Internal combustion engine

Abstract

In an internal combustion engine with exhaust gas turbochargers which operate in parallel and of which at least one can be switched on and off by a charge air duct blocking arrangement including a charge air duct blocking element, the charge air duct blocking arrangement is adapted to provide for a certain movement characteristic of the charge air duct blocking element resulting in a slower movement of the charge air duct blocking element resulting in a longer duration for the air duct blocking element to reach its open position and a faster movement during closing resulting in a rapid closing of the charge air duct blocking element.

Claims

1. An internal combustion engine (5) including exhaust gas turbochargers (1, 3) which operate in parallel and one of which can be switched on and off by exhaust gas duct blocking arrangement (21) and a charge air blocking arrangement (43) including a charge air duct blocking element (45), the charge air duct blocking arrangement (43) being adapted to follow a predefined movement characteristic of the charge air duct blocking element (45) which provides for a longer duration for the opening of the air duct blocking element (45) than for the closing thereof.

2. The internal combustion engine (5) according to claim 1, wherein the charge air duct blocking arrangement (43) is adapted to perform either one of actively slowing down the opening of the charge air duct blocking element (45) and not slowing the charge air duct blocking element (45) during the closing thereof.

3. The internal combustion engine (5) according to claim 1, wherein the charge air duct blocking arrangement (43) is designed to provide, within the frame of the predefined movement characteristic, an engine operating state-dependent opening characteristic of the charge air duct blocking element (45).

4. The internal combustion engine (5) according to claim 1, wherein the charge air duct blocking arrangement (43) is adapted to adjust, within the frame work of the predefined movement characteristic, an opening characteristic with a relatively shorter or a relatively larger opening movement deviation of the charge air duct blocking element (45) and/or the charge air duct blocking arrangement is further adapted to control the charge air duct blocking element (45) so as to assume, within the predefined movement characteristic, at least one predetermined partial opening interim rest position during the opening of the charge air duct blocking element (45).

5. The internal combustion engine (5) according to claim 1, wherein the charge air duct blocking arrangement (43) is provided with a hydraulic control arrangement for the charge air duct blocking element (45) and includes a hydraulic fluid flow throttling device (61) with a smaller hydraulic fluid flow cross section for the adjustment of a slow movement profile for opening the valve and a larger hydraulic fluid flow cross-section for the a fast movement profile for closing the charge air duct blocking element (45).

6. The internal combustion engine (5) according to claim 5, wherein the charge air duct blocking arrangement (43) includes the smaller hydraulic fluid flow cross-section in a hydraulic fluid flow connection (59) to a control cylinder (47) of the charge air blocking element (45) in the form of a throttling device (61) and the larger hydraulic flow cross-section in the form of a by-pass line (63) which by-passes the throttling device (61) and is provided with a check valve (65) permitting rapid closing of the charge air duct blocking arrangement (43).

7. The internal combustion engine (5) according to claim 6, wherein the charge air duct blocking arrangement (43) is adapted to conduct the hydraulic control fluid selectively via the smaller hydraulic fluid flow cross-section for the movement of the charge air blocking element (45) relatively slowly to an open position or via the larger hydraulic fluid flow cross-section for the adjustment of the movement profile providing for a rapid closing of the charge air blocking element (45).

8. The internal combustion engine (5) according to claim 1, wherein the charge air duct blocking arrangement (43) includes a valve (67) via which a hydraulic fluid flow from, or to, a control cylinder 47) for activating the charge air duct blocking element (45) can be controlled to be throttled for a slow opening of the charge air duct blocking element (45) and unthrottled for a fast closing of the charge air duct blocking element (45).

9. The internal combustion engine (5) according to claim 1, wherein the charge air duct blocking arrangement (43) includes an electrically operated controller (69) which is operatively connected to the charge air duct blocking element (45) for the opening and closing thereof and also connected to a control unit of the internal combustion air engine (5).

10. The internal combustion engine (5) according to claim 9, wherein the controller (69) is adapted to provide different opening speeds and positions of the charge air duct blocking element (45) during an opening procedure for an engine operating point dependent opening characteristic.

11. The internal combustion engine (5) according to claim 1, wherein the charge air duct blocking arrangement (43) includes a hydraulic control cylinder (47) which is operatively connected to the charge air duct blocking element (45) for the activation thereof, and the control cylinder (47) is provided with a proportional valve (73) and a travel distance measuring arrangement (75) which, in an operative association with the control cylinder (47), provides for a defined opening control of the charge air duct blocking element (45) with different opening speeds and positions, in particular an engine operating state-dependent opening characteristic, so as to avoid turbocharger pumping.

12. The internal combustion engine (5) according to claim 1, wherein the opening duration of the charge air duct blocking element (45) relative to the closing duration thereof is adjustable in the range of 5:1 to 20:1.

13. The internal combustion engine (5) according to claim 12, wherein the charge air duct blocking arrangement (43) is adapted to provide for a charge air duct blocking element opening characteristic with which the charge air duct blocking element (45) opens continuously moving steplessly or discontinuously over the whole opening travel distance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows schematically, in an exemplary representation, exhaust gas turbochargers of an internal combustion engine and an activating arrangement for one of the exhaust gas turbochargers in a particular embodiment of the invention.

(2) FIG. 2 shows, in an exemplary view similar to FIG. 1, another preferred embodiment of the invention.

(3) FIG. 3 shows, in an exemplary view similar to FIGS. 1 and 2 an additional preferred embodiment of the invention, and

(4) FIG. 4 shows in an exemplary view similar to FIGS. 1, 2 and 3, a further preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(5) In the following description and in the drawings identical elements with the same or similar functions are designated by the same reference numerals.

(6) FIG. 1 shows, in an exemplary view, two exhaust gas turbochargers 1, 3 arranged in parallel of an internal combustion engine 5, that is a base charger 1 and an activatable or deactivatable exhaust gas turbocharger 3 as well as an activation and deactivation arrangement 7 by which the activatable turbocharger 3 can be activated or deactivated.

(7) A respective exhaust gas turbocharger 1, 3 comprises, in a well known manner, a compressor part (compressor wheel) 9 and a turbine part (turbine wheel) 11. The compressor part 9 is arranged in a charge air duct 13 of the internal combustion engine (shown in the Figures in an exemplary manner only for the activatable turbocharger 3) whereas the turbine part 11 is arranged in an exhaust gas duct 15.

(8) The bearings of the turbochargers 1, 3, that is their shafts 17, are included in an engine oil circuit or hydraulic circuit 19 of the internal combustion engine 5 which oilor hydraulic fluid circuit 19provides for the motor oil or respectively the hydraulic fluid for the activation arrangement by which the exhaust gas turbocharger 3 can be hydraulically activated and deactivated. The hydraulic circuit 19 is supplied with pressured hydraulic fluid by an engine-driven oil pump of the internal combustion engine 5.

(9) The activation arrangement 7 includes for the activation and the deactivation of the exhaust gas turbocharger 3 an exhaust gas duct blocking arrangement 21 with an exhaust gas duct blocking element 23 which is in the form of a control flap pivotally arranged in the exhaust gas duct 15. For the control of the exhaust gas duct blocking element 23 the exhaust gas duct blocking arrangement 21 includes a hydraulically operated control cylinder 25 in operative connection with the exhaust gas duct blocking element 23 whose two cylinder chambers 29, 31, which are separated by a piston 27, can be alternatively pressurized or, respectively, depressurized via a 4/2 way valve or a control valve 33 arranged in the hydraulic circuit 19 (and the respective duct sections 35, 37) depending on the valve setting.

(10) In a position of the control valve 33 as shown in FIG. 1, the piston 27 of the control cylinder 25 is moved to the left by the in-flow of pressurized hydraulic control fluid admitted to the right-side cylinder chamber 29 and the release of the control fluid from the left side cylinder chamber 31 so that the exhaust gas duct blocking element 23 is moved by the elbow lever 39 which is connected to the piston 27 to its open position. When, on the other hand, the valve 33 is moved to its other position (not shown) the piston 27 is moved to the right as now the left cylinder chamber 31 is pressurized while the hydraulic fluid is released from the right cylinder chamber 29. As a result, the exhaust gas duct blocking element 23 is moved by the piston 27 via the elbow lever 39 to its closed position so that the supply of exhaust gas to the turbine of the exhaust gas turbocharger 3 is interrupted that is the exhaust gas turbocharger 3 is shut down. The hydraulic fluid released from the control cylinder 25 may be collected in a reservoir such as a tank 41.

(11) As further shown in FIG. 1, the activation arrangement 7 comprises also a charge air duct blocking arrangement 43 with a charge air duct blocking element 45. The charge air duct blocking arrangement 43 also includes a hydraulic control cylinder 47 which also includes two cylinder chambers 49, 51 which are separated by a piston 53 that is movably disposed in the cylinder 47. In contrast to the control cylinder 25 of the exhaust gas duct blocking arrangement 21, hydraulic control fluid can be admitted only to one of the cylinder chambers, that is the chamber 49.

(12) The piston 53 is operatively connected to the charge air duct blocking element 45 which, as shown in the Figure, is an air flap which is supported so as to be pivotable between an open and a closed position (shown in a dotted line). The elbow lever 55 or, respectively, the piston rod part thereof is further engaged by a tension spring 57 ensuring a reliable opening of the charge air duct blocking element 45.

(13) The charge air blocking element or flap 45 arranged in the charge air duct 13 upstream of the compressor 9 of the exhaust gas turbocharger 3 controls the intake air flow (arrow A) from an air filter (not shown) to the air compressor 9 and is subjected to a pressure differential when the compressor wheel of the further exhaust gas turbocharger, that is the turbocharger 3, is activated, which pressure differential causes the flap 45 to open. To permit the opening of the flap 45, the hydraulic pressure fluid (oil) in the chamber 49 of the control cylinder 47 needs to be released from the cylinder chamber 49. This is possible with the control valve 33 arranged in the position as shown in FIG. 1 in which position the hydraulic fluid can flow out of the cylinder chamber 49 and, via the drain line 59 to the tank 41. During the release of the pressurized fluid from the chamber 49, the piston 53 moves under the tension force of the spring 57 together with the elbow lever 35, to the left thereby opening the charger air flow control flap 45.

(14) The speed of movement of the control flap 45 is controlled by the movement of the piston 53 in the control cylinder 47 that is the release of the hydraulic fluid from the chamber 49 via the hydraulic fluid flow connection 59 to the tank 41. For closing the charge air duct blocking flap 45, hydraulic pressure fluid is again admitted by a switchover of the control valve 33 so that hydraulic pressure fluid is supplied from the valve 33 via the duct section 35 and the hydraulic fluid flow connection 59 to the chamber 49 of the cylinder 47, whereby the piston 53 is moved by the elbow lever 55 to the right and the flap 45 is closed.

(15) This in accordance with the invention provides for a charge air duct blocking arrangement 43 closing with a predetermined movement characteristic of the charge air duct blocking element 45 which is adjustable and which has a relatively slow opening speed and a comparably fast closing speed. With this set-up, a charger pumping can be effectively avoided since the air flow through the exhaust gas turbocharger 3 increases relatively slowly, that is not suddenly, so that the base charger 1 can maintain its air flow rate.

(16) For the adjustment, that is the establishment of the predetermined movement characteristic, the hydraulic fluid flow connection 59 to the control cylinder 47 of the charge air duct 43 includes a throttling device 61 with a by-pass 63 as shown in FIG. 1. The by-pass 63 includes further a check valve 65. This arrangement provides for a relatively small flow cross-section in the fluid flow connection 53 for the control fluid released from the control cylinder 47 of the charge air duct blocking arrangement 43 during opening of the air flap 45 as the by-pass 63 is blocked by the check valve 65 so that the control fluid must pass through the throttling device 61. In this way, the desired relatively slow opening of the intake air flap 45 is achieved as the drainage of the hydraulic control fluid is inhibited that is slowed resulting in a slow displacement of the piston 55, the elbow lever 55 and the opening of the air flap 45.

(17) With the closing of the intake air flap 45 upon switching over the control valve 33 for directing hydraulic control fluid to the control cylinder 47, the check valve 65 in the by-pass 63 is opened providing for a large flow cross-section by-passing the throttle 61 and an undelayed movement of the piston 53 in the control cylinder 47 to the right resulting in a rapid closing of the intake air flap 45.

(18) In an advantageous further development of this arrangement which can be realized in a simple and inexpensive way, the throttle 61 may have an adjustable cross-section whereby the opening characteristic of the intake air flap can be adjusted for an adjustment of the flap opening speed that is the duration of the flap opening process. In the arrangement of FIG. 1 furthermore, a safety valve may be provided which safety valve protects the further exhaust gas turbocharger 3 from over-speeding. Such a safety valve could be arranged for example in the hydraulic fluid flow connection so as to be opened for discharging fluid depending on the pressure ahead of the charger 3 (the admissible low pressure corresponds in particular to the charger speed limit minus a safety margin).

(19) FIG. 2 shows another embodiment of the internal combustion engine 5 according to the invention, that is, more specifically, it is focused on the activation arrangement 7 and the exhaust gas turbocharger 1 or, respectively 3, wherein, different from the above-described embodiment in the charge air duct blocking arrangement 43, the hydraulic fluid is selectively conducted through a smaller or a greater hydraulic fluid flow cross-section for a relatively fast opening or, respectively, a relatively slow opening of the charge air duct blocking element 45.

(20) Herein, the charge air duct blocking arrangement 43 includes a valve 67, in particular a 3/2 way valve, by which a fluid flow connection 59 of the control valve 33 with the control cylinder 47 is switched via a first line section 59a including a small flow cross-section or the flow connection 58 may be established via a second line section 59b with a larger flow cross-section. To provide for the smaller flow cross section in the first line section 59a, the first line section 59a includes the throttling element 61, whereas the second line section 59b includes no throttling means that is it has a relatively large flow cross-section for a fast closing of the blocking element 45.

(21) In the position of the valves 33, 67 as shown in FIG. 2 pressurized control fluid is released from the control cylinder 47 via the first line section 59a, that is its flow is throttled by the throttle 61 so that the charge air duct blocking element 45 is opened slowly. If, on the other hand, depending on the operating state of the engine, the charge air blocking element 45 is to be opened rapidly, the valve 67 can be moved to a position (not shown) in which the control fluid can be drained from the control cylinder 47 unthrottled via the line section 59b. In this position of the valve 67, the charge air duct blocking element 45 can also be rapidly closed so that, for a fast closing of the charge air blocking element, only the control valve 33 needs to be switched. With this solution, a slow opening characteristic of the charge air blocking element 45 can be obtained when necessary to avoid charger pumping whereas, in all other operating states, the charge air blocking element 45 can be opened rapidly that is the further exhaust gas turbocharger can be activated rapidly. In this configuration, the charge air blocking arrangement 43 is suitable for use in combination with an engine operating state-based software control of the control valve 33 and also the valve 67.

(22) FIG. 3 shows an activation arrangement 7 for the further turbocharger 3 whereindifferent from the embodiments described abovethe charge air duct blocking arrangement 43 includes, in place of the hydraulic control, an electric control of the charge air duct blocking element 45 for obtaining the desired movement characteristic.

(23) To this end, the charge air duct blocking arrangement 43 is provided with an electric control motor or respectively, a controller 69 by which the charge air duct control flap 45 can be opened or closed at different speeds, in particular with different opening speeds. With such an arrangement the controller 69 may advantageously also provide for intermediate positions of the charge air blocking element 45, that is partially open positions or a multi-stage opening profile resulting in a still greater variability. Also in connection with this embodiment of the invention, the charge air duct blocking element 45 is adjusted preferably dependent on the operating state of the internal combustion engine that is by a suitable implementation of control programs of the control software of the charge air duct control arrangement 43 controlling the controller 69.

(24) FIG. 4 shows a further activation arrangement for the turbocharger 3 of the internal combustion engine 5, wherein the charge air duct blocking arrangement 43 is operated hydraulically but also provides for highly variable adjustment capability of the opening characteristic of the blocking arrangement 43. The charge air duct blocking arrangement according to FIG. 4 again comprises a hydraulic control cylinder 7 which is operatively connected to the charge air duct blocking element 45 for the control thereof. However, contrary to the hydraulic control arrangements of the air flow control flaps 45 of FIGS. 1 and 2, the charge air duct blocking arrangement 43 includes a hydraulic control circuit 71 which is separate from the control for the hydraulic control circuit for the exhaust gas, but which also uses hydraulic fluid or oil from the internal combustion engine oil circuit.

(25) The control cylinder 47, which in this embodiment, includes two hydraulically controllable chambers 49, 51 is provided with a proportional valve 73, in particular a 4/2 way proportional valve as well as a travel distance measuring arrangement 75, which in an operative connection with the control cylinder 47, facilitates a predetermined opening control of the charge air duct blocking element 45 with different opening speeds and positions. With such an arrangement, in particular in combination with a control of the proportional valve 73 by means of an engine control unit (ECU), the charge air duct blocking element 45 can be opened for the addition of the exhaust gas turbocharger 3 over a predetermined travel distance and with a predetermined opening speed. As control signal, for example a PWM (pulse-width-modulated) signal may be used. With such an arrangement advantageously also a multi-step opening of the charge air duct blocking element is made possible for example with, or in addition to, the movement characteristic with a relatively slow opening speed. In connection with a multi-step valve opening with predetermined blocking element positions, the air flow volume through the compressor 9 can be adjusted independently of the opening speed.

(26) Generally, it is the object of the present invention to provide with the charge air duct blocking arrangement 43 a blocking element movement characteristic with an opening movement duration for the charge air blocking element 46 which is 5 to 20 times as long as the time it takes to close the valve. It is also possible to provide with a charge air duct blocking arrangement 43 according to the invention a valve opening characteristic with which the charge air blocking element follows a pre-set movement over the duration of the opening or, respectively, the whole opening travel distance.

(27) The charge air duct blocking element 43 may also be arranged at the pressure site of the compressors 9 of the exhaust gas turbocharger 3.

LIST OF REFERENCE NUMERALS

(28) 1 exhaust gas turbocharger (base charger) 3 exhaust gas turbocharger (switchable charger) 5 internal combustion engine 7 activation arrangement 9 compressor part 11 turbine part 13 charge air duct 15 exhaust gas duct 17 shaft 19 hydraulic circuit 21 exhaust gas duct blocking arrangement 23 exhaust gas duct blocking element 25 control cylinder (of the exhaust gas duct blocking arrangement) 27 piston 29 cylinder chamber 31 cylinder chamber 33 control valve 35 duct section 37 duct section 39 elbow lever 41 reservoir, tank 43 charge air duct blocking arrangement 45 charge air duct blocking element 47 control cylinder (of the charge air duct blocking arrangement) 49 chamber 51 chamber 53 piston 55 elbow lever 57 tension spring 59 hydraulic fluid flow connection 59a first line section 59b second line section 61 throttling device 63 by-pass 65 check valve 67 valve 69 controller 71 hydraulic control circuit 73 proportional valve 75 travel distance measuring arrangement A intake air