AU7281096A

AU7281096A - Inlet system for a piston internal combustion engine

Info

Publication number: AU7281096A
Application number: AU72810/96A
Authority: AU
Inventors: Marco Herr
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-08-30
Filing date: 1996-08-14
Publication date: 1997-03-19
Also published as: NO981464D0; WO1997008434A1; EP0847484A1; WO1997008433A1; DE19531985A1; CA2271626A1

Description

WO 97/08434 PCT/EP96/03586 Intake System for Internal Combustion Engine The invention relates to an intake system for an internal combustion engine according to the preamble of claim 1. It is know that in internal combustion engines with two inlet valves per cylinder, 5 a separate inlet channel is provided for each inlet valve. To generate a high admission rate a low load and/or low rpm with a corresponding charge movement (swirl) in the cylinder, it is known that one of the inlet channels can be closed as a function of the operating point. One such arrangement is described in MTZ, 1994, vol. 9, page 519. With this known arrangement, two different inlet 10 channels primary and secondary channels are provided per cylinder, one of which can be closed by means of a valve which is opened only when the engine reaches certain operating states. Altough a better torque is achieved in the lower rpm range and an improvement in combustion at underload is achieved, this arrangement is associated with a greater flow resistance, and furthermore, the 15 division into a primary channel (small diameter, large length) and a secondary channel ( large diameter, shorter length) yields filling losses in the middle and upper rpm and load ranges due to the geometry of the primary channel. German Patent DE 3, 518 , 684 Al discloses an intake tube for a multicylinder 20 combustion engine which has only one inlet valve per cylinder. The intake channels leading to the inlet valves each have a wall section which is designed to be at least partially elastically adjustable. This achieves the result that the velocity of flow prevailing in the intake tubes can be adapted to the operating parameters of the combustion engine. 25 German Patent DE 4,412,281 Al discloses an inlet channel system for a combustion engine with several inlet channels per cylinder, with one inlet valve working in each. In one of the inlet channels is arranged a rotary slide valve by means of which the gas flow can be throttled and deflected. Consequently, it 30 should be possible to adapt the charge movement in the cylinder to the operating parameters of the combustion engine. An intake system in accordance with the characterising portion of the enclosed Claim 1 is known from DE 40 17 066 Al, whereby a throttle valve operates in 35 one of two inlet channels belonging to a cylinder and only outer inlet channel of the inlet channels provided with the partition is clear when this throttle valve is in closed state. At partial load, the valve is brought into this position, in which a WO 97/08434 PCT/EP 96/03586 2 swirling inflow into the combustion chamber is achieved. At full load the valve is completely open, as a result of which the cross-sections of both inlet channels are fully utilised and no swirling takes place. A characteristic of this configuration is that when the throttle valve is not fully open it produces a substantial flow from 5 the intake tube into the inlet channels, which are very short because they are installed within the cylinder head, and this results in swirling and has an unfavourable effect on flow resistance. There is no provision for the intake tube located in the intake channel to be employed to balance the oscillation processes. 10 The present invention is based on the task of creating an intake system for a reciprocating piston internal combustion engine incorporating several inlet valves per cylinder which, in addition to enabling high torque at low speeds and optimum charging motion in the cylinder at partial load, also permits a high level of volumetric efficiency at full load, by means of oscillation balancing. :15 The objekt is achieved with an intake system according to claim 1. According to this invention, the intake channel leading to a cylinder of an internal combustion engine can be modified so that , depending on the operating state of the combustion engine, forming a flow path with a reduced cross section, only one 20 inlet channel is released, so that high flow velocities are achieved at a low rpm or at underload . Due to the asymmetrical intake through one inlet valve (in a multivalve engine), a swirl flow also develops in the cylinder, permitting a high exhaust gas recycling tolerability and a good lean running capability. The parition may assume any position between minimal and maximum cross section and thus 25 can also determine the size of the amplitude of the reduced pressure wave in the intake channel which has a great influence on the resonance in the resonant spaces upstream of the intake channel. At full load the combustion engine or a high rpm, the partition of the intake channel may be moved into a position in which all the inlet channels are released, forming a flow path with the maximum 30 cross section, i. e., maximum filling and maximum torque are achieved. By throttling the intake mixture in a inlet channel in a multivalve engine, the charge movment or swirl level can be controlled in such a way as to avoid the disadvantages of swirl flow mentioned above. By throttling the intake mixture in an admission port on a multi-valve engine, the 35 charging motion and the turbulence swirl can be controlled so as to achieve the necessary charging motion with the lowest possible flow losses in every operational state.

WO 97/08434 PCT/EP 96/03586 3 The subclaims are based on advantageous embodiments and refinements of the intake system according to this invention. 5 This invention is explained below on the basis of schematic diagrams as examples and with additional details. They show: 10 Figure 1: a schematic top view of an intake system according to this invention; Figure 2: a cross section along line I-11 thought an intake channel from Figure 1; 15 Figure 3: a view similar to that in Figure 1 with a maximum cross section of the intake channel; Figure 4: a schematic view of a pneumatic system for adjusting the cross section of the intake channel; 20 Figure 5: a block diagram of the entire intake system according to this invention; Figure 6: a top view of an intake system modified in comparison with Figure 1; 25 Figure 7: a top view of another intake system modified in comparsion with Figure 1; According to Figure 1, a combustion engine working with reciprocating pistons 30 in the example shown here has six cylinders 4, each of which has two exhaust valves 6 and two inlet valves 8 and 9 . Within the cylinder head, an inlet channel 10 or 11 runs to each inlet valve 8 or 9. The two inlet channels 10 and 11 provided for each cylinder 4 open into one intake channels 13 which connects them with an essentially know resonance 35 chamber 15 of an intake device 17. In each of the intake channels 13, a movable partition 17 (shown with dotted lines in Figure 1) is provided along its length and is movable in the direction of double arrow 19 so that the inlet channel 11 provided for the inlet valve 9 is 40 optionally either closed or open. Therefore, on its end belonging to inlet channel WO 97/08434 PCT/EP 96/03586 4 11 and preferably also on ist end belonging to the resonance chamber 15 partition 17 has a closing face which closes or releases the corresponding opening cross sections. If the partition 17 is in the position indicated with dotted lines in Figure 1, only the inlet channel 10 is released and intake channel 13 has a 5 cross section corresponding approximately to half its maximum value. If partition 17 according to Figure 1 is moved completely to the right, intake channel 13 has a maximum cross section and completely releases inlet channel 11. A valve 19 is provided in resonance chamber 15, dividing resonance chamber 15 10 into two individual chambers 21 and 23. An intake tube 25 and 27 leads from each chamber 21 and 23 to a throttle valve part in which is arranged a throttle valve 29 to control the power of the combustion engine. Figure 2 shows the design of intake channel 13 in greater detail. Intake channel 15 13 comprises a rigid part 31, which is shown with an overall U-shaped cross section, and its legs 33 and 35 accommodate a slide valve 37 which also has a U shaped cross section and its base forms the movable partition 17. On the free ends, slide valve 37 has flanges 39 and 41 that face upward and together with correspondingly designed parts of a housing 47, which is rigidly 20 connected to part 31, it forms piston-cylinder units 49 to 51, whose interiors undergo changes in volume due to displacement of slide valve 37 relative to part 31 or housing 47. It is self-evident that suitable seals are provided between flanges 39 and 41 or slide valve 37 and the rigit parts. 25 Along the length of flange 39 or 41, one or more bushings 43 and 45 are provided, which serve to hold helical compression springs 53 which push the slide valve 37 according to Figure 2 toward the right. 30 For better guidance of slide valve 37, housing 47 has a projecting half dog 57 which projects into slide valve 37. In the position of slide valve 37 shown in Figure 2, intake channel 13 has a minimum cross section Qi, whereas in the position according to Figure 3 the 35 cross section Q2 of intake channel 13 is at its maximum. Slide valve 37 is adjusted by a more or less strong vacuum acting on the interior of the piston cylinder units 49 and 51 through vacuum lines 55. If there is no vacuum, slide valve 37 is moved by helical springs 53 into the position according to Figure 3.

WO 97/08434 PCT/EP 96/03586 5 At the maximum vacuum, the force of the helical springs 53 is overcome, and slide valve 37 is moved into its position according to Figure 2. Housing 47 is provided with vent holes 59 for equalization of pressure. 5 It is self-evident that slide valve 37 is provided with closing faces at the top and bottom of its end faces (according to Figure 1) to close the respective cross sections of the inlet channel 11 or the connecting openings of resonance chamber 15. 10 Figure 4 shows the device for controlling the vacuum lines 55: A vacuum storage device 59 is connected by a return valve 60 to the resonance chamber 15 which is arranged downstream of throttle valve 29 and is under a 15 reduced pressure at underload. Vacuum storage device 59 is connected to a distributor chamber 64, with the vacuum lines 55 leading away from it, by way of a 3/2-way electromagnetic valve 63 controlled by an electronic controller 61. For the case when an inadequate vacuum is available in vacuum storage device 20 59, a vacuum pump 66 is provided and is switched on by a pressure manometer 68. The design of controller 61 is shown in the schematic diagram in Figure 5. Controller 61 contains a microprocessor 70 and an input module 72 for 25 microprocessor 70. The input parameters are preferably the engine rpm 80, the setting 81 of the throttle valve 29, the air temperature 82, the operating temperature 83 of the combustion engine, e.g., the water temperature or the oil temperature, the output signal of a knock sensor 84 and the position 85 of the movable partition 17 as well as optionally additional operating parameters. From 30 these input parameters, microprocessor 70 computes the optimum position of partition 17, which was previously entered into the microprocessor in the form of an engine characteristics map based on empirical tests. Another output of controller 61 controls the position of the movable valve 19 within the resonance chamber 15. 35 The arrangement described her functions as follows: WO 97/08434 PCT/EP 96/03586 6 In a lower rpm range or at a lower underload (throttle valve 29 mostly closed), a maximum vacuum acts on distributor chamber 64, which is driven by controller 61 by way of the 3/2-way valve 63, so that partition 17 is in the position according to Figure 2, i. e., the cross section of the intake channels 13 is minimal. 5 In addition, valve 19 is closed. Due to the reduction in intake cross section in the lower rpm range, the velocity of flow prevailing there is increased, so that an intense charge movement prevails in the cylinders, offering good prerequisites for thermodynamic combustion. The swirl flow prevailing in the combustion chamber also permits good lean running capability and high exhaust gas 10 recycling levels. In the lower to middle rpm range, the position of valve 19 remains largely the same, although throttle valve 29 is partially opened, which leads to a resonance in chamber 15 and increases the charging efficiency and the torque of the combustion engine. :15 With increasing opening of the throttle valve and increasing rpm of the combustion engine, partition 17 moves into the position according to Figure 3 with diminishing vacuum under the influence of the force of helical springs 53. Maximum flow cross sections are achieved, utilizing all inlet valves, i. e. optimum filling and torque are achieved. 20 Thus, while all inlet valves are fully operative at a high rpm in the full load range, only one inlet valve is operative in the underload range, which permits the charge movement in the combustion space. 25 The embodiment shown in Figure 6 differs from that shown in Figure 1 in that another valve 87 is arranged between the two intake tubes 25 and 27, providing additional support for the resonance characteristic. In the lower rpm range, both valves 19 and 87 are closed. In the middle rpm 30 range, valve 19 remains closed and valve 87 is opened. In the upper rpm range,both valves 19 and 87 are opened. The position of the movable partition 17, like that of valves 19 and 87, is controlled by controller 61. Figure 7 shows another use of variable intake tubes 13 on the example of a four 35 cylinder series motor. To better adapt the vibration characteristic or the resonance characteristic of the intake system to the operating parameters of the combustion engine, individual volumes V2 and V3 are connected to the volume of resonance WO 97/08434 PCT/EP 96/03586 7 chamber 15 by means of valves 88 and 89 in the manner of a Hemholtzresonator Valves 88 and 89 are controlled by control unit 61. At a low rpm, valves 88 and 89 remain open, and with an increase in rpm, valve 89 is closed and then 88 is closed. 5 It is self-evident that numerous modifications of the embodiment of the invention described here are possible: For examble, the displacement of slide valve 37 may be controlled by an electric motor, a hydraulic mechanism or by other drive mechanisms. 10 The cross section of the intake channel can also be varied by a movable wall in it which is inherently flexible and is filled with a fluid as a function of operating point, for example, where parts that are mounted on it and are provided with a closing face increasingly close the inlet channels or outlet openings of the 15 resonance chamber.

Claims

1. An intake system for an internal combustion engine with at least one cylinder (4) with multiple inlet channels (10, 11), with an inlet valve working in each of them, and an intake tube with an intake channel (13) connected to the inlet channels, 5 characterized in that the device for altering the effective cross-section of the intake channel (13), for the purpose of controlling the charging motion in the cylinder at partial load, in accordance with performance characteristics and for the purpose of balancing oscillation processes according to modulation of the amplitude of the low-pressure wave in the intake channel (13) lat full load, 10 features a moving wall (17) which extends along the intake channel (13) and determines the latter's effective cross-section, whereby this moving wall (17) can be moved from a position in which the cross-section of the flow channel is reduced and only one inlet channel (10) is released, forming a flow path with a reduced cross section, into a position in which all the inlet channels (10, 11) are 15 released, forming a flow path with a maximum cross section.

2. An intake system according to claim 1, characterized in that the slide valve (37) is designed with a closing face to inlet channels (10, 11) and/or to the resonance chamber (15). 20

3. An intake system according to claim 2, characterized in that the intake channel (13) has a rigid part (31) which has a U shaped cross section on the whole and whose legs (33, 35) accommodate a slide 25 valve (37) which contains the partition (17) which is guided on the inside walls of the leg and closes the open side of the U shape, with the displacement of said slide valve varying the cross section of the intake channel. WO 97/ 08434 PCT/EP 96/03586 9

4. An intake system according to claim 2 or 3, characterized in that the rigid part (31) with a U-shaped cross section is accommmodated in a housing (47), and the slide valve (37) has flanges (39, 41) which project outside the U shape and together with the housing form piston 5 cylinder units (49, 51) for moving the slide valve.

5. An intake system according to claim 4, characterized in that the slide valve (37) has a U-shaped cross section, and a half dog (57) in the housing (47) which projects into the U-shaped cross section of 10 the slide valve.

6. An intake system according to one of claims 1 through 5, characterized in that a pneumatic drive unit (59, 63, 55) which is controlled by an electronic controller (61) is provided to move the partition (17). :15

7. An intake system according to one of claims 1 through 6, characterized in that the combustion engine has multiple cylinders, and the intake channels (13) with a variable cross section leading to the individual cylindres 20 lead out from a resonance chamber (15) whose volume can be subdivided into two chambers (21, 23) by means of a valve (19), where the valve (19) is open at a high rpm in the full load range. 25

8. An intake system according to claim 7, characterized in that a connecting channel that can be closed by means of another valve (87) is arranged between two intake tubes (25, 27), each of which connects one of the chamber (21, 23) to a throttle valve part (29) to control the power of the combustion engine, where the additional valve (87) is open in the middle and 30 upper rpm ranges.

9. An intake system according to one of claims 1 through 6, characterized in that the intake channels (13) which have a variable cross section 35 lead out from a resonance chamber (15) with a volume Vi to which is connected another chamber with a volume V2 , where a valve (88) is open between volumes VI and V2 at a low rpm and closes with an increase in rpm.