CN103726934B - A kind of throttled-wide method of controlling exhaust gas of hybrid vehicle - Google Patents

Abstract

The invention belongs to the technical field of automobiles, and in particular relates to an exhaust control method for fully opening a throttle valve of a hybrid electric vehicle. The control process is as follows: firstly, an exhaust bypass branch connected to the exhaust main road is set on the catalytic converter of the engine throttle, and then the exhaust bypass branch is opened after the engine cuts off the fuel and the throttle is fully opened for a certain period of time. Close the exhaust bypass branch when the engine starts to output power after the engine fuel cut-off throttle exits the fully open state, so as to prevent the exhaust gas from being discharged through the exhaust bypass branch without passing through the catalyst. The invention can effectively solve the problems of reduced catalytic conversion efficiency and increased NOx emission caused by the catalytic converter caused by a large amount of fresh air entering the catalytic converter after the throttle valve is fully opened.

Description

A method for exhaust control of hybrid electric vehicles with fully open throttle

technical field

The invention belongs to the technical field of automobiles, and in particular relates to an exhaust control method for fully opening a throttle valve of a hybrid electric vehicle.

Background technique

The hybrid electric vehicle combines the engine, the motor, and the energy storage device (battery, etc.), and the good matching and optimal control between them can give full play to the advantages of the internal combustion engine vehicle and the electric vehicle and avoid their respective shortcomings. Low-emission and low-fuel-consumption vehicles of practical development significance. When the engine is running at low load, the output torque provided by its fuel consumption is used to overcome the pumping loss. If the pumping loss can be reduced or even eliminated, the fuel consumption of the engine will also be greatly reduced. The pumping loss of the engine can effectively reduce the braking force of the engine, and the engine oil cut-off and full throttle technology is usually used to reduce the pumping loss. However, after adopting the technology of engine oil cut-off and full throttle opening, more fresh air is pressed into the three-way catalytic converter. Excessive fresh air in the three-way catalytic converter will not only reduce the temperature of the catalytic converter and weaken the catalytic conversion efficiency, but also A large amount of fresh air entering the three-way catalytic converter will also create a high temperature and oxygen-enriched reaction condition, which will cause a large amount of nitrogen to be converted into nitrogen oxides, which will cause serious environmental pollution after being discharged into the air.

Contents of the invention

The object of the present invention is to provide a method for controlling the exhaust of a hybrid electric vehicle with the throttle fully open in order to solve the above-mentioned shortcomings in the background technology.

The technical scheme adopted in the present invention is: a kind of exhaust control method of the throttle valve of hybrid electric vehicle fully open, comprises the following steps:

(1) An exhaust bypass branch connected to the main exhaust road is provided on the catalytic converter of the engine throttle, and a control valve is arranged on the exhaust bypass branch;

(2) Open the exhaust bypass branch after the engine fuel-cut throttle is fully opened for a certain period of time, so that part of the fresh air flows through the exhaust bypass branch instead of completely passing through the main exhaust road equipped with catalyst;

(3) Close the exhaust bypass branch when the engine starts to output power after the engine fuel cut-off throttle exits the fully open state, so as to prevent the exhaust gas from being discharged through the exhaust bypass branch without passing through the catalyst.

Further, the pipe diameter of the exhaust bypass branch in the step (1) is 1/2-3/4 of the pipe diameter of the main exhaust road.

Furthermore, in the step (2), the interval time between the full opening of the engine fuel cut-off throttle and the opening of the exhaust bypass branch is 0.3-1s.

The control method of the present invention can make a large amount of fresh air flowing in after the throttle valve is fully opened not completely pass through the main road equipped with a catalyst, so as to ensure that the catalytic conversion efficiency will not be reduced due to a large amount of air lowering the temperature of the catalytic converter, and at the same time because there is no A large amount of fresh air flows into the main road, and only the high temperature environment of the catalyst cannot produce more NOx, effectively reducing NOx emissions. The method is simple and effective, and can reduce environmental pollution while not reducing the conversion efficiency of the catalytic converter.

Description of drawings

Fig. 1 is a schematic diagram of the temperature change of the catalyst during the NEDC cycle process of the present invention.

Fig. 2 is a schematic diagram of the exhaust control of the throttle valve in the normal working state of the present invention.

Fig. 3 is a schematic diagram of the exhaust control in the state of the throttle valve fully opened according to the present invention.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments to facilitate a clear understanding of the present invention, but they do not limit the present invention.

The three-way catalytic converter is the most important external purification device installed in the automobile exhaust system. It can convert harmful gases such as CO, HC and NOx emitted from automobile exhaust into harmless carbon dioxide, water and nitrogen through oxidation and reduction. , so that the car exhaust can be purified. The three-way catalyst should react at a minimum temperature of 350°C. When the temperature is too low, the conversion efficiency will drop sharply; while the catalyst’s active temperature (best working temperature) is about 400°C to 800°C, if it is too high, it will also cause the catalyst to age. exacerbated. As shown in Figure 1, the temperature inside the three-way catalytic converter with full-throttle valve technology is significantly higher than that without full-throttle valve technology. At this time, a large amount of fresh air will enter the three-way catalytic converter, resulting in a The high-temperature oxygen-enriched reaction conditions promote the conversion of nitrogen into nitrogen oxides in large quantities, resulting in the generation of NOx.

As shown in Figure 2 and Figure 3, to solve the problem that a large amount of fresh air enters the catalytic converter after the throttle valve is fully opened and causes the catalytic conversion efficiency of the catalytic converter to decrease and the NOx discharge to increase, the method steps adopted by the present invention are:

(1) Set an exhaust bypass branch connected to the main exhaust road on the catalytic converter of the engine throttle, set a control valve on the exhaust bypass branch, and realize exhaust bypass by closing and opening the control valve Closing and opening of branches. The size of the pipe diameter of the exhaust bypass branch needs to meet the purpose of exhausting the fresh air that enters from the branch when the engine fuel cut-off throttle is fully opened, so the size of the branch pipe depends on the size and direction of the main pipe diameter And arrangement, in this embodiment, the branch pipe diameter of the exhaust bypass branch is 1/2-3/4 of the pipe diameter of the main exhaust road.

(2) The above-mentioned exhaust bypass branch is only opened after a certain delay time after the engine fuel cut-off throttle is fully opened, so that not only can the fresh air flow through the exhaust bypass branch but not completely pass through the catalyst. Exhaust main road, and can ensure that the flow of exhaust bypass branch is fresh air instead of exhaust gas generated by combustion in the engine. Part of the fresh air flows through the exhaust bypass branch, which can weaken the cooling effect of the fresh air on the catalytic converter to a certain extent. At the same time, because there is not a large amount of fresh air flowing into the main exhaust road, only high temperature environment cannot produce more NOx, reducing environmental pollution.

The interval time between the full opening of the engine fuel-cut throttle and the opening of the exhaust bypass branch must ensure that the residual exhaust gas is completely exhausted from the conversion of the three-way catalyst when the engine is switched from the working state to the fully open fuel-cut throttle, that is, the interval time Depending on the discharge speed of the exhaust gas, it should be as small as possible under the premise of ensuring that the exhaust gas is completely discharged along the main exhaust road. The delay time used in this embodiment is 0.3-1s.

(3) Close the exhaust bypass branch when the engine starts to output power after the engine fuel cut-off throttle exits the fully open state, so as to prevent the exhaust gas from being discharged through the exhaust bypass branch without passing through the catalyst.

The content not described in detail in this specification belongs to the prior art known to those skilled in the art.

Claims (2)

1. the throttled-wide method of controlling exhaust gas of hybrid vehicle, it is characterised in that comprise the following steps:

(1), an exhaust bypass branch road connected with exhaust main main line is set on the catalyst converter of engine air throttle, described exhaust bypass branch road arranges control valve；The branch road caliber of exhaust bypass branch road is sized to the 1/2-3/4 of exhaust main main line caliber；

(2), after electromotor oil-break WOT certain time, open exhaust bypass branch road, make fresh air component flow through from exhaust bypass branch road and not exclusively pass through the exhaust main main line equipped with catalyst；

(3), exit closedown when full-gear rear engine starts power output at electromotor oil-break air throttle and lead to exhaust bypass branch road, it is to avoid tail gas will pass through logical exhaust bypass branch road without catalyst and discharges.

2. a kind of throttled-wide method of controlling exhaust gas of hybrid vehicle according to claim 1, it is characterised in that: in described step (2) electromotor oil-break WOT and exhaust bypass branch road open between interval time be 0.3-1s.