WO1997008433A1

WO1997008433A1 - Aspiration system for a reciprocating internal-combustion engine

Info

Publication number: WO1997008433A1
Application number: PCT/DE1996/001593
Authority: WO
Inventors: Marco Herr
Original assignee: Marco Herr
Priority date: 1995-08-30
Filing date: 1996-08-27
Publication date: 1997-03-06
Also published as: AU7281096A; WO1997008434A1; DE19531985A1; CA2271626A1; EP0847484A1; NO981464D0

Abstract

Proposed is an aspiration system for a reciprocating internal-combustion engine with at least one cylinder (4) with several inlet channels (10, 11), each fitted with an inlet valve, and an aspiration tube containing an aspiration channel (13) connected to the inlet channels. The aspiration system is characterized in that the aspiration channel (13) has a separation wall (17) which can be moved, depending on the operation condition of the engine, from a position in which the flow cross-section is reduced to the extend that only one inlet channel (10) is left open into a position in which the flow cross-section is at its maximum, with all the inlet channels (10, 11) open.

Description

Ali suction system for a piston internal combustion engine

The invention relates to an intake system for a piston internal combustion engine according to the preamble of claim 1.

It is known in piston internal combustion engines with two intake valves per cylinder to assign each intake valve its own intake port. In order to generate a high inflow speed with a corresponding charge movement (swirl) in the cylinder at low load and / or low speed, it is known to close one of the inlet channels as a function of the operating point. Such an arrangement is described in MTZ, 1994, number 9, page 519. In this known arrangement, two different inlet channels (primary and secondary channels) are provided for each cylinder, one of which can be closed by means of a flap which is only opened when certain operating states of the internal combustion engine are reached. This does indeed result in better torque in the lower speed range and an improvement in combustion at part load. However, the arrangement is associated with a higher flow resistance and, moreover, the division into a primary channel (small diameter, long length) and a secondary channel (large diameter, shorter length) in the middle and upper speed or. Load range filling losses due to the geometry of the primary channel.

The constant swirl level, which is established by switching off an inlet duct, leads in certain operating states to considerable disadvantages with regard to the thermodynamic efficiency, the pollutant emissions and the charge change.

With increasing load and speed, the centrifugal forces on the hydrocarbon molecules also increase, which leads to a high concentration on the cylinder wall. This results in incomplete combustion and thus an increase in HC emissions.

The rotation of the swirl accelerates the combustion towards the cylinder wall. This leads to an increase in wall heat losses in certain or unfavorable operating points. Furthermore, the generation of the Swirl flow in the intake phase a higher charge exchange work.

From DE 35 18 684 AI an intake manifold for a multi-cytoder internal combustion engine is known, which has only one intake valve per cylinder. The intake ducts leading to the inlet valves each have a wall section which is at least partially elastically adjustable. This ensures that the flow velocity prevailing in the intake manifolds can be adapted to the operating parameters of the internal combustion engine.

From DE 44 12 281 AI an inlet duct system for an internal combustion engine with several inlet ducts per cylinder is known, in each of which an inlet valve works. A rotary slide valve is arranged in one of the inlet ducts, by means of which the gas flow can be throttled and deflected. This is intended to ensure that the charge movement in the cylinder can be adapted to the operating parameters of the internal combustion engine.

The invention has for its object to provide an intake system for Piston Brennl-xaftmaschinen with several intake valves per cylinder, which in addition to high torque at low speeds and good charge movement in the cylinder at part load also in the medium and upper speed range at full load enables a high degree of delivery by vibration tuning.

This object is achieved with an intake system according to claim 1. According to the invention, it can be made into a cylinder

Change the leading intake duct so that, depending on the operating state of the internal combustion engine, only one inlet duct is released, forming a flow path with a cross-section that is reduced in cross section, as a result of which high flow velocities are achieved at low speeds or partial load. The asymmetrical intake via an inlet valve (in the case of a multi-valve engine) additionally creates a swirl flow in the cylinder, which enables high exhaust gas recirculation compatibility and good lean running capability. The partition can assume any position between the minimum and maximum cross-section and thereby also determine the size of the amplitude of the vacuum wave in the intake duct, which has a strong influence on the resonance in the upstream resonance chambers. At full load of the internal combustion engine or high speeds, the partition of the intake duct can be moved into a position in which, with the formation of a flow path with a maximum cross section, are released, that is to say maximum filling and maximum torque are achieved. By throttling the intake mixture in an inlet duct in a multi-valve engine, the charge movement or the swirl level can be controlled so that the disadvantages of the swirl flow mentioned at the beginning are avoided.

The subclaims are directed to advantageous developments and embodiments of the intake system according to the invention.

The invention is explained below with reference to schematic drawings, for example and with further details.

They represent:

1 is a schematic plan view of an intake system according to the invention,

2 shows a cross section along the line II-II through an intake duct of FIG. 1,

3 is a view similar to FIG. 2 with the maximum cross section of the intake duct,

4 shows a schematic view of a pneumatically operating system for adjusting the intake duct cross section,

5 is a block diagram of the entire intake system according to the invention,

6 is a plan view of an intake system modified compared to FIG. 1,

7 is a plan view of a further intake system, modified compared to FIG. 1,

Fig. 8 is a modified compared to Fig. 1 intake system on a

Four-cylinder engine,

9 is a sectional view of the plane DC-IX in Fig. 8, Fig. 10 is an enlarged sectional view. 8 with two different functional states,

11 is a side view and top view of a stationary component delimiting the intake ducts,

12 is a side view and top view of a movable component delimiting the intake ducts,

Fig. 13 views of the fixed and the movable component acc. 11 and 12, seen perpendicular to the axis of the intake channels,

14 shows the system structure of an electronic intake cross section control,

15 is a view of the intake system with the drive unit, viewed in the direction of the intake ducts,

16 is a view of the arrangement according to FIG. Fig. 15, seen perpendicular to the intake channels and

Fig. 17 is a plan view of a modified channel guide compared to FIG. 10.

1, an internal combustion engine working with reciprocating pistons in the example shown has six cylinders 4, each having two exhaust valves 6 and two intake valves 8 and 9. An inlet duct 10 or 11 runs inside the cylinder head to each intake valve 8 or 9.

The two inlet channels 10 and 11 assigned to each cylinder 4 each open into an intake channel 13, which connects them to a resonance chamber 15 of an intake device 17 which is known per se.

Provided in each of the intake ducts 13 along the length thereof is a movable dividing wall 17, shown in dashed lines in FIG. 1, which is movable in the direction of the double arrow 19 such that the intake duct 11 assigned to the intake valve 9 is optional is closed or open. For this purpose, the partition 17 has at its end belonging to the inlet channel 11 and preferably also at its end assigned to the resonance chamber 15 a closing surface which closes or releases the corresponding opening cross sections. When the partition 17 is in the position shown in dashed lines in FIG. 1, only the inlet duct 10 is released and the intake duct 13 has a cross section corresponding to approximately half of its maximum value. If the partition 17 is moved to the right as shown in FIG. 1, the intake duct 13 has a maximum cross section and completely clears the inlet duct 11.

A flap 19 is provided in the resonance chamber 15, by means of which the resonance chamber 15 can be divided into two individual chambers 21 and 23. From each of the chambers 21 and 23, a suction pipe 25 and 27 leads to a throttle valve part, in which a throttle valve 29 is arranged for controlling the power of the internal combustion engine.

Fig. 2 shows the structure of the intake duct 13 in more detail. The intake duct 13 comprises a rigid component 31, which is exemplary U-shaped in cross section, the legs 33 and 35 of which also receive a slide 37, which is also U-shaped in cross section, the base of which forms the movable partition 17.

The slide 37 is provided at the free ends of its legs with outward flanges 39 and 41, which together with correspondingly designed parts of a housing 47, which is rigidly connected to the component 31, form piston-cylinder units 49 to 51, the interior of which by displacement of the slide 37 changed relative to the component 31 or housing 47 in volume. It is understood that suitable seals are provided between the flanges 39 and 41 or the slide 37 and the rigid components.

One or more sleeves 43 and 45 are provided along the length of the flanges 39 and 41, respectively, which serve to hold helical compression springs 53 which urge the slide 37 according to FIG. 2 to the right.

For better guidance of the slide 37, the housing 47 has a projecting guide projection 57 which projects into the slide 37. In the position of the slide 37 shown in FIG. 2, the intake duct 13 has a minimum cross section Qi, whereas in the position shown in FIG. 3 the cross section Q2 of the intake duct 13 is maximum. The slide 37 is adjusted by applying more or less negative pressure to the interior of the piston-cylinder units 49 and 51 via the vacuum lines 55. If there is no negative pressure, the slide 37 is moved by the coil springs 53 into the position according to FIG. 3. At maximum negative pressure, the force of the coil springs 53 is overcome and the slide 37 is moved into its position according to FIG. 2.

To compensate for pressure, the housing 47 is provided with ventilation holes 59.

It goes without saying that the slide 37 is provided on its end faces (according to FIG. 1) at the top and bottom with closing surfaces which close the respective cross sections of the inlet channel 11 or the connection openings of the resonance chamber 15.

4 shows the device for controlling the vacuum lines 55:

A vacuum accumulator 59 is connected via a check valve 60 to the resonance chamber 15, which, arranged downstream of the throttle valve 29, is under partial pressure under partial load. The vacuum accumulator 59 is connected to a distribution chamber 64 from which the vacuum lines 55 originate via an electromagnetic 3/2-way valve 63 controlled by an electronic control unit 61. In the event that insufficient vacuum is not available in the vacuum reservoir 59, a vacuum pump 66 is provided which is switched on by a pressure manometer 68.

The structure of the control unit 61 results from the schematic illustration according to FIG. 5. The control unit 61 contains a microprocessor 70 and an input module 72 for the microprocessor 70. The engine speed 80, the position 81 of the throttle valve 29, the air temperature 82 are preferably used as input variables , the operating temperature 83 of the internal combustion engine, for example the water or oil temperature, the output signal of a knock sensor 84 and the position 85 of the movable partition 17 and, if appropriate, further operating parameters. From these input variables, the microprocessor 70 calculates the optimal position of the partition 17, which, for example, had previously been carried out in the microprocessor by empirical tests in the manner of a map was entered. Another output of the control device 61 controls the position of the movable flap 19 within the resonance chamber 15.

The function of the arrangement described is as follows:

In a lower speed range or with a lower partial load (largely closed throttle valve 29), the distribution chamber 64 is actuated by the control unit 61 via the 3/2-way valve 63, subjected to maximum negative pressure, so that the partition 17 in the position according to FIG 2 is located, ie the cross section of the intake ducts 13 is minimal. In addition, the flap 19 is closed. By reducing the intake cross-section in the lower speed range, the prevailing flow speed increases, resulting in an intensive charge movement in the cylinders, which offers good conditions for thermodynamic combustion. The swirl flow generated in the combustion chamber also enables good lean running and high exhaust gas recirculation rates. In the lower to medium speed range, the position of the flap 19 is largely retained, even if the throttle valve 29 is partially opened, which leads to a resonance in the chambers 15 and increases the degree of delivery or the torque of the internal combustion engine.

With increasing opening of the throttle valve and increasing speed of the internal combustion engine, the partition 17 moves with decreasing negative pressure under the influence of the force of the coil springs 53 into the position according to FIG. 3. Maximum flow cross-sections are achieved using all inlet valves, i.e. optimal filling and torques achieved.

Thus, while all the intake valves are fully effective in the full-load range at high speeds, only one intake valve is effective in the partial-load range, which enables the charge movement in the combustion chamber.

The embodiment shown in FIG. 6 differs from that of FIG. 1 in that a further flap 87 is arranged between the two suction pipes 25 and 27, which additionally supports the resonance behavior.

In the lower speed range, both flaps 19 and 87 are closed. In the middle The flap 19 remains closed in the speed range and the flap 87 is opened. In the upper speed range, both flaps 19 and 87 are opened. The position of the movable partition 17, like that of the flaps 19 and 87, is controlled by the control device 61.

Fig. 7 shows a further use of the variable intake pipes 13 using the example of a 4-cylinder in-line engine. In order to better adapt the vibration behavior or resonance behavior of the intake system to the operating parameters of the internal combustion engine, individual volumes V2 and V3 are connected to the volume of the resonance chamber 15 by means of flaps 88 and 89 in the manner of a Helmholtz resonator. The flaps 88 and 89 are controlled via the control unit 61. At low speeds, the flaps 88 and 89 remain open and, with increasing speed, flap 89 and then 88 are closed.

It goes without saying that numerous modifications of the described embodiment of the invention are possible:

For example, the displacement of the slide 37 can be controlled by an electric motor, hydraulically or by other drive devices.

The cross section of the intake duct can also be changed by a wall which is movable in it and which is flexible in itself and, for example, is filled with fluid depending on the operating point, components attached to it and provided with a closing surface increasingly closing the inlet ducts or outlet openings of the resonance chamber.

FIG. 8 shows an embodiment similar to that of FIG. 7, the same reference numerals being used in the figure for corresponding parts as in the previous figures. Difference to the embodiment acc. Fig. 7 are that the flap 89 is missing and only a volume in the manner of a Helmholtz resonator is switched to the volume of the resonance chamber 15 and that the inlet channels 10, 11 are not guided separately up to the end face of the cylinder head 90, so that the movable partition wall 17 protrudes into the cylinder head 90.

The construction of the movable partition 17 is modified accordingly, as will be explained below. FIG. 9 shows a section in the plane IX-IX of FIG. 8, the intake duct 13 having the maximum cross section being shown in FIG. 9 and the minimum cross section being shown below. This is achieved by moving the movable partition 17, the construction of which can be seen in FIGS. 10 to 13.

Overall, all the intake ducts 13 and their cross-section variability are formed by two components 100 and 102 which can be displaced relative to one another, the component 100 being rigidly connected to the cylinder head in a manner fixed to the engine and in turn the resonance chamber 15 being fastened to it. The component 102 is displaceably guided on the component 100 and is formed with the movable partition walls 17.

The stationary component 100 is formed with channels 104 (FIGS. 9 and 11), the cross sections of which are formed with an oversize compared to the maximum cross sections of the suction channels 13, so that they additionally accommodate the movable partition walls 17 formed on the component 102. In this case, the stationary component 100 between the cylinder head 90 and a separating or guide plane 106 is designed as a solid block, from which webs 108 project towards the resonance chamber or the intake manifold, which form part of the inner wall of the intake ducts 13 and their free ends Attach the wall 110 of the resonance chamber.

Movable component 102 is generally complementary to stationary component 100, i.e. is formed overall between the plane 106 and the wall 110 in a block-like manner with through channels 111 which form part of the inner wall of the intake channels 13 and accommodate the webs 108. Long webs 112 and short webs 114 protrude from the block-like region of component 102, at the ends of which are each parallel to

Parting plane 106 extending flanges 116 and 118 are formed. The flanges 116 engage in corresponding recesses in the cylinder head 90. The flanges 118 engage behind the wall 110 of the resonance chamber. Thus, the flanges 116 and 118, which serve primarily as sealing surfaces for the resonance chamber and the inlet channel, form an additional guide for the component 102.

The basic guidance of the component 102 on the component 100 takes place by means of dovetail guides 122 (FIGS. 11 and 13) and 124 (FIGS. 12 and 13) formed on the parting and guide plane 106 and a strip 125. The assembly of the arrangement described is such that the component 100 is attached to the cylinder head 90. Subsequently, the component 100 with the webs 112 is inserted into the channels 104 of the component 100 until the flanges 116 protrude into the recesses 120 in the cylinder head. Thereafter, the strip 125 is inserted into the guides 122 and 124, so that the dovetail guide is provided overall. The strip 125 is preferably secured with set screws on the component 122 against displacement. The resonance chamber is then connected to the webs of component 100.

10, on the left, shows the component 102 fully inserted laterally into the component 100, the intake duct 13 having a maximum cross section. 10, right, shows the component 102 pushed out laterally from the component 100 in a position in which the inlet channel 11 is closed to the inlet valve 9.

It goes without saying that, when the component 102 is displaced, changing cavities are provided with ventilation bores, not shown. The shifting surfaces between the components 100 and 102 are sealed against one another, so that the intake duct 13 is reliably sealed in every operating state.

14 schematically shows the system structure of the electronic control with sensors 126, which record the individually entered operating states of the internal combustion engine and send them to a control unit 128, which evaluates the sensed values and converts them into control values under control by means of a microprocessor, corresponding to an actuating unit 130 for Moving the movable component 102 and a further actuating unit 132 for the flap 88 and possibly other flaps can be controlled.

15 and 16 show the basic structure of the drive device for the movable component 102 using an electric motor as an example:

The control unit 128 controls an electronic control system 134, which supplies an actuating signal for an electric motor 136 fixed to the internal combustion engine, the pinion 138 of which meshes with a toothed rack 140 which is rigidly connected to the movable component 102. The function of the embodiment acc. 8 to 16 corresponds to that described above. The flap 88 remains open at a low speed and closes with increasing speed, as a result of which the resonance behavior of the suction system adapts to the operating parameters. The movable component 102 is moved under control by means of the control device 128 and stored therein, possibly empirically determined characteristic maps, the input variables of which are the operating parameters detected by the sensors 126, into the position in which the intake duct 13 each corresponds to the operating behavior of the internal combustion engine optimal cross-section. All intake valves 8 and 9 are fully effective in the full-load range at high speeds, whereas only one of the intake valves is fully effective in the partial-load range.

17 shows the intake system according to the invention using the example of a diesel engine with two different intake ducts, the constantly fully effective intake duct 10 being designed as a swirl duct and the intake duct 11 being designed as a filler duct which can be throttled by reducing the cross section of the intake duct 13 (right-hand one Half of the figure).

Claims

claims

1. Intake system for a piston internal combustion engine with at least one cylinder (4) with a plurality of inlet channels (10, 11), in each of which an inlet valve works, and an intake manifold with an inlet channel (13) connected to the inlet channels, characterized in that the inlet channel (13) has a partition (17) which is movable as a function of the operating state of the internal combustion engine and which can be moved from a position in which only one inlet duct (10) is released to form a flow path with a reduced cross section, into a position in which to form of a maximum flow path in cross section, all inlet channels (10, 11) are released.

2. Intake system according to claim 1, characterized in that the intake duct (13) has a cross-sectionally U-shaped rigid component (31), the

Leg (33,35) an the open side of the U-closing, on the inner walls of the

Leg-guided, the partition (17) containing slide (37), by moving the cross section of the intake duct can be changed.

3. Intake system according to claim 2, characterized in that the slide (37) to the inlet channels (10, 11) and / or to the resonance chamber (15) is formed with a closing surface.

4. Intake system according to claim 2 or 3, characterized in that the cross-sectionally U-shaped, rigid

Component (31) is accommodated in a housing (47), and that the slide (37) has flanges (39, 41) projecting outside the U, which together with the housing piston-cylinder units (49, 51) for moving the slide form.

5. Intake system according to claim 4, characterized in that the slide (37) has a U-shaped cross section and in the housing (47) a guide projection (57) is provided which protrudes into the U-shaped cross section of the slide.

6. Intake system according to one of claims 1 to 5, characterized in that a pneumatically operating, by an electronic control device (61) controlled drive device (59,63,55) is provided for moving the partition (17).

7. Intake system according to claim 1, characterized in that the intake duct (13) between a machine-fixed component (100) and a relatively to this displaceable component (102) is formed, wherein the machine-fixed component and the displaceable component are designed complementary to each other and Each have a block-like area with a through-channel (104, 111) and a web (108, 112), the web of one component projecting through the through-channel of the other component and the suction channel being delimited by the webs and the through-channels.

8. Intake system according to claim 7, characterized in that the internal combustion engine is multi-cylinder and all intake channels (13) through through channels (104, 111) and webs (108, 112) on the machine-fixed component (100) and the component which is displaceable relative to this ( 102) (are formed.

9. Intake system according to claim 7 or 8, characterized in that a dovetail guide (122, 124) is provided between the machine-fixed component (100) and the displaceable component (102).

10. A suction system according to one of claims 7 to 9, characterized in that the displaceable component (102) with a bottle (116) formed at the free end of its web (112) in a corresponding recess formed in the cylinder head (90) of the internal combustion engine ( 120) intervenes.

11. Intake system according to one of claims 7 to 10, characterized in that the displaceable component (102) with a flange (118) has a wall (110) of the intake pipe (resonance chamber 15) spreads.

12. Intake system according to one of claims 7 to 11, characterized in that the displaceable component has a toothed rack (140) into which a pinion (138) of a machine-fixed electric motor (136) engages.

13. Intake system according to one of claims 1 to 12, characterized in that the internal combustion engine is multi-cylinder and the leading to the individual cylinders, their cross-section changeable

Intake channels (13) emanate from a resonance chamber (15), the volume of which can be divided into two chambers (21, 23) by means of a flap (19), the flap (19) in the

Full load range is open at high speeds.

14. Intake system according to claim 13, characterized in that between two intake pipes (25, 27), each of which connects one of the chambers (21, 23) with a throttle valve part (29) for controlling the power of the juicing machine, one by means of a further flap (87) closable connecting channel is arranged, the further flap (87) being open in the middle and upper speed range.

15. Intake system according to one of claims 1 to 12, characterized in that the cross-section changeable

Intake ducts (13) emanate from a resonance chamber (15) with a volume VI, to which a further chamber with a volume V2 connects, with lower ones

Speeds a flap (88) between the volumes VI and V2 is open and closes with increasing speed.

16. Intake system according to claim 15, characterized in that two further chambers with a volume V2 or V3 connect to the resonance chamber (15) with the volume VI in succession, with flaps (88, 89) between the volumes VI and at low speeds V2 and V2 and V3 are open and with increasing speed the flap (89) between V2 and V3 and then the flap (88) between VI and V2 closes.