Electrically adjustable gearbox with an offset motor / generator

Abstract

Electrically adjustable transmission (34) for a hybrid vehicle (30), comprising: a transmission input shaft (38) defining a first axis of rotation (40); a transmission output shaft (42) coupled to the transmission input shaft (38), the transmission output shaft (42) defining a second axis of rotation (44); a first motor / generator (48) functionally connected to the transmission input shaft (38), the first motor / generator (48) being configured to rotate about a third axis of rotation (54) spaced apart from the first axis of rotation (40);and a second motor / generator (50) functionally connected to the transmission input shaft (38), wherein the second motor / generator (50) is arranged to rotate about the first axis of rotation (40), a first planetary gear set (82), a second planetary gear set (84) and three clutches (C1, C2, C3), wherein the first planetary gear set (82) comprises a ring gear (R1), a planet carrier (PC1) and a sun gear (S1), and the second planetary gear set (84) comprises a ring gear (R2), a planet carrier (PC2) and a sun gear (S2); wherein the transmission (34) is functionally connected to a machine (32);characterized in that the transmission (34) is functionally connected to the machine (32) via a damper (80), a chain (70) permanently connects the first motor / generator (48) to the ring gear (R1) and the sun gear (S2), wherein the engagement of the third clutch (C3) fixes the first motor / generator (48) to ground such that the first motor / generator (48) is held stationary, the second motor / generator (50) is permanently connected to the sun gear (S1), wherein the engagement of the second clutch (C2) connects the second motor / generator (50) to the ring gear (R2), and the engagement of both the first and the second clutches (C1, C2) fixes the second motor / generator (50) to ground such that the second motor / generator (50) is held stationary, and that the output power from the planet carrier (PC2) to the second axis of rotation (44) is transmitted via a Chain (46) is transmitted to drive wheels (36).

Description

The present invention relates generally to an electrically variable transmission having an off-axis motor / generator.A conventional electrically variable transmission (EVT) includes two electric motors, such as electric motor / generators, disposed on the transmission drive axle. The location of the two electric motors on the transmission drive axle limits flexibility in design for accommodating such motors, particularly in front wheel drive applications.U.S. Pat. No. 6,557,656 B2 discloses electrically variable transmissions having two motor / generators, wherein the two motor / generators in the different embodiments disclosed therein are either both arranged offset axially with respect to the transmission drive shaft or are both arranged coaxially with respect to the transmission drive shaft.JP 2005-1 564 A discloses an electrically variable transmission according to the preamble of claim 1.It is the object of the invention to provide an electrically variable transmission with two motor / generators with an improved design.This object is achieved by a transmission having the features of claim 1.The invention is described below by way of example with reference to the drawings: FIG. 1 is a schematic illustration of a conventional hybrid vehicle transmission; FIG. 2 is a schematic illustration of a hybrid vehicle according to the preferred embodiment of the present invention; FIG. 3 is a stick diagram illustrating the electrically variable transmission of FIG. 2 in more detail.Referring now to FIG. 1, there is shown a schematic illustration of a conventional hybrid vehicle transmission 10. The transmission 10 includes an input shaft 12 defining a drive axis or first axis 14 and an output shaft 16 defining an output axis or second axis 18. The transmission 10 also includes a first motor / generator 20 and a second motor / generator 22, respectively. the first and second motor / generators 20 and 22 each include a drive / output shaft 24, 26 configured to rotate about the transmission drive axis 14. The first and second motor / generators 20, 22 are referred to as "on-axis" motor / generators because their input / output shafts 24, 26 each define an axis of rotation that coincides with the transmission input axis 14. Conventional hybrid vehicle transmissions having multiple on-axis motor / generators generally have a limited available space along the transmission drive axis 14.Referring now to FIG. 2, there is shown a schematic illustration of a hybrid vehicle 30 in accordance with the present invention. The hybrid vehicle 30 includes an engine 32, a transmission 34, and a plurality of wheels 36. The input shaft 38 defines a drive axis or first axle 40 for the transmission 34. the transmission 34 transmits output power to the wheels 36 via an output shaft 42. the output shaft 42 defines an output axis or second axle 44 for the transmission 34.The transmission 34 includes a first motor / generator 48 and a second motor / generator 50. the first motor / generator 48 includes a drive / output shaft 52 that rotates about a third axis 54, and the second motor / generator 50 preferably includes a drive / output shaft 56 that rotates about the first axis 40. A sprocket 60 is connected to the input / output shaft 52 of the first motor / generator 48The first motor / generator 48 is an "off-axis" motor / generator because its input / output shaft 52 defines an axis of rotation that is different from the transmission input axis 40. the second motor / generator 50 is an "on-axis" motor / generator because its input / output shaft 56 defines an axis of rotation that matches the transmission input axis 40. The off-axis motor / generator 48 and the on-axis motor / generator 50 together require less space along the transmission drive axis 40 than conventional designs that include two on-axis motor / generators. Thus, the transmission 34 is easier to accommodate in hybrid vehicle applications that have a limited available space along the transmission drive axis 40, such as in front wheel drive applications.Referring now to FIG. 3, an embroidery diagram shows the transmission 34 of FIG. 2 in more detail. In FIG. 3, like reference numerals are used to refer to like components as in FIG. 2.The transmission 34 is shown operatively connected to the engine 32 via a damper 80. The transmission 34 includes a first planetary gear set 82, a second planetary gear set 84, and three clutches C 1-C 3. The first planetary gear set 82 includes a ring gear R 1, a planet carrier PC 1, and a sun gear S 1. The second planetary gear set 84 includes a ring gear R 2, a planet carrier PC 2, and a sun gear S 2. A plurality of bushings or bearings 86 are used to facilitate relative rotation between transmission components.The first motor / generator 48 is configured to rotate about the third axis 54. The chain 70 permanently connects the first motor / generator 48 to the ring gear R 1 and the sun gear S 2. The engagement of the third clutch C 3 ground-locks the first motor / generator 48 such that the first motor / generator 48 is locked or held stationary. The second motor / generator 50 is configured to rotate about the first axis 40. The second motor / generator 50 is permanently connected to the sun gear S 1. Engagement of the second clutch C 2 connects the second motor / generator 50 to the ring gear R 2, and engagement of both the first and second clutches C 1, C 2 ground the second motor / generator 50 such that the second motor / generator 50 is locked or held stationary. The output from the planet carrier PC2 is transmitted to the second rotary shaft 44 via the chain 46 to drive the wheels 36 (shown in FIG. 2).

Claims

An electrically variable transmission (34) for a hybrid vehicle (30), comprising: a transmission drive shaft (38) defining a first axis of rotation (40); a transmission output shaft (42) coupled to the transmission drive shaft (38), the transmission output shaft (42) defining a second axis of rotation (44); a first motor / generator (48) operatively connected to the transmission drive shaft (38), the first motor / generator (48) configured to rotate about a third axis of rotation (54) spaced from the first axis of rotation (40); and a second motor / generator (50) operatively connected to the transmission input shaft (38), the second motor / generator (50) configured to rotate about the first axis of rotation (40), a first planetary gear set (82), a second planetary gear set (84), and three clutches (C1, C2, C3), the first planetary gear set (82) including a ring gear (R1), a planet carrier (PC1), and a sun gear (S1), the second planetary gear set (84) including a ring gear (R2), a planet carrier (PC2), and a sun gear (S2); the transmission (34) operatively connected to an engine (32); characterized in that the transmission (34) is operatively connected to the engine (32) via a damper (80), a chain (70) permanently connecting the first motor / generator (48) to the ring gear (R1) and the sun gear (S2), wherein engagement of the third clutch (C3) grounded the first motor / generator (48) such that the first motor / generator (48) is held stationary, the second motor / generator (50) permanently connected to the sun gear (S1), wherein engagement of the second clutch (C2) connects the second motor / generator (50) to the ring gear (R2), and engagement of both the first and second clutches (C1, C2) grounded the second motor / generator (50) such that the second motor / generator (50) is held stationary, and that the output from the planet carrier (PC2) is transmitted to the second rotation axis (44) via a chain (46) to drive wheels (36).

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