Automotive drive device

Abstract

This automotive drive device comprises an input shaft (10), an output shaft (12), a planetary gear (30) comprising a sun gear (32), a ring gear (34), and a carrier (38), a first motor generator (MG) (20), a second MG (22), and a first transmission mechanism (3) and a second transmission mechanism (4) having at least two transmission ratios, namely low and high, wherein: the input shaft (10) is connected to the carrier (38); the first MG (20) is connected to the sun gear (32); the ring gear (34) can be connected to the output shaft (12) via the first transmission mechanism (3); the second MG (22) can be connected to the output shaft (12) via the second transmission mechanism (4); and the configuration is such that when one of the first transmission mechanism (3) and the second transmission mechanism (4) is transmitting power, the transmission ratio of the other can be switched.

Description

Drive device for vehicle

[0001] The present invention relates to a drive device for a vehicle, and more particularly to a drive device for a so-called hybrid vehicle (HV) that includes an engine (internal combustion engine) and a motor generator (hereinafter referred to as "MG") as power sources.

[0002] Conventionally, as a drive device for this type of vehicle, there is provided a planetary gear (differential device) having three rotating elements for dividing an input torque, two MGs respectively connected to two of these rotating elements, and an internal combustion engine connected to the remaining one rotating element. A configuration is known in which an electric continuously variable transmission (hereinafter referred to as "CVT") is formed using a differential device and two MGs and a four-speed automatic transmission having a plurality of engaging devices is combined in series (for example, Patent Document 1).

[0003] Japanese Patent No. 5876442

[0004] In the conventional drive device for a vehicle described in Patent Document 1, a differential unit having a function as a CVT, which is a set of a differential device and two MGs, and a transmission unit having a plurality of engaging devices and capable of four-speed shifting are connected in series. As a result, continuously variable transmission is possible as a whole, and a large driving torque can be obtained when the transmission unit is set to a low speed stage. However, with such a configuration, the axial length of the entire drive device tends to be long, and there is a problem in terms of mounting on a vehicle. In particular, it was very difficult to mount on a vehicle with limited space, such as a front-wheel drive vehicle with a transverse engine. In addition, in the conventional drive device for a vehicle, a shift shock is likely to occur due to the switching of friction elements during shifting, and it was difficult to easily perform smooth shifting.

[0005] Therefore, an object of the present invention is to provide a drive device for a vehicle with improved mounting performance on a vehicle.

[0006] Another object of the present invention is to provide a drive device for a vehicle that can suppress the occurrence of shock during shifting with a simple configuration.

[0007] The automotive drive system of the present invention comprises an input shaft capable of receiving power from an engine, an output shaft arranged parallel to the input shaft, a planetary gear and a first motor-generator consisting of three rotating elements: a sun gear, a ring gear, and a carrier, arranged on the same axis as the input shaft, a second motor-generator arranged parallel to the input shaft, and a first and second transmission mechanism, each having at least two gear ratios of low and high. The input shaft is connected to the carrier, the first motor-generator is connected to the sun gear, the ring gear can be connected to the output shaft via the first transmission mechanism, and the second motor-generator can be connected to the output shaft via the second transmission mechanism. The system is configured such that when one of the first and second transmission mechanisms is transmitting power, the other can switch the gear ratio. This configuration of the present invention is implemented in embodiments 1 to 3 described later.

[0008] It is preferable that the ring gear has a ring gear shaft integrally provided with the ring gear and a motor input shaft connected to a second motor generator, with a first speed change mechanism positioned between the ring gear shaft and the output shaft, and a second speed change mechanism positioned between the motor input shaft and the output shaft. This configuration of the present invention is implemented in embodiments 1 to 3 described later.

[0009] In this case, the ring gear shaft and the motor input shaft are positioned on either side of the output shaft, and it is more preferable that the ring gear shaft and the motor input shaft can be connected via the first and second speed shifting mechanisms. This configuration of the present invention is implemented in embodiments 1 to 3 described later.

[0010] Preferably, the ring gear shaft is selectively connectable to a first gear and a second gear arranged coaxially, the motor input shaft is integrally provided with a third gear and a fourth gear, and the output shaft rotatably supports a fifth gear meshing with the first gear and the third gear, and a sixth gear meshing with the fourth gear, and is selectively connectable to the fifth gear and the sixth gear, and integrally provides a seventh gear meshing with the second gear. This configuration of the present invention is implemented in embodiments 1 and 3 described later.

[0011] In this case, it is more preferable that the input shaft and the output shaft be connected by at least one gear ratio. This configuration of the present invention is implemented in Embodiment 3, which will be described later.

[0012] The ring gear shaft is integrally provided with the coaxial first and second gears, the motor input shaft is selectively connectable to the coaxial third and fourth gears, and the output shaft rotatably supports the fifth gear meshing with the first and third gears and the sixth gear meshing with the second gear, and is selectively connectable to the fifth and sixth gears, and preferably integrally provides a seventh gear meshing with the fourth gear. This configuration of the present invention is implemented in Embodiment 2 described later.

[0013] It is also preferable that the output shaft and the sixth gear be connected by a one-way clutch (OWC). This configuration of the present invention is implemented in embodiments 1 to 3 described later.

[0014] The automotive drive system of the present invention has an output shaft arranged parallel to the input shaft, and a second motor-generator arranged parallel to the input shaft. This reduces the axial length of the drive system, improving its mountability and making it easier to install in vehicles with limited space, such as front-wheel-drive vehicles with a transversely mounted engine. Furthermore, since the system is configured so that the other transmission mechanism switches the gear ratio while one of the first and second transmission mechanisms is transmitting power, a simple configuration can be used to suppress shocks during gear changes and ensure smooth gear changes.

[0015] This is a skeleton diagram showing the main parts of an automobile drive system according to Embodiment 1 of the present invention. This is a diagram showing the arrangement of each axis of Embodiment 1. This is a diagram showing the operation table of Embodiment 1. This is a diagram showing the torque flow in each drive mode of Embodiment 1. This is a diagram showing the torque flow in each drive mode of Embodiment 1. This is a skeleton diagram showing the main parts of an automobile drive system according to Embodiment 2 of the present invention. This is a diagram showing the operation table of Embodiment 2. This is a skeleton diagram showing the main parts of an automobile drive system according to Embodiment 3 of the present invention. This is a diagram showing the operation table of Embodiment 3.

[0016] Hereinafter, an automobile drive system according to an embodiment of the present invention will be described with reference to the figures.

[0017] (Embodiment 1) Figure 1 is a skeleton diagram of the main part of an automobile drive system according to Embodiment 1 of the present invention. The automobile drive system of Embodiment 1 has five shafts, including the MG, arranged as shown in Figure 2 when viewed from the left side of Figure 1. In Figure 2, the reference numeral of the shaft is written at the center of the shaft, and the outer diameter of the largest gear for each shaft is drawn with a thin line. Each shaft is parallel to the input shaft 10, and the first motor-generator 20, output shaft 12, motor input shaft 14, idler gear 22b, and second motor-generator 22 are arranged therein. Furthermore, the cross-section is drawn by unfolding from the bottom of Figure 1 in the order A to E indicated in Figure 2. The circles in Figure 1 illustrate the arrangement of bearings, although a detailed explanation is omitted.

[0018] The input shaft 10 is connected to the crankshaft 1a of the power source engine (indicated as "ICE" in the figure) 1 via a damper 1b, and is connected to the planetary gear 30 and the first motor generator (first MG, indicated as "MG1" in the figure) 20, which are located on the opposite axial side of the engine 1, as follows: The planetary gear 30 is generally called a single-pinion type and has three rotating elements: a sun gear 32, a ring gear 34, and a carrier 38. The sun gear 32 is connected to the first MG 20, the carrier 38 is connected to the input shaft 10, and the ring gear 34 can be connected to the output shaft 12 via the first transmission mechanism 3.

[0019] To describe the first gear shifting mechanism 3 in detail, the ring gear shaft 34a, which is integrally connected to the ring gear 34, can selectively connect to the first gear 34b and the second gear 34c, which are arranged coaxially with it, by shifting them in the axial direction of the first sleeve 34d. The first gear 34b and the second gear 34c mesh with the fifth gear 12f and the seventh gear 12h, respectively, on the output shaft 12, which will be described later, and these constitute the first gear shifting mechanism 3 of the present invention. The gear ratio obtained by this will be described later. Note that the parking gear 34h, which is integrally provided with the second gear 34c, is well known, so its explanation will be omitted.

[0020] Here, the configuration and operation common to the second sleeve 12d of Embodiments 1 and 2 and the third sleeve 10b of Embodiment 3, which will be described later, will be explained using the first sleeve 34d as an example. The first sleeve 34d is positioned radially outward of the first hub 34e, which is integrally provided with the ring gear shaft 34a, and rotates integrally with the first hub 34e and is axially shiftable. The dog teeth 34f and 34g formed on the faces of the first gear 34b and the second gear 34c facing the first sleeve 34d, respectively, will selectively engage with the first sleeve 34d when the first sleeve 34d shifts. Figure 1 shows the neutral state in which the first sleeve 34d is not engaged with either the dog teeth 34f or the dog teeth 34g. Furthermore, engagement between the first sleeve 34d and the dog teeth 34f and 34g is performed by controlling the rotational speed difference between them to be close to zero, and conversely, disengagement is performed by controlling the transmitted torque between them to be close to zero.

[0021] As described above, the shifting of the first sleeve 34d left and right in Figure 1 is performed by a shift fork and actuator (not shown), but since these configurations are well known, their illustration and explanation are omitted. In addition, the notation and explanation of reference numerals such as hub and dog teeth are omitted for the second sleeve 12d in Embodiments 1 and 2 and the third sleeve 10b in Embodiment 3, which will be described later.

[0022] To describe the second gear shift mechanism 4 in detail, the motor input shaft 14 has a third gear 14a integrally provided with it, which is connected to the second motor generator (second MG, described as "MG2" in the figure) 22 via a pinion 22a and an idler gear 22b. The motor input shaft 14 integrally has a fourth gear 14b together with the third gear 14a. The third gear 14a and the fourth gear 14b mesh with the fifth gear 12f and the sixth gear 12g on the output shaft 12, respectively, and these constitute the second gear shift mechanism 4 of the present invention. The gear ratio obtained by this will be described later.

[0023] Here, the relationship between the first gear shifting mechanism 3 and the second gear shifting mechanism 4 and the output shaft 12 will be described in detail. The output shaft 12 integrally has an output gear 12a, which drives the wheels of the automobile via a mating gear (not shown). The output shaft 12 also rotatably supports the aforementioned fifth gear 12f and sixth gear 12g, and by shifting the second sleeve 12d on the output shaft 12 in the axial direction, the output shaft 12 can be selectively connected to either the fifth gear 12f or the sixth gear 12g. That is, when the second sleeve 12d is shifted to the left, the motor input shaft 14 and the output shaft 12 are connected with the third gear 14a and the fifth gear 12f at a high gear ratio. When the second sleeve 12d is shifted to the right, the motor input shaft 14 and the output shaft 12 are connected with the fourth gear 14b and the sixth gear 12g at a low gear ratio. Therefore, the second transmission mechanism 4 has low and high gear ratios. On the other hand, when the first sleeve 34d is shifted to the left in the figure to connect the first gear 34b and the ring gear shaft 34a, the ring gear shaft 34a and the motor drive shaft 14 are connected via the fifth gear 12f meshing with the first gear 34b and the third gear 14a meshing with this fifth gear 12f. In this way, the output shaft 12 and each gear on its coaxial axis are configured to have overlapping functions in the first transmission mechanism 3 and the second transmission mechanism 4.

[0024] Therefore, when the second sleeve 12d is shifted to the left, and the first sleeve 34d is shifted to the left, the ring gear shaft 34a and the output shaft 12 are connected at a high gear ratio. In other words, when the first sleeve 34d and the second sleeve 12d are shifted to the left, both the first transmission mechanism 3 and the second transmission mechanism 4 are connected at a high gear ratio. Also, when the first sleeve 34d in the first transmission mechanism 3 is shifted to the left, and the second sleeve 12d in the second transmission mechanism 4 is shifted to the right, connecting the output shaft 12 and the sixth gear 12g, the ring gear shaft 34a and the output shaft 12 are connected at a low gear ratio via the motor input shaft 14. In other words, when the first sleeve 34d is shifted to the left and the second sleeve 12d is shifted to the right, both the first transmission mechanism 3 and the second transmission mechanism 4 are connected at a low gear ratio. Furthermore, the output shaft 12 has the aforementioned seventh gear 12h integrated into it, and when the first sleeve 34d is shifted to the right, the second gear 34c and the seventh gear 12h connect the ring gear shaft 34a and the output shaft 12 at a middle gear ratio. Thus, the first transmission mechanism 3 has three gear ratios between the ring gear 34 and the output shaft 12: low, middle, and high.

[0025] Furthermore, a one-way clutch (hereinafter referred to as "OWC") 12j connects the seventh gear 12h and the sixth gear 12g. The OWC 12j has the function of transmitting torque in the direction that moves the vehicle forward from the sixth gear 12g to the output shaft 12, and can rotate freely in the reverse direction. In other words, the sixth gear 12g engages with the output shaft 12 via the OWC 12j in the direction that moves the vehicle forward, even without engagement with the second sleeve 12d. Since these are well known, a detailed explanation will be omitted.

[0026] Here, we will explain how to switch between the gear ratios. As mentioned above, the first transmission mechanism 3 has three gear ratios, low, middle, and high, between the ring gear 34 and the output shaft 12. Of these, only the middle gear ratio is obtained independently by the first transmission mechanism 3, and when power is being transmitted in this middle gear ratio, the gear ratio of the second transmission mechanism 4 can be switched as described later. Also, as mentioned above, the second transmission mechanism 4 obtains low and high gear ratios between the motor input shaft 14 and the output shaft 12. Both of these are gear ratios obtained independently by the second transmission mechanism 4, and when power is being transmitted in either the low or high gear ratio, the gear ratio of the first transmission mechanism 3 can be switched as described later.

[0027] Next, the operation of the automotive drive system shown in Figure 1 will be explained in accordance with the operation table shown in Figure 3 and the torque flow diagrams in Figures 4 and 5. In the torque flow diagrams in Figures 4 and 5, the skeleton other than the sleeves shown in Figure 1 is drawn with thin lines, the sleeves and torque flow are drawn with thick lines, and the current is drawn with dashed lines. The sleeves are drawn in a shifted state according to the operation table described later. In the operation table in Figure 3, each drive mode described later is assigned to the vertical direction, and the operating status of the two sleeves, OWC12j and the two MGs, the gear ratio and the mechanical point (M-point) described later are assigned to the horizontal direction. Specifically, the first sleeve 34d is S1, the second sleeve 12d is S2, OWC12j is OWC, the first MG20 is MG1, and the second MG22 is MG2. The arrows in the table for each sleeve represent the shift direction of each sleeve in Figure 1. Note that arrows in parentheses indicate that even if shifted, they are not involved in power transmission. The # mark in the OWC column indicates that engagement of OWC12j is possible. In the case of MG, power generation is represented by G and drive by D. The value of the ICE gear ratio is (rotational speed of ring gear 34) / (rotational speed of output shaft 12), M-point is the gear ratio of the mechanical point, and the value of the MG2 gear ratio is (rotational speed of motor input shaft 14) / (rotational speed of output shaft 12).

[0028] Although not shown in the diagram, the automotive drive system shown in Figure 1 is equipped with, in addition to the aforementioned shift fork and actuator, a battery, various sensors including accelerator pedal depression amount, a controller, an inverter, a shift lever, etc., as needed, and the following operations are basically performed based on the instructions of the controller.

[0029] The drive system shown in Figure 1 has two drive modes: "EV mode" where engine 1 is stopped, and "HV mode" where engine 1 is running. In EV mode, the vehicle is driven as an EV (electric vehicle) by the second MG22, and in HV mode, it is driven as an electric CVT, which will be described later.

[0030] First, let's explain the EV mode, which uses electricity stored in the battery as the power source. In EV mode, power is supplied from the battery to the second MG22 to drive the wheels, and a regenerative braking operation is performed in which the second MG22 is driven from the wheel side during braking to generate electricity and charge the battery. As mentioned above, the second transmission mechanism 4 allows the second MG22 and the output shaft 12 to be driven with two gear ratios, and the low gear ratio E-L is selected for starting and low-speed driving, while the high gear ratio E-H is selected for high-speed driving.

[0031] Switching between E-L and E-H is done by setting the torque of the second MG22 to 0. However, to avoid the drive torque or braking torque of the output shaft 12 becoming temporarily 0, it is desirable to first switch to the HV mode described later and then switch between the low and high gear ratios while driving in HV mode. Note that in EV mode, reverse is the same E-L in the operation table, but the rotation direction of the second MG22 is the opposite of that in forward.

[0032] Next, regarding the electric CVT in HV mode, its operation is well known, but I will explain its overview. The carrier 38, driven from the input shaft 10 by the power of the engine 1, transmits its torque to the sun gear 32 and the ring gear 34. Here, if the tooth ratio of the planetary gear 30 (number of teeth of the sun gear 32 / number of teeth of the ring gear 34) is ρ, then a torque of 1 / (1+ρ) is transmitted to the ring gear 34, and a torque of ρ / (1+ρ) is transmitted to the sun gear 32. If ρ is 0.4 and the torque of the input shaft 10 is 1, then a torque of 0.714 is distributed to the ring gear 34 and a torque of 0.286 is distributed to the sun gear 32. The torque acting on the ring gear 34 is then applied to the low, middle, or high gear ratio of the first transmission mechanism 3 described above to mechanically drive the output shaft 12. The gear ratios are shown in Figure 3, with low being 2.448, middle 1.399, and high 0.902. Meanwhile, the torque acting on the sun gear 32 generates electricity in the first MG 20, and the resulting power is supplied to the second MG 22, which then drives the output shaft 12 via the second transmission mechanism 4, applying the aforementioned low (2.448) and high (0.902) gear ratios. In other words, the torque of the sun gear 32 is electrically transmitted to the output shaft 12. That is, the first transmission mechanism 3 operates in a mechanical transmission path, and the second transmission mechanism 4 operates in an electrical transmission path. The rotational speed ratio between the input shaft 10 and the output shaft 12 changes steplessly according to the vehicle-side drive load acting on the output shaft 12 and the power of the engine 1. As the vehicle speed increases, the first MG 20 eventually stops along with the sun gear 32. In this case, the first MG20 stops and the aforementioned electrical transmission becomes zero, so it can be considered that all of the input torque is transmitted mechanically. The gear ratio at which this electrical transmission becomes zero is generally called the mechanical point. The gear ratio at this mechanical point (rotational speed of the input shaft / rotational speed of the output shaft) is the ICE gear ratio multiplied by 1 / (1 + ρ), and the gear ratio near this mechanical point has low electrical transmission loss, resulting in high power transmission efficiency. When the gear ratio becomes smaller than the mechanical point, the second MG22 generates electricity and drives the first MG20 in reverse rotation, and the "G" and "D" of both are reversed in the operation table in Figure 3.

[0033] Next, in reverse H-R mode, the gear ratio mechanically transmitted from the ring gear 34 to the output shaft 12 by the shift of each sleeve shown in Figure 3 is 1.399. However, since the ring gear 34 only produces torque in the direction in which the vehicle moves forward, it has a negative effect on the torque in reverse. However, in reality, the torque of the input shaft 10 is small when reversing, and the torque driven by the second MG 22 is sufficiently large, so this does not pose a practical problem. As is well known, when the vehicle is stopped, the first MG 20 is rotated in reverse with the sleeve in the shift state of H-1 or H-R as shown in Figure 3, and when the vehicle is in motion, the first MG 20 is made to generate electricity regardless of the drive mode.

[0034] Here, we will explain the operation from starting to high speed during forward driving in order. Starting is generally done in EV mode. Starting in E-L mode, and depending on the driving conditions such as vehicle speed and accelerator pedal depression, starting engine 1 switches to H-1 mode in HV mode. While driving in H-1 mode, switching to H-2 mode is done depending on the driving conditions. This switching is done while the second transmission mechanism 4 is transmitting power in low gear, as described above. At this time, the torque of engine 1 is reduced to bring the torque acting on the first sleeve 34d close to zero, and the first sleeve 34d is set to neutral. At the same time as reducing the torque of engine 1, the torque of the second MG 22 is increased to control the torque so that the torque of the output shaft 12 does not decrease significantly. In parallel, the rotational speed of engine 1 and the first MG 20 is immediately controlled so that the speed difference between the first sleeve 34d and the second gear 34c is close to zero, and the first sleeve 34d is shifted to the right. Immediately controlling the torque of engine 1 and second MG22 will shift to H-2. Subsequent switching to H-3 and H-4, or the reverse switching from H-4 to H-3, is basically done in the same way depending on the operating conditions, but as mentioned above, it is done when the power is being transmitted at a gear ratio in which the gear ratio switching of the first transmission mechanism 3 and the second transmission mechanism 4 is possible. Also, controlling the torque acting on the sleeve in question to a state close to zero to neutralize it when switching the gear ratio, and controlling the speed difference between the sleeve and the mating gear connected to it to a state close to zero to connect the two, are common to all switching. Furthermore, controlling the torque of the second MG22 or engine 1 to prevent large fluctuations in the torque of the output shaft 12 during the switching is also common to all switching. That is, when shifting the second sleeve 12d, the torque of the second MG22 is reduced and at the same time the torque of engine 1 is increased to control the output shaft 12 so that the torque does not decrease significantly.

[0035] The above describes the switching while the vehicle is driven by engine 1. However, if the accelerator pedal is pressed down less while driving, for example, engine 1 will immediately stop and the vehicle will switch to EV mode. In EV mode, no torque acts on the first sleeve 34d, so the torque control described above is unnecessary, and the first sleeve 34d can be switched by controlling the rotational speed alone. While driving, switching between EV mode and HV mode, and the above-described switching within HV mode, occurs frequently depending on the driving conditions. In all switching operations, the torque of the output shaft 12 is controlled so that the driver does not feel any discomfort.

[0036] Next, let's explain the role of the OWC12j. As mentioned above, with respect to torque in the direction of moving the vehicle forward, the OWC12j allows torque to be transmitted from the sixth gear 12g to the output shaft 12 without waiting for the connection between the second sleeve 12d and the sixth gear 12g. Therefore, as mentioned above, the control to bring the speed difference between the second sleeve 12d and the sixth gear 12g closer to zero can be omitted, and torque can be transmitted from the sixth gear 12g to the output shaft 12. For example, when switching from H-4 or H-3 to H-2 or H-1, the switch can be made quickly, especially when the accelerator pedal is suddenly pressed.

[0037] The gear ratios described above assume that the distance between the centers of the input shaft 10 and the output shaft 12 is the same as the distance between the centers of the output shaft 12 and the motor input shaft 40. If these two values ​​are different, the gear ratios will change to values ​​different from those described above. This should be determined by considering the required performance of the automobile and the characteristics of the engine 1.

[0038] The above describes the configuration and operation of Embodiment 1. This Embodiment 1 offers the following advantages. Specifically, because the output shaft 12 is arranged parallel to the input shaft 10, and the second MG 22 is also arranged parallel to the input shaft 10, the axial length can be significantly shortened, making it easier to mount in front-wheel-drive vehicles with a transversely mounted engine. Furthermore, since the torque of the second MG 22 is driven with a two-stage gear ratio by the action of the second transmission mechanism 4, even if the capacity of the second MG 22 is reduced in relation to the engine 1, as in the conventional example, acceleration force equivalent to the original specification without a transmission mechanism can be obtained at low speeds. In addition, at high speeds, the high-speed drive can reduce the rotational speed of the engine 1, and this, combined with the effect of being able to reduce the capacity of the second MG 22, can be expected to improve fuel efficiency. This can be considered equivalent to the conventional example. In comparison with conventional examples, conventional examples use friction engagement devices such as clutches and brakes in the transmission section, resulting in pump losses for driving the hydraulic pump to operate the friction engagement devices, as well as friction losses caused by non-operating friction engagement devices during driving. In contrast, according to this embodiment, the gear ratio can be changed simply by switching the engagement of the dog clutch, and since there are fewer losses related to driving, a further improvement in fuel efficiency can be expected. Furthermore, compared to conventional gear changes that involve switching the engagement of friction elements, it is expected that the shock generated during switching will be reduced, leading to smoother driving. In other words, in this embodiment, one of the mechanical route and the electrical route in HV mode is set to a neutral state for switching (gear change), and during that time the other is set to a power transmission state and the output shaft torque is controlled to drive it, thereby suppressing gear change shock and enabling smooth switching. Moreover, the configuration is simple and the dimensions can be reduced.

[0039] (Embodiment 2) Next, an automobile drive system according to Embodiment 2 of the present invention will be described. Figure 6 is a skeleton diagram of the main parts of the automobile drive system according to Embodiment 2 of the present invention. In the following description, the parts that differ from Embodiment 1 will be described in detail, and parts that are substantially the same as those in Embodiment 1 will be given basically the same names and reference numerals and their descriptions will be omitted. The shaft arrangement diagram of Embodiment 2, which corresponds to Figure 2, will be omitted, but the arrangement in Embodiment 2 is basically the same as in Figure 2.

[0040] The difference between Embodiment 2 and Embodiment 1 lies in the different configurations of the first gear shifting mechanism 3 and the second gear shifting mechanism 4. Specifically, in Embodiment 2, the ring gear shaft 34a is integrally provided with the first gear 34b and the second gear 34c, and the fifth gear 12f and the sixth gear 12g, which mesh with the first gear 34b and the second gear 34c, are rotatably supported coaxially with the output shaft 12. The first sleeve 34d, positioned on the output shaft 12, shifts axially so that either the fifth gear 12f or the sixth gear 12g is selectively connected to the output shaft 12. These constitute the first gear shifting mechanism 3 of the present invention, centered on the first sleeve 34d.

[0041] Furthermore, the motor input shaft 14 has a driven gear 14c integrally provided with it, and the driven gear 14c is connected to the second MG 22 via a pinion 22a and an idler gear 22b. In this regard, the second MG 22 is arranged in the opposite axial direction to that in Embodiment 1. The motor input shaft 14 has a second sleeve 12d arranged coaxially and supports the third gear 14a and the fourth gear 14b coaxially so as to be rotatable, and either the third gear 14a or the fourth gear 14b is selectively connected by shifting the second sleeve 12d. The third gear 14a and the fourth gear 14b mesh with the aforementioned fifth gear 12f and the seventh gear 12h, which is integrally provided with the output shaft 12, respectively. These constitute the second speed change mechanism 4 of the present invention, centered on the second sleeve 12d. The parking gear 34h is integrally provided with the fourth gear 14b. The other components are basically the same as in Embodiment 1, so their explanation will be omitted.

[0042] To explain the operation of Embodiment 2, an operation table corresponding to FIG. 3 is shown in FIG. 7. As described above, the configurations of the first transmission mechanism 3 and the second transmission mechanism 4 are different from each other. The mechanical transmission path in which the first transmission mechanism 3 is involved has two gear ratios, low and high, and the electrical transmission path in which the second transmission mechanism 4 is involved has three gear ratios, low, middle, and high. Therefore, the EV mode is driven at three gear ratios. The values of each gear ratio are set as shown in the operation table of FIG. 7.

[0043] In the HV mode, reverse travel is performed by rotating the second MG2 2 in the reverse direction of forward rotation at H-1. The switching between H-1 to H-4 in the HV mode is basically the same as that described in Embodiment 1. However, as described above, the first transmission mechanism 3 can be driven at two gear ratios, low and high, and the gear ratio of the second transmission mechanism 3 can be switched in any driving state of low or high. The second transmission mechanism 4 can switch the gear ratio of the first transmission mechanism 3 in the driving state at middle. Since the rest is the same as in the case of Embodiment 1, the description is omitted.

[0044] In Embodiment 2, basically the same effects as in the case of Embodiment 1 can be obtained. However, as described above, since the number of gear steps of the first transmission mechanism 3 and the number of gear steps of the second transmission mechanism 4 are different, it can be said that the merit is that there is a degree of freedom in selecting either Embodiment 1 or Embodiment 2 according to the specifications and driving conditions of the automobile.

[0045] (Embodiment 3) Next, the vehicle drive device of Embodiment 3 of the present invention will be described. FIG. 8 is a skeleton diagram of the main part in the vehicle drive device according to Embodiment 3 of the present invention. In the following description, the parts different from Embodiment 1 will be mainly described, and for the parts substantially the same as those in Embodiment 1, basically the same names and reference numerals will be given and their descriptions will be omitted. Although the layout diagram of the shafts of Embodiment 3 corresponding to FIG. 2 is omitted, the layout in the case of Embodiment 3 is basically the same as that of FIG. 2.

[0046] The difference between Embodiment 3 and Embodiment 1 is the addition of a speed change mechanism between the input shaft 10 and the output shaft 12. Specifically, Embodiment 3 includes an additional eighth gear 10a rotatably supported on the input shaft 10, a ninth gear 12k which meshes with the eighth gear 10a and is integrally provided with the output shaft 12, and a third sleeve 10b provided on the input shaft 10. The third sleeve 10b is configured to shift axially, allowing the input shaft 10 to be selectively connected to either the second gear 34c or the eighth gear 10a. In other words, the second gear 34c can be connected to the ring gear shaft 34a by the first sleeve 34d, similar to Embodiment 1, so the second gear 34c is configured to be connectable to both the ring gear shaft 34a and the input shaft 10. In addition, the position of the parking gear 34h is different from that of Embodiment 1. The gear ratio between the eighth gear 10a and the ninth gear 12k (rotational speed of the input shaft 10 / rotational speed of the output shaft 12) is 0.800. The other configurations, including the gear ratios, are basically the same as in Embodiment 1, so their explanation is omitted.

[0047] To explain the operation of Embodiment 3, an operation table corresponding to Figure 3 is shown in Figure 9. As described above, a third sleeve 10b has been added compared to Embodiment 1, so the third sleeve 10b has been added to Figure 9 as S3. As described above, by shifting the third sleeve 10b, the input shaft 10 and output shaft 12 can be mechanically connected by the second gear 34c and the seventh gear 12h and the eighth gear 10a and the ninth gear 12k, respectively. This is classified as a high-efficiency drive, and it is shown that two gear ratios, "M-1" and "M-2", can be obtained. The ICE gear ratio for the high-efficiency drive is (rotational speed of the input shaft 10) / (rotational speed of the output shaft 12). In addition, the first sleeve (S1) 34d and the second sleeve (S2) 12d do not participate in power transmission in the high-efficiency drive, but the C in parentheses in the table indicates that switching may occur during operation in high-efficiency drive. Furthermore, the second MG22 can operate even in high-efficiency drive mode, but the "G" and "D" markings are not displayed.

[0048] In the driving mode of Embodiment 3, the E-CVTs in the EV mode and the HV mode are basically the same as those in Embodiment 1, so the description thereof is omitted. On the other hand, since it is different from Embodiment 1 in high-efficiency driving, this will be described in detail. As described above, by shifting the third sleeve 10b, two-stage gear ratios of M-1 and M-2 are obtained, and power is mechanically transmitted from the input shaft 10 to the output shaft 12, different from the E-CVT. Therefore, high-efficiency driving can be achieved under driving conditions suitable for this gear ratio. As other functions, M-1 and M-2 can participate in the switching in the E-CVT.

[0049] For example, when switching from H-1 to H-2 or H-3, it is performed via M-1. That is, when traveling in H-1 and approaching the gear ratio of M-1, the rotational speed difference between the second gear 34c and the first sleeve 10b approaches 0. Therefore, by shifting the third sleeve 10b to the left side in FIG. 8 here, the drive can be switched to M-1. During the drive in M-1, the first sleeve 34d and the second sleeve 12d can be freely switched. After connecting them to H-2 or H-3, the switch is made from M-1 to H-2 or H-3. This switching can be performed with almost no change in the torque of the output shaft 12 even when the engine 1 is driving at full power, which is different from the switching of the E-CVT described in Embodiment 1. Therefore, in relatively low-load driving, it can be used separately, such as switching at an arbitrary gear ratio according to the driving conditions as described in Embodiment 1, and performing switching via M-1 in high-load driving. That is, in low-load driving, importance is attached to the fact that it can be switched at an arbitrary gear ratio, and in high-load driving, importance is attached to the fact that the gear ratio to be switched is limited but the torque change of the output shaft 12 is small. Similarly, the switching from H-3 to H-4 can be performed via M-2, and in the switching from H-4 to H-3 and from H-3 or H-2 to H-1, it can be performed in the reverse order.

[0050] This third embodiment offers the following advantages in addition to the effects obtained in the first embodiment. Specifically, the addition of the highly efficient M-1 and M-2 drives allows for further improvements in fuel efficiency, particularly during cruising. Furthermore, utilizing M-1 and M-2 for E-CVT switching makes switching smoother, especially during high-load driving. Although we have described providing two stages, M-1 and M-2, for high-efficiency driving, M-1 is more effective in smoothing E-CVT switching during high-load driving. Therefore, considering factors such as the axial length of the drive unit and manufacturing costs, it is also advantageous to omit the eighth gear 10a and the ninth gear 12k and use only M-1.

[0051] The automotive drive system of the present invention can be implemented in a manner that combines control features such as optimal setting of each gear ratio, optimization of bearing arrangement, and selection method of drive mode, based on the general knowledge of those skilled in the art.

[0052] The automotive drive system of the present invention can be applied to passenger cars and commercial vehicles that require smooth gear changes, particularly low running costs, and reduced environmental impact. However, it is not limited to these vehicles and can be applied to a variety of vehicles that utilize internal combustion engines and motor-generators.

[0053] 1 Engine 3 First transmission mechanism 4 Second transmission mechanism 10 Input shaft 12 Output shaft 14 Motor input shaft 20 First motor-generator (MG1) 22 Second motor-generator (MG2) 30 Planetary gear

Claims

1. An automobile drive system comprising: an input shaft capable of receiving power from an engine; an output shaft arranged parallel to the input shaft; a planetary gear consisting of three rotating elements, a sun gear, a ring gear, and a carrier, and a first motor-generator, arranged on the same axis as the input shaft; a second motor-generator arranged parallel to the input shaft; and a first and second gear shift mechanism, each having at least two gear ratios, low and high; wherein the input shaft is connected to the carrier, the first motor-generator is connected to the sun gear, the ring gear can be connected to the output shaft via the first gear shift mechanism, the second motor-generator can be connected to the output shaft via the second gear shift mechanism, and the first and second gear shift mechanisms are configured to allow switching of the gear ratio while one of them is transmitting power.

2. The automobile drive device according to claim 1, comprising a ring gear shaft integrally provided with the ring gear and a motor input shaft connected to the second motor generator, wherein the first speed change mechanism is arranged between the ring gear shaft and the output shaft, and the second speed change mechanism is arranged between the motor input shaft and the output shaft.

3. The automobile drive system according to claim 2, characterized in that the ring gear shaft and the motor input shaft are arranged on both sides of the output shaft, and the ring gear shaft and the motor input shaft can be connected via the first transmission mechanism and the second transmission mechanism.

4. The drive device for an automobile according to claim 2, characterized in that the ring gear shaft is selectively connectable to a first gear and a second gear arranged coaxially, the motor input shaft is integrally provided with a third gear and a fourth gear, and the output shaft rotatably supports a fifth gear meshing with the first gear and the third gear, and a sixth gear meshing with the fourth gear, and is selectively connectable to the fifth gear and the sixth gear, and integrally provides a seventh gear meshing with the second gear.

5. The automobile drive system according to claim 4, characterized in that the input shaft and the output shaft can be connected with at least one gear ratio.

6. The automobile drive device according to claim 2, characterized in that the ring gear shaft is integrally provided with a first gear and a second gear on the same axis, the motor input shaft is selectively connectable to a third gear and a fourth gear on the same axis, and the output shaft rotatably supports a fifth gear meshing with the first gear and the third gear, and a sixth gear meshing with the second gear, and is selectively connectable to the fifth gear and the sixth gear, and integrally provides a seventh gear meshing with the fourth gear.

7. The automobile drive system according to claim 4 or 6, characterized in that the output shaft and the sixth gear can be connected by a one-way clutch.

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