CRUISE CONTROL SYSTEM AND METHOD FOR MAINTAINING AND REGULATING CONSTANT FUEL VOLUME

FIELD OF INVENTION

The present invention generally relates to a cruise control system and a method and more specifically to a cruise control system and method for maintaining constant fuel volume in a desired range of cruise speed.

BACKGROUND OF INVENTION

In the modern era of automobiles electronic systems have replaced most of the mechanical systems controlling the vehicle and engine. In a new generation engine an Electronic Control Unit (ECU) controls all performance parameters of a vehicle. It is possible to control the ECU according to the specific requirements of the end user based on the vehicle application.

Cruise control is a system which enables the driver to cruise the vehicle on highways with out pressing accelerator pedal. Cruise control was invented long before and now it exists in both mechanical and electronic form in vehicles. Main purpose of cruise control is to maintain the constant vehicle speed and avoid driver fatigue caused due to pressing accelerator pedal for a long period. The present invention focuses on improving the fuel efficiency of a Commercial vehicle using an advanced version of existing cruise control system.

Cruise control is a very common system spotted in almost all high end passenger cars and some of the commercial vehicles. When the vehicle is traveling in a highway where traffic conditions and environmental factors do not interrupt the vehicle speed, driver activates the Cruise control logic by pressing set speed switch in the cockpit. ECU takes the current vehicle speed as input and keeps the vehicle speed constant by governing the fuelling to the engine. For ensuring the fault free and safe operation of the system ECU uses a number of sensor inputs for shutting off the cruise control module. Some of such sensors are Accelerator pedal sensor, Brake pedal sensor, Clutch pedal sensor, Vehicle speed sensor, Engine speed sensor, any major sensor / switch which senses error or failure in the vehicle, sensor that senses the vehicle acceleration if it is too high (vehicle on down gradient while in cruise mode) and sensors that senses vehicle deceleration if it is too high (Vehicle on up gradient).

A conventional cruise control system performs cruise control which maintains a travel speed of a vehicle at a set vehicle speed of a vehicle at a set vehicle speed set by a vehicle driver as a target vehicle speed performs adaptive cruise for maintaining a distance to a preceding vehicle to be constant.

However, in the existing cruise control system and in the method of it, the ECU increases the fuel consumption rapidly when the vehicle is executing an up gradient to maintain the constant speed. The cruise control is shut off in an up gradient when deceleration of the vehicle is equal to the deceleration value set in the ECU. If the deceleration value is too low vehicle will come out of cruise mode frequently even in a comparatively plain road. If the vehicle deceleration value is set too high in the ECU vehicle will not come out of cruise mode even in high gradients and will try to climb the gradient in the set speed which results in higher fuel consumption. The vehicle comes out of cruise mode in a gradient only when the deceleration value exceeds the set value in ECU. Due to this the vehicle speed reduces rapidly on a gradient and makes it difficult for the driver to execute the gradient. Thus there arises a need for a cruise control system and a method to maintain a constant fuel volume for a desired range of speed for improved fuel efficiency and for a better feel for the vehicle driver in the vehicle behavior.

OBJECT OF INVENTION

An object of the present invention is to provide a cruise control system to maintain and to regulate a constant fuel volume in a vehicle for a desired range of cruise speed for improved fuel efficiency and for a better feel for the vehicle driver in the vehicle behavior.

Another object of the present invention is to provide a cruise control method to maintain and to regulate a constant fuel volume in a vehicle for a desired range of cruise speed for improved fuel efficiency and for a better feel for the driver in the vehicle behavior.

SUMMARY OF INVENTION

According to one aspect of the invention which achieves the objectives relates to a cruise control system for maintaining and regulating fuel volume in a vehicle, the cruise control system comprises an electronic control unit (ECU) capable of being activated by a cabin switch. A cruise activate switch which is activated upon activating the cabin switch to aid the ECU to determine the current speed of the vehicle as the vehicle speed. Sensors and modules to aid the ECU to continue and to quit cruise mode. A cruise controller capable of being activated and controlled by the electronic control unit. A fuel governor which regulates the volume of the fuel injected to the vehicle. A timer which decides the time required for the ECU to calculate the required fuel volume based on the previous states of the vehicle. A constant fuel cruise controller which activates a fuel throttle as desired by the cruise controller and the constant fuel cruise controller activates the fuel throttle in such a way that it can be maintained in a desired position to inject a desired volume of fuel to the vehicle determined by the cruise controller.

According to another aspect of the invention which achieves the objectives relates to a method of maintaining and regulating fuel volume in a cruise control of a vehicle, the method comprising the steps of activating the cruise mode by a cabin switch and a cruise activate switch. Controlling the fuel volume by the electronic control unit (ECU) such that the current speed of the vehicle is made as the vehicle speed for a set predetermined time period. Calculating the average fuel volume consumed by the vehicle for a set predetermined time period by the ECU and feeding it to cruise controller. Allowing the vehicle to enter the cruise mode by allowing the cruise controller to control the constant fuel cruise controller (CFCC) to position the fuel throttle in a desired position such that the fuel throttle injects the average fuel volume to the vehicle calculated by the ECU. Retaining the vehicle in cruise mode for a set predetermined cruise speed range. Monitoring the vehicle speed if the vehicle speed is within the set predetermined speed range. Exiting cruise mode when the vehicle speed is out of the set speed range;

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be discussed in greater detail with reference to the accompanying Figures.

Fig. 1 illustrates a block diagram of a cruise control system for maintaining and regulating fuel volume in a vehicle, in accordance with an exemplary embodiment of the present invention; and

Fig. 2 illustrates a flow chart depicting a method for maintaining and regulating fuel volume in a cruise control of a vehicle, in accordance with another exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to fig. 1, a block diagram of a cruise control system is illustrated in accordance with an exemplary embodiment of the present invention. The cruise control system (100) is implemented with an Electronic control unit (ECU) (103), a cruise controller (104), a fuel governor (105), a timer (106), a constant fuel cruise controller (CFCC) (107) and a fuel throttle (108).

The cruise mode is activated by switching ON the cabin switch (101) which is located in the driver's cabin of the vehicle. In association to turning ON the cabin switch and the cruise activate switch (102), the vehicle can be allowed to enter the cruise mode by the ECU and the cruise controller.

The ECU present in the cruise control system monitors various parameters from the modules and various parameters from the sensors namely Shut off conditions module (109), Engine ON/OFF module (110), Speed sensor (111), Accelerator pedal sensor (112), Clutch pedal sensor (113) and Brake pedal sensor (114).

Apart form the above parameters, the other parameters namely, Cruise control shutoff by driver (cruise switch), Engine doesn't run in normal mode (any other serious fault in engine), Control switch errors, Brake defective, Accelerator pedal defective, Clutch defective, Engine speed detection defective, Vehicle speed detection defective, Boost pressure sensor defective, Rail pressure sensor defective, Deceleration too high for an applicable time (redundant brake), Acceleration too high for an applicable time, Vehicle/engine speed ratio too high & suspend mode is not active, Vehicle/engine speed ratio too low, Clutch actuated without suspend mode or suspend mode unusually finished, Inadmissible gear (first, reverse or neutral).Vehicle speed is outside the admissible range, Engine speed too high or too low, or low idle requested by driver, Cruise control violated for an applicable time, Governor deviation (actual set point) too high for an applicable time, Gear shifting active, Shutoff request by max speed limitation, Shutoff request by the variable speed governor, Hand brake activated, Engine brake pre selection, "engine brake on" at released accelerator pedal are also monitored by the ECU.

Once any of these parameters necessitate the ECU to make the vehicle exit the cruise mode, the ECU will accordingly make the vehicle exit the cruise mode.

Upon turning ON the cabin switch followed by turning ON the cruise activate switch, the ECU will determine the current speed of the vehicle as the vehicle speed. The ECU controls the fuel governor such that the current speed of the vehicle at the time of activation of the cruise control switch is taken as the vehicle speed for a predetermined time period. The ECU then calculates the cruise speed based on the average fuel volume yielded by the fuel governor in the previous states of the vehicle. Subsequently, the ECU provides the average fuel volume calculated by it to the cruise controller and lets the cruise controller to let the vehicle enter into the cruise mode and thereupon the cruise controller triggers the constant fuel cruise controller thereby making the vehicle enter the cruise mode. The constant fuel cruise controller determines the position of the fuel throttle by activating it such that the fuel throttle is locked in a desired position to inject constant fuel volume to the vehicle calculated by the ECU.

The cruise controller allows the vehicle to be in the cruise mode within a set predetermined speed range. The cruise controller shuts the fuel throttle and stops the fuel injection when the vehicle is experiencing a negative gradient and restores the vehicle back to cruise mode when the vehicle looses the negative gradient. The cruise controller along with the ECU will make the vehicle exit from the cruise mode if the vehicle speed is out of the set predetermined speed range or if the ECU receives any signal from the sensors or modules.

Constant fuelling cruise controller (CFCC) will be highly beneficial in highway operations where vehicle can travel long distance with out braking. As described above, the ECU forms part of the vehicle which aids the vehicle driver to enter into cruise mode when desired and when appropriate. The vehicle is made to enter into the cruise mode by switching ON the cabin switch followed by activating the cruise activate switch. When the vehicle enters the cruise mode, ECU takes the vehicle speed as input for setting the cruise speed and allows the vehicle speed to vary between a pre set range of say between + 2 Kmph and - 4 Kmph which is set in the vehicle. This range can however be varied as desired by setting the desired speed range in the ECU. When the speed of the vehicle goes out of this set range, the cruise controller will make the vehicle exit the cruise mode.

Cruise controller dynamically receives inputs from all the sensors and shut off conditions through ECU. When the vehicle driver activates the cruise mode, at a required speed on highway, the ECU maintains a constant speed at that point of time by making the fuel governor pump appropriate volume of fuel for a specific time of say 20 seconds which is set in the throttle timer. This time can however be varied as desired. During this time period, the ECU calculates the average fuel consumption from the injected fuel quantity and the appropriate throttle position for the same. After the specific time period, the ECU automatically switches the vehicle over to CFCC by activating the fuel throttle such that the fuel throttle of the vehicle is in the desired position which was obtained from the ECU based on the previous vehicle states. From this point onwards, the vehicle starts cruising between the set speed ranges. The cruise speed range of the vehicle can be varied to the desired speed range.

Cruise control is normally activated when the vehicle is on a highway, in which various vehicle drive situations are to be considered for maintaining the vehicle fuel volume to be constant and to provide a better feel for the vehicle driver in the vehicle behavior When the vehicle is in plane surface drive, since the power demand for the vehicle remains almost constant, the present invention lets the vehicle speed to be retained when the cruise mode is active in this situation. This is achieved in the manner described above by letting the throttle positioner position the fuel throttle of the vehicle in an appropriate position calculated by the ECU. If the speed of the vehicle goes out of the set range, the ECU will make the vehicle exit the cruise mode and will make the vehicle enter the manual mode.

When the vehicle is in a slop surface to drive up, it creates a positive gradient on the vehicle. The present invention keeps the fuel injection volume constant and the speed of the vehicle will be reduced within a specified range say + 2 Kmph and - 4 Kmph if the cruise mode is activate in this situation. This is achieved in the manner described above by letting the throttle positioner to maintain the fuel throttle of the vehicle in an appropriate position calculated by the ECU. The said range can however be varied and set for different values. If the speed of the vehicle goes out of the set range, the ECU will make the vehicle exit the cruise mode and will make the vehicle enter the manual mode. Extra power required for keeping the speed constant on a gradient is avoided and improved fuel consumption could be achieved by maintaining the fuel volume constant.

When the vehicle is in a slop surface driving down, it creates a negative gradient on the vehicle. The present invention shuts off the fuel as the vehicle will be driving the engine (over run condition). So long as the vehicle speed is within the set range, the present invention will allow the vehicle to be in cruise mode. When the vehicle has a negative gradient, the ECU senses this and accordingly shuts the fuel throttle of the vehicle so long as the vehicle is experiencing a negative gradient. Once, the vehicle looses negative gradient, the cruise controller restores the fuel throttle to the appropriate position and allows the vehicle to run in the cruise mode.

When the vehicle is in a varying terrain driving, the power demand in actual conditions varies due to many factors such as terrain, aerodynamic resistance, road resistance, tire rolling resistance etc. In this situation, the present invention combines the two situations of up slop and down slop and accordingly the fuel volume is controlled. The fuel volume is kept constant when the vehicle is having positive gradient. The cruise controller shuts off the fuel throttle when the vehicle is having negative gradient and the throttle is resumed back to its appropriate position once the vehicle looses the negative gradient.

Thus the fuel volume for a desired range of speed is maintained and regulated thereby the fuel efficiency of the vehicle is achieved and the vehicle speed is allowed to vary within a set range and a better feel for the vehicle driver in the vehicle behavior is achieved in various vehicle driving situations.

Referring to fig. 2, a flow chart depicting a method for maintaining and regulating fuel volume in a cruise control of a vehicle in accordance with another exemplary embodiment of the present invention is illustrated. A method of maintaining a constant fuel volume for a desired range of speed for improved fuel efficiency and for a better feel for the driver in the vehicle may be achieved by the steps of activating the cruise mode by a cabin switch and a cruise activate switch. Controlling the fuel volume by the electronic control unit (ECU) such that the current speed of the vehicle is made as the vehicle speed for a set predetermined time period. Calculating the average fuel volume consumed by the vehicle for a set predetermined time period by the ECU and feeding it to cruise controller. Allowing the vehicle to enter the cruise mode by allowing the cruise controller to control the constant fuel cruise controller (CFCC) to position the fuel throttle in a desired position such that the fuel throttle injects the average fuel volume to the vehicle calculated by the ECU. Retaining the vehicle in cruise mode for a set predetermined cruise speed range. Monitoring the vehicle speed if the vehicle speed is within the set predetermined speed range and exiting cruise mode when the vehicle speed is out of the set speed range.

The fuel injected by the fuel throttle is constant when the vehicle is in cruise mode. The set predetermined cruise speed range can be varied to a desired cruise speed range. The fuel throttle is shut and the fuel injection is stopped when the vehicle is experiencing a negative gradient and is restored back to cruise mode when the vehicle looses the negative gradient The vehicle exits the cruise mode if the vehicle speed is out of the set predetermined speed range or if the ECU receives any signal from the sensors or modules.

Upon turning ON the cabin switch followed by turning ON the cruise activate switch, the ECU will determine the current speed of the vehicle as the vehicle speed. The ECU controls the fuel governor such that the current speed of the vehicle at the time of activation of the cruise control switch is taken as the vehicle speed for a predetermined time period. The ECU then calculates the cruise speed based on the average fuel volume yielded by the fuel governor in the previous states of the vehicle. Subsequently, the ECU provides the average fuel volume calculated by it to the cruise controller and lets the cruise controller to let the vehicle enter into the cruise mode and thereupon the cruise controller triggers the constant fuel cruise controller thereby making the vehicle enter the cruise mode. The constant fuel cruise controller determines the position of the fuel throttle by activating it such that the fuel throttle is locked in a desired position to inject constant fuel volume to the vehicle calculated by the ECU.

The cruise controller allows the vehicle to be in the cruise mode within a set predetermined speed range. The cruise controller shuts the fuel throttle and stops the fuel injection when the vehicle is experiencing a negative gradient and restores the vehicle back to cruise mode when the vehicle looses the negative gradient. The cruise controller along with the ECU will make the vehicle exit from the cruise mode if the vehicle speed is out of the set predetermined speed range or if the ECU receives any signal from the sensors or modules.

We Claim:

1. A cruise control system for regulating fuel volume in a vehicle, the cruise control system comprising:

an electronic control unit (ECU) (103) capable of being activated by a
cabin switch (101);

a cruise activate switch (102) which is activated upon activating said cabin switch to aid the ECU to determine the current speed of the vehicle as the vehicle speed;

sensors and modules to aid the ECU to continue and to quit cruise mode;

a cruise controller (104) capable of being activated and controlled by the electronic control unit;

a fuel governor (105) which regulates the volume of the fuel injected to the vehicle;

a timer (106) which decides the time required for the ECU to calculate the required fuel volume based on the previous states of the vehicle; and

a constant fuel cruise controller (107) which activates a fuel throttle (108) as desired by the cruise controller wherein the constant fuel cruise controller activates the fuel throttle in such a way that it can be maintained in a desired position to inject a desired volume of fuel to the vehicle determined by the cruise controller.

2. The cruise control system as claimed in claim 1, wherein upon activation of the cabin switch and the cruise activate switch, the ECU controls the fuel governor such that the current speed of the vehicle at the time of activation of the cruise control switch is taken as the vehicle speed for a predetermined time period.

3. The cruise control system as claimed in claim 2, wherein the ECU calculates the cruise speed based on the average fuel volume yielded by the fuel governor in the previous states of the vehicle.

4. The cruise control system as claimed in any one of the preceding claims, wherein the ECU provides the average fuel volume calculated by it to the cruise controller and lets the cruise controller to let the vehicle enter into the cruise mode and thereupon the cruise controller triggers the constant fuel cruise controller thereby making the vehicle enter the cruise mode.

5. The cruise control system as claimed in any one of the preceding claims, wherein the constant fuel cruise controller determines the position of the fuel throttle by activating it such that the fuel throttle is locked in a desired position to inject constant fuel volume to the vehicle.

6. The cruise control system as claimed in any one of the preceding claims, wherein the cruise controller allows the vehicle to be in the cruise mode within a set predetermined speed range.

7. The cruise control system as claimed in any one of the preceding claims, wherein the cruise controller shuts the fuel throttle and stops the fuel injection when the vehicle is experiencing a negative gradient and restores the vehicle back to cruise mode when the vehicle looses the negative gradient.

8. The cruise control system as claimed in any one of the preceding claims, wherein the cruise controller will make the vehicle exit from the cruise mode if the vehicle speed is out of the set predetermined speed range or if the ECU receives any signal from the sensors or modules.

9. A method for maintaining and regulating fuel volume in a cruise control of a vehicle, the method comprising the steps of:

activating the cruise mode by a cabin switch and a cruise activate switch;

controlling the fuel volume by the electronic control unit (ECU) such that the current speed of the vehicle is made as the vehicle speed for a set predetermined time period;

calculating the average fuel volume consumed by the vehicle for a set predetermined time period by the ECU and feeding it to cruise controller;

allowing the vehicle to enter the cruise mode by allowing the cruise controller to control the constant fuel cruise controller (CFCC) to position the fuel throttle in a desired position such that the fuel throttle injects the average fuel volume to the vehicle calculated by the ECU;

retaining the vehicle in cruise mode for a set predetermined cruise speed range;

monitoring the vehicle speed if the vehicle speed is within the set predetermined speed range; and

exiting cruise mode when the vehicle speed is out of the set speed range.

10. The method as claimed in claim 9, wherein the fuel injected by the fuel throttle is constant when the vehicle is in cruise mode.

11. The method as claimed in claim 9, wherein the set predetermined cruise speed range can be varied to a desired cruise speed range.

12. The method as claimed in claim 9, wherein the fuel throttle is shut and the fuel injection is stopped when the vehicle is experiencing a negative gradient and is restored back to cruise mode when the vehicle looses the negative gradient.

13.The method as claimed in claim 9, wherein the vehicle exits the cruise mode if the vehicle speed is out of the set predetermined speed nange or if the ECU receives any signal from the sensors or modules.