JP2020131866A - Torque assist device - Google Patents

Abstract

To provide a torque assist device in a vehicle that use an internal combustion engine as a drive source, with which start-up acceleration performance is improved by using an electric motor and it is possible to prevent the efficiency and durability of the power transmission system from decreasing due to the electric motor after the start.SOLUTION: It is equipped on a vehicle comprising an internal combustion engine 1, a transmission 4 connected to the internal combustion engine 1, and a differential mechanism 6 connected to the transmission 4 for distributing driving force to the left and right drive wheels. It comprises: an electric motor 8 that applies torque to an input gear 61 of the dynamic mechanism 6 to assist the torque; and a power connection/disconnection mechanism 9 arranged between an output shaft 81 of the electric motor 8 and the input gear 61, which transmits torque to the input gear 61 from the output shaft 81 under a travel start state of the vehicle and interrupts transmission of torque to the input gear 61 from the output shaft 81 when the travel start state is completed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a torque assist device suitable for use in a vehicle whose main drive source is an internal combustion engine.

When starting a vehicle driven by an internal combustion engine (hereinafter, also referred to as an engine), the driver may feel insufficient acceleration. This is because a large driving force is required when the vehicle starts, but the engine torque is also increasing while the engine speed is increasing as in the case of starting, so sufficient driving force cannot be obtained. to cause.

On the other hand, a technology for assisting the driving of the vehicle by an electric motor at the time of starting has been developed. For example, Patent Document 1 describes that a motor generator is connected to a transmission connected to an engine via a gear, and torque assist is performed by the motor generator for a short time at the time of starting.

Japanese Unexamined Patent Publication No. 2005-325804

As described above, the technique of torque assisting by the electric motor at the time of starting is effective in improving the feeling of acceleration at the time of starting, but as in Patent Document 1, the electric motor is always connected to the power transmission system. When the torque assist by the electric motor is completed and the torque of the electric motor becomes unnecessary, the motor that is carried around during traveling becomes an unnecessary engine load. For this reason, there is a risk that the fuel efficiency will be reduced due to the decrease in power transmission efficiency, and the durability of the power transmission system will be reduced due to heat generation due to the rotation of gears and the like connected to the electric motor.

The present invention was devised in view of such a problem. In a vehicle using an internal combustion engine as a drive source, an electric motor is used to improve start acceleration performance, and power transmission by the electric motor after start is achieved. It is an object of the present invention to provide a torque assist device capable of preventing a decrease in system efficiency and a decrease in durability.

The torque assist device of the present invention is installed in a vehicle including an internal combustion engine, a transmission connected to the internal combustion engine, and a differential mechanism connected to the transmission and distributing driving force to the left and right drive wheels. An electric motor that applies torque to the input gear of the differential mechanism to assist torque, and an electric motor provided between the output shaft of the electric motor and the input gear, and the vehicle starts from the output shaft in a starting state. A power disconnection mechanism that sets the torque transmission state to transmit the torque to the input gear and sets the torque transmission cutoff state to cut off the transmission of the torque from the output shaft to the input gear when the start start state is completed. It is characterized by having.

The start state is a state from the start of the start of the vehicle until the vehicle reaches a predetermined speed during acceleration, and the power disconnection mechanism is in the torque transmission state when the vehicle is stopped. It is preferable to switch to the torque transmission cutoff state when the speed of the vehicle is generated and reaches the predetermined speed.
The start state is a state from the start of the start of the vehicle to the elapse of a predetermined time for the acceleration of the vehicle, and the power disconnection mechanism is the state when the vehicle is stopped. It is preferable to switch to the torque transmission state and switch to the torque transmission cutoff state after a predetermined time elapses after the speed of the vehicle is generated.
It is preferable that the electric motor operates only in the starting state of starting to apply torque to the input gear.
It is preferable to provide an on / off switch for switching between an assist permitted state in which the torque assist by the electric motor can be performed and an assist prohibited state in which the torque assist cannot be performed by the electric motor.
A capacitor that supplies electric power to the electric motor and a charge control unit that charges the capacitor to a predetermined electric charge amount by the electric power of a power source mounted on the vehicle are provided, and the start start state of the predetermined electric charge amount is completed. It is preferable that the capacitor is set so as to be completely discharged in response to the above.
It is preferable that the electric motor and the capacitor have a 24V standard, and the power supply has a 12V standard.
The transmission is preferably a belt-type continuously variable transmission.
The electric motor is preferably a starter motor that also has the power disconnection / disconnection mechanism.

According to the present invention, when the vehicle starts, the torque is transmitted between the output shaft of the electric motor and the input gear of the differential mechanism. Therefore, the torque of the electric motor is transmitted to the input gear of the differential mechanism. The starting acceleration performance can be improved. When the start state is completed, the torque transmission is cut off between the output shaft of the electric motor and the input gear of the differential mechanism, so that the electric motor that has stopped operating is prevented from being carried around via the input gear. , It is possible to prevent a decrease in efficiency and durability of the power transmission system.

It is a block diagram which shows the drive system of the vehicle which concerns on one Embodiment. It is a schematic cross-sectional view of the transmission which shows the arrangement of each shaft in the transmission which concerns on one Embodiment. It is an acceleration characteristic diagram explaining the effect by the torque assist device which concerns on one Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments shown below are merely examples, and there is no intention of excluding the application of various modifications and techniques not specified in the following embodiments. Each configuration of the following embodiments can be variously modified and implemented without departing from the purpose thereof, and can be selected as necessary or combined as appropriate.

[Outline configuration of vehicle drive system]
As shown in FIG. 1, the vehicle according to the present embodiment includes an engine (internal combustion engine) 1 as a drive source. The output rotation of the engine 1 is determined via a torque converter with a lockup clutch 2, a gear train (drive counter gear, driven counter gear) 3, a transmission 4, a final reduction gear 5, and a differential mechanism 6 on the left and right drive wheels (not shown). It is distributed and transmitted to.

The transmission 4 includes a belt-type continuously variable transmission mechanism (simply referred to as a CVT) 20 and an auxiliary transmission mechanism 30, which are connected in series in a power transmission path from the engine 1 to the drive wheels (not shown). It is provided in.
The CVT 20 includes a primary pulley 21, a secondary pulley 22, and a V-belt 23 that is hung between these pulleys 21 and 22.
Although not shown in detail, the auxiliary transmission mechanism 30 is a transmission mechanism having two forward speeds and one reverse speed.

Further, as shown in FIGS. 1 and 2, the torque converter 2, the gear train 3, the transmission 4, the final reduction gear 5, and the differential mechanism 6 are provided in the transmission case 40. As shown in FIG. 2, the first axis (axis center O ₁ ) which is the input shaft of the torque converter 2 (the same axis as the rotation axis of the engine ₁ ) and the input shaft of the CVT 20 (the rotation axis of the primary pulley 21). The second axis (axis center O ₂ ), the third axis (axis center O ₃ ) which is the output shaft of the CVT 20 (rotation axis of the secondary pulley 22), and the fourth axis which is the output shaft (drive shaft) of the differential mechanism 6. (Axis center O ₄ ) is provided.

Further, an engine control unit (engine ECU) 1C for controlling the engine 1 is provided. The engine ECU 1C implements idling stop control that automatically stops the engine when all the conditions of brake on, accelerator off, and vehicle stop are satisfied, and restarts the engine when the brake is turned off after the automatic stop of the engine.

[Structure of torque assist device]
The drive system of the vehicle is equipped with a torque assist device 7 that assists the drive torque when the vehicle starts.
The torque assist device 7 is between the electric motor 8 that applies torque to the input gear 61 of the differential mechanism 6 with which the final reduction gear 5 meshes to assist the torque, and the output shaft 81 of the electric motor 8 and the input gear 61. It is configured to include a power disconnection / disconnection mechanism 9 interposed therein.

In the present embodiment, due to the arrangement relationship between the electric motor 8 and the input gear 61, the electric motor 8 uses the input gears via the gears 82, 83a, 83b, 84 as shown in FIGS. 1 and 2. It is connected to 61. The gear 82 is fixed to the fifth shaft 82S (axis center O ₅ ) and meshes with the input gear 61. The gear 83a is fixed to the sixth shaft 83S (axis center O ₆ ) and meshes with the gear 82. Sixth axis further gear 83b to 83S is fixed, the gear 83b will output shaft meshes with (seventh shaft) 81 a gear 84 which is fixed to the (axial center _{O 7)} of the electric motor 8. The gears 82, 83a, 83b, 84 align the rotation direction of the electric motor 8 with the rotation direction of the input gear 61, and reduce the rotation speed of the electric motor 8 to transmit the rotation speed to the input gear 61.

In this embodiment, a starter motor to which a power disconnection / disconnection mechanism is attached is used for the electric motor 8. Normally, the starter motor is equipped with a power disconnection mechanism that projects the pinion connected to the motor output shaft when the engine is started and connects it to the gear provided on the flywheel of the engine. When the vehicle is in the starting state, the gear 84 connected to the motor output shaft 81 is axially moved to be connected to the gear 83b and the electric motor 8 is operated.

Further, a capacitor 71 is provided to supply electric power to the electric motor 8.
Further, a torque assist control unit (torque assist ECU, control device) 100 for controlling the capacitor 71 and the electric motor 8 is provided according to the state of the vehicle.

The control device 100 includes a charge control unit 101 that charges the capacitor 71 from the power supply (power supply battery) 10 mounted on the vehicle to a predetermined storage amount when the engine is automatically stopped by idling stop control, and restarts the engine by idling stop control. After that, the motor control unit 102 that supplies the electric power of the capacitor 71 to the electric motor 8 when the on (or the idle switch is off) of the accelerator pedal is detected is provided.

Further, an on / off switch 110 for switching between an assist permitted state in which torque assist by the electric motor 8 can be performed and an assist prohibited state in which torque assist by the electric motor 8 cannot be performed is provided. Based on the setting of the on / off switch 110, the control device 100 performs torque assist control on the condition that the on / off switch 110 is set to on (torque assist can be performed).

Further, as the electric motor 8, a relatively high output 24-volt standard starter motor installed in a bus, a truck, or the like (so-called large vehicle) is used. Therefore, the capacitor 71 of the 24-volt standard is also applied.
On the other hand, the electrical equipment mounted on this vehicle is of the 12-volt standard installed in general passenger cars (so-called compact cars), and the power supply battery 10 is a 12-volt battery connected independently or in parallel. It has a 12-volt power supply.
Therefore, in this device, the voltage of the 12-volt battery is transformed to charge the 24-volt capacitor 71.

In the present embodiment, the starting state corresponds to the initial stage of starting in which the vehicle starts and accelerates after the vehicle starts starting in a state where there is no vehicle speed. Specifically, the period from the start of the vehicle start to the time when the vehicle reaches a predetermined speed (for example, 30 km / h) (starting from the rising speed of the vehicle and ending when the vehicle reaches the predetermined speed). ) Can be specified as the start state. In addition, a predetermined time (for example, 1.6 sec) elapses after the vehicle starts starting until a predetermined acceleration time (for example, 1.6 sec) elapses (starting from the rise of the vehicle speed). The period starting from the time when the vehicle is started) can be defined as the start state.

As described above, the start state starts from the start of the vehicle, but the torque assist by the electric motor 8 is desired to start without delaying the start of the vehicle. In the power disconnection mechanism 9 by the starter motor applied in the embodiment, when power is supplied to the electric motor 8 (starter motor), the gear 84 can be instantaneously projected and meshed with the gear 83b, so that the start is delayed. There is no such thing.
Further, when the starting state of the vehicle is completed, the control device 100 can switch the power disconnection / disconnection mechanism 9 to the torque transmission cutoff state by cutting off the power supply to the electric motor 8.

[Action and effect]
The torque assist device according to the present embodiment is configured as described above, and when the vehicle starts, the output torque of the electric motor 8 is applied to the input gear 61 of the differential mechanism 6. Therefore, as shown in FIG. , The starting acceleration performance of the vehicle is improved.
In FIG. 3, the broken line is the characteristic when the torque assist is not applied, and the solid line is the characteristic when the torque assist by the present torque assist device is applied.

When torque assist is not applied, the torque of the engine 1 increases in response to the increase in the rotational speed, so that sufficient engine torque is not generated while the rotational speed immediately after the start of the engine 1 increases. Further, while the rotation speed of the engine 1 is increasing, a part of the engine torque is consumed by the inertia of the power transmission system, so that the acceleration of the vehicle becomes slow. As a result, as shown by the broken line, the starting acceleration becomes slow and sufficient starting acceleration performance cannot be obtained.

On the other hand, when the torque assist by the torque assist device is applied, the electric motor 8 generates a large torque from the low speed rotation, so that the start acceleration becomes large and sufficient start acceleration performance can be obtained as shown by the solid line. Therefore, the start acceleration performance can be sufficiently improved by performing torque assist only for a limited short period from the start of the vehicle in the start state.

When the torque assist shown by the broken line is not applied, the maximum acceleration is larger than when the torque assist shown by the solid line is applied, but this is because the driver tries to obtain more acceleration due to insufficient starting acceleration. The acceleration was increased with a delay because the pedal was depressed deeper. On the other hand, when torque assist is applied, the starting acceleration can be sufficiently obtained, so that the driver's depression of the accelerator pedal can be suppressed. For this reason, when torque assist is applied, the maximum acceleration is lower as a result, but the lack of acceleration feeling is not felt, and more steps are taken to obtain a feeling of acceleration, depression is suppressed, and fuel consumption is reduced. Deterioration can also be suppressed.

Further, torque assist is performed only for a limited period of time, which is the start state, and when the start state is completed, the power disconnection / disconnection mechanism 9 is switched to the torque transmission cutoff state, so that the electric motor 8 that has stopped operating It is possible to prevent the power transmission system from being rotated by the input gear 61, and to prevent a decrease in efficiency and a decrease in durability of the power transmission system. Further, the electric motor 8 can be efficiently used for torque assist, and the power consumption by the electric motor 8 can be suppressed.

Further, in the present embodiment, since the CVT 20 is applied to the transmission, the engine torque is not efficiently transmitted as the vehicle driving force when the belt 23 slips, but in this device, the electric motor 8 is downstream from the CVT 20. Since the transmission is transmitted to the input gear 61 of the differential mechanism 6 of the above, torque assist can be performed without being affected by the slip of the belt 23, and the start acceleration performance can be reliably improved.

Further, since the in-vehicle device applies a starter motor having a voltage of 24V to the electric motor 8 for a vehicle having a voltage of 12V, it becomes easy to obtain a large output torque from the electric motor 8 and torque is used by using a large assist torque. Assist can be implemented, and the starting acceleration performance can be reliably improved. Since the existing popular starter motor can be applied to the 24V standard starter motor, the increase in equipment cost can be suppressed.

Further, since the capacitor 71, which is smaller and lighter than the battery and has a low cost, is used as the power source of the electric motor 8, it is easy to mount the electric motor 8 and the increase in the device cost can be suppressed.
In addition, when the engine is restarted from the time when the vehicle is automatically stopped by idling stop control and the vehicle is started, a feeling of sluggishness is likely to occur at the start and the start acceleration performance is likely to be insufficient. The feeling of sluggishness is avoided, and it becomes difficult to feel the lack of starting acceleration performance.
Of course, even when the vehicle is started when the engine 1 is idling and the vehicle is stopped, the torque assist can surely improve the starting acceleration performance.

[Other]
Although the embodiments have been described above, the present invention can be implemented by appropriately modifying the above embodiments without departing from the spirit of the present invention.
For example, in the above embodiment, the completion of the start state is determined from the speed of the vehicle after the vehicle starts and the elapsed time after the vehicle starts, and the operation stop of the electric motor 8 is controlled. By setting the amount of electric energy to be charged to 71 to a predetermined amount of electric energy so that the electric charge of the capacitor 71 is completely discharged corresponding to the completion of the start state, the operation stop of the electric motor 8 is not controlled. However, the electric motor 8 can be automatically stopped.

Further, in the present embodiment, a starter motor including a power disconnection / contact mechanism 9 is used as the electric motor 8, but a general electric motor can also be used. In this case, an electromagnetic clutch or the like may be interposed between the motor and the gear 84 so that the control device 100 controls the engagement and disengagement of the clutch.

Further, in the present embodiment, the vehicle using the CVT 20 for the transmission 4 has been described as an example, but the present device can also be applied to a vehicle using a stepped transmission.
Further, in the present embodiment, the electric motor 8 is connected to the input gear 61 via gears 82, 83a, 83b, 84, but if there is a degree of freedom in arrangement between the electric motor 8 and the input gear 61, it is electric. The motor 8 and the input gear 61 may be connected by one gear 82.

1 engine (internal combustion engine)
1C engine control unit (engine ECU)
2 Torque converter with lockup clutch 3 Gear train (drive counter gear, driven counter gear)
4 Transmission 5 Final deceleration device 6 Differential mechanism 7 Torque assist device 8 Electric motor 9 Power disconnection / disconnection mechanism 10 Power supply (power supply battery)
20 Belt type continuously variable transmission (CVT)
30 Sub-transmission mechanism 21 Primary pulley 22 Secondary pulley 23 V-belt 40 Transmission case 61 Input gear of differential mechanism 6 71 Capacitor 82, 83a, 83b, 84 Gear 100 Torque assist control unit (torque assist ECU, control device)
101 Charge control unit 102 Motor control unit 110 On / off switch

Claims (9)

It is installed in a vehicle equipped with an internal combustion engine, a transmission connected to the internal combustion engine, and a differential mechanism connected to the transmission and distributing driving force to the left and right drive wheels.
An electric motor that applies torque to the input gear of the differential mechanism to assist torque, and
It is provided between the output shaft of the electric motor and the input gear, and the starting state of the vehicle is a torque transmission state in which the torque is transmitted from the output shaft to the input gear, and when the starting state is completed. A torque assist device including a power disconnection mechanism for cutting off the transmission of the torque from the output shaft to the input gear to a torque transmission cutoff state. The start state is a state from the start of the start of the vehicle until the vehicle reaches a predetermined speed during acceleration.
The power disconnection mechanism according to claim 1, wherein the power disconnection mechanism switches to the torque transmission state when the vehicle is stopped, and switches to the torque transmission cutoff state when the vehicle speed is generated and reaches the predetermined speed. Torque assist device. The start state is a state from the start of the start of the vehicle to the lapse of a predetermined time for the acceleration of the vehicle.
The power disconnection mechanism according to claim 1, wherein the power disconnection mechanism switches to the torque transmission state when the vehicle is stopped, and switches to the torque transmission cutoff state when a predetermined time elapses after the speed of the vehicle is generated. Torque assist device. The torque assist device according to any one of claims 1 to 3, wherein the electric motor operates only in the starting state of starting to apply torque to the input gear. Claim 1 is provided with an on / off switch for switching between an assist permitted state in which the torque assist can be performed by the electric motor and an assist prohibited state in which the torque assist cannot be performed by the electric motor. The torque assist device according to any one of Items to 4. A capacitor that supplies electric power to the electric motor and a charge control unit that charges the capacitor to a predetermined storage amount by the electric power of a power source mounted on the vehicle are provided.
The predetermined storage amount is set according to any one of claims 1 to 5, wherein the charge of the capacitor is set so as to be completely released in response to the completion of the start start state. Torque assist device. The torque assist device according to claim 6, wherein the electric motor and the capacitor have a 24V standard, and the power supply has a 12V standard. The torque assist device according to any one of claims 1 to 7, wherein the transmission is a belt-type continuously variable transmission. The torque assist device according to any one of claims 1 to 8, wherein the electric motor is a starter motor that also has the power disconnection / disconnection mechanism.

Images