Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D17/00—Controlling engines by cutting out individual cylinders; Rendering engines inoperative or idling
  • F02D17/02—Cutting-out

Definitions

• the present invention relates to a method and an arrangement which are intended to be used to suppress vibrations which occur in a vehicle due to imbalances in an engine in the vehicle.
• one or more of the cylinders can be switched from normal combustion in order to temporarily be used for other purposes, such as for example an air compressor to fill compressed air tanks in a vehicle, which would replace a separate compressor.
• the compressor function is achieved by a cylinder room which can be connected to the compressed air tanks. This connection is closed during normal operation, and is opened when the cylinder is to be used as a compressor.
• fuel supply to their corresponding cylinder space is cut off.
• the pressure curve in the cylinder will have substantially different characteristics as compared to when the cylinder is used for conventional operation.
• each cylinder has a compression stroke and an expansion stroke.
• the object of the present invention is to create a method and an arrangement which suppresses vibrations which are generated by an engine in which one or more cylinders are used for another purpose than combustion, in order to reduce disturbing vibrations in the surroundings of the engine such as a connected driving rope and/or driving- compartment.
• Fig. 1 schematically shows a part of a cargo vehicle which is equipped with an arrangement according to the invention
• Fig. 2 schematically shows an internal combustion engine which is equipped with a fuel unit of an arrangement according to the invention
• Fig. 3 with a diagram shows torque variations during different operational conditions
• Figs. 4-7 with different vector diagrams show the torque created during different operational conditions
• Fig. 8 shows a diagram of sensitivity for vibrational disturbances.
• EMBODIMENTS Even during normal operation, a conventional internal combustion engine, for example a piston engine in a motor vehicle, generates a torque which varies with the revolution of the crankshaft. This is due to the fact that each cylinder during one or several, usually two revolutions, goes through different strokes at different angles of the crankshaft for different cylinders, with i.a. a compression stroke which consumes energy and thus affects the crankshaft with a negative torque, and an expansion stroke which supplies power to the piston, and thus causes a positive torque on the crankshaft.
• the invention relates to internal combustion engines which are arranged to enable the switching of one or more of the engine cylinders to an alternative operational condition, for example as air compressor by blocking the supply of fuel and thus only supplying air, wherein the outlet is switched to feed compressed air to a compressed air reservoir which is used to supply equipment in the vehicle which is driven by compressed air, for example the brake system. As mentioned initially, this changes the expansion stroke, thus changing the torque variation during the revolution of the crankshaft of the switched cylinder or cylinders.
• the change in torque is counteracted by changing the torque-curve during revolution of the remaining (at least two) cylinders, which are in normal operational condition in such a way that the imbalance caused by switching the operational state of the remaining cylinders is compensated for, which is achieved by differentiating the amount of fuel supplied to the driving cylinders, i.e. each cylinder is given a specifically chosen amount or proportion of fuel.
• the differentiation of the fuel amount is done as a percentual differentiation and/or a calculation of the absolute amount of fuel per cylinder and revolution, based on an unambiguous correlation between the total amount of fuel per combustion and the desired average torque of the crankshaft.
• the control system for control of the differentiated fuel supply can either be an open control system with a control unit which has a large amount of stored data which describes the individual amount of fuel for each cylinder for different operational conditions, such as RPM and load level of the engine, which have been arrived at through a combination of calculations and simulations, so-called “mapping”, or an adaptive control system with sensors which detect vibrations in the vehicle, and which via the control unit control the differentiated fuel supply.
• Fig. 1 very schematically shows the two control systems and shows a part of a truck 1 equipped with an internal combustion engine 2.
• the engine is an internal combustion engine, and of the multi-cylinder piston type engine, as schematically shown in a top-view in Fig. 2.
• the engine is further of the kind which has a discontinuous combustion curve, and thus a torque for each cylinder which varies during revolution.
• the piston engine is of the kind with pistons which move back and forth, and which in the shown example has six combustion units, i.e. cylinders 3-8.
• the engine has a crankshaft which is common for all the cylinders with a conventional crank shaft angle sequence so that the torque additions for the cylinders will occur with an angular displacement between them, causing the resulting torque on the crankshaft, and thus the outgoing shaft to be as smooth as possible during a revolution.
• At least one of the cylinders in the example shown the fifth cylinder 7 as counted from the front, is switchable between a normal operational state to an alternative state in which the cylinder 7 no longer serves as driving unit for propelling the vehicle, but is used as a load, driven by the remaining driving units, for example as an air compressor for driving compressed air driven auxiliary systems in the vehicle, for example the brake system.
• the fuel inlet 38 of the cylinder 7 in question is arranged to be closed completely when switching to this alternative state.
• the fuel inlet 38 can alternatively be open to a certain extent.
• the ignition in cylinder 7 is here switched off, to let unused fuel pass through to the catalyzer. Furthermore, the cylinder, apart from its exhaust outlet 11, is equipped with a compressed air outlet 12 which, by means of a not shown valve can be opened, and which is connected to a not shown compressed air reservoir.
• this alternative state causes imbalances in the engine if no special measures are taken to compensate the change in torque which is caused in the cylinder 7 during revolution of the engine.
• a control system which differentiates, i.e. individually distributes the amount of fuel to each of the cylinders 3-6, 8, which are working in a normal operational state.
• the vehicle is equipped with a control system 15 which can either be central or decentralized.
• a decentralized control system can, e.g. as in the example here shown, consist of two control units, one car control unit 16a and an engine control unit 16b.
• the car control unit 16a is intended to mainly process signals from/to chassis and driving compartment, while the engine control unit 16b is intended to mainly give output data to control the fuel system of the engine.
• the control system can, as mentioned above, either be an open control system or a closed, adaptive control system.
• the open control system has a large amount of stored data, based on a large amount of tests during different operational states, during which measurement of vibration modes in the driving compartment are carried out.
• the car control system 15a has an input 17 which receives an in-signal regarding the current amount of gas, i.e. is arranged to sense the position of the gas pedal 17 in order to thereby give control instruction regarding desired torque on the outgoing shaft 9 of the engine.
• a further control input 18 is arranged to, to the car control unit 16a feed a control signal which indicates the air pressure in a compressed air reservoir 19, and thus the need for compressed air in order to control the switching between a normal operational state of the cylinder 7, and an alternative operational state to generate compressed air.
• a third control input 20 which is indicated with lines and dots, and which is arranged to, to the car control unit 16a feed a control signal from a vibration sensor 21 in the driving compartment 14, which thus creates a direct feedback of vibrations which occur in the driving compartment and which are to be suppressed with the control system according to the invention.
• Examples of other control parameters are RPM, vehicle speed, gear, etc.
• the engine control unit 16b is connected to the car control unit 16a with bi-directional communication, and is arranged to transfer control signals from the car control unit 16a on an input 22 to control instructions on a number of outputs 23-29 for differentiation, i.e. distribution of the amount of fuel to the cylinders 3-6, 8, which are in a normal operational state, and for controlling the switchable cylinder 7 between its two operational states.
• Fig. 3 with a diagram shows torque variations during two revolutions of the crankshaft in a diesel engine, which is the necessary amount in order for each cylinder in a six- cylinder diesel engine to go through all strokes.
• Curve 51 shows an essentially sine-shaped, regular third order torque curve in a normal operational state of all the six cylinders, while curve 52 shows a state where EAC (Engine Air Compressor) is activated, see patent number 467 503, i.e. the fifth cylinder 7 is in a compressor state, whereby the torque is raised when the crankshaft is at certain angles.
• EAC Engine Air Compressor
• Curves 53 and 54 show a state according to the invention where differentiated amounts of fuel have caused an increased torque at certain angles of the crankshaft, with the amounts of fuel chosen so that 0.5th order vibrations have been suppressed, see curve 53, and 0.5th and 1.5th order vibrations have been suppressed, see curve 54 which will be discussed in detail below.
• Fig. 5 shows that vibrations are caused at 0.5th and 1.0, 1.5th and 3.0 order vibrations, which thus in practice causes a very noticeable transmission of vibrations to the driving compartment.
• Fig. 7 shows an operational state with such a differentiation of fuel amount that the following orders are suppressed.
• Fig. 7a shows 0.5th order vibrations which are relatively well suppressed.
• Fig. 7b shows 1.0 order vibrations which are not suppressed.
• Fig. 7c shows 1.5th order vibrations which are relatively well suppressed, while finally Fig. 7d shows 3.0 order vibration mood which is suppressed to a relatively limited extent.
• Fig. 8 shows the effect of different vibrational frequencies due to for example the natural frequency of the chassis. From this it can be seen that the effect varies greatly with the frequency, which forms the base for choosing suppression of certain orders of vibration. Those orders which cause large amplitudes of vibration in the surrounding parts of the vehicle are given priority, as opposed to those orders which cause small amplitudes.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Control Of Vehicle Engines Or Engines For Specific Uses (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)

Priority Applications (6)

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Publications (1)

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ID=20400684

Family Applications (1)

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Cited By (2)

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Citations (3)

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• 1995
  • 1995-12-22 SE SE9504603A patent/SE512556C2/sv not_active IP Right Cessation
• 1996
  • 1996-12-20 JP JP52358797A patent/JP4414489B2/ja not_active Expired - Lifetime
  • 1996-12-20 BR BR9612211A patent/BR9612211A/pt not_active IP Right Cessation
  • 1996-12-20 US US09/091,585 patent/US6247449B1/en not_active Expired - Lifetime
  • 1996-12-20 DE DE69629126T patent/DE69629126T2/de not_active Expired - Lifetime
  • 1996-12-20 EP EP96944168A patent/EP0868601B1/en not_active Expired - Lifetime
  • 1996-12-20 AU AU14037/97A patent/AU1403797A/en not_active Abandoned
  • 1996-12-20 WO PCT/SE1996/001745 patent/WO1997023716A1/en active IP Right Grant

Patent Citations (3)

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