DE19633681A1 - Exhaust emission control for vintage motor vehicles - Google Patents

Abstract

The older type of vehicle is retro-fitted with a catalyser in the exhaust system. To ensure optimum fuel/air mixture under all conditions a fuel/air injector is fitted between the throttle valve and the engine. This supplements the fuel/air mixture supplied via the existing system using a feedback control from the exhaust sensor. The retrofit does not need replacement of the existing carburettor or fuel injection system. A processor control monitors the exhaust gas sensor, the engine speed and the fuel settings to provide optimum operating conditions for the engine.

Description

State of the art

• 1. Lambda controlled air bypass system from the company Paul Wurm, Am Wildbädle 4, 70329 Stuttgart.
• 2. Lambda controls from different manufacturers intervene in existing injection systems.
• 3. Installation of new complete engines in old driving witness (oldtimer) including the catalysts.

State of the art problems

For 1st reaction only in the "lean" direction by adding Air possible.

Re 2. The majority of end-of-life vehicles have carburettors as a mixture generator.

To 3. It only makes sense for high-quality "classic cars".

General problems

• - limited market value of end-of-life vehicles,
• - According to studies by TÜV and the like Organizations poorer maintenance of the old vehicles by their owners,
• - planned exhaust gas laws for 2- and 3-wheelers vehicles.

Conclusion

A retrofit kit must therefore

• - be inexpensive and low-maintenance
• - Emergency running properties have around the operating to ensure safety
• - be universally applicable.

These problems are addressed by the invention in Connection with a standard catalyst solved.  

4. Software

The control program is a spin in the controller number monitoring overrides warm-up, Transitional areas and the shutdown of the Controllers controls. This monitoring switches hysteresis controlled between warming up, transition areas and shutdown back and forth.

Warm up:
Switch-on limit is over 950 rev / min, corresponding to normal state lambda = 1.

Transition area:
Switching limit is less than 750 rev / min. Prevents engine shutdown in cold start, after pushing operation, etc. The PWM signal (pulse width modulation) switches to an average pulse width ratio; corresponds to a constant mixture enrichment.

Shutdown:
Switch-off limit is less than 500 rev./min. Control is switched off when starting, a sharp drop in engine speed and engine shutdown.

The above speed values are dependent from the internal combustion engine and adjustable. The ones listed here apply to VW Beetles with 1.6 ltr. Cubic capacity, 37 KW (50 HP).  

5. Function of the watchdog link

Signals from the controller become dependent from pulses from the controller to the valves passed on or blocked:

• A. Program runs perfectly and
• B. Speed pulses are received.
  Controller emits impulses for functionality and signals for the valves, watchdog element passes signals for valves
• A. or B. not available Consequence:
  The watchdog element switches off the voltage supply of both valves, ie the motor runs again uncontrolled in its original state. This prevents engine damage caused by a mixture that is too rich or too lean.

Explanation of the drawings

Fig. 1 drawing of the control valve on page 2.
Pos. 1 housing
Pos. 2 adjusting screw
Pos. 3 injection valve
Pos. 4 shut-off valve.

Fig. 2 arrangement of the mixture generator on an internal combustion engine on page 5.

Fig. 3 signal flow on page 5.

Fig. 4 microcomputer on page 6.
Pos. 1 controller
Pos. 2 watchdog
Pos. 3 shut-off valve
Pos. 4 injection valve.

Claims (6)

Advantage of the invention Lambda-controlled additional mixture generator of the regardless of the existing mixture generator (Carburetor, injection system) or the ge formed mixture by adding an additive mixture between throttle valve and burner room sets the total mixture to Lambda 1. The invention consists of a control valve in the filtered with an adjustable Airflow and injected fuel Additional mixture is formed and one electronic control loop. This controls in Dependence on lambda probe voltage, Engine speed and operating status the on spray nozzle and the shut-off valve for the Limp home. Universally applicable because regardless of the previous existing mixture generator. The environmental impact of producing a New vehicle or an internal combustion engine is higher than the burden of after armor brought to similar emissions End-of-life vehicle. Another important advantage of the invention is that it is not working properly Mixture through the regulated additive mixture can be compensated. (Aging, poorer maintenance of end-of-life vehicles). Great potential for retrofittable old vehicles testify.