Transaxle for hybrid vehicle

Abstract

To provide a transaxle for a hybrid vehicle that can be easily fabricated into a series-parallel type and a series type by sharing components.SOLUTION: A transaxle 1 includes: an input shaft 2 connected to an engine 8; a first motor 4 generating electricity; a planetary gear set 3 with three rotating elements; and a second motor 5 that outputs a driving torque. The transaxle 1 can configure a series-parallel type hybrid drive device by connecting a ring gear 3a to an output member 6, connecting a sun gear 3b to the first motor 4, and connecting a carrier 3c to the input shaft 2. A series type hybrid drive device is configured by connecting the ring gear 3a to the input shaft 2, connecting the sun gear 3b to the first motor 4, and engaging the carrier 3c with a casing 7 to be fixed so as not to rotate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drive train of a hybrid vehicle equipped with an engine and a motor as power sources, or to a transaxle for a hybrid vehicle constituting a hybrid drive device. [Background technology]

[0002] Patent Document 1 describes an invention related to a transaxle used in a hybrid vehicle. The transaxle described in Patent Document 1 includes two motors, a power split mechanism, a differential gear, and the like inside a casing. Both of the two motors are so-called motor generators that have the functions of both a prime mover and a generator, and are arranged in parallel on different rotation axes. The power split mechanism is composed of a planetary gear set having three rotating elements, a sun gear, a ring gear, and a carrier, and is arranged coaxially with one of the motors and the engine. The transaxle described in Patent Document 1 is connected to an engine to form a series-parallel type (or split type) hybrid drive device.

[0003] Patent Document 2 describes an invention related to a transaxle for a series hybrid vehicle. The transaxle described in Patent Document 2 includes two motors, one for generating electricity and one for driving, a winding transmission mechanism, and a differential gear. The two motors are arranged in parallel on different rotation axes. The winding transmission mechanism is a chain transmission mechanism made up of a sprocket and a chain, and serves as a speed increasing mechanism that increases the rotation speed of the generator motor relative to the rotation speed of the input shaft between the input shaft to which torque is transmitted from the engine and the generator motor. The transaxle described in Patent Document 2 is connected to the engine to form a series type hybrid drive device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-19373 A [Patent Document 2] JP 2019-73213 A Summary of the Invention [Problem to be solved by the invention]

[0005] The series-parallel hybrid vehicle transaxle described in the above Patent Document 1 and the series hybrid vehicle transaxle described in the above Patent Document 2 both have a common configuration incorporating two motors or motor generators. However, there are many other differences between the two, such as the arrangement of the rotating shafts and the components, and for example, it is not easy to share casings, gear sets, etc. between a series-parallel transaxle and a series transaxle.

[0006] This invention was devised with an eye on the technical challenges described above, and aims to provide a transaxle for a hybrid vehicle that can be easily made into either a series-parallel type or a series type by sharing the same casing, gear set, etc. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides an electric vehicle power generating system comprising: an input shaft connected to an engine to receive output torque of the engine; a first motor receiving the output torque and generating electricity; a power split planetary gear set having a first rotating element, a second rotating element, and a third rotating element; a second motor outputting drive torque for a vehicle; and a casing accommodating at least the input shaft, the first motor, the planetary gear set, and the second motor, wherein the input shaft, the first motor, and the planetary gear set are all disposed on a coaxial first shaft, and the second motor is disposed on a second shaft different from the first shaft, and the first rotating element is disposed on a second shaft to which the drive torque is transmitted. a series-parallel type hybrid drive unit configured by connecting the planetary gear set to an output member reaching the input shaft, connecting the second rotating element to the first motor, and connecting the third rotating element to the input shaft, wherein the planetary gear set is configured using helical gears, the first rotating element is connected to the input shaft, the second rotating element is connected to the first motor, and the third rotating element is engaged with the casing and fixed non-rotatably at a location where the thrust force of the helical gear acts on the casing, and is connected to the engine to configure a series type hybrid drive unit.

[0008] In addition, when the series-parallel type hybrid system is configured, the present invention includes a bearing that supports the ring gear of the planetary gear set, and the third rotating element in this invention may be configured to engage with the casing outside the position of the bearing where the thrust force acts, in the direction of action of the thrust force, i.e., at a position farther in the direction of action of the thrust force than the position where the thrust force acts on the bearing.

[0009] In the present invention, the first rotating element may be the ring gear, the second rotating element may be a sun gear, and the third rotating element may be a carrier.

[0010] Alternatively, in the present invention, the first rotating element may be a carrier, the second rotating element may be a sun gear, and the third rotating element may be the ring gear. Effect of the Invention

[0011] The hybrid vehicle transaxle of the present invention includes a first motor that functions mainly as a generator, a second motor that functions mainly as a prime mover, and a planetary gear set having three rotating elements. Therefore, by installing the planetary gear set so that it functions as a power split mechanism, a series-parallel type hybrid drive device can be configured. Furthermore, the hybrid vehicle transaxle of the present invention is configured so that the third rotating element of the planetary gear set can be engaged with the casing to stop rotation. Therefore, by engaging the third rotating element with the casing and installing the planetary gear set so that it functions as a speed change mechanism (specifically, a speed increasing mechanism), and by making the first motor function as a dedicated generator and making the second motor function as a dedicated drive motor, a series-parallel type hybrid vehicle transaxle and a series type hybrid vehicle transaxle can be separately manufactured by sharing the first motor, the second motor, the planetary gear set, and the casing.

[0012] Therefore, according to the hybrid vehicle transaxle of the present invention, it is possible to easily manufacture a series-parallel hybrid vehicle transaxle and a series hybrid vehicle transaxle by sharing the main components, thereby reducing the cost of each type of hybrid vehicle transaxle. [Brief description of the drawings]

[0013] [Figure 1]FIG. 1 is a diagram for explaining the configuration of a transaxle for a hybrid vehicle of the present invention, and is a cross-sectional view showing an example in which a carrier of a planetary gear set is fixed to a casing to configure a series-type transaxle for a hybrid vehicle. [Diagram 2] FIG. 2 is a diagram for explaining the configuration of the transaxle for a hybrid vehicle of the present invention, and is a cross-sectional view showing an example of a structure for engaging and fixing the carrier of the planetary gear set to the casing. [Diagram 3] FIG. 3 is a diagram for explaining the configuration of a transaxle for a hybrid vehicle according to the present invention, and is a skeleton diagram showing an example in which the carrier of the planetary gear set is fixed and the planetary gear set functions as a speed increasing mechanism. [Figure 4] FIG. 4 is a diagram for explaining the configuration of the transaxle for a hybrid vehicle of the present invention, and is a cross-sectional view showing an example of the position where the carrier of the planetary gear set is engaged with and fixed to the casing. [Diagram 5] FIG. 5 is a diagram for explaining the configuration of the transaxle for a hybrid vehicle of the present invention, and is a skeleton diagram showing an example in which a planetary gear set is made to function as a power split mechanism to configure a series-parallel type transaxle for a hybrid vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings. Note that the following embodiment is merely an example of a specific embodiment of the present invention, and is not intended to limit the present invention.

[0015] A hybrid vehicle transaxle in an embodiment of the present invention can be applied to, for example, a series-type hybrid vehicle as shown in Fig. 1. The hybrid vehicle transaxle (hereinafter, transaxle) 1 shown in Fig. 1 includes, as main components, an input shaft 2, a planetary gear set 3, a first motor (MG1) 4, a second motor (MG2) 5, an output member 6, and a casing 7.

[0016] The input shaft 2 is connected to an engine (ENG) 8 combined with the transaxle 1, and receives the output torque of the engine 8. In the example shown in FIG. 1, the input shaft 2 is connected to an output shaft (crankshaft) 8a of the engine 8 via a flywheel 9, a damper device 10, and the like. The input shaft 2 is also connected to a ring gear 3a of a planetary gear set 3, which will be described later, and transmits the output torque of the engine 8 to the ring gear 3a. The input shaft 2 is disposed coaxially with the output shaft 8a of the engine 8. The planetary gear set 3, which will be described later, is disposed coaxially with the input shaft 2.

[0017] The planetary gear set 3 is a differential mechanism having three rotating elements, a ring gear 3a, a sun gear 3b, and a carrier 3c. In the example shown in FIG. 1, a single-pinion type planetary gear set 3 is used. The planetary gear set 3 is arranged coaxially with the input shaft 2 and a first motor 4 described later. In the example shown in FIG. 1, the ring gear 3a is connected to the input shaft 2, the sun gear 3b is connected to a rotor shaft 4a of the first motor 4 described later, and the carrier 3c is engaged with a casing 7 described later and fixed so as not to rotate. Therefore, in the example shown in FIG. 1, the ring gear 3a corresponds to a first rotating element in the embodiment of the present invention, the sun gear 3b corresponds to a second rotating element in the embodiment of the present invention, and the carrier 3c corresponds to a third rotating element in the embodiment of the present invention.

[0018] In an embodiment of the present invention, the planetary gear set 3 may be configured so that the carrier 3c is connected to the input shaft 2 as the first rotating element, the sun gear 3b is connected to the rotor shaft 4a of the first motor 4 described later as the second rotating element, and the ring gear 3a is engaged with the casing 7 described later and fixed so as not to rotate as the third rotating element.

[0019] Each gear of the planetary gear set 3 is made up of a helical gear. Helical gears have the advantage that they mesh more smoothly with each other than spur gears, reducing the impact caused by meshing and suppressing noise and vibration. On the other hand, helical gears generate thrust force in the axial direction. The thrust force of the planetary gear set 3 will be described later.

[0020] As described above, the third rotating element (carrier 3c or ring gear 3a) of the planetary gear set 3 is fixed so as not to rotate, so that the planetary gear set 3 functions as a "speed change mechanism" that increases or decreases the rotation speed of the second rotating element relative to the rotation speed of the first rotating element. In the example shown in FIG. 1, the planetary gear set 3 serves as a "speed increasing mechanism" that increases the rotation speed of the second rotating element, i.e., the first motor 4 connected to the sun gear 3b, relative to the rotation speed of the engine 8 connected to the first rotating element, i.e., the ring gear 3a. For example, if the number of teeth of the ring gear 3a of the planetary gear set 3 is "78" and the number of teeth of the sun gear 3b is "30", the gear ratio therebetween is "0.385", and the ratio between the rotation speed of the engine 8 and the rotation speed of the first motor 4 is "1:2.6". In this case, for example, if the rotation speed of the engine 8 is "5000 rpm", the rotation speed of the first motor 4 driven by the output torque of the engine 8 increases to "13000 rpm". In this way, by configuring the planetary gear set 3 as a "speed increasing mechanism", it is possible to efficiently generate power by driving the first motor 4 with the output torque of the engine 8.

[0021] The first motor 4 is a generator that receives the output torque of the engine 8 and generates electricity. The first motor 4 is arranged coaxially with the input shaft 2 and the planetary gear set 3. That is, as shown in FIG. 1, the input shaft 2, the planetary gear set 3, and the first motor 4 are all arranged on a first axis AX1 that is coaxial with the output shaft 8a of the engine 8. In the example shown in FIG. 1, the rotor shaft 4a of the first motor 4 is connected to the sun gear 3b of the planetary gear set 3. Therefore, the output torque of the engine 8 is transmitted to the first motor 4 via the planetary gear set 3. The first motor 4 is driven by the output torque of the engine 8 and generates electricity as a generator.

[0022] The second motor 5 is driven by the supply of electric power and functions as a prime mover that outputs a driving torque. The second motor 5 is connected to an output member 6, which will be described later. Therefore, the driving torque output by the second motor 5 is transmitted to the output member 6. As shown in FIG. 2, the second motor 5 is disposed on a second axis AX2 that is different from the above-mentioned first axis AX1 and is parallel to the first axis AX1.

[0023] The output member 6 is a rotating member to which the driving torque output by the second motor 5 is transmitted. For example, it is constituted by a driven gear of a gear transmission mechanism or a driven sprocket of a chain transmission mechanism. In the example shown in FIG. 1, a "counter gear" that meshes with a pinion 5b attached to the tip of a rotor shaft 5a of the second motor 5 corresponds to the output member 6 in the embodiment of the present invention. As will be described later, the output member 6 is connected to a third rotating element (carrier 3c or ring gear 3a) of the planetary gear set 3 when the planetary gear set 3 functions as a "power split mechanism" and a series-parallel type hybrid drive unit is configured with the transaxle 1. The "counter gear" is connected to a drive shaft (not shown) so as to be capable of transmitting power, for example, via a reduction gear (not shown) and a differential gear (not shown).

[0024] The casing 7 forms the outer shell of the transaxle 1 and houses at least the input shaft 2, planetary gear set 3, first motor 4, second motor 5, and output member 6. In the example shown in Fig. 1, the casing 7 is made up of a housing 7a having a mounting surface 8b for the engine 8, a case 7b that is assembled with the housing 7a and forms a central portion of the outer shell of the transaxle 1 in the axial direction, and a rear cover 7c that is assembled to the rear end (the end on the left side in Fig. 1) of the case 7b and forms the rear end portion of the outer shell of the transaxle 1 in the axial direction.

[0025] As described above, the casing 7 engages with the third rotating element of the planetary gear set 3 to fix the third rotating element in an unrotatable manner. In the example shown in FIG. 1, the casing 7 engages with the carrier 3c of the planetary gear set 3 to fix the carrier 3c in an unrotatable manner. For example, as shown in FIG. 2, a protrusion 3d is formed on the outer circumferential portion of the carrier 3c, which protrudes the outer circumferential surface of the carrier 3c in a radially outwardly convex shape. Then, a recess (not shown) is formed on the inner circumferential portion of the casing 7, which is recessed in a concave shape with which the protrusion 3d can be engaged, in correspondence with the shape of the protrusion 3d. Therefore, in the transaxle 1 according to the embodiment of the present invention, when the planetary gear set 3 is assembled inside the casing 7, the protrusion 3d formed on the carrier 3c is engaged with the recess formed on the casing 7, and the recess of the casing 7 acts as a rotation stopper, so that the carrier 3c can be easily fixed in an unrotatable state.

[0026] As described above, the position (engagement portion 11) where the protrusion 3d of the carrier 3c is engaged inside the casing 7 is determined in consideration of the thrust force generated by the helical gear of the planetary gear set 3. As described above, each gear of the planetary gear set 3 is configured using a helical gear. Therefore, when the planetary gear set 3 rotates under load, a thrust force is generated in each gear constituting the planetary gear set 3, that is, the ring gear 3a, the sun gear 3b, and the pinion (planetary gear) 3e, as shown by arrows in the skeleton diagram of FIG. 3. A thrust force acts on the carrier 3c holding the pinion 3e of the planetary gear set 3 in the axial direction of the first shaft AX1, in the direction from the engine 8 to the first motor 4 (leftward in FIG. 3). Therefore, in the transaxle 1 according to the embodiment of the present invention, the engagement portion 11 is provided on the side where the casing 7 receives the thrust force acting on the carrier 3c.

[0027] More specifically, as shown in FIG. 4, the transaxle 1 includes bearings 12 and 13 that support the ring gear 3a of the planetary gear set 3. Both of the bearings 12 and 13 support the inner circumferential portion of the cylindrical ring gear 3a on the casing 7. In the example shown in FIG. 4, the bearing 12 supports the end of the ring gear 3a on the engine 8 side (right side in FIG. 4) in the axial direction, and the bearing 13 supports the end of the ring gear 3a on the first motor 4 side (left side in FIG. 4) in the axial direction. The carrier 3c of the planetary gear set 3 is configured to engage with the casing 7 on the outer side of the position of the bearing 13 on which the thrust force acts in the acting direction of the thrust force on the carrier 3c. In other words, the carrier 3c is configured to engage with the casing 7 at a position farther away from the position of the bearing 13 on which the thrust force acts in the acting direction of the thrust force than the position on which the thrust force acts. That is, the engagement portion 11 that engages the protrusion 3d of the carrier 3c with the recess of the casing 7 is provided on the casing 7 located outside the arrangement position of the bearing 13 on which the thrust force acts in the acting direction of the carrier 3c. In the example shown in Fig. 4, the engagement portion 11 is formed on the case 7b, which is located outside the arrangement position of the bearing 13, among the three members (housing 7a, case 7b, rear cover 7c) that constitute the casing 7.

[0028] 3, a thrust force acts on the ring gear 3a of the planetary gear set 3 in the opposite direction to the thrust force acting on the carrier 3c. Therefore, for example, when the ring gear 3a is engaged with the casing 7 as the third rotating element of the planetary gear set 3 and fixed so as not to rotate, and the planetary gear set 3 constitutes a "speed increasing mechanism," an engagement portion 11 is formed on the housing 7a located outside the position of the bearing 12 on which the thrust force of the ring gear 3a acts.

[0029] In this way, in the transaxle 1 according to the embodiment of the present invention, the above-mentioned anti-rotation device, i.e., the engagement portion 11, is provided at a portion that receives the thrust force acting on the third rotating element of the planetary gear set 3 (the carrier 3c in the example shown in FIGS. 1 and 3) when the engine 8 is operating under load and the first motor 4 generates electricity. Therefore, the thrust force can be received directly at a portion of the casing 7 where strength and rigidity can be easily ensured. In other words, the thrust force can be received at an appropriate portion that is advantageous in terms of strength. Then, by making the planetary gear set 3 function as a "speed increasing mechanism" in the appropriate state as described above, a series type hybrid drive unit can be configured together with the engine 8 assembled to the transaxle 1.

[0030] Furthermore, the transaxle 1 in the embodiment of the present invention can be used to create either a "series type hybrid vehicle transaxle" as described above or a "series-parallel type (or split type) hybrid vehicle transaxle" by sharing the casing 7 and planetary gear set 3.

[0031] FIG. 5 shows an example of a series-parallel hybrid drive device configured with a transaxle 1 according to an embodiment of the present invention. The transaxle 1 shown in the skeleton diagram of FIG. 5 has the same configuration as the "transaxle" used in the "series-parallel hybrid vehicle" described in the above-mentioned Patent Document 1. The transaxle 1 shown in FIG. 5 differs from the series-type hybrid vehicle transaxle 1 shown in FIGS. 1 to 4 only in the connection relationship of each rotating element of the planetary gear set 3. Specifically, in the transaxle 1 shown in FIG. 5, the ring gear 3a of the planetary gear set 3 is rotatably supported by the casing 7 and is connected to the output member 6 so as to be capable of transmitting power. The sun gear 3b is connected to the rotor shaft 4a of the first motor 4. The carrier 3c is connected to the input shaft 2. By connecting each rotating element of the planetary gear set 3 in this manner, the planetary gear set 3 can function as a so-called "power split mechanism" as described in the above-mentioned Patent Document 1. In other words, a series-parallel type hybrid drive unit can be configured with the transaxle 1 configured as shown in FIG.

[0032] As described above, the transaxle 1 for configuring a series type hybrid drive unit and the transaxle 1 for configuring a series-parallel type hybrid drive unit have the same basic configuration of the planetary gear set 3 and the basic configuration of the casing 7. Therefore, with only minor or simple changes in shape and assembly, the series type hybrid vehicle transaxle 1 and the series-parallel type hybrid vehicle transaxle 1 can be configured by sharing the planetary gear set 3 and the casing 7 (as well as other members such as the first motor 4 and the second motor 5). In other words, the series type hybrid vehicle transaxle 1 and the series-parallel type hybrid vehicle transaxle 1 can be easily manufactured separately.

[0033] Therefore, according to the hybrid vehicle transaxle of the present invention, it is possible to easily manufacture a series-parallel type hybrid vehicle transaxle 1 and a series type hybrid vehicle transaxle 1 separately by sharing the main components, thereby reducing the cost of the hybrid vehicle transaxle 1 of each type. [Explanation of symbols]

[0034] 1 Transaxle (transaxle for hybrid vehicles) 2 Input Shaft 3 Planetary Gear Set 3a Ring gear (first rotating element or third rotating element) 3b Sun gear (second rotating element) 3c Carrier (third rotating element or first rotating element) 3d Protrusion (planetary gear) 3e Pinion (planetary gear) 4. First motor (MG1) 4a (First motor) rotor shaft 5 Second motor (MG2) 5a (Second motor) rotor shaft 6 Output member 7 Casing 7a Housing 7b Case 7c Rear cover 8 Engine (ENG) 8a (engine) output shaft (crankshaft) 8b (Engine) mounting surface 9 Flywheel 10 Damper device 11 Engagement part 12,13 Bearings AX1 1st axis AX2 2nd axis

Claims

[Claim 1] a transaxle for a hybrid vehicle comprising: an input shaft to which an output torque of an engine is input, a first motor that receives the output torque and generates electricity, a planetary gear set having a first rotating element, a second rotating element, and a third rotating element, a second motor that outputs a drive torque, and a casing that accommodates at least the input shaft, the first motor, the planetary gear set, and the second motor, wherein the input shaft, the first motor, and the planetary gear set are all disposed on a coaxial first shaft, and the second motor is disposed on a second shaft different from the first shaft, and the first rotating element is connected to an output member to which the drive torque is transmitted, the second rotating element is connected to the first motor, and the third rotating element is connected to the input shaft, thereby forming a series-parallel type hybrid drive unit, The planetary gear set is configured using helical gears, The first rotating element is coupled to the input shaft, the second rotating element is coupled to the first motor; the third rotating element is engaged with the casing at a location where a thrust force of the helical gear acts on the casing and is fixed so as not to rotate, A series hybrid drive system is formed by connecting the engine to the vehicle. A transaxle for a hybrid vehicle.

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