DE3005108A1 - Exhaust gas driven turbocharger for IC engine - has motor operated exhaust gas by=pass valve with automatic controller - Google Patents

Abstract

Control is effected by a motor (46)-operated valve (38) in a bypass pipe (37) connecting the exhaust manifold (16) to the silencer (26) and outlet. Diverting exhaust gas away from the turbine (20) reduces the amount of air delivered by the compressor (22) of the charger to the inlet manifold (12). The motor is controlled by an automatic regulator responsive to sensors, e.g. inlet manifold pressure (52) and temp. (54) and engine speed (56). The proposed control eliminates the need for altering ignition timing of the engine to suit changed conditions of oepration.

Description

Ingolstadt, Jan. 18, 1980 IP 1635 DrBa / Dö

Internal combustion engine, in particular externally ignited four-stroke internal combustion engine with a compressor

The invention relates to an internal combustion engine, in particular externally ignited four-stroke internal combustion engine with a compressor according to the preamble of claim 1.

Supercharging, in particular exhaust gas turbocharging, is a more recent one Time often used means to increase the performance of internal combustion engines. When controlling the charge occurs thereby the problem that the maximum allowable pressure in the intake manifold is strong depends on the operating conditions of the internal combustion engine. For example, the maximum permissible boost pressure decreases as it increases Speed and with increasing temperature in the intake manifold. To avoid knocking as a result of excessive pressure in the intake manifold Combustion occurs, either the ignition point of the internal combustion engine (if this is externally ignited) is withdrawn and / or the boost pressure is lowered by opening a relief valve. The former measure generally leads to the deterioration of the Efficiency of the internal combustion engine and thereby an increase in consumption. The second measure requires precise control of the relief valve.

15 (50-54 / 0202 BAD ORIGINAL

-JS-

30051QB

Relief valves are known, which prevail in the intake manifold Pressure or, in the case of exhaust gas turbocharging, the pressure in the exhaust system and open as soon as a specified pressure value is exceeded in order to lower the pressure prevailing in the intake manifold either directly or by the fact that - with exhaust gas turbocharging - Part of the exhaust gas is diverted past the exhaust gas turbine. Such known controls work relatively sluggish and take into account the various parameters influencing the maximum permissible boost pressure in each case inadequately. this has As a result, the control of a blow-off valve, which, for example, only responds to the pressure prevailing in the intake manifold, must be designed so that the maximum permissible intake manifold pressure is not exceeded even at high ambient temperatures. at The internal combustion engine is then at lower ambient temperatures operated with intake manifold pressures which are below the maximum permissible values, which is disadvantageous for the effectiveness of the supercharging influenced.

The invention is based on the object of a generic internal combustion engine to be designed in such a way that operation is possible with an intake manifold pressure which is as close as possible to the highest in each case permissible intake manifold pressure.

This object is achieved with the features of main claim 1.

According to the invention, the relief valve is thus directly by means of an electric servomotor corresponding to a little-

30051Q8

at least one operating parameter of the internal combustion engine derived Signal controlled. The operating parameter is measured by means of a sensor, which works quickly and accurately, and is incorporated into a Converted control signal for the servomotor. It goes without saying that the control signal can pass through a comparator, so that it is only effective for opening the servomotor when it exceeds a threshold value that can be set on the comparator. As an operating parameter the internal combustion engine can, for example, the intake manifold pressure or the intake manifold temperature or the respective Ignition time of the internal combustion engine, provided that it is spark-ignited, or any other variable that exceeds the maximum permissible or influences the most advantageous intake manifold pressure in each case.

With the features of claim 2, an adaptation of the respectively prevailing intake manifold pressure to that in the intake manifold takes place in a simple manner The prevailing temperature, since at a higher intake manifold temperature the relief valve is already open at a lower intake manifold pressure will and vice versa.

With the features of claim 3 it is achieved that the intake manifold pressure decreases with increasing speed of the internal combustion engine, which, as explained in DE-OS 27 45 153, is advantageous.

"x

Claim 4 relates to an embodiment of the internal combustion engine directed, with which a particularly precise control of the servomotor and thus "the relief valve" takes place.

- 7 -

... 7 -

Finally, the features of claim 5 characterize a particular one simple embodiment of an internal combustion engine according to the invention.

The invention is applicable to all types of supercharging and internal combustion engines can also be used, for example, for mechanically charged diesel engines, as they lead to a quicker and more precise Control of the prevailing intake manifold pressure leads. The application of the invention is particularly advantageous for externally ignited vehicles Internal combustion engines with exhaust gas turbochargers.

It goes without saying that the invention can also be used extensively can be realized by electronics, for example in that a microprocessor provides the various for the optimal Intake manifold pressure-relevant operating parameters are fed and the microprocessor then the servomotor for the relief valve controls according to a program stored in the microprocessor.

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

They represent:

1 shows a schematic view of an internal combustion engine equipped with exhaust gas turbocharging and

Fig. 2 is a block diagram of the control of the actuating

13 0-084- / 0202

A blow-off valve 38 is connected to the exhaust manifold 16 via a connecting line 37, through which the exhaust gases the internal combustion engine 6, bypassing the exhaust gas turbine 20 directly can escape into the exhaust pipe 24. This blow-off valve 38 has a closure member 40 with a shaft 42, which, for example, interacts via a toothing with a pinion 44 of a servomotor 4 6. At the free end of the shaft 4 2 a slide 48 of a variable resistor 50 is attached.

A pressure sensor is used to measure the pressure prevailing in the intake manifold 12 52 and a temperature sensor 54 is provided for measuring the temperature prevailing in the intake manifold. To measure the speed of the Internal combustion engine 6, a tachometer 56 is provided.

According to FIG. 2, the pressure sensor 52, the temperature sensor 54 and the tachometer 56 are parallel to one another between voltage supply lines 60 and 62. The outputs of the pressure sensor 52 and the temperature sensor 54 are connected to the inputs of an adding stage 64, the output of which is an input of another Adder 66 is supplied, the other input of which is connected to the output of the tachometer 56. The adder 66 is connected downstream is a comparator 68 with an adjustable reference voltage source 70. The output of the comparator 68 gives a signal to an input of a switch 72 when the output signal · the Adding stage 66 is greater than the value of the reference voltage output by reference voltage source 70.

- 10 -

13 0 0 34/0202

- 3 -

motor for actuating the blow-off valve contained in the arrangement according to FIG. 1.

According to FIG. 1, an internal combustion engine 6 has a plurality of cylinders 8 in which pistons, not shown, operate. Every cylinder 8 is via a suction line 10 with a suction pipe 12 (drawn continuously) and via an outlet line 14 with an exhaust manifold 16 connected.

On the exhaust manifold 16 is an exhaust gas turbocharger designated as a whole by 18 connected, which has an exhaust gas turbine 20 and a turbocharger 22 on a common shaft. From the exhaust turbine 20, an exhaust pipe 24 leads to a muffler 26 of the exhaust of the internal combustion engine.

The outlet of the turbocharger 22 is connected to the suction pipe 12. In the inlet to the intake manifold 12 sits a cooperating with an accelerator pedal Throttle valve 30.

At the inlet of the turbocharger 22 is an air flow meter 34 arranged, which measures the throughput of the fresh air sucked in by the turbocharger 22 through an air filter 36. the Air throughput measuring device 34 works together with an injection system, by means of which in each suction line 10 one of the air throughputs corresponding amount of fuel is injected.

130034/0202 ORIGINAL BATHROOM

- ίο -

3Q0510B

The output of the adder 66 is also an input connected to a subtraction stage 74, the other input of which is connected to the reference voltage source 70 and the output of which is connected to another Input of switch 7 2 is connected. The output of the switch 72 is connected to an input 76 of a control circuit 78 connected, which controls the servomotor 46. The function of switch 72 is that it is the output of the subtracter 74 lets through as soon as there is a signal at the output of the comparator 68.

The slide 43 of the variable resistor 50 is via a line 80 is connected to a further input 82 of the control circuit 78. The structure and function of the control circuit 78 are, for example, as described in DE-OS 28 12 306 using a control circuit for a servomotor for adjusting a motor vehicle seat. It consists in the control circuit 78 responding to a difference between the signals present at the two inputs 76 and 82 the servomotor 46 rotates in a direction that the signal difference is reduced. In the example shown, assume that a signal zero at the input 76 and a voltage zero at the wiper 48 corresponds to a position of the servomotor 46 / in which the blow-off valve 38 is closed. If a voltage occurs at the input 76, the servomotor 46 actuates the closure member 40 of the blow-off valve 38 in the opening direction until the voltage on slide 48 corresponds to the voltage on input 76. Relieves the tension at input 76, the blow-off valve is increasingly closed; if it increases, it is increasingly opened.

- 11 -

130034/0202

- Ί I -

To explain the function of the arrangement described, it is initially assumed that the temperature prevailing in the intake manifold and the engine speed is constant, i. e. the output signals of the temperature sensor 54 and the tachometer 56 don't change.

The reference voltage source 7 0 is set to a value which is equal to the value of the output signal of the pressure sensor 52, which is the highest permissible for the temperature and speed Corresponds to the pressure in the intake manifold. If this pressure is now exceeded, an output signal appears at the output of the comparator 68, i.e. the switch 72 becomes permeable and leaves the difference between the pressure signal generated by the pressure sensor 52 and the reference voltage to the input 76 of the control circuit 78, whereby the blow-off valve 38 is opened until the voltage on the slide 48 is the same as the signal at input 76. As a result, the intake manifold pressure drops, which in turn reduces the voltage at input 76, which again the blow-off valve closes increasingly, etc. Overall, an intake manifold pressure is established which is precisely the highest permissible Corresponds to intake manifold pressure.

If, for example, the temperature in the intake manifold rises, the output signal of the temperature sensor 54 rises, which in turn causes the the signal supplied to the input 76 increases and the blow-off valve increasingly opens. The resulting intake manifold pressure thus drops with increasing temperature. In a very similar way, the

- 12 -

130034/0202

30051QB

end of intake manifold, pressure with increasing engine speed, which leads to an increase in the output signal of the tachometer 56.

It will be understood that numerous modifications to those described Circuit are possible. For example, threshold switches can be connected downstream of each sensor. The entire control of the Control circuit 78 can be implemented by means of a microprocessor. The arrangement can also be changed so that the Regulation in the closed position of the control valve not put out of operation is, but the servomotor 4 6 works on both sides of the closed position of the control valve and its closure member as soon as it has reached the closed position, increasingly pushes against the force of a spring in the closed position. The slide 48 of the variable resistor 5 0 is then to be connected directly to the shaft of the servomotor 46.

The blow-off valve 38 can also be designed in a conventional manner in that it is only opened by the exhaust gas pressure or the intake manifold pressure will. In addition, a relief valve can then be provided, which air compressed by the turbocharger 22 from the outlet of the Loader turbine 22 returns more or less to its entrance according to its opening.

130034/0202

Blank page

Claims (6)

Ingolstadt, January 18, 1980 II '1635 DrBa / Dö onukrai'tT.ascli i ne, especially freradeje ignite four-stroke internal combustion engine with a compressor Patent claims: 1 / internal combustion engine, especially four-stroke internal combustion engine with spark ignition with a compressor, which the fresh air supplied to an intake manifold of the internal combustion engine or "Compressed charge, and with one controlled as a function of at least one operating parameter of the internal combustion engine Relief valve to reduce the pressure effective in the intake manifold, characterized in that that to actuate the relief valve (blow-off valve 38) an electric servomotor (46) is provided, which of a control circuit (78) is actuated, which is derived from at least one operating parameter of the internal combustion engine Signal is supplied. 2. Internal combustion engine according to claim 1, characterized in that that the control circuit (78) the servomotor (46) according to the increase of an additive 130034/0202 , -BAD ORIGINAL : ■■■;,. Saucepipe pressure and suction pipe temperature composite signal controls so that the relief valve (blow-off valve 38) at Increase in this signal increasingly opens. 3. Internal combustion engine according to claim 1 or 2, characterized characterized in that a tachometer (56) is provided for measuring the speed of the internal combustion engine (6) is whose speed of the internal combustion engine is proportional Output signal of the control circuit (78) is fed and the relief valve (blow-off valve · 38) with increasing Speed · increasingly opens. 4. Internal combustion engine according to one of claims 1 to 3, characterized in that the control circuit a control circuit (48, 50, 80) which corresponds to the position of the relief valve (blow-off valve 38) Signal fed to an input (82) of the control circuit. 5. Internal combustion engine according to one of claims 1 to 4, characterized in that the control circuit (78) a threshold value control (68, 70, 72, 74) is connected upstream which is an opening of the relief valve (blow-off valve 38) prevented below predetermined operating parameters of the internal combustion engine. 6. Internal combustion engine according to one of claims 1 to 4, in which the compressor from the exhaust gas turbine of an exhaust gas turbocharger 1 3 0 0 ~ 3 2 / "0 2 0 2 is driven, which exhaust gas turbine is preceded by a blow-off valve is, at the opening of which exhaust gas is led past the exhaust gas turbine, characterized in that, that the relief valve]. is formed by the blow-off valve (38). 130034/0202 ORIGINAL BATHROOM