field of the invention

This invention relates to a device for controlling air-flow rate for internal combustion engine of motor vehicle. More specifically, it relates to a thermally-sensitive device for controlling air-flow rate to an internal combustion engine of motor vehicle.

State of the art:

In order to get smooth idling, either a bypass or a throttle in the inlet passage of the internal combustion engine has to be opened to a proper position, which allows sufficient amount of air to enter to the internal combustion engine. An idle adjustment screw mechanically coupled to the throttle, can be used to vary the position of the throttle for idling adjustment. However, during cold conditions, more amount of air is required to quickly start and stably run the internal combustion engine. Therefore, idle setting has to be modified accordingly.

Therefore, there is a need for an idle adjustment device which can automatically adjust the throttle position based on the temperature condition to ensure proper idling as well as provide instant starting to the internal combustion engine.

A Japanese patent publication JP9256910A - discloses a carburetor with a temperature sensing member to respond to the temperature conditions. However, the purpose of the carburetor is to merely adjust the air-fuel mixture.

There is a need for a thermally-sensitive arrangement for effectively varying the air-flow rate to the internal combustion engine, based on the temperature conditions. Further, there is a need for an air-flow rate control device that can be used in conjunction with an electronic fuel injection control unit which regulates the fuel injection based on the amount of air-flow rate.

Description of the invention
The invention discloses a thermally-sensitive device for controlling air-flow rate to an internal combustion engine of motor vehicle. The device comprises a housing with a front plate and a piston. The piston has a continuous bore extending from its head till an end of a piston rod. One or more springs are coupled between one side of the piston head and the front plate of the housing. One or more thermally-sensitive elements are coupled on the side of the piston head, which is not connected to the spring. The piston rod is mechanically connected to a throttle flap. The piston rod is adapted to vary the movement of the throttle flap based on the engine ambient temperature. The device further comprises a screw inserted into the continuous bore of through a hole in the front plate. The screw is selectively coupled to the throttle flap to vary the movement of the throttle flap.

The invention also discloses a device for controlling air-flow rate for internal combustion engine of motor vehicle. The device comprises a screw coupled to a thermally-sensitive mechanism. The position of the throttle flap is varied based on the position of the screw to control the idling of said internal combustion engine. The thermally-sensitive mechanism is adapted to control the movement of the throttle flap based on engine ambient temperature.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawings:

Figure 1 shows a partial side view of thermally-sensitive air-flow rate control device during cold condition, in accordance with an embodiment of the present invention; and

Figure 2 shows a partial side view of thermally-sensitive air-flow rate control device during warm condition, in accordance with an embodiment of the present invention;

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows partial side view of an air intake passage in a vehicle, showing a thermally-sensitive air-flow rate control device, in accordance with an embodiment of the present invention. The device (10) comprises a housing (12) with a front plate (13) and a piston (14). The device (10) is provided to an intake passage (15) of the internal combustion engine of the vehicle. The piston (14) has a continuous bore (16) at its centre. The continuous bore (16) extends from a head (18) of the piston (14) till an end (20) of a piston rod (21).

One or more springs (22) are coupled between one side of the head (18) of the piston (14) and the front plate (13) of the housing (12). One or more thermally-sensitive elements (26) are coupled to the other side of the head (18) of the piston (14), which is not coupled to the spring (22).

The piston rod (21) is mechanically coupled to a throttle flap (28) via a throttle cam provided on a throttle shaft in the throttle body assembly. The end (20) of the piston rod (21) is connected to the extension of the throttle cam.

With the help of an idle adjustment mechanism, the throttle flap (28) is made to open for a specific angle in order to receive minimum amount of air that is necessary to maintain the internal combustion engine in the idle condition. However, during cold conditions, this amount of air is not sufficient to start the internal combustion engine.

The position of the piston (14) is varied based on engine ambient temperature by the action of the thermally-sensitive element (26), which is explained below in detail.

The thermally sensitive element (26) is retracted when the engine ambient temperature is less than the normal temperature during cold seasons. Upon retracting, the thermally-sensitive element (26) varies the position of the throttle flap (28) further, to allow entry of more air to the internal combustion engine. Entry of more air to the internal combustion engine ensures quick starting of the internal combustion engine.

Figure 2 shows a partial side view of thermally-sensitive air-flow rate control device during warm condition, in accordance with an embodiment of the present invention. After the internal combustion engine runs for certain period, the temperature at the surrounding of the device (10) increases. The thermally-sensitive element (26) is expanded upon raise in the engine ambient temperature. As a result of this expansion, the throttle flap (28) is moved to a position to reduce the amount of air passage to the internal combustion engine.

In an embodiment of the invention, the thermally-sensitive element (26) is a flexible chamber filled with wax. Volume of the chamber or the space inside the chamber which accommodates the wax can be variable in order to accommodate the expansion/contraction of the wax.

In another embodiment of the invention, the thermally-sensitive element (26) is bimetallic element.
In yet another embodiment of the invention, the thermally-sensitive element (26) is a

shape—memory alloy element such as copper-aluminum-nickel alloy or nickel-titanium alloy.

In an embodiment of the invention, the idle adjustment mechanism can be used in conjunction with the thermally-sensitive device (10) of this invention. In this embodiment, the idle adjustment is implemented in the form of a screw (30). However, people skilled in the art know well that the idle adjustment mechanism can be implemented in various other forms such as rod, pin, lever, etc.

The screw (30) is inserted inside the continuous bore (16) of the piston (14) through a hole provided in the front plate (13) of the housing 12. The screw (30) is manually adjusted in order to contact to the throttle flap (28) for varying the movement of the throttle flap (28) independent of the piston rod (21).
The screw (30) can also be driven with the help of an actuator. The actuator can be a mechanical actuator, an electrical actuator, a pneumatic actuator, an electromagnetic actuator or a hydraulic actuator. With the help of the screw (30), the throttle flap (28) is moved to a position in order to receive minimum amount of air which is necessary to maintain the internal combustion engine in idle condition.

As an alternate embodiment, this invention is implemented as a device for controlling air flow rate for an internal combustion engine of a motor vehicle. The device comprises a thermally-sensitive mechanism which controls the movement of the throttle flap based on the engine ambient temperature. The device also comprises a screw, which is coupled to the thermally-sensitive mechanism. The screw is adjusted to vary the movement of the throttle flap for adjusting the idling of the internal combustion engine.
With the help of the screw, the position of the throttle flap can be varied easily in order to enable smooth idling. The present invention can be used in conjunction with electronic fuel injection control system to ensure efficient fuel supply and stable running of the internal combustion engine.

Air-flow rate to the internal combustion engine is varied automatically, based on the temperature conditions by using the thermally-sensitive element. For example, during cold condition, the throttle flap is moved such that more air is allowed to enter the internal combustion engine by the action of the thermally-sensitive element. Therefore, instant start of the internal combustion engine is possible.
When the engine ambient temperature becomes normal, the air flow rate can be reduced to sufficient level automatically.

The idle adjustment screw can be easily inserted through the continuous bore of the piston for adjusting the idling condition. Therefore it is simple to use the idle adjustment screw with the thermally-sensitive mechanism.

It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiment and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

VE CLAIM:

1. A thermally-sensitive device (10) for controlling air-flow rate to an internal combustion engine of motor vehicle, said device (10) comprising:

a housing (12) with a front plate (13) and a piston (14), said piston (14) having a head (18) and a piston rod (21) extending from said head;

at least one spring (22) coupled between one side of said head (18) and said front plate (13) of said housing (12);

at least one thermally-sensitive element (26) coupled to the side of the head (18) not connected to the said spring (22); and

said piston rod (21) mechanically connected to a throttle flap (28); said piston rod (21) adapted to vary the movement of the throttle flap (28) based on engine ambient temperature.

2. The device (10) of claim 1, wherein said thermally-sensitive element (26) is a chamber filled with wax.

3. The device (10) of claim 1, wherein said thermally-sensitive element (26) is a bimetallic element.

4. The device (10) of claim 1, wherein said thermally-sensitive element (26) is a shape-memory alloy element.

5. The device (10) of claim 1, wherein thermally-sensitive element (26) is adapted to vary the position of the piston (14) based on engine ambient temperature.

6. The device (10) of claim 1, wherein said piston (14) has a continuous bore (16), said continuous bore (16) extends from the head (18) of the piston (14) till an end of the piston rod (21).

7. The device (10) of claim 1 and claim 6 further comprising a screw (30) inserted inside the continuous bore (16) of said piston (14) through a hole provided in said front plate (13); said screw is connected to the throttle flap (28) to vary the movement of the throttle flap (28) independent of the thermally-sensitive element (26).

8. The device (10) of claim 7, wherein said screw (30) is driven by an actuator to vary the air-flow rate to said internal combustion engine.

The device (10) of claim 8, wherein said actuator is selected from a group comprising mechanical actuator, electrical actuator, an electromagnetic actuator, a pneumatic actuator, and hydraulic actuator.

10. A device for controlling air-flow rate for internal combustion engine of motor vehicle, said device comprising:

a thermally-sensitive mechanism, said thermally-sensitive mechanism is adapted to control the movement of a throttle flap based on engine ambient temperature; and

a screw coupled to said thermally-sensitive mechanism, wherein position of the throttle flap varies based on position of said screw.

11. The device of claim 10, wherein said thermally-sensitive mechanism comprises a housing having a front plate and a piston; said piston having a head and a piston rod; said piston having a continuous bore extending from said head till an end of said piston rod.

12. The device of claim 11, wherein at least one spring is positioned between said front plate of the housing and side of the head; a thermally-sensitive element attached the other side of the head not connected to said spring;

13. The device of claim 10 and 12, wherein said screw movably inserted inside said continuous bore through a hole provided in said front plate;

14. The device of claim 2, wherein said thermally-sensitive element is selected from a group comprising a chamber filled with wax, a bimetallic element, and a shape-memory alloy element.

15. The device of claim 1 and 2, wherein said thermally-sensitive element is adapted to vary the position of said piston based on engine ambient temperature.