SE521517C2 - Gearbox for motor vehicles with an automatic clutch - Google Patents

Abstract

A transmission device in a motor vehicle, comprising an automated disk clutch (3) coupled to the output shaft (50) of an engine (1), a multi-stage gearbox (9) and a control unit for controlling the disk clutch and the engine. The control unit (45) is arranged so as, when input signals representing zero throttle are received, to give an output signal to disengage the disk clutch (3) and so as, when the throttle is subsequently opened, to give an output signal to engage the disk clutch (3) when the engine (1) has reached a rotation speed which may differ from the rotation speed of the input shaft (7) by at most a predetermined permitted speed difference.

Description

521 517 2 all when it comes to use in heavy vehicles, it is simpler and more robust and can be manufactured at a significantly lower cost than the traditional automatic gearbox and partly because it has a higher efficiency, which means the possibility of lower fuel consumption.

The planetary gearbox constructed by planetary gears usually has one-way clutches between the planetary gear stages, which when driving the engine in automatic transmission mode locks for torque transmission from the engine to the drive wheels but which when torque transmitting in the opposite direction, ie at zero throttle and the vehicle in motion, disengages and lets the vehicle which results in lower fuel consumption by utilizing the vehicle's kinetic energy than if the engine is at a standstill. The corresponding freewheel function of hitherto known automated step gearboxes has so far not been possible in any other way than by manual release of the coupling between the engine and the gearbox.

The object of the present invention is to provide a transmission comprising a gearbox and an automated disc clutch of the type indicated in the introduction, which is designed in such a way that an automatic freewheel function corresponding to that of the traditional automatic gearbox with planetary gears and freewheels can be obtained.

This is achieved according to the invention in that the control unit is arranged to give an output signal representing zero throttle to disengage the clutch and to give an output signal at a subsequent throttle to engage the clutch when the engine has reached a rotational speed, which may differ from said rotating speed. no more than a predetermined permissible speed difference.

By disengaging the clutch, the driveline is disengaged, so that the vehicle can roll freely without the braking effect otherwise obtained by the friction losses in the engine. In this way, freewheel function is thus achieved without the use of special freewheel clutches.

In a preferred embodiment of the transmission according to the invention, an automated vane coupling arranged between the vehicle engine and the stepped gearbox is used for the freewheel function and where the engine is equipped with an engine brake device of the exhaust pressure regulator or compression brake type.

The control unit is hereby arranged to disengage the automated disc clutch in the event of input signals representing zero throttle and the engine brake switched off.

In order to prevent a possible engine stop at the same time as the freewheel function is activated, as a result of different servos, eg steering and brake servos, ceasing to function by the servo pumps stopping at the same time as the engine, the control unit is arranged to receive of input signals which indicate that the engine is stopping and that a certain vehicle speed is present at the same time as said automated clutch (3) is disengaged give a signal to switch on the automated clutch (3). The engine idle speed is normally adapted to prevailing conditions such as temperature conditions.

This means that the indication of when the engine is stopping, ie a minimum permitted engine speed where freewheeling is permitted, varies. When the clutch connects the gearbox to the engine, the engine and the servo pumps connected to it are driven by the vehicle, so that the servo functions are maintained.

The invention is described in more detail with reference to exemplary embodiments shown in the accompanying drawings, in which Figure 1 shows a schematic representation of an internal combustion engine with connecting clutch and gearbox and Figure 2 the clutch and gearbox in Figure 1 on an enlarged scale.

In Figure 1, 1 denotes a six-cylinder internal combustion engine, for example a diesel engine, whose crankshaft 2 is coupled to a single-disc dry single-plate clutch generally designated 3, which is enclosed in a clutch housing 4. The crankshaft 2 is inextricably connected via the engine shaft 50 5, while its lamella disc 6 is inextricably connected to an input shaft 7, which is rotatably mounted in the housing 8 of a gearbox generally designated 9. In the housing 8, a main shaft 10 and an intermediate shaft 11 are also rotatably mounted.

As most clearly seen in Figure 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 rotatably connected to the input shaft. by means of the coupling sleeve 13, a gear 15 rotatably mounted on the main shaft 10 is also lockable relative to the input shaft 7. With the coupling sleeve 13 in a central position, both gears 12 and 15 are disengaged from their shafts 7 and 10, respectively. The gears 12 and 15 engage gears 16 and 16, respectively. 17, which are non-rotatably 521 517 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 rotatably mounted on the main shaft 10, the main shaft by means of coupling sleeves 24 resp. 25, 22 and 23, respectively, which are lockable on which in the 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 also together with the pair of gears 21, 18, 22, 19, 23, 20 and 28, form a reverse gear. At the output end of the main shaft, a gear base gearbox with four forward gears and wheels 31 is rotatably arranged, forming the sun gear in a planetary type gearbox designated 32, whose planet gear carrier 33 is rotatably connected to an axle shaft 34.

The planetary gear 35 of the range gear 32 engages with a ring gear 36, which by means of a clutch sleeve 37 is lockable relative to the gearbox housing 8 for low range LR and relative to the planet gear carrier 33 for high range HR.

The coupling sleeves 13, 24, 25, 26 and 37 are displaceable as shown by the arrows in Figure 2, whereby the gear steps shown in connection with the arrows are obtained.

The displacement is effected by means of diagrammatically actuated piston-cylinder devices of the type, indicated servos 40, 41, 42, schematically 43 and 44, in Figure 2, which may be used in a gearbox of a w ... à c ~ described above. : å w O \ slag, which is marketed under the name Geartronic®. 43 and 44 are controlled by a servo unit 40, 41, 42, electronic control unit 45 (see figure 1), comprising a microcomputer, depending on signals input into the control unit representing different engine and vehicle data, which at least include engine speed, vehicle speed, accelerator pedal position and, where applicable, engine braking off, when an electronic gear selector 46 connected to the control unit 45 is in its automatic gear position. When the selector is in the manual shift position, the change is made at the driver's command via the gear selector 46.

The control unit 45 also controls the fuel injection, ie the engine speed, depending on the accelerator pedal position and the air supply to a pneumatic piston-cylinder device 47, by means of which the vane coupling 3 is disengaged or engaged.

According to the invention, the control unit 45 is programmed so that the freewheel function is activated when the driver or cruise control no longer requests any fuel (zero throttle) or activation of any engine brake, for example an exhaust pressure regulator or a compression brake.

This is done so that the control unit 45 first controls the engine speed, so that no torque is transmitted between the output shaft 50 of the engine 1 and the input shaft 7 of the gearbox 9. Thereafter, the control unit 45 signals the cylinder device 47 to disengage the disc clutch 3, after which the motor 1 is controlled at idle speed.

The driveline is now disconnected and the vehicle can roll freely. By disengaging the disc clutch, the freewheel function is achieved regardless of which gear is engaged in the base gearbox.

The control unit 45 is programmed to deactivate the freewheel function when the driver requests fuel with the accelerator pedal or cruise control or requests engine braking by, for example, activating an exhaust brake or compression brake. In this case, the control unit first adjusts the engine speed to a speed that does not differ too much from the rotational speed of the input shaft before the lamella clutch is engaged. The driveline is now connected and drive or engine braking is possible. If the difference in speed when engaged becomes too great between the output shaft of the engine and the input shaft of the gearbox, the vehicle jerks. This is not acceptable in terms of comfort. In addition, the slats in the coupling 3 wear abnormally. Other parts of the transmission are also exposed to higher stresses than normal.

In the control unit 45 a safety function is also programmed, should the engine stop when the freewheel function is activated. The safety function means that the control unit 45 gives a signal to reconnect the disc clutch 3 if the engine stops during freewheeling. When the disc clutch 3 is engaged, the engine is powered by the vehicle's kinetic energy and any attachments such as servo pumps and engine brakes, which are normally powered by the engine, are now powered by the vehicle via ITlOtOITi. It is also possible to use other types of automated couplings between engine and gearbox than said lamella coupling in the device according to the invention.

Claims (1)

521 517 'Patent claim A transmission device for motor vehicles, comprising a stepped gearbox (9) with an input shaft (7) rotatably mounted in a housing (8), at least one intermediate shaft (11) mounted in the housing, which has at least one gear ( 16, 18) engaging a gear (12, 15) on the input shaft, a main shaft (10) mounted in the housing with gears (15, 21, 22, 23) engaging gears (18, 19, 20) on the intermediate shaft, wherein 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 with coupling means (13, 24, 25) is lockable on its shaft, and where the input shaft (7) is connected to an automated clutch (3), which is connected to a shaft (50) emanating from an engine (1) and which is controlled by a control unit (45) in dependence on signals input into the control unit representing different engine and vehicle data which includes at least engine speed, vehicle speed and accelerator pedal position, characterized in that the control unit n (45) is arranged to give an output signal representing zero throttle to input the clutch (3) and in a subsequent throttle to output the clutch (3) when the engine (1) has reached a rotational speed, which may differ from said input axis (7) rotational speed with not more than a predetermined permissible speed difference. Transmission device according to Claim 1, coupled to an engine with engine braking means for increasing the engine braking power, characterized in that the control unit (45) is arranged to provide an output signal in the case of inputs representing zero throttle and the engine braking means switched off. Transmission device according to any one of claims 1 or 2, characterized in that the control unit is arranged that upon receipt of input signals which indicate that the engine is stopping and that a certain vehicle speed is present at the same time as said automated clutch (3) is disengaged to signal the automated clutch (3). Transmission device according to one of the preceding claims, characterized in that the operating means (40, 41, 42) cooperate with the coupling means (13, 24, 25), which operating means are controlled by said control unit (45). Transmission device according to one of the preceding claims, characterized in that the coupling (3) is of the lamella coupling type.