JP3578212B2 - Drive - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a drive device suitable for a hybrid vehicle equipped with a plurality of power sources such as an engine or a motor, and more particularly to a drive device capable of performing a continuously variable transmission operation by a differential device such as a planetary gear mechanism. .
[0002]
[Conventional technology and problems to be solved]
As a drive device using this type of differential device, for example, a hybrid vehicle having a configuration in which a generator, an engine, and a drive system motor are respectively connected to three elements of a sun gear, a planet carrier, and a ring gear constituting a planetary gear mechanism. drive device is known (see Japanese Patent Laid-open 2 000-142146). According to this drive device, a part of the engine output is distributed to the drive of the generator using the differential function of the gears, and the generated power is supplied to the motor, so that the continuously variable transmission and the increase and decrease of the output torque can be performed. It can be carried out.
[0003]
However, in such a conventional drive device, it is difficult to increase mechanical energy passing through the planetary gears due to mechanical restrictions, so that the generator and the motor need to be large. In particular, since the ratio of the power passing through the generator and the motor to the power passing through the differential gear approaches 1 on the low speed side and cannot be increased any more, it is necessary to ensure sufficient driving force at the time of starting. Requires a generator and a motor having a power as high as that of an engine on the side of the engine, which increases the size and weight of the drive device and lowers the efficiency.
[0004]
The present invention has been made in view of such a conventional problem. In a two-degree-of-freedom differential having three or more elements, a specific element can be provided with a brake to suppress the rotation of the element. Accordingly, it is possible to provide a driving device capable of obtaining a large driving force from the stopped state.
[0005]
[Means for Solving the Problems]
A first invention includes a two-degree-of-freedom differential device in which five input / output elements are arranged on a collinear chart, and the five elements are provided with a motor / generator, an input, a brake, Output, motor / generator assigned.
[0006]
In a second aspect, a clutch is provided between the engine and the input element.
[0007]
In a third aspect, the brake according to the first aspect is engaged when the required driving force is large.
[0008]
In a fourth aspect based on the first aspect, the driving force generated by the motor / generator is reduced in accordance with an increase in vehicle speed during the operation of the brake, and the transmission force at the brake becomes near zero under the brake-off operating condition. As a result, the driving force difference when the brake is off is reduced.
[0009]
In a fifth aspect, the differential device according to the first aspect is constituted by a planetary gear mechanism.
[0010]
According to a sixth aspect, the planetary gear mechanism of the fifth aspect includes a first planetary gear train of a single pinion type and a second planetary gear train of a double pinion type, and each of a sun gear, a carrier, and a ring gear. Any two elements are shared to form a two-degree-of-freedom differential device.
[0011]
【The invention's effect】
First invention In a two-degree-of-freedom differential device having four or more elements as in each of the following inventions, the speed of any two elements is determined by the speed of any two elements. In such a differential device, it is possible to set a large reduction ratio between the power source and the drive system by providing a brake on an element other than the element to which the output to the drive system is allocated and braking the element. As a result, the startability can be improved without increasing the capacity of the motor / generator. In particular, in the present invention, since the brake is provided in the element located between the input and output, the output is reversed when the brake is actuated, and the gear ratio at that time can be set to a low speed gear, so that a large driving force can be obtained when the vehicle retreats. . Such a two-degree-of-freedom differential can be constituted by, for example, a planetary gear mechanism as described in the fifth or sixth aspect.
[0012]
According to the second aspect , since the engine can be disconnected by the clutch, the vehicle can be driven only by the motor / generator without dragging the engine, and the efficiency of the electric traveling can be improved. Also, a large driving force can be generated by operating the brakes during electric running, but if the forward or backward movement is performed with the same brake operated, the input differential element will rotate in the reverse direction on either one Will be. At this time, by separating the engine, reverse rotation of the engine can be prevented.
[0013]
According to the third aspect , when a large driving force is required at a low vehicle speed, the driving force can be generated by the torque of at least one of the engine and the two motors / generators at a fixed low gear ratio, so that a large driving force is obtained. Is obtained.
[0014]
According to the fourth aspect , a change in the driving force when the brake is off is small, and a smooth driving force characteristic can be obtained.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment in which the present invention is applied to a power transmission device (transaxle) for a front wheel drive vehicle will be described with reference to the drawings. FIG. 1 and FIG. 2 show schematic diagrams and collinear charts of different configuration examples .
[0016]
FIG. 1 is a reference example for explaining the basic operation of a five-element differential device, and FIG. 2 is an embodiment of the present invention. Common members are denoted by the same reference numerals .
In each figure , Hm is a motor housing, Ct is a transmission casing, Hc is a clutch housing, and Ha is an axle housing. The clutch housing Hc is provided with a clutch CL for connecting or disconnecting the engine output shaft Je and the transmission input shaft Jr1. In the transmission, a single pinion planetary gear train P1 and a double pinion planetary gear train P2 are connected to each other in such a manner that they share a ring gear R and a carrier C, and are housed in a casing Ct. The input shaft Jr1 to which the clutch CL is connected is the P1 ring gear shaft. In FIG. 1, the input shaft Jr1 is provided with a one-way clutch CLo for preventing reverse rotation of the engine. In addition, in the code | symbol which shows the component of a planetary gear train, the subscript 1 shows the thing of the 1st planetary gear train P1, and 2 shows the thing of the 2nd planetary gear train P2. Further, the structure of the double pinion type planetary gear train is shown in a diagram developed in a cross section passing through two pinion shafts for convenience (the same applies to the following configuration diagrams).
[0017]
In the motor housing Hm, an inner rotor Rmi and an annular outer rotor Rmo are coaxially supported, and a small electric machine functioning as two motor / generators MGi and MGo is constituted by these. An annular coil Cm is provided between the inner and outer rotors Rmi and Rmo, and each of the rotors Rmi and Rmo can be individually operated as a generator or a motor by the coil Cm. The inner rotor shaft Jmi penetrates the hollow outer rotor shaft Jmo and is connected to the sun gear S1 of P1, and the outer rotor shaft Jmo is connected to the sun gear S2 of P2. Ssi and Sso in FIG. 1 are rotation sensors for measuring the rotation speed of the inner rotor shaft Jmi and the outer rotor shaft Jmo, respectively. In the reference numerals indicating the components of the motor / generator, the suffix i indicates that of the first motor / generator MGi, and o indicates that of the second motor / generator MGo.
[0018]
The axle housing Ha is provided on a side surface of the transmission casing Ct, and inside the gear housing Ha, a reduction mechanism Fin and a drive axle Drv are supported in parallel with the planetary gear mechanism. In FIG. 1, the rotation of the carrier C is transmitted to the final reduction gear Fin via a reduction gear Rg. That is, in this case, the carrier shaft Jc is an output shaft connected to the final reduction gear Fin that is a drive system. On the other hand, in FIG. 2, the ring gear R2 of the second planetary gear train P2 is assigned to the output, and the driving force is extracted from the rotation shaft Jr2 to the reduction gear Rg.
[0019]
In FIG. 1, an inner pinion pi common to P2 meshes with a sun gear S1 of P1, and a ring gear R3 coaxially supported with a ring gear R of P1 meshes with an outer pinion po of P2 meshing with the inner pinion pi. In addition, a brake B for braking the rotation of the ring gear R3 is provided on the casing Ct. On the other hand, in the embodiment of the present invention shown in FIG. 2, the carrier C shared by the first planetary gear train P1 and the second planetary gear train P2 is braked by the brake B. Different from the ones .
[0020]
In the configuration of FIG. 1, by braking the ring gear R3 by the brake B, a large reduction ratio can be set as shown in the alignment chart of FIG . 1 and FIGS. The driving force and starting performance of the vehicle can be improved. The reference symbol EV on the alignment chart indicates the characteristic at the time of traveling only by the motor / generator, START indicates the characteristic at the time of starting with the brake B applied, MAX indicates the characteristic at the maximum vehicle speed, and REV indicates the characteristic at the time of reverse. . The symbol Out indicates an output to the drive system, and In indicates an input from the engine. On the other hand, in the configuration of the embodiment shown in FIG. 2, the rotation of the output shaft can be reversed when the brake B is actuated, as can be seen from the comparison with the alignment chart of FIG. A large driving force can be exhibited by obtaining a reduction ratio .
[0021]
Here, the alignment chart will be described. The alignment chart is a graph in which the number of teeth is distributed on the horizontal axis, and the rotation speed of each element is expressed in the vertical axis on the points distributed by the tooth number ratio. The rotation speed of each element is always represented by a linear relationship proportional to the gear ratio. As shown in the figure , when two sets of planetary gear trains are combined in such a manner that the ring gear and carrier of the first planetary gear train P1 are shared with the ring gear and carrier of the second planetary gear train P2, they can be connected to the input / output side. The essential elements are the sun gear S1 of the first planetary gear train P1, the sun gear S2 of the second planetary gear train P2, the carrier C shared by each planetary gear train, and four elements (five elements if the ring gear R3 is added). . Such a compound planetary gear mechanism is known as a type of a so-called Ravigneawx planetary gear set. This composite planetary gear mechanism has two degrees of freedom, that is, when the rotational speed of any two elements is determined, the rotational speed of the other elements is determined.
[0022]
Now, assigning the input from the engine and the output to the drive system to any two of the four elements other than the ring gear R3, and connecting the motor / generator to each of the remaining two elements, the speed between the input and the output There are a wide variety of two motor / generator speed combinations that provide a ratio. Therefore, it is possible to select a combination that minimizes the energy borne by the motor / generator from the combinations. In particular, in the present embodiment, the input In from the engine and the output Out to the drive system are assigned to the two elements inside the alignment chart, and the motor / generators MGo and MGi are connected to the two outside elements sandwiching these, respectively. Therefore, the torque borne by the motor / generator with respect to the engine output can be made smaller, in other words, the energy passing through the motor / generator can be made smaller, so that the transmission efficiency as a drive device is effectively improved. be able to.
[0023]
On the other hand, in a state where the ring gear R3, which is the fifth element in FIG. 1 , is braked by the brake B, the rotations of the three drive sources are reduced at respective individual reduction ratios as seen in the START characteristic line of the alignment chart. Since it functions as a speed reducer that transmits the rotation to the carrier C connected to the drive system, it is possible to secure a good starting performance with a power source having a relatively small output.
[0024]
More specifically, when the vehicle is moving forward, in the brake-on state in which the ring gear R3 is braked, the second motor / generator MGo is moved forward, the engine (input In) is moved forward, and the first motor / generator MGi is moved forward. When a torque is generated to the reverse rotation side, a torque in the forward direction is generated at the output portion Out. The torque at this time is transmitted from the two motors / generators MGi and MGo and the input In to the output Out, with the torque amplified at an individual ratio, whereby a large driving force is obtained.
[0025]
If it is attempted to increase the output rotation with the brake on, the two motor / generators MGi, MGo and the engine become high in rotation, and the rotation of the output Out cannot be sufficiently increased from the respective rotation limits. Therefore, in this case, the brake is turned off so that the ring gear R3 can rotate, and the rotation of the first motor / generator MGi is changed from reverse rotation to stop and forward rotation, so that the output without increasing the rotation on the input In side. The rotation can be raised.
[0026]
The maximum drive power that can be generated is greater when the brake is on than when it is off, but the output torque of the motor / generator is controlled so as to reduce the change in drive power when the brake is off, resulting in a smooth drive force characteristic. Can be
[0027]
Note that when the brake is turned on, it is possible to transmit the torque to the output Out by generating torque in any one of the driving sources, and both motors / generators can be turned from the outside.
[0028]
When the brake is off, power is generated by one motor / generator, and the other motor / generator is driven by the electric power. At this time, by controlling the rotation speed and the torque of the two motors / generators, it is possible to obtain an arbitrary speed ratio (ratio between the rotation speed of the input In and the rotation speed of the output Out) while the power balance is balanced. Yes (see MAX in collinear chart). Also, by increasing the output on the driving side, it is possible to output an output higher than the engine power.
[0029]
Further, when the brake is off, there are two speed ratios at which the rotation of the first or second motor / generator becomes zero, and the two points can be operated without electrically transmitting power. In addition, in the transmission ratio between the two points, the ratio of the power transmitted electrically, which is lower in efficiency than the mechanical transmission, to the power transmitted as the transmission can be reduced, so that the transmission efficiency can be improved. it can. In addition, it is also possible to output using two motor / generators MGi and MGo for driving, and electric running is possible. At this time, by releasing the engagement of the input clutch CL, it is possible to operate with low friction without dragging the engine.
[0030]
In reverse, when the brake is on, torque is generated in the output Out in the reverse direction by generating torque in the second motor / generator MGo to the reverse rotation side and generating torque in the first motor / generator MGi to the normal rotation side. be able to. Thus, when the output is reversed, the engine rotation is also in the reverse direction. At this time, the clutch is turned off. In this case, the one-way clutch CLo for preventing reverse rotation is not provided.
[0031]
By driving both motors / generators MGi and MGo in the reverse rotation direction with both the brake and the clutch off, electric traveling can be performed. In the state where the clutch is on and the brake is off, the first motor / generator MGi is driven in the reverse rotation direction and the second motor / generator MGo generates power, so that the operation can be performed with the power balance being balanced. .
[0032]
FIG. 3 shows the maximum driving force in various states when the above configuration is applied to a hybrid vehicle, and FIG. 4 shows the ratio (output sharing ratio) of the power passing through the motor / generator to the transmission power in a state where the power balance is balanced. ing. In FIG. 3 , a1 and a2 are the maximum driving force characteristics when battery power is used and when brake B is not used when brake B is not used. On the other hand, b1 and b2 are the maximum driving force characteristics when the battery power is used when the brake B is used and when it is not used. As shown in the figure, a large driving force can be obtained in a low speed region including starting by using the brake. Note that c indicates the maximum driving force characteristic during electric traveling using only the power of the motor / generator, and d indicates the driving force characteristic when the driving force is controlled to change smoothly.
[0033]
On the other hand, “ Characteristic (1)” and “ Characteristic (2)” in FIG. 2 are different from each other only in the setting of the final deceleration stage of the vehicle. It can be operated in a state of 30% or less. As can be seen from these figures, when the differential device is applied, a lower output motor / generator can be applied and the transmission efficiency can be improved. Note that “SHV” in FIG. 2 is a series hybrid vehicle, and the output sharing ratio is always 1 because all of the engine output is used for driving the generator.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a reference example related to the present invention.
FIG. 2 is a schematic configuration diagram of an embodiment of the present invention.
FIG. 3 is a characteristic diagram showing maximum driving force characteristics in various states according to the reference example.
FIG. 4 is a characteristic diagram showing an output sharing characteristic of an electromechanical system with respect to an engine output according to the reference example in relation to a vehicle speed.
[Explanation of symbols]
P1 First planetary gear train P2 Second planetary gear train S, S1, S2 Sun gear R, R1, R2 Ring gear C, C1, C2 Carrier (planet carrier)
p, pi, po Pinion CL Clutch B, B1, B2 Brake CLo One-way clutch Fw Flywheel MGo First (outer) motor generator MGi Second (inner) motor generator Cm, Cmi, Cmo Coil Hc Clutch housing Hm Motor housing Ct Transmission casing Ha Axle housing Ssi, Sso Rotation sensor Rg Reduction gear Fin Final reduction gear Drv Drive axle

Claims (6)

A two-degree-of-freedom differential device in which five input / output elements are arranged on the alignment chart,
A drive device, wherein a motor / generator, an input, a brake, an output, and a motor / generator are assigned to the five elements in order of rotation speed. The drive device according to claim 1, wherein a clutch is provided between the engine and the input element. The drive device according to claim 1, wherein the brake is applied when a required drive force is large. The driving force generated by the motor / generator is reduced in accordance with the increase of the vehicle speed during the operation of the brake, so that the transmission force at the brake becomes nearly zero under the driving condition of the brake off, and the driving force difference at the time of the brake off is small. The drive device according to claim 1, wherein the drive is performed. The drive device according to claim 1, wherein the differential device is configured by a planetary gear mechanism. The planetary gear mechanism includes a first planetary gear train of a single pinion type and a second planetary gear train of a double pinion type, and shares any two elements of the respective sun gear, carrier, and ring gear to achieve 2 The driving device according to claim 5, which constitutes a differential device having a degree of freedom.

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