Power split gearbox

Abstract

Power-split transmission with an input shaft (3) which can be connected to a drive motor (1), with several planetary stages (P1, P2, P3) arranged coaxially to the input shaft (3) and with clutches (K1, K2, K3, K4) by means of which several driving ranges can be switched and with a clutch for forward travel (KV) and a clutch for reverse travel (KR), wherein the input shaft (3) passes through the power-split transmission and at the end of the input shaft (3), which is opposite the drive motor (1), the input shaft (3) is connected to a gear (4) of a spur gear transmission (5) and a first variator (11) is operatively connected to this spur gear transmission (5) and a second variator (15) is operatively connected to a planetary stage (P1), wherein along the extension of the input shaft (3) the clutch for forward travel (KV) and the clutch for reverse travel (KR) are located between the variators (11,15) and the gear (4) of the spur gear transmission (5), which is connected to the input shaft (3), characterized in that the variators (11, 15) are designed as electrical machines, are arranged parallel to the input shaft (3) and along the extent of the input shaft (3) between the drive machine (1) and the planetary stage (P1), and in that the variators (11, 15) are distributed around the circumference of the planetary stages (P1, P2, P3) and are therefore not arranged coaxially to each other.

Description

[0001] The invention relates to a power split transmission of the type defined in more detail in the preamble of claim 1.

[0002] Power-split transmissions of this type are used particularly in agricultural or municipal vehicles. An example of such an agricultural vehicle is a tractor.

[0003] DE 101 28 076 A1 discloses a power-split transmission in which an input shaft passes through the transmission and drives a variator via a spur gear transmission, and the input shaft is operatively connected to a power take-off, for example, to pumps for the working hydraulics. The drive has several planetary stages and clutches with which driving ranges can be selected, as well as a clutch for forward travel and a clutch for reverse travel with which the direction of travel can be selected. This type of transmission is also referred to as a primary-coupled power-split transmission. DE 10 2005 030 603 A1 relates to a vehicle drive system which has a differential mechanism for providing a differential and transmission function. DE 10 2016 204 727 A1 relates to a continuously variable power-split transmission for a vehicle with an electric variator.US 2011 / 0 031 053 A1 concerns a power-split transmission with a mechanical transmission and a hydraulic transmission.

[0004] The term variator refers to a variator machine in a power-split transmission.

[0005] The present invention is based on the objective of creating a power-split transmission by means of which the working hydraulic pumps and the variators can be driven in a simple manner and the transmission can be modularly constructed with respect to the variators.

[0006] The problem is solved with a generic power-split transmission that also exhibits the characteristic features of the main claim.

[0007] According to the invention, the power-split transmission has an input shaft which can be connected to a drive motor, for example, an internal combustion engine, and which extends through the entire power-split transmission. Several planetary gear stages are arranged coaxially to this input shaft and can be controlled by clutches so that several driving ranges can be selected. The clutches are also arranged coaxially to the input shaft. Furthermore, the power-split transmission has a clutch for forward travel and a clutch for reverse travel, which are arranged downstream of the planetary gear stages. At the end of the input shaft opposite the drive motor, a gear is connected to the drive shaft. A variator and a power take-off, for example for the hydraulic system and / or the steering pumps, are driven via this gear.

[0008] In one embodiment of the invention, the gear connected to the input shaft is operatively connected to a spur gear on a countershaft, the further spur gear of which meshes with the spur gear of the variator's drive shaft. Additionally, this spur gear meshes via an intermediate gear with a spur gear that drives the auxiliary output shaft. This makes it possible to arrange the variators between the drive motor and the planetary gear sets. The variators are designed as electric machines, which, according to this invention, can be housed in a separate gearbox casing. The variators are arranged parallel to the input shaft.

[0009] If the variators are not arranged next to the planetary gear stages, but coaxially to the input shaft, the space next to the planetary gear stages can be used to house the power electronics for the variators, which are designed as electric machines. The power electronics can be located inside the gearbox housing or outside of it and attached to the gearbox housing.

[0010] In a further embodiment of the invention, the two variators are designed as electric machines of nearly identical size, which allows the variator operatively connected to the planetary stage to operate at a lower speed. This makes it possible to use a relatively long shaft, extending over the entire length of the transmission, to drive the variator, which is driven by the input shaft via the spur gear transmission.

[0011] Further characteristics can be found in the character description.

[0012] They show Fig. 1 a non-inventive embodiment of the transmission with variators arranged parallel to the input shaft Fig. 2 a power split transmission with the electric variators between the drive motor and the planetary stages according to an embodiment of the present invention Fig. 3 a power split transmission with the variators in a separate transmission housing according to an embodiment of the present invention and Fig. 4 a power split transmission not according to the invention with a variator between the drive motor and the planetary stages and a variator parallel to the input shaft in the area of ​​the planetary stages. Figure 1:

[0013] A drive motor 1, for example an internal combustion engine or an electric motor, drives an input shaft 3 via a vibration damper 2. The input shaft 3 extends through the entire transmission and drives the gear 4, with which the input shaft 3 is operatively connected. The input shaft 3 can be a single piece or multiple pieces. The gear 4 of the spur gear 5 drives the spur gear 6. The spur gear 6 is connected to the countershaft 7 and drives the spur gear 8. The intermediate gear 12 drives the spur gear 13, which drives the shaft for the power take-off 14. This shaft 14 can drive hydraulic pumps, for example, for the working hydraulics, the steering pump, or the transmission pump. The drive shaft 10, which drives the variator 11, is connected to the spur gear 9. The variator 11 can be an electric motor.However, it is also possible to design the variator 11 as a hydraulic machine. The sun gear 20 of the first planetary stage P1 is operatively connected to the spur gear 17, which meshes with the spur gear 21. The spur gear 21 is connected to the drive shaft 16, which is operatively connected to the variator 15. The variator 15 can be designed as an electric machine. However, it is also possible for the variator 15 to be designed as a hydraulic machine. The planetary stages P1, P2, P3, and P4 can be switched via the clutches K1, K2, K3, and K4, as well as the brake B, so that four driving ranges are selectable. These four driving ranges can be switched between forward and reverse directions via the direction-of-travel clutches KV and KR. The variator 11 and the variator 15 are arranged along the input shaft 3, outside of the planetary stages P1, P2, and P3.Preferably, the variator 11 and the variator 15 are not arranged coaxially to each other, but rather distributed around the circumference of the planetary stages P1, P2, and P3. This makes it possible to design the drive shaft 10 and the drive shaft 16 as a shorter drive shaft. The sun gears of planetary stages P2 and P3 are connected to each other. The ring gear of planetary stage P2 and the planet carrier of planetary stages P1 and P3 are connected to each other. The ring gear of planetary stage P1 is connected to the planet carrier of planetary stage P2.

[0014] The output to the front axle 23 is designed as a spur gear. By arranging the output to the front axle 23 between the output to the rear axle 19 and the gear 4, it is possible to design the gear 4 with a large diameter and to connect the countershaft 7 to the input shaft 3 without an intermediate gear. Figure 2:

[0015] The execution of the Fig. 2 differs from the execution of the Fig. 1 essentially by the fact that the drive shaft 10 is longer and the variator 11 and the variator 15 are arranged between the drive motor 1 and the planetary stage P1 and that the planetary stage P1, P2, P3 of the Fig. 1 were replaced by a stepped planetary gear set, and the coupling K3 now couples the planet carrier of the stepped planetary gear set with the ring gear of the planetary stage P4, and not as in Fig. 1 couples the planet carrier of planetary stage P4. By positioning variator 11 and variator 15 close to input shaft 3, a single spur gear stage is sufficient to drive variator 15. Furthermore, variator 11 and variator 15 can be housed in separate casings. This solution also allows for the creation of a compact, power-split transmission. Planetary stages P1 and P2 share a common planet carrier on which the planetary gears are mounted. The sun gear of planetary stage P1 is connected to input shaft 3. Figure 3:

[0016] The structure essentially corresponds to the structure of the Fig. 2, wherein the variators 11 and 15 are mounted in a separate gearbox housing and the drive shaft 10 is of a multi-section design. If two electric variators 11 and 15 of the same size are used, the speed of variator 11 can be reduced, since the maximum torque required in operation for variator 11 is less than that of variator 15. Figure 4:

[0017] The execution of the Fig. 4 features a variator 15, which is arranged between the drive motor 1 and the planetary stage P1, wherein the variator 11 is arranged outside the planetary stage and is thus located parallel to it in the area of ​​the shift drum 22. The shift drum 22 is symbolically represented for the planetary stages and clutches which the shift drum 22 contains. The working hydraulics are to be as described in the Fig. 1 to 3 must be trained. Reference sign 1 drive motor 2 vibration dampers 3 Input wave 4 gear 5 Spur gear units 6 Spur gear 7 Countershaft 8 Spur gear 9 Spur gear 10 Drive shaft 11 Variator 12 Intermediate wheel 13 Spur gear 14 Shaft for the power take-off 15 variator 16 Drive shaft 17 Spur gear 18 Spur gear 19 Drive to the rear axle 20 sun wheel 21 Spur gear 22 Switching drum 23 Drive to the front axle K1 clutch K2 clutch K3 clutch K4 clutch B brake P1 Planetary Stage P2 Planetary Stage P3 Planetary Stage P4 Planetary Stage KV directional coupling KR Directional Coupling

Claims

[1] Power split transmission with an input shaft (3) which can be connected to a drive motor (1), with several planetary stages (P1, P2, P3) arranged coaxially to the input shaft (3) and with clutches (K1, K2, K3, K4) by means of which several driving ranges can be switched and with a clutch for forward travel (KV) and a clutch for reverse travel (KR), wherein the input shaft (3) passes through the power split transmission and at the end of the input shaft (3), which is opposite the drive motor (1), the input shaft (3) is connected to a gear (4) of a spur gear transmission (5) and a first variator (11) is operatively connected to this spur gear transmission (5) and a second variator (15) is operatively connected to a planetary stage (P1), wherein along the extension of the input shaft (3) the clutch for forward travel (KV) and the clutch for reverse travel (KR) are located between the variators (11,15) and the gear (4) of the spur gear (5), which is connected to the input shaft (3), are arranged, , characterized by , that the variators (11, 15) are designed as electrical machines, arranged parallel to the input shaft (3) and along the extent of the input shaft (3) between the drive machine (1) and the planetary stage (P1), and by the fact that the variators (11, 15) are distributed around the circumference of the planetary stages (P1, P2, P3) and are therefore not coaxial to each other. [2] Power split transmission according to claim 1, characterized by , that the first variator (11) is coupled to the input shaft (3) via a countershaft (7) and four spur gears (4, 8, 6, 9). [3] Power split transmission according to claim 1, characterized by, that the power split transmission has a transmission housing section in which the variators (11, 15) are arranged and a housing section separate from this in which the planetary stages (P1, P2, P3) are arranged. [4] Power split transmission according to claim 1, characterized by , that the variator (11), which is operatively connected to the input shaft (3), has a drive shaft (10) which is connected to the spur gear (9) which is in engagement with the spur gear (8) of a countershaft (7), wherein the countershaft (7) is connected to a further spur gear (6) which meshes with the gear (4) of the spur gear transmission (5) which is connected to the input shaft (3). [5] Power split transmission according to claim 4, characterized by, that an auxiliary output shaft (14) for driving auxiliary consumers is connected to a spur gear (13) which meshes with the spur gear (8) of the countershaft (7) via another spur gear (12). [6] Power split transmission according to claim 5, characterized by , that the spur gear (9) which is connected to the drive shaft of the variator (11) meshes with a spur gear (8) of the countershaft (7), which meshes via the further spur gear (12) with the spur gear (13) of the auxiliary output shaft (14). [7] Power split transmission according to claim 1, characterized by , that the variators (11, 15) are almost the same size. [8] Power split transmission according to claim 2, characterized by , that a spur gear (9) is connected to the first variator (11) in a rotationally fixed manner, two spur gears (8, 6) are connected to the countershaft (7) in a rotationally fixed manner and a spur gear (4) is connected to the input shaft (3) in a rotationally fixed manner.

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