CLIMB ASSISTING SYSTEM FOR MOTOR VEHICLES

Field of Invention:

The present invention relates to a Climb-assist system for a commercial vehicle for avoiding rollback at the instant of restarting the vehicle in an inclined road and enhancing drivability of the vehicle in the hilly terrain. This invention intends for holding the vehicle in hilly terrain by automatically actuating parking brakes at the instant of release of service brake.

Background of Invention:

In a commercial motor vehicle the driver needs to hold the vehicle with heavy payloads, and has to drive in the gradient which are the unavoidable hurdles come in path of every driver and in such un-prevalent conditions drivers need to hold and carefully move the vehicle in gradients. At the time of vehicle restart, controlling vehicle rollback with heavy payloads hugely depends on driver skills. In the running and vehicle stopping condition irrespective of the terrain driver needs to operate at most two pedals simultaneously. However at the time of gradient restart condition driver needs to operate all the three pedals in synchronization. Only skilled drivers will be able to smoothly operate the heavy loaded vehicle in hilly terrains without causing any accidents.

In order to accelerate the vehicle in an incline pathway or climbing in a hill condition, the driver has to shift his foot from the brake pedal to the accelerator pedal. However, during this transition period, the vehicle has a tendency to roll back, while try to move forward, as a result of the brakes being released since the driveline does not become engaged instantly upon a depression of the accelerator pedal.

The rollback of the vehicle is due to the combination of climbing in incline or graded road and the load or weight of the vehicle. Rollback also causes the clutch wear during the vehicle restart condition because of improper clutch - brake actuation. Minor accidents may occur in the hilly terrains at the time of vehicle restart condition. Vehicle operation in hilly terrain causes high driver fatigue and creates fear for travelling on hilly terrains. Hence, a need exists in commercial vehicles for a driver assist system to automatically control the clutch and brake sequence at the time of vehicle restart on the gradients.

Large extent of work has been carried over the years on development of Hill assist systems for automobiles. Hill assist system devices have been developed to overcome the above mentioned causes of rolling back of vehicles. In the related arts, hill holder device would comprise of multiple sensors such as clutch pedal, brake sensor, acceleration sensor, vehicle speed, gear sensor engine speed sensor and incline sensor, for arriving at logic to control the brake

U.S. 4,582,184 discloses a hill assist system which utilizes a linkage connection between clutch pedal and brake pedal to apply brakes when the clutch pedal is depressed on an incline. U.S. 2010/0168974 discloses a hill assist system which utilizes an anti-lock braking system electronic control unit (ABS ECU) for giving electronic control commands for controlling the brake application and release. The hill assists system proposed by US 2010/0168974 is applicable for vehicles with ABS and it is expensive. U.S 6315372 Bl discloses a hill assist system which has an automatic control system to hold the vehicle during hill stop condition by triggering a time delay to retain the brake pressure to apply brakes. In the meantime the driver can carry out restart operation. This system can be used for automatic/manual transmission with Automatic Clutch only. Also, there is a preset time delay which widely varies based on driver and road traffic condition.

U.S 6,679, 810 discloses a hill assist system which working based on the sensing of backward movement of vehicle. The brakes get actuated once the backward speed exceeds the pre determined set value. In this method, there is a requirement of additional vehicle backward motion sensor.
However, these conventional systems do not provide adequate protection against the rolling back of a truck. Moreover these conventional systems are complex in nature and incur high cost for adapting such systems.

Therefore, it is desired to provide a very simple and cost effective climb assisting system that provides adequate protection against the rolling back of the vehicle that is transitioning from a stationary position.

Object of the invention:
The main object of the present invention is to provide a hill climb assisting system for motor vehicles which uses manual transmission or automatic manual transmission.

Another objective of the present invention is to provide a climb assisting system that prevents the vehicle from being moved in an undesirable direction when the vehicle is on a sloped road.

Another objective of the present invention is to provide a climb assisting system that utilizes the available equipment in the vehicle with minimum add on devices, which makes the system inexpensive and easy to adopt.

Further objective of the present invention is to provide a climb assisting system that eliminates the necessity for continuously depressing a brake pedal at the instant of restarting a vehicle on a slope.

Summary of Invention:
The present invention relates to a climb assisting system for a commercial motor vehicle for aiding the driver to restart or move the vehicle on an incline without rollback. The climb assisting system is provided with a brake sensor for sensing the brake position of the vehicle, and to deliver signals with respect to the engagement of the service brake, a clutch sensor for sensing the clutch position of the vehicle, and to deliver signals with respect to the engagement of the clutch, and a vehicle speed sensor for sensing the speed of the vehicle, and to deliver signals with respect to the vehicle speed.

An actuator is connected with the parking brake of the vehicle, such that the actuator is arranged to actuate the parking brake of the vehicle and the parking brake is arranged to apply the parking brake with the vehicle when actuated by the actuator. The System utilizes a 3 port, 2 stage solenoid operated spring return pneumatic valve as the actuator to control the parking brake operation while vehicle restarting on the incline.

A control unit is provided to receive the inputs from the brake sensor, clutch sensor, and the vehicle sensor, and to provide output signals to the actuator for actuation of the parking brake. The control unit processes the inputs received from the clutch engagement sensor, service brake sensor and the vehicle speed sensor. The control unit delivers actuation signal to the actuator, whenever the clutch is disengaged, vehicle speed is relatively zero and the service brake is in a released position. An electric switch is provided at the driver compartment console to activate and deactivate the climb assisting system. The control unit and the actuator are integrated with the parking brake system of the vehicle, such that the system utilizes the parking brakes and brake circuit for preventing the vehicle from roll back.

The parking brakes are air type brakes and are operated by Pneumatic control units. Brakes are applied in default mode due to spring force, and whenever air supply is provided to the brake chambers, the brakes are released. The vehicle stop condition on a hill can be defined as, zero vehicle speed and the brake pedal operated. The vehicle restart condition on a hill can be defined as the clutch is depressed, vehicle speed is zero, brake is about to release and the throttle position is about to increase.

When the Control unit senses that the climb assisting switch is "on", brake is pressed, vehicle speed is zero and clutch is depressed, the control circuit actuates the parking brake as soon as the service brake is released. This allows the driver to restart the vehicle safely without any rollback. As the driver release the clutch, clutch sensor signal input is received by the hill assist device. This input signal from the clutch sensor or the input signal from the brake sensor enables the control unit to deliver a respective output signal to the actuator to release the parking brake thereby allowing smooth restart of the vehicle on the climb.

This improved climb assist system enables for preventing rollback of the vehicle when starting the vehicle in an inclined road surface. This minimizes the load on clutch at the time of overlap between brake release and clutch engagement, whereas when the service brakes are used to hold the vehicle, the overload on clutch is very high at the time of overlap.

The climb assisting according to the present invention can be achieved with minimal modification in the existing design of the vehicle, and can be constructed using simple components thus providing a cost effective system for the vehicle to aid the driver to climb in an incline or gradient pathway. Brief

Description of the Drawings:

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.

Fig. 1 shows a schematic diagram of a climb assisting system for motor vehicle, in accordance to the exemplary embodiment of the present invention.

Fig. 2 shows the control steps involved in the climb assisting system for various operating condition of the vehicle, in accordance to the exemplary embodiment of the present invention.

Fig. 3 shows an electro-pneumatic circuit diagram of the climb assisting system in accordance to the exemplary embodiment of the present invention.

Detailed Description of Drawings:

The present invention relates to a commercial vehicle hill restart assist system which utilizes the air brakes of the vehicle to prevent rollback of the vehicle even when the brakes are released using a control circuit. The climb assisting system placed with the motor vehicle prevents rollback at the time of restarting or moving the vehicle on an incline. The vehicle is provided with the parking brake facility at least on one of the axle. The parking brakes are engaged in order to prevent the rollback of the vehicle at the time of restart. The brakes are applied by spring tension in default mode and the brakes are released by supplying air to the parking brake chambers.

Fig. 1 shows a schematic diagram of a climb assisting system for motor vehicle, in accordance to the exemplary embodiment of the present invention. The climb assist system described in accordance with the present invention is an electro-pneumatic circuit which uses the existing data equipment in the vehicle for restart assistance on a climb. The system has a climb assist switch (1) provided to activate the climb assisting system and a control unit (2) providing control signals to operate an actuator (11), usually a solenoid valve, which actuate the parking brakes (12) provided with the vehicle. The climb assist switch (1) is placed near the driver console for ease of accessibility. Driver need to switch "ON" to enable the Climb assisting system to start functioning of the control system. Once the vehicle starts travelling in Ghat roads of any steep roads, driver can keep the vehicle ready for climb restart assistance.

The control unit (2) described in accordance with the present invention is a micro controller or microprocessor which takes digital input signals and processes the control logic and provides output signals with respect to the input received signals. The control unit (2) can also be a set of logic gates sequenced to process the input signal and provide the output signal. The control unit (2) is placed inside the vehicle cabin around the driver console. Brake sensor (3) or a brake switch mentioned in accordance to the present invention is an "on/off sensor, which is placed at the brake pedal inside the cabin. This sensor is used to sense the brake application in the vehicle. The brake pedal is equipped with the push button type sensor to sense the brake application, and the brake sensor changes its state when the brake application is initiated and at the instant of complete release of brakes.

The sensor output is generally supplied to Engine management system or it is available in the CAN controller. The sensor output can be obtained for climb assist device from any of the two controllers. In case, non ECU vehicles, the signal can be directly obtained from the sensor with necessary signal amplification. The output of the brake sensor is fed to the Climb assist system control unit. The brake sensor is a form of limit switch which is by default in off state "0" and at the initiation of brake engagement the state changes to "1".

Clutch sensor (4) or clutch switch mentioned in accordance to the present invention is an "on/off' sensor, which is placed at the clutch pedal inside the cabin. This sensor is used to sense the clutch engagement and disengagement. In case of manual transmission, the clutch pedal is equipped with a push button type sensor to sense the clutch pedal position and incase of automatic manual transmission the clutch position is sensed with an integrated sensor. The clutch sensor changes its state when the clutch is completely disengaged and at the instant of start of clutch engagement. The sensor output is generally supplied to Engine management system or it is available in the CAN controller. The sensor output can be obtained for climb assist device from any of the two controllers. In case, non ECU vehicles, the signal can be directly obtained from the sensor with necessary signal amplification. The output of the clutch sensor is fed to the Climb assist system control unit. The clutch sensor is a form of limit switch which is by default in off state "0" and when the clutch is completely disengaged the state changes to "1".

Transmission gearbox (5) mentioned in accordance with the present invention is a manual gearbox or automatic manual gearbox coupled with Engine through clutch assembly. The gearbox (5) has plurality gear speeds, and an inbuilt vehicle speed sensor (6). The vehicle speed sensor works on the principle of "Hall Effect".

The transmission gearbox of the vehicle is provided with a vehicle speed sensor works on the Hall Effect principle, to produce voltage pulse based on the vehicle speed. The voltage generated is zero when the vehicle speed is zero. The vehicle speed can also derived from the Antilock braking system (ABS) Electronic Control Unit (ECU) in case of ABS brakes installed in the vehicles. The vehicle speed input is provided to the climb assist system control unit (2) for processing the signal.

A 3 port, 2 stage solenoid operated spring return valve is provided as actuator for activating the parking brakes when signaled by the control unit. The signal to the solenoid valve is controlled by the control unit using a predefined logic. The solenoid valve (11) is placed in the parking brake circuit between GHCV (10) and parking brake chamber (12). In case of vehicles with single axle parking brakes, the solenoid valve (11) is mounted very close to parking brake chambers with a T joint for distributing air to LH & RH brake chambers. This arrangement reduces the air loss during the braking application. Whenever the climb assist system is enabled, electrical signal is passed to the Solenoid valve (11) which thereby actuates the parking brakes of the vehicle.

An air compressor (7), such as reciprocating type positive displacement pump which gets drive from Engine timing gears is provided with the climb assist system. Compressed air is stored in the air tanks for vehicle operations like braking, air suspension and auxiliary functions. Compressed air from compressor is directed to System protection valve (SPV) (8). At this valve the air is distributed to front brakes, rear brakes, parking brake and auxiliary functions. One of the lines from SPV (8) is directed to the parking brake tank (9). The compressed air in the parking brake tank (9) is used to control the actuation of parking brakes. Graduated hand control valve (GHCV) (10) is provided to control the brake operation.

The parking brakes are applied when air is not supplied or when the air is drained from the line.
In operation, the system operates for sensing the clutch disengagement using the clutch sensor on the vehicle, and Sensing the service brake application using the brake sensor with vehicle having air brake system, and Sensing vehicle speed from transmission box. The control unit delivers signal to the solenoid valve, whenever the clutch is disengaged, vehicle speed is zero and the service brakes are in released position. The solenoid valve is actuated as instructed by the control unit and operates the parking brake provided with the vehicle.

Fig. 2 shows the control steps involved in the climb assisting system for various operating condition of the vehicle, in accordance to the exemplary embodiment of the present invention. The control sequence carried out by climb assist system at different vehicle operation is described and the functioning is detailed. Whenever the climb assist switch (1) is placed on "ON" position, as per the step (13), the climb assist system is initiated and starts for functioning. The control unit checks for the state of the clutch sensor (4) as indicated in the step (14), and check for the state of the vehicle speed sensor (6) as indicated in the step (15) the position of the service brake as mentioned in the step (16). An AND logic is provided for the above steps, in which the control unit (2) process the inputs received from the clutch sensor (3), brake sensor (4) and the vehicle speed sensor (6) and based on the input signals, the control unit (2) outputs signal to the solenoid valve (11).

During vehicle stopping operation initiated by the driver, the clutch depressed condition (14) achieved, vehicle speed condition (15) is not achieved and the service brake condition (16) also not achieved. Since the conditions (14), (15) and (16) are in AND control logic, the hill assist device is in deactivated mode and solenoid valve will not energized (20) to actuate the parking brake.

During standing condition on a climb, brake is pressed and vehicle speed is zero, and the conditions (16) and step (14) are achieved and the vehicle speed condition (15) is not achieved, the hill assist device stay in the deactivated mode and the solenoid valve will not energized (20). During standing condition on a flat road, the parking brake is not applied and vehicle speed is zero, this achieves the condition (16) and (15) and clutch depress condition (14) will not be achieved, this keep the hill assist system in a deactivated mode and solenoid valve will not get energized. At the time of vehicle restart, clutch is depressed, brake is released and vehicle speed is zero, thus all the conditions (14), (15) and (16) are achieved, and the hill assist device is activated and the solenoid valve is energized (20). The energisation of the solenoid valve actuates to apply the parking brakes on to the vehicle. This function prevents rollback of the vehicle and allows the driver to comfortably raise the throttle and release the clutch smoothly.

At the instant, when the driver starts engaging the clutch to restart the vehicle, the condition (14) will not be achieved and immediately, control unit (2) de-energizes the solenoid valve (11) leading to step (20) followed by release of parking brakes. During normal braking operation to reduce the vehicle speed, only brakes are applied, thus all the three conditions will not be satisfied to actuate the solenoid valve. During intermediate gear changing operation, Clutch is disengaged, brake is not applied and vehicle speed is more than zero, and this keep the solenoid valve in inactivated condition and the parking brakes are not applied.

Fig. 3 is the electro pneumatic circuit diagram of the climb assist device in accordance with the present invention. Climb assist device circuit is integrated with the brake circuit as shown in the Fig. 3. Air is sucked from the air filter by the compressor (7), and the compressed air passes through DDU (8) which acts as a filter and the air is distributed to front brakes, rear brakes, parking brake (12) and for the auxiliary purpose, and from the auxiliary port of SPV (9), the compressed air is routed to GHCV (10). In normal condition, when GHCV (10) is actuated air is passed to the parking brake chambers and the parking brakes (12) are keep in released condition. When air supply is shut off at GHCV (10), the parking are brakes are made to applied condition.

The solenoid valve acting as an actuator (11) is introduced between the GHCV (10) and the parking brake chambers (12). In normal course of action, the air supply from GHCV (10) to parking brakes is not interrupted by solenoid valve. The compressed air from GHCV (10) comes to inlet port (11a) and passes through the outlet port (l1b) and the air is supplied to parking brake chambers (12). When the solenoid valve (11) is actuated, the valve shifts to second stage where, inlet port (11a) of the solenoid valve is plugged and outlet port (1 lb) is connected to the open atmosphere port (l1e). In this stage, the compressed air available at the parking brake chambers is released to atmosphere and the brakes (12) are applied. Thus, when the climb assist device is activated, a signal to Solenoid valve (11) is sent and the parking brakes (12) are applied to prevent roll back of the vehicle.

To restart the vehicle, the driver starts applying throttle and simultaneously engaging the clutch. At the instant when the clutch starts engaging the Clutch sensor (4) signal is off, thereby causing deactivation signal to the solenoid valve (11) through the control unit (2). This action connects the input port (11a) to the output port (11b) by supplying compressed air to the brake chambers (12) followed by release of parking brakes. The control unit (2) receives inputs from the clutch sensor (3), brake sensor (4) and the vehicle speed sensor (6) and based on the input signals, the control unit (2) outputs signal to the solenoid valve (11).

The parking brakes are released when anyone of the above mentioned condition is not met. This improved system aids the driver to hold the vehicle in hilly terrain by automatically actuating parking brakes at the instant of release of regular service brake.

This improved climb assist system enables for preventing rollback of the vehicle when starting the vehicle in an inclined road surface. This minimizes the load on clutch at the time of overlap between brake release and clutch engagement, whereas when the service brakes are used to hold the vehicle, the
overload on clutch is very high at the time of overlap.

The climb assisting according to the present invention can be achieved with minimal modification in the existing design of the vehicle, and can be constructed using simple components thus providing a cost effective system for the vehicle to aid the driver to climb in an incline or gradient pathway.

The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We claim:

1. A climb assisting system for motor vehicle, the system comprises,

a brake sensor (3) for sensing the brake position of the vehicle, and to deliver signals with respect to the engagement of service brake;

A clutch sensor (4) for sensing the clutch position of the vehicle, and to deliver signals with respect to the engagement of the clutch;

A vehicle speed sensor (6) for sensing the speed of the vehicle, and to deliver signals with respect to the vehicle speed;

an actuator (11) connected with a parking brake (12) of the vehicle, wherein said parking brake (12) is arranged to apply brake whenever said brake is actuated by the actuator (11);

a control unit (2) receiving inputs from said brake sensor (3), clutch sensor (4), and the vehicle sensor (5), and outputs signal to said actuator (11) for actuation of said parking brake (12), wherein the control unit (2) delivers actuation signal to said actuator (11), when the clutch is disengaged, vehicle speed is relatively zero and the service brake is in a released position.

2. The climb assisting system as claimed in claim 1, wherein a climb assist switch (1) is provided with said system to activate said control unit (2).

3. The climb assisting system as claimed in claim 1, wherein said control unit provides control signals to activate the actuator (11) to actuate the parking brake (12) of the vehicle.

4. The climb assisting system as claimed in claim 1, wherein control unit (2) is a microcontroller or a controller with a PLC (programmable logic circuits) program or a set of logic gates.

5. The climb assisting system as claimed in claim 1, wherein said actuator (11) is a solenoid operated spring return pneumatic valve.

6. The climb assisting system as claimed in claim 1, wherein said parking brake (12) is an air type brake or a pneumatic brake.

7. The climb assisting system as claimed in claim 1, wherein said brake sensor (3) is a push button type sensor.

8. The climb assisting system as claimed in claim 1, wherein said vehicle speed (6) sensor is a Hall Effect sensor which generates voltage pulse signals.

9. The climb assisting system as claimed in claim 1, wherein speed sensor (6) senses the vehicle speed from speed transmission box (5) of said vehicle.

10. The climb assisting system as claimed in claim 1, wherein said clutch sensor (4) is a push button type sensor sensing the position of the clutch.

11. The climb assisting system as claimed in claim 1, wherein said vehicle is operated with the parking brake (12) on at least one axle of the vehicle.

12. The climb assisting system as claimed in claim 1, wherein said vehicle uses manual transmission or automatic manual transmission.