaft 6 is or can be brought into functional connection with one or more drivable vehicle axles by way of further gearwheel stages.
The vehicle drive-train 1 shown in
The second electric machine EM2 is arranged in the axial direction on the side of the second planetary gearset P2 facing away from the drive machine 2. Compared with the embodiment of the vehicle drive-train 1 according to
In the vehicle drive-train 1 shown in
The loose wheel 33 arranged together with the driving-direction clutch KR for reverse driving on the transmission input shaft 7, when the driving-direction clutch KR is in its closed condition, is connected rotationally fixed to the transmission input shaft 7 and meshes with the fixed wheel 59 of the countershaft 31. The loose wheel 15 associated with the driving-direction clutch KV for forward driving, when the driving-direction clutch KV is in its closed condition, is connected rotationally fixed to the fixed wheel 18, which is also engaged with the fixed wheel 59 of the countershaft. The loose wheel 15 meshes with a fixed wheel 73 of the transmission input shaft 7.
An embodiment of the vehicle drive-train 1 extended by a further shifting element K0 of the power-split transmission 3 compared with the embodiment of the vehicle drive-train 1 shown in
In addition, the possibility exists of arranging the shifting element K0 and the planetary gearset PEM1, again in a space-saving manner, radially within the first electric machine EM1 of the variator 5.
The additional shifting element K0 offers the possibility of enabling a vehicle made with the vehicle drive-train 1 according to
A further example embodiment of the vehicle drive-train 1 is shown in
In the further example embodiment of the vehicle drive-train 1 shown in
A further development of the vehicle drive-train 1 shown in
In contrast to the above, in the further example embodiment of the vehicle drive-train 1 shown in
On the planetary carrier PT, a total of six planetary gearwheels PR11 and PR21 are mounted to rotate. In the present case three planetary gearwheels PR11 have a longer axial length than three other planetary gearwheels PR21. The longer planetary gearwheels PR11 mesh with the ring gear HR, the further sun gear SR2 and the shorter planetary gearwheels PR21. The shorter planetary gearwheels PR21 also engage with the smaller sun gear SR1.
The configuration of the first planetary gearset P1 with a Ravigneaux gearset has the advantage that the continuously variable power-split transmission 3 can be produced less expensively and takes up less fitting space, since the Ravigneaux gearset has only one web or planetary carrier PT and one ring gear HR.
A further embodiment of the vehicle drive-train 1 is shown in
On the planetary carrier PT are preferably mounted to rotate a total of six planetary gearwheels PR11 and PR21. Three planetary gearwheels PR11 are in this case axially longer than three other planetary gearwheels PR21. The longer planetary gearwheels PR11 mesh with the ring gear HR2, the sun gear SR and the shorted planetary gearwheels PR21. In addition the shorter planetary gearwheels PR21 engage with the other ring gear HR1. The ring gear HR2 has a smaller diameter than the ring gear HR1, and is surrounded radially by the larger ring gear HR1
The first shaft W11 of the first planetary gearset P1 is connected to the planetary carrier PT, while the second shaft W12 of the first planetary gearset P1 is functionally connected to the sun gear SR. In addition the third shaft W13 of the first planetary gearset P1 is coupled to the larger ring gear HR1 and the fourth shaft W14 of the first planetary gearset P1 is connected to the smaller ring gear HR2.
Besides the assemblies of the vehicle drive-train 1 according to
Basically, all the example embodiments of the vehicle drive-train 1 or its continuously variable power-split transmission 3 shown in the drawing can be produced with a first planetary gearset P1 designed in accordance with
In addition, there is also the possibility that the different shifting elements are implemented as positive and/or frictional shifting elements, i.e. as claw shift elements, as synchronizers or as multi-plate clutches or multi-plate brakes. In addition, it can also be provided that changes between the driving ranges with low loads on the shifting elements K1 to K4 and B are carried out essentially synchronously.
Reversing processes too, of a vehicle built with a vehicle drive-train 1 can be assisted or carried out by appropriate actuation of the two driving-direction clutches KV and KR. In that connection it should also be pointed out that the mode of action of the two driving-direction clutches KV and KR can deviate from the mode of action described earlier, depending on the configuration of the vehicle drive-train 1 chosen, to the extent that a vehicle built with the vehicle drive-train 1 is driven in the reverse direction when the driving-direction clutch KV is closed and in the forward direction when the driving-direction clutch KR is closed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 219 999.7 | Nov 2017 | DE | national |
This application is a National Stage completion of PCT/EP2018/077734 filed Oct. 11, 2018, which claims priority from German patent application serial no. 10 2017 219 999.7 filed Nov. 10, 2017.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/077734 | 10/11/2018 | WO | 00 |
