SE502154C2 - Method and apparatus for selective use of exhaust brakes in connection with gearing up - Google Patents

Abstract

The microprocessor control unit is connected by signal lines to devices controlling the fuel system, retarder and antilock (ABS)/antislip (ASR) braking system. It responds to a braking program switch near the driver's left foot, a clutch-pedal switch and sources connected to the transmission mode selector lever, economy/hillclimb mode selector, retarder coolant thermometer, gearbox output shaft tachometer etc. The use of engine braking depends upon whether the braking program switch is engaged so as to raise the normal gear-change point, and whether the loss of speed during the change exceeds a predetermined threshold dependent upon the mode of operation (kickdown).

Description

10 15 20 25.-30 35 502 154 power, preferably by applying the exhaust brake, in gears where fast gears are required. As a result, the increased engine braking power, preferably through the activation of the exhaust brake, and sound generation when shifting for the vast majority of gears can be limited. The disturbing noise for drivers, passengers and the environment is reduced. Yet another breath is that when shifting performance is really needed, it is automatically available depending on current vehicle parameters, without the driver having to take any further action.

Another breath is that the wear on the engine and its parts, mainly the turbocharger in supercharged engines, can be reduced.

For these purposes, the invention is characterized in a method according to the characterized part of claim 1.

Another object is to reduce the wear on the exhaust brake mechanism. By selectively using the exhaust brake when shifting up, the exhaust brake is used only for a fraction of the total number of gears relative to what would otherwise be relevant with a regular exhaust brake activation when shifting up.

For these purposes, the invention is characterized according to the method according to the characterized part of claim 2 and according to the device according to the characterized part of claim 8.

An object in a further developed embodiment is to quickly obtain transmission with activated exhaust brake only in the essentially two operating situations where either; - a gearbox can be lost due to the vehicle deceleration being too high during the shifting process, which applies mainly on steep uphills, or - an engine brake failure caused by the gearing must be poured briefly, which applies mainly on steep downhills.

In this way, during normal operation of, for example, a truck in remote distribution, the activation of the exhaust brake and sound generation when shifting can be limited to between 5-10% of the total number of gears required.

For these purposes, the invention is characterized methodically according to the characterized part of claim 3.

An object in a further further developed embodiment is that in operating situations where a gear ratio can be lost due to the vehicle deceleration being too high during the gear change process, different strict assessment criteria are used for automatic activation of the exhaust brake during gearing. Depending on the driver's actions, exhaust brake activation is automatically obtained when shifting even at lower deceleration levels when the driver has activated a reverse program or pressed the accelerator pedal in the bottom in a so-called kick-down position, but in normal operation without activating kick-down or reverse programs is obtained automatic exhaust brake activation when shifting up only at higher deceleration levels and if a shifting up to a lower gear, preferably in the bearing part of the gearbox, is relevant.

For these purposes, the invention is characterized methodically according to the characterized part of claim 4 and 5, respectively, and with regard to the specific deceleration limits for the respective driving case according to the characterized part of claim 6 and 7, respectively. Other features of the other invention appear from the dependent claims as well as the following description of an exemplary embodiment in which reference is made to the following figures.

Drawing list Fig. 1 shows a basic structure of a shift system for mechanical step gears, Fig. 2, shows a flow chart of how the control unit detects the vehicle parameters which result in selective activation of the exhaust brake during shifting.

Description of exemplary embodiments Figure 1 shows a shifting system for monitoring and controlling computer-assisted shifting of mechanical gearboxes in a motor vehicle. The vehicle is driven by an internal combustion engine 40, preferably a diesel engine, which via a driver-actuable clutch 41 can transmit the driving force to the vehicle's drive wheel 44 via a mechanical step gearbox 42 and propeller shaft 43. The gearbox 42 preferably comprises an integrated retarder 48 with an adjustable retarder brake. on the driveline in order to provide a high braking effect on the vehicle without using the vehicle's ordinary service brakes.

The shift system in the exemplary embodiment comprises a manually operated clutch servo for start and stop but lacks an automatic clutch servo, but the invention can also be applied in systems with an automated clutch.

The gear system performs the gears by regulating the engine speed and engine torque at the gears and operating the servo which shuts off the existing gear and shifts into the next gear without disengaging the clutch 41.

This places high demands on the motor control and the speed information that the system requires in order for the motor control to enable a torque-free deployment of a gear and by the motor control alone to quickly obtain synchronous speed for the next gear which must be engaged with the shortest possible torque interruptions. the mechanical step gear.

Mechanical step gearboxes, preferably with or without conventional synchronizing devices in the gearbox, are from many points of view a much more advantageous choice than conventional hydraulic automatic gearboxes that shift without torque interruptions, or mechanical crates with complicated double clutches which should enable shifting without torque interruptions. This is mainly from a cost point of view in terms of operating finances, service and purchasing cost. If the step gearbox also includes conventional synchronisations, an increased reliability is also obtained when a manual shift or a semi-automatic shift, ie servo-assisted disengagement and loading of gear as a result of manual disengagement, can be performed if the automated shift function has been lost due to system failure. a high changing comfort.

The changeover system comprises a control unit 12 with microcomputer which is connected with different signal lines 36 to control units for fuel system 23, retarder system 22 and the vehicle brake system 24. On the signal lines different signals are transmitted to the control unit 12 corresponding to the arrows damaged 1-11,13-19,21 and 59 in Figure 1.

The control unit 12 receives the following inputs; -Signal 1 from a brake program switch 27 which is arranged accessible for foot impact from the driver.

The brake program contact affects the retarder function via the control unit 22 but also the changeover points of the shift system when the brake program contact is activated.

Signal 2 from clutch contact 30 which detects the position of the clutch pedal.

-Signal 3 from the vehicle's foot brake pedal indicating the position of the brake pedal.

-Signal 4 from the vehicle tachograph with secondary information about the vehicle speed or PTO shaft speed.

-Signal 5 from the vehicle's accelerator pedal indicating the current accelerator pedal position.

Signal 7 from an exhaust brake switch 45 arranged on an instrument panel 32.

-Signal 8 from the gear lever, indicating the operating state of the gear system selected by the driver, either in automatic mode A, neutral mode N, manual mode M or reversing R and any corrections made by the driver of automatically selected gear or new gear selections in automatic mode A or any manual mode N, M , R.

-Signal 9 from a driving program selector 26 where the driver can choose for example economy program E, which gives change points with the best fuel economy and soft changes, or reverse driving program H where the change points are set so that maximum traction can be obtained and where the speed of the change is prioritized before comfort and sound.

Signal ll from a diagnostic switch 35, with which a test program built into the control unit's software can be activated for service or fault location by means of an error message on the instrument panel information field 33.

-Signal 21 from the retarder control unit 22, which modifies the changeover points as long as the signal from the retarder function is activated in order to obtain increased engine braking power and coolant flow.

Signal 19 from a speed sensor arranged on the output shaft 42 of the gearbox 42, preferably the cardan shaft 43.

Signal 18 from acknowledgment contacts in the gearbox 42, which indicate which gear is engaged.

Signal 16 from a speed sensor arranged on the input shaft of the gearshift 42 42, preferably on the crankshaft or flywheel of the engine.

Signal 59 from a temperature sensor 49 which senses the temperature of the cooling water leaving the retarder.

The controller 12 controls various servos or turns on information fields on the instrument panel 32 with the following outputs; -Signal 6 is sent to an information field 33 on the instrument panel 32 where the gear system operating condition (A-N-M-R), current gear, next gear, driving program (E-H), as well as any error codes, warnings and information to the driver are indicated.

-Signal 17 is sent to various solenoid valves in the gearbox which activate the servo for actuating the shift driver so that gears can be pulled out or skated.

Signal 15 is sent to the exhaust brake 58 which is arranged in the engine's exhaust system, so that the exhaust brake in addition to its function as an auxiliary brake can be activated for rapid reduction of the engine speed to synchronous speed, mainly when shifting to a gear with a lower gear ratio.

The control unit 12 is also in a two-way connection, ie sends output signals and receives input signals from a plurality of control units via the links; -Link 10 connected to the diagnostic socket 34, where a diagnostic equipment can drain error codes from the control unit 12 and perform software control of the control unit's function.

-Link 13 connected to the control unit for the brakes' anti-lock function (ABS) and anti-slip function (ASR), where the brake unit's control unit can, among other things, prevent shifting when the ASR function is active.

Link 14 is connected to the control unit 23 of the fuel system, which in turn via the link 20 regulates the amount of fuel of the injectors of the internal combustion engine.

In the above system, the shift in the A position of the gear lever can be operated automatically depending on detected engine parameters such as vehicle speed, engine load and speed, derivative of any or a combination of vehicle speed-accelerator position-engine speed, if the accelerator pedal is depressed at the bottom (so called kick-down) and whether a braking occurs. The shift is performed automatically so that optimal fuel consumption and performance are obtained.

The retarder control unit 22 comprises a manual control 61 which is preferably arranged on the instrument panel 32.

The control can be set in a number of positions O-V, where the initial position 0 means that the retarder 48 is switched off and positions I-II-III-IV and V give a progressive increase in the braking effect of the retarder. Position I can give a braking torque of 500 Nm, Position II - 1000 Nm, Position III - 1500 Nm, Position IV - 2000 Nm and position V maximum retarder braking power around 3000 Nm. The last braking power stage V suitably also comprises a simultaneous activation of the vehicle's exhaust brake 58 / EB which further increases the braking effect on the vehicle's drive wheels. The positions 0-V are stable, which is why the lever remains in the respective position if the driver releases the lever.

However, the retarder function is always switched off as soon as the driver acts on the vehicle's accelerator pedal 31, but the brake effect of the retarder is automatically switched on as soon as the accelerator pedal is released and the control is in position I-V.

The retarder function can also be switched on as a constant cruise control function depending on the brake pedal action or the action of a button 63 on the control 61. The brake effect of the retarder is then regulated automatically so that the vehicle's speed is sought to be maintained by progressively increasing the braking effect. Through the button 62, this constant speed inclination function can enter automatically as soon as the brake pedal 29 is activated, and remain activated as long as the accelerator pedal is not activated thereafter.

The invention is advantageously applied to automatic shifts of mechanical step gearboxes, where the shift is performed without the clutch 41 being disengaged.

The invention is described in more detail with reference to Figure 2, which figure shows a flow chart for a control routine for selective activation of the exhaust brake in dependence on vehicle parameters indicative of the need for rapid upshifts. The control routine is stored in the microcomputer of the control unit 12.

In a first question step 80, it is checked whether upshifting is relevant. As long as gearing is not current, the program returns to the main program. The control routine can preferably be in a program loop that is run through at a frequency of 100 HZ (Hertz). Checking whether upshifting is relevant is thus done 100 times per second.

If gearing is relevant, the control routine proceeds to interrogation step 81, in which it is detected whether a first condition for obtaining fast gearings by exhaust brake activation is met.

If the driver via the driving program selector 26 activated a driving program (Sprg = Shift program) for hill driving or if the driver pressed the accelerator pedal 31 at the bottom in a so-called kick-down position, the first part of the first condition is fulfilled. This first part states that there is a need to change gears quickly, on uphill slopes where a drive interruption caused by the shifting process can cause the vehicle to lose speed and miss a gear or in emergency traffic situations where the driver wants a quick response from the vehicle. In these cases, a second sub-condition is used to use the exhaust brake during the shift, which second sub-condition is the vehicle deceleration or velocity loss (dV = delta velocity) of the vehicle during the shift process. When this vehicle parameter, the vehicle deceleration or the speed drop dV of the vehicle, is above a predetermined value, the second sub-condition is fulfilled.

If both sub-conditions of the first condition in step 81 are met, the control routine for step 84 activates the exhaust brake E-mfuft during the upshift process.

The threshold value of this vehicle parameter dv is suitably set strictly so that the vehicle loses speed, dV <0, whereby the exhaust brake is automatically activated during the shifting process if the vehicle should lose speed during the shifting process. Only if the vehicle does not lose speed, which could happen downhill with a forgotten activated reverse program or activated kick-down, the exhaust brake is not activated, which is also not necessary if the vehicle does not lose speed so that the vehicle's speed can be reduced below the gear point and gear ratio. thereby would disappear.

If any or both of the first and second sub-conditions are not met in the first condition of step 81, the control routine proceeds to step 82 in which it is detected whether a second condition for obtaining rapid upshifts by exhaust brake activation is met.

If the next gear (NG = next gear) that the control unit is to shift up to is lower than a predetermined gear EBgær, the first part of the condition is fulfilled. This first part states that upshifting shall take place to a lower gear of the total number of gears. Preferably, the next selected gear consists of a lower gear below the upper half of the total number of gears, preferably a current gear in the bearing portion of the gear carriage. In the low-range part of the gearbox are all the lower gears which are engaged when starting the vehicle and which are thereby very tightly stepped, with relatively small increases in gear ratio. These lower gears are normally in very short intervals, and upshifting can be prevented or quickly followed by a nerve shift if the vehicle loses speed so that the vehicle's speed can be lowered below the shift point or lowered below the nerve shift point for the next higher gear in the low-range section.

When shifts within the relatively closely stepped part of the gearshift, preferably the low-range part, are relevant, a second sub-condition is used to use the exhaust brake during the shift, which second sub-condition is the vehicle deceleration or speed loss of the vehicle during the shift process.

When this vehicle parameter, the vehicle deceleration or the speed loss of the vehicle, is above a predetermined value, the second sub-condition is also fulfilled and the control routine then proceeds to step 84 and activates the exhaust brake Eßwßmit during the shifting process.

The threshold value of this vehicle parameter dv is suitably set less strictly than the threshold value of the second sub-condition in the first condition in step 81. Only when the vehicle is subjected to a significant deceleration or velocity drop during the shifting process, detected by the PTO shaft Crpm, dV <-5 rpm / s <-5 rpm the second condition.

If both sub-conditions in the second condition in step 82 are met, the control routine to step 84 is fulfilled and activates the exhaust brake Eßmmmit during the upshift process, whereby the exhaust brake is automatically activated during the upshift process if the vehicle shifts up to a lower gear in the gearshift part of the gearbox. , and would essentially lose momentum during the shift process. If any or both of the first and second sub-conditions are not fulfilled in the second condition in step 82, the control routine says to step 83 in which a third condition is obtained for obtaining fast upshifts by activating an engine braking program is met.

If an engine braking program is activated, for example by the driver's influence on the brake program switch 27, an automatic activation of the exhaust brake is obtained during the shifting process. The engine brake program results in the gear points being raised and the exhaust brake applied as long as the contact 27 is depressed, but where only elevated gear points remain after the contact 27 is released and as long as the accelerator pedal 31 is not actuated thereafter.

When activated Engine Brake program (EnB = Engine Brake) is present, detected by the vehicle parameter elevated gear points, says the control routine to step 84 and activates the exhaust brake EBwmhi fl during the gearing process, whereby the exhaust brake is automatically activated during the gear cycle if the vehicle is engine braked. Activated engine braking program indicates that the driver wants extra braking power, and that all torque interruptions and the thereby lost engine braking power are as short as possible.

If the condition is not met in the third step 83, the control routine tells step 85 in which the exhaust brake uses EBwßhi fi during the upshift process (off). which is caused by the upshift must be poured so that deceleration is deactivated or the speed loss is detected as either actual acceleration or actual speed loss.

The acceleration is suitably detected in a calculation routine located in the program loop that is run through at a frequency of 100 Hz (Hertz). A short time base of 0.5 seconds was used, during which time the acceleration is determined. The acceleration is then updated 100 times per 10 15 20 25 30 35 5o2_154 13 seconds, and the acceleration value is stored in the memory of the control unit, from which the value is retrieved in steps 81 and 82 to determine whether the deceleration condition is met.

However, the acceleration value tends to be strongly affected by oscillations in the vehicle's driveline, whereby an anxious signal with varying value of acceleration / deceleration is obtained even if the tendency is a deceleration. Alternatively, the speed at the time of start of the transmission can be stored in the memory of the control unit, and in steps 81 and 82, a comparison with the current speed can be made to determine whether the speed loss is higher than the predetermined threshold value.

The control routine 80-84 / 85 is run continuously during the shifting process, and if, for example, the deceleration of the vehicle during the initial stage of the shifting does not exceed the predetermined threshold values, a later exceeding may result in the exhaust brake being activated during one and the same shifting. The activation of the exhaust brake suitably takes place as a hysteresis function, where the activation of the already activated exhaust brake does not take place during the activation of the exhaust brake for control over the synchronous speed, until the threshold values are below a predetermined offset value. Alternatively, a time function may block a cut-off of the exhaust brake due to falling below the threshold values during the shifting process, which time function preferably keeps the exhaust brake switched on for preferably 50 milliseconds, and only then allows a cut-off due to underscoring the threshold. However, a release of the exhaust brake in order to obtain / obtain synchronous speed through the activation of the exhaust brake always takes precedence over the hysteresis function.

The preferred threshold values for the deceleration condition are suitably adapted to the response of the shift system. 10 15 20 25 30 35 502 154 14 Faster response in the servo for shifting, shifting, exhaust brake activation and fuel control means that the threshold values can be set at higher decelerations without the torque interruption due to the shift becoming too long to risk a gear being missed or the engine braking effect disappears for too long.

The adjustment of the threshold values can also take place in order to further reduce the use of the exhaust brake for gear changes, by setting higher deceleration conditions, or in order to obtain faster gears more often, by setting lower deceleration conditions. Additional logical conditions can also be introduced for the same purpose.

The predetermined threshold values are stored in a non-volatile memory 57 in the control unit 12.

The invention can be modified within the scope of the claims so that differences with respect to the preferred embodiment are obtained. The unique thing about the invention, however, is a selective use of an engine braking means acting on the engine gas change for amplification of the engine braking power, preferably by activatable exhaust brake, in gears in gearboxes for mechanical gearboxes, which use occurs automatically due to exceeding predetermined vehicle parameters. vehicle parameters indicate that short torque interruptions and rapid shifts are required, either because there is a risk of losing a gear ratio or that interruptions in engine braking power must be reduced at times when extra braking power is ordered by the driver.

By engine brake means affecting the gas exchange of the internal combustion engine is meant in addition to the exhaust brake also selectively activatable engine brake means of 10 15 20 5o2A1s4 15 - "Jake-Brake" type, which by short-term opening of the exhaust valve at ÖD (Upper dead center on the piston) of the work of the compressed air on the piston during the movement of the piston down from the OD (ie prevents rebound), and engine brake means where a short-term opening of the exhaust valve at ND (Lower dead center on the piston) before the compression stroke fills cylinder with exhaust gases with elevated pressure, increased compression work and thus increased engine braking effect, as well as combinations of the above two engine brake functions possibly combined with an exhaust brake.

With the Jake brake, for example, a pneumatic cylinder can depress an exhaust valve, on some or all cylinders, cyclically at the OD during the neutral phase when elevated gear points are present or the vehicle deceleration during shifting is too high. Correspondingly, the exhaust valve can be opened at ND to fill the cylinder with exhaust gases before the compression stroke during the neutral phase when elevated gear points are present or the deceleration of the vehicle during the shift is too high.

Claims (8)

10 15 20 25 30 35 502 154 16 Patent claims 1. l. Procedure for automatic computer-assisted shifting systems for mechanical stepper gearboxes in internal combustion-powered vehicles in connection with shifting from a current gear unit where an engine braking means acting on the engine gas shift is activatable to amplify the engine braking power to quickly reduce engine speed to a speed which is synchronous with the next gear, characterized in that the engine braking means is selectively activated during shifting depending on whether a vehicle parameter is above a predetermined value. A method according to claim 1, wherein an exhaust brake is activatable to quickly reduce the engine speed to a speed which is synchronous with the next gear, characterized in that the exhaust brake is selectively activated when shifting depending on whether a vehicle parameter is above a predetermined value. 3. A method according to claim 2, characterized in that the exhaust brake is selectively activated when shifting depending on - if an engine braking program is activated which results in elevated shift points relative to predetermined normal shift points, or - if during the shift process the vehicle deceleration or speed loss is over threshold value. Method according to Claim 2 or 3, characterized in that the exhaust brake is selectively activated during shifting depending on whether the deceleration of the vehicle is above a predetermined first threshold value during the shifting process while the driver depresses the accelerator pedal in a kick-down position, or a control for activating a 10 15 20 25 30 35 so2 1s4 17 reverse run program has been affected. Method according to claim 2 or 3, characterized in that the exhaust brake is selectively activated when shifting depending on whether the deceleration of the vehicle is above a predetermined second threshold value during the shifting process while the next selected gear is a lower gear during the upper half of the total number gears, preferably a current gear in the bearing part of the gearshift. 6. A method according to claim 4, characterized in that the predetermined first threshold value constitutes a vehicle deceleration lower than 0 m / sz. A method according to claim 5, characterized in that the predetermined second threshold value constitutes a vehicle deceleration corresponding to a velocity drop, detected by the PTO shaft Crpm, lower than -5 Crpm / s. Device for controlling the execution of automatic transmission in computer-aided transmission systems for mechanical stepper gearboxes in motor vehicles where the gears are discharged and loaded by means of servo devices in the gearbox at the same time as motor control according to programs stored in a control unit (12) vehicle parameters detected by the control unit (12) such as via at least one speed sensor (47) arranged to detect the speed of the vehicle (46), and where an exhaust brake (58) arranged in the exhaust system of the engine (40) is selectively activated by the control unit (12) during the upshift process driving case to reduce the engine speed to the synchronous engine speed for the next higher gear 10 15 20 25 502 154 18 characterized in that the control unit (12) comprises, -means (12.8l, 82.83) for detecting the type of driving case, indicated via setting the travel program selector (26) in reverse travel mode (hill), actuation of the accelerator pedal (31) in the kick down position, shifting to one gear among the lower gears of the gearbox, or via brake program switch (27) activated engine braking program resulting in elevated gear points, means (l2,81,82,46) to detect if the vehicle speed decreases during the gear, means ( l2,57) for storing predetermined threshold values for speed reductions, means (l2,8l, 82) for determining whether the vehicle speed during the shift has fallen below a predetermined threshold value, - means (l2,8l, 82,83,84) for activating the exhaust brake (58) during upshift to reduce the engine speed to the synchronous engine speed for the next higher gear if the vehicle speed has fallen below the threshold when the driving program selector (26) is in reverse mode (hill), the accelerator pedal (31) is in kick-down mode or to a gearbox among the lower gears of the gearbox shall take place, or if the activation of the brake program switch (27) has resulted in elevated remaining gearing points.