KR100986564B1 - power train of an hybrid electric vehicle and manipulating method thereof - Google Patents

Abstract

The present invention relates to a dual-mode powertrain for hybrid vehicles and a method of operating the hybrid vehicle. More specifically, the MG2 is selectively coupled to the output shaft or the second ring gear according to the vehicle speed by using two clutches, and the rotation speed of the MG1 is in the forward direction. (MG1 plays a generator role), MG2 is coupled to the output shaft to assist engine power with the motor, and if the rotation speed of MG1 is reverse (MG1 plays the motor role), the MG2 is separated from the output shaft. It is an object of the present invention to provide a dual mode power train for a hybrid vehicle and a method of operating the same, which can improve the efficiency of the system by preventing the reduction of power transmitted to the output shaft by coupling to the ring gear.

To this end, the present invention provides a planetary gear set including a first sun gear connected to a first motor-generator, a first ring gear connected to an engine, a carrier connected to a driving wheel, a second sun gear and a second ring gear; A brake installed to convert the second sun gear into a fixed state and a rotatable state; A first clutch installed to engage and separate between the first sun gear and the second sun gear; A second clutch provided to be coupled and detachable between the second motor-generator and the output shaft; And a third clutch provided to engage and disengage between the second ring gear and the second motor-generator.

Planetary Gear, Ring Gear, Carrier, Sun Gear, Dual Mode, Power Train, Motor-Generator, Clutch, Brake

Description

Power train of an hybrid electric vehicle and manipulating method

The present invention relates to a dual-mode powertrain for hybrid vehicles and a method of operating the hybrid vehicle. More specifically, the present invention relates to an electrically operated continuously variable transmission using a planetary gear and two motors, and adds a clutch to excessive motor speed. The present invention relates to a dual mode power train for a hybrid vehicle and a method of operating the same, which can be driven at a fixed speed ratio of an automatic transmission without using a motor when torque and output are required.

In general, the powertrain of the automatic transmission is a device for shifting the power generated by the engine in multiple stages using hydraulic pressure, etc. in order to obtain a proper torque according to the driving conditions.

The powertrain of the automatic transmission includes a planetary gear set that receives the power of the engine and changes the output to an appropriate rotational force, and a clutch or brake that fixes or rotates the rotational elements of the planetary gear set or rotates by the power of the engine. It consists of fastening elements such as.

The power train of the automatic transmission is the mainstream of the device that implements the 4th or 5th speed, but recently, a device capable of implementing the 6th speed as well as the 7th speed has been actively developed.

On the other hand, the conventional hybrid vehicle transmission is a system that controls the MG1 and MG2 by allowing two-speed motor-generator (hereinafter referred to as MG1, MG2) and the engine to the planetary gear to control the MG1 and MG2. .

A typical example is Toyota Prius. As shown in FIG. 1, MG1 is connected to a sun gear shaft, an engine is connected to a carrier shaft, and MG2 is connected to a ring gear shaft. In addition, it is configured to transmit power from the ring gear shaft to the drive shaft of the vehicle via the power transmission means.

The MG1 continuously adjusts the speed ratio by controlling the speed of the motor, and the MG2 assists engine power or recovers kinetic energy during regenerative braking, thereby enabling smooth on / off control of the engine without a separate clutch. And the regenerative braking efficiency can be improved by minimizing the friction brake.

However, in the method used in the Toyota Prius, as the vehicle speed increases, the speed of the MG1 is reversed from (+) to (-) by the lever diagram shown in FIG. 4, and energy recycling occurs and the amount of energy circulation increases. There is a problem that the efficiency is sharply lowered.

2 and 3 is a schematic diagram showing the flow of power according to the vehicle speed in the Prius of Toyota, Figure 2 shows the general power flow of MG1 and MG2 at low speed, Figure 3 is the flow of power of MG1 and MG2 at high speed This shows the reverse.

In the above-described power train structure, the planetary gear set receives power from the engine and branches the power of the engine to transfer a part of the engine power to the output shaft through the carrier and the ring gear, and transfers the other part of the engine power through the sun gear. To pass.

Here, the MG1 receives power from the engine and generates it as electric energy, and also supplies power generation energy to the electrically connected MG2. In addition, the MG2 is connected to the output shaft to replenish power of the engine and charge energy during regenerative braking. As such, it is common for MG1 to act as a generator and MG2 to act as a motor.

However, as shown in the lever diagram of FIG. 4, when the speed of the engine is constant, the speed of the MG1 changes from (+) → 0 → (−) as the speed (vehicle speed) of the output shaft increases. That is, when the speed of the vehicle increases, the moment occurs when the speed of MG1 becomes zero from (+). If the speed of the vehicle increases further, the speed of MG1 becomes (-) and the rotation direction (speed direction) of MG1 is reversed. do.

As such, when the rotation speed of MG1 is reversed, MG1 acting as a generator acts as a motor to generate power and transmits it to the planetary gear set, and MG2 absorbs some energy from the output shaft by MG2 connected to the output shaft. Energy recirculation occurs.

As described above, if the time at which the speed of MG1 becomes negative at a constant vehicle speed or longer continues, energy recycling of MG1 → sun gear → carrier → ring gear → MG2 → MG1 continuously occurs. That is, the MG1 receives electrical energy from MG2 and converts it into mechanical energy, and absorbs some of the mechanical energy delivered to the output shaft and converts it into electrical energy, thereby partially converting the mechanical energy delivered to the output shaft. Not only does it take away, but the conversion efficiency is lowered in the process of converting mechanical energy into electrical energy, and the overall system efficiency is drastically lowered.

The present invention has been made in view of the above, and when two clutches are used to selectively couple the MG2 to the output shaft or the second ring gear according to the vehicle speed, and the rotation speed of the MG1 is in the forward direction (MG1 acts as a generator). MG2 is coupled to the output shaft to assist the engine power with the motor, and when the rotational speed of MG1 is reverse (MG1 plays the role of the motor), the MG2 is separated from the output shaft and coupled to the second ring gear. The purpose of the present invention is to provide a dual mode powertrain for hybrid vehicles and a method of operating the same, which can improve the efficiency of the system by preventing the reduction of power transmitted through the system.

The above object is to provide a dual-mode powertrain for a hybrid vehicle,

A planetary gear set including a first sun gear connected to the first motor-generator, a first ring gear connected to the engine, a carrier connected to the drive wheel, a second sun gear and a second ring gear; A brake installed to convert the second sun gear into a fixed state and a rotatable state; A first clutch installed to engage and separate between the first sun gear and the second sun gear; A second clutch provided to be coupled and detachable between the second motor-generator and the output shaft; And a third clutch provided to engage and disengage between the second ring gear and the second motor-generator.

Preferably, the brake is characterized in that installed between the transmission case and the second sun gear of the planetary gear set.

The planetary gear set includes a plurality of stepped pinions, the stepped pinions each having a large diameter pinion engaged with the first sun gear and the first ring gear, and a small diameter pinion engaged with the second sun gear and the second ring gear. Characterized in that consisting of.

Another aspect of the present invention provides a method of controlling a dual mode powertrain for a hybrid vehicle,

In the dual mode, the second clutch is coupled and the third clutch is separated in the region where the speed ratio is high based on the time when the speed of the first motor-generator becomes zero (input branch mode), and the second clutch is in the region where the transmission ratio is low. Is achieved by a method of operating a dual mode powertrain for a hybrid vehicle, characterized by separating and coupling the third clutch (integrated branching mode).

Preferably, the second clutch is engaged as an EV mode, and the remaining brakes, first and third clutches are disconnected, the engine is stopped, and the first and second motor-generators are used for driving.

In the first stage mode, the brake is coupled, the remaining first to third clutches are separated, and the second sun gear is fixed to implement a fixed stage speed ratio.

In a two-stage mode, the first clutch is coupled, the remaining brakes, the second and third clutches are separated, and the first sun gear and the second sun gear are connected to implement a fixed stage speed ratio.

Accordingly, according to the dual-mode powertrain for hybrid vehicles according to the present invention and a method of operating the same, a dual-mode and stepped transmission ratio is realized by using a stepped pinion planetary gear set, three clutches, and one brake. Space can be saved and cost can be reduced.

In addition, it is possible to expect excellent performance in fuel economy and power performance by selecting and using two modes that can realize continuous speed ratio.

In addition, when the speed or torque of the motor is excessively increased or the power cycle occurs and the system efficiency is deteriorated, it is possible to drive using the step speed ratio so that the system performance can be improved and the performance required by the motor can be lowered.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

5 is a structural diagram of a dual mode power train for a hybrid vehicle according to an exemplary embodiment of the present invention.

The present invention relates to a dual-mode powertrain for a hybrid vehicle and a method of operating the same, wherein the second motor at the time when the first motor-generator 11 (hereinafter referred to as "MG1") is changed from (+) to (-) when the vehicle is running. -The generator 12 (hereinafter referred to as " MG2 ") is separated from the output shaft 19 with a clutch and attached to the second ring gear 18 so that the power transmitted to the output shaft 19 is transmitted to the MG2 12. The present invention relates to a dual mode powertrain for a hybrid vehicle and a method of operating the same, which can prevent the absorption of power transmitted to the output shaft and improve the system efficiency.

In addition, the present invention relates to a dual mode power train for a hybrid vehicle and a method of operating the same, which can realize a step speed ratio such as an automatic transmission by using a clutch when the MG1 (11) and the MG2 (12) are broken and cannot be used.

In general, a continuously variable transmission for a hybrid vehicle can be realized by using a planetary gear set 13 and two motor generators (representative example, Toyota Prius), and recently, a hybrid system of the Toyota Prius has been developed at high speed. In order to solve the problem, a dual mode hybrid system using an excellent mode among two modes according to driving conditions is being actively researched by combining two hybrid systems each having high efficiency at low speed and high speed. In other words, it operates as a dual-mode system that realizes a continuous speed ratio using a motor in normal driving conditions, but operates in a fixed speed ratio of an automatic transmission without using a motor when excessive speed, torque, or output is required for the motor. .

The configuration of the dual mode powertrain for a hybrid vehicle according to the present invention includes an engine 10, MG1 (11), MG2 (12), a set of stepped pinion planetary gears, a fastening element (clutch, brake (B)), and the like.

The engine 10 is connected to the first ring gear 14 to be described later, MG1 (11) is connected to the first sun gear 16 to be described later, to adjust the speed to implement a continuous speed ratio, the general driving situation It plays a role of generator, but it can act as a motor at a certain speed (high speed).

The MG2 12 may be connected to the output shaft 19 through the second ring gear 18 or the second clutch C2 through the third clutch C3, which will be described later. The engine 10 assists the power of the engine 10 in the hybrid mode supplied from the main power, and acts as a generator at a high speed at which the rotational speed of the MG1 11 is reversed (−).

One set of stepped pinion planetary gears is composed of a ring gear, a pinion, a sun gear, and a carrier 15 like the general planetary gear set 13, but further includes one ring gear and one sun gear. That is, the first sun gear 16 and the first ring gear 14, the second sun gear 17 and the second ring gear 18 use the pinion and the carrier 15 in common.

Here, the pinion has a stepped cross section in the upper and lower portions, each pinion is a large diameter pinion, the second ring gear 18 and the second sun gear (10) meshed with the first ring gear 14 and the first sun gear 16. It consists of a small diameter pinion meshed with 17), the large diameter pinion and the small diameter pinion are rotatably formed integrally. The carrier 15 connects the respective pinions and is connected to the drive wheels 20 to transmit power of the engine 10 to the drive wheels 20.

The fastening element includes a clutch and a brake (B) for connecting and disconnecting or stopping rotation of a rotating element such as a motor, a planetary gear set (13), an output shaft (19), and more specifically, a transmission with a brake (B). A brake B installed between the case 21 (hereinafter referred to as a "case") and the second sun gear 17, and a clutch provided between the first sun gear 16 and the second sun gear 17 by a clutch. The first clutch C1, the second clutch C2 provided between the MG2 12 and the output shaft 19, and the third clutch C3 provided between the second ring gear 18 and the MG2 12 are included. do.

In this case, the clutch connects and disconnects the rotating elements by coupling and separating the two friction members from each other, and the brake B is connected to and detaches the rotating elements from the two friction members. (21)) to stop the rotation by connecting and disconnecting.

When the brake B is coupled, the second sun gear 17 is fixed, and when the first clutch C1 is engaged, the first sun gear 16 and the second sun gear 17 are coupled to each other.

The second clutch C2 and the third clutch C3 are selectively coupled to implement a dual mode (input branch mode, integrated branch mode), and combine the second clutch C2 in the input branch mode, and When the clutch C3 is detached, the MG2 12 is connected to the output shaft 19 to assist the engine 10 power. In the integrated branch mode, the second clutch C2 is disconnected and the third clutch C3 is coupled. MG2 12 is separated from output shaft 19 and MG1 11 assists in engine 10 power.

The operation method of the dual mode power train for a hybrid vehicle according to the operation mode of the present invention by such a configuration is as follows.

FIG. 6 is a power train structure diagram of the EV mode and the input branch mode in FIG. 5, FIG. 7 is a power train structure diagram of the integrated branch mode in FIG. 5, FIG. 8 is a power train structure diagram of the first stage mode in FIG. 5, and FIG. 9. 5 is a power train structure diagram of the two-stage mode in Figure 5, Figure 10 is a clutch analysis table in FIG.

The operation mode according to the present invention includes an EV mode, an input branch mode, an integrated branch mode using a motor, and a first stage, two stage and a three stage mode having a fixed speed ratio like an automatic transmission without using a motor. At this time, the EV mode is a mode for driving using only the motor, the input branch mode and the integrated branch mode is a hybrid mode using all the power of the engine 10 and the MG2 (12), in particular the input branch mode is the MG1 (11) This mode is operated at low speed and high speed ratio with the rotation speed of (+) direction, and integrated branch mode is mode at high speed and low speed ratio with (-) direction of the rotation speed of MG1 (11).

1) EV mode

The EV mode is structurally the same as the input branch mode. This mode is realized by engaging the second clutch C2 and separating the remaining fastening elements, that is, the first clutch C1, the third clutch C3, and the brake B. The sun gear 17, the carrier 15, and the second ring gear 18 act as a simple reducer and increase the torque of the MG2 12 to transmit it to the output shaft 19. In this mode, the MG1 11 only serves to control the speed of the engine 10 and the MG2 12 actually drives the vehicle.

In this mode, the fuel is not supplied to the engine 10 because the vehicle runs only by the motor. In this situation, the engine 10 is controlled to stop by the MG1 11 because the engine 10 may act as a load when the engine 10 rotates. In addition, this mode has the same principle and structure as the regenerative braking situation. In the EV mode, the MG2 12 generates power and transmits the power to the vehicle, but in the regenerative braking situation, the kinetic energy is transmitted from the vehicle to the MG2 12. There is a difference.

2) Input-split mode

The input branch mode refers to a mode in which one motor (eg, MG2 12) is directly connected to the output shaft 19 without passing through a power branch device (eg, a planetary gear).

The input branch mode is implemented in the present invention by coupling the second clutch C2 and separating the remaining fastening elements, that is, the first clutch C1, the third clutch C3, and the brake B, and the second clutch C2. ), The second sun gear 17, the carrier 15, the second ring gear 18 acts as a simple reducer, and the MG2 12 is directly connected to the output shaft 19 without passing through the power diverter.

Looking at the power flow in the input branch mode, when power is input from the engine 10 to the first ring gear 14, the power is branched by the planetary gear, a part of the engine 10 power is the first ring gear 14 ), The carrier 15 → the output shaft 19 → the driving wheel 20, and the other part of the engine 10 power is transmitted to the first ring gear 14 → the carrier 15 → MG1 (11).

At this time, the MG1 (11) acts as a generator to convert the mechanical energy of the engine 10 power into electrical energy and then transferred to the electrically connected MG1 (11), MG2 (12) acts as a motor to the MG1 (11) Receives electric energy transmitted from the power transmission to the output shaft 19 through the second clutch (C2).

However, when the vehicle speed increases and the rotational speed of the MG1 11 is reversed, the MG1 11 acts as a motor to transfer the power from the first sun gear 16 to the carrier 15 to the output shaft 19 and to the MG2. 12 acts as a generator to generate the electric power transmitted from the output shaft 19 through the second clutch C2 to electric energy and transfer it to the MG1 11. In such a case, part of the power continues to circulate, leading to a decrease in power transmission efficiency (similar to the conventional problem described above).

In order to solve this problem, the present invention provides a vehicle with low speed (high speed ratio) to medium speed or high speed (low speed ratio), that is, rotation speed of MG1 (11) from (+) (forward direction) to (-) (reverse direction). Changes from input branch mode to integrated branch mode at the point of change.

3) Integrated Branch Mode

The compound branch mode is implemented in the present invention by combining the third clutch C3 and separating the remaining fastening elements, that is, the first clutch C1, the second clutch C2, and the brake B, and the second clutch C2. ), The MG2 (12) is separated from the output shaft (19).

When the vehicle speed is increased and the rotation speed of the MG1 11 is reversed, the power flow is examined in the multi-branch mode. The power is input from the engine 10 to the first ring gear 14, and the MG1 11 is a motor. By acting to transmit power to the first sun gear 16, the power of the MG1 11 together with the engine 10 power is integrated via the carrier 15 and then transmitted to the output shaft 19.

At this time, the MG2 12 acts as a generator and receives power from the carrier 15 through the second ring gear 18 to convert mechanical energy into electrical energy and transfer it to the MG1 11.

Therefore, when the second clutch C2 is separated and the third clutch C3 is coupled, the MG2 12 is separated from the output shaft 19 so that even if the rotation directions of the MG1 11 and the MG2 12 are changed, the engine ( 10) Power is transmitted to the drive wheel 20 through the output shaft 19 without being taken away by the MG2 (12).

4) 1st mode

As a mode having a fixed speed ratio, in the present invention, the brake B is coupled and the remaining fastening elements, that is, the first to third clutches C1 to C3 are separated, and the brake B is coupled to the second sun gear 17. ) Is fixed so that a fixed speed ratio (1 step) of a fixed size is realized.

5) 2 speed mode

A mode having a fixed speed ratio is implemented in the present invention by engaging the first clutch (C1) and separating the remaining fastening elements, that is, the second and third clutch (C3) and the brake (B), the second clutch (C2) When coupled, the first sun gear 16 and the second sun gear 17 are coupled to each other so that the first sun gear 16, the second sun gear 17, the carrier 15, the first ring gear 14 and the second ring gear ( 18) becomes a horizontal line by the lever diagram, and the fixed gear ratio is fixed to one.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to these embodiments, and has been claimed by those of ordinary skill in the art to which the invention pertains. It includes all the various forms of embodiments that can be carried out without departing from the spirit.

1 is a powertrain structure diagram of a conventional Toyota Prius,

FIG. 2 is a diagram showing a power branch structure at a low speed (when the speed direction of MG1 is a forward direction) in FIG. 1;

3 is a diagram of a power branch structure at high speed (when the speed direction of MG1 is reverse direction) in FIG. 1;

4 is a lever diagram according to the vehicle speed;

5 is a structural diagram of a dual mode powertrain for a hybrid vehicle according to an embodiment of the present invention;

6 is a power train structure diagram of the EV mode and the input branch mode in FIG.

FIG. 7 is a diagram illustrating a powertrain structure of the integrated branch mode in FIG. 5;

FIG. 8 is a power train structure diagram of the single stage mode in FIG. 5;

9 is a power train structure diagram of the two-stage mode in FIG.

10 is a clutch analysis table in FIG.

<Description of the symbols for the main parts of the drawings>

10 engine 11: first motor-generator

12: 2nd motor-generator 13: stepped pinion planetary gear set

14: first ring gear 15: carrier

16; First sun gear 17; 2nd Sun Gear

18: second ring gear 19: output shaft

20: drive wheel 21: transmission case

B: Brake C1: First Clutch

C2: Second Clutch C3: Third Clutch

Claims (7)

In a dual mode powertrain for a hybrid vehicle, A first sun gear 16 connected to the first motor-generator 11, a first ring gear 14 connected to the engine 10, a carrier 15 connected to the drive wheel 20, and a second sun gear 17. And a planetary gear set 13 having a second ring gear 18; A brake (B) installed to switch the second sun gear (17) to a fixed state and a rotatable state; A first clutch (C1) installed to engage and separate between the first sun gear (16) and the second sun gear (17); A second clutch C2 provided to be coupled to and detachable from the second motor-generator 12 and the output shaft 19; And And a third clutch (C3) installed to be coupled and detachable between the second ring gear (18) and the second motor-generator (12). The method according to claim 1, The brake (B) is a hybrid mode dual-mode powertrain, characterized in that installed between the transmission case 21 and the second sun gear (17) of the planetary gear set (13). The method according to claim 1, The planetary gear set 13 includes a plurality of stepped pinions, the stepped pinions each having a large diameter pinion engaged with the first sun gear 16 and the first ring gear 14, and the second sun gear 17. And a small diameter pinion meshed with the second ring gear (18). In the method of controlling the powertrain of claim 1, Based on the time when the speed of the first motor-generator 11 becomes zero, the second clutch C2 is coupled and the third clutch C3 is separated in the region where the speed ratio is high, and in the region where the speed ratio is low, A method of operating a dual mode power train for a hybrid vehicle, characterized by separating the two clutches (C2) and engaging the third clutch (C3). The method according to claim 4, The second clutch C2 is coupled and the remaining brakes B, the first and third clutches C1 and C3 are separated, the engine 10 is stopped, and the first and second motor-generators A method of operating a dual mode power train for a hybrid vehicle, characterized by traveling using 11, 12). The method according to claim 4, Combining the brake (B) and separating the remaining first to third clutch (C1 ~ C3), and fixing the second sun gear 17 to implement a fixed stage speed ratio for a hybrid vehicle, characterized in that How does it work? The method according to claim 4, The first clutch C1 is coupled, and the remaining brakes B, the second and third clutch C3 are separated, and the first sun gear 16 and the second sun gear 17 are connected to each other to achieve a fixed gear ratio. A method of operating a dual mode power train for a hybrid vehicle, characterized in that the implementation.

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