HILL-ASSIST DEVICE FOR A VEHICLE AND
METHOD OF ACTIVATING A HILL-ASSIST DEVICE

Field of invention;

The present invention relates to a hill-assist device for a vehicle for maintaining the braked condition of the vehicle stopped in an incline, even when the operator releases the foot brake keeping the clutch pedal pressed. The present invention also relates to a method of activating a hill-assist device

Background of invention;

Heavy vehicle such as trucks and buses often operate on roads in hilly terrains. Occasionally these heavy vehicles have to stop and restart on inclined paths. It might also be required to stop and restart a vehicle on the incline of flyovers and subways.

Stopping a vehicle on an inclined path is simple. The operator uses one foot to press the brake pedal to slow down the vehicle and when the vehicle has slowed sufficiently, he uses his second foot to press the clutch pedal to disconnect the drive from the engine to the wheels. This is done so that the engine does not stall at the time the vehicle is coming to a halt.

However, restarting a vehicle on an inclined path is not that much simple. The operator is already using both his feet, one for appl5dng the brake and the other for applying the clutch, and in order to restart the vehicle he needs to press the accelerator pedal also. The vehicle can be shifted to the

first gear, but the operator cannot release either the clutch or the brake. If the brake is released to press the accelerator pedal, the vehicle will roll back, inviting an accident. The clutch pedal should be released only after pressing the accelerator pedal and speeding up the engine.

Expert operators sometimes use parking brakes to hold the vehicle in place in a low incline. In this technique the operator releases the foot brakes after the parking brake has been applied. Then the accelerator is pressed. In this technique the operator has to judiciously release the clutch and the parking brake in order to restart the vehicle. Synchronizing the three activities is not that simple. The actuation becomes more difficult with the increase in the gradient of the path and with the increase in the load borne by the vehicle.

Restarting a vehicle using the aforementioned technique often leads to slippage of the clutch accompanied with clutch burning smell, and/or slippage of the wheels leading to lyre burning smell. Sometimes such technique leads to violent jerk as the vehicle moves, which could damage the propeller shaft. The vehicle may also roll back inviting an accident.

Hill assist devices have been developed in order to overcome the above mentioned problem of rolling back of vehicles. Hill holder device was invented by Studebaker way back in 1936. Such hill holder device would comprise of an incline sensor for measuring the forward incline of the vehicle and a disengaging mechanism. The Studebaker hill holder device was specifically designed for small vehicles such as cars and small trucks having hydraulic brakes.

It is also known in the art to devise hill assist systems using multiple sensors, such as sensors for slopes, clutch pedal, brake pedal, gear position and engine speed. These sensors are coupled with electronic control unit for actuating and controlling the hill assist systems. However, such sensor based hill assist devices are very complicated.

US patent application US 2010/0168974 discloses a hill assist system which utilizes an anti lock braking system and electronic control unit (ABS 86 ECU) for giving electronic control commands for controlling the brake application and release. The hill assists system proposed by US 2010/0168974 is complicated and expensive.

Accordingly, the inventors felt the need to a very simple and cost effective hill assist system, for heavy vehicles such as busses and trucks.

Summary of the invention;

Accordingly, the present invention provides a hill-assist device for a heavy vehicle comprising:

- a clutch booster operatively connected to a clutch pedal and a clutch actuating linkage for aiding in clutch disengagement, said clutch booster being equipped with a hydraulic cylinder and an air cylinder coupled together, said clutch booster being provided with an adapter for tapping out air from said air cylinder,

- a solenoid valve having pneumatic connection with the adapter of said clutch booster, said solenoid valve is fed with the air tapped out through said adapter upon activation of said clutch booster,

- a double check valve for selectively receiving air either upon activation of foot brake of the vehicle or upon activation of said solenoid valve.

- a quick release valve for receiving air delivered through said double check valve and being configured to aid in activating the braking device of the vehicle.

According to a preferred embodiment of the invention said solenoid valve is an electrically operated two port valve comprising:

- a supply port through which air is fed into the solenoid valve from said clutch booster, and

- a delivery port through which air is delivered to one of the inlet ports of said double check valve.

The solenoid valve may be electrically activated by a switch in the vehicle centre console.

Preferably, said double check valve is pneumatically connected to said foot brake of the vehicle through a load sensing valve.

According to a preferred embodiment of the invented hill-assist device, said double check valve comprises:

- two inlet ports, a first inlet port and a second inlet port, said first inlet port is pneumatically connected with said solenoid valve for receiving the air delivered through the delivery port of said solenoid valve, while said second inlet port is pneumatically connected with said load sensing valve for receiving air delivered from the foot brake,

- an outlet port through which air is delivered to said quick release valve, and

- a shuttle valve disposed between said first inlet port and said second inlet port for selectively connecting one of the inlet ports with the outlet port of said double check valve.

Preferably, functioning of said shuttle valve in opening and closing the inlet ports of said double check valve is achieved by developing pneumatic pressure difference between the inlet ports.

Preferably said quick release valve comprises:

- an input port in connection with the outlet port of said double check valve for receiving the air delivered through said double check valve,

- two output ports, each connected with a brake chamber of the vehicle, through which air is delivered to the respective braking chamber when the vehicle braking device is activated,

- an exhaust port through which air from the brake chambers of the vehicle are released when the vehicle braking device is deactivated.

The double check valve may be integrated with said quick release valve and said quick release valve may be mounted on the vehicle axle.

Preferably, said clutch booster is mounted on the gear box of the vehicle by means of a bracket.

The present invention also provides a method of activating a hill-assist device comprising the steps of:

- activating a solenoid valve having pneumatic connection with the air cylinder of a clutch booster; said clutch booster being linked with clutch pedal of the vehicle,

- tapping out air from the air cylinder of said clutch booster through an adapter provided with the air cylinder of said clutch booster and delivering the tapped out air to supply port of said solenoid valve,

- delivering air through delivery port of said solenoid valve to one of the inlet ports of a double check valve upon activation of the solenoid valve, wherein the other inlet port of said double check valve is in pneumatic connection with the foot brake of the vehicle,

- selectively connecting one of the inlet ports of said double check valve with the outlet port of said double check valve,

- delivering air from outlet port of said double check valve to inlet port of a quick release valve,

- providing air from output ports of said quick release valve onto the brake chambers of a braking device, thereby maintaining the vehicle under braked condition even when the pedal from the foot brake is released.

Preferably in the invented method of activating a hill-assist device said solenoid valve is electrically activated by a switch provided in the vehicle centre console.

According to a preferred embodiment of the invented method said double check valve has two inlet ports and an outlet port and is provided with a shuttle valve, said shuttle valve selectively closes one of the inlet ports of said double check valve and simultaneously connects the other inlet port with the outlet port of said double check. The functioning of said shuttle valve in opening and closing the inlet ports of said double check valve is achieved by developing pneumatic pressure difference between the inlet ports.

Brief Description of the Drawings;

For better understanding, an illustrative embodiment of the invention will be described with reference to the accompanying drawings. It will however be appreciated that the embodiments exemplified in the drawings is merely illustrative and not limitative to the scope of the invention, because it is quite possible, indeed often desirable, to introduce a number of variations in the particular embodiment that has been shown in the drawings.
Figure 1 shows a schematic representation of a hill assist device, according to a particular embodiment of the invention.

Figure 2 isometrically illustrates a hill assist device attached to a vehicle axle according to a preferred embodiment of the invention.

Figure 3 shows an isometric view of a clutch booster provided with an adapter, according to a particular embodiment of the invention.

Figure 4 shows an isometric view of a solenoid valve.

Figure 5 shows an isometric view of a double check valve.

Figure 6 shows an isometric view of a quick release valve.

Figure 7 shows an isometric view of a double check valve integrated with a quick release valve.

Figure 8 shows an isometric view of a clutch booster mounted on the gear box of the vehicle with a bracket.

Detailed description of the drawings;

Referring to figure 1 of the accompan3dng drawings, the invented hill assist device (1) comprises of a clutch booster (2) being provided with an adapter (3) a solenoid valve (4) having pneumatic connection with said clutch booster (2) through said adapter (3) (not shown in figure 2), a double check valve (5) for selectively receiving air either upon activation of the foot brake (6) of the vehicle or upon activation of said solenoid valve (4), and a quick release valve (7) for receiving air from said double check valve (5) and delivering the same to the brake chambers (8) of the braking device of the vehicle. The foot brake (6) of the vehicle comprises a foot brake valve (9), a brake pedal (not shown) and a load sensing valve (10) as seen in figure 1.

The clutch booster (2) is equipped with a hydraulic cylinder (not shown), an air cylinder (11) and a push rod (12) as seen in figures 1 and 3. The hydraulic cylinder is housed with the air cylinder (11). The adopter (3) is attached with the air cylinder (11). The clutch booster (2) is mounted on the gear box (13) of the vehicle by means of a bracket (14) as seen in figure 8 of the accompanying drawings.

The solenoid valve (4) controls the flow of air from the air cylinder (11) of said clutch booster (2) to said double check valve (5). The solenoid valve (4) is an electrically operated valve, having a supply port (15) and a delivery port (16) as shown in figure 4. The supply port (15) of the solenoid is pneumatically connected with the adapter (3) of the clutch booster (2), while the delivery port (16) of the solenoid is pneumatically connected with the double check valve (5) the as shown in figure 1.

The double check valve (5) has two inlet ports, a first inlet port (17) and a second inlet port (18), and an outlet port (19) as shown in figures 1 and 5. The first inlet port (17) is connected with the delivery port (16) of the solenoid valve (4), while the second inlet port (18) is pneumatically connected to the release port (20) of the foot brake valve (9), through the load sensing valve (10) as shown in figure 1. A shuttle valve (not shown) is disposed between the first inlet port (17) and the second inlet port (18) of the double check valve (5). When the double check valve (5) is in operating mode, the shuttle valve connects the outlet port (19) with that inlet port (17 or 18) which ever has higher pneumatic pressure, and simultaneously closes the other inlet port with the lower pressure.

Referring to figure 6 of the accompanying drawings, the quick release valve (7) has an input port (21) connected to outlet port (19) of the double check valve (5), and two output ports (22) connected with the brake chambers (8) of the vehicle, and an exhaust port (23). When the vehicle braking device is activated, air flows through the input port (21) of the quick release valve (7) into the brake chambers (8). When vehicle braking device is de-activated, air from the brake chambers (8) is released into the atmosphere through the exhaust port (23) of the quick release valve (7).

Preferably, the quick release valve (7) is mounted on the vehicle axle (24) as shown in figure 2. The double check valve (5) may be integrated with the quick release valve (7) as shown in figure 7.

When a vehicle is to be stopped in an incline, the operator applies the foot brake (6) by depressing the brake pedal (nor shown) and simultaneously applies the clutch pedal (not shown). The invented hill assist device (1) is then activated to maintain the braked condition of the vehicle so that operator is able to lift his foot from the brake pedal (not shown) and press the accelerator pedal (not shown) for restarting the vehicle.

When the foot brake (6) is applied, by depressing the brake pedal (not shown), air from the vehicle reservoir (not shown) flows out through the release port (20) of the load sensing valve (10) into the second inlet port (18) of the double check valve (5). The first inlet port (17) of the double check valve is closed by the shuttle valve and the second inlet port (18) is connected with the outlet port (19) of the double check valve so that air is delivered to the brake chambers (8) via the quick release valve (7).

When the clutch is now applied, air from the vehicle reservoir flows into the air cylinder (11) of the clutch booster (2). Air available in the air cylinder (11) is tapped out through the adopter (3) and is fed into the supply port (15) of the solenoid valve (4). The operator now switches on the solenoid valve (4) and releases the foot brake (6). Upon activation of the solenoid valve (4), air available at the supply port (15) of the solenoid valve (4) flows out through its delivery port (16) into the inlet port (17) of the double check valve (5). The inlet port (17) of the double check valve (5) is now connected with the outlet port (19) and the shuttle valve closes the inlet port (18) so that air is delivered to the brake chambers (8) via the quick release valve (7) and the vehicle is maintained under braked condition.

When the vehicle is to be restarted, the vehicle is shifted into first gear. The operator then presses the accelerator pedal (not shown) using the foot that he has lifted from the brake pedal, and the operator releases the clutch. When the clutch is released, air is released from the clutch booster (2) engaging the clutch and simultaneously air is released from the brake chambers (8) through the exhaust port (23) of the quick release valve (7). The vehicle accelerates and then the solenoid valve (4) is switched off.

Owing to its simplicity in construction and cost-effectiveness the invented hill-assist device (1) provides advantage over existing hill-assist devices. The inventors have successfully developed a hill-assist device utilizing standard air brake components without using costly electronic components like ABS and ECU, which no one ever endeavoured.

As already mentioned, the foregoing description is illustrative of the invention and not limitative to its scope, because it will be apparent to persons skilled in the art to devise other alternative embodiments without departing from the broad ambit of the disclosures made herein.

We claim:

1. A hill-assist device for a vehicle comprising:

- a clutch booster operatively connected to a clutch pedal and a clutch actuating linkage for aiding in clutch disengagement, said clutch booster being equipped with a hydraulic cylinder and an air cylinder coupled together, said clutch booster being provided with an adapter for tapping out air from said air cylinder,

- a solenoid valve having pneumatic connection with the adapter of said clutch booster, said solenoid valve is fed with the air tapped out through said adapter upon activation of said clutch booster,

- a double check valve for selectively receiving air either upon activation of foot brake of the vehicle or upon activation of said solenoid valve,

- a quick release valve for receiving air delivered through said double check valve and being configured to aid in activating and deactivating the braking device of the vehicle.

2. The hill-assist device as claimed in claim 1, wherein said solenoid valve is an electrically operated two port valve comprising:

- a supply port through which air is fed into the solenoid valve from said clutch booster, and

- a delivery port through which air is delivered to said double check valve.

3. The hill-assist device as claimed in claim 1, wherein said solenoid valve is activated by a switch in vehicle centre console.

4. The hill-assist device as claimed in any of claims 1 to 3, wherein said double check valve is pneumatically connected to said foot brake of the vehicle through a load sensing valve.

5. The hill-assist device as claimed in any of claims 1 to 4, wherein said double check valve comprises:

- two inlet ports, a first inlet port and a second inlet port, said first inlet port is pneumatically connected with said solenoid valve for receiving the air delivered through the delivery port of said solenoid valve, while said second inlet port is pneumatically connected with said load sensing valve for receiving air delivered from the foot brake,

- an outlet port through which air is delivered to said quick release valve, and

- a shuttle valve disposed between said first inlet port and said second inlet port for selectively connecting one of the inlet ports with the outlet port of said double check valve.

6. The hill-assist device as claimed in any of claims 1 to 5, wherein said quick release valve comprises:

- an input port in connection with the outlet port of said double check valve for receiving the air delivered through said double check valve,

- two output ports, each connected with a brake chamber of the vehicle, through which air is delivered to the respective braking chamber when the vehicle braking device is activated,

- an exhaust port through which air from the brake chambers of the vehicle are released when the vehicle braking device is deactivated.

7. The hill-assist device as claimed in any of claims 1 to 6, wherein said double check valve is integrated with said quick release valve.

8. The hill-assist device as claimed in any of claims 1 to 7, wherein said quick release valve is mounted on the vehicle axle.

9. The hill-assist device as claimed in any of claims 1 to 8, wherein said clutch booster is mounted on the gear box of the vehicle by means of a bracket.

10. A method of activating a hill-assist device comprising the steps of:
- activating a solenoid valve having pneumatic connection with the air cylinder of a clutch booster; said clutch booster being linked with clutch pedal of the vehicle,
- tapping out air from the air cylinder of said clutch booster through an adapter provided with the air cylinder of said clutch booster and delivering the tapped out air to supply port of said solenoid valve,

- delivering air through delivery port of said solenoid valve to one of the inlet ports of a double check valve upon activation of the solenoid valve, wherein the other inlet port of said double check valve is in pneumatic connection with the foot brake of the vehicle,

- selectively connecting one of the inlet ports of said double check valve with the outlet port of said double check valve,

- delivering air from outlet port of said double check valve to inlet port of a quick release valve,

- providing air from output ports of said quick release valve onto the brake chambers of a braking device, thereby maintaining the vehicle under braked condition even when the pedal from the foot brake is released.

11. The method of activating a hill-assist device as claimed in claim 10, wherein said solenoid valve is electrically activated by a switch provided in the vehicle centre console.

12. The method of activating a hill-assist device as claimed in any of claims 10 and 11, wherein said double check valve has two inlet ports and an outlet port and is provided with a shuttle valve, said shuttle valve selectively closes one of the inlet ports of said double check valve and simultaneously connects the other inlet port with the outlet port of said double check.

13. The method of activating a hill-assist device as claimed in claim 12, wherein functioning of said shuttle valve in opening and closing the inlet ports of said double check valve is achieved by developing pneumatic pressure difference between the inlet ports.