DE102012002239A1 - Thermal regulation of a hybrid vehicle using a bypass path in a catalytic converter unit - Google Patents

Abstract

A hybrid vehicle has an exhaust treatment system that has a bypass valve for directing an air flow or exhaust gas through a bypass path or through a primary catalyst. The hybrid vehicle has an internal combustion engine and an electric motor, each of which can be selectively put into operation with a transmission in order to provide a drive torque. The electric motor rotates the internal combustion engine when it is in the operating state in order to provide the drive torque, as a result of which a flow of unheated air is generated from the internal combustion engine, which air flows through the exhaust gas treatment system. The bypass valve directs the flow of air through the bypass path when the engine is rotating and not receiving fuel to prevent the primary catalyst from cooling. The bypass valve directs the flow of exhaust gas through the primary catalyst when the internal combustion engine is rotating and being supplied with fuel, i. H. runs to treat the flow of exhaust gas.

Description

TECHNICAL AREA

The invention relates generally to a hybrid vehicle and method of operating the hybrid vehicle to maintain the thermal efficiency of a catalytic converter of an exhaust treatment system for an internal combustion engine when the engine is rotated but not fueled.

BACKGROUND

Hybrid internal combustion engine (ICE) engines include an exhaust treatment system for reducing exhaust gas toxicity from the engine. The treatment system typically includes a catalytic converter unit having a catalyst that reduces nitrogen oxides in the exhaust gas to nitrogen and carbon dioxide or water, as well as oxidizes carbon monoxide (CO) and non-combusted hydrocarbons (HCs) into carbon dioxide and water. The catalyst may include, but is not limited to, platinum group metals (PGM). The catalyst must be heated to a light-off temperature of the catalyst before the catalyst becomes operable. Accordingly, the exhaust gas must heat the catalyst to the light-off temperature before the reaction between the catalyst and the exhaust gas begins.

The hybrid vehicle may further include an electric motor. The internal combustion engine and the electric motor may each be selectively operated to drive the vehicle, i. H. each of the internal combustion engine and the electric motor may be selectively operated to generate a drive torque for a transmission. When the electric motor is in operation to provide the drive torque to the transmission, the internal combustion engine is typically not fueled and does not run. However, since both the electric motor and the internal combustion engine are coupled to the transmission to provide the drive torque to the transmission, the electric motor may cause the internal combustion engine to rotate when the electric motor is operating to provide the drive torque. When the internal combustion engine is rotated while the electric motor provides the drive torque, the internal combustion engine generates an air flow that is passed through the exhaust treatment system. This airflow is not heated and cools the components of the exhaust treatment system, including the catalyst. When the catalyst is cooled to a temperature below the light-off temperature, the exhaust gas from the internal combustion engine may not be properly treated once fueled and running.

SUMMARY

A method for operating a hybrid vehicle is provided. The method includes determining whether an engine is rotating or not rotating, determining whether the engine is being fueled to produce a drive torque, when the engine is rotating, or not being fueled when the engine is rotating, and Directing an air flow generated by the internal combustion engine through a bypass path bypassing a primary catalyst to prevent the air flow from cooling the primary catalyst when the internal combustion engine is rotating and not being supplied with fuel.

A method for operating a hybrid vehicle is also provided. The method includes determining whether the engine is rotating or not rotating, determining whether the engine is being fueled to produce a drive torque when the engine is rotating, or not being fueled when the engine is rotating. When the engine rotates and is not fueled, a bypass valve of an exhaust treatment system is opened to direct an airflow generated by the engine through a bypass path bypassing a primary catalyst to prevent the airflow from cooling the primary catalyst , When the engine rotates and is supplied with fuel, the bypass valve is closed to direct a flow of exhaust gas generated by the internal combustion engine through the primary catalyst to treat the flow of exhaust gas. The method further comprises detecting a temperature of the primary catalyst when the engine is rotating and fueled, determining whether the sensed temperature of the primary catalyst is greater than a predefined temperature, and at least partially opening the bypass valve when the temperature of the primary catalyst greater than a predefined limit is to redirect at least a portion of the flow of exhaust gas generated by the engine through the bypass path to prevent the primary catalyst from overheating when the engine is rotating and fueled. The method further comprises treating the flow of exhaust gas diverted through the bypass path when the temperature of the primary catalyst is greater than the predefined limit with a second downstream catalyst.

There is also a vehicle provided. The vehicle includes a transmission that is configured to receive a drive torque and to transmit the drive torque to a drive wheel. An internal combustion engine is coupled to the transmission and configured to selectively provide the drive torque to the transmission. An exhaust treatment system is coupled to the internal combustion engine and configured to handle a flow of exhaust gas generated by the internal combustion engine when the internal combustion engine is supplied with fuel. An electric motor is coupled to the transmission and configured to selectively provide the drive torque to the transmission. When the electric motor supplies the drive torque to the transmission, the electric motor rotates the internal combustion engine in a non-fuel supplied state, whereby a flow of unheated air is generated by the exhaust treatment system. The exhaust treatment system includes a primary catalyst, a bypass path defining a fluid flow path bypassing the primary catalyst, and a bypass valve configured to control fluid flow between the primary catalyst and the bypass path. The bypass valve is disposed in an open position to direct air flow through the bypass path when the electric motor supplies the drive torque to the transmission and rotates the internal combustion engine. The bypass valve is disposed in a closed position to direct the flow of exhaust gas from the engine through the primary catalyst when the engine is fueled and provides the drive torque to the transmission.

Accordingly, when the electric motor provides the drive torque to the transmission and thereby rotates the engine, the flow of unheated air generated by the engine is directed through the bypass path, thereby bypassing the primary catalyst. Since the flow of unheated air is directed through the bypass path rather than over or through the primary catalyst, the unheated air from the rotating internal combustion engine does not cool the primary catalyst, thereby preventing primary catalyst from cooling to a temperature below a light-off temperature of the primary catalyst and thermal Efficiency of the primary catalyst can be maintained. The primary catalyst may therefore be ready to treat the exhaust gas from the internal combustion engine as soon as the internal combustion engine is supplied with fuel and is running.

The above features and advantages as well as other features and advantages of the present invention will be readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

1 FIG. 12 is a schematic plan view of an exhaust treatment system for an internal combustion engine of a hybrid vehicle. FIG.

2 is a schematic sectional view of a catalytic converter unit of the exhaust treatment system.

3 FIG. 10 is a flowchart showing a method of operating the hybrid vehicle to maintain the thermal efficiency of a primary catalyst of an exhaust treatment system.

DETAILED DESCRIPTION

Referring to the figures, wherein like numerals denote like parts throughout the several views, FIG 1 a hybrid vehicle in general with 20 shown. Referring to 1 indicates the hybrid vehicle 20 a gearbox 22 on. The gear 22 is configured to receive drive torque and transmit drive torque to a drive wheel (not shown). The gear 22 can be an automatic transmission 22 but is not limited thereto. The gear 22 takes the drive torque from the engine 24 and / or an electric motor 26 on. Both the internal combustion engine 24 as well as the electric motor 26 are with the gearbox 22 coupled and for selective delivery of the drive torque to the transmission 22 configured. The internal combustion engine 24 may include, but is not limited to, a gasoline engine or a diesel engine, and may be of any suitable size and / or configuration that is suitable for the initial and power requirements of the hybrid vehicle 20 to fulfill. The electric motor 26 may be any suitable size, type and / or configuration of the electric motor 26 suitable, the output and power requirements of the hybrid vehicle 20 to fulfill.

The hybrid vehicle 20 can either the internal combustion engine 24 or the electric motor 26 put into operation to generate the drive torque. The electric motor 26 delivers the entire drive torque when in operation. Thus turns when the electric motor 26 is in operation to only the drive torque to the gearbox 22 to deliver, the electric motor 26 also the internal combustion engine 24 , However, since the internal combustion engine 24 is not in operation to deliver the drive torque, the internal combustion engine 24 not fueled. Accordingly, when the electric motor rotates 26 is in operation to provide the drive torque, the electric motor 26 the internal combustion engine 24 in a non-fuel condition. When the internal combustion engine 24 in the non-fuel supplied state, the internal combustion engine generates 24 a flow of unheated air passing through an exhaust treatment system 28 flows.

The exhaust treatment system 28 is with the internal combustion engine 24 coupled. The treatment system 28 treats a flow of exhaust gas as indicated by arrow 30 is indicated by the internal combustion engine 24 when the internal combustion engine 24 is supplied with fuel, ie when the internal combustion engine 24 running. The exhaust treatment system 28 treats the flow of exhaust gas from the internal combustion engine 24 in order to reduce the toxicity of the exhaust gas, ie to reduce the toxic emissions of the exhaust gas, including, but not limited to, nitrogen oxides (NO), carbon monoxide (CO) and / or hydrocarbons (HC).

The exhaust treatment system 28 has a catalytic converter unit 32 on. The catalytic converter unit 32 is downstream of the internal combustion engine 24 arranged. The catalytic converter unit 32 has a primary catalyst 34 on. The primary catalyst 34 may include, but is not limited to, a three-way catalyst. The primary catalyst 34 may include platinum group metals (PGM) and convert a percentage of the nitrogen oxides in the exhaust into nitrogen and carbon dioxide or water, as well as oxidizing a percentage of the carbon monoxide to carbon dioxide and oxidizing a percentage of the unburned hydrocarbons to carbon dioxide and water. The catalytic converter unit 32 also defines a bypass path 36 , The bypass path 36 defines a fluid flow path that is the primary catalyst 34 bypasses. Also referring to 2 indicates the primary catalyst 34 a tubular shape. The tube shape is annular around the bypass path 36 arranged and defines this, where the bypass path 36 along a central opening of the tubular primary catalyst 34 extends.

A bypass valve 38 is also in the catalytic converter unit 32 arranged. The bypass valve 38 is to control a fluid flow between the primary catalyst 34 and the bypass path 36 configured. The bypass valve 38 is upstream of the primary catalyst 34 arranged and for opening and closing the fluid flow through the central region of the tubular primary catalyst 34 that the bypass path 36 defined, configured. The bypass valve 38 is movable between an open position and a closed position. When the bypass valve 38 is arranged in the open position, directs the bypass valve 38 a fluid flow, e.g. As air and / or exhaust gas flow, through the bypass path 36 , Thus, if the electric motor 26 exclusively the entire drive torque to the transmission 22 supplies and thereby the internal combustion engine 24 turns, the bypass valve 38 be arranged in the open position to the flow of air through the bypass path 36 to the primary catalyst 34 to steer around and thereby the primary catalyst 34 to get around. When the bypass valve 38 is arranged in the closed position, directs the bypass valve 38 the fluid flow, z. B. air and / or exhaust gas flow through the primary catalyst 34 , Thus, if the internal combustion engine 24 is supplied with fuel to deliver the drive torque, the bypass valve 38 be arranged in the closed position to the flow of exhaust gas from the internal combustion engine 24 through the primary catalyst 34 to steer.

As shown, the catalytic converter unit 32 further a secondary catalyst 40 exhibit. The secondary catalyst 40 is downstream of the primary catalyst 34 arranged. The secondary catalyst 40 is configured to control the flow of exhaust gas passing through either the primary catalyst 34 or through the bypass path 36 flows, to treat. Accordingly, when exhaust gas from the internal combustion engine 24 through the bypass path 36 is directed, then treated the secondary catalyst 40 the exhaust. The secondary catalyst 40 may include, but is not limited to, a three way catalyst. The secondary catalyst 40 may include platinum group metals (PGM) and convert a percentage of the nitrogen oxides in the exhaust into nitrogen and carbon dioxide or water, as well as oxidizing a percentage of the carbon monoxide to carbon dioxide and oxidizing a percentage of the unburned hydrocarbons to carbon dioxide and water.

Referring to 3 is a method of operating the hybrid vehicle 20 as described above. The procedure is in 3 generally with 50 shown. The procedure 50 includes determining if an internal combustion engine 24 turns or does not turn, as generally by block 52 is specified. When the internal combustion engine 24 is determined as not rotating, as in 54 is specified and not fueled, the process can 50 a closing of the bypass valve 38 as generally by block 56 is specified. When the internal combustion engine 24 is determined as turning, as in 58 is specified.

The procedure 50 may further comprise that the electric motor 26 is put into operation to selectively drive torque to the electric motor 26 as generally by block 60 is specified. As described above, the operation of the electric motor rotates 26 also the Internal combustion engine 24 , whereby the air flow from the internal combustion engine 24 is generated by the exhaust treatment system 28 flows. Alternatively, the process may 50 Furthermore, a Beliefern the internal combustion engine 24 having fuel to generate the drive torque, as generally by block 62 is specified. As described above, supplying the internal combustion engine generates 24 with fuel, ie running the internal combustion engine 24 , a flow of heated exhaust gas that needs to be treated.

The method further comprises determining if the internal combustion engine 24 fueled or not, as generally by block 64 is specified. When the internal combustion engine 24 turns like at 58 is specified, the internal combustion engine 24 be supplied with fuel to produce the drive torque, as at 66 is specified. Alternatively, as described above, the internal combustion engine 24 as a result turn that the electric motor 26 is in operation to produce the drive torque, and thus is not supplied with fuel, as at 68 is specified.

When it is determined that the internal combustion engine 24 turns like at 58 fuel is not supplied, as in 68 is specified, then the method 50 Further, directing the flow of air through the internal combustion engine 24 is generated by the bypass path 36 as generally by block 70 is specified to the primary catalyst 34 to get around. Directing the flow of unheated air around the primary catalyst 34 , whereby the primary catalyst 34 bypassing, prevents the airflow to the primary catalyst 34 cools. Accordingly, the primary catalyst 34 stay at a preheated temperature, thereby being ready with exhaust from the engine 24 to react when the internal combustion engine 24 supplied with fuel. The steering of the air flow, by the internal combustion engine 24 is generated by the bypass path 36 can also be considered opening the bypass valve 38 be defined to the air flow passing through the engine 24 is generated by the bypass path 36 to steer. However, it should be noted that the air flow from the internal combustion engine 24 through the bypass path 36 can be performed in any other way that is not shown or described here.

When it is determined that the internal combustion engine 24 turns like at 58 is specified and supplied with fuel, as with 66 is specified, the method can 50 then further directing the flow of exhaust gas passing through the engine 24 is generated by the primary catalyst 34 as generally by block 72 is specified to treat the flow of exhaust gas. The steering of the flow of exhaust gas by the internal combustion engine 24 is generated by the primary catalyst 34 can also be considered as closing the bypass valve 38 be defined to the flow of exhaust gas passing through the engine 24 is generated by the primary catalyst 34 to steer. However, it should be noted that the flow of exhaust gas from the internal combustion engine 24 through the primary catalyst 34 in any other way that is not shown or described here.

The procedure 50 may further include detecting a temperature of the primary catalyst 34 as generally by block 74 is specified. The temperature of the primary catalyst 34 can be suitably detected, including, but not limited to, sensing the temperature of the primary catalyst 34 with one in the catalytic converter unit 32 arranged temperature sensor. The temperature of the primary catalyst 34 can be detected at any time, however, it is particularly important the temperature of the primary catalyst 34 detect when the engine is turning and fueled. The useful life expectancy of the primary catalyst 34 can be reduced if the temperature of the primary catalyst 34 is overheated. Accordingly, the method comprises 50 determining if the sensed temperature of the primary catalyst 34 greater than a predefined temperature, as generally by block 76 is specified. The predefined temperature is an upper operating temperature of the primary catalyst 34 , The predefined temperature is a temperature that is set to a level that ensures that the primary catalyst 34 not overheated. Accordingly, as long as the primary catalyst 34 is at or below the predefined temperature, the primary catalyst 34 do not overheat.

To ensure that the primary catalyst 34 not overheated when the temperature of the primary catalyst 34 is greater than the predefined limit, as with 78 is specified, the method can 50 Furthermore, at least partial opening of the bypass valve 38 as generally by block 80 is specified. Opening the bypass valve 38 directs at least a portion of the flow of exhaust gas passing through the engine 24 is generated by the bypass path 36 , causing overheating of the primary catalyst 34 is prevented. The flow of exhaust gas passing through the bypass path 36 is then diverted to the secondary catalyst 40 treated. When the temperature of the primary catalyst 34 less than the predefined limit, as with 82 is specified, the method can 50 further holding the bypass valve 38 in the closed position, as generally by block 84 is specified.

While the best modes for carrying out the invention have been described in detail, those skilled in the art will recognize various alternative constructions and embodiments for carrying out the invention within the scope of the appended claims.

Claims (10)

A method of operating a hybrid vehicle, the method comprising: Determining whether an internal combustion engine is rotating or not rotating; Determining whether the engine is being fueled to produce a drive torque when the engine is rotating or not being fueled when the engine is rotating; and Directing an air flow generated by the internal combustion engine through a bypass path bypassing a primary catalyst to prevent the air flow from cooling the primary catalyst when the internal combustion engine is rotating and not being supplied with fuel. The method of claim 1, further comprising directing a flow of exhaust gas generated by the internal combustion engine through the primary catalyst to treat the flow of exhaust gas as the internal combustion engine rotates and is supplied with fuel. The method of claim 2, wherein directing the flow of air generated by the internal combustion engine through the bypass path is further defined as opening a bypass valve to direct the flow of air generated by the internal combustion engine through the bypass path. The method of claim 3, wherein directing the flow of exhaust gas generated by the internal combustion engine through the primary catalyst is further defined as closing the bypass valve to direct the flow of exhaust gas generated by the internal combustion engine through the primary catalyst. The method of claim 1, further comprising detecting a temperature of the primary catalyst. The method of claim 5, wherein detecting the temperature of the primary catalyst is further defined as detecting the temperature of the primary catalyst when the engine is rotating and fueled. The method of claim 6, further comprising determining if the sensed temperature of the primary catalyst is greater than a predefined temperature. The method of claim 7, further comprising at least partially opening the bypass valve when the temperature of the primary catalyst is greater than a predefined limit to at least divert a portion of the flow of exhaust gas generated by the internal combustion engine through the bypass path to overheat prevent the primary catalyst. The method of claim 8, further comprising treating the flow of exhaust gas diverted through the bypass path when the temperature of the primary catalyst is greater than the predefined limit with a second downstream catalyst. The method of claim 1, further comprising closing the by-pass valve when the engine is not rotating and is not being fueled.

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