WO2008118073A1 - Exhaust gas brake control - Google Patents
Exhaust gas brake control Download PDFInfo
- Publication number
- WO2008118073A1 WO2008118073A1 PCT/SE2008/050305 SE2008050305W WO2008118073A1 WO 2008118073 A1 WO2008118073 A1 WO 2008118073A1 SE 2008050305 W SE2008050305 W SE 2008050305W WO 2008118073 A1 WO2008118073 A1 WO 2008118073A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- control signal
- engine
- adjustable valve
- exhaust gas
- exhaust
- Prior art date
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
- F02D41/221—Safety or indicating devices for abnormal conditions relating to the failure of actuators or electrically driven elements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D21/00—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas
- F02D21/06—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air
- F02D21/08—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air the other gas being the exhaust gas of engine
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1448—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an exhaust gas pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
- F02D9/04—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning exhaust conduits
- F02D9/06—Exhaust brakes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/02—EGR systems specially adapted for supercharged engines
- F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
- F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/20—Output circuits, e.g. for controlling currents in command coils
- F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
- F02D2041/2024—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit the control switching a load after time-on and time-off pulses
- F02D2041/2027—Control of the current by pulse width modulation or duty cycle control
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0002—Controlling intake air
- F02D41/0007—Controlling intake air for control of turbo-charged or super-charged engines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D41/0047—Controlling exhaust gas recirculation [EGR]
- F02D41/005—Controlling exhaust gas recirculation [EGR] according to engine operating conditions
- F02D41/0055—Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/04—Introducing corrections for particular operating conditions
- F02D41/12—Introducing corrections for particular operating conditions for deceleration
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Definitions
- the present invention relates generally to brake solutions for motor vehicles that are based on exhaust gas restriction. More particularly the invention relates to an exhaust brake system according to the preamble of claim 1 and a motor vehicle according to claim 8. The invention also relates to a method of controlling an exhaust gas brake according to the preamble of claim 9 and a computer program product according to claim 15.
- An exhaust brake system for a combustion-engine vehicle typically includes a valve, which is arranged in the engine's exhaust passage.
- the valve When the exhaust brake is activated, the valve is controlled to a position wherein it obstructs the exhaust gasses flowing from the engine. Thereby, the pistons in the engine ex- perience an increased resistance during the engine's exhaust stroke, and consequently a brake effect occurs.
- solutions are know for handling various exhaust-gas-brake related problems.
- JP 2001 -263134 discloses an auxiliary brake device, which is designed to accurately adjust the exhaust gas pressure of an engine during operation of the exhaust brake.
- an excessive exhaust gas pressure is avoided by adjusting a valve in an exhaust gas recirculation (EGR) passage that connects an upstream side of the exhaust gas brake valve with an air intake to the engine.
- EGR exhaust gas recirculation
- JP 2004-324417 describes an EGR system capable of preventing damages of an EGR cooler due to a pressure wave generated during operation of an exhaust gas brake.
- the design includes a shut-off valve for the EGR valve, which is activated upon activation of the exhaust gas brake.
- JP 2001 -280173 reveals an exhaust braking device for an internal combustion engine.
- a bypass passage is opened over the exhaust braking device in case of an electric short-circuit in respect of the exhaust braking device. Thereby, unintentional exhaust gas braking can be avoided.
- This system is advantageous because it provides an automatic testing of the exhaust brake, which will be executed at repeated occasions during normal operation of the vehicle.
- the first and second threshold levels represent a motoring state in which the engine does not propel the vehicle. Hence, no disrupting pressures will be built up in the exhaust gas conduit during the test procedure.
- the control unit is adapted to receive a status signal indicative of a functionality condition of an actuating means adapted to influence an adjustment of the first adjustable valve.
- the actuating means may include a piston member and a valve means.
- the piston member is here operative in response to a pressurized fluid (e.g. compressed air or hydraulic oil), and the valve means is operative in response to the first control signal.
- the valve means is adapted to forward the pressurized fluid to the piston member.
- the control unit is further adapted to test whether or not the status signal fulfills an alarm criterion, and if so, generate the second control signal such that the second adjustable valve is adjusted to a predetermined position, preferably fully opened.
- the first control signal is an electric-type of signal, and the status signal is based on at least one electric parameter associated with an operation of the actuating means.
- the first control signal may have a pulse-width-modulation (PWM) format, and the first adjustable valve may be adapted to open a passage for the exhaust gasses from the engine based on a pulse width of the first control signal. Consequently, a short circuit of the first adjustable valve to the supply voltage might be interpreted as an order to fully close exhaust gas brake valve. This highly undesired effect, however, is avoided by the above- described testing of the status signal.
- PWM pulse-width-modulation
- the object is achieved by the motor vehicle described initially, wherein the vehicle includes the above-described exhaust brake system that is configured to apply an adjustable brake-torque with respect to at least one drive axis of the vehicle's engine.
- the object is achieved by the method described initially, wherein it is checked if the set value designates a brake-torque below a first threshold level and if the engine is controlled to a drive-torque below a second threshold level. If both these conditions are fulfilled, the method further involves: generating the second control signal such that the second adjustable valve is adjusted to a closed position and generating the third control signal such that the turbo unit opens up maximally with respect to the exhaust gasses. Thereafter, it is tested if the exhaust gas pressure level exceeds a third threshold level, and if so, the method involves producing an alarm triggering signal in respect of the first adjustable valve.
- the object is achieved by a computer program product loadable into a memory of a computer.
- the program product includes software adap- ted to control the above proposed method when the program product is run on a computer.
- Figure 1 shows a block diagram over an exhaust brake system according to one embodiment of the invention
- Figures 2a-b show diagrams illustrating a format of a control signal and its relationship to an opening of the exhaust brake valve according to one embodiment of the invention
- Figure 3 shows a motor vehicle including the proposed exhaust brake system
- Figure 4 shows a flow diagram illustrating the general method according to the invention.
- Figure 1 shows a block diagram over an exhaust brake system for a motor vehicle according to one embodiment of the invention.
- the system includes a first adjustable valve 135, a second adjustable valve 107, a sensor means 155, a turbo unit 160 and a control unit 120, which is adapted to receive an exhaust gas pressure signal P m from the sensor means 155 and a set value T req designating a desired brake-torque to be applied by the exhaust gas brake.
- the control unit 120 is adapted to generate a first, second and third control signal C1 , C2 and C3 respectively, and an alarm triggering signal A in respect of the first adjustable valve 135.
- the first adjustable valve 135 is arranged in an exhaust gas conduit 150 from an internal combustion engine 1 10 of the vehicle and is adapted to obstruct the engine's 1 10 exhaust gasses E out in response to the first control signal C1 , and as a result, cause a brake-torque during the engine's 1 10 exhaust stroke.
- the second adjustable valve 107 is arranged in a recirculation passage 1 15 connecting the exhaust gas conduit 150 with an air intake 105 to the engine 1 10. The second adjustable valve 107 is operable in response to the second control signal C2.
- the sensor means 155 is arranged to register the exhaust gas pressure level P m in the exhaust gas conduit 150 between the engine 1 10 and the first adjustable valve means 135, and forward the exhaust gas pressure signal P m to the control unit 120.
- the turbo unit 160 is arranged in the exhaust gas conduit 150, and is controllable in response to the third control signal C3.
- the control unit 120 is adapted to repeatedly check if the set value T req designates a brake-torque below a first threshold level. Additionally, the control unit 120 is adapted to repeatedly check if the engine 1 10 is controlled to a drive-torque below a second threshold level.
- the first and second threshold levels are set to such low values that they represent a motoring state in which the engine 1 10 does not propel the vehicle (and at the same time brakes the vehicle insignificantly). If the control unit 120 finds that both the above conditions are fulfilled simultaneously (i.e.
- the control unit 120 is adapted to generate the second control signal C2 such that the second adjustable valve 107 is adjusted to a closed position. Consequently, no exhaust gasses E r will be recirculated from the engine's 1 10 exhaust gas output to its air intake.
- Figure 1 shows the second adjustable valve 107 being arranged relatively proximate to the air intake. However, the valve 107 may equally well be located at any other position in the recirculation passage 1 15, e.g. at the intersection between the recirculation passage 1 15 and the exhaust gas conduit 150.
- the control unit 120 Upon simultaneous fulfillment of the above two conditions (i.e. the set value T req designating a brake-torque below a first threshold level and the drive-torque being below the second threshold level), the control unit 120 is also adapted to generate the third control signal C3 such that the turbo unit 160 opens up maximally with respect to the exhaust gasses E out .
- the exhaust gasses E out will have minimal influence on an amount of air A in fed to the engine's 1 10 air intake. More important, however, the turbo unit 160 will restrict the exhaust gasses E out minimally. Therefore, the influence of the first adjustable valve 135 of the exhaust gas brake can be tested in a straightforward manner.
- the control unit 120 is adapted to test if the exhaust gas pressure level P m exceeds a third threshold level. If this condition is found to be fulfilled, the control unit 120 is adapted to produce the alarm triggering signal A (i.e. to indicate a malfunction of the first adjustable valve 135).
- the alarm triggering signal A reflects a jammed condition for the exhaust brake valve.
- the set value T req designates a desired brake-torque below the first threshold level, say a zero value, while the exhaust gas pressure level P m shows an abnormally high value exceeding the third threshold level.
- the turbo unit 160 may be arranged at arbitrary position relative to the first adjustable valve means 135.
- the turbo unit 160 may be located between the engine 1 10 and the first adjustable valve means 135.
- the first adjustable valve means 135 is a distinct component separated from the turbo unit 160. Consequently, the valve means 135 cannot for example be represented by the nozzle-area adjusting guide vanes of a variable geometry turbo (VGT).
- VVT variable geometry turbo
- the control unit 120 is further adapted to receive a status signal m v indicative of a functionality condition of an actuating means adapted to influence an adjustment of the first adjustable valve 135.
- the actuating means preferably includes a piston member 130 and a valve means 145.
- the valve means 145 is operative in response to the first control signal C1 .
- This signal C1 may thus cause the valve means 145 to open up and forward a pressurized fluid Fp (e.g. in the form of compressed air or hydraulic oil) to the piston member 130.
- the pressurized fluid F P is preferably supplied by a pump means 140 in the vehicle.
- the piston member 130 is operative in response to a pressurized fluid F P This means that the piston member 130 will cause the first adjustable valve means 135 to adjust its position depending on the status of the valve means 145.
- control unit 120 is adapted to test whether or not the status signal m v originated by the valve means 145 fulfills an alarm criterion. If so, the control unit 120 is further adapted to generate the second control signal C2 such that the second adjustable valve 107 is adjusted to a predetermined posi- tion, preferably fully open.
- the valve means 145 is configured to be driven by a supply voltage +U, and the first control signal C1 is an electric-type of signal.
- the status signal m v is based on an electric parameter associated with an operation of the valve means 145.
- the status signal m v may here reflect whether or not the valve means 145 has been short-circuited to the supply voltage +U.
- Figure 2a shows a diagram illustrating a format of the first control signal C1 according to one embodiment of the invention.
- the signal C1 has a PWM format.
- the opening of the first adjustable valve means 135 is inversely proportional to a pulse width of the signal C1 , such that a relatively narrow pulse, say 0,25T, results in a comparatively large valve opening, and vice versa, a relatively wide pulse, say 0,95T, results in a comparatively small valve opening.
- Figure 2b shows a diagram specifically illustrating this relation- ship, where the vertical axis reflects the opening angle ⁇ of the first adjustable valve 135 and the horizontal axis designates the pulse width PW C i for the PWM signal C1 ranging from zero to a maximum value T (given by the period time of the PWM signal C1 ).
- a largest possible opening angle ⁇ corresponds to a fully opened FO valve 135, and a zero opening angle ⁇ corresponds to a fully closed FC valve 135.
- the first control signal C1 alternates between a ground-level voltage and the supply voltage +U with a pulse cycle T.
- short- circuiting the valve means 145 to the supply voltage +U has the same effect as deliberately controlling the valve 135 to a fully closed position.
- an unintentional closure of the valve 135 e.g. due to a short circuit of the valve means 145) may lead to highly undesired results, such as damages to the engine 1 10, the exhaust conduit 150 and/or the turbo unit 160.
- FIG. 3 shows a motor vehicle 200 including the proposed exhaust brake system, which is configured to apply an adjustable brake-torque with respect to at least one drive axis of the engine 1 10.
- the system has a control unit 120 adapted to test the operative status of the first adjustable valve 135 as has been described above.
- a first step 410 investigates whether or not a set value is received which designates an exhaust gas brake-torque below a first threshold level.
- Step 410 also investigates whether or not the engine is controlled to a drive-torque below a second threshold level. If it is found that both these conditions are fulfilled simul- taneously, a step 420 follows. Otherwise, the procedure loops back and stays in step 410 (i.e. If it is found that the set value designates an exhaust gas brake-torque equal to or above the first threshold level and/or the drive-torque is equal to, or above the second threshold level).
- Step 420 generates a signal such that the EGR valve (e.g. represented by the second adjustable valve 107 in Figure 1 ) is adjusted to a closed position.
- a step 430 generates a control signal such that the turbo unit opens up maximally with respect to the exhaust gasses.
- a step 440 tests if the ex- haust gas pressure level exceeds a third threshold level, and if so, a step 450 follows. Otherwise, the procedure loops back to step 410.
- Step 450 produces an alarm triggering signal in respect of the first adjustable valve. Thereafter, the procedure may either end, or loop back to step 410 for continued supervision of the exhaust gas brake system.
- All of the process steps, as well as any sub-sequence of steps, described with reference to the figure 4 above may be controlled by means of a programmed computer apparatus.
- the embodiments of the invention described above with reference to the drawings comprise computer apparatus and processes performed in computer apparatus, the invention thus also extends to computer programs, particularly computer programs on or in a carrier, adapted for putting the invention into practice.
- the program may be in the form of source code; object code, a code intermediate source and object code such as in partially compiled form, or in any other form suitable for use in the implementation of the process according to the invention.
- the carrier may be any entity or device capable of carrying the program.
- the carrier may comprise a storage medium, such as a Flash memory, a ROM (Read Only Memory), for example a CD (Compact Disc) or a semiconductor ROM, an EPROM (Erasable Programmable Read-Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a magnetic recording medium, for example a floppy disc or hard disc.
- the carrier may be a transmissible carrier such as an electrical or optical signal which may be conveyed via electrical or optical cable or by radio or by other means.
- the carrier may be constituted by such cable or device or means.
- the carrier may be an integrated circuit in which the program is embedded, the integrated circuit being adapted for performing, or for use in the performance of, the relevant processes.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
Abstract
An exhaust brake system for a motor vehicle, comprising an adjustable valve (107) in a recirculation passage (115) connecting an exhaust gas conduit (150) with an air intake (105) to the engine (110), and a control unit (120) that produces a first control signal (Cl) in response to a set value (Treq) designating a desired brake -torque, the control unit being adapted to: check if the set value (Treq) designates a brake-torque below a first threshold level and the engine (110) is controlled to a drive-torque below a second threshold level, and if both these conditions are fulfilled, generate a second control signal (C2) such that the adjustable valve (107) is adjusted to a closed position, generate a third control signal (C3) such that the turbo unit (160) opens up maximally with respect to the exhaust gasses (Eout), test if the exhaust gas pressure level (Pm) exceeds a third threshold level, and if so, produces an alarm triggering signal (A) in respect of a first adjustable valve (135) that obstructs the exhaust gas from the engine.
Description
Exhaust Gas Brake Control
THE BACKGROUND OF THE INVENTION AND PRIOR ART
The present invention relates generally to brake solutions for motor vehicles that are based on exhaust gas restriction. More particularly the invention relates to an exhaust brake system according to the preamble of claim 1 and a motor vehicle according to claim 8. The invention also relates to a method of controlling an exhaust gas brake according to the preamble of claim 9 and a computer program product according to claim 15.
An exhaust brake system for a combustion-engine vehicle typically includes a valve, which is arranged in the engine's exhaust passage. When the exhaust brake is activated, the valve is controlled to a position wherein it obstructs the exhaust gasses flowing from the engine. Thereby, the pistons in the engine ex- perience an increased resistance during the engine's exhaust stroke, and consequently a brake effect occurs. Additionally, solutions are know for handling various exhaust-gas-brake related problems.
JP 2001 -263134 discloses an auxiliary brake device, which is designed to accurately adjust the exhaust gas pressure of an engine during operation of the exhaust brake. Here, an excessive exhaust gas pressure is avoided by adjusting a valve in an exhaust gas recirculation (EGR) passage that connects an upstream side of the exhaust gas brake valve with an air intake to the engine.
JP 2004-324417 describes an EGR system capable of preventing damages of an EGR cooler due to a pressure wave generated during operation of an exhaust gas brake. The design includes a shut-off valve for the EGR valve, which is activated upon activation of the exhaust gas brake.
JP 2001 -280173 reveals an exhaust braking device for an internal combustion engine. Here, a bypass passage is opened over
the exhaust braking device in case of an electric short-circuit in respect of the exhaust braking device. Thereby, unintentional exhaust gas braking can be avoided.
However, there is no solution wherein information regarding the actual positioning of the exhaust brake valve is fed back to the control unit responsible for exhaust-gas-brake function. Thus, even if a control signal has been generated which is intended to control the exhaust brake valve to an open position, the valve may in fact be closed, or at least be positioned differently than what is reflected by the control signal. This, in turn, may result in material damages (e.g. to the engine and/or to its associated valves and turbo units) as well as safety risks due to unexpected braking of the vehicle.
SUMMARY OF THE INVENTION The object of the present invention is therefore to provide a solution, which alleviates the problems above, and thus offers a reliable supervision of the exhaust brake valve functionality.
According to one aspect of the invention, the object is achieved by the initially described exhaust brake system, wherein the control unit is adapted to check if the set value designates a brake-torque below a first threshold level and the engine is controlled to a drive-torque below a second threshold level. If both these conditions are fulfilled, the control unit is adapted to: generate the second control signal such that the second adjustable valve is adjusted to a closed position, generate the third control signal such that the turbo unit opens up maximally with respect to the exhaust gasses, and then test if the exhaust gas pressure level exceeds a third threshold level. If this is found to be the case, the control unit is adapted to produce an alarm triggering signal in respect of the first adjustable valve.
This system is advantageous because it provides an automatic testing of the exhaust brake, which will be executed at repeated occasions during normal operation of the vehicle.
According to one embodiment of this aspect of the invention, the
first and second threshold levels represent a motoring state in which the engine does not propel the vehicle. Hence, no disrupting pressures will be built up in the exhaust gas conduit during the test procedure.
According to another embodiment of this aspect of the invention, the control unit is adapted to receive a status signal indicative of a functionality condition of an actuating means adapted to influence an adjustment of the first adjustable valve. For example, the actuating means may include a piston member and a valve means. The piston member is here operative in response to a pressurized fluid (e.g. compressed air or hydraulic oil), and the valve means is operative in response to the first control signal. The valve means is adapted to forward the pressurized fluid to the piston member. The control unit is further adapted to test whether or not the status signal fulfills an alarm criterion, and if so, generate the second control signal such that the second adjustable valve is adjusted to a predetermined position, preferably fully opened. Thereby, in addition to detecting a malfunctioning exhaust brake, the proposed system can also reduce the effects of certain malfunctions.
According to yet another embodiment of this aspect of the invention, the first control signal is an electric-type of signal, and the status signal is based on at least one electric parameter associated with an operation of the actuating means. For example, the first control signal may have a pulse-width-modulation (PWM) format, and the first adjustable valve may be adapted to open a passage for the exhaust gasses from the engine based on a pulse width of the first control signal. Consequently, a short circuit of the first adjustable valve to the supply voltage might be interpreted as an order to fully close exhaust gas brake valve. This highly undesired effect, however, is avoided by the above- described testing of the status signal.
According to another aspect of the invention, the object is achieved by the motor vehicle described initially, wherein the vehicle includes the above-described exhaust brake system that is configured to apply an adjustable brake-torque with respect to at
least one drive axis of the vehicle's engine.
According to another aspect of the invention, the object is achieved by the method described initially, wherein it is checked if the set value designates a brake-torque below a first threshold level and if the engine is controlled to a drive-torque below a second threshold level. If both these conditions are fulfilled, the method further involves: generating the second control signal such that the second adjustable valve is adjusted to a closed position and generating the third control signal such that the turbo unit opens up maximally with respect to the exhaust gasses. Thereafter, it is tested if the exhaust gas pressure level exceeds a third threshold level, and if so, the method involves producing an alarm triggering signal in respect of the first adjustable valve. The advantages of this method, as well as the preferred embodiments thereof, are apparent from the discussion hereinabove with reference to the proposed vehicle arrangement.
According to a further aspect of the invention the object is achieved by a computer program product loadable into a memory of a computer. The program product includes software adap- ted to control the above proposed method when the program product is run on a computer.
BRIEF DESCRI PTION OF THE DRAWINGS
The present invention is now to be explained more closely by means of embodiments, which are disclosed as examples, and with reference to the attached drawings.
Figure 1 shows a block diagram over an exhaust brake system according to one embodiment of the invention, and
Figures 2a-b show diagrams illustrating a format of a control signal and its relationship to an opening of the exhaust brake valve according to one embodiment of the invention,
Figure 3 shows a motor vehicle including the proposed exhaust brake system, and
Figure 4 shows a flow diagram illustrating the general method according to the invention.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
We refer initially to Figure 1 , which shows a block diagram over an exhaust brake system for a motor vehicle according to one embodiment of the invention.
The system includes a first adjustable valve 135, a second adjustable valve 107, a sensor means 155, a turbo unit 160 and a control unit 120, which is adapted to receive an exhaust gas pressure signal Pm from the sensor means 155 and a set value Treq designating a desired brake-torque to be applied by the exhaust gas brake. Moreover, the control unit 120 is adapted to generate a first, second and third control signal C1 , C2 and C3 respectively, and an alarm triggering signal A in respect of the first adjustable valve 135.
The first adjustable valve 135 is arranged in an exhaust gas conduit 150 from an internal combustion engine 1 10 of the vehicle and is adapted to obstruct the engine's 1 10 exhaust gasses Eout in response to the first control signal C1 , and as a result, cause a brake-torque during the engine's 1 10 exhaust stroke. The second adjustable valve 107 is arranged in a recirculation passage 1 15 connecting the exhaust gas conduit 150 with an air intake 105 to the engine 1 10. The second adjustable valve 107 is operable in response to the second control signal C2.
The sensor means 155 is arranged to register the exhaust gas pressure level Pm in the exhaust gas conduit 150 between the engine 1 10 and the first adjustable valve means 135, and forward the exhaust gas pressure signal Pm to the control unit 120. The turbo unit 160 is arranged in the exhaust gas conduit 150, and is controllable in response to the third control signal C3.
The control unit 120 is adapted to repeatedly check if the set value Treq designates a brake-torque below a first threshold
level. Additionally, the control unit 120 is adapted to repeatedly check if the engine 1 10 is controlled to a drive-torque below a second threshold level. Preferably, the first and second threshold levels are set to such low values that they represent a motoring state in which the engine 1 10 does not propel the vehicle (and at the same time brakes the vehicle insignificantly). If the control unit 120 finds that both the above conditions are fulfilled simultaneously (i.e. that the set value Treq designates a brake-torque below a first threshold level and the drive- torque to which the engine is controlled is below the second threshold level), the control unit 120 is adapted to generate the second control signal C2 such that the second adjustable valve 107 is adjusted to a closed position. Consequently, no exhaust gasses Er will be recirculated from the engine's 1 10 exhaust gas output to its air intake. Figure 1 shows the second adjustable valve 107 being arranged relatively proximate to the air intake. However, the valve 107 may equally well be located at any other position in the recirculation passage 1 15, e.g. at the intersection between the recirculation passage 1 15 and the exhaust gas conduit 150.
Upon simultaneous fulfillment of the above two conditions (i.e. the set value Treq designating a brake-torque below a first threshold level and the drive-torque being below the second threshold level), the control unit 120 is also adapted to generate the third control signal C3 such that the turbo unit 160 opens up maximally with respect to the exhaust gasses Eout. Hence, the exhaust gasses Eout will have minimal influence on an amount of air Ain fed to the engine's 1 10 air intake. More important, however, the turbo unit 160 will restrict the exhaust gasses Eout minimally. Therefore, the influence of the first adjustable valve 135 of the exhaust gas brake can be tested in a straightforward manner. To this aim, the control unit 120 is adapted to test if the exhaust gas pressure level Pm exceeds a third threshold level. If this condition is found to be fulfilled, the control unit 120 is adapted to produce the alarm triggering signal A (i.e. to indicate a malfunction of the first adjustable valve 135). Preferably, the alarm triggering signal A reflects a jammed condition for the
exhaust brake valve. Namely, the set value Treq designates a desired brake-torque below the first threshold level, say a zero value, while the exhaust gas pressure level Pm shows an abnormally high value exceeding the third threshold level.
Referring to Figure 1 , it is worth mentioning that, according to the invention, the turbo unit 160 may be arranged at arbitrary position relative to the first adjustable valve means 135. For example, the turbo unit 160 may be located between the engine 1 10 and the first adjustable valve means 135. Additionally, it should be pointed out that the first adjustable valve means 135 is a distinct component separated from the turbo unit 160. Consequently, the valve means 135 cannot for example be represented by the nozzle-area adjusting guide vanes of a variable geometry turbo (VGT).
According to one embodiment of the invention, the control unit 120 is further adapted to receive a status signal mv indicative of a functionality condition of an actuating means adapted to influence an adjustment of the first adjustable valve 135. The actuating means, in turn, preferably includes a piston member 130 and a valve means 145. The valve means 145 is operative in response to the first control signal C1 . This signal C1 may thus cause the valve means 145 to open up and forward a pressurized fluid Fp (e.g. in the form of compressed air or hydraulic oil) to the piston member 130. The pressurized fluid FP. is preferably supplied by a pump means 140 in the vehicle. The piston member 130 is operative in response to a pressurized fluid FP This means that the piston member 130 will cause the first adjustable valve means 135 to adjust its position depending on the status of the valve means 145.
Specifically, the control unit 120 is adapted to test whether or not the status signal mv originated by the valve means 145 fulfills an alarm criterion. If so, the control unit 120 is further adapted to generate the second control signal C2 such that the second adjustable valve 107 is adjusted to a predetermined posi- tion, preferably fully open.
According to one embodiment of the invention, the valve means 145 is configured to be driven by a supply voltage +U, and the
first control signal C1 is an electric-type of signal. In this case, the status signal mv is based on an electric parameter associated with an operation of the valve means 145. For example, the status signal mv may here reflect whether or not the valve means 145 has been short-circuited to the supply voltage +U.
Figure 2a shows a diagram illustrating a format of the first control signal C1 according to one embodiment of the invention. The signal C1 has a PWM format. Furthermore, the opening of the first adjustable valve means 135 is inversely proportional to a pulse width of the signal C1 , such that a relatively narrow pulse, say 0,25T, results in a comparatively large valve opening, and vice versa, a relatively wide pulse, say 0,95T, results in a comparatively small valve opening.
Figure 2b shows a diagram specifically illustrating this relation- ship, where the vertical axis reflects the opening angle φ of the first adjustable valve 135 and the horizontal axis designates the pulse width PWCi for the PWM signal C1 ranging from zero to a maximum value T (given by the period time of the PWM signal C1 ). Hence, a largest possible opening angle φ corresponds to a fully opened FO valve 135, and a zero opening angle φ corresponds to a fully closed FC valve 135.
Returning now to Figure 2a, we see that the first control signal C1 alternates between a ground-level voltage and the supply voltage +U with a pulse cycle T. A widest possible pulse (i.e. having pulse width PWCi = T) is thus equivalent to that the first control signal C1 is constantly equal to +U. Consequently, short- circuiting the valve means 145 to the supply voltage +U has the same effect as deliberately controlling the valve 135 to a fully closed position. However, an unintentional closure of the valve 135 (e.g. due to a short circuit of the valve means 145) may lead to highly undesired results, such as damages to the engine 1 10, the exhaust conduit 150 and/or the turbo unit 160. Naturally, the vehicle will also be braked, which might cause handling problems (e.g. manifested in skidding or over steering), especially if the vehicle is connected to a lightly loaded, or unloaded trailer. Nevertheless, one embodiment of the present invention mitigates this problem by opening the EGR valve (107) as described above.
Figure 3 shows a motor vehicle 200 including the proposed exhaust brake system, which is configured to apply an adjustable brake-torque with respect to at least one drive axis of the engine 1 10. Thus, the system has a control unit 120 adapted to test the operative status of the first adjustable valve 135 as has been described above.
In order to sum up, the general method of testing an exhaust brake in a motor vehicle according to the invention will be described below with reference to the flow diagram in figure 4.
A first step 410 investigates whether or not a set value is received which designates an exhaust gas brake-torque below a first threshold level. Step 410 also investigates whether or not the engine is controlled to a drive-torque below a second threshold level. If it is found that both these conditions are fulfilled simul- taneously, a step 420 follows. Otherwise, the procedure loops back and stays in step 410 (i.e. If it is found that the set value designates an exhaust gas brake-torque equal to or above the first threshold level and/or the drive-torque is equal to, or above the second threshold level).
Step 420 generates a signal such that the EGR valve (e.g. represented by the second adjustable valve 107 in Figure 1 ) is adjusted to a closed position. Subsequently, a step 430 generates a control signal such that the turbo unit opens up maximally with respect to the exhaust gasses. Then, a step 440 tests if the ex- haust gas pressure level exceeds a third threshold level, and if so, a step 450 follows. Otherwise, the procedure loops back to step 410. Step 450 produces an alarm triggering signal in respect of the first adjustable valve. Thereafter, the procedure may either end, or loop back to step 410 for continued supervision of the exhaust gas brake system.
All of the process steps, as well as any sub-sequence of steps, described with reference to the figure 4 above may be controlled by means of a programmed computer apparatus. Moreover, although the embodiments of the invention described above with reference to the drawings comprise computer apparatus and
processes performed in computer apparatus, the invention thus also extends to computer programs, particularly computer programs on or in a carrier, adapted for putting the invention into practice. The program may be in the form of source code; object code, a code intermediate source and object code such as in partially compiled form, or in any other form suitable for use in the implementation of the process according to the invention. The carrier may be any entity or device capable of carrying the program. For example, the carrier may comprise a storage medium, such as a Flash memory, a ROM (Read Only Memory), for example a CD (Compact Disc) or a semiconductor ROM, an EPROM (Erasable Programmable Read-Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a magnetic recording medium, for example a floppy disc or hard disc. Further, the carrier may be a transmissible carrier such as an electrical or optical signal which may be conveyed via electrical or optical cable or by radio or by other means. When the program is embodied in a signal which may be conveyed directly by a cable or other device or means, the carrier may be constituted by such cable or device or means. Alternatively, the carrier may be an integrated circuit in which the program is embedded, the integrated circuit being adapted for performing, or for use in the performance of, the relevant processes.
The invention is not restricted to the described embodiments in the figures, but may be varied freely within the scope of the claims.
Claims
1 . An exhaust brake system for a motor vehicle, comprising: a first adjustable valve (135) adapted to obstruct the exhaust gasses (Eout) from an internal combustion engine (1 10) of the vehicle in response to a first control signal (C1 ) so as to accomplish a brake-torque during the engine's (1 10) exhaust stroke, a second adjustable valve (107) operable in response to a second control signal (C2) and arranged in a recirculation passa- ge (1 15) connecting an exhaust gas conduit (150) from the engine (1 10) with an air intake (105) to the engine (1 10), a sensor means (155) arranged to register an exhaust gas pressure level (Pm) in the exhaust gas conduit (150) between the engine (1 10) and the first adjustable valve means (135), a turbo unit (160) arranged in the exhaust gas conduit (150) and controllable in response to a third control signal (C3), and a control unit (120) adapted to produce the first control signal (C1 ) in response to a set value (Treq) designating a desired brake-torque, characterized i n that the control unit (120) is ad- apted to: check if the set value (Treq) designates a brake-torque below a first threshold level and the engine (1 10) is controlled to a drive-torque below a second threshold level, and if both these conditions are fulfilled generate the second control signal (C2) such that the second adjustable valve (107) is adjusted to a closed position, generate the third control signal (C3) such that the turbo unit (160) opens up maximally with respect to the exhaust gasses ) test if the exhaust gas pressure level (Pm) exceeds a third threshold level, and if so produce an alarm triggering signal (A) in respect of the first adjustable valve (135).
2. The system according to claim 1 , wherein the first and se- cond threshold levels represent a motoring state in which the engine (1 10) does not propel the vehicle.
3. The system according to any one of the claims 1 or 2, wherein the control unit (120) is adapted to: receive a status signal (mv) indicative of a functionality condition of an actuating means (145, 130) adapted to influence an adjustment of the first adjustable valve (135), test whether or not the status signal (mv) fulfills an alarm criterion, and if so generate the second control signal (C2) such that the second adjustable valve (107) is adjusted to a predetermined posi- tion.
4. The system according to claim 3, wherein the predetermined position represents an adjustment of the second adjustable valve (107) to a fully opened position.
5. The system according to any one of the claims 3 or 4, whe- rein the actuating means comprises: a piston member (130) operative in response to a pressurized fluid (Fp), and a valve means (145) operative in response to the first control signal (C1 ) and adapted to forward the pressurized fluid (FP) to the piston member (130).
6. The system according to any one of the claims 3 to 5, wherein the first control signal (C1 ) is an electric-type of signal, and the status signal (mv) is based on at least one electric parameter associated with an operation of the actuating means (145, 130).
7. The system according to claim 6, wherein the first control signal (C1 ) has a pulse-width-modulation format and the first adjustable valve (135) is adapted to open a passage for the exhaust gasses (Eout) from the engine (1 10) based on a pulse width (PWC) of the first control signal (C1 ).
8. A motor vehicle (200) comprising an internal combustion engine (1 10), characterized i n that the vehicle (200) comprises the exhaust brake system according to any one of the claims 1 to 7, the system being configured to apply an adjustable brake-tor- que with respect to at least one drive axis of the engine (1 10).
9. A method of controlling an exhaust brake in a motor vehicle, wherein a first adjustable valve (135) is adapted to obstruct the exhaust gasses (Eout) from an internal combustion engine (1 10) of the vehicle in response to a first control signal (C1 ) so as to accomplish a brake-torque during the engine's (1 10) exhaust stroke, a second adjustable valve (107) is operable in response to a second control signal (C2) and arranged in a recirculation passage (1 15) connecting an exhaust gas conduit (150) from the engine (1 10) with an air intake (105) to the engine (1 10), a sensor means (155) is arranged to register an exhaust gas pressure level (Pm) in the exhaust gas conduit (150) between the engine (1 10) and the first adjustable valve means (135), and a turbo unit (160) is arranged in the exhaust gas conduit (150) and controllable in response to a third control signal (C3), the method comprising producing the first control signal (C1 ) in response to a set value (Treq) designating a desired brake-torque, characterized by: checking if the set value (Treq) designates a brake-torque below a first threshold level and the engine is controlled to a drive-torque below a second threshold level, and if both these conditions are fulfilled generating the second control signal (C2) such that the second adjustable valve (107) is adjusted to a closed position, generating the third control signal (C3) such that the turbo unit (160) opens up maximally with respect to the exhaust gas¬ testing if the exhaust gas pressure level (Pm) exceeds a third threshold level, and if so producing an alarm triggering signal (A) in respect of the first adjustable valve (135).
10. The method according to claim 9, wherein the first and second threshold levels represent a motoring state in which the engine (1 10) does not propel the vehicle.
1 1 . The method according to any one of the claims 9 or 10, comprising: receiving a status signal (mv) indicative of a functionality condition of an actuating means (145, 130) adapted to influence an adjustment of the first adjustable valve (135), testing whether or not the status signal (mv) fulfills an alarm criterion, and if so generating the second control signal (C2) such that the second adjustable valve (107) is adjusted to a predetermined position.
12. The method according to claim 1 1 , wherein the predetermined position represents an adjustment of the second adjustable valve (107) to a fully opened position.
13. The method according to any one of the claims 1 1 or 12 wherein the first control signal (C1 ) is an electric-type of signal, and the status signal (mv) is based on at least one electric parameter associated with an operation of the actuating means (145, 130).
14. The method according to claim 13, wherein the first control signal (C1 ) has a pulse-width-modulation format and the first adjustable valve (135) is adapted to open a passage for the exhaust gasses (Eout) from the engine (1 10) based on a pulse width (PWC) of the first control signal (C1 ).
15. A computer program product loadable into a memory (125) of a computer included in a motor vehicle (200) which is equipped with an exhaust brake system and an exhaust gas recirculation system, the computer program product comprising software adapted to control the steps of any of the claims 9 to 14 when the program product is run on the computer.
16. The computer program product according to claim 15, wherein the program product is recorded onto a carrier.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE0700761-0 | 2007-03-27 | ||
SE0700761A SE530717C2 (en) | 2007-03-27 | 2007-03-27 | Exhaust Brake Control |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2008118073A1 true WO2008118073A1 (en) | 2008-10-02 |
Family
ID=39684020
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SE2008/050305 WO2008118073A1 (en) | 2007-03-27 | 2008-03-18 | Exhaust gas brake control |
Country Status (2)
Country | Link |
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SE (1) | SE530717C2 (en) |
WO (1) | WO2008118073A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2412954A1 (en) * | 2010-07-26 | 2012-02-01 | MAN Nutzfahrzeuge Österreich AG | Method for braking a motor |
WO2013006540A1 (en) * | 2011-07-06 | 2013-01-10 | Caterpillar Inc. | Control system for engine with exhaust gas recirculation |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6085526A (en) * | 1998-04-01 | 2000-07-11 | Daimlerchrysler Ag | Process and braking arrangement for an exhaust gas turbocharger having a variable turbine geometry |
JP2001280173A (en) * | 2000-03-31 | 2001-10-10 | Nissan Diesel Motor Co Ltd | Auxiliary brake device |
JP2004324417A (en) * | 2003-04-21 | 2004-11-18 | Isuzu Motors Ltd | Exhaust gas recirculation system |
-
2007
- 2007-03-27 SE SE0700761A patent/SE530717C2/en unknown
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2008
- 2008-03-18 WO PCT/SE2008/050305 patent/WO2008118073A1/en active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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US6085526A (en) * | 1998-04-01 | 2000-07-11 | Daimlerchrysler Ag | Process and braking arrangement for an exhaust gas turbocharger having a variable turbine geometry |
JP2001280173A (en) * | 2000-03-31 | 2001-10-10 | Nissan Diesel Motor Co Ltd | Auxiliary brake device |
JP2004324417A (en) * | 2003-04-21 | 2004-11-18 | Isuzu Motors Ltd | Exhaust gas recirculation system |
Non-Patent Citations (1)
Title |
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PATENT ABSTRACTS OF JAPAN * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2412954A1 (en) * | 2010-07-26 | 2012-02-01 | MAN Nutzfahrzeuge Österreich AG | Method for braking a motor |
RU2488010C2 (en) * | 2010-07-26 | 2013-07-20 | МАН Трак унд Бас Эстеррайх АГ | Method of braking by engine |
WO2013006540A1 (en) * | 2011-07-06 | 2013-01-10 | Caterpillar Inc. | Control system for engine with exhaust gas recirculation |
Also Published As
Publication number | Publication date |
---|---|
SE0700761L (en) | 2008-08-19 |
SE530717C2 (en) | 2008-08-19 |
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