SE502151C2 - Method and apparatus for influencing gear points in response to activated motor braking programs - Google Patents

Abstract

The microprocessor control unit is connected by signal lines to devices controlling the fuel system, retarder and antilock/antislip braking system. It responds to a braking program switch near the driver's left foot, a clutch-pedal switch and sources connected to the economy/hillclimb mode selector, retarder coolant thermometer, gearbox output shaft tachometer, transmission acknowledgement switches etc. With the switch held closed, down- and up-change points are raised above the prim. predetermined engine speeds. When it is released the down-change points fall until both gps. of points are reset by further operation of the accelerator.

Description

15 20 25 30 35 502 151 2 depending on transitions from a state in which the engine drives the vehicle, to a state in which the fuel supply of the engine is interrupted and thus engine brakes, and further to a state in which braking of the vehicle is activated by the driver, and a reverse transition between these conditions, where the number of downs and gears is limited and excessive changes in braking power are not obtained.

An essential object is to obtain smoother transitions with respect to applied braking power levels between states where the driver has only released the accelerator pedal, at which state the driver still accepts that the vehicle on a downhill can increase its speed, to states where different degrees of braking have been used. that the accelerator pedal has subsequently been reactivated.

Another object is to have a logical connection between gears made to get maximum engine braking power as long as the vehicle's speed increases, and to make shifts without aiming to get maximum braking power as long as the vehicle's speed decreases, as long as the accelerator pedal is not reactivated after a brake contact or pedal has previously been activated temporarily.

A more economical driving of the vehicle is obtained automatically as a logical consequence of a activation sequence of the vehicle's control selectively performed by the driver, without braking torque being obtained when the vehicle loses speed, which must be compensated with increased fuel input when the vehicle returns to original cruising speed.

For these purposes, the invention is characterized according to the method according to the characterized part of claim 1 and according to the device according to the characterizing part of claim 8. Other objects and features of the invention will become apparent from the following description of an exemplary embodiment and the appended claims. 10 15 20 25 30 35 .soz 1.51 ._ 3 The invention is not limited to automatic shifting of mechanical step gearboxes, but can also be applied in other types of gearboxes such as hydraulic automatic gearboxes.

List of drawings Fig. 1 shows a basic construction of a gear system for mechanical step gearboxes.

Fig. 2, shows a shift point diagram where the vehicle parameter-dependent shift points are in principle represented.

Description of exemplary embodiments Figure 1 shows a shifting system for monitoring and controlling computer-aided 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 wheels 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 shifting 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 automated clutch.

The shifting system performs the shifts by regulating the engine speed and engine torque at the shifts 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 obtain a synchronous speed for the next gear to be engaged with the shortest possible torque interruptions in the mechanical 10 15 20 25 30 35 502 151 step gearbox.

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 boxes 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 as a manual shift or a semi-automatic shift, ie servo-assisted laying and shifting of the gear as a result of manual disengagement, can be performed if the automated shift function is 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 signaled signals 1-11, 13-19,21 and 59 in Figure 1.

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

The brake program switch affects the retarder function via the control unit 22 but also the changeover points of the shift system when the brake program switch 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. 10 15 20 25 30 35 .soz 1.51 5 -Signal 4 from the vehicle tachograph with secondary information on 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 position 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 of the gearbox 42, preferably the PTO 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 gearbox 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. 10 15 20 25 30 35 502 151 6 The control unit 12 regulates various servos or turns on information fields on the instrument panel 32 with the following output signals; -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 influencing the shift driver so that gears can be pulled out and slid in, respectively.

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 lowering 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 checks 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 brakes' control unit switching when the ASR function is active.

Link 14 is connected to the fuel system control unit 23 which in turn via the link 20 regulates the amount of fuel of the pre-combustion engine injector.

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 the vehicle speed, engine load and speed, the derivative of any or a combination of vehicle speed-accelerator pedal position. engine speed, if the accelerator pedal is depressed at the bottom (so-called kick-down) and if braking takes place. 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 0-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 provide 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 retarder's braking effect is automatically switched off 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 speed inclination function depending on the brake pedal effect 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 maintained by progressively increasing the braking effect. Through the button 62, this constant speed 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.

Figure 2 shows in principle the downshifting and shifting points that the control unit 12 uses to determine new gears. The X-axis shows the PTO shaft (C.RPM) 10 15 20 25 30 35 502 151 8 'and the Y-axis reproduces the engine speed (E.RPM). These speeds detect the control unit 12 through the sensors 46 and 47, respectively.

ND, Normal Downshift, denotes the normal nerve exchange points between gear 12-ll (G12-G11), gear ll-10 (G11-G10) and gear 10-9 (G10-G9).

NOW, Normal Upshift, denotes the normal upshift points between G9-G10, G10-G11 and G11-G12.

In a corresponding manner, shift points are also set for lower gears and possibly higher gears (not shown).

The normal down and upshift points ND and NU are of course affected by current vehicles and engine parameters such as vehicle acceleration, accelerator pedal speed, accelerator pedal acceleration, and any kick-down position, but the damaged shift points can be considered representative of a continuous mode and throttle load.

In a manner known per se, the down and downshift points are automatically raised from the normal shift points ND and NOW to significantly higher shift points EBD (Engine Braking Downshift) and EBU (Engine Braking Upshift) when the driver affects a special engine brake switch 27. This engine brake switch 27 may preferably be placed on the floor next to the vehicle's regular floor pedals for clutch 28, brakes 29 and accelerator pedal 31. By using a separate engine brake switch 27 to activate an engine brake program, which does not use the vehicle's friction brakes acting on each individual wheel, the friction brakes are saved. This provides increased safety and extended service life of the vehicle's main brakes, as the vehicle's friction / travel brakes only need to be used in the event of more severe and urgent braking needs.

The engine braking program mainly includes an increase in the shift points, which means that greater braking power can be taken out of the engine. The engine brake program can also cause an exhaust brake 49 to close in order to further increase the engine brake power. With a retarder system 22, which can use a hydrodynamic or electric retarder acting on the vehicle's driveline, possibly with the retarder integrated in the gearbox, the retarder can also be switched on with activated engine braking program to increase the braking effect.

The elevated shift points EBD and EBU for both downshift and upshift are maintained as long as the contact 27 is kept depressed by the driver. In the control unit's software, a flag / rocker is set to the active position as a direct result of the switch 27 being pressed down.

When the driver then releases the switch 27, only the nerve exchange points return from their elevated positions EBD to their normal positions ND. If the vehicle in this position, after the driver has released the contact 27, is on a downhill slope which causes the vehicle to tend to increase its speed, an increased braking effect will be taken out of the engine, compared to if the gear points also returned to the normal positions, in and with the elevated gear points remaining.

If the vehicle in this position, after the driver has released the contact 27, is instead on an uphill slope or has a road load which means that the vehicle tends to lose its speed, the current gear will remain for a longer time before nerve change is performed, which gradually decreases engine braking power and lower engine speed. With decreasing vehicle speed, it is not necessary for the engine braking effect to increase with decreasing speed.

Alternatively, the nerve shift points can be lowered from their elevated positions EBD to a lower position which, however, is above the normal position ND, when the driver releases the contact 27.

Due to this influence on the changeover points, maximum braking effect is obtained regardless of whether the vehicle loses speed or increases speed as long as the driver keeps the contact 27 depressed.

When the contact is released, enhanced braking power is obtained through increased gear points as long as the vehicle's speed increases, while the braking power decreases through return to normal nerve gear points if the vehicle loses speed.

The elevated upshift point EBU remains as long as the flag / rocker in the control unit's software is set to an active position. Resetting the flag in a passive position only takes place when the accelerator pedal is again actuated, after which the shift points are lowered to the normal shift points NOW.

Through the described method for influencing the shift points, a more user-friendly control logic is obtained for the shifts, which logically retain increased engine braking power if the vehicle tends to increase the speed even after the brake contact 27 has been released. The driver thus does not have to pour his foot on the contact under a long downhill slope, where the braking effect increased by the elevated gear points is sufficient to avoid the vehicle's speed increasing or only increasing to a limited and acceptable extent. The number of shifts directly as a result of the brake contact 27 being activated and deactivated is reduced, as only a required number of nerve changes take place as a direct result of the contact 27 being depressed due to elevated shift points, since a released contact does not in itself result in a corresponding number of shifts. return to normal switching points. Only when the accelerator pedal is still activated does a full return to normal changeover points take place.

This is particularly advantageous when driving on long downhill slopes, where the driver has released the accelerator pedal and the vehicle is allowed to increase, decrease or maintain its speed to an extent determined by the driver. As long as 10 15 20 25 30 35 5o2_151 ll V brake contact 27 has been activated without the accompanying accelerator pedal activation, the shift system assumes that a certain braking need can remain, so the elevated gear points remain which, however, only affect the vehicle if the speed increases. If, on the other hand, the speed of the vehicle decreases, no earlier nerve changes take place in order to increase the braking effect from the engine. The control logic for the gears then becomes logical with regard to gears for increased braking power as long as the vehicle's speed increases, but obtains gears without the braking power being maintained as long as the vehicle's speed decreases. However, the driver can easily remove the raised gear points obtained by impacting the contact 27, by briefly pressing the accelerator pedal 31, after which the vehicle can be allowed to increase in speed if the driver so desires without gearing up in order to maintain high engine braking power.

In the shift point diagram in Figure 2, only single-stage gears are plotted, but the invention can of course be applied with the same logical structure to multi-stage gears, where one or more gears are skipped depending on whether the acceleration on the vehicle, engine or accelerator indicates some or few gears must be skipped to meet the speed ratios that the acceleration value indicates are rapidly being achieved, and which would otherwise mean that the next gear would only be engaged to be quickly pulled out for further shifting.

Normally, it is the engine speed that determines the shift point so that upshift and nerve shifting take place at the same speed for all gears. The gears shown in Figure 2 mean that the speed value on the PTO shaft, between the 9th, 10th, 11th and 12th gears, is approximately at the following PTO shaft CRPM; 10 15 20 25 30 502 151 12 Normal Brake% increase Rpm diff Gear ratio G9 -> G10 780 rpm 1150 rpm 47% +370 rpm G10 -> G11 950 rpm 1420 rpm 49% +470 rpm G11 -> G12 1200 rpm 1770 rpm 47 % +570 rpm Nerve gear G10 -> G9 650 rpm 980 rpm 52% + 34O rpm G11 -> G10 800 rpm 1200 rpm 50% +400 rpm G12 -> G11 1000 rpm 1510 rpm 51% +510 rpm The above values show that the braking program's increase of the sávál as well as the nerve axis points entails a significant increase in the PTO shaft ratio.

For the engine speed ERPM applies; Normal Brake% increase Rpm diff Upshift G9 -> G10 1500 rpm 2200 rpm> 46% +700 rpm G10 -> G11 --- ~ --- - "" - --- ~ --- ---'- --- G11 -> G12 - "" - - "" - - "" - - "" - Nerváxling G10 -> G9 løoo rpm 1500 rpm so 96 + 5oo rpm G11 -> G10 - - "" - - "" - - "" - - "" - Giz -> G11 --'----- - "" - - "---- - "" - The upshift points for the engine speed are increased by just over 46%, but the increase of the upshift points should be in the range of 40-60%.

The nerve exchange points are increased by 50%, but the increase in the nerve exchange points should be in the range of 40-60%.

Claims (8)

10 15 20 25 30 35 502151 13 Patent claims 1. A method for influencing downshifting and shifting points in automatic transmission systems in motor vehicle gearboxes, which motor vehicles comprise means operable by the driver for activating the vehicle's braking equipment and where the downshifting and shifting points on released accelerator pedals are determined according to logical rules at primarily rated speeds k It is noted that during the driver's manual actuation of the means for activating the vehicle's braking equipment, there is an effect of downshifting and shifting points, whereby - when manually activating and maintaining manual activation of the means for the vehicle's braking equipment, both lowering and shifting points are raised from where primarily , - when manual activation of the device for the vehicle's braking equipment is released, the nerve change points are lowered to a lower speed, but the gear points are maintained at a higher speed, - upon subsequent activation of the vehicle accelerator pedal, the down and gear points are restored to the primary _ rvtalen Method according to claim 1, characterized in that when the manual actuation of the device for the vehicle's braking equipment is released, the nerve exchange points are lowered to a lower speed corresponding to the primarily set speed. 3. A method according to claim 2, characterized in that upon release of the manual activation of the device for the vehicle's braking equipment, the gear points are maintained at the primarily set speeds. 4. A method according to claim 1, 2 or 3, characterized in that the means for activating the vehicle's braking equipment is constituted by a means separate from a second actuating means for the ordinary wheel brakes of the vehicle, which means by its action activates an engine braking program which does not utilize the vehicle's wheel brakes, which wheel brakes preferably consist of conventional friction brakes acting individually against the respective wheels of the vehicle, and that the activated engine braking program by raising the nerve exchange points obtains a higher engine braking power from the engine. Method according to claim 1, 2 or 3, that while maintaining manual activation of the means for the vehicle's characteristics of braking equipment, an exhaust brake placed in the engine's exhaust system is also activated, which exhaust brake closes during this activation and thus gives increased engine braking effect. Method according to Claim 1, 2, 3 or 4, characterized in that the increase of the upshift point, ERPM, is to be in the range 40-60% and preferably just over 46%. A method according to claim 1, 2, 3 or 4, characterized in that the increase of the nerve exchange point is to be in the range 40-60% and preferably 50%. Device for actuating lowering and shifting points in automatic transmission systems for gearboxes (42) arranged between a motor (40) and drive shafts (43) coupled to the drive wheels (44) in motor vehicles, where the gearing system engages gears by means of servo devices (37) according to a program stored in the control unit of the shift system (12), which motor vehicle comprises an accelerator pedal (31) for actuating the engine, a regular service brake pedal (29) for activating at least the wheel brakes of the vehicle, and an additional auxiliary brake pedal ( 27) for activating auxiliary brakes in the vehicle such as retarder (48) and engine brake program (58) characterized in that the control unit (l2) comprises; - means (l2,5) for detecting that the accelerator pedal (3l) has been released at which state the down and upshift points through the stored program are assigned a first level (ND resp. NOW), means (12, l) for detecting if the auxiliary brake pedal (27) is activated and if the auxiliary brake pedal is kept activated, means (l2) for raising the lowering and shifting points from the first set level (ND, NU) to a second higher level (EBD, EBU) for both lowering and shifting points for respective gear as a function of activated auxiliary brake pedal (27), means (l2) for lowering the nerve shift points from the second higher level (EBD) to the first level (ND) as a function of released activation of the auxiliary brake pedal, means (l2) for reset the downshift and shift points from the second higher level (EBD, EBU) to the first level (ND, NU) as a function of the actuated accelerator pedal.