SE525105C2 - Power units for motor vehicles - Google Patents

Abstract

Drive means for motor vehicles, comprising an internal combustion engine (1) and an unsynchronised automated stepped gearbox (9). The clutch and the gearbox are controlled by an electronic transmission control unit (45), which communicates with an engine control unit (48), to which are fed signals representing the selected gear from a gear selector (46) and signals representing various engine and vehicle data. The input shaft (7) to the gearbox is coordinated with a torque sensor (60), which sends a signal corresponding to the input shaft torque to the transmission control unit, which is disposed to initiate shifting only when the torque sensor indicates that the torque on the input shaft is zero or at least practically zero.

Description

-25 105 2-speed continuously variable base gearbox and a range gearbox contribute to the absence of synchronizations to further reduce the cost. The absence of synchronizing means makes it possible to make the gearbox shorter or alternatively to make the gears wider with a given length than in a synchronized gearbox with a corresponding length in order thereby enabling the transmission of higher torques.

In general, at least three control parameters, namely the engine speed, the torque on the input shaft of the gearbox and the vehicle speed, determine when shifting should take place according to a shifting strategy stored in an engine and transmission control computer. The torque on the input shaft of the gearbox is here equated with the engine torque, ie the load on the engine, which is obtained from the sensor indicating the amount of fuel delivered to the engine, for example a speedometer or sensor indicating accelerator pedal position. When initiating the gear unit, ie disengaging the existing gear unit, the torque transmission between the engine and the gearbox must be as small as possible. Ideally, the driveline should be torque-free in order to achieve a complete jerk fi in disengagement. In the control computer, values are programmed on how large the amount of fuel delivered shall be for different gear points in order for the torque on the input shaft of the gearbox to be close to zero or in any case so low that the existing gear can be disengaged without troublesome jerks. After disassembly of the gear, the control computer controls the engine speed for synchronization with the speed of the gear to be engaged. When the speeds have been synchronized, the new gear is engaged.

With the known method of estimating the torque equal to zero or close to zero between the engine and the gearbox, no feedback takes place. Because the level is tuned so that it is correct for any car, it is not certain that it is true for all cars. In addition, the motor torque varies depending on the motor internal loss losses, which are temperature dependent. If attachments such as a power take-off, compressed air compressor, cooling fl genuine and or AC compressor are connected, the motor torque signal will indicate torque transmission even when the torque transmission between the engine and the gearbox is equal to zero. Varying fuel quality (with varying energy content) will also affect the possibilities of controlling the driveline to a mentless state. The levels of torque to the attachments must also be estimated and stored in the control computer and the engine control must take into account whether one or fl your attachments are switched on or off.

An object of the present invention is to provide a drive unit of the type stated in the introduction, in which it is possible to always determine exactly torque-free condition in the vehicle's driveline so that when changing, regardless of variations in the engine's own inertia, which depends on variations in the engine temperature, and regardless of whether any or one or more of your attachments are connected, enable jerk-free disengagement of the variable gear without disengaging the driveline clutch.

A further object of the present invention is to provide such a drive unit, in which it is possible to control the engine speed reduction resp. increase with great precision to achieve fast, accurate and jerk-free gears.

This is achieved according to the invention in that the input shaft of the gearbox is coordinated with a torque sensor, which gives a signal depending on the torque on the input shaft to said control means, that a sensor is arranged, which gives a signal to the control means indicating the attachment is switched on or off and that the control means are arranged to initiate shifting when switching to an unsynchronized gear first, when the torque sensor indicates that the torque on the input shaft is zero or at least in the nearest zero By using a torque sensor feedback of the torque and torque is obtained - the driveline can be controlled to zero regardless of the inertia of the motor temperature varying inertia and independent of the operating condition of any attachments.

According to a preferred embodiment of the drive unit according to the invention, the control means are arranged to register the amount of fuel delivered at the input gear moment equal to zero or in the nearest zero and during speed adjustment during the gearing process control the engine with regard to the engine torque corresponding to the registered fuel quantity.

By starting from the registered engine load during the speed control of the motor during the shift process, when the engine speed is to be adapted to the next gear, a faster and more precise control can be achieved.

The invention is described in more detail with reference to exemplary embodiments shown in the accompanying drawings, where ñg. 1 shows a schematic representation of an embodiment of a drive unit according to the invention, fig. 2 the clutch and the gearbox in fi g. 1 on an enlarged scale and fi g. 3 is a diagram of engine torque and gearbox torque as a function of shifting time.

I fi g. 1, 1 denotes a six-cylinder internal combustion engine, for example a diesel engine, the crankshaft 2 of which is coupled to a single-disc dry single-clutch clutch generally designated 3, which is enclosed in a clutch housing 4. Instead of a single-disc disc clutch, a two-disc clutch can be used. The crankshaft 2 is non-rotatably connected to the coupling housing 5 of the clutch 3, while its lamella disc 6 is non-rotatably connected to an input shaft 7 (fi g. 2), which is rotatably mounted in the housing 8 of a gearbox generally designated 9. In the housing 8, a main shaft 10 (fi g. 2) and an intermediate shaft 11 (fi g. 2) are rotatably mounted.

As most clearly shown by fi g. 2, a gear 12 is rotatably mounted on the input shaft 7 and lockable on the shaft by means of a coupling sleeve 13 provided with synchronizing means, which is rotatably but axially displaceably mounted on a hub 14 inextricably connected to the input shaft. By means of the coupling sleeve 13 also a gear 15 rotatably mounted on the main shaft 10 lockably relative to the input shaft 7. The gears 12 and 15 engage with gears 16 and 16, respectively. 17, which are non-rotatably connected to the intermediate shaft 11. On the intermediate shaft 11, further gears 18, 19 and 20 are rotatably arranged, which engage with gears 21, 22 and 22, respectively, rotatably mounted on the main shaft 10. 23, which are lockable on the main shaft by means of coupling sleeves 24 resp. 25, which in the exemplary embodiment shown do not have synchronizing devices. On the main shaft 10, a further gear 28 is rotatably mounted and engages with an intermediate gear 30 rotatably mounted on a separate shaft 29, which in turn engages with the intermediate shaft gear 20. The gear 28 is lockable on its shaft by means of a coupling sleeve 26.

The gear pairs 12, 16 and 15, 17 and the clutch sleeve 13 form a split gear with a low gear stage LS and a high gear stage HS. The pair of gears 15, 17 together with the pair of gears 21, 18, 22, 19, 23, 20 and 28, 30 also form a basic gearbox with four forward gears and a reverse gear. At the output end of the main shaft 10, a gear 31 is rotatably arranged, which forms the sun gear in a planetary type two-speed gearbox designated 32, whose planet gear carrier 33 is rotatably connected to a shaft 34 which forms the output shaft of the gearbox. The planetary gear 35 of the range gear 32 engages with a ring gear 36, which by means of a coupling sleeve 37 is lockable relative to the gearbox housing 8 for low-range LR and relative to the planetary gear carrier 33 for high-range HR. The coupling sleeve 37 also has a neutral position NR lying between the gear positions LR and HR, in which the output shaft 34 is disengaged from the main shaft 10.

The coupling sleeves 13, 24, 25, 26 and 37 are displaceable as the arrows show in fi g. 2, whereby the gear steps shown in connection with the arrows are obtained. The displacement is effected in fi g. 2 schematically indicated servos 40, 41, 42, 43 and 44, which may be pneumatically actuated piston-cylinder devices of the type used in a gearbox of the type described above, which is marketed under the name Geartronic®. The servo unit is controlled by an electronic transmission control unit 45 (fi g. 1), comprising a microcomputer, depending on signals input into the control unit representing different engine and vehicle data, which includes at least engine speed, vehicle speed, clutch and accelerator pedal position and, where applicable, engine brake on-off, when an electronic gear selector 46 connected to the control unit 45 is in its automatic position.

When the selector is in the position for manual shifting, the shifting takes place at the driver's command via the shift selector 46. The transmission control unit 45 communicates with an engine control unit 48 and together with this also controls the fuel injection, ie the engine speed, depending of the accelerator pedal position and the air supply to a pneumatic piston-cylinder device 47, by means of which the coupling 3 is engaged and disengaged.

The transmission control unit 45 is programmed in a known manner so that it keeps the clutch 3 engaged when the vehicle is stationary and the gear selector 46 is in the neutral position.

This means that the motor drives the input shaft 7 and thus also the intermediate shaft, while the output shaft 34 is disengaged. Any attachments driven by the intermediate shaft, such as an oil pump for gearbox lubrication, are operated in this position. The control unit 45 is further programmed to, when the vehicle is stationary and the gear selector fl is moved from the neutral position to a gear position, either to a position for automatic transmission or to a position with the starting gear selected by the driver, first disengage the clutch 3, then brake the intermediate shaft 11 to stop using it in fi g. 2, which may be a per se known brake device controlled by the control unit 45.

With the intermediate shaft 11 braked to a stop or in any case at least almost to a stop, the control unit 45 now initiates shifting in the base gearbox to a starting gear, which is given by the automatic or by the driver selected total gear. When the driver after acceleration of the selected starting gear, eg one gear, gives gas, the accelerator pedal functions as a reverse clutch pedal, which via the transmission control unit gradually increases the clutch engagement with increasing throttle.

When shifting - initiated either directly by the driver or by the automatic depending on a gear selection strategy stored in the transmission control unit 45, which can take into account what the vehicle's environment looks like a bit into the future - the transmission control unit 45 first controls the engine control unit 48 to regulate fuel supply to the engine. that torque-free or almost torque-free condition is created in the vehicle's driveline, ie the torque transmission from the engine 1 crankshaft 2 to the input shaft 7 of the gearbox 9 must be zero or at least almost zero. The transmission control unit 45 receives continuous information about and registers the current engine torque via injected fuel quantity and the current torque on the input shaft 7 via a torque meter 60 coordinated with the shaft, which may be of an in-between known, hitherto used in laboratory contexts type. The torque can, for example, be calculated on the basis of measured torsion in the shaft 7. If the torque is registered equal to zero or almost zero on the input shaft 7, the current gear is switched off.

Based on the registered amount of fuel, which indicates the current engine load at this time, the transmission control unit 45 controls the engine control unit 48 to regulate the amount of fuel to the motor for speed synchronization with the gearbox speed for the new gear, after which the new gear is engaged. attachment, which may be a motor / motor-mounted power take-off, which may be engaged or disconnected by means of a control 62 operated by the driver control unit 48 connected to the engine control unit 48. If one or more of the attachments 61 are connected via the driver-operated control 62, the engine load larger and larger amount of fuel is required for the synchronization than if no additive is connected.

By registering and starting from the actual engine load at torque-free driveline, a fast and jerk-free shift can be achieved.

The transmission control unit 45 is also arranged to, when driving, when shifting does not take place, register which attachment unit (s) 61 are connected (in whole or in part), together with the difference between the motor torque and the torque on the input shaft of the gearbox. A number of different combinations are registered. The control unit 45 is in this case arranged to calculate the load of the respective attachment unit on the motor.

I fi g. 3 shows the control in connection with shifting in the gearbox where curve “a” illustrates the motor torque at torque deduction in connection with shifting and connected attachment 61, while curve “b” illustrates the torque on the gearbox input shaft 7 during the same period. As can be seen from the fi gear, the motor torque never coincides with the torque on the input shaft 7, as one torque must be maintained to drive the attachment (s). As can also be seen from the 10 clock 10 525 1os 8, the input shaft 7 becomes torque-free only some time after the motor torque has reached its minimum.

The transmission control unit 45 is arranged to register the internal friction of the engine as a function of the engine temperature even when driving, when shifting does not take place by registering the difference between the engine torque and the torque on the input shaft of the gearbox.

The transmission control unit 45 is also arranged to control the engine control unit 48 to compensate for variations in the internal friction of the engine caused by temperature variations when controlling the fuel supply to the engine during the shifting process, guided by the engine torque, the torque on the input shaft 7 and the engine temperature.

Claims (6)

10 15 20 25 525 105 9 Patent claims Propulsion unit for motor vehicles, comprising an internal combustion engine (1) with at least one attachment unit (61), which is drivably coupled to a power take-off on the engine, and an input shaft (7) connected via a vane coupling (3) to the engine crankshaft (2) to a stepped gearbox (9) having at least one intermediate shaft (11) mounted in a housing, which has at least one gear (16, 17) engaged with a gear (12, 15) on the input shaft, a main housing (10) mounted in the housing with gears (15,2l, 22,23) engaging gears (17,18, 19,20) on the intermediate shaft, the at least one gear in each pair of interlocking gears on the intermediate shaft and the main shaft is rotatably mounted on its shaft and lockable by means of coupling means (13,24,25), of which at least the coupling means for some forward gears have no synchronizing function, and actuating means (40,4l, 42) cooperating with the coupling means, which are controlled by control means (45, 48) connected to a gear selector (46) with transmission control function and engine control function, in which signals representing the selected gear are input as well as various engine and vehicle data, which at least include engine speed, speed of the gearbox input shaft and vehicle speed, characterized in that the gearbox input shaft (7) is coordinated with a torque sensor (60), which gives a signal depending on the torque on the input shaft to said control means (45, 48), that a sensor (62) is provided, which gives a signal to the control means indicating whether the attachment is switched on or off. and that the control means are arranged to initiate shifting when switching to an unsynchronized gear only when the torque sensor indicates that the torque on the input shaft is zero or at least in the nearest zero Drive unit according to claim 1, characterized in that the control means (45, 48) are coordinated with sensors which give a signal to the control means, which represents the amount of fuel delivered to the engine. - Q n ø a ø a »o Drive unit according to Claim 2, characterized in that the control means (45, 48) are arranged to register the amount of fuel delivered at the input torque equal to zero or close to zero and to control the engine (1) with respect to the speed adjustment during the shift process. to the engine torque corresponding to the registered amount of fuel. Drive unit according to one of Claims 1 to 3, characterized in that the control means (45, 48) are arranged to compensate the torque on the input shaft (7) of the gearbox and the engine temperature when controlling the motor (1) during the shifting process guided by the motor torque. for variations in the internal friction of the motor caused by temperature variations. Drive unit according to one of Claims 1 to 4, characterized in that the control means (45, 48) are arranged to register the internal friction of the motor as a function of the motor temperature when driving by registering the difference between the motor torque and the torque on the input shaft (7). Drive unit according to any one of claims 1-5, characterized in that said control means (45, 48) comprise a transmission control unit (45) and a motor control unit (48) which communicate with each other.