GB2279710A

GB2279710A - Vehicle with engine and transmission control system allows optional modification of signals to engine management

Info

Publication number: GB2279710A
Application number: GB9313253A
Authority: GB
Inventors: Roger Porter Jarvis; Ian Commander Maycock
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1993-06-26
Filing date: 1993-06-26
Publication date: 1995-01-11
Also published as: GB9313253D0

Abstract

A vehicle with an internal combustion engine having fuel injection under the control of an engine management system 77 responsive to signals 84, 86, 88 indicative of the current value of one or more vehicle/engine operating parameters. One or more sensors are provided for sensing operating parameters and a transmission controller 48 controls a clutch and optionally the selection of the operative ratio of a gearbox of the vehicle. Signals from at least one of the sensors pass e.g. airflow sensor 83 pass through signal modifying means preferably incorporated in the transmission controller 48 on their way to the engine management system 77 so that, when required, at least one sensor signal can be modified to change temporarily the operating settings of the engine to achieve temporarily desired vehicle performance conditions. In this manner engine torque can be temporarily reduced during changing the operative ratio of the gearbox or wasteful over supply of fuel to the engine can be reduced or avoided. <IMAGE>

Description

VEHICLE WITH ENGINE AND TRANSMISSION CONTROL SYSTEM This invention relates to a vehicle having an internal combustion engine with fuel injection controlled by an engine management system and a clutch and gearbox provided with a transmission controller which controls the engagement and disengagement of the clutch and may also control the selection of the operative ratio of the gearbox.

Such vehicles are well known and an example of such a vehicle is described and claimed in the Applicant's International Patent Application No.

W089/10282.

In such vehicles the selection of the operative gearbox ratio may be fully automated under the control of the transmission controller or may be manually instigated by the driver moving a selection lever.

It is already appreciated that in such vehicles it is desirable during ratio changes to reduce engine torque in order to improve ratio shifting quality.

For example, the previously referred to International Patent Application No. W089/10282 discloses a system in which an electric servo throttle control is provided in conjunction with a clutch control system so that the driver's throttle pedal demand can be overridden at the appropriate instances during a ratio change. It is also known to reduce engine torque during ratio changes by varying the timing of the spark in petrol engines.

It is a shortcoming of the above methods of reducing engine torque during gear changing that they either involve the addition of devices to override the driver's throttle demand or involve modification of the otherwise standard engine management system.

It is an object of the present invention to provide an improved and simplified arrangement which avoids both of the above difficulties.

Thus according to the present invention there is provided a vehicle with an internal combustion engine having fuel injection under the control of an engine management system responsive to signals indicative of the current value of one or more vehicle/engine operating parameters, one or more sensors for sensing said one or more operating parameters, a clutch, a gearbox, and a transmission controller controlling the clutch and optionally the selection of the operative ratio of the gearbox, the vehicle being characterised in that the signals from at least one of the sensors pass through signal modifying means on their way to the engine management system so that, when required, said at least one sensor signal can be modified to change temporarily the operating settings of the engine to achieve temporarily desired vehicle performance conditions.

One of the main uses for the present invention, as indicated above, is the reduction in engine torque during gearbox ratio changes. In such a use, when a gearbox ratio change is initiated, the sensor signal is modified to cause the engine management system to reduce engine torque.

Preferably, the signal modifying means forms part of the transmission controller.

It would be appreciated, that the main advantages of the present invention are that no modification of the existing throttle valve control arrangements are necessary nor is it necessary to modify the engine management system. Thus, an existing vehicle can easily and inexpensively be modified to include the torque reduction capability during ratio changes.

In many applications it is only necessary to modify the signals from one sensor in order to achieve torque reduction during gear ratio changes.

Conveniently, signals indicative of air flow rate to the engine may be passed through the signal modifying means for modification during gear ratio changes. Alternatively, signals indicative of throttle spindle rotational position or manifold vacuum pressure or throttle pedal position may be passed to the signal modifying means for modification during gear ratio changes.

In a further use of the present invention, when a sudden change in engine throttle setting is commanded (e.g. as part of a kickdown procedure for changing down in gearbox ratio) the sensor signal is modified to ensure that wasteful over supply of fuel to the engine is reduced or avoided.

The present invention also provides a method of temporarily modifying the engine settings in a vehicle equipped with an internal combustion engine under the control of an engine management system responsive to signals indicative of the current value of one or more vehicle/engine operating parameters, one or more sensors for sensing said one or more operating parameters, a clutch, a gearbox, and a transmission controller controlling the clutch and optionally the selection of the operative ratio of the gearbox, the method comprising passing the signals from at least one of the sensors through signal modifying means on their way to the engine management system and, when required, modifying said at least one sensor signal in said signal modifying means to change the operating settings of the engine to achieve temporarily desired vehicle performance conditions.

Several embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic representation of a vehicle embodying the invention; Figure 2 is a diagrammatic representation of the engine, clutch and transmission control arrangement of the vehicle of Figure 1, Figure 3 is a diagrammatic representation of a modified form of part of the control arrangement of Figure 2, and Figure 4 and 5 are diagramatic representations of alternative transmission controller arrangements.

Referring to Figure 1 this 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 10, which is of the lay shaft type, has a rotary input shaft 14, and, between the input and output shafts, a plurality of forward gear ratios and a reverse ratio are engagable in response to manual operation by the vehicle's driver of a gear ratio selector device 16. In this example, the selector device 16 is in the form of a gear lever from 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. It will be appreciated, however, that the selector device may comprise any form of manually actuable gear selector device from which gear ratio disengage and engage signals can be transmitted to gear ratio change means in the gearbox 10.

Driving torque is transmitted from the engine 8 to the gearbox 10 via a friction clutch 20 in a housing 22. In this example the clutch 20 is a push - type diaphragm spring clutch known per se having a cover 24 secured to a flywheel or other counter-pressure plate 26 rotated by the engine.

The clutch 20 includes a pressure plate 28 acted on by diaphragm spring 30 and a driven plate 32 with an internally splined central hub engaging splines on the gearbox 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 40 to a thrust rod 42 of a piston 43 of an 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 transmission controller 48 comprising computer means connected by signal path 50 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. The 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 occurrence 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 predetermined 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 predetermined maximum.

The electronic transmission controller 48 cansignal 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 controller 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 be used to observe the speed of the output shaft 12 and send signals to the electronic controller 48. Controller 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 the electronic control always knows which gear ratio is currently engaged and thus which ratio to use in the calculations.

Controller 48 is also connected by two signal paths 60 and 62 to the gearbox 10 and the gear lever 16 respectively. 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.

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 to such a signal controller 48 and hydraulic control 46 automatically function causing the clutch 20 automatically to disengage fully. Further manual movement of the knob 70 causes the shaft 64 to move, thus operating the gear ratio change means via the connection or linkage 18 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 the controller 48 and control 46 automatically to function so that the clutch 20 is re-engaged automatically.

Further details of the control of clutch 20 and gearbox 10 by controller 48 and gear lever 16 are given in the Applicants previously referred to International Patent Application No. WO89/10282.

In the example shown in Figure 2, engine 8 is a petrol engine having a fuel supply system comprising electromagnetically operated fuel injectors 76 under the control of an electronic engine management system 77 and an air-filter 78 through which air is fed to the engine via duct 80 which includes a throttle valve 79 controlled by a conventional driver operated accelerator pedal 81 via a linkage 82.

The engine management system 77 receives signals from a variety of vehicle/engine operating parameter sensors, depending on the particular fuel injection system installed on the engine, in order to determine the duration of the control pulses which open the injectors 76. For example, typically an airflow meter 83 provides signals Qa indicative of the volume flow rate of air into the engine and throttle valve position sensor 85 provides signals indicative of the rotational position of throttle valve 79 currently commanded by the accelerator pedal 8. Engine speed sensor 56 and one or more temperature sensors 88 are also connected to engine management system 77.

Throttle valve position sensor 85 is directly connected to engine management system 77 via line 86.

In accordance with the present invention line 84 from air flow meter 83 routes the airflow rate signals Qa to the engine management system 77 via the transmission controller 48. Thus the air flow signals Qa pass from meter 83 to transmission controller 48 via line 84 and are passed on to the engine management system 77 via line 87 (in unmodified Qa or modified Qam form, as will be described below).

As an alternative to providing a sensor 85 indicating the actual rotational position of throttle valve 79 one of more sensors or switches may be employed which indicate when the throttle valve is in one or more specific throttle valve positions (e.g. fully closed, fully open etc.). As a further alternative to sensor 85 a sensor may be provided to indicate the rotational position of accelerator pedal 81.

The air flow signals Qa are received by the transmission controller 48 via line 84 and are arranged to be modified at all times when a gear change command is signalled by gear lever transducer means 74 prior to routing onto engine management system 77. At all other times the airflow signals received by controller 48 are not modified prior to routing onto engine management system 77.

The above described arrangement operates as follows. When the vehicle operator initiates a gear change by movement of gear lever 16 this produces a signal from transducer means 74, which in addition to initiating disengagement and subsequent re-engagement of the clutch 20, as described above, also invokes modification of the air flow signal from meter 83 so that a modified flow signal Qam is supplied to engine management system 77 via line 87 until an ordered return to Qa is initiated some time after transducer 61 indicates that a new gear is engaged. This air flow signal Qam is modified (e.g.. reduced in size) to cause the engine management system to command a corresponding reduction in the amount of fuel supplied to the engine by injectors 76. This produces a consequent reduction in engine torque during the gear changes to improve ratio shifting quality as discussed above.

As will be appreciated, the main advantages of the arrangement in accordance with the present invention are that no modification of the existing throttle valve control is necessary nor is it necessary to modify the engine management system.

Thus an existing vehicle can be easily and inexpensively be modified to include this torque reduction capability during ratio changes.

Some forms of operating parameter sensor do not produce voltage outputs which are a direct measure of the relevant parameter. For example, hot wire anemometers (used to measure air flow rate) provide an indicate of flow rate by the variation in the supplied current to the wire element. Also some sensors provide a signal output imposed on a carrier frequency. If such a sensor is used it will be necessary for the sensor signals to pass through a signal conditioning means to provide a voltage based variable signal which the remainder of the circuitry can utilize.

The above signal conditioning means may form part of the outer peripheral circuitry of the transmission controller 48 or the engine management system 77. For example, Figure 3 shows sensor signals provided on lines 100 and 101 which are processed by signal conditioning blocks 102 and 103 which form part of the outer peripheral circuitry of the engine management system 77. The signal on line 100, which is an airflow signal from a hot wire anemometer, passes to the controller 48 via line 104 and is passed back to the heart 107 of the management system 77 via line 106. As described above, the controller 48 modifies the air flow signal during gear changes to cause a reduction in engine torque.

It will be appreciated that although the arrangement shown in Figure 3 does involve some invasion of the outer peripheral circuitry of the management system 77 it does not interfere in any way with the heart of the system (the CPU) in which the basic engine control logic is contained.

In a further alternative arrangement, illustrated diagrammatically in Figure 4, the transmission controller 48 used in Figure 2 or 3 may be constructed with peripheral circuitry 105 within which the modification of the signal in line 84 or 104 takes place. In the arrangement shown in Figure 4, the peripheral circuitry 105 receives a signal from the main CPU 110 of the transmission controller 48 via line 111 when a reduction in engine torque is necessary during a ratio change.

In a still further alternative arrangement, illustrated diagrammatically in Figure 5, the modification of the signal in line 84 of Figure 2 or line 104 of Figure 3 takes place in circuitry 120 which is disposed outside controller 48 and which receives a signal from the CPU 110 of comptroller 48 via line 111 when a reduction in engine torque is necessary during a ratio change.

It will be appreciated that by arranging for the signal modification to take place in peripheral circuitry 105 of Figure 4 there is no need for any in depth modification of controller 48. This advantage is further extended by arranging for the signal modification to take place in the external circuitry 120 of Figure 5.

Although the invention has been described above in relation to the modification, during gear changing, of an air flow rate signal in order to cause the engine management system to reduce the volume of fuel supplied to the injectors to reduce engine torque during gear changes, it will be appreciated that the invention could, alternatively, be set up to modify the signal from one or more other appropriate operating parameter sensors which are required to be fed to the management system 77.

For example, the throttle valve position signal (or accelerator pedal position signal if provided) and/ or the temperature sensor signal(s) could be modified during gear changing.

As a further alternative, in some engine management systems other parameters such as manifold vacuum pressure may be sensed and these signals modified during gear changing to reduce engine torque during gear changing.

Also, although in the example described above the invention is applied to a vehicle in which gear changes are initiated manually by movement of a gear selector lever 16, the invention is also applicable to a vehicle in which the selection of the operative gear ratio is fully automated under the control of the transmission controller 48.

Further, the invention is not only applicable to petrol engined vehicles but can also be used on vehicles powered by other forms of internal combustion engine such as a diesel engine when, for example, one or more of the parameter sensors signals fed to the engine management system would be modified during gear changing to cause a reduction in the fuel supplied to the diesel injectors.

Although the invention has been described above in relation to the temporary reduction of engine torque during gear changing to improve shift quality, the modification of the sensor signal can also be used to temporarily change the engine settings to achieve improvements in the economy and exhaust emissions levels of the engine.

For example, if the vehicle operator floors the throttle, either to initiate rapid vehicle acceleration or a so called "kickdown" procedure for changing down in gearbox ratio, this will be sensed, for example, by throttle valve sensor 85 or an accelerator pedal sensor (if provided).

In response to sensing such a condition one or more of the signals supplied to the engine management system may be modified (either inside or outside transmission controller 48 as described above) to prevent a sudden wasteful (and to a certain extent counter productive) step increase in the fuel supplied to the engine and to initiate a progressive increase in fuel supply which will ensure that the change in vehicle performance commanded by the operator is achieved without the supply of excessive fuel with its adverse effects on fuel economy and exhaust emissions.

In a still further alternative, when the input sensors to the transmission controller sense that the engine is in an overrun condition one or more of the signals supplied to the engine management system may be modified, either inside or outside controller 48, to cut-off or heavily reduce the supply of fuel to the engine thus again improving fuel economy and engine exhaust emissions. Such an arrangement would enable the feature of fuel cut-off or reduction on overrun to be easily and cheaply incorporated in a vehicle using an engine management system which does not include this feature.

Claims

1. A vehicle with an internal combustion engine having fuel injection under the control of an engine management system responsive to signals indicative of the current value of one or more vehicle/engine operating parameters, one or more sensors for sensing said one or more operating parameters, a clutch, a gearbox, and a transmission controller controlling the clutch and optionally the selection of the operative ratio of the gearbox, the vehicle being characterised in that the signals from at least one of the sensors pass through signal modifying means on their way to the engine management system so that, when required, said at least one sensor signal can be modified to change temporarily the operating settings of the engine to achieve temporarily desired vehicle performance conditions.

2. A vehicle according to Claim 1 characterised in that said at least one sensor signal is modified when a gearbox ratio change is initiated to cause the engine management system to reduce engine torque during the ratio change.

3. A vehicle according to Claim 1 characterised in that said at least one sensor signal is modified when a sudden change in engine throttle setting is commanded to ensure that wasteful over supply of fuel to the engine is reduced or avoided.

4. A vehicle according to any one of Claims 1 to 3 characterised in that signals indicative of air flow rate to the engine pass through the signal modifying means.

5. A vehicle according to any one of Claims 1 to 3 characterised in that signals indicative of throttle spindle rotational position pass through the signal modifying means.

6. A vehicle according to Claim 5 characterised in that the throttle spindle position signal is indicative of specific and discrete throttle positions only.

7. A vehicle according to any one of Claims 1 to 3 characterised in that signals indicative of manifold vacuum pressure pass through the signal modifying means.

8. A vehicle according to any one of Claims 1 to 3 characterised in that signals representative of a driver operated throttle pedal position pass through the signal modifying means.

9. A vehicle according to any one of Claims 1 to 8 characterised in that the modifying means forms part of the transmission controller.

10. A method of temporarily modifying engine settings in a vehicle equipped with an internal combustion engine under the control of an engine management system responsive to signals indicative of the current value of one or more vehicle /engine operating parameters, one or more sensors for sensing said one or more operating parameters, a clutch, a gearbox, and a transmission controller controlling the clutch and optionally the selection of the operative ratio of the gearbox, the method comprising passing the signals from at least one of the sensors through signal modifying means on their way to the engine management system and, when required, modifying said at least one sensor signal in said signal modifying means to change temporarily the operating settings of the engine to achieve temporarily desired vehicle performance conditions.

11. A method according to Claim 10 characterised in that said at least one sensor signal is modified when a gearbox ratio change is initiated to cause the engine management system to reduce engine torque during the ratio change.

12. A method according to Claim 10 characterised in that said at least one sensor signal is modified when a sudden change in engine throttle setting is commanded to ensure that wasteful over supply of fuel to the engine is reduced or avoided.

13. A vehicle constructed and arranged substantially as hereinbefore described with reference to and as shown in any one of Figure 2 to 5 of the accompanying drawings.