DE9309617U1 - Stop-start automatic system for car engines with stop and go - and regulated city traffic - Google Patents

Description

-&Ogr;&Igr;&Ogr;. State of the art

The invention relates to the field of automotive electrics and electronics.

It deals with the problem of unnecessary pollutant emissions from idling car engines at traffic-controlled intersections or in traffic jams.

To solve this problem, a number of systems have been developed that automatically shut down the engine when certain sensor-detected positions of the gear lever, clutch, brake and accelerator pedals are in place, or that manually shut down the engine or restart it.

In the systems developed so far, at least one of the following points has had a negative impact on the performance characteristics of the shutdown devices:

0.1 The driving speed is not recorded by a signal. Theoretically, the engine can be switched off at high speeds. A sign near the engine stop device saying: "Only operate when the vehicle is stationary!" does not provide a reliable guarantee that this instruction will be complied with in the interests of operational safety.

0.2 The engine temperature is not recorded, which means that the stop-start device can also be activated when the engine is cold.

The first two points mentioned, if not taken into account by the driver, will cause malfunctions in the operational safety of the hydraulic system for brake booster and power steering and the catalytic converter.

0.3 To switch off the engine, the button must be pressed until the engine speed is 0. This takes about 1.2 s. This requires additional concentration from the driver.

0.4 The starting process is automatically interrupted after being triggered by pressing a button or pedal at a speed slightly above the speed generated by the starter (just over 200 rpm). The risk of "false starts" is therefore inevitable, since the decision "engine is running by itself" must be recognized by the system within a narrow limit.

Early detection of self-running is not necessary because there are differences of 600 rpm between the starting speed and the speed of the self-running engine at idle.

0.5 The starting process is not automatically interrupted after being triggered by pressing a button or pedal. This requires a high level of concentration from the driver, given the high level of noise from the traffic and the radio that may be switched on, in order to recognize that the engine is running and that he can complete the starting process.

0.6 The starting process is triggered by pressing the accelerator pedal. This is convenient, but not acceptable in modern vehicles, as the vehicle manufacturers repeatedly point out in their operating instructions that

indicate that the accelerator pedal must not be pressed under any circumstances during the starting process. The engine control units automatically ensure that the fuel-air mixture is enriched during the starting process.

If the accelerator pedal is also pressed, this will inevitably lead to an unacceptable over-enrichment of the mixture.

For modern vehicles, the accelerator pedal is completely unsuitable for initiating the starting process with retrofitted shutdown systems.

Startronic Type SK 12 / 06

1. Intended use, area of use

The Startronic SK 12/06 is a control unit that can be retrofitted into a car, including additional equipment, which, after integration into the existing vehicle electrical system, has the following effects:

1.1 The engine is switched off automatically or via the control unit at closed intersections or in traffic jams.

1.2 The engine is restarted via the control unit, whereby the start-up process is automatically interrupted if the engine runs on its own.

1.3 When driving with the lights on, the low beam is automatically switched off in the period from when the engine stops until the start-up process is completed in order to relieve the battery, so that only the parking light or tail light is on.

1.4 The engine can only be switched off (automatically or via the control unit) if

1.4.1 the engine operating temperature is reached,

1.4.2 the vehicle has come to a standstill.

1.5 An automatic engine shutdown after the vehicle has come to a standstill is guaranteed if a "critical" speed of 40 km/h has been exceeded beforehand. This critical speed can be continuously adjusted between approximately 20 and 60 km/h.

1.6 Exceeding this speed or activating the automatic engine shutdown is signaled optically by an LED so that the driver is made aware that the engine will switch off after the next vehicle stop.

1.7 If necessary, the activation of the automatic engine shutdown can be reversed via the control unit at a speed below the critical speed and above 0 km/h.

1.8 The engine can be switched off via the control unit after the vehicle has come to a standstill, if the critical speed has not been exceeded beforehand or the automatic switch-off is not active.

1.9 Results:

1.9.1 By avoiding as much as possible the useless idling of the engine, between 3 and 5 liters of fuel can be saved per tank of fuel in city traffic and when driving in traffic jams.

1.9.2 Fuel savings in relation to mileage reduce pollutant emissions, particularly carbon dioxide, which cannot be captured by even the best catalytic converter.

-2-Area of use

The Startronic SK 12/06 can be retrofitted in principle for cars with petrol engines, both with carburettor and with injector systems with or without catalytic converters from all manufacturers.

The Startronic system in this version is not suitable for cars with automatic transmission.

2. Structure and mode of operation

2.1 Structure

The Startronic system consists of the control unit (central unit) and the peripheral elements. The system also includes the interfaces to the vehicle's electrical system and the communication with the electrical system.

2.1.1 Central unit

The central unit is a circuit board (72 x 126 mm) equipped with electronic components, which is located in a Euro box housing (150 x 80 x 50 mm). The circuit board is provided with flat plug connections for communication with the on-board network and the peripheral elements. The box housing is either screwed to the sheet metal parts of the chassis under the hood in a thermally favorable place or can be installed under the dashboard in the passenger compartment.

The central unit controls all processes that ensure the effects described in point 1.

2.1.2 Peripheral elements

These include the controls:

2.1.2.1 Toggle switch for power supply of the central unit,

2.1.2.2 Miniature push button (operating unit) with the three different functions described in point 1,

and the display element:

2.1.2.3 a light-emitting diode which signals the activation of the automatic shutdown.

2.1.2.4 Additional equipment:

Speed sensor that must be inserted into the mechanical speedometer cable if there is no on-board speed sensor.

2.1.3 Interfaces to the vehicle electrical system

2.1.3.1 Voltage path when ignition is "On"

2.1.3.2 Voltage path "Starting"

2.1.3.3 Control line power transistor ignition

2.1.3.4 Voltage path low beam

2.1.3.5 Pulse path speed sensor

-3-

The on-board network is "tapped" or separated at these points and connected to the control elements and the central unit via additional cables.

2.2 Mode of action

To achieve the effects described in point 1, the Startronic system must be integrated into the interfaces of the on-board electrical system described in point 2.1.3.

When the ignition is "on" of the vehicle electrical system, the toggle switch that supplies power to the Startronic device is also supplied with on-board voltage. When the ignition is "off", the Startronic device is always de-energized, regardless of its toggle switch position. The voltage supply path is protected against short circuits by an additional fuse inserted into the cable.

The supply voltage is fed to the Startronic device via the flat plug connections 1 and 2. The central unit is protected internally by a 0.8 A fine-wire fuse.

The speed signals of the VDO cruise control speed sensor, which can be additionally inserted into the speedometer cable if required, are fed to the Startronic device via flat plug connection 3.
This requirement applies if the car

- has brake booster or power steering or both,

- but on the other hand is not equipped with an electronic pulse tachometer system. The signals from the on-board vehicle speed sensor are connected to connection 4 so that the vehicle's speed can be detected. If this sensor is not present, as explained above, the speed sensor must also be installed, the connections of which are connected to flat plug connection 3 and ground.

The negative pulses from the control unit (push button) are fed to the Startronic device via connector 5. The effects triggered by pressing the button depend on the speed of the vehicle (see points 1.2; 1.7 and 1.8).

Connector 6 supplies an output signal to the display element, which optically signals that the automatic switch-off is active after the next vehicle stop.

The ignition circuit is interrupted (on the power or control side, depending on the vehicle type) via the flat plug connectors 7 and 8, which are connected internally to the open contacts of relay K2, so that the engine stops. To do this, the ignition circuit is opened and connected to the flat plugs mentioned.

The flat plug connections 9 and 10 are internally linked to the open contacts of relay K3. This relay interrupts the current path of the low beam, which is also separated in order to be routed via the connections mentioned.

The connections 11 and 12 are directly connected to the coil of the power relay Kl. This relay initiates the starting process. Its closing contacts 30 and 87 are laid parallel to the starter switch via an additional line, so that when the relay is energized the starting process is triggered and when it is de-energized it is immediately interrupted.

-A- Functional description based on circuit diagram

3.1 General conditions

Modern vehicles have, among other things, catalytic converters, brake boosters and power steering.

To ensure that these devices always function properly and are maintained, the following conditions for the operation of engine shutdown systems must be strictly observed:

3.1.1 The frequent switching off of the engine may only take place after the operating temperature of the engine and the exhaust system has been reached in order to prevent damage to the catalytic converter.

3.1.2 The engine may only be switched off when the vehicle is stationary, as the units required to maintain the pressure in the hydraulic system for power steering and brake boosting are only operated when the engine is running and can therefore ensure the operational safety of the vehicle.

3.2 Description of the function

When the system is "on" and the ignition is switched on, +12 V is supplied to the fuse Fl via flat plug connection 1.

Connection 2 has a negative potential (-) or ground. The fuse Fl supplies both the Startronic device and the relays Kl; K2 and K3 with power. The CMOS ICs are only supplied with +5 V via V 7805 so that the inductive voltage peaks that occur in the on-board voltage range, e.g. during the starting process, which can lead to the destruction of the circuits, are avoided.

3.2.1 Conventional driving operation

When the toggle switch is set to "Off", the Startronic system does not receive any voltage, so that the relays K1 to K3 cannot be energized.

Both the open contacts of K2 and K3 ensure a constantly closed current path for the ignition system and any dipped beam that may be switched on. Initiation of the starting process via Kl is also excluded.

3.2.2 Shutdown system switched on
3.2.2.1 Warm-up phase

In modern vehicles, manufacturers place great importance on ensuring that the operating temperature is reached as quickly as possible. This is achieved by increasing the idle speed during the warm-up phase. The idle speed increase is also effective in other operating states, e.g. when the vehicle is "driving" or during the start-up process or when equipped with an air conditioning unit. This effectiveness will not be examined in more detail here, as it is of no importance for the shutdown system.

As long as the operating temperature of the engine and catalytic converter is not reached, the idle speed is between 1200 and 800 to 850 rpm.

-5-

When the engine is warm, the speed drops even further, by 750 rpm. The different physical principles that cause this idle speed increase will not be discussed here. What is important is that the speed of the negative pulse sequence in the ignition system decreases as the engine temperature increases.

This circumstance is exploited in the Startronic device so that when a minimum pulse speed is reached, e.g. at 800 rpm, the first condition for the switch-off option is fulfilled both automatically and by pressing the button.

3.2.1.2 Operational phase

The negative pulses of the ignition system are fed capacitively through Cl .3 to inputs 5 and 11 of 4528 Vl via connector 7. The incoming pulses are brought to a certain required length via the RC combination Pll - C1.1 and P1.2 - C1.2. The corresponding negative pulse lengths are effective at outputs 7 and 9. As long as a faster pulse sequence arrives at input 5, as is the case with the effectiveness of the idle speed increase, the total negative pulse time is quite high compared to the effective positive pulse time at output 7. Via R3.1, C3.1 and 4069 V3.1 and V3.2, the pulses from output 7 at output 4 of 4069 V3.2 are converted into an analog signal, the voltage magnitude of which is read in steps as an L or H signal at input 4 of 4023 V4.2.

At low engine speeds, it is defined as an H signal. This is a first condition that an L signal can be generated at output 6 of 4023 V4.2 or at output 9 of 4023 V4.3, which causes the engine to be switched off via 4044 V5.2 input 11.

The second condition for the engine to be switched off was that the vehicle was stationary. The on-board speed sensor delivers short L pulses depending on the speed, which are fed to the two inputs 5 and 11 of 4528 V2 via flat plug connection 4 using C2.3. The combination C2.1 - R2.1 stretches the pulses so that a level change at output 7 to H only occurs approx. 1s after the vehicle has come to a standstill. So as long as the speed sensor delivers L pulses, there is an L level at output 7 of 4528 V2 and thus at inputs 2 and 4 of 4023 V4.2 and V4.3. This means that L pulses at outputs 6 and 9 of 4023 V4.2 and 4.3, which would cause the engine to be switched off at 4044 V5.2 input 11, are excluded.

Automatic engine shutdown

The pulses from the speed sensor are also effective at input 11 of 4528 V2. The combination P2.2 - C2.2 brings these pulses to a defined length. Output 9 supplies an analog signal to input 7 of 4044 V5.4 via R5.4.2 - C5.4.2, which is evaluated as an L signal after a certain driving speed is exceeded (L component of output 9 increases). The driving speed at which this applies is set via P2.2. An activation speed of around 40 km/h has proven to be useful. 4044 V5.4 therefore assumes an H level at output 9, which it also maintains when the speed decreases again.

If the vehicle comes to a standstill, the engine is automatically switched off after approx. Is, because the 3 inputs 1; 2 and 8 of 4023 V4.3 have H level:

-6-

Output 4 of 4069 V3.2 due to low engine speed; output 7 of 4528 V2 due to vehicle standstill and output 9 of 4044 V5.4 due to exceeding the critical speed of 40 km/h

An L signal is generated at output 9 of 4023 V4.3. This causes 4044 V5.2 output 10 to assume H level. This leads to

- Transistor VO.2 is switched through and K2 is excited and the ignition circuit at the plug connections 7 and 8 is interrupted

- from 4069 V3.4 to inputs 4 and 6 of 4044 V5.3 and 5.4 L level is applied. As a result, outputs 13 and 9 also assume L level, so that output 10 of 4069 V3.5 is H level. Transistor VO.3 is switched through, K3 is excited and the current path for the low beam is interrupted via connections 9 and 10.

Manual shutdown

If the critical speed is not reached, the L level remains at output 9 of 4044 V5.4, which the output had at the time the engine was last switched off. Input 8 of 4023 V4.3, which has the L level, prevents automatic switching off after the vehicle has stopped and despite low engine speed. However, the engine can be switched off by pressing a button.

An L signal from the button is applied to input 5 of 4069 V3.3 via flat connector 5, so that the output 6 is immediately at H level. The L signal coming from the button only has a delayed effect on input 5 of 4023 V4.2 due to R4.2.2 and C4.2, so that all 3 inputs 3, 4 and 5 are briefly at H level, which triggers an L pulse at output 6. This affects the input of 4044 V5.2 and triggers the shutdown process described above.

Reactivation of automatic shutdown

If 40 km/h is exceeded, the automatic shutdown is activated. This is indicated visually by an LED whose current path is closed by the switched transistor V0.4 (with 4044 V5.4 output 9 = H). The activated automatic system can be reset by pressing a button at a driving speed between 0 and 40 km/h, as the L signal from the button is fed to input 6 of 4044 V5.4 via flat plug input 5 via diode V5.4.1. After the vehicle has stopped, the engine remains on, but can be switched off by pressing the button again (if necessary). The reactivation is immediately canceled if 40 km/h is subsequently exceeded again.

As discussed at the beginning, if there is no on-board speed sensor, a speed sensor from the VDO cruise control must be retrofitted, whose sinusoidal alternating voltage signals are initially unsuitable for internal evaluation. Its signals, which are directly proportional to the driving speed in amplitude and frequency, are converted into a suitable form via the PO.5 - VO.5 system, so that square-wave pulses such as those from flat plug input 4 are available. The speed sensor is connected to flat plug input 3 and

-7-Minus (ground) connected.

Motomeustart

When the engine is stopped, the H level is present at output 10 of 4044 V5.2. The same level is present at input 11 of 4023 V4.1 approximately 1.2 to 1.3 s after the engine has stopped. This time delay is the result of the combination R4.1.1- C4.1.1. The delay is necessary so that the restart cannot be triggered immediately after the engine stops. The starter pinion would then mesh with the drive ring gear, which is still moving due to the engine briefly running down, which would lead to extremely high levels of wear on the starter system.

After this time delay has elapsed, the start process can be triggered by pressing the button.

This means that all 3 inputs 11; 12 and 13 of 4023 V4.1 are briefly at H level via output 12 of 4069 V3.6 and the combination of R4.1.2 and C4.1.2, and therefore an L pulse is generated at output 10. As the missing pulses at input 11 of 4528 Vl mean that the engine or ignition is "off" and the H level is at input 14 of 4044 V5.1, the L pulse at input 15 of 4044 V5.1 sets output 1 to H level. The same L pulse simultaneously causes an L level at input 12 of 4044 V5.2 at its output 10.

This closes the engine ignition circuit again. In addition, transistor VO. 1 is switched through and the start relay Kl is energized. The starting process is triggered by closing relay contacts 30 and 87. As long as the engine is only moved by the starter (approx. 150 to 180 rpm), the frequency of the ignition pulses that are applied to input 11 of 4528 Vl is also low. With a low pulse sequence, the temporal L component of the output pulses at output 9 of 4528 Vl is low, so that due to the combination R5.1 - C5.1 there is still a clear H signal at input 14 of 4044 V5.1. A clear increase in frequency can be seen when jumping from the starting process (150 to 180 rpm) to the engine running automatically (lower speed limit 750 rpm). The L component at output 9 of 4528 Vl is significantly higher and can no longer be intercepted by the R-C combination at input 14 of 4044 V5.1. This means that L is read at input 14 and output 1 also assumes L level. The transistor VO.1 becomes high-resistance and the start relay Kl is de-energized. The starting process is interrupted when the higher engine speed is detected by self-running. Since the L level is constantly present at input 14 of 4044 V5.1 while the engine is running, it is impossible to initiate the starting process during this time. As soon as this input 14 assumes L level, input 3 of 4044 V5.3 also assumes L level. Because of 4044 V5.2 output 10 = L (ignition path closed) there is an H level at input 4, its output 13 also assumes an H level because of L at input 3. 4069 V3.5 output 10 switches transistor V0.3 to high resistance. Relay K3 is de-energized. This closes the current path for the low beam again after the start-up process has taken place.

Measures to stabilize the switching behavior and to ensure defined signal levels at the circuit inputs are not discussed in this context because explanations of this are not necessary for general understanding.

Claims (4)

-8-Protection claims Stop-start automatic system Startronic type SK 12 / 06 for car engines, which can be retrofitted in any car with a petrol engine with manual transmission, characterized in that 4.1 the possibility of switching off the engine manually or automatically without subjective human influence is only available after the engine operating temperature has been reached; 4.1.1 the reaching of the operating temperature is not signalled by a temperature sensor but rather the criterion of the decreasing idle speed and the associated lower ignition pulse frequency is used internally as a secondary effect of the increase in the operating temperature; - this saves an additional temperature sensor and does not interfere with the existing on-board system, 4.2 switching off the engine, both automatically and via the control unit, is excluded at a driving speed > 0; 4.2.1 the implementation of point 4.2 is carried out by resorting to proven systems (retrofitting the speed sensor of the VDO cruise control) or using the existing on-board speed sensor, the pulse signals of which are fed capacitively to the Startronic device so that a galvanic connection with the on-board system is avoided; 4.3 an automatic engine stop is activated after exceeding a certain speed, adjustable between 20 and 60 km/h, after the vehicle has come to a standstill (automatic switch-off); 4.3.1 as a warning function, an optical display is provided that if the activation speed is exceeded and the vehicle then comes to a standstill, the engine will be switched off automatically; 4.4 When the control unit (button) is pressed, different functions are triggered depending on the current speed of the vehicle: - Engine stop at speed 0 - Resetting the activation of the automatic switch-off below the set activation speed and above 0 km/h - approx. 1.2 s after engine stop, restart process is initiated; 4.5 the automatic interruption of the starting process occurs above 600 rpm engine speed - this ensures that the engine is running automatically; false starts when the button is pressed are excluded, regardless of how long the button is pressed; 4.6 the automatic switching off of a main consumer (dipped headlights) during the time the engine is stopped until the next automatic start of the engine (i.e. also until the start-up process is completed) is effective to relieve the load on the battery; -9- 4.7 conventional driving operation is ensured without complications by switching off the device; 4.8 the control functions listed in points 4.1 to 4.6 are ensured by using simple logic modules and their connection as shown in the circuit diagrams.