GB2245036A

GB2245036A - Clutch plate speed determining apparatus used in a power line to drive a vehicle

Info

Publication number: GB2245036A
Application number: GB9114305A
Authority: GB
Inventors: Roger Porter Jarvis
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1988-04-30
Filing date: 1991-07-02
Publication date: 1991-12-18
Anticipated expiration: 2011-07-02
Also published as: US5072815A; GB9114305D0; GB2233053B; GB8810365D0; GB9017505D0; GB2233053A; DE68918707D1; KR900700318A; EP0448551B1; GB2245036B; EP0448551A1; WO1989010282A1; KR960016557B1; JPH03503870A; DE68918707T2

Abstract

The present invention provides apparatus for determining the speed of rotation of a clutch driven plate (32), the apparatus comprising a first sensor for sensing the speed of rotation of a gearbox output shaft, a second sensor (61) for sensing which gear ratio in a gearbox (10) is engaged and control means (40) for receiving signals from said sensors and calculating the clutch driven plate speed. <IMAGE>

Description

POWER LINE TO DRIVE A VEHICLE The present invention concerns a power line to drive a vehicle. In such a power line, in order for clutch control to be provided, at least partially, by an electronic control, various parameters of the power line have to be monitored. It is an ail of the present invention to provide a convenient way of providing signals to a control unit which are indicative of Clutch Division plate speed The present invention provides apparatus Cor determining the speed oE rotation of a clutch driven plate, the appartus comprising a first sensor for sensing the speed of rotation of a gearbox output shaft, a second sensor for sensing which gear in a gearbox is engaged and control means or receiving signals from said sensors and calculating the clutch driven plate speed.

The present invention also provides a power line, to drive at least one ground running wheel of a motor vehicle, said power line comprising an internal combustion engine giving a rotary motion output, fuel supply means to supply fuel to said engine, said fuel supply means conlprising controllable throttle means openable and closeable to vary the amount that the throttle means is open to increase and decrease supply of fuel to the engine, a change speed gearbox having a rotary output shaft for supplying rotary motion to said ground running wheel and a rotary input shaft for receiving output torque from the engine and a plurality of gear ratios between shafts, each gear ratio being engageable and disengable in response to operation of gear ratio selector means in response to manual action of a driver oE the vehicle, a clutch interposed between said engine and said input shaft for transmitting engine output torque to the input shaft, clutch control means operable to vary the torque transmitting capacity of said clutch over a range from a pre-determined maximum capacity (clutch fully engaged) to substantially zero capacity (clutch fully disengaged), the clutch control means being responsive to occurence of a first signal indicative of a wish by the driver to disengage the currently engaged said gear ratio and being responsive to occurence of a second signal indicative that another said gear ratio has been engaged, said clutch control means responding to said first signal to cause the clutch automatically to disengage substantially fully and responding to said second signal to cause the clutch automatically to engage substantially fully, throttle control means to open and close said throttle means in response to driver initiated throttle demand signals, said control means being arranged to receive signals, said control means being arranged to receive signals from a driven plate speed determining gleans which comprises a gearbox output shaft speed sensor and a gearbox condition sensor.

The invention will now b0 further described, by way of example, with reference to the accompanying drawings in which: Fig. 1 diagrammatically represents a motor vehicle provided with a power line formed according to the invention; Fig. 2 diagrammatically illustrates the power line used in Fig. 1; Fig. 3 is a set of graphs illustrating operation of elements in the power line in Fig. 2 in the course of a gear change from a lower gear ratio to a higher ratio; Fig. 4 diagrammatically represents a fuel injection system which may be substituted for the carburettor in Fig.

2, and; Fig 5 diagrammatically represents a diesel engine which may be used in the power line in Fig. 2 instead of the petrol engine, the throttle means being a rack controlled diesel fuel detering valve system.

Fig 1 shows a motor vehicle 2 having front and rear road wheels 4 and 6, an internal combustion engine 8 and a change-speed gearbox 10 having a rotary output shaft 12 (Fig. 2) from which drive is taken in this example to drive the front wheels 4 but could be taken to drive the rear wheels instead of or in addition to the front wheels.

Referring now to Figs 1 and 2, the change speed gearbox 18 has a rotary input shaft 14, and between the input and output shafts, a plurality of forward gear ratios known per se each respectively engaged, or disengaged, in response to manual operation by the vehicle's driver of a gear ratio selector device 16, in this example in the form of a gear lever, front which signals, in this example in the form of movement, are transmitted via a connection or linkage 18 to gear ratio change means in the gearbox. On the other hand any form of manually actuable gear selector device may be used from which gear ratio disengage and engage signals can be transmitted to gear ratio change means in the gearbox 18.

Driving torque is input to the gearbox l through the input shaft 14 driven via a friction clutch 2G, in a housing 22, by the engine 8. In this example the clutch O is a push - type diaphragm spring clutch known oer se having a cover 24 secured to a fly-wheel or other counter-pressure plate 26 rotated by the engine. The clutch 2(3 includes a pressure plate 28 acted on by diaphragm spring 3(3 and driven plate 32 with an internally splined central huh engaging splines on the input shaft 14. The clutch also has a release bearing 34 acted on by a release fork or lever 36 pivotably supported at 38 and pivoted at 4 to a thrust rod 42 of a piston 43 of a hydraulic actuator 44.The position of the piston 43 is controlled by the amount of hydraulic fluid in the actuator 44 and that amount of fluid is controlled by hydraulic control 46. Operation of the hydraulic control 46 is under control of an electronic control 48 comprising computer means connected by signal path 5(3 to the hydraulic control and by signal path 52 to a position sensor 54. Sensor 54 observes the position of the piston 43 in actuator 44. The position of piston 43 is correlated to the position of the pressure plate 28 relative to the counter-pressure plate 26, which relative position of the pressure plate 28 is a function of the torque transmitting capacity of the clutch 20, namely the maximum torque that the clutch can transmit at any instant to the input shaft 14 from the engine before occurence of clutch slip.The torque transmitting capacity is a function of the force exerted on the pressure plate 28 by the diaphragm spring 30 which in turn is a function of the position of the release bearing 34 and thus a function of the position of piston 43. In one extreme position of travel of the piston 43 the diaphragm spring 30 exerts maximum force on the pressure plate 28 and thus the torque transmitting capacity is a pre-determined maximum, hence the clutch 20 is fully engaged. In another extreme position of the piston 43 the diaphragm spring 30 exerts no pressure on the pressure plate 28 and thus the torque transmitting capacity is zero, hence the clutch is fully disengaged.

Therefore depending on the position of piston 43 the torque transmitting capacity can be varied over the range from zero to said pre-determined maximum.

The electronic control 48 can signal the hydraulic control 46 to provide an amount of hydraulic fluid in the actuator 44 consistent with a desired torque transmitting capacity for the clutch 20, and the sensor 54 provides the electronic control with signals indicating the position of the piston 43 so that the electronic control knows when the desired piston position has been attained.

Speed sensors 56 and 58 are provided to send to the electronic control 48 signals indicative of the speed of the engine 8 and the speed of the input shaft 14 respectively. Alternatively, in place of the sensor 58 another sensor may b used to observe the speed of the output shaft 12 and send signals to the electronic control 48. The electronic control 48 can then automatically calculate the speed of the input shaft 14 using the observed speed of the shaft 12 and the ratio of the engaged gear in the gearbox 10, because the system can be arranged so that electronic control always knows which gear ratio is currently engaged and thus which ratio to use in the calculations.

Electronic control 48 is also connected by two signal paths 60 and 62 to the gearbox 10 and the gear lever 16 respectively. The information in the signal on line 60 from gearbox condition sensor 61 indicates when a gear ratio is engaged and when no gear ratio is engaged. As a consequence the electronic control 48 observes, when a new gear ratio is engaged, if the engaged new ratio is higher than the immediately previously engaged ratio (namely that the gear change is an up-shift). In the arrangement shown in Fig.2 the electronic control 48 does this by "seeing" that the speed of the input shaft 14 has dropped significantly below the speed of the engine 8.Information in the signal on line 62 indicates when the driver desires or does not desire to change gear. Gear lever 16 comprises a shaft 64 arranged to pivot universally at 66.A tube 68 surmounted by hand knob 70 is pivotably mounted at 72 on the shaft 64 so that the tube can wobble or rock slightly relatively to the shaft. Such wobbles caused by the driver grasping the knob 70 causes switch or transducer means 74 to initiate a signal on line 62 indicating the driver's wish to change gear. In response the controls 48 and 46 automatically function causing the clutch 20 automatically to disengage fully. Further manual movement of the knob 70 causes the shaft 64 to move to cause operation of the gear ratio change means to cause disengagement of the hitherto engaged gear ratio and the engagement of another gear ratio. That engagement produces a signal on line 60 causing controls 48 and 46 automatically to function so that the clutch 20 is re-engaged automatically.In the case of an up-shift the manner of the clutch re-engagement will be described in more detail below.

Engine 8 in Fig. 2 is a petrol engine having a fuel supply system cornprising a carburettor 76 comprising air-filter 78, induction pipe 80, fuel jet 82 and a pivotting butterfly or flap valve 84. In this example 100% or full throttle is when the valve 84 is pivotted to the position providing least obstruction to air-flow along the pipe 80 permitted by the design of the carburettor, and 0% or zero throttle is when the valve 84 is in the position providing most obstruction permitted by the carburettor design to air-flow along the pipe 80.

The vehicle has a driver operated accelerator or throttle demand pedal 86 which is pivotably movable by the driver to any desired position in a range of permitted movement. One end of the range corresponds to 0% throttle and the other end corresponds to 100% throttle, thus the pedal can be moved in the range to any position corresponding to the percentage throttle the driver desires to demand. So the pedal position at any instant represents a throttle demand signal, and a pedal position sensor 88 provides on signal path 90 signals which are sent to the electronic control 48 and represent the amount of throttle currently being demanded by the driver.

The extent to which the valve 84 is opened can be controlled by motor means 92, for example an electric motor, driving a mechanical connection 94 acting on the valve 84 which has a throttle or valve position sensor 96 sending signals indicative of the valve position on signal path 98 to the electronic control 48.

Accordingly, when the electronic control 48 receives a throttle demand signal on path 90 the electronic control automatically sends a signal on path 100 causing the motor means 92 to move the valve 84 to the position providing the desired percentage throttle. The attainment of that position is confirmed to the electronic control 48 by signals from the sensor 96.

The operation of a vehicle provided with the power line described with reference to Fig. 2 will now be described with reference to Fig. 3 over a time period from initiation to completion of an up-shift. In Fig. 3 there are three sets I, II and III of orthogonal axes in which abscissae t represent time, are of the same scale, and commence at the same zero point 0. In set I the ordinate S is speed in revolutions per minute (r.p.m), curve A representing variation in the speed of the engine 8, and curve B representing variation in the speed of the input shaft 14 (and clutch driven plate 32). In set II the ordinate C represents the torque transmitting capacity of the clutch 20, C1 being the pre-determined maximum capacity. Ordinate % T in set III represents percentage throttle.

During the time period from initiation to completion of the up-shift the clutch and throttle are under the control of the electronic control 48 (Fig. 2) operating in accordance with a computer program.

At time tl the driver wobbles the knob 70 (Fig. 2) signifying an intention to change gear.

Accordingly the controls 48 and 46 act to increase the amount of hydraulic fluid in the actuator 44 resulting in the torque transmitting capacity C of the clutch 20 ramping down rapidly at a pre-determined rate (represented by graph section 102) to zero transmitting capacity. It should be noted that at time t the driver is demanding Td % throttle, but because electronic control 48 understands that a gear change is taking place control 48 takes full control of the throttle even though the driver may hold pedal 86 steady to continue to demand Td % throttle throughout the gear change. At tl the control 48 acts on motor means 92 causing the valve 84 to close at a pre-determined rate illustrated by graph section 104. Because the disengaging clutch (section 102) reduces the load on the engine the engine speed increases initially (graph section 106), but only slightly because simultaneously the throttle is closing (graph section 104). Also the rate of increase in the speed of the clutch driven plate 32 decreases (graph section 108) since the free-wheeling vehicle now begins to drive the gearbox 10 and input shaft 14. After initially closing the throttle at a pre-determined rate (graph section 104) the electronic control 48 holds the throttle open at Tic8, Tc being a value calculated by control 48 and being a function of the speed of the clutch driven plate, observed by sensor 58.

As the driver continues the gear change by still pushing on the knob 70 to move the shaft 64, synchroniser cones associated with the desired new gear ratio engage at time t2 having the effect of rapidly decelerating the driven plate (graph section 110) down to speed Sn which is the speed at which the momentum of the vehicle is driving the input shaft 14 via the gearbox. Because the control 48 senses the decrease (graph section 110) in clutch driven plate speed, the control again acts on the motor means 92 to close the throttle at a pre-determined rate (graph section 112) from Tc% to 0%. Because the throttle is closed further at time t2 the speed of the engine 8 starts to slow (graph section 114) under the effect of zero throttle. The drop in speed of the clutch driven plate 32 between times t2 and t3 is sufficient for the control 48 to detect that an up-shift is taking place.

Between times t3 and t4 the synchroniser sleeve associated with the new ratio becomes engaged. Thus at time t4 the sensor 61 signals control 48 that a gear ratio has been engaged. Because it is an up-shift the electronic control 48 responds by continuing to maintain the throttle at 0% (graph section 116) and operates the hydraulic clutch control 46 to reduce the amount of fluid in the hydraulic actuator 44 at time t4 so that the torque transmitting capacity C of the clutch 20 starts to increase at a pre-determined relatively fast rate (graph section 118) up to a target torque transmitting capacity Ct.The value Ct in calculated by the electronic control 48 and is a function of substantially the current engine speed and substantially the current amount of throttle demanded by the driver at pedal 86, Ct being calculated to be substantially equal to the engine torque output which would be delivered at that engine speed if the percentage throttle were equal to that being demanded by the driver.

As the clutch 20 is engaged, the pressure plate 28 moves closer to the counter-pressure plate 26 until a kiss point is reached at time t5 where the driven plate 32 is so pressed against the counter-pressure plate that load of the vehicle a now effectively applied to the engine 8 and the engine speed reduces more rapidly (graph section 120). This is because the clutch 20 is acting as an engine brake. Because the vehicle is so heavy its momentum is little influenced and thus the speed of the clutch driven plate remains substantially constant at Sn (graph section 122).

After attainment of the target torque transmitting capacity Ct at time t6, the electronic control 48 continues to cause the hydraulic control 46 to reduce the amount of fluid in the actuator 44 so that the torque transmitting capacity of the clutch 20 continues to increase (graph section 124) but at a pre-determined lower rate until at time t9 the torque transmitting capacity of the clutch is restored to its pre-determined maximum value C1.

A pre-determined time period tx commences to be counted out in the electronic control 48 when the gear ratio engaged signal appears at time t4. The expiry of the period tx occurs at time t7 whilst the clutch is still being returned to its maximum transmitting capacity C1. Over the period between t6 and t7 the torque transmitting capacity of the clutch 20 continues to increase and thus the braking effect of the clutch on the engine 8 continues as illustrated at graph portion 126 in which the rate of reduction of engine speed or deceleration is shown increasing.When the time period tx is counted out at t7 the electronic control 48 instructs the motor means 92 to open the valve 84 so that the amount the throttle is open increases at a pre-determined rate (graph section 128) until at time t8 the throttle reaches Td% which is equal to that currently being demanded by the driver at the pedal 86. When the electronic control 48 detects that the throttle has become open to the extent being demanded by the driver the electronic control automatically returns to the operating mode in which further movement of the valve 84 is in response to movement of the pedal 86.Over the time period between times t7 and t8 the effect of increasing the percentage of throttle opposes the engine braking effect exerted by the clutch, and engine deceleration decreases (graph section 130) until the engine speed becomes substantially equal to the immediately hitherto substantially constant speed Sn of the input shaft 14 and clutch driven plate 32.

Thereafter the combined effect of the open throttle and the increasing torque transmitting capacity of the clutch 20 causes the synchronised speeds of the engine 8 and input shaft 14 to increase at the same rate to accelerate the vehicle 2 (graph section 132).

It will be seen in Fig. 3 that the throttle becomes open at the time t8 to substantially the amount being demanded by the driver, and time t8 is substantially the same time as when the speeds of the engine 8 and the input shaft 14 become equal.

Instead of using expiry of time period tx as a trigger to open to throttle and return it to driver control, the electronic control 48 may be programmed to calculate engine deceleration from engine speed observations and use that deceleration value in a calculation (taking account of the increasing braking effect of the re-engaging clutch and the opposing effect thereto of the opening throttle) to predict when the speeds of the engine 8 and input shaft 14 will become equal. Since the rate at which the electronic control 48 can open the throttle is known, the electronic control can calculate when to instruct the motor means 92 to start opening the throttle to ensure that the throttle becomes open to the amount Td (currently being demanded by the driver at the pedal 86) at the same time as the input shaft 14 and engine.speeds become equal.

The valve 84 may have restoring or spring means acting thereon to assist the motor means 92 in moving the valve 84 towards the zero throttle position.

In a modification the mechanical connection 94 can be extended by mechanical means 95 (Fig. 2) so that when the throttle is under driver control the mechanical connection 94, 95 transmits movement from the pedal 86 to the valve 84, the motor means 92 being used only to operate the throttle as illustrated by the curve in axes set III in Fig. 3 during the course of a gear change.

Such a modification using a Bowden cable and an electric motor is disclosed in our pending British Patent Application No. 8723546.

In Fig. 4 the petrol engine 8 has a fuel supply comprising a petrol injection system controlled by electronic control 48 (Fig. 2) and comprising the butterfly or flap valve 84 in an induction pipe 80A and a petrol injection arrangement 140 (known per se) operative in response to electrical signals on path 142 from the electronic control. In known manner the arrangement 140 supplies fuel in amounts automatically correlated to the extent to which the valve 84 is open. Thus when the engine 8 has the fuel injection system, the latter can be throttled substantially as illustrated in Fig. 3. In Fig. 4 references 92, 94, 96, 98 and 100 indicate the same or comparable parts as they do in Fig. 2.

In Fig. 5, diesel engine 8A has a fuel supply comprising a fuel metering valve system 150 known per se controlled in a known manner by a rack 152 moved, to vary the amount of fuel being supplied, by motion transmitted through the mechanical link 94 from the motor means 92 recieving control signals on the path 100. A rack or throttle position sensor 154 sends throttle position signals in the path 98 to the electronic control 48 (Fig. 2).

Claims

1) Apparatus for determining the speed of rotation of a clutch driven plate, the apparatus comprising a first sensor for sensing the speed of rotation of a gearbox output shaft, a second sensor for sensing which gear in a gearbox is engaged and control means for receiving signals from said sensors and calculating the clutch driven plate speed.

2) A power linc, to driver at least one ground running wheel of a motor vehicle, said powder line comprising an internal combustion engine giving a rotary motion output, fuel supply means to supply fuel to said engine, said fuel supply means comprising controllable throttle means openable and closable to vary the amount that the throttle means is open to increase and decrease supply of fuel to the engine, a change-speed gearbox having a rotary output shaft for supplying rotary motion to said ground running wheel and a rotary input shaft for receiving output torquf from the engine and a plurality of gear ratios between shafts, each gear ratio being engageable and disengageable in response to operation oE gear- ratio selector means in response to manual action oE a driver of the vehicle, a clutch interposed between said engine and said input shaft for transmitting engine output torque to the input shaft, clutch control. means operable to vary the torque transmitting capacity of said clutch over a range from a prc-dctermincn maximum capacity (clutch fully engaged) to substantially zero capacity (clutch fully disengaged), the clutch control means being responsive to occurence of a first signal indicative of a wish by the driver to disengage the currently engaged said gear ratio and being responsive to occurrence of a second signal indicative that another said gear ratio has been engaged, said clutch control means rcsponding to said first signal to cause the clutch automatically to disengage substantially fully and responding to said second signal to cause the clutch autonlatically to engage substantially fully, throttle control means to open and close said throttle means in response to driver initiated throttle demand signals, said control means being arranged to receive signals from a driven plate speed determining means which comprises a gearbox output shaft speed sensor and a gearbox condition sensor