Claims:We claim:

1. A method to control a vehicle speed of a vehicle, said method comprising:
increasing the vehicle speed to an upper threshold vehicle speed from a first vehicle speed;
coasting an engine of the vehicle by disengaging the engine from the transmission until the vehicle speed reduces to a lower threshold vehicle speed; and
engaging the engine with transmission to increase the vehicle speed to the upper threshold vehicle speed upon reaching the lower threshold vehicle speed.

2. The method as claimed in claim 1, wherein the lower threshold vehicle speed is lesser than the first vehicle speed.

3. The method as claimed in claim 1, wherein the upper threshold vehicle speed is greater than the first vehicle speed.

4. The method as claimed in claim 1, wherein receiving the first vehicle speed from a user of the vehicle.

5. The method as claimed in claim 1, wherein receiving the first vehicle speed based on an accelerator pedal position for a predefined time period.

6. The method as claimed in claim 1, wherein the first vehicle speed is an average of the upper threshold vehicle speed and the lower threshold vehicle speed.

7. The method as claimed in claim 1, wherein receiving the lower threshold vehicle speed and the upper threshold vehicle speed from the user of the vehicle.

8. A device (1000) for controlling a speed of a vehicle, said device (1000) comprising:
at least one vehicle speed sensors (102);
Characterized in that

a controller (101) to

- increase the vehicle speed to an upper threshold vehicle speed from a first vehicle speed;
- coast an engine of the vehicle by disengaging an engine from the transmission until the vehicle speed reduces to a lower threshold vehicle speed; and
- engage the engine with transmission to increase the vehicle speed to the upper threshold vehicle speed upon reaching the lower threshold vehicle speed.
9. The device (1000) as claimed in claim 8, wherein receiving the first vehicle speed from a user of the vehicle.

10. The device (1000) as claimed in claim 8, wherein the lower threshold vehicle speed is lesser than the first vehicle speed and the upper threshold vehicle speed is greater than the first vehicle speed. , Description:Field of the invention
[0001] The invention relates to a method and a device for controlling a speed of a vehicle.

Background of the invention
[0002] Cruise control is a known technology in road vehicles, wherein a desired cruise speed is set by a driver of the vehicle and then vehicle automatically maintains the set desired cruise speed continuously until the driver of the vehicle intervenes. The cruise control system comprises a set switch by which a specific speed can be selected by the driver as desired cruise speed. The cruise control system improves the driver comfort in steady traffic conditions. A button or a switch is usually provided, for example, on the steering wheel, to the driver to activate cruise control in the vehicle. The cruise control may also have separate "on” and “off” switches. There is a need to control the speed of the vehicle automatically such that the internal combustion engine in its best efficiency mode and thereby extract more fuel efficiency from the engine. This may be a difficult task while driving.

Short description of the drawing

[0003] An exemplifying embodiment of the invention is explained in principle below with reference to the drawing. The drawing is,

[0004] Figure 1 illustrates a schematic block diagram of a device for controlling a speed of a vehicle in accordance with this invention; and

[0005] Figure 2 illustrates a flowchart of the method to control the speed of the vehicle in accordance with this invention.

Description of the invention

[0006] Figure 1 illustrates a schematic block diagram of a device (1000) for controlling a speed of a vehicle. The device (1000) comprises at least one vehicle speed sensors (102); characterized in that a controller (101) to increase the vehicle speed to an upper threshold vehicle speed from a first vehicle speed; coast an engine of the vehicle by disengaging an engine from the transmission until the vehicle speed reduces to a lower threshold vehicle speed; and engage the engine with transmission to increase the vehicle speed to the upper threshold vehicle speed upon reaching the lower threshold vehicle speed.

[0007] An interface (103) of the device (1000) receives engine operating conditions from several sensors which are not shown in Figure 1. The engine operating conditions are, for example, an accelerator pedal position, a brake pedal position, a clutch pedal position, an engine speed, an engine temperature, an engine load, , etc. The accelerator pedal (200a), the brake pedal (200b) and the clutch pedal (200c) of the vehicle are as shown in Figure 1.

[0008] The at least one vehicle speed sensors (102) measure the vehicle speed and transmit the measured vehicle speed to the controller (101) of the device (1000). The controller (101) also receives the first vehicle speed. In an embodiment, the controller (101) receives the first vehicle speed from a user of the vehicle. For example, the user of the vehicle inputs a value of the first vehicle speed via an input button of the device (1000). In other words, the user inputs the first vehicle speed which is an average speed with which he desires to travel.

[0009] In another embodiment, the controller (101) automatically determines the first vehicle speed based on an accelerator pedal position for a predefined time period. The average vehicle speed maintained by the user of the vehicle is derived from the accelerator pedal position for the predefined time period. The average vehicle speed is considered as the first vehicle speed by the controller (101) of the device (1000).

[00010] The lower threshold vehicle speed is lesser than the first vehicle speed. The upper threshold vehicle speed is greater than the first vehicle speed. In an embodiment, the controller (101) receives the values of the upper threshold vehicle speed and the lower threshold vehicle speed from the user of the vehicle. The user provides the upper threshold vehicle speed and the lower threshold vehicle speed via the input button.

[00011] In another embodiment, the controller (101) calculates the upper threshold vehicle speed and the lower threshold vehicle speed based on the received first vehicle speed. The upper threshold vehicle speed is greater than the first vehicle speed by a first percentage. Similarly, the lower threshold vehicle speed is lesser than the first vehicle speed by a second percentage. In an instance, the first percentage is equal to the second percentage. In another instance, the first percentage is not equal to the second percentage. For example, the upper threshold vehicle speed is greater than the first vehicle speed by 5% and the lower threshold vehicle speed is lesser than the first vehicle speed by 5%. Here, the first percentage is equal to the second percentage which is 5%. The values of the first percentage and the second percentage are predefined by the user of the vehicle.

[00012] Once the controller (101) receives the first vehicle speed, the upper threshold vehicle speed and the lower threshold vehicle speed, the controller (101) increases the vehicle speed to the upper threshold vehicle speed from the first vehicle speed. Upon reaching the upper threshold vehicle speed, the controller (101) activates the coasting of the engine of the vehicle until the vehicle speed reduces to the lower threshold vehicle speed. This is done by disengaging the engine from the transmission until the vehicle speed reduces to the lower threshold vehicle speed. The clutch of the vehicle is in an open position. During coasting, the engine is disengaged from the transmission. Hence, due to reduced friction from the power train, the vehicle covers more distance during coasting. The engine will be automatically driven during coasting. In an embodiment, the engine is switched off during coasting. In another embodiment, the engine comes to an idle speed as the clutch is in an open position.

[00013] Once the lower threshold vehicle speed is achieved, controller (101) engages the engine to increase the vehicle speed to the upper threshold vehicle speed. The controller (101) demands the required torque to reach the upper threshold vehicle speed. The cycle of increasing the vehicle speed to the upper threshold vehicle speed and then coasting the engine unit the vehicle speed reaches the lower threshold vehicle speed repeats until the user intervenes by pressing either a brake pedal or an accelerator pedal. The user may also intervene by pressing an exit button provided by the device (1000).

[00014] Thus, the device (1000) help increase the fuel economy of the vehicle by using the coasting feature in the best possible manner. Also, the device (1000) aids the operation of the engine efficiently and thereby extract more fuel efficiency from the engine.

[00015] Figure 2 illustrates a flowchart of the method to control the speed of the vehicle in accordance with this invention. At step S1, the controller (101) increases the vehicle speed to the upper threshold vehicle speed from the first vehicle speed. The first vehicle speed, the upper threshold vehicle speed and the lower threshold vehicle speed are received by the controller (101). At step S2, coasting the engine of the vehicle by disengaging the engine from the transmission until the vehicle speed reduces to the lower threshold vehicle speed. At step S3, the controller (101) engages the engine to increase the vehicle speed to the upper threshold vehicle speed upon reaching the lower threshold vehicle speed. The method in accordance with this invention improves reduction in carbon dioxide. The method also provides improvement in fuel efficiency to the level of 10-40% depending on the gear and the engine zone where the user is driving the vehicle.

[00016] The method in accordance with this invention to control the vehicle speed can be used along with the concept of Internet of Things (IoT) and connected powertrains. In this case the decision to implement the steps involved in the method is taken based on the information over cloud, such as, information readily available on traffic conditions, speed limits, traffic signals, etc.

[00017] It must be understood that the embodiments explained in the above detailed description is only illustrative and does not limit the scope of this invention. The scope of this invention is limited only by the scope of the claims. Many modification and changes in the embodiments aforementioned are envisaged and are within the scope of this invention.