KR102370924B1 - Hybrid Electric Vehicle for Sequential Start type Engine Cold Start - Google Patents

Abstract

The sequential start method engine cold start method of the hybrid vehicle according to the present invention is the operation of the starter 9 when the engine cold start condition is determined by the detection of the engine speed and the coolant temperature of the controller 10 according to the start of the engine 2 . MHSG added to the starter 9 by completing the start of the engine 2 by the operation of the MHSG 7 following the stop of the starter 9 at a specific engine speed of the engine 2 or more after the engine 2 is started The engine startability is improved by applying the cranking torque of (7), and in particular, the cranking torque of the MHSG is linked with the timing at which the engine crank and the auxiliary belt system overcome engine friction to rotate. Along with weakening the belt slip of the accessory system 4 applied to the engine 2 , the impact and noise of the accessory tensioner are also weakened.

Description

Hybrid Electric Vehicle for Sequential Start type Engine Cold Start

The present invention relates to a hybrid vehicle to which engine cold start control is applied, and more particularly, to a hybrid vehicle to which a sequential engine cold start control is applied in which the engine is cold started by cooperative control of a starter and a Mild Hybrid Starter & Generator (MHSG). .

In general, a mild hybrid electric vehicle among hybrid electric vehicles is a MHSG system of a MHSG (Mild Hybrid Starter & Generator), a 48V battery and an LDC (Low Voltage DC/DC Converter) along with a gasoline/diesel engine. (normally, 48V MHSG system) is applied.

Therefore, a mild hybrid vehicle that connects a small displacement engine and an MHSG system can further improve fuel efficiency and reduce CO2 significantly.

In particular, the mild hybrid vehicle starts the engine by MHSG cranking through the MHSG system. As a result, power loss and noise generation due to excessive slip of the auxiliary belt, which is developed due to a decrease in the durability of the auxiliary belt during MHSG cranking under cold start conditions, is prevented.

Korean Patent Publication No. 10-2010-0063308 (June 11, 2010)

However, starting the engine under cold start conditions by a starter (eg, a conventional starter) may result in deterioration of startability due to an increase in MHSG inertial.

In particular, the two-way tensioner applied to the mild hybrid vehicle applied with the MHSG system is a pendulum-type double arm auxiliary tensioner, which is due to the fact that the relative motion of the belt and the tensioner develops into shock and noise when an abrupt change in angular velocity such as a start-up occurs.

Accordingly, the present invention in consideration of the above points improves engine startability by applying the cranking torque of the MHSG at a predetermined engine speed or more after the starter is cranked during cold start of the engine, and in particular, the cranking torque of the MHSG increases the engine The crank and auxiliary belt system overcomes engine friction and is linked with the timing to rotate, thereby weakening the auxiliary belt slip and reducing the impact and noise of the auxiliary tensioner. An object of the present invention is to provide a hybrid vehicle that implements the present invention.

The engine cold start method of the present invention for achieving the above object is a sequential MHSG engine start control to which the cooperative control between the starter and the MHSG is applied when the engine cold start condition according to the engine speed and the coolant temperature is determined by the controller. It is characterized in that the engine cold start is made.

In a preferred embodiment, the sequential MHSG engine start control eliminates the effect of engine friction on the engine by the accessory system.

In a preferred embodiment, the engine speed and the coolant temperature are detected when the engine is started.

In a preferred embodiment, the sequential MHSG engine start control includes the steps of (A) determining the engine speed and the coolant temperature as the engine cold start condition, and (B) operating the starter under the engine cold start condition. A step of starting the engine, (C) the operation of the MHSG is performed after the operation of the starter, and the step of completing the starting of the engine is performed.

In a preferred embodiment, the starting of the engine by the starter is confirmed by starter engine cranking of the engine.

As a preferred embodiment, the engine speed of the engine is detected before the operation of the MHSG, and whether or not the MHSG operates is determined based on the engine speed by detecting the engine speed. The engine speed for operating the MHSG is greater than or equal to a set value. When the operation of the MHSG is made, the operation of the starter is stopped.

In a preferred embodiment, when the engine speed and the coolant temperature are not suitable for the engine cold start condition, the engine is started by MHSG engine start control, and the MHSG engine start control is performed by the MHSG alone. Controlled.

In a preferred embodiment, the failure of the engine cold start condition includes an ISG (Idle Stop & GO) ON/OFF operation of the engine.

And the hybrid vehicle of the present invention for achieving the above object includes an engine; In the case of engine cold start condition determined by the detection of the engine speed and coolant temperature of the controller according to the engine starting, the engine is started by the starter operation, and then the starter stops at a specific engine speed or more. a controller that completes the starting of the engine; characterized in that it is included.

In a preferred embodiment, the MHSG constitutes a 48V MHSG system together with a 48V battery and LDC.

As a preferred embodiment, the controller includes a starting torque map, and the starting torque map is constructed as data of the engine cranking of the starter and the engine cranking of the MHSG when the engine is cold started. The controller includes an input unit that processes the engine speed and the coolant temperature detected by the vehicle-mounted sensor as input data, a cold start output unit that outputs the cold start condition signal based on the engine speed and the coolant temperature, It includes a cold start control unit that detects the engine rotation speed of the engine while controlling the starter with a starting condition output signal, and a MHSG control unit that controls the MHSG under the condition of a specific engine rotation speed of the engine.

The hybrid vehicle of the present invention implements the following actions and effects by implementing the sequential start method engine cold start control.

First, compared to engine cold starting, which was performed only with the starter in mild hybrid vehicles, the decrease in startability due to increased MHSG inertia is prevented. Second, it does not develop into a decrease in the durability of the accessory belt by reducing the power loss and noise generation due to excessive belt slippage compared to the engine cold start when the MHSG was not available. Third, the relative motion between the belt and the tensioner caused by a sudden change in the angular velocity of the accessory system during cold engine start is weakened, thereby greatly weakening the impact and noise generation of the pendulum-type double arm accessory tensioner. Fourth, the marketability of mild hybrid vehicles to which the 48V MHSG system is applied is greatly improved by improving engine cold startability and reducing the impact and noise of auxiliary belts.

1 is a flowchart of a method for cold starting a sequential start engine according to the present invention, FIG. 2 is an example of a mild hybrid vehicle to which a sequential start engine cold start control according to the present invention is applied, and FIG. 3 is a controller according to the present invention It is a configuration diagram, and FIG. 4 is an example of an engine starting profile diagram through an experiment exemplifying the effect of the sequential starting method engine cold start control according to the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying illustrative drawings, and since these embodiments are examples, those of ordinary skill in the art to which the present invention pertains may be implemented in various different forms. It is not limited to the embodiment.

1, the engine cold start method is divided into sequential MHSG engine start (S30 to S80) and MHSG engine start (S90) based on engine cold start condition determination (S20) from detected engine state information (S10). Engine start completion (S100) is made.

Therefore, the cold start method is a logic capable of improving startability and reducing noise by starting the hybrid engine by sequentially using the starter and the MHSG. In particular, the cold start method reduces the slip of the accessory belt in the process of improving engine startability, thereby resolving the shock and noise phenomenon that may occur in the tensioner of the accessory during the engine cold start of the 48V mild hybrid vehicle.

Referring to FIG. 2 , the vehicle 1 includes an engine 2 , an auxiliary system 3 , a vehicle-mounted sensor 4 , a Mild Hybrid Starter & Generator (MHSG) 7 , a starter 9 , and a controller 10 ) is included.

Specifically, the engine 2 is an internal combustion engine and generates power for the vehicle 1 together with a motor (not shown). The auxiliary system 3 is composed of a pulley and a belt connected to the pulley, and draws out the crankshaft rotational force of the engine 2 to the outside. The vehicle-mounted sensor 4 transmits engine-related detection data including engine revolutions per minute and coolant temperature to the controller 10 . The MHSG 7 forms a 48V MHSG system together with a 48V battery and an LDC (Low Voltage DC/DC Converter), and starts the engine 2 by MHSG cranking. The starter 9 starts the engine 2 by starter cranking.

Therefore, the vehicle 1 is a hybrid vehicle including an engine 2 and a motor (not shown) as power generating means, and is a mild hybrid vehicle in which the engine is started by the MHSG 7 together with the starter 9 .

Specifically, the controller 10 controls the MHSG 7 using engine friction of the accessory system 3 as a control factor to limit the starting torque map based on engine cranking of the starter 9 during cold start. ) by MHSG cranking to start the engine (2). To this end, the controller 10 includes a starting torque map 10-1, and the starting torque map 10-1 is an engine friction control factor for each pulley and belt of the auxiliary system 3 and a starter 9 and matching data for each engine cranking of the MHSG 7 . For example, the matching data applies the MHSG cranking torque, engine speed, and accessory belt slip when the engine 2 is cold-started.

Referring to FIG. 3 , the controller 10 includes logic or hardware as components, and is divided into an input unit 11 , a cold start output unit 13 , a cold start control unit 15 , and an MHSG control unit 17 . .

Hereinafter, the sequential start method of FIG. 1 will be described in detail with reference to FIGS. 2 to 4 . In this case, the controlling subject is the controller 10 associated with the cold start map 10 - 1 , and the controlling subject is the MHSG 7 and the starter 9 .

When the start of the engine 2 is detected (eg, the ignition is ON), the controller 10 determines the engine cold start condition of S20 through the detection of the engine state information of S10 .

2 and 3 , the controller 10 processes the engine rotation speed and coolant temperature detected by the vehicle-mounted sensor 4 through the input unit 11 as input data. Then, the cold start output unit 13 separates the MHSG engine starting torque and the MHSG engine starting torque sequentially at a specific engine revolution number while checking the cold starting condition of the engine 2 with a specific coolant temperature. In this case, the distinction between the sequential MHSG engine starting torque and the MHSG engine starting torque is made because the ISG (Idle Stop & GO) ON/OFF operation of the engine 2 is considered, and if the engine rotation speed processed as input data When the and coolant temperature are the detected values after the engine 2 is completely stopped, the MHSG engine starting torque signal may not be generated because it is an engine cold start condition. For example, the specific coolant temperature may be about 60° C. or less and the specific engine rotation speed may be applied to less than about 10 RPM, but this specific value is set differently depending on the type of vehicle 1 .

As a result, the controller 10 generates a starting torque signal for sequential MHSG engine start under the engine cold start condition, and controls the MHSG 7 and the starter 9 with sequential MHSG engine start, respectively.

The controller 10 sequentially starts the MHSG engine by detecting the starting torque map data in S30, starting the starter engine in S40, and starting the MHSG engine according to S50 to S80.

2 and 3 , the controller 10 sequentially controls the MHSG engine starting torque through the cold start control unit 15 . The cold start control unit 15 receives the sequential MHSG engine starting torque signal from the cold start output unit 13 in the starting torque map data detection step of S30, and outputs the signal to the starter 9 in the starter engine starting step of S40. to operate the starter (9). As a result, the engine 2 is cold-started through the starter 9 .

Then, the controller 10 performs the MHSG engine starting in the engine cranking detection step S50, the engine rotation speed determination step S60, the MHSG cranking torque calculation step S70, the starter stop and the MHSG driving step S80. In this case, the following equation is applied to the step of determining the engine speed of S60.

MHSG engine speed judgment formula: engine speed > A

Here, "engine rotation speed" is the engine rotation speed detected by the vehicle-mounted sensor 4 following the cold start of the engine 2, and "A" is set to about 10 RPM as the set engine rotation speed.

2 and 3 , the cold start output unit 13 of the controller 10 is a vehicle-mounted sensor 4 inputted from the cold start output unit 13 to the input unit 11 in the engine cranking detection step of S50. ) detects engine cranking at the engine speed of , and the cold start control unit 15 uses the detected engine speed after starter cranking of the engine 2 to determine the specific engine speed in the engine speed determination step of S60. Compare with 10 RPM. Next, if the specific engine speed is 10 RPM or more in the engine speed determination step of S60, the MHSG cranking torque calculation step of S70 calculates the engine cranking torque of the MHSG 7 for the engine speed of 100 RPM or more, and then the MHSG control unit 17 to output the MHSG driving signal. Then, the MHSG control unit 17 of the controller 10 operates the MHSG 7 with the MHSG driving signal in the starter stop and MHSG driving steps of S80.

As a result, the engine 2 is started according to the engine cold start condition with the engine cranking torque of the starter 9 and the engine cranking torque of the MHSG 7 following it.

Then, the controller 10 terminates the sequential MHSG engine start in the engine start completion step of S00, and then controls the engine 2 through the subsequent engine control logic.

On the other hand, the MHSG engine start of S90 is the start of the engine 2 by the MHSG engine starting torque signal in the engine cold start condition determination of S20, which is the engine 2 by the MHSG 7 without the intervention of the starter 9. means start. In this case, the ISG (Idle Stop & GO) ON/OFF operation of the engine 2 is applied as an unsuitable condition for engine cold starting, so that the MHSG engine start is applied when the ISG is turned on after the ISG OFF of the engine 2 is performed.

On the other hand, referring to FIG. 4 , from the difference between the engine starting profile of the MHSG 7 and the engine starting profile of the starter 9 , the engine starting using the MHSG 7 quickly passes through a fluctuation section due to the initial explosion of the engine. is exemplified As a result, the engine starting profile shows that, compared to the engine cold start of the starter 9 alone, the engine cold start by the linkage of the starter 9 and the MHSG 7 starts with the rapid entry into the idle area along with the improvement of the cold start performance of the engine 2 . It is also proven that the time is shortened and, in particular, the stability of the accessory belt of the accessory system 4 is greatly improved according to the cold start.

As described above, in the sequential start method engine cold start method of the hybrid vehicle according to the present embodiment, when the engine cold start condition is determined by the detection of the engine speed and the coolant temperature of the controller 10 according to the start of the engine 2 , After the engine 2 is started by the operation of the starter 9, the start of the engine 2 is completed by the operation of the MHSG 7 following the stop of the starter 9 at a specific engine speed of the engine 2 Engine startability is improved by applying the cranking torque of the MHSG 7 in addition to the starter 9. In particular, the cranking torque of the MHSG increases the engine friction between the engine crank and the auxiliary belt system. The impact and noise of the accessory tensioner are also weakened along with weakening of the belt slip of the accessory system 4 applied to the engine 2 by being associated with the timing of winning and turning.

1: vehicle 2: engine
3: Auxiliary system 4: Vehicle-mounted sensor
7: MHSG (Mild Hybrid Starter & Generator)
9: starter 10: controller
10-1: starting torque map 11: input part
13: cold start output unit 15: cold start control unit
17: MHSG control unit

Claims (14)

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In the case of engine cold start condition determined by the detection of engine speed and coolant temperature according to engine starting, the engine is started by the starter operation, and then the engine is started by the MHSG operation following the starter stop at a specific engine speed or higher. A controller that completes the engine cold start; is included;
The controller includes a starting torque map, and each output value of engine cranking of the starter and engine cranking of the MHSG is constructed as data in the starting torque map when the engine is cold started hybrid vehicle.
The hybrid vehicle of claim 11 , wherein the MHSG constitutes a 48V MHSG system together with a 48V battery and a Low Voltage DC/DC Converter (LDC).
The method according to claim 11, wherein the controller performs cooperative control of the starter and the MHSG when the engine is cold starting in order to eliminate the effect of engine friction caused by the auxiliary system at the engine rotation speed and the coolant temperature detected when the engine is started, Using the engine speed and the coolant temperature as engine cold start conditions, after starting the engine of the starter, the MHSG operation is determined based on the engine speed detected in the engine start confirmation state by starter engine cranking, and the engine speed greater than or equal to the set value The hybrid vehicle, characterized in that the MHSG is driven together with the starter stop in the MHSG, and the engine control is performed by the MHSG alone control when the determined cold start condition including the ISG ON/OFF operation is not satisfied.
The method according to claim 11, wherein the controller includes an input unit, a cold start output unit, a cold start control unit, and an MHSG control unit;
The input unit processes the engine speed and the coolant temperature detected by the vehicle-mounted sensor as input data, and the cold start output unit outputs a cold start condition signal based on the engine speed and the coolant temperature. The hybrid vehicle according to claim 1, wherein the start control unit detects the engine speed of the engine while controlling the starter with the cold start condition output signal, and the MHSG control unit controls the MHSG under the condition of a specific engine speed of the engine.

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