KR20160104240A

KR20160104240A - Throttle control method for a hybrid electric vehicle

Info

Publication number: KR20160104240A
Application number: KR1020150026979A
Authority: KR
Inventors: 용진우
Original assignee: 현대자동차주식회사
Priority date: 2015-02-26
Filing date: 2015-02-26
Publication date: 2016-09-05

Abstract

The present invention includes a step of developing a throttle when an engine start signal is requested from an HCU (Hybrid Control Unit) 10 at the time of starting a hybrid vehicle, and increasing the engine speed by slipping the engine clutch; Comparing engine speeds corresponding to preset ignition speeds; Comparing a throttle opening degree corresponding to a target opening degree of a predetermined throttle when an engine speed reaches an ignition speed or more; And the throttle opening degree of the throttle opening is kept equal to the target opening degree to terminate the starting by igniting the fuel injection and the ignition. By providing the throttle control method of the hybrid vehicle, the throttle is expanded to reduce the pumping loss, The torque required for starting the engine can be reduced to reduce the specification of the driving motor. Therefore, it is expected that the material cost can be reduced by manufacturing the driving motor.

Description

[0001] The present invention relates to a throttle control method for a hybrid vehicle,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a throttle control method of a hybrid vehicle capable of reducing a pumping loss at engine starting of a hybrid vehicle, thereby reducing an engine startup torque and consequently reducing a specification of a drive motor.

BACKGROUND ART Generally, an eco-friendly automobile includes hybrid electric vehicles, fuel cell vehicles, electric vehicles, plug-in electric vehicles and includes at least one motor and an engine, a battery for driving the motor, an inverter for converting the DC voltage of the battery into an AC voltage, An HSG (Hybrid Starter Generator) that performs engine startup and power generation, and an engine clutch that is mounted between the engine and the motor to provide EV mode or HEV mode.

This eco-friendly car combines the engine and the motor with the EV mode, which provides acceleration by the operation of only the motor according to the conditions of the acceleration / deceleration depending on the operation of the accelerator pedal and the brake pedal, the gradient of the road, Thereby providing an HEV mode that provides driving to the region where the efficiency of the engine and the motor is the best.

That is, according to the engine torque, engine speed, and motor torque arm measurement graph according to the throttle control shown in FIG. 1, the TMED hybrid vehicle has an engine clutch for connecting the engine and the motor, It is necessary to start the engine and slip the engine clutch so that the power of the engine can be supplied to the transmission. The specification of the driving motor is largely determined by the maximum driving torque in the EV mode and the engine starting torque required at that time do.

Meanwhile, in the case of the conventional internal combustion engine vehicle, a proposal (US-0867061, 2007-10-04) for improving the combustion stability and the exhaust characteristic by controlling the throttle at the engine startup, a proposal for solving the stability problem (JP- 0013297, 2002-01-22), but it is not proposed to control the throttle to reduce the starting torque of the hybrid vehicle.

Therefore, it is required to reduce the starting torque of the engine in order to reduce the specification of the driving motor in the 'HSG elimination TMED hybrid system' in which the starting time is long and the torque required for starting the engine greatly affects the specification of the driving motor.

In order to solve the above problems, the present invention provides a method of reducing pumping loss by adjusting a wide open throttle (WOT) TMED (Transmission Mounted Electric Device) in a HSG elimination TMED hybrid system vehicle, A throttle control method for a hybrid vehicle in which a throttle is adjusted to a load according to a speed to reduce a torque required for starting the engine.

According to an aspect of the present invention, there is provided a method of controlling an engine, the method comprising: expanding a throttle when an engine start signal is requested from an HCU (Hybrid Control Unit) and slipping the engine clutch to increase the engine speed; Comparing engine speeds corresponding to preset ignition speeds; Comparing a throttle opening degree corresponding to a target opening degree of a predetermined throttle when an engine speed reaches an ignition speed or more; And terminating the starting of the hybrid vehicle by keeping the throttle opening degree equal to the target opening degree and performing fuel injection and ignition.

If the throttle opening degree with respect to the target opening degree is not equal to the target opening degree, the throttle opening degree adjusting means may further comprise adjusting the throttle opening degree to match the load so as to maintain the combustion stability of the engine.

By providing the present invention with the above-described configuration, the throttle is expanded to reduce the pumping loss, and the throttle is adjusted to the load according to the engine speed, so that the torque required for starting the engine can be reduced, It is expected that the material cost can be reduced by manufacturing the drive motor.

1 is a graph showing engine torque, engine speed, and motor torque value according to conventional throttle control.
2 is a flowchart of a throttle control method according to the present invention.
3 is a graph showing engine torque, engine speed, and motor torque value measurement through the throttle control method according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains.

It is very important to reduce the engine starting torque in the case of a vehicle with the 'HSG elimination TMED hybrid system' which carries both the running of the vehicle and the starting of the engine with the driving motor in the process of switching from the EV mode to the HEV mode while the hybrid vehicle is running Do.

That is, the specification of the drive motor is determined by the maximum drive torque in the EV mode, and the engine start torque required at this time.

Accordingly, when the starting torque is reduced, the specification of the driving motor can be reduced accordingly, so that the manufacturing cost of the driving motor can be reduced as well as the weight of the vehicle can be reduced.

According to the purpose, according to the object of the present invention, when the engine start signal is requested from the HCU 10 as shown in the flowchart of the throttle control method shown in FIG. 2, the throttle is expanded and the engine speed is increased by slipping the engine clutch. (S10)

Here, when the driver depresses the accelerator pedal, the HCU 10 determines the driver's acceleration will and maintains the developed state when the engine start signal is sent to the throttle.

At this time, it is preferable that the slip start timing of the engine clutch is made equal to the throttle start timing together with the engine start signal generation timing of the HCU 10.

On the other hand, when the difference (slip speed) between the rotational speed of the motor measured through the crank angle sensor 30 and the rotational speed of the engine slipping through the engine clutch is within a predetermined speed (50 rpm) to be.

That is, when the slip speed is 50 rpm or less, the slip of the engine clutch is terminated.

Next, the engine speed is compared with the ignition speed preset in the ECU 20 during the rotation of the engine through the above-described step S10.

At this time, the ignition speed means an engine rpm capable of ignition of the engine, and the ignition speed is set in the ECU 20. When the engine speed reaches the ignition speed, the ignition proceeds.

Generally, in order to be able to ignite the engine, the speed of the engine must exceed a certain level, and the ignition speed is determined to be at a level of 500 rpm or more, and this value may vary depending on driving conditions such as the type of engine,

When the engine speed reaches the ignition speed or more, the throttle opening degree measured by the throttle position sensor 40 is compared with the target opening degree of the preset throttle. (S30)

Therefore, the throttle opening degree can be adjusted to maintain the optimum engine ignition state.

Finally, the throttle opening degree is kept the same as the target opening degree, and the fuel injection and ignition are performed to terminate the startup. (S40)

Through these steps, the hybrid vehicle can be switched from the EV mode to the HEV mode and driven by the engine.

On the other hand, when the throttle opening degree with respect to the target opening degree is not the same, the throttle opening degree is adjusted in accordance with the load so as to maintain the combustion stability of the engine. (S50)

This is because the combustion may be unstable when the throttle is opened and started. Therefore, after the engine speed exceeds the ignition speed, the throttle developed for combustion stability must be readjusted and fuel injection and ignition must be performed.

That is, the developed throttle is adjusted to the target opening degree according to the type of the engine and the running condition for the combustion stability.

According to the graph of the engine torque, engine speed, and motor torque value measured through the throttle control method shown in FIG. 3, the present invention can be applied to a hybrid vehicle in which the throttle is opened (WOT) And when the engine speed reaches a predetermined ignition speed or more, the throttle opening degree is re-adjusted to the load to ignite, thereby reducing the torque required for starting the engine.

In other words, since the throttle is expanded to reduce the pumping loss and the throttle is adjusted to the load according to the engine speed, the torque required for starting the engine can be reduced to reduce the specification of the driving motor. A reduction effect can be expected.

The terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary terms. It should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Therefore, the configurations shown in the drawings and the embodiments described herein are merely the most preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention. Therefore, It should be understood that various equivalents and modifications are possible.

10: HCU
20: ECU
30: Crank angle sensor
40: throttle position sensor
S10: Throttle deployment and engine speed increase step
S20: Engine speed comparison step
S30: Throttle opening degree comparison step
S40: Fuel injection and ignition phase
S50: Throttle opening adjustment step

Claims

When the engine start signal is requested from the HCU 10, the throttle is developed and the engine speed is increased by slipping the engine clutch (S10);
Comparing the engine speed corresponding to the preset ignition speed (S20);
A step (S30) of comparing the throttle opening degree corresponding to the target opening degree of the throttle preset when the engine speed reaches the ignition speed;
(S40) of finishing starting by keeping fuel injection and ignition while keeping the throttle opening degree the same as the target opening degree.

The method according to claim 1,
Further comprising the step (S50) of adjusting the throttle opening to a load so as to maintain the combustion stability of the engine when the throttle opening degree to the target opening degree is not the same.