KR100906871B1 - System and method for improving regenerative braking of hybrid electric vehicle - Google Patents

Abstract

The present invention relates to an apparatus and method for increasing regenerative braking of a hybrid vehicle, comprising a bypass flow passage for bypassing exhaust gas of an engine so as not to pass a catalyst, and developing a throttle valve during fuel cut during regenerative braking. By opening the bypass flow passage so that the exhaust gas of the engine is discharged through the bypass flow passage without passing through the catalyst, thereby reducing the engine suction pump loss and reducing the exhaust gas pressure, thereby reducing the friction loss of the engine. Finally, the present invention relates to an apparatus and method for increasing regenerative braking of a hybrid vehicle for increasing energy recovery in a regenerative braking section of a hybrid vehicle.

Hybrid Vehicle, Regenerative Braking, Engine Controller, Catalyst, Exhaust Gas, Bypass

Description

System and method for improving regenerative braking of hybrid electric vehicle

The present invention relates to an apparatus and method for increasing regenerative braking of a hybrid vehicle, and more particularly, by using an bypass apparatus for bypassing an electronically controlled throttle valve and exhaust gas without a catalyst in a regenerative braking section of a gasoline soft hybrid vehicle. The present invention relates to an apparatus and method for increasing regenerative braking of a hybrid vehicle to reduce a pump loss of an engine and to increase a recovery amount of regenerative braking energy.

In general, a hybrid vehicle in a broad sense means to drive a vehicle by efficiently combining two or more different power sources, but in most cases, an electric motor driven by an electric motor driven by an engine and a battery that uses a fuel to obtain driving power A vehicle that obtains driving power is referred to as a hybrid electric vehicle (HEV).

In response to the recent demand for improving fuel economy and developing more environmentally friendly products, research on hybrid vehicles is being actively conducted. In the case of commercial vehicles, hybrid buses and trucks are already commercialized and sold.

As is well known, in a hybrid vehicle, an electric motor (drive motor) provides the main or auxiliary power when the vehicle is driven, but the electric motor plays a role of recovering the kinetic energy of the vehicle as electric energy during vehicle deceleration and braking.

That is, a part of braking force is used for power generation during vehicle deceleration and braking, and electric energy generated at this time is stored in a battery, and a part of kinetic energy by driving speed is converted into energy required for driving a generator. To simultaneously reduce the kinetic energy (ie, reduce the speed of travel) and generate electrical energy.

This type of braking method is called regenerative braking, and the generation of electrical energy during regenerative braking can be achieved by reverse driving of a separate generator or drive motor.

Such regenerative braking can increase the mileage of the vehicle, and in particular, a hybrid vehicle equipped with a general internal combustion engine engine can achieve the purpose of improving fuel economy and reducing exhaust gas.

On the other hand, in a soft hybrid vehicle, it is impossible to block power transmission between the motor unit responsible for power generation and the engine generating friction loss during regenerative braking.

Therefore, there is a loss due to engine friction in recovering the inertial energy of the vehicle in the rotation braking section.

Currently, the gasoline engine has a fuel cut section to improve fuel efficiency in the above situation, wherein the throttle valve has a minimum opening amount during regenerative braking to prevent catalyst deterioration due to rapid oxidation of unburned hydrocarbons remaining in the catalyst. .

Accordingly, there is a problem in that the pump loss of the engine is sharply increased, and the regenerative braking amount is reduced due to the increased frictional loss of the engine.

As a conventional technique for reducing the friction loss of the engine in the regenerative braking section, the technology to reduce the friction loss by stopping the engine cylinder by stopping the intake valve in the regenerative braking section by remodeling the camshaft of the intake and exhaust valve of the engine has already been commercialized. However, this has a problem of increasing the manufacturing cost of the engine head portion.

Accordingly, the present invention has been invented in view of the above, and the pump loss of the engine using a bypass device that bypasses the electronically controlled throttle valve and the exhaust gas through the catalyst in the regenerative braking section of the gasoline soft hybrid vehicle. It is an object of the present invention to provide an apparatus and method for increasing a regenerative braking amount of a hybrid vehicle, which reduces the pressure and increases the amount of regenerative braking energy recovered.

In order to achieve the above object, the present invention, the bypass pipe is installed so as to connect the front end and the rear end of the catalyst in the exhaust pipe so that the exhaust gas flows through the catalyst in the hybrid vehicle; A flow path switching valve installed at the front end side of the catalyst where the bypass pipe is branched from the exhaust pipe to selectively open one of the catalyst inlet flow path and the bypass flow path passing through the bypass pipe; A sensor for detecting a bypass prohibition condition of exhaust gas; In the state of performing the fuel cut by receiving the regenerative braking entry signal from the vehicle controller, if it is determined whether the bypass prohibition condition of the exhaust gas corresponds to the bypass prohibition condition based on the signal of the sensor, and determines that it does not correspond to the bypass prohibition condition, A regenerative braking amount increasing device for a hybrid vehicle including an engine controller for switching a flow path switching valve to open the bypass flow path and then opening a throttle valve.

In another aspect, the present invention, the engine controller is applied to the regenerative braking start signal to perform a fuel cut; Determining, by the engine controller, whether the exhaust gas corresponds to the bypass prohibition condition based on a signal of a sensor for detecting the bypass prohibition condition of the exhaust gas; Subsequently, when it is determined that the bypass prohibition condition is not satisfied, the flow path switching valve is switched to operate so that the catalyst inlet flow path is blocked and the inlet end of the bypass pipe is opened so that the exhaust gas does not pass through the catalyst. Performing bypass of the exhaust gas to flow through the pipe; It provides a method of increasing the regenerative braking amount of a hybrid vehicle comprising the step of opening the throttle valve in the state that the bypass of the exhaust gas is performed.

According to the apparatus and method for increasing the regenerative braking amount for a hybrid vehicle of the present invention as described above, a bypass passage for bypassing the exhaust gas of the engine so as not to pass the catalyst is provided, and at the same time the throttle valve is developed during the fuel cut during regenerative braking. By opening the bypass passage so that the exhaust gas of the engine is discharged through the bypass passage without passing through the catalyst, it is possible to reduce the intake pump loss of the engine and to lower the exhaust gas pressure. The loss can be reduced, and the energy recovery can be effectively increased in the regenerative braking section of the hybrid vehicle.

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

The present invention relates to an apparatus and method for increasing regenerative braking of a soft hybrid vehicle, and using a bypass device that bypasses an electronically controlled throttle valve and exhaust gas without passing a catalyst in a regenerative braking section of a gasoline soft hybrid vehicle. To reduce the pump loss of the engine and to increase the recovery of regenerative braking energy.

In the present invention, in order to reduce the pump loss of the engine, an exhaust gas bypass flow path for bypassing the exhaust gas of the engine so as not to pass through the catalyst is configured, and the throttle valve is developed during the fuel cut during regenerative braking. In this case, the exhaust gas of the engine (which is pure air supplied by the throttle valve opening as described below) is discharged through the exhaust gas bypass flow path without passing through the catalyst to protect the catalyst, thereby reducing the intake pump loss of the engine. This leads to a reduction and lowering of exhaust gas pressure, thereby reducing the frictional losses of the engine and increasing the energy recovery in the regenerative braking section.

Hereinafter, the apparatus and method of the present invention will be described in more detail.

1 is a block diagram showing a regenerative braking amount increase for a hybrid vehicle according to the present invention, Figure 2 is a flow chart showing a regenerative braking amount increase method for a hybrid vehicle according to the present invention.

In FIG. 1, reference numeral 4 denotes a gasoline engine mounted in a gasoline soft hybrid vehicle, reference numeral 2 denotes an intake manifold of the engine, and reference numeral 3 denotes an injector for fuel injection of the engine.

Referring to FIG. 1, a vehicle controller (hereinafter referred to as HCU) 20 and an engine controller (hereinafter referred to as ECU) 30 are used in the present invention, and the HCU 20 is currently driven in a hybrid vehicle. The controller determines whether to enter the regenerative braking by determining the regenerative braking entry condition from the condition and the vehicle state information. When the regenerative braking entry condition is satisfied, the controller enters the regenerative braking mode and performs regenerative braking control.

For example, in a typical hybrid vehicle, the HCU 20 determines whether to enter regenerative braking based on an accelerator pedal signal, a brake pedal signal, a vehicle speed signal, a battery residual signal (SOC) signal, and the like. If all the regenerative braking entry conditions are satisfied by considering the vehicle speed and battery level, the regenerative braking entry and control is performed.

At this time, the HCU 20 applies and transmits an electrical signal indicating a regenerative braking entry to the ECU 30, that is, a Regen signal (or a fuel cut permission signal).

When the ECU 30 receives a signal during execution of the regenerative braking in the regenerative braking section from the HCU 20, that is, when the regenerative signal according to the regenerative braking mode is input from the HCU 20, the vehicle speed and the accelerator pedal opening amount are received. The fuel cut is determined according to the opening amount of the brake pedal, and when the fuel cut entry condition is satisfied, the fuel cut is stopped to stop the fuel injection of the injector 3.

Particularly, in the present invention, after the regenerative braking and the fuel cut are entered, the ECU 30 determines whether the bypass is performed by determining the exhaust gas bypass prohibition condition, but determines that the bypass is not the bypass prohibition condition. Take a pass.

That is, the ECU 30 opens a bypass flow path (bypass pipe) 12 which bypasses exhaust gas so as not to pass through the catalyst 9 to perform bypass of the exhaust gas. ) Acts as a bypass controller that controls the exhaust gas bypass device and is responsible for prohibiting the bypass of the exhaust gas, performing bypass, and releasing the bypass.

In addition, in the present invention, the ECU 30 determines that the exhaust gas bypass device operates to successfully enter the bypass of the exhaust gas, and at the same time, the exhaust gas bypass is normally entered and performed in the HCU 20. A signal, that is, a bypass entry success signal is applied and transmitted.

As such, the ECU 30 applies the bypass entry success signal to the HCU 20 in preparation for the engine friction torque which is rapidly decreased upon successful entry into the bypass.

In the present specification, the exhaust gas bypass is installed in the exhaust pipe 7 so that the exhaust gas (which becomes pure air discharged from the engine in the fuel cut state) from the engine in the regenerative braking and fuel cut entry state does not pass through the catalyst 9. It refers to a state that is bypassed through a separate bypass flow path (bypass pipe) 12 and discharged to the atmosphere.

In FIG. 1, reference numeral 1 denotes an electronically controlled throttle valve mounted on the intake side of the engine 4, which is configured to be controlled by the ECU 20. In the present invention, the ECU 20 includes regenerative braking. After successful fuel cut and exhaust gas bypass entry in the section, the throttle valve 1 is opened to reduce the engine intake pump loss regardless of the driver's accelerator pedal opening amount.

On the other hand, as a sensor for detecting the exhaust gas bypass prohibition condition, a signal of the oxygen sensor 6 for detecting the oxygen concentration of the exhaust gas is used immediately after the exhaust manifold, and in the present invention, the ECU 30 Upon receiving a signal from the oxygen sensor 6, it is confirmed that pure air without unburned hydrocarbon is discharged from the engine 4 as exhaust gas after the fuel cut and before entering the bypass.

Further, as a sensor for detecting whether the exhaust gas bypass has been successfully entered, a pressure sensor 8 for detecting the pressure of the exhaust gas is installed in the exhaust pipe 7 at the front end of the catalyst 9, and in the present invention, the ECU ( 30 determines whether the bypass entry is successful by determining whether the pressure is lowered due to the flow resistance of the catalyst carrier after the bypass entry by receiving a signal from the pressure sensor 8.

The exhaust pipe 7 is provided with a bypass pipe 12 which connects the catalyst front side and the rear end side so that the exhaust gas of the engine 4 flows bypasses the catalyst 9 without passing through the catalyst 9. In (7), a flow path switching valve 13 for selectively opening one of the catalyst inlet flow path and the bypass pipe 12 flow path is provided at the catalyst front end position where the bypass pipe 12 branches.

The flow path switching valve 13 is a valve operated under the control of the ECU 30. When the flow path of the catalyst inlet side of the catalyst 9 is closed, the inlet end of the bypass pipe 12 is opened. When the inlet end of the pass pipe 12 is closed, the catalyst inlet side flow path is opened.

In the present invention, the flow path switching valve 13 opens the inlet end of the bypass pipe 12 by the control signal output by the ECU 30 for bypass entry and execution, and shuts off the catalyst inlet side flow path, thereby exhausting. The gas (which is pure air) is only discharged (by-pass of the exhaust gas) through the bypass pipe 12.

Of course, when the bypass is released, the flow path switching valve 13 blocks the inlet end of the bypass pipe 12 under the control of the ECU 30 so that the exhaust gas is normally discharged through the catalyst 9 and the catalyst inlet flow path Will open.

Reference numeral 10 denotes a temperature sensor installed in the catalyst, which is also a sensor for detecting the bypass prohibition condition, and detects the catalyst temperature and applies it to the ECU 30.

In the present invention, before the bypass entry, that is, before the switching operation of the flow path switching valve 13, the ECU 30 compares the catalyst temperature detected by the temperature sensor 10 with the set temperature and the catalyst temperature is equal to or lower than the set temperature. Only when it is determined that the state is stable, the flow path switching valve 13 is operated to block the flow path of the catalyst inlet, and at the same time, the inlet end of the bypass pipe 12 is opened to bypass the exhaust gas.

At this time, when the catalyst temperature exceeds the set temperature, bypass of the exhaust gas is not performed.

In addition, in the present invention, the detection value of the temperature sensor 10 is used to prepare for an error occurrence of the bypass operation. The ECU 30 suddenly based on the signal of the temperature sensor 10 after outputting a control signal for bypass entry. Deterioration of the catalyst due to oxidation is detected.

That is, the ECU 30 receives a signal from the temperature sensor 10 to increase the catalyst temperature when the bypass fails, that is, the catalyst temperature due to the rapid oxidation of unburned hydrocarbons remaining in the catalyst 9. The rapid rise is determined, and upon detecting the rapid rise in temperature of the catalyst, the ECU 30 immediately controls the opening amount of the electronically controlled throttle valve 1 to the minimum amount.

Hereinafter, an operating state of the above-described regenerative braking amount increasing device will be described with reference to FIG. 2.

First, the HCU 20 determines whether to enter regenerative braking in consideration of vehicle speed, accelerator pedal opening amount, brake pedal opening amount, and battery SOC.

When the HCU 20 satisfies the predetermined regenerative braking entry condition, the HCU 20 enters the regenerative braking mode and applies a regenerative braking signal, ie, a regenerative signal, to the ECU 30 according to the regenerative braking operation, and applies the regenerative signal to the ECU 30. 30) first determines whether to cut the fuel according to the vehicle speed, the accelerator pedal opening amount and the brake pedal opening amount.

Here, when the ECU 30 determines that the predetermined fuel cut entry condition is satisfied, the ECU 30 maintains the minimum opening amount of the electronically controlled throttle valve 1 and stops the fuel injection of the injector 3, thereby preventing the bypass prohibition condition. The judgment is made to determine whether to enter the bypass.

At this time, pure fuel is discharged from the engine 4 as the fuel injection is stopped, and the ECU 30 measures the oxygen concentration in the exhaust gas in the regenerative braking and fuel cut state based on the signal of the oxygen sensor 6. By detecting the presence of unburned hydrocarbons, it is determined whether harmful substances are included in the exhaust gas.If the oxygen concentration in the exhaust gas is different from the preset oxygen concentration in the atmosphere by more than a predetermined level, the exhaust gas bypass device is not operated. The opening amount of the throttle valve 1 is kept at the minimum opening amount.

That is, the flow path switching valve 13 is maintained in a state of blocking the inlet end of the bypass pipe 12, and exhaust gas of the engine 4 is discharged to the atmosphere through the catalyst 9.

On the other hand, when the ECU 30 determines that the pure air is discharged from the engine 4 based on the signal of the oxygen sensor 6, the predetermined catalyst temperature detected by the temperature sensor 10 of the catalyst 9 is set. Compare with temperature.

At this time, when it is determined that the catalyst temperature is stable below the set temperature, the ECU 30 determines that all of the bypass entry conditions are satisfied, and drives the flow path switching valve 13 to open the inlet end of the bypass pipe 12. By opening, the exhaust manifold 5 and the bypass pipe 12 communicate with each other to bypass the exhaust gas.

Of course, when the catalyst temperature detected by the temperature sensor 10 exceeds the set temperature, the exhaust gas bypass device is not operated and the opening amount of the throttle valve 1 is maintained at the minimum opening amount.

After performing the bypass of the exhaust gas, the engine controller 30 determines whether the bypass has been successfully entered. The exhaust gas pressure detected by the pressure sensor 8 immediately after the exhaust manifold 5 is set to the set pressure. In comparison, when it is determined that the exhaust gas pressure detection value of the pressure sensor 8 decreases below the set pressure as the flow resistance by the catalyst carrier disappears, the bypass of the exhaust gas through the bypass pipe 12 is normally performed. It is judged that it is entering and performing.

In this way, when the ECU 30 determines the success of bypass entry, the electronically controlled throttle valve 1 is gradually opened to reduce the engine pump loss.

If the detected value of the pressure sensor 8 exceeds the set pressure, the ECU 30 determines that the bypass entry has failed. At this time, the ECU 30 immediately minimizes the electronic control throttle valve 1. While maintaining the opening amount, the bypass of the exhaust gas is stopped by closing the inlet end of the bypass pipe 12 by opening the flow path switching valve 13 to the initial position and opening the catalyst inlet side flow path.

In addition, the ECU 30 maintains the opening amount of the throttle valve 1 to the minimum opening amount even when the catalyst temperature detected by the temperature sensor 10 of the catalyst abnormally rises above the set temperature, Shut off the bypass (block the bypass pipe inlet).

In addition, the ECU 30 transmits a bypass entry success signal by applying a bypass entry success signal to the HCU 20 when determining that the bypass entry is successful, and a bypass entry failure signal when determining the bypass entry failure. Is applied to the HCU 20 to transmit a bypass entry failure state.

In addition, when the ECU 30 receives the regenerative braking end signal (or fuel cut release signal) from the HCU 20 during bypass of exhaust gas, the fuel throttle valve 1 is released in accordance with the current engine operating conditions. Opening amount control is performed, and the flow path switching valve 13 is driven to block the inlet end of the bypass pipe 7 and open the catalyst inlet side flow path to stop the bypass of the exhaust gas.

In this way, in the present invention, the pump loss of the engine can be reduced by bypassing the exhaust gas of the engine through the bypass pipe so as not to pass the catalyst during the fuel cut in the regenerative braking mode, and thus, the regenerative braking energy. It is possible to increase the recovery amount of.

1 is a configuration diagram of the regenerative braking amount increasing apparatus according to the present invention,

Figure 2 is a flow chart showing a method of increasing the regenerative braking amount according to the present invention.

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

1: electronically controlled throttle valve 2: intake manifold

3: injector 4: engine

5: exhaust manifold 6: oxygen sensor

7: exhaust pipe 8: pressure sensor

9 catalyst 10 temperature sensor

12: bypass pipe 13: flow path switching valve

Claims (8)

A bypass pipe installed to connect the catalyst front side and the rear end side of the exhaust pipe so that the exhaust gas can be bypassed without passing through the catalyst in the hybrid vehicle; A flow path switching valve installed at the front end side of the catalyst where the bypass pipe is branched from the exhaust pipe to selectively open one of the catalyst inlet flow path and the bypass flow path passing through the bypass pipe; A sensor for detecting a bypass prohibition condition of exhaust gas; In the state of performing the fuel cut by receiving the regenerative braking entry signal from the vehicle controller, if it is determined whether the bypass prohibition condition of the exhaust gas corresponds to the bypass prohibition condition based on the signal of the sensor, and determines that it does not correspond to the bypass prohibition condition, An engine controller for switching a flow path switching valve to open the bypass flow path, and then opening a throttle valve; Apparatus for increasing regenerative braking of a hybrid vehicle comprising a. The method according to claim 1, The sensor for detecting the bypass prohibition condition of the exhaust gas is an oxygen sensor for detecting the oxygen concentration in the exhaust gas provided immediately after the exhaust manifold, and a temperature sensor for detecting the catalyst temperature, In this case, the engine controller is configured to bypass the exhaust gas when the catalyst temperature detected by the temperature sensor exceeds a predetermined temperature while the oxygen concentration in the exhaust gas detected by the oxygen sensor is different from the atmospheric oxygen concentration by a predetermined level or more. A regenerative braking amount increasing device for a hybrid vehicle, characterized in that the passage is prohibited and the opening amount of the throttle valve is maintained at the minimum opening amount. The method according to claim 2, The engine controller controls the opening amount of the throttle valve to the minimum opening amount when the catalyst temperature detected by the temperature sensor exceeds a set temperature in a state in which the bypass flow path is opened and the throttle valve is opened. The regenerative braking amount increasing device of the hybrid vehicle, characterized in that for stopping the bypass of the exhaust gas by switching the operation of the flow path switching valve so as to open the catalyst inlet-side flow path. The method according to claim 1, It is provided in the exhaust pipe of the front end of the catalyst further comprises a pressure sensor for detecting the pressure of the exhaust gas, In this case, the engine controller increases the regenerative braking amount of the hybrid vehicle, characterized in that for opening the throttle valve when the pressure of the exhaust gas detected by the pressure sensor after the bypass flow path is less than the set pressure. An engine controller receiving a regenerative braking entry signal to perform a fuel cut; Determining, by the engine controller, whether the exhaust gas corresponds to the bypass prohibition condition based on a signal of a sensor for detecting the bypass prohibition condition of the exhaust gas; Subsequently, when it is determined that the bypass prohibition condition is not satisfied, the flow path switching valve is switched to operate so that the catalyst inlet flow path is blocked and the inlet end of the bypass pipe is opened so that the exhaust gas does not pass through the catalyst. Performing bypass of the exhaust gas to flow through the pipe; Opening the throttle valve in a state where bypass of exhaust gas is performed; How to increase the regenerative braking amount of a hybrid vehicle comprising a. The method according to claim 5, The sensor for detecting the bypass prohibition condition of the exhaust gas is an oxygen sensor for detecting the oxygen concentration in the exhaust gas provided immediately after the exhaust manifold, and a temperature sensor for detecting the catalyst temperature, At this time, the engine controller may be configured to bypass the exhaust gas when the oxygen concentration in the exhaust gas detected by the oxygen sensor is different from the oxygen concentration in the atmosphere by a predetermined level or more and the catalyst temperature detected by the temperature sensor exceeds a set temperature. A method for increasing the regenerative braking amount of a hybrid vehicle, characterized in that the passage is prohibited and the opening amount of the throttle valve is maintained at the minimum opening amount. The method according to claim 6, The engine controller controls the opening amount of the throttle valve to the minimum opening amount when the catalyst temperature detected by the temperature sensor exceeds the set temperature while the inlet end opening of the bypass pipe and the throttle valve are opened. A method of increasing the regenerative braking amount of a hybrid vehicle, wherein the bypass of the exhaust gas is stopped by switching the flow path switching valve to block an inlet end of the bypass pipe. The method according to claim 5, The engine controller opens the throttle valve when the pressure of the exhaust gas detected by the pressure sensor installed in the exhaust pipe at the front end of the catalyst becomes less than the set pressure while the exhaust gas is bypassed. How to increase regenerative braking amount of vehicle.

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