DE10361913A1 - "Turbo lag" (charging support with storage) - Google Patents

Abstract

Internal combustion engines with turbochargers for charging show a more or less pronounced torque weakness in the lower speed range. With the present invention, this torque weakness is compensated. DOLLAR A The torque weakness, due to insufficient charging of the engines in the lower speed range, is compensated by charging with air from a storage tank. DOLLAR A All vehicles equipped with exhaust gas turbochargers, d. H. Passenger cars, trucks, buses, tractors and military vehicles, with the device according to the present patent new or, in sufficient space, can be retrofitted and use the invention. If necessary, this also applies to all other mobile or stationary, such equipped facilities, eg. As in ships, locomotives, small aircraft, combined heat and power plants etc.

Description

nowadays will be a variety of cars and commercial vehicles with turbocharged Engines equipped.

Especially Diesel engines in truck and passenger car construction, but also partially gasoline engines become prevalent with exhaust gas turbochargers (AGT) for charging, i. for pre-compaction the intake air equipped.

Of the The author goes by the well-known in the automotive industry technology of charging with exhaust gas turbochargers. ( "Expertise for automotive technology ", publisher Europa-Lehrmittel. Nourney, Vollmer GmbH & Co. Europa Nr.20108, Section 2.5, p.371ff.)

The Working principle of this AGT is based on the utilization of the inner Energy of the exhaust gas of an engine for pre-compression of the intake air This engine, the so-called charging, a combination of exhaust gas turbine and intake air fan.

In first approximation behave the performance of the AGT approached proportional to the third power of the exhaust gas volume flow. This Behavior causes, in particular in the lower range of the speed band an engine with AGT, where only a small exhaust gas flow to disposal stands, the performance of the AGT and thus the pre-compression of the intake air even very small fails.

there the exhaust gas volume flow (AGV) and the intake air flow are due (ALS) mutually positive: a large AGV causes over the AGT, with a certain time delay, an increase in the ALS, which, after passing through the 4-clock or 2-stroke process in the engine, in turn to an even higher AGV leads etc.

This again explained the generally steep increase in the pre-compaction effect, ie the charge, and thus the torque increase, with increasing Motor speed, up to the maximum torque Mmax at the speed n (Mmax).

To the Protection of the motor against overload Therefore, there is a charge pressure limitation (LDB), which is the effect the charge is limited from the energy of the exhaust gas, which in the following, with increasing speed above n (Mmax), then to a sinking Torque contributes (Image 1).

Just this for Engines with AGT typical torque characteristics has a design-related fundamental weakness on: the relatively low torque at the beginning of the rev range, called turbo lag.

A Definition of the size of a Turbo hole does not exist, so should the speed range of the turbo lag here with the lower limit> idle speed (no) <and the upper one Limit> speed of the the first time the nominal torque (n (Mn)) <is reached.

Furthermore is defined an extended turbo lag, in the boundaries between n (Mn) to n (Mmax). this leads to in addition to a higher valuation the effect of the present invention.

Disadvantages of the turbo lag

• - just low pulling power of the engine in the lower speed range,
• - therefore necessary downshift for speeding up or overcoming of driving resistances,
• - connected with operation of the engine in the higher speed range,
• - What to more wear the moving parts,
• - one higher Consumption causes and
• - louder engine noise causes.
• - In order to Driving comfort also drops.

It is already possible today to reduce the turbo lag by expensive design measures but not completely or almost completely off. As a rule, these are constructive measures on the turbocharger itself, e.g. variable Intake geometry, tandem loader etc.

reason for the Turbo hole is primary the missing or insufficient precompression (charging) the intake air in the lower speed range.

the is in the present invention with compressed air from a Buffer memory encountered.

In trucks, which generally have compressed air reservoirs for operating the brake system, compressed air is drawn in a necessary quantity and with the working pressure permitted for the engine, guaranteed by a reducing valve (RV), and during operation in the speed range with insufficient torque Intake air to the turbocharger via a control valve (SV) supplied. SV is controlled by a controller (Rg), which receives pulses from the accelerator pedal (Gp) and the tachometer (Dm). A check valve (R) verhin prevents backflow of the compressed air to the AGT as long as its pressure is higher than the boost pressure of the AGT, and immediately assures the filling of the cylinders with this compressed air until after-flow of the sufficiently charged air from the AGT.

Provided the engine over a charge air cooler (LLK) has (Optionally indicated in Figure 2) is to weigh whether the compressed air from the DLS, which by a Teilentspannung- from the accumulator pressure in the DLS to the maximum permissible Boost pressure - subcooled is, is fed directly into the cylinder or even before the intercooler. Its effect would be with the latter method, however, could be reduced cold intake air negatively affects the combustion process in the cylinder. In any case, the real intake air temperature in the engine management are processed. As a basic solution is from a feeder after intercooler gone out (Photo 2).

The Maintaining a minimum air pressure in the compressed air reservoir For the safe operation of the brake system has priority over the support of the Motor charging and must be ensured by a corresponding regulation become.

Provided is still no compressed air storage in the car is available, is a separate Compressed air storage (DLS) installed. This one is running of the engine through the turbocharger with the maximum allowable boost pressure charged. For this purpose, the inflow valve V1 becomes a check valve executed an independent one Backflow of the stored air in the intake pipe (AR) to prevent.

In order to This DLS remains loaded until the support of the Charging is retrieved. Again, a check valve R is provided (Fig 3).

requirement for the Function of this support Charging is a minimum operating time of the engine in the range the maximum charge pressure before the possible use of the DLS. therefore the described method does not work immediately immediately after the start without o.g. Operating range has been reached is. This disadvantage is acceptable in practice, however, because the Requirement for compensation of the turbo lag i. a. R. only when driving in higher Grades, so after passing through the lower gears in accelerating the Cars, necessary. The engine was i. a. R. already temporarily operated within the range of the maximum boost pressure of the AGT, where the DLS was charged.

First opens on request the outflow valve V 2 and the compressed air flows into the AR. The request arises from the depression the accelerator pedal in the low torque range, ie in the region of the turbo lag, above the idle speed n (o), before reaching a sufficiently high torque for acceleration of the vehicle. A regulator, acted upon by the signals of the gas pedal (Gp) and the tachometer (Dm) controls V 2, as in the presence of a DLS in truck with pneumatic brake (see above).

The Dimensioning of the separate compressed air reservoir depends on various parameters, such as engine displacement, design and responsiveness of the turbocharger, Boost pressure, torque curve of the engine, etc. and therefore its design not the subject of this invention.

To Note that charging with compressed air in the said Speed range causes that with little delay even the AGV and thus the turbocharger on its own already one growing boost pressure supplies and thus, so to speak, the memory supersede and thus on the support the charge from the store with increasing speed increasingly can be waived.

This Effect leads constructive to a minimization of the storage volume.

In the speed range in which the effect of the turbocharger for Charging the intake air and thus not to increase the torque sufficient, supported compressed air from a DLS the charging process (s.3.).

In order to develops the engine in this speed range, between n (o) and n (M (n)) is a much higher one Torque, near the maximum torque M (max), as well as beyond up to the speed n (Mmax), opposite the torque curve without memory support- (Figure 4).

This makes it even more possible to use the engine in this speed range to accelerate or to overcome other driving resistance, without having to change to lower gears. The otherwise associated fuel consumption is eliminated, the engine runs quieter and ride comfort is increased. In addition, the speed-related wear of the moving parts on the engine decreases and the engine oil consumption or its aging process is slowed down. The climate-relevant and health-endangering emissions of the engine also decrease due to the more frequent operation with lower speeds in high gears. In addition, the clutch is spared when starting, it wears less. Especially in cars with hand-operated Ge the active driving safety increases through this power reserve for acceleration, without a manual shift, which would require time and attention from the driver.

It is possible, too, that the constructive effort for the AGT which serves to reduce the turbo lag to decrease in size (e.g., by variable suction geometry or the like). This Effort can be optimized with the effort to create the DLS, because this is growing necessarily with the size of the Compensating turbo lag, the turbo lag, however, grows with the reduction the design effort at the AGT.

In Automotive with automatic transmission reduces the operating life of the torque converter clearly, it is over a significantly expanded speed range a rigid coupling possible, what the operation of the hydraulic torque converter and thus the Fuel consumption, even more than the manual transmission, reduced and driving comfort also increased. This in turn reduces also the wear in the Automatic transmission, and also the aging of the transmission oil.

For the business ancillary equipment of the motor vehicle powered by the engine (e.g. Generator, air conditioning, etc.) are in the range between n (o) and n (Mmax) more power reserves available. Their driving force requirement affects less noticeable on the acceleration reserves of the vehicle in this speed range out.

It is about it also possible the separate DLS by an additional compressor operated by the internal combustion engine or an electric motor, with compressed air to load, as happens in trucks with compressed air brake system. However, this increases the equipment and the operating costs compared to the Charging the DLS by the AGT.

Only the DLS can, because of the higher operating pressure the compressor, smaller. Advantage of this technical solution would be an immediate functionality after the engine starts, without the AGT before already the maximum Must have delivered boost pressure.

In the speed range in which the effect of the turbocharger for Charging the intake air and thus not to increase the torque sufficient, supported compressed air from a DLS the charging process (s.3.).

In order to develops the engine in this speed range, between n (o) and n (M (n)) is a much higher one Torque, near the maximum torque M (max), as well as beyond up to the speed n (Mmax), opposite the torque curve without memory support- (Figure 4).

In order to it is more common possible, the engine also in this speed range for acceleration or to overcome other driving resistance to use without going into lower gears to have to change. The otherwise associated fuel consumption is eliminated, the The engine is running quieter and the ride comfort is increased. In addition, the speed-related decreases Wear the moving parts on the engine and the engine oil consumption or its aging process is slowed down. Also the climate-relevant and health-endangering ones Emissions from the engine decrease due to more frequent operation at lower speeds in high corridors. In addition, the clutch is spared when starting, it wears less. In particular, in vehicles with manual transmission increases the active driving safety through this power reserve for acceleration operations, without one manual shift, what time and attention from the driver would demand.

It is possible, too, that the constructive effort for the AGT which serves to reduce the turbo lag to decrease in size (e.g., by variable suction geometry or the like). This Effort can be optimized with the effort to create the DLS, because this is growing necessarily with the size of the Compensating turbo lag, the turbo lag, however, grows with the reduction the design effort at the AGT.

In Automotive with automatic transmission reduces the operating life of the torque converter clearly, it is over a significantly expanded speed range a rigid coupling possible, what the operation of the hydraulic torque converter and thus the Fuel consumption, even more than the manual transmission, reduced and driving comfort also increased. This in turn reduces also the wear in the Automatic transmission, and also the aging of the transmission oil.

For the business ancillary equipment of the motor vehicle powered by the engine (e.g. Generator, air conditioning, etc.) are in the range between n (o) and n (Mmax) more power reserves available. Their driving force requirement affects less noticeable on the acceleration reserves of the vehicle in this speed range out.

Claims (3)

Installation of a compressed air reservoir (DLS) in a vehicle for charging (pre-compression) the intake air for the KF7 driving internal combustion engine with exhaust gas turbocharger (AGT), in a speed range in which the torque of the engine, due to the characteristics of his AGT, clearly below the maximum torque, and in the speed range before reaching the maximum torque, is (in turbo lag). This compressed air reservoir is charged either by the AGT or by a separate compressor. Controlled supply of the stored compressed air to the intake air, before or after a possibly existing intercooler in the flow direction of the intake air. Use of an existing compressed air storage for same purpose as described under 1. in motor vehicles, which with a Compressed air storage for other purposes, e.g. to operate the brake system, already equipped are. Equipment of the system, consisting of compressed air storage, Engine and exhaust gas turbocharger, with the part 3 "Description of the technical Solution ... " and control features, such as check valve R, control valves SV, Control valve RV, valves V 1 and V 2 and regulator Rg and the control technology Compounds of Rg to Gp, Dm and SV or V 2 ..