JP2011140266A - Device for driving hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for driving a hybrid vehicle, which reduces an energy loss due to the drag torque of an engine in motor traveling or fuel cut deceleration, and which acts as a speed reducer in start of an engine and regulates the reverse rotation of the engine to thereby prevent such a failure as lubrication failure, and which dispenses with control of a hydraulic device or electric apparatus and has a simple structure as a result. <P>SOLUTION: A power transmission mechanism includes: a planetary gear configured of a first rotating element connected via a first one-way clutch with a fixed member, a second rotating element connected with the output shaft of an engine and a third rotating element connected with a motor generator; a first one-way clutch for preventing the rotating direction of the first rotating element from being reverse to the direction of the engine; and a second one-way clutch for preventing the rotational speed of the second rotating element from being higher than the rotational speed of the third rotating element. When the engine is started, the first one-way clutch is operated, and the output of the motor generator is transmitted via the planetary gear to the engine. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a drive device for a hybrid vehicle, and in particular, a hybrid vehicle that prevents the engine as a power source from rotating in the reverse direction different from the normal rotation direction and prevents the occurrence of problems due to the reverse rotation of the engine. It is related with the drive device.

One of the driving systems of a hybrid vehicle including an engine and a motor generator is a parallel system as disclosed in Patent Document 1 and Patent Document 2. In this parallel system, the engine and the motor generator are connected in parallel, and both are used together to drive the wheel, so that even a small output motor can travel. In addition, the parallel system has a simple structure compared to other systems, the increase in weight and cost due to hybridization is kept low, and the driving force of the engine can be transmitted directly to the drive shaft, thus reducing energy consumption. There is an advantage that loss is small.
On the other hand, in the parallel system, when the motor generator is driven while the engine is stopped, the motor generator and the output shaft are always dragged by the engine. Therefore, in the parallel system, energy loss increases both when running with the power generated by the motor generator (motor running) and when regenerating by driving the motor generator with external force during deceleration. There is a problem that the degree of freedom of the engine operating point is smaller than that of this method.

To solve this problem,
(1) A method in which a clutch is provided between the engine and the motor generator, and the both are mechanically disconnected as required (Patent Document 3, Patent Document 4),
(2) A method of reducing engine friction by cylinder deactivation (Patent Document 5),
Furthermore, (3) the hydraulic clutch that separates the power source and the drive shaft and the two one-way clutches installed between the engine and the motor generator are electromagnetically controlled so that the engine friction is not transmitted to the motor. (Patent Document 6),
(4) A planetary gear mechanism and a one-way clutch are provided between the engine and the motor generator, and act as a speed reducer when the engine is started. After the engine is started, the engine and the motor generator are directly connected to generate power (Patent Document 7). -Patent Document 10), etc.
Various means have been proposed.

Japanese Patent Laid-Open No. 9-4479 Japanese Patent Laid-Open No. 11-350995 German Patent Publication No. 33 20 950 German published patent publication 37 37 192 JP 2004-27849 A Japanese Patent No. 2004-17942 Japanese Patent No. 3884743 JP-A-2005-299406 JP 11-182279 A JP 2004-278367 A

  However, with regard to (1), there are many disadvantages in terms of vehicle mounting, such as requiring a complicated mechanical device including a large-scale hydraulic system device and an electrical mechanism by a large number of sensors and program control circuits. There is a problem. Regarding (2), since complex engine control is required, there is a problem that there is no versatility applicable to vehicles of any engine. Regarding (3), there is a problem that complicated control of the engagement switching tool of the hydraulic clutch and the one-way clutch according to the traveling state is required. Furthermore, regarding (1) and (3), there is a problem that the effect cannot be exhibited if it is not desired to completely stop the engine during the fuel injection cut at the time of deceleration, and there is still room for improvement. With regard to (4), the motor generator can only act as a generator, and another motor needs to be added in order to perform travel assistance.

  Also, in a drive device in which the engine and motor generator are coupled via a planetary gear mechanism, the rotation direction of the engine rotates in the opposite direction (negative rotation) from the normal rotation direction (forward rotation) due to malfunction of the motor generator. In this case, there are various problems such as poor lubrication of the engine.

  This invention reduces energy loss due to dragging during motor running or fuel cut deceleration, and acts as a speed reducer at the time of engine start, and prevents problems such as poor lubrication by restricting reverse rotation of the engine, An object of the present invention is to provide a drive device for a hybrid vehicle having a simple structure that does not require control of a hydraulic device or an electrical device.

  The present invention provides a drive device for a hybrid vehicle that outputs power generated from an engine and a motor generator to a drive shaft via a power transmission mechanism, wherein the power transmission mechanism is connected via a fixed member and a first one-way clutch. A planetary gear comprising a first rotating element in communication, a second rotating element in communication with at least the output shaft of the engine, and a third rotating element in communication with the motor generator, and rotation of the first rotating element A rotation speed of the second rotation element provided between the first one-way clutch, the second rotation element, and the third rotation element for preventing the direction from being opposite to the rotation direction of the engine; And a second one-way clutch that prevents the rotational speed of the third rotating element from becoming higher than the rotational speed of the third rotating element. Is, the output of the motor-generator, characterized in that it transmitted to the engine via the planetary gear.

  In the hybrid vehicle drive device of the present invention, the engine speed can be set lower than that of the motor when the engine is stopped or the torque is not output due to fuel cut, and the engine is operating and the torque is being output. Then it can be directly connected to the motor. Further, reverse rotation of the engine can be prevented by the first one-way clutch. As a result, this hybrid vehicle drive device reduces energy loss due to drag of the engine during motor running or fuel cut deceleration, acts as a speed reducer when starting the engine, and restricts reverse rotation of the engine. It is possible to prevent problems such as poor lubrication.

It is a schematic block diagram of the drive device of a hybrid vehicle. (Example) It is an alignment chart of a stop state. (Example) It is an alignment chart at the time of motor running and engine starting. (Example) It is an alignment chart immediately after engine start and after fuel injection cut recovery. (Example) It is an alignment chart at the time of engine operation and vehicle stop. (Example) It is an alignment chart at the time of start and acceleration. (Example) It is an alignment chart at the time of deceleration. (Example) It is an alignment chart at the time of idle stop. (Example) It is a schematic block diagram of the drive device of a hybrid vehicle. (Modification) It is an alignment chart at the time of start and acceleration. (Modification)

  Embodiments of the present invention will be described below with reference to the drawings.

1 to 8 show an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a drive device for a hybrid vehicle. The drive device 1 outputs the power generated from the engine 2 and the motor generator 3 to the drive shaft 5 via the power transmission mechanism 4. The engine 2 includes an output shaft 6 and generates power by burning fuel. The engine 2 is automatically stopped and started (idle stop) by the engine control means, and the fuel injection is cut during deceleration. The motor generator 3 includes a motor shaft 7, a motor rotor 8 fixed to the motor shaft 7, and a motor stator 9 disposed on the outer periphery of the motor rotor 8. The motor generator 3 generates power by supplying electricity and generates electric energy by driving with an external force. To do.
The drive device 1 connects the output shaft 6 of the engine 2 and the motor shaft 7 of the motor generator 3 via the power transmission mechanism 4, and connects the motor shaft 7 to the drive shaft 5. The power transmission mechanism 4 exchanges power between the engine 2, the motor generator 3, and the drive shaft 5. The drive shaft 5 is connected to the input shaft 11 of the transmission 10. Between the drive shaft 5 and the input shaft 11, a shock absorber 12 such as a clutch or a torque converter for buffering a rotational deviation from the transmission 10 side is interposed. The output shaft 13 of the transmission 10 is connected to drive wheels. Motor generator 3 is controlled by inverter 14. A power supply terminal of the inverter 14 is connected to a battery 15 that is a power storage device.

The power transmission mechanism 4 includes a planetary gear 16, a first one-way clutch 17, and a second one-way clutch 18. The planetary gear 16 includes a sun gear 19 that is a first rotating element, a planetary carrier 21 that is a second rotating element that supports a planetary gear 20 that meshes with the sun gear 19, and a ring gear 22 that is a third rotating element that meshes with the planetary gear 20. The sun gear 19 is in communication with the device case 23 that is a fixing member via the first one-way clutch 17. The planetary carrier 21 is in communication with at least the output shaft 6 of the engine 2. The ring gear 22 is connected to the motor shaft 7 of the motor generator 3 via the ring gear-motor shaft connecting member 24.
The first one-way clutch 17 is provided between the sun gear 19 and the device case 23 by interposing a sun gear-case connecting member 25 that connects the sun gear 19 and the device case 23 so that the engine 2 is spontaneously operated. When the rotation direction (normal rotation direction) is a positive rotation, the sun gear 19 is prevented from becoming a negative rotation, and is provided on the positive rotation side in a direction of idling. Therefore, the first one-way clutch 17 prevents the rotational direction of the sun gear 19 from being opposite to the rotational direction of the output shaft 6 of the engine 2.
The second one-way clutch 18 is inserted into a carrier-ring gear connecting member 26 that connects the output shaft 6 connected to the planetary carrier 21 and the ring gear connecting member 24 connected to the ring gear 22, so that the planetary carrier 21 and the ring gear 22 are inserted. The planetary carrier 21 is prevented from having a rotational speed higher than that of the ring gear 22, and is provided in the direction of idling on the lower side. Therefore, the second one-way clutch 18 prevents the rotational speed of the planetary carrier 21 from becoming higher than the rotational speed of the ring gear 22.
The power transmission mechanism 4 operates the first one-way clutch 17 when the engine 2 is started, and transmits the output of the motor generator 3 to the engine 2 via the planetary gear 16.

Next, the operation will be described.
The drive device 1 of the hybrid vehicle acts as a speed reducer when the engine is started, directly connects the output shaft 6 and the drive shaft 5 of the engine 2 when the engine is running, and sets the engine speed to the motor generator 3 and the drive shaft 5 while the engine is stopped. The power transmission mechanism 4 is configured so as to be kept lower than the rotational speed. The power transmission mechanism 4 includes a planetary gear 16, a first one-way clutch 17, and a second one-way clutch 18.
Each operation state of the power transmission mechanism 4 will be described with reference to the alignment charts of FIGS. The rotational speed is defined as the positive direction of the rotation direction of the engine 2, and the torque input / output to / from each axis is defined as the positive direction in which the torque in the same direction as the torque of the engine 2 is input. Therefore, when the torque of the drive shaft 5 is positive, the torque to drive the hybrid vehicle forward is being output (drive when traveling forward, decelerate when traveling backward). When the torque is negative, the torque to drive the hybrid vehicle rearward is being output (deceleration during forward travel, drive during reverse travel).
In addition, on the alignment chart, in order from the left, the sun gear 19 (indicated as “S” on the alignment chart), the planetary carrier 21 (indicated on the alignment chart as “C”), and the ring gear 22 (common) The rotation speed axes of “R” in the diagram are vertically aligned, and the distance between the sun gear 19 (S) and the planetary carrier 21 (C): the planetary carrier 21 (C) and the ring gear 22 (R) Interval between and = 1: k.

(1) Stop state The charge amount of the battery 15 is sufficient, and the transmission 10 performs this control in the idle stop state in the D range or R range, or the transmission 10 performs in the N range / P range.
FIG. 2 shows an alignment chart in a stopped state. The engine 2 is stopped and no torque is generated in the motor generator 3.

(2) During motor travel and engine start This control is performed when travel (motor travel) is performed only with the motor generator 3 while the engine 2 is stopped, or when a start request for the engine 2 is received in a stopped state.
FIG. 3 shows a nomographic chart when the motor is running and the engine is started. When the motor travels, the first one-way clutch 17 of the power transmission mechanism 4 is in operation, and the relationship between the output shaft rotational speed Nout of the engine 2 and the engine rotational speed Ne2 at this time is as follows.
Ne2 = Nout / (1 + k) [rpm]
By using this drive device 1, in the case of a conventional parallel type hybrid vehicle, the relationship between the engine rotational speed Ne1 and the output shaft rotational speed Nout is Ne1 = Nout, so that the engine rotational speed is Ne1 compared to the conventional one. > Ne2, and the engine rotation speed during motor running can be further reduced.
Similarly, the relationship between the friction torque Te2 by the engine 2 and the torque loss Tloss2 exerted on the drive shaft 5 by the friction torque Te2 when the drive device 1 is used is as follows.
Tloss2 = Te2 / (1 + k) [Nm]

In the case of a conventional parallel type hybrid vehicle, assuming that the friction torque by the engine is Te1, the torque loss exerted by the friction torque Te1 on the drive shaft 5 is Tloss1 = Te1, and the friction torque is Te1 from the relationship Ne1> Ne2. Since> Te2, the torque loss becomes Tloss1> Tloss2. Therefore, by using this drive device 1, it is possible to further reduce the friction torque that the drive shaft 5 receives due to the drag of the engine 2 when the motor is running.
Further, when the engine 2 is started, fuel injection and ignition may be performed while the engine speed is sufficiently high. When the engine is started from the stopped state, the buffer device 12 may absorb the rotational deviation between the drive shaft 5 and the transmission 10. The cranking torque Tmg required for starting the engine from the stopped state is that when the engine inertia torque is Te, the first one-way clutch 17 is operated and outputs positive torque during cranking.
Tmg = Te / (1 + k) [Nm]
. Since the rotation speed of the motor generator 3 increases, the output necessary for starting does not change, but the cranking torque can be made smaller. Therefore, by using this drive device 1, the motor generator 3 can be reduced in size and efficiency.

(3) Immediately after starting the engine and after returning from the fuel injection cut This control is performed until the start of the engine 2 is completed and the engine rotation speed increases to reach the rotation speed of the motor generator 3. The same control is performed when the engine operation is resumed after the engine rotational speed is reduced due to the fuel injection cut at the time of deceleration.
FIG. 4 shows collinear charts immediately after engine startup and after fuel injection cut recovery. The engine 2 and the planetary carrier 21 are separated from the drive shaft 5 by power and are in an unloaded state. Therefore, engine rotational speed Ne increases rapidly until it reaches rotational speed Nmg of motor generator 3 + ring gear 22 and second one-way clutch 18 operates. At this time, at the moment when the second one-way clutch 18 is operated, a shock may occur in the drive shaft 5. Therefore, it is necessary to control the power generated by the motor generator 3 to reduce the shock. After Ne = Nmg and the second one-way clutch 18 is operated, the engine 2, the motor generator 3, and the drive shaft 5 are directly connected. Further, the planetary gear 16 rotates integrally to reduce loss.

(4) When the engine is running and when the vehicle is stopped This control is performed when it is necessary to charge the battery 14 or when the engine 2 needs to drive the auxiliary machine.
FIG. 5 shows an alignment chart when the engine is operating and when the vehicle is stopped. Also in this case, the rotational deviation between the drive shaft 5 and the transmission 10 is absorbed by the shock absorber 12. During engine operation, the second one-way clutch 18 is operated, and the engine 2, the motor generator 3, and the drive shaft 5 are directly connected to each other, so that all engine output is used for power generation. Therefore, the power generation amount can be controlled by increasing / decreasing the engine output as in the case of a conventional parallel hybrid vehicle.

(5) Starting and Acceleration When the transmission 10 starts and accelerates in the D range and R range, this control is performed.
FIG. 6 shows a nomographic chart at the time of starting and accelerating. Regardless of whether the transmission 10 is in the D range or the R range, torque is output from the drive shaft 5 only in the forward direction, and forward / reverse switching is performed by the transmission 10. Even in this state, since the second one-way clutch 18 operates, the engine 2, the motor generator 3, and the drive shaft 5 are directly connected as in the conventional parallel hybrid vehicle. Therefore, drive shaft torque Tout is equal to the sum of engine torque Te and torque Tmg by motor generator 3.
Tout = Te + Tmg [Nm]
In this case, if it is desired to assist the drive by the engine 2 by the motor generator 3, the torque Tmg of the motor generator 3 is set to Tmg> 0, and if it is desired to generate electric power by the motor generator 3, Tmg <0, and the corresponding torque is set to the engine torque. What is necessary is just to add to Te.
Further, at the time of starting, the driving torque is amplified by gradually engaging the shock absorber 12. Thereby, a smooth start is enabled.

(6) During deceleration This control is performed when the transmission 10 decelerates in the D range and R range.
FIG. 7 shows an alignment chart at the time of deceleration. At the time of deceleration, the engine 2 stops fuel injection (fuel injection cut), so that the rotational speed Ns of the sun gear 19 as well as the rotational speed Ne of the engine 2 + planetary carrier 21 rapidly decrease, and when Ns = 0, the second one way The clutch 18 is in an operating state.
Here, Ne1 is the engine speed during fuel injection cut, which is set when the driving device 1 is not used under the same vehicle conditions. When the drive device 1 is used, when the fuel is reinjected, the engine rotation speed increases to the rotation speed Nout of the drive shaft 5 (+ motor generator 3) + ring gear 22 without load as described in (3) above. Therefore, Nout = Ne1 can be set with a slight increase in the fuel injection amount, and the rotational speed Ne2 of the engine 2 + planetary carrier 21 when the fuel injection is cut can be set lower.
The rotational speed Nout of the drive shaft 5 (+ motor generator 3) + ring gear 22 when the second one-way clutch 18 is operating at the rotational speed Ns = 0 of the sun gear 19 is changed by the transmission 10 to Nout = Ne1 (engine speed). Speed), the rotational speed Ne2 of the engine 2 + planetary carrier 21 when the fuel injection is cut is as follows.
Ne2 = Nout / (1 + k) = Ne1 / (1 + k) [rpm]
The relationship between the friction torque Te from the engine 2 and the torque Tout exerted on the drive shaft 5 by the friction torque Te is as follows.
Tout = Te / (1 + k) [Nm] (i)

Here, a comparison is made of energy loss caused by engine friction during regeneration when the drive device 1 is used and when it is not used.
・ In the case of a conventional parallel hybrid vehicle:
If the rotational speed of the drive shaft 5 is equal to the rotational speed of the engine and the engine friction torque when the rotational speed of the engine is Ne1 is Te1, the loss energy P1 due to the engine friction is as follows.
P1 = Ne1 × Te1 × {2π / (60 × 1000)} [kw] (ii)
When this drive device 1 is used:
Assuming that the engine friction torque when the engine rotation speed is Ne2 is Te2, the torque Tout = Te2 / (1 + k) exerted by the engine friction torque on the drive shaft 5 from the equation (i), and Nout = Ne1. Therefore, the loss energy P2 due to engine friction is as follows.
P2 = Ne1 × {Te2 / (1 + k)} × {2π / (60 × 1000)} [kw] (......) (iii)
From (ii) and (iii) above,
P2 / P1 = Te2 / Te1 × (1 + k)} (iv)
Here, Te1> Te2 and k> 0. Therefore, from the equation (iv), by using this drive device 1, energy loss during regeneration due to drag of the engine 2 can be reduced, and the amount of regeneration by the motor generator 3 can be increased. As the value of k increases, the loss reduction ratio increases, but the amount of fuel required after returning from the fuel injection cut state also increases, so the value of k needs to be optimized.

(7) During idle stop This control is performed when the battery 15 is charged or when the engine 2 stops without driving the auxiliary machine.
FIG. 8 shows an alignment chart at the time of idling stop. When performing idling stop from the state (6), the engine 2 naturally stops due to the friction torque Te. However, in order to reduce the shock by shortening the time during which the engine rotation speed passes through the resonance region, the motor generator 3 is applied with the negative torque Tmg via the second one-way clutch 18 and the engine 2 is quickly stopped. .

  As described above, the drive device 1 of the hybrid vehicle can set the engine speed to be lower than the speed of the motor generator 3 when the engine 2 is stopped or is not generating torque due to fuel cut. The motor generator 3 can be directly connected in a state in which the torque is generated during the operation of the motor 2. The first one-way clutch 17 can also prevent reverse rotation of the engine 2. As a result, the hybrid vehicle drive device 1 reduces energy loss due to dragging of the engine 2, acts as a speed reducer when the engine 2 is started, and restricts reverse rotation of the engine 2. It is possible to prevent problems.

9 and 10 show a modification. In this modified example, portions that perform the same functions as those of the above-described embodiment will be described with the same reference numerals. As shown in FIG. 1, the power transmission mechanism 4 of the above-described embodiment connects the sun gear 19 of the planetary gear 16 to the device case 23 via the first one-way clutch 17, and connects the planetary carrier 21 to the output shaft 6 of the engine 2. , The motor generator 3 is connected to the ring gear 22, and the planetary carrier 21 and the ring gear 22 are mechanically connected via the second one-way clutch 18.
However, as shown in FIG. 9, the drive device 1 according to the modified example connects the sun gear 19 to the device case 23 by the sun gear-case connecting member 25 and interposes the first one-way clutch 17 to the planetary carrier 21. The planetary carrier 21 is connected to the output shaft 6 of the engine 2 via the first one-way clutch 17, and the planetary carrier 21 and the ring gear 22 are connected via the second one-way clutch 18.
The collinear diagram of this modification is the same except for the cases (3) and (5) of the previous embodiment. In (3) and (5) according to the modified examples, the first one-way clutch 17 rotates idly while the sun gear 19 is fixed at zero rotation, and only the engine rotation speed increases to the rotation speed of the ring gear 22, and the second one-way The clutch 18 is activated (see FIG. 10). As a result, a rotational deviation occurs between the gears 19, 20, and 22 of the planetary gear 16 during traveling, so that the loss during traveling increases compared to the case of FIG. 1.

  As described above, the drive device 1 according to the modified example can set the engine speed to be lower than the speed of the motor generator 3 when the engine 2 is stopped or is not generating torque due to fuel cut. Can be directly connected to the motor generator 3 in a state where the torque is being generated during operation. The first one-way clutch 17 can also prevent reverse rotation of the engine 2. As a result, the hybrid vehicle drive device 1 reduces energy loss due to dragging of the engine 2, acts as a speed reducer when the engine 2 is started, and restricts reverse rotation of the engine 2. It is possible to prevent problems.

  This invention reduces the energy loss due to the drag torque of the engine during motor running or fuel cut deceleration, acts as a speed reducer at the start of the engine, and restricts reverse rotation of the engine to cause problems such as poor lubrication This can be applied to a drive device for a parallel hybrid vehicle.

DESCRIPTION OF SYMBOLS 1 Drive device 2 Engine 3 Motor generator 4 Power transmission mechanism 5 Drive shaft 6 Output shaft 10 Transmission 12 Buffer device 14 Inverter 15 Battery 16 Planetary gear 17 First one-way clutch 18 Second one-way clutch 19 Sun gear 20 Planetary gear 21 Planetary carrier 22 Ring gear 23 Device case

Claims (2)

In a hybrid vehicle drive device that outputs power generated from an engine and a motor generator to a drive shaft via a power transmission mechanism,
The power transmission mechanism is
A planet comprising a first rotating element communicated with a fixed member via a first one-way clutch, a second rotating element communicated with at least the output shaft of the engine, and a third rotating element communicated with the motor generator Gears,
The first one-way clutch for preventing the rotation direction of the first rotation element from being opposite to the rotation direction of the engine;
A second one-way clutch provided between the second rotating element and the third rotating element and preventing the rotational speed of the second rotating element from becoming higher than the rotational speed of the third rotating element;
A hybrid vehicle drive device characterized in that when the engine is started, the first one-way clutch is operated to transmit the output of the motor generator to the engine via a planetary gear. In a hybrid vehicle drive device that outputs power generated from an engine and a motor generator to a drive shaft via a power transmission mechanism,
The power transmission mechanism is
A planetary structure comprising a first rotating element communicated with a fixed member, a second rotating element communicated with at least the output shaft of the engine via a first one-way clutch, and a third rotating element communicated with the motor generator. Gears,
The first one-way clutch for preventing the rotation direction of the first rotation element from being opposite to the rotation direction of the engine;
A second one-way clutch provided between the second rotating element and the third rotating element and preventing the rotational speed of the second rotating element from becoming higher than the rotational speed of the third rotating element;
A hybrid vehicle drive device characterized in that when the engine is started, the first one-way clutch is operated to transmit the output of the motor generator to the engine via a planetary gear.

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